P. Proost - Academia.edu (original) (raw)

Papers by P. Proost

Research paper thumbnail of Antimicrobial peptides from Amaranthus caudatus seeds with sequence homology to the cysteine/glycine-rich domain of chitin-binding proteins

Biochemistry, 1992

Two antimicrobial peptides (Ac-AMP1 and Ac-AMP2) were isolated from seeds of amaranth (Amaranthus... more Two antimicrobial peptides (Ac-AMP1 and Ac-AMP2) were isolated from seeds of amaranth (Amaranthus caudatus), and their physicochemical and biological properties were characterized. On the basis of fast atom bombardment mass spectroscopy, Ac-AMP1 and Ac-AMP2 have monoisotopic molecular masses of 3025 and 3181, respectively. Both proteins have pI values above 10. The amino acid sequence of Ac-AMP1 (29 residues) is identical to that of Ac-AMP2 (30 residues), except that the latter has 1 additional residue at the carboxyl terminus. The sequences are highly homologous to the cysteine/glycine-rich domain occurring in many chitin-binding proteins. Both Ac-AMP1 and Ac-AMP2 bind to chitin in a reversible way. Ac-AMP1 and Ac-AMP2 inhibit the growth of different plant pathogenic fungi at much lower doses than other known antifungal chitin-binding proteins. In addition, they show some activity on Gram-positive bacteria. The antimicrobial effect of Ac-AMP1 and Ac-AMP2 is strongly antagonized by cations.

Research paper thumbnail of BAL neutrophilia in azithromycin-treated lung transplant recipients: Clinical significance

Transplant Immunology, 2015

Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CL... more Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CLAD) after lung transplantation (LTx). It also can be used to treat lymphocytic bronchiolitis, as it decreases the submucosal infiltrating IL-17 positive lymphocytes. Some patients, while receiving azithromycin, (re)develop increased airway neutrophilia, which we hypothesize to result in worse outcome and to be regulated by an IL-17-independent mechanism. LTx recipients, transplanted between 2001 and 2012, were investigated and categorized in a study group of patients with increased broncho-alveolar lavage (BAL) neutrophilia (≥15%) and a matched control group with low BAL neutrophilia (<15%), both groups while already being on azithromycin treatment. CLAD-free and overall survival were compared between groups. Cell differentials and 33 proteins in BAL were analyzed to identify underlying mechanisms. The study group (n=72) demonstrated a significantly lower CLAD-free (p=0.015) and overall survival (p=0.041) compared to the control group (n=37). Absolute BAL neutrophils and eosinophils were increased in the study group, which was paralleled by elevated inflammatory cytokines (IL-1β/IL-1Ra, IL-4 and IL-6) and chemokines (CXCL8/IL-8, CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL11/eotaxin) concentrations compared to the control group (all p<0.05). Patients with elevated airway neutrophilia despite azithromycin, experience worse CLAD-free and overall survival. In these patients, IL-1β might play a central role giving rise to neutrophils, eosinophils, macrophages and B-cells. This provides an opportunity to further investigate the modulation of this pathway.

Research paper thumbnail of Obligatory involvement of CD26/dipeptidyl peptidase IV in the activation of the antiretroviral tripeptide glycylprolylglycinamide (GPG-NH2)

The International Journal of Biochemistry & Cell Biology, 2004

GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds ... more GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds inhibit HIV replication in CEM cell cultures to an equal extent (50% effective concentration: approximately 30 microM). The lymphocyte surface glycoprotein marker CD26, which is identical to dipeptidyl peptidase IV, efficiently converted GPG-NH2 to G-NH2 releasing the dipeptide GP-OH. The closely related QPG-NH2 derivative was also inhibitory to HIV, presumably by the dipeptidyl peptidase IV (DPP IV)-catalyzed release of G-NH2. In contrast, the cyclic pQPG-NH2 derivative in which the glutamine at the amino terminal position of QPG-NH2 was replaced by pyroglutamine and which is resistant to cleavage by purified CD26, was devoid of antiviral activity. CD26 is abundantly expressed on a variety of HIV target cells and is also present in serum of bovine, murine and human origin. The CD26/DPP IV enzymatic activity in serum and in cell suspensions could be efficiently inhibited by the CD26/DPP IV inhibitor L-isoleucinepyrrolidine (IlePyr) with 50% inhibitory concentrations ranging between 20 and 100 microM. When combined in HIV-1-infected cell cultures, IlePyr and Diprotin A (DP-A), another CD26/DPP IV inhibitor, abrogated the antiviral activity of GPG-NH2 but not of G-NH2. Therefore, it was concluded that the anti-HIV drug GPG-NH2 is not active as such, but rather behaves as a prodrug that must be obligatorily cleaved by CD26/DPP IV to G-NH2 to exert its antiretroviral activity. This is the first demonstration of a lymphocyte activation/differentiation marker (i.e. CD26) that plays a direct regulatory and indispensable role in the eventual antiretroviral activity of small synthetic molecules such as the antiretroviral (pro)drug GPG-NH2.

