Mary Gerritsen - Academia.edu (original) (raw)
Papers by Mary Gerritsen
Microcirculation, Feb 1, 2010
Objective-To test the hypothesis that rapamycin inhibits induced microvascular hyperpermeability ... more Objective-To test the hypothesis that rapamycin inhibits induced microvascular hyperpermeability directly in vivo. Methods-Male golden Syrian hamsters (80-120g) were treated with either rapamycin (at 0.1, 0.5, 2, and 10 mg/kg i.p.) or vehicle at 24 hours and at one hour prior to preparation of the cheek pouch. Caveolin-1 scaffolding (1 mg/kg; positive inhibitory control) was injected i.p. 24 hours prior to the experiment. 10 −8 M vascular endothelial growth factor (VEGF) or 10 −7 M plateletactivating factor (PAF) were topically applied to the cheek pouch. Microvascular permeability and arteriolar diameter were assessed using integrated optical intensity (IOI) and vascular wall imaging, respectively. Results-Rapamycin at 0.1 mg/kg and 0.5 mg/kg significantly reduced VEGF-stimulated mean IOI from 63.0±4.2 to 9.7±5.0 (85% reduction, P<0.001) and 3.6±2.7 (95% reduction, P<0.001), respectively. Rapamycin at 2 mg/kg also lowered VEGF-stimulated hyperpermeability (40% reduction, P<0.05). However, 10 mg/kg rapamycin increased VEGF-induced microvascular hyperpermeability. Rapamycin at 0.5 mg/kg attenuated VEGF-induced vasodilation and PAFinduced hyperpermeability, but did not inhibit PAF-induced vasoconstriction. Conclusions-At therapeutically relevant concentrations, rapamycin inhibits VEGF-and PAFinduced microvascular permeability. This inhibition is 1) a direct effect on the endothelial barrier, and 2) independent of arteriolar vasodilation. Rapamycin at 10 mg/kg stimulates effectors that increase microvascular permeability.
PubMed, Feb 1, 1998
The activation of sphingomyelinase and the generation of ceramide has been proposed to mediate tu... more The activation of sphingomyelinase and the generation of ceramide has been proposed to mediate tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor (NF)-kappaB activation through its second messenger ceramide. Ceramide may also be an important regulator of cell growth, senescence, and apoptosis. Aberrant cell proliferation and apoptosis have been implicated in the rampant fibroblast proliferation and pannus formation characteristic of rheumatoid arthritis. However, the role of TNF-alpha and the sphingomyelinase pathway in the process have not been determined. The objective of this study was to determine whether TNF-alpha activates the sphingomyelin pathway in human synovial fibroblasts (HSF) and the potential role of ceramide in HSF proliferation and apoptosis. Cultured human synovial fibroblasts were stimulated with exogenous TNF-alpha, sphingomyelinase, and ceramide. Apoptosis was assessed by cell morphology and annexin V labeling. NF-kappaB and stress kinase pathway activation were determined by immunoblotting techniques. Sphingomyelinase activation was determined by quantitation of sphingomyelin and ceramide radioactivity in [14C]serine-prelabeled HSF cells. The addition of TNF-alpha (50 ng/ml) to HSF did not elicit detectable sphingomyelinase activation. TNF-alpha was shown to activate NF-kappaB (p65 translocation and degradation of IkappaBalpha) and the stress kinase pathway (phosphorylation of ATF-2, p38, and c-jun). In contrast, exogenous ceramide had no effect on these signaling pathways nor did ceramide stimulate the generation of interleukin-6 or interleukin-8. High concentrations of ceramide (> or =25 micromol/L) were cytotoxic, whereas lower concentrations of ceramide inhibited cell cycle progression. Thus, although TNF-alpha stimulates the NF-kappaB and stress kinase pathways in HSF, these effects of TNF-alpha are not associated with sphingomyelinase turnover or induction of apoptosis.
American Journal of Physiology-cell Physiology, Jun 1, 1986
The effects of dexamethasone on prostaglandin secretion by cultivated rabbit coronary microvascul... more The effects of dexamethasone on prostaglandin secretion by cultivated rabbit coronary microvascular endothelial (RCME) cells were investigated. Incubation of RCME cells with dexamethasone resulted in a time- and concentration-dependent decrease in prostaglandin accumulation in the culture media and reduced basal and A23187-stimulated prostaglandin (PG) E2 and 6-keto-PGF1 alpha release. The maximal effects of dexamethasone (50-80% inhibition) were achieved after 16-18 h of incubation with the steroid at a final concentration of 10(-7) M. The effects of dexamethasone treatment were partially reversed 24 h after removal of the steroid from the culture media. Dexamethasone treatment did not reduce arachidonic acid-stimulated prostaglandin synthesis, indicating that the level of inhibition was proximal to that of cyclooxygenase. The inhibitory effects of dexamethasone could be prevented by pretreatment of the RCME cells with actinomycin D or cycloheximide, suggesting a requirement for protein synthesis in the inhibitory action of dexamethasone. Conditioned media from dexamethasone-treated cells contained a factor that inhibited porcine pancreatic phospholipase A2 (PLA2) in vitro. Transfer of conditioned media from dexamethasone-treated cells to untreated cells did not reduce basal or stimulated prostaglandin release; in contrast, a stimulatory action was consistently observed. Adherence of rabbit peripheral polymorphonuclear leukocytes (PMN) to RCME cells was reduced when the leukocytes were pretreated with 10(-7) M dexamethasone (4 h). However, dexamethasone pretreatment of the RCME cells did not significantly effect granulocyte adhesion. Thus coronary microvascular endothelial cell prostaglandin production is regulated by glucocorticoids, and glucocorticoid-pretreated microvascular endothelial cell release an inhibitor of PLA2 activity into the culture media.(ABSTRACT TRUNCATED AT 250 WORDS)
PubMed, Aug 1, 1995
Treatment of human endothelial cells with cytokines such as interleukin-1, tumor necrosis factor-... more Treatment of human endothelial cells with cytokines such as interleukin-1, tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma induces the expression of specific leukocyte adhesion molecules on the endothelial cell surface. Interfering with either leukocyte adhesion or adhesion protein upregulation is an important therapeutic target as evidenced by the potent anti-inflammatory actions of neutralizing antibodies to these ligands in various animal models and in patients. In the present study we report that cotreatment of human endothelial cells with certain hydroxyflavones and flavanols blocks cytokine-induced ICAM-1, VCAM-1, and E-selectin expression on human endothelial cells. One of the most potent flavones, apigenin, exhibited a dose- and time-dependent, reversible effect on adhesion protein expression as well as inhibiting adhesion protein upregulation at the transcriptional level. Apigenin also inhibited IL-1 alpha-induced prostaglandin synthesis and TNF-alpha-induced IL-6 and IL-8 production, suggesting that the hydroxyflavones may act as general inhibitors of cytokine-induced gene expression. Although apigenin did not inhibit TNF-alpha-induced nuclear translocation of NF-kappa B(p50(NFKB1)/p65(RelA)) we found this flavonoid did inhibit TNF-alpha induced beta-galactosidase activity in SW480 cells stably transfected with a beta-galactosidase reporter construct driven by four NF-kappa B elements, suggesting an action on NF-kappa B transcriptional activation. Adhesion of leukocytes to cytokine-treated endothelial cells was blocked in endothelial cells cotreated with apigenin. Finally, apigenin demonstrated potent anti-inflammatory activity in carrageenan induced rat paw edema and delayed type hypersensitivity in the mouse. We conclude that flavonoids offer important therapeutic potential for the treatment of a variety of inflammatory diseases involving an increase in leukocyte adhesion and trafficking.