Research paper thumbnail of CD26-processed RANTES(3–68), but not intact RANTES, has potent anti-HIV-1 activity

Antiviral Research, 1998

The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from ... more The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from leukocytes and tumor cells. The highly specific aminopeptidase dipeptidyl peptidase IV (DPP IV), also called CD26, was shown to be responsible for this NH2-terminal truncation of RANTES. Here it is reported that CD26/DPP IV treatment of RANTES enhances its anti-HIV-1 activity. RANTES(3-68) inhibited infection of PBMC by M-tropic HIV-1 strains ten-fold more efficiently than intact RANTES. This difference in antiviral potency between intact and truncated RANTES was even more pronounced (at least 25-fold) in CCR5-transfected cell lines. In HOS.CD4.CCR5 transfected cells, RANTES(1-68) had virtually no anti-HIV-1 activity (IC50 > 130 nM), whereas RANTES(3-68) was a potent inhibitor of HIV-1 replication (1C50: 5.5 nM). The anti-HIV-1 activity of RANTES(1-68) in the different cell types correlated with the expression of CD26. Moreover, the addition of soluble CD26 together with RANTES(1-68) significantly enhanced the antiviral activity of RANTES in HOS.CD4.CCR5 cells (IC50: 13 nM). These observations point to an important role of CD26-mediated processing of RANTES in inhibiting the replication of CCR5-binding HIV strains in HIV-infected persons and in preventing the development of AIDS.

Research paper thumbnail of BAL neutrophilia in azithromycin-treated lung transplant recipients: Clinical significance

Transplant Immunology, 2015

Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CL... more Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CLAD) after lung transplantation (LTx). It also can be used to treat lymphocytic bronchiolitis, as it decreases the submucosal infiltrating IL-17 positive lymphocytes. Some patients, while receiving azithromycin, (re)develop increased airway neutrophilia, which we hypothesize to result in worse outcome and to be regulated by an IL-17-independent mechanism. LTx recipients, transplanted between 2001 and 2012, were investigated and categorized in a study group of patients with increased broncho-alveolar lavage (BAL) neutrophilia (≥15%) and a matched control group with low BAL neutrophilia (<15%), both groups while already being on azithromycin treatment. CLAD-free and overall survival were compared between groups. Cell differentials and 33 proteins in BAL were analyzed to identify underlying mechanisms. The study group (n=72) demonstrated a significantly lower CLAD-free (p=0.015) and overall survival (p=0.041) compared to the control group (n=37). Absolute BAL neutrophils and eosinophils were increased in the study group, which was paralleled by elevated inflammatory cytokines (IL-1β/IL-1Ra, IL-4 and IL-6) and chemokines (CXCL8/IL-8, CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL11/eotaxin) concentrations compared to the control group (all p<0.05). Patients with elevated airway neutrophilia despite azithromycin, experience worse CLAD-free and overall survival. In these patients, IL-1β might play a central role giving rise to neutrophils, eosinophils, macrophages and B-cells. This provides an opportunity to further investigate the modulation of this pathway.

Research paper thumbnail of Chemokine Receptor 3 by Affecting Its Interaction with CC Anti-HIV Activity of Human Eotaxin Chemotactic Potency, But Not the Down-Regulates the Eosinophil CD26/Dipeptidyl-Peptidase IV

Research paper thumbnail of Obligatory involvement of CD26/dipeptidyl peptidase IV in the activation of the antiretroviral tripeptide glycylprolylglycinamide (GPG-NH2)

The International Journal of Biochemistry & Cell Biology, 2004

GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds ... more GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds inhibit HIV replication in CEM cell cultures to an equal extent (50% effective concentration: approximately 30 microM). The lymphocyte surface glycoprotein marker CD26, which is identical to dipeptidyl peptidase IV, efficiently converted GPG-NH2 to G-NH2 releasing the dipeptide GP-OH. The closely related QPG-NH2 derivative was also inhibitory to HIV, presumably by the dipeptidyl peptidase IV (DPP IV)-catalyzed release of G-NH2. In contrast, the cyclic pQPG-NH2 derivative in which the glutamine at the amino terminal position of QPG-NH2 was replaced by pyroglutamine and which is resistant to cleavage by purified CD26, was devoid of antiviral activity. CD26 is abundantly expressed on a variety of HIV target cells and is also present in serum of bovine, murine and human origin. The CD26/DPP IV enzymatic activity in serum and in cell suspensions could be efficiently inhibited by the CD26/DPP IV inhibitor L-isoleucinepyrrolidine (IlePyr) with 50% inhibitory concentrations ranging between 20 and 100 microM. When combined in HIV-1-infected cell cultures, IlePyr and Diprotin A (DP-A), another CD26/DPP IV inhibitor, abrogated the antiviral activity of GPG-NH2 but not of G-NH2. Therefore, it was concluded that the anti-HIV drug GPG-NH2 is not active as such, but rather behaves as a prodrug that must be obligatorily cleaved by CD26/DPP IV to G-NH2 to exert its antiretroviral activity. This is the first demonstration of a lymphocyte activation/differentiation marker (i.e. CD26) that plays a direct regulatory and indispensable role in the eventual antiretroviral activity of small synthetic molecules such as the antiretroviral (pro)drug GPG-NH2.

Research paper thumbnail of C-Terminal Clipping of Chemokine CCL1/I-309 Enhances CCR8-Mediated Intracellular Calcium Release and Anti-Apoptotic Activity

PLoS ONE, 2012

Carboxypeptidase M (CPM) targets the basic amino acids arginine and lysine present at the C-termi... more Carboxypeptidase M (CPM) targets the basic amino acids arginine and lysine present at the C-terminus of peptides or proteins. CPM is thought to be involved in inflammatory processes. This is corroborated by CPM-mediated trimming and modulation of inflammatory factors, and expression of the protease in inflammatory environments. Since the function of CPM in and beyond inflammation remains mainly undefined, the identification of natural substrates can aid in discovering the (patho)physiological role of CPM. CCL1/I-309, with its three C-terminal basic amino acids, forms a potential natural substrate for CPM. CCL1 plays a role not only in inflammation but also in apoptosis, angiogenesis and tumor biology. Enzymatic processing differently impacts the biological activity of chemokines thereby contributing to the complex regulation of the chemokine system. The aim of the present study was to investigate whether (i) CCL1/I-309 is prone to trimming by CPM, and (ii) the biological activity of CCL1 is altered after C-terminal proteolytic processing. CCL1 was identified as a novel substrate for CPM in vitro using mass spectrometry. C-terminal clipping of CCL1 augmented intracellular calcium release mediated by CCR8 but reduced the binding of CCL1 to CCR8. In line with the higher intracellular calcium release, a pronounced increase of the anti-apoptotic activity of CCL1 was observed in the BW5147 cellular model. CCR8 signaling, CCR8 binding and anti-apoptotic activity were unaffected when CPM was exposed to the carboxypeptidase inhibitor DL-2-mercaptomethyl-3-guanidino-ethylthiopropanoic acid. The results of this study suggest that CPM is a likely candidate for the regulation of biological processes relying on the CCL1-CCR8 system. Citation: Denis C, Deiteren K, Mortier A, Tounsi A, Fransen E, et al. (2012) C-Terminal Clipping of Chemokine CCL1/I-309 Enhances CCR8-Mediated Intracellular Calcium Release and Anti-Apoptotic Activity. PLoS ONE 7(3): e34199.

Research paper thumbnail of The LD78  Isoform of MIP-1  Is the Most Potent CC-Chemokine in Inhibiting CCR5-Dependent Human Immunodeficiency Virus Type 1 Replication in Human Macrophages

Journal of Virology, 2001

The CC-chemokines RANTES, macrophage inflammatory protein 1␣ (MIP-1␣), and MIP-1␤ are natural lig... more The CC-chemokines RANTES, macrophage inflammatory protein 1␣ (MIP-1␣), and MIP-1␤ are natural ligands for the CC-chemokine receptor CCR5. MIP-1␣, also known as LD78␣, has an isoform, LD78␤, which was identified as the product of a nonallelic gene. The two isoforms differ in only 3 amino acids. LD78␤ was recently reported to be a much more potent CCR5 agonist than LD78␣ and RANTES in inducing intracellular Ca 2؉ signaling and chemotaxis. CCR5 is expressed by human monocytes/macrophages (M/M) and represents an important coreceptor for macrophage-tropic, CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1) strains to infect the cells. We compared the antiviral activities of LD78␤ and the other CC-chemokines in M/M. LD78␤ at 100 ng/ml almost completely blocked HIV-1 replication, while at the same concentration LD78␣ had only weak antiviral activity. Moreover, when HIV-1 infection in M/M was monitored by a flow cytometric analysis using p24 antigen intracellular staining, LD78␤ proved to be the most antivirally active of the chemokines. RANTES, once described as the most potent chemokine in inhibiting R5 HIV-1 infection, was found to be considerably less active than LD78␤. LD78␤ strongly downregulated CCR5 expression in M/M, thereby explaining its potent antiviral activity.