Arthritis & Rheumatism, May 1, 1993
To examine the regulation of intercellular adhesion molecule 1 (ICAM-1) in human synovial microva... more To examine the regulation of intercellular adhesion molecule 1 (ICAM-1) in human synovial microvascular endothelial cells (HSE) and human umbilical vein endothelial cells (HUVE) upon exposure to a variety of agents. Cultured endothelial cells were treated with various cytokines alone and in combination. The expression of ICAM-1 was evaluated at several levels, including an investigation of messenger RNA (mRNA) and surface protein expression. Treatment of HSE with interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor alpha (TNF alpha) resulted in minimal increases in ICAM-1 expression, in contrast to findings with HUVE. Incubation of HUVE or HSE with IL-1 or TNF in combination with interferon-gamma (IFN gamma) greatly potentiated the increase in ICAM-1 surface expression. The synergistic effect of IFN gamma and TNF was confirmed by several methods, including a cell-based enzyme-linked immunosorbent assay, fluorescence-activated cell sorting, immunofluorescence staining, and determination of mRNA levels. IFN gamma also augmented the actions of several other agonists on HSE, i.e., IL-4, lipopolysaccharide, and TNF beta/lymphotoxin. Immunoprecipitation of TNF alpha + IFN gamma-stimulated, 125I-labeled HSE cells with anti-ICAM-1 revealed a single 90-kd band, similar in size to ICAM-1 from HUVE treated in an identical manner. Unexpectedly, IFN gamma alone was a potent stimulus for HSE ICAM-1 mRNA synthesis, but was relatively ineffective in HUVE. These studies indicate that IFN gamma plays a critical synergistic role in the regulation of ICAM-1 expression in human synovial endothelial cells.
Journal of Clinical Investigation, Nov 1, 1983
microvessels and isolated and cultured microvessel endothelial cells were prepared from rabbit ca... more microvessels and isolated and cultured microvessel endothelial cells were prepared from rabbit cardiac muscle. Pathways of arachidonic acid metabolism were determined by measurement of exogenous substrate utilization ([1-'4C]arachidonic acid incorporation and release from intact tissue and cells; [1-'4C]prostaglandin H2 (PGH2) metabolism by broken cell preparations) and by quantification of endogenous products (immunoreactive 6-keto-prostaglandin Fla (PGFia,) and prostaglandin E (PGE) release) by selective radioimmunoassay. Rabbit coronary microvessels and derived microvascular endothelial cells (RCME cells) synthesized two major products of the cyclooxygenase pathway: 6-keto-PGFI,, (hydrolytic product of prostaglandin 12) and PGE2. A reduced glutathione requiring PGH-E isomerase was demonstrated in coronary microvessels and RCME cells, but not in rabbit circumflex coronary artery or aorta. In addition, a minor amount of a compound exhibiting similar characteristics to 6-keto-PGE, was found to be produced by microvessels and RCME cells. Measurement of endogenously released prostaglandins indicated that under basal and stimulated conditions, PGE release exceeded that of 6-keto-PGFI,. Microvessels and microvessel endothelial cells derived from cardiac muscle of rabbit exhibit pathways of arachidonate metabolism that are different from those of many large blood vessels and derived endothelial cells.
Journal of Immunology, Feb 15, 1997
Transcriptional activation of vascular cell adhesion molecule-1 gene in vivo and its role in the ... more Transcriptional activation of vascular cell adhesion molecule-1 gene in vivo and its role in the pathophysiology of neutrophilinduced liver injury in murine endotoxin shock.
Journal of Biological Chemistry, Nov 1, 1998
The p65 (RelA) component of nuclear factor-B (NF-B) and the glucocorticoid receptor (GR) mutually... more The p65 (RelA) component of nuclear factor-B (NF-B) and the glucocorticoid receptor (GR) mutually repress each other's ability to activate transcription. Both of these transcriptional activators depend upon the coactivators CREB-binding protein (CBP) and steroid receptor coactivator-1 (SRC-1) for maximal activity. Here we show that increased levels of CBP relieves the inhibition of glucocorticoid-mediated repression of NF-B activity and the NF-B-mediated repression of GR activity. SRC-1 can relieve the NF-B-mediated repression of GR activity. We propose that cross-talk between the p65 component of NF-B and glucocorticoid receptors is due, at least in part, to nuclear competition for limiting amounts of the coactivators CBP and SRC-1, thus providing a novel mechanism for decreasing expression of genes involved in the inflammatory response.
American Journal of Physiology-heart and Circulatory Physiology, Sep 1, 1999
Coordinated adhesive interactions between lymphocyte receptors and endothelial cell adhesion mole... more Coordinated adhesive interactions between lymphocyte receptors and endothelial cell adhesion molecules (CAMs) are a prerequisite for effector cell entry into tumor stroma. Whereas the diminished leukocyte-endothelial cell interactions observed in tumor microvessels have been attributed to a reduced expression of endothelial CAMs, there is no quantitative data bearing on this issue. The dual-radiolabeled monoclonal antibody technique was used to quantify constitutive and tumor necrosis factor (TNF)-␣-induced expression of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), ICAM-2, P-selectin, E-selectin, and platelet-endothelial cell adhesion molecule 1 (PECAM-1) in different vascular beds of normal (C57Bl/6) and RM-1 tumor-bearing mice. When corrected for endothelial surface area, the constitutive expression of selectins in tumor vessels was higher than that observed in other vascular beds. Both constitutive and induced expression of endothelial CAMs in peripheral vascular beds did not differ between normal and tumor-bearing mice. Within the tumor, the magnitude of the upregulation of P-selectin, ICAM-1, and VCAM-1 after TNF-␣ was similar to that within other vascular beds. E-selectin expression in tumors was refractory to TNF-␣, whereas PECAM-1 and ICAM-2 expression were significantly reduced. Our findings suggest that the presence of a solid tumor does not influence endothelial CAM expression in other vascular beds and that the higher density of selectins in nonstimulated tumor vessels may promote the recruitment of rolling leukocytes in this tissue.