Research paper thumbnail of Gelatinase B is present in the cerebrospinal fluid during experimental autoimmune encephalomyelitis and cleaves myelin basic protein

Journal of Neuroscience Research, 1993

Gelatinases in inflammatory demyelinating diseases of the central nervous system (CNS) were studi... more Gelatinases in inflammatory demyelinating diseases of the central nervous system (CNS) were studied using actively induced experimental autoimmune encephalomyelitis (EAE) in mice as a model system. Clinical disease scores correlated in time and in intensity with pathology parameters such as cytosis in the cerebrospinal fluid (CSF), inflammatory infiltrates, and demyelination in the CNS. Zymographic analysis was employed to measure gelatinases A and B in the CSF from individual animals. According to their apparent molecular weight (MW), gelatinases A and B appeared with a MW of 65 and 95 kDa, respectively. The 65 kDa form was present in all samples, even in those derived from non-induced animals, whereas the 95 kDa form was present only in samples from animals developing EAE. The levels of 95 and 65 kDa gelatinase correlated with the CSF cytosis. In vitro digestion of myelin basic protein (MBP) with gelatinase B and analysis of the cleavage products by protein sequence analysis pinpointed two cleavage sites in conserved regions of MBP. Gelatinase production within the CNS may constitute an important pathogenic mechanism for both the disruption of the blood-brain barrier and the destruction of myelin, as observed in several neuroinflammatory disorders.

Research paper thumbnail of Isolation and Structure-Bioactivity Characterization of Glycosylated N-Pro-Opiomelanocortin Isoforms

Journal of Neuroendocrinology, 2002

The N-terminal fragment of mouse pro-opiomelanocortin (N-POMC) was isolated from AtT-20 cell-cond... more The N-terminal fragment of mouse pro-opiomelanocortin (N-POMC) was isolated from AtT-20 cell-conditioned medium on the basis of immunoreactivity to an anti-POMC1-50 monoclonal antibody by a concentration step, a cation exchange step, reversed phase high-performance liquid chromatography (HPLC) and size exclusion HPLC. Two groups of N-POMC isoforms with a molecular weight (MW) of approximately 11 kDa and 13 kDa, respectively, were identified by mass spectrometry and N-terminal amino acid sequencing. C-terminal sequencing indicated that 11 kDa isoforms correspond to POMC1-74 and 13 kDa isoforms to POMC1-95. Isoforms from both groups enhanced the prolactin mRNA content (measured by means of TaqMan real-time reverse transcription-polymerase chain reaction) in cultured rat pituitary cell aggregates in a dose-dependent manner, but not all of them showed this activity. POMC1-74 compounds were significantly more potent than POMC1-95 isoforms. The observed effects were abolished by coincubation with the monoclonal anti-POMC1-50 antibody, showing the specificity of this biological action. Incorporation of bromodeoxyuridine into DNA of immunostained lactotrophs was enhanced by only a minor part of the isoforms. Some of these had no effect on prolactin mRNA expression. The N-POMC isoforms appeared to be N- and at least in part O-glycosylated. After enzymatic N-deglycosylation of selected N-POMC isoforms, the stimulatory effect on the prolactin mRNA level was depressed (in case of the POMC1-95 isoforms) or totally abolished (in case of the POMC1-74 isoforms). The present findings show that N-POMC is a mixture of differentially glycosylated isoforms, that the isoforms of POMC1-74 are the biologically more effective forms and that different isoforms induce different biological responses in the same cell population. The data also show the essential role of N-glycosylation in the biological response.