Stroke, Jul 1, 1984
Prostaglandin release from microvessels isolated from the rabbit cerebral cortex was determined u... more Prostaglandin release from microvessels isolated from the rabbit cerebral cortex was determined under three different atmospheric conditions: 100% O 2 ("O 2 ") room air, and 95% N 2 =5% CO 2 ("N 2-COj"). Initial studies with homogenates prepared from rabbit cerebral microvessels (RCMV) indicated two pathways of enzymatic PGH 2 transformation, namely PGI 2 synthase and GSH-dependent PGH-PGE isomerase. We measured the release of the principal products of these pathways, 6-keto PGF |a and PGE, from freshly prepared RCMV. The release of 6-keto PGF |a exceeded that of PGE^ in all three protocols. RCMV incubated in "N 2-CO 2 " exhibited a reduction in the release of 6-keto PGF la compared to room air or "O 2 " incubated RCMV, evident at 30-60 min of incubation. No significant differences in the release of PGE 2 were observed among the three incubation protocols. In all three incubation protocols the ratio of 6-keto PGF |a to PGE 2 did not differ during the initial 10 minutes of each incubation. After 30 to 60 min of incubation, this ratio did not change from the "O 2 " or room air treated RCMV, but decreased significantly for the "N 2-CO 2 " treated group. To determine the reversibility of the apparent "N 2-CO 2 " induced decline in 6-keto PGF |a release, microvessels were removed from the nitrogen atmosphere and incubated in room air. Release was measured during the initial 10 min following reintroduction to room air and was compared to room air pretreated controls treated in an identical manner. Complete recovery of 6keto PGF |a production was observed, and an enhanced ratio of 6-keto PGF lo to PGE 2 observed in the "N 2-CO 2 " treated RCMV. In view of the opposing actions of PGI 2 (vasodilator) and PGE 2 (mild vasoconstrictor) on cerebrovascular tone, this study suggests that release of prostaglandins by the microvasculature may participate in the cerebrovascular response to ischemia. In addition, this study suggests that the release of 6keto PGF |n and PGE 2 by cerebral microvessels may be regulated independently.
European Journal of Vascular and Endovascular Surgery, May 1, 2014
WHAT THIS PAPER ADDS Abdominal aortic aneurysms generally enlarge and rupture unless resected or ... more WHAT THIS PAPER ADDS Abdominal aortic aneurysms generally enlarge and rupture unless resected or repaired. To date, pharmacological strategy has proven ineffective in preventing disease progression. In this study, rapamycin proved remarkably effective in preventing progression of established experimental aneurysms. Despite beginning therapy after aneurysm initiation, rapamycin preserved aortic architecture, and attenuated aortic mural angiogenesis and macrophage accumulation. This study adds to the growing body of evidence supporting the use of rapamycin for medical abdominal aortic aneurysm disease management. Objectives: Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease affecting 4e8% of men older than 60 years. No pharmacologic strategies limit disease progression, aneurysm rupture, or aneurysm-related death. We examined the ability of rapamycin to limit the progression of established experimental AAAs. Methods: AAAs were created in 10e12-week-old male C57BL/6J mice via the porcine pancreatic elastase (PPE) infusion method. Beginning 4 days after PPE infusion, mice were treated with rapamycin (5 mg/kg/day) or an equal volume of vehicle for 10 days. AAA progression was monitored by serial ultrasound examination. Aortae were harvested for histological analyses at sacrifice. Results: Three days after PPE infusion, prior to vehicle or rapamycin treatment, aneurysms were enlarging at an equal rate between groups. In the rapamycin group, treatment reduced aortic enlargement by 38%, and 53% at 3 and 10 days, respectively. On histological analysis, medial elastin and smooth muscle cell populations were relatively preserved in the rapamycin group. Rapamycin treatment also reduced mural macrophage density and neoangiogenesis. Conclusion: Rapamycin limits the progression of established experimental aneurysms, increasing the translational potential of mechanistic target of rapamycin-related AAA inhibition strategies.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1997
Integrin activation promotes the survival of endothelial cells undergoing diverse forms of stress... more Integrin activation promotes the survival of endothelial cells undergoing diverse forms of stress. Here we determined the ability of integrins to inhibit DNA strand breakage by bleomycin (BLM), a DNA-cleaving antitumor antibiotic that causes acute endothelial injury and subsequent pulmonary fibrosis. We found that BLM produced DNA breakage in cultured murine lung endothelial cells (MLEC) within 45 min of treatment as measured by DNA sedimentation and in situ labeling of 3'-OH by nick translation (ISNT). Two hours after the removal of BLM, we found a marked but incomplete reduction in DNA strand breakage as measured by ISNT, indicating that the damage was reversible. DNA sedimentation and ISNT demonstrated that strand breakage due to BLM was inhibited in MLEC cultured on fibronectin, and no evidence of breakage was found 2 h after removal of the drug in ISNT experiments. Gelatin, type IV collagen, laminin, and the integrin ligand peptide Gly-Arg-Gly-Asp-Ser-Pro, but not the inact...
American Journal of Physiology-Heart and Circulatory Physiology, 1999
The objective of this study was to determine whether the microvascular responses to ischemia and ... more The objective of this study was to determine whether the microvascular responses to ischemia and reperfusion (I/R) are altered in an animal model of atherosclerosis, the low-density lipoprotein-receptor knockout (LDLr −/−) mouse. Intravital video microscopy was used to monitor venular wall shear rate, leukocytes rolling velocity, the number of rolling, adherent and emigrated leukocytes, and albumin leakage in cremasteric postcapillary venules of wild-type (B6129) and LDLr −/− mice exposed to 60 min of ischemia and 60 min of reperfusion. The postcapillary venules of LDLr −/− mice exhibited two- to threefold larger increments in the number of adherent leukocytes and a more profound albumin leakage response to I/R than venules in wild-type mice. The exaggerated inflammatory responses noted in LDLr −/− mice placed on a normal diet were not exacerbated by a high-cholesterol diet. Treatment of LDLr −/− mice with either a platelet-activating factor (PAF) receptor antagonist (WEB-2086) or a...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1996
Collagen inhibits acute DNA strand breakage and apoptosis in sheep pulmonary artery endothelial c... more Collagen inhibits acute DNA strand breakage and apoptosis in sheep pulmonary artery endothelial cells (SPAEC) treated with lipopolysaccharide (LPS). Here we tested the ability of major basement membrane components, type IV collagen, laminin and fibronectin, and integrin ligands and anti-integrin antibodies to inhibit DNA breakage caused by LPS in SPAEC and BALB/c murine lung endothelial cells (MLEC). In situ labeling of DNA strand breaks with terminal deoxynucleotidyl transferase revealed similar DNA breakage in attached SPAEC and MLEC within 2 h after incubation with 1 microgram LPS/ml. Acute DNA strand breakage was reduced in cells plated on gelatin, type IV collagen, laminin, cellular fibronectin, or plasma fibronectin. DNA breakage was also suppressed by plating cells on surfaces coated with the integrin ligand hexapeptide, GRGDSP (40 micrograms/cm2), but not with GRADSP. LPS-induced DNA strand breakage was inhibited in MLEC plated on surfaces coated with antibodies to murine al...
American Journal of Physiology-Cell Physiology, 1989
Previous studies have shown that treatment of cultured rabbit coronary microvessel endothelial (R... more Previous studies have shown that treatment of cultured rabbit coronary microvessel endothelial (RCME) cells with dexamethasone results in a dose-, time-, and glucocorticoid-dependent inhibition of prostaglandin release. In the present study, the effects of dexamethasone on RCME membrane lipid composition and release of arachidonic acid were examined. This study demonstrated that dexamethasone treatment did not significantly alter the relative distribution of membrane phospholipids but did result in changes of fatty acid composition. There was an increase in saturated and monounsaturated fatty acids and a decrease in polyunsaturated fatty acids. Dexamethasone treatment did not reduce A23187-stimulated arachidonic acid release, despite inhibiting prostaglandin release by 50%. Studies with radiolabeled arachidonic acid suggest that dexamethasone may exert some actions on membrane remodeling, an effect that will require further investigation. Our data strongly suggest that the inhibitor...
American Journal of Physiology-Cell Physiology, 1989
Rabbit coronary microvascular endothelial (RCME) cells synthesize prostaglandin (PG) I2 and PGE2 ... more Rabbit coronary microvascular endothelial (RCME) cells synthesize prostaglandin (PG) I2 and PGE2 in response to stimulation with human thrombin, ATP, and the Ca2+ ionophore, A23187. Replacement of extracellular Na+ with choline or N-methylglucamine reduced thrombin-stimulated PG secretion but did not significantly affect either ATP- or A23187-stimulated PG secretion. Pretreatment of RCME cells with Na+ channel or Na+ -Ca2+ exchange blockers did not alter PG release in response to any of these three agonists. Pretreatment of RCME cells with the specific Na+ -H+ antiport blockers 5-(N-ethyl-N-isopropyl)-amiloride (EIPA, 10 microM) and 5-(N,N-hexamethylene)-amiloride (HMA, 0.1 microM) significantly reduced thrombin but not A23187- or ATP-stimulated PG secretion. Studies with the intracellular pH indicator dye 2,7-bis(carboxyethyl)-5(6)-carboxyfluorescein demonstrated thrombin activation of Na+ -H+ antiport, an effect blocked by either HMA or EIPA. Since manipulations known to inhibit N...
The American journal of pathology, 1994
The elicitation of leukocytes from the circulation to inflamed tissue depends on the activation o... more The elicitation of leukocytes from the circulation to inflamed tissue depends on the activation of both the leukocyte and endothelial cell. In this study we determined the gene expression and secretion patterns for the chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in cytokine- and lipopolysaccharide (LPS)-treated cultured human lung microvascular endothelial cells (HLE). HLE constitutively expressed low levels of MCP-1 and IL-8. Treatment of HLE with a variety of cytokines and LPS up-regulated both IL-8 mRNA expression and release of immunoreactive IL-8 with an order of potency tumor necrosis factor-alpha (TNF-alpha) > IL-1 alpha > LPS, whereas interferon-gamma (IFN-gamma) had no effect on IL-8 mRNA or antigenic levels. However, IFN-gamma, in combination with high doses of IL-1 alpha, resulted in a synergistic increase in IL-8 generation. MCP-1 gene expression and secretion was induced in a dose-dependent manner after IL-1 alpha, TNF-alpha, IFN...
Journal of Surgical Research, 2013
Clinical Cancer Research, 2008
Purpose: Mutations associated with resistance to kinase inhibition are an important mechanism of ... more Purpose: Mutations associated with resistance to kinase inhibition are an important mechanism of intrinsic or acquired loss of clinical efficacy for kinase-targeted therapeutics. We report the prospective discovery of ErbB2 mutations that confer resistance to the small-molecule inhibitor lapatinib. Experimental Design: We did in vitro screening using a randomly mutagenized ErbB2 expression library in Ba/F3 cells, which were dependent on ErbB2 activity for survival and growth. Results: Lapatinib resistance screens identified mutations at 16 different ErbB2 amino acid residues, with 12 mutated amino acids mapping to the kinase domain. Mutations conferring the greatest lapatinib resistance cluster in the NH2-terminal kinase lobe and hinge region. Structural computer modeling studies suggest that lapatinib resistance is caused by multiple mechanisms; including direct steric interference and restriction of conformational flexibility (the inactive state required for lapatinib binding is e...
Allergy, 2004
Eosinophils and the gastrointestinal tract interact in an intimate and enigmatic relationship. Un... more Eosinophils and the gastrointestinal tract interact in an intimate and enigmatic relationship. Under healthy conditions, the presence of eosinophils is limited almost exclusively to the digestive tract mucosa where they exert several effector and immunoregulatory functions. While their precise function in the gastrointestinal tract is not completely understood, it is likely that, together with different T cell subsets, eosinophils are involved in maintaining the immunologic homeostastis across the mucosal barrier under resting conditions. Eosinophils also play a role in several inflammatory conditions, such as intestinal infections, hypersensitivity reactions, primary eosinophilic inflammations and several other chronic intestinal disorders. Depending on the responsible trigger, their effects may be beneficial or detrimental. Here, we discuss the available information regarding the physiological and pathological functions of eosinophils within the gastrointestinal tract.
Microcirculation, Feb 1, 2010
Objective-To test the hypothesis that rapamycin inhibits induced microvascular hyperpermeability ... more Objective-To test the hypothesis that rapamycin inhibits induced microvascular hyperpermeability directly in vivo. Methods-Male golden Syrian hamsters (80-120g) were treated with either rapamycin (at 0.1, 0.5, 2, and 10 mg/kg i.p.) or vehicle at 24 hours and at one hour prior to preparation of the cheek pouch. Caveolin-1 scaffolding (1 mg/kg; positive inhibitory control) was injected i.p. 24 hours prior to the experiment. 10 −8 M vascular endothelial growth factor (VEGF) or 10 −7 M plateletactivating factor (PAF) were topically applied to the cheek pouch. Microvascular permeability and arteriolar diameter were assessed using integrated optical intensity (IOI) and vascular wall imaging, respectively. Results-Rapamycin at 0.1 mg/kg and 0.5 mg/kg significantly reduced VEGF-stimulated mean IOI from 63.0±4.2 to 9.7±5.0 (85% reduction, P<0.001) and 3.6±2.7 (95% reduction, P<0.001), respectively. Rapamycin at 2 mg/kg also lowered VEGF-stimulated hyperpermeability (40% reduction, P<0.05). However, 10 mg/kg rapamycin increased VEGF-induced microvascular hyperpermeability. Rapamycin at 0.5 mg/kg attenuated VEGF-induced vasodilation and PAFinduced hyperpermeability, but did not inhibit PAF-induced vasoconstriction. Conclusions-At therapeutically relevant concentrations, rapamycin inhibits VEGF-and PAFinduced microvascular permeability. This inhibition is 1) a direct effect on the endothelial barrier, and 2) independent of arteriolar vasodilation. Rapamycin at 10 mg/kg stimulates effectors that increase microvascular permeability.
PubMed, Feb 1, 1998
The activation of sphingomyelinase and the generation of ceramide has been proposed to mediate tu... more The activation of sphingomyelinase and the generation of ceramide has been proposed to mediate tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor (NF)-kappaB activation through its second messenger ceramide. Ceramide may also be an important regulator of cell growth, senescence, and apoptosis. Aberrant cell proliferation and apoptosis have been implicated in the rampant fibroblast proliferation and pannus formation characteristic of rheumatoid arthritis. However, the role of TNF-alpha and the sphingomyelinase pathway in the process have not been determined. The objective of this study was to determine whether TNF-alpha activates the sphingomyelin pathway in human synovial fibroblasts (HSF) and the potential role of ceramide in HSF proliferation and apoptosis. Cultured human synovial fibroblasts were stimulated with exogenous TNF-alpha, sphingomyelinase, and ceramide. Apoptosis was assessed by cell morphology and annexin V labeling. NF-kappaB and stress kinase pathway activation were determined by immunoblotting techniques. Sphingomyelinase activation was determined by quantitation of sphingomyelin and ceramide radioactivity in [14C]serine-prelabeled HSF cells. The addition of TNF-alpha (50 ng/ml) to HSF did not elicit detectable sphingomyelinase activation. TNF-alpha was shown to activate NF-kappaB (p65 translocation and degradation of IkappaBalpha) and the stress kinase pathway (phosphorylation of ATF-2, p38, and c-jun). In contrast, exogenous ceramide had no effect on these signaling pathways nor did ceramide stimulate the generation of interleukin-6 or interleukin-8. High concentrations of ceramide (> or =25 micromol/L) were cytotoxic, whereas lower concentrations of ceramide inhibited cell cycle progression. Thus, although TNF-alpha stimulates the NF-kappaB and stress kinase pathways in HSF, these effects of TNF-alpha are not associated with sphingomyelinase turnover or induction of apoptosis.
American Journal of Physiology-cell Physiology, Jun 1, 1986
The effects of dexamethasone on prostaglandin secretion by cultivated rabbit coronary microvascul... more The effects of dexamethasone on prostaglandin secretion by cultivated rabbit coronary microvascular endothelial (RCME) cells were investigated. Incubation of RCME cells with dexamethasone resulted in a time- and concentration-dependent decrease in prostaglandin accumulation in the culture media and reduced basal and A23187-stimulated prostaglandin (PG) E2 and 6-keto-PGF1 alpha release. The maximal effects of dexamethasone (50-80% inhibition) were achieved after 16-18 h of incubation with the steroid at a final concentration of 10(-7) M. The effects of dexamethasone treatment were partially reversed 24 h after removal of the steroid from the culture media. Dexamethasone treatment did not reduce arachidonic acid-stimulated prostaglandin synthesis, indicating that the level of inhibition was proximal to that of cyclooxygenase. The inhibitory effects of dexamethasone could be prevented by pretreatment of the RCME cells with actinomycin D or cycloheximide, suggesting a requirement for protein synthesis in the inhibitory action of dexamethasone. Conditioned media from dexamethasone-treated cells contained a factor that inhibited porcine pancreatic phospholipase A2 (PLA2) in vitro. Transfer of conditioned media from dexamethasone-treated cells to untreated cells did not reduce basal or stimulated prostaglandin release; in contrast, a stimulatory action was consistently observed. Adherence of rabbit peripheral polymorphonuclear leukocytes (PMN) to RCME cells was reduced when the leukocytes were pretreated with 10(-7) M dexamethasone (4 h). However, dexamethasone pretreatment of the RCME cells did not significantly effect granulocyte adhesion. Thus coronary microvascular endothelial cell prostaglandin production is regulated by glucocorticoids, and glucocorticoid-pretreated microvascular endothelial cell release an inhibitor of PLA2 activity into the culture media.(ABSTRACT TRUNCATED AT 250 WORDS)
PubMed, Aug 1, 1995
Treatment of human endothelial cells with cytokines such as interleukin-1, tumor necrosis factor-... more Treatment of human endothelial cells with cytokines such as interleukin-1, tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma induces the expression of specific leukocyte adhesion molecules on the endothelial cell surface. Interfering with either leukocyte adhesion or adhesion protein upregulation is an important therapeutic target as evidenced by the potent anti-inflammatory actions of neutralizing antibodies to these ligands in various animal models and in patients. In the present study we report that cotreatment of human endothelial cells with certain hydroxyflavones and flavanols blocks cytokine-induced ICAM-1, VCAM-1, and E-selectin expression on human endothelial cells. One of the most potent flavones, apigenin, exhibited a dose- and time-dependent, reversible effect on adhesion protein expression as well as inhibiting adhesion protein upregulation at the transcriptional level. Apigenin also inhibited IL-1 alpha-induced prostaglandin synthesis and TNF-alpha-induced IL-6 and IL-8 production, suggesting that the hydroxyflavones may act as general inhibitors of cytokine-induced gene expression. Although apigenin did not inhibit TNF-alpha-induced nuclear translocation of NF-kappa B(p50(NFKB1)/p65(RelA)) we found this flavonoid did inhibit TNF-alpha induced beta-galactosidase activity in SW480 cells stably transfected with a beta-galactosidase reporter construct driven by four NF-kappa B elements, suggesting an action on NF-kappa B transcriptional activation. Adhesion of leukocytes to cytokine-treated endothelial cells was blocked in endothelial cells cotreated with apigenin. Finally, apigenin demonstrated potent anti-inflammatory activity in carrageenan induced rat paw edema and delayed type hypersensitivity in the mouse. We conclude that flavonoids offer important therapeutic potential for the treatment of a variety of inflammatory diseases involving an increase in leukocyte adhesion and trafficking.
Arthritis & Rheumatism, May 1, 1993
To examine the regulation of intercellular adhesion molecule 1 (ICAM-1) in human synovial microva... more To examine the regulation of intercellular adhesion molecule 1 (ICAM-1) in human synovial microvascular endothelial cells (HSE) and human umbilical vein endothelial cells (HUVE) upon exposure to a variety of agents. Cultured endothelial cells were treated with various cytokines alone and in combination. The expression of ICAM-1 was evaluated at several levels, including an investigation of messenger RNA (mRNA) and surface protein expression. Treatment of HSE with interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor alpha (TNF alpha) resulted in minimal increases in ICAM-1 expression, in contrast to findings with HUVE. Incubation of HUVE or HSE with IL-1 or TNF in combination with interferon-gamma (IFN gamma) greatly potentiated the increase in ICAM-1 surface expression. The synergistic effect of IFN gamma and TNF was confirmed by several methods, including a cell-based enzyme-linked immunosorbent assay, fluorescence-activated cell sorting, immunofluorescence staining, and determination of mRNA levels. IFN gamma also augmented the actions of several other agonists on HSE, i.e., IL-4, lipopolysaccharide, and TNF beta/lymphotoxin. Immunoprecipitation of TNF alpha + IFN gamma-stimulated, 125I-labeled HSE cells with anti-ICAM-1 revealed a single 90-kd band, similar in size to ICAM-1 from HUVE treated in an identical manner. Unexpectedly, IFN gamma alone was a potent stimulus for HSE ICAM-1 mRNA synthesis, but was relatively ineffective in HUVE. These studies indicate that IFN gamma plays a critical synergistic role in the regulation of ICAM-1 expression in human synovial endothelial cells.
Journal of Clinical Investigation, Nov 1, 1983
microvessels and isolated and cultured microvessel endothelial cells were prepared from rabbit ca... more microvessels and isolated and cultured microvessel endothelial cells were prepared from rabbit cardiac muscle. Pathways of arachidonic acid metabolism were determined by measurement of exogenous substrate utilization ([1-'4C]arachidonic acid incorporation and release from intact tissue and cells; [1-'4C]prostaglandin H2 (PGH2) metabolism by broken cell preparations) and by quantification of endogenous products (immunoreactive 6-keto-prostaglandin Fla (PGFia,) and prostaglandin E (PGE) release) by selective radioimmunoassay. Rabbit coronary microvessels and derived microvascular endothelial cells (RCME cells) synthesized two major products of the cyclooxygenase pathway: 6-keto-PGFI,, (hydrolytic product of prostaglandin 12) and PGE2. A reduced glutathione requiring PGH-E isomerase was demonstrated in coronary microvessels and RCME cells, but not in rabbit circumflex coronary artery or aorta. In addition, a minor amount of a compound exhibiting similar characteristics to 6-keto-PGE, was found to be produced by microvessels and RCME cells. Measurement of endogenously released prostaglandins indicated that under basal and stimulated conditions, PGE release exceeded that of 6-keto-PGFI,. Microvessels and microvessel endothelial cells derived from cardiac muscle of rabbit exhibit pathways of arachidonate metabolism that are different from those of many large blood vessels and derived endothelial cells.
Journal of Immunology, Feb 15, 1997
Transcriptional activation of vascular cell adhesion molecule-1 gene in vivo and its role in the ... more Transcriptional activation of vascular cell adhesion molecule-1 gene in vivo and its role in the pathophysiology of neutrophilinduced liver injury in murine endotoxin shock.
Journal of Biological Chemistry, Nov 1, 1998
The p65 (RelA) component of nuclear factor-B (NF-B) and the glucocorticoid receptor (GR) mutually... more The p65 (RelA) component of nuclear factor-B (NF-B) and the glucocorticoid receptor (GR) mutually repress each other's ability to activate transcription. Both of these transcriptional activators depend upon the coactivators CREB-binding protein (CBP) and steroid receptor coactivator-1 (SRC-1) for maximal activity. Here we show that increased levels of CBP relieves the inhibition of glucocorticoid-mediated repression of NF-B activity and the NF-B-mediated repression of GR activity. SRC-1 can relieve the NF-B-mediated repression of GR activity. We propose that cross-talk between the p65 component of NF-B and glucocorticoid receptors is due, at least in part, to nuclear competition for limiting amounts of the coactivators CBP and SRC-1, thus providing a novel mechanism for decreasing expression of genes involved in the inflammatory response.
American Journal of Physiology-heart and Circulatory Physiology, Sep 1, 1999
Coordinated adhesive interactions between lymphocyte receptors and endothelial cell adhesion mole... more Coordinated adhesive interactions between lymphocyte receptors and endothelial cell adhesion molecules (CAMs) are a prerequisite for effector cell entry into tumor stroma. Whereas the diminished leukocyte-endothelial cell interactions observed in tumor microvessels have been attributed to a reduced expression of endothelial CAMs, there is no quantitative data bearing on this issue. The dual-radiolabeled monoclonal antibody technique was used to quantify constitutive and tumor necrosis factor (TNF)-␣-induced expression of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), ICAM-2, P-selectin, E-selectin, and platelet-endothelial cell adhesion molecule 1 (PECAM-1) in different vascular beds of normal (C57Bl/6) and RM-1 tumor-bearing mice. When corrected for endothelial surface area, the constitutive expression of selectins in tumor vessels was higher than that observed in other vascular beds. Both constitutive and induced expression of endothelial CAMs in peripheral vascular beds did not differ between normal and tumor-bearing mice. Within the tumor, the magnitude of the upregulation of P-selectin, ICAM-1, and VCAM-1 after TNF-␣ was similar to that within other vascular beds. E-selectin expression in tumors was refractory to TNF-␣, whereas PECAM-1 and ICAM-2 expression were significantly reduced. Our findings suggest that the presence of a solid tumor does not influence endothelial CAM expression in other vascular beds and that the higher density of selectins in nonstimulated tumor vessels may promote the recruitment of rolling leukocytes in this tissue.
Stroke, Jul 1, 1984
Prostaglandin release from microvessels isolated from the rabbit cerebral cortex was determined u... more Prostaglandin release from microvessels isolated from the rabbit cerebral cortex was determined under three different atmospheric conditions: 100% O 2 ("O 2 ") room air, and 95% N 2 =5% CO 2 ("N 2-COj"). Initial studies with homogenates prepared from rabbit cerebral microvessels (RCMV) indicated two pathways of enzymatic PGH 2 transformation, namely PGI 2 synthase and GSH-dependent PGH-PGE isomerase. We measured the release of the principal products of these pathways, 6-keto PGF |a and PGE, from freshly prepared RCMV. The release of 6-keto PGF |a exceeded that of PGE^ in all three protocols. RCMV incubated in "N 2-CO 2 " exhibited a reduction in the release of 6-keto PGF la compared to room air or "O 2 " incubated RCMV, evident at 30-60 min of incubation. No significant differences in the release of PGE 2 were observed among the three incubation protocols. In all three incubation protocols the ratio of 6-keto PGF |a to PGE 2 did not differ during the initial 10 minutes of each incubation. After 30 to 60 min of incubation, this ratio did not change from the "O 2 " or room air treated RCMV, but decreased significantly for the "N 2-CO 2 " treated group. To determine the reversibility of the apparent "N 2-CO 2 " induced decline in 6-keto PGF |a release, microvessels were removed from the nitrogen atmosphere and incubated in room air. Release was measured during the initial 10 min following reintroduction to room air and was compared to room air pretreated controls treated in an identical manner. Complete recovery of 6keto PGF |a production was observed, and an enhanced ratio of 6-keto PGF lo to PGE 2 observed in the "N 2-CO 2 " treated RCMV. In view of the opposing actions of PGI 2 (vasodilator) and PGE 2 (mild vasoconstrictor) on cerebrovascular tone, this study suggests that release of prostaglandins by the microvasculature may participate in the cerebrovascular response to ischemia. In addition, this study suggests that the release of 6keto PGF |n and PGE 2 by cerebral microvessels may be regulated independently.
European Journal of Vascular and Endovascular Surgery, May 1, 2014
WHAT THIS PAPER ADDS Abdominal aortic aneurysms generally enlarge and rupture unless resected or ... more WHAT THIS PAPER ADDS Abdominal aortic aneurysms generally enlarge and rupture unless resected or repaired. To date, pharmacological strategy has proven ineffective in preventing disease progression. In this study, rapamycin proved remarkably effective in preventing progression of established experimental aneurysms. Despite beginning therapy after aneurysm initiation, rapamycin preserved aortic architecture, and attenuated aortic mural angiogenesis and macrophage accumulation. This study adds to the growing body of evidence supporting the use of rapamycin for medical abdominal aortic aneurysm disease management. Objectives: Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease affecting 4e8% of men older than 60 years. No pharmacologic strategies limit disease progression, aneurysm rupture, or aneurysm-related death. We examined the ability of rapamycin to limit the progression of established experimental AAAs. Methods: AAAs were created in 10e12-week-old male C57BL/6J mice via the porcine pancreatic elastase (PPE) infusion method. Beginning 4 days after PPE infusion, mice were treated with rapamycin (5 mg/kg/day) or an equal volume of vehicle for 10 days. AAA progression was monitored by serial ultrasound examination. Aortae were harvested for histological analyses at sacrifice. Results: Three days after PPE infusion, prior to vehicle or rapamycin treatment, aneurysms were enlarging at an equal rate between groups. In the rapamycin group, treatment reduced aortic enlargement by 38%, and 53% at 3 and 10 days, respectively. On histological analysis, medial elastin and smooth muscle cell populations were relatively preserved in the rapamycin group. Rapamycin treatment also reduced mural macrophage density and neoangiogenesis. Conclusion: Rapamycin limits the progression of established experimental aneurysms, increasing the translational potential of mechanistic target of rapamycin-related AAA inhibition strategies.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1997
Integrin activation promotes the survival of endothelial cells undergoing diverse forms of stress... more Integrin activation promotes the survival of endothelial cells undergoing diverse forms of stress. Here we determined the ability of integrins to inhibit DNA strand breakage by bleomycin (BLM), a DNA-cleaving antitumor antibiotic that causes acute endothelial injury and subsequent pulmonary fibrosis. We found that BLM produced DNA breakage in cultured murine lung endothelial cells (MLEC) within 45 min of treatment as measured by DNA sedimentation and in situ labeling of 3'-OH by nick translation (ISNT). Two hours after the removal of BLM, we found a marked but incomplete reduction in DNA strand breakage as measured by ISNT, indicating that the damage was reversible. DNA sedimentation and ISNT demonstrated that strand breakage due to BLM was inhibited in MLEC cultured on fibronectin, and no evidence of breakage was found 2 h after removal of the drug in ISNT experiments. Gelatin, type IV collagen, laminin, and the integrin ligand peptide Gly-Arg-Gly-Asp-Ser-Pro, but not the inact...
American Journal of Physiology-Heart and Circulatory Physiology, 1999
The objective of this study was to determine whether the microvascular responses to ischemia and ... more The objective of this study was to determine whether the microvascular responses to ischemia and reperfusion (I/R) are altered in an animal model of atherosclerosis, the low-density lipoprotein-receptor knockout (LDLr −/−) mouse. Intravital video microscopy was used to monitor venular wall shear rate, leukocytes rolling velocity, the number of rolling, adherent and emigrated leukocytes, and albumin leakage in cremasteric postcapillary venules of wild-type (B6129) and LDLr −/− mice exposed to 60 min of ischemia and 60 min of reperfusion. The postcapillary venules of LDLr −/− mice exhibited two- to threefold larger increments in the number of adherent leukocytes and a more profound albumin leakage response to I/R than venules in wild-type mice. The exaggerated inflammatory responses noted in LDLr −/− mice placed on a normal diet were not exacerbated by a high-cholesterol diet. Treatment of LDLr −/− mice with either a platelet-activating factor (PAF) receptor antagonist (WEB-2086) or a...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1996
Collagen inhibits acute DNA strand breakage and apoptosis in sheep pulmonary artery endothelial c... more Collagen inhibits acute DNA strand breakage and apoptosis in sheep pulmonary artery endothelial cells (SPAEC) treated with lipopolysaccharide (LPS). Here we tested the ability of major basement membrane components, type IV collagen, laminin and fibronectin, and integrin ligands and anti-integrin antibodies to inhibit DNA breakage caused by LPS in SPAEC and BALB/c murine lung endothelial cells (MLEC). In situ labeling of DNA strand breaks with terminal deoxynucleotidyl transferase revealed similar DNA breakage in attached SPAEC and MLEC within 2 h after incubation with 1 microgram LPS/ml. Acute DNA strand breakage was reduced in cells plated on gelatin, type IV collagen, laminin, cellular fibronectin, or plasma fibronectin. DNA breakage was also suppressed by plating cells on surfaces coated with the integrin ligand hexapeptide, GRGDSP (40 micrograms/cm2), but not with GRADSP. LPS-induced DNA strand breakage was inhibited in MLEC plated on surfaces coated with antibodies to murine al...
American Journal of Physiology-Cell Physiology, 1989
Previous studies have shown that treatment of cultured rabbit coronary microvessel endothelial (R... more Previous studies have shown that treatment of cultured rabbit coronary microvessel endothelial (RCME) cells with dexamethasone results in a dose-, time-, and glucocorticoid-dependent inhibition of prostaglandin release. In the present study, the effects of dexamethasone on RCME membrane lipid composition and release of arachidonic acid were examined. This study demonstrated that dexamethasone treatment did not significantly alter the relative distribution of membrane phospholipids but did result in changes of fatty acid composition. There was an increase in saturated and monounsaturated fatty acids and a decrease in polyunsaturated fatty acids. Dexamethasone treatment did not reduce A23187-stimulated arachidonic acid release, despite inhibiting prostaglandin release by 50%. Studies with radiolabeled arachidonic acid suggest that dexamethasone may exert some actions on membrane remodeling, an effect that will require further investigation. Our data strongly suggest that the inhibitor...
American Journal of Physiology-Cell Physiology, 1989
Rabbit coronary microvascular endothelial (RCME) cells synthesize prostaglandin (PG) I2 and PGE2 ... more Rabbit coronary microvascular endothelial (RCME) cells synthesize prostaglandin (PG) I2 and PGE2 in response to stimulation with human thrombin, ATP, and the Ca2+ ionophore, A23187. Replacement of extracellular Na+ with choline or N-methylglucamine reduced thrombin-stimulated PG secretion but did not significantly affect either ATP- or A23187-stimulated PG secretion. Pretreatment of RCME cells with Na+ channel or Na+ -Ca2+ exchange blockers did not alter PG release in response to any of these three agonists. Pretreatment of RCME cells with the specific Na+ -H+ antiport blockers 5-(N-ethyl-N-isopropyl)-amiloride (EIPA, 10 microM) and 5-(N,N-hexamethylene)-amiloride (HMA, 0.1 microM) significantly reduced thrombin but not A23187- or ATP-stimulated PG secretion. Studies with the intracellular pH indicator dye 2,7-bis(carboxyethyl)-5(6)-carboxyfluorescein demonstrated thrombin activation of Na+ -H+ antiport, an effect blocked by either HMA or EIPA. Since manipulations known to inhibit N...
The American journal of pathology, 1994
The elicitation of leukocytes from the circulation to inflamed tissue depends on the activation o... more The elicitation of leukocytes from the circulation to inflamed tissue depends on the activation of both the leukocyte and endothelial cell. In this study we determined the gene expression and secretion patterns for the chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in cytokine- and lipopolysaccharide (LPS)-treated cultured human lung microvascular endothelial cells (HLE). HLE constitutively expressed low levels of MCP-1 and IL-8. Treatment of HLE with a variety of cytokines and LPS up-regulated both IL-8 mRNA expression and release of immunoreactive IL-8 with an order of potency tumor necrosis factor-alpha (TNF-alpha) > IL-1 alpha > LPS, whereas interferon-gamma (IFN-gamma) had no effect on IL-8 mRNA or antigenic levels. However, IFN-gamma, in combination with high doses of IL-1 alpha, resulted in a synergistic increase in IL-8 generation. MCP-1 gene expression and secretion was induced in a dose-dependent manner after IL-1 alpha, TNF-alpha, IFN...
Journal of Surgical Research, 2013
Clinical Cancer Research, 2008
Purpose: Mutations associated with resistance to kinase inhibition are an important mechanism of ... more Purpose: Mutations associated with resistance to kinase inhibition are an important mechanism of intrinsic or acquired loss of clinical efficacy for kinase-targeted therapeutics. We report the prospective discovery of ErbB2 mutations that confer resistance to the small-molecule inhibitor lapatinib. Experimental Design: We did in vitro screening using a randomly mutagenized ErbB2 expression library in Ba/F3 cells, which were dependent on ErbB2 activity for survival and growth. Results: Lapatinib resistance screens identified mutations at 16 different ErbB2 amino acid residues, with 12 mutated amino acids mapping to the kinase domain. Mutations conferring the greatest lapatinib resistance cluster in the NH2-terminal kinase lobe and hinge region. Structural computer modeling studies suggest that lapatinib resistance is caused by multiple mechanisms; including direct steric interference and restriction of conformational flexibility (the inactive state required for lapatinib binding is e...
Allergy, 2004
Eosinophils and the gastrointestinal tract interact in an intimate and enigmatic relationship. Un... more Eosinophils and the gastrointestinal tract interact in an intimate and enigmatic relationship. Under healthy conditions, the presence of eosinophils is limited almost exclusively to the digestive tract mucosa where they exert several effector and immunoregulatory functions. While their precise function in the gastrointestinal tract is not completely understood, it is likely that, together with different T cell subsets, eosinophils are involved in maintaining the immunologic homeostastis across the mucosal barrier under resting conditions. Eosinophils also play a role in several inflammatory conditions, such as intestinal infections, hypersensitivity reactions, primary eosinophilic inflammations and several other chronic intestinal disorders. Depending on the responsible trigger, their effects may be beneficial or detrimental. Here, we discuss the available information regarding the physiological and pathological functions of eosinophils within the gastrointestinal tract.