Research paper thumbnail of CC chemokine ligand-2 synergizes with the nonchemokine G protein-coupled receptor ligand fMLP in monocyte chemotaxis, and it cooperates with the TLR ligand LPS via induction of CXCL8

Journal of Leukocyte Biology, 2009

During inflammatory reactions, endogenously produced cytokines and chemokines act in a network an... more During inflammatory reactions, endogenously produced cytokines and chemokines act in a network and interact with hormones and neurotransmitters to regulate host immune responses. These signaling circuitries are even more interfaced during infections, when microbial agonists activate TLR, RLR, and NLR receptors. On the basis of the discovery of synergy between chemokines for neutrophil attraction, we extend here this phenomenon between the chemokine MCP-1/CCL2 and the GPCR ligand fMLP or the TLR4 agonist LPS on monocytes. In fact, the bacterial tripeptide fMLP, but not the cytokines IL-1beta or IFN-gamma, significantly and dose-dependently synergized with CCL2 in monocyte chemotaxis. Furthermore, LPS rapidly induced the expression of IL-8/CXCL8 but not of the CCL2 receptor CCR2 in monocytic cells. In turn, the induced CXCL8 synergized with CCL2 for mononuclear cell chemotaxis, and the chemotactic effect was mediated by CXCR1/CXCR2, because CXCL8 receptor antagonists or antibodies were capable of blocking the synergy, while keeping the responsiveness to CCL2 intact. These data recapitulate in vitro the complexity of innate immune regulation, provide a novel mechanism of enhancing monocyte chemotaxis during bacterial infections with gram-negative bacteria and demonstrate the importance of local contexts in inflammatory and infectious insults.

Research paper thumbnail of Bacterial Lipopolysaccharide Selectively Up-Regulates the Function of the Chemotactic Peptide Receptor Formyl Peptide Receptor 2 in Murine Microglial Cells

The Journal of Immunology, 2002

Receptors for the bacterial chemotactic peptide fMLP are implicated in inflammation and host defe... more Receptors for the bacterial chemotactic peptide fMLP are implicated in inflammation and host defense against microbial infection. We investigated the expression and function of fMLPR in microglial cells, which share characteristics of mononuclear phagocytes and play an important role in proinflammatory responses in the CNS. The expression of the genes encoding formyl peptide receptor (FPR)1 and FPR2, the high- and low-affinity fMLPR, was detected in a murine microglial cell line N9, but these cells did not respond to chemotactic agonists known for these receptors. N9 cells incubated with bacterial LPS increased the expression of fMLPR genes and developed a species of specific, but low-affinity, binding sites for fMLP, in association with marked calcium mobilization and chemotaxis responses to fMLP in a concentration range that typically activated the low-affinity receptor FPR2. In addition, LPS-treated N9 cells were chemoattracted by two FPR2-specific agonists, the HIV-1 envelope-derived V3 peptide, and the 42 aa form of the amyloid beta peptide which is a pathogenic agent in Alzheimer's disease. Primary murine microglial cells also expressed FPR1 and FPR2 genes, but similar to N9 cells, exhibited FPR2-mediated activation only after LPS treatment. In contrast to its effect on the function of FPR2, LPS reduced N9 cell binding and biological responses to the chemokine stromal cell-derived factor-1alpha. Thus, LPS selectively modulates the function of chemoattractant receptors in microglia and may promote host response in inflammatory diseases in the CNS.

Research paper thumbnail of Citrullination of CXCL8 by peptidylarginine deiminase alters receptor usage, prevents proteolysis, and dampens tissue inflammation

Journal of Experimental Medicine, 2008

Research paper thumbnail of The LD78β isoform of MIP-1α is the most potent CCR5 agonist and HIV-1–inhibiting chemokine

Journal of Clinical Investigation, 1999

Research paper thumbnail of … proteins MCP-1 and MCP-2 in human fibroblasts and leukocytes by cytokines and cytokine inducers. Chemical synthesis of MCP-2 and development of a specific RIA

The Journal of …, 1994

... Cytokines and Cytokine Inducers Chemical Synthesis of MCP-2 and Development of a SpecificRIA&... more ... Cytokines and Cytokine Inducers Chemical Synthesis of MCP-2 and Development of a SpecificRIA' Jo Van Damme,* Paul Proost, Willy Put, Sofie Arens, Jean-Pierre Lenaerts, Rent! Conings, Chislain Opdenakker, Hubertine Heremans, and Alfons Bifliau ...

Research paper thumbnail of Human Monocyte Chemotactic Proteins-2 and -3 (MCP-2 and MCP-3) Attract Human Eosinophils and Desensitize the Chemotactic Responses Towards RANTES

Biochemical and Biophysical Research Communications, 1994

When synthetic monocyte chemotactic proteins (MCPs) were tested in a Boyden chamber assay system ... more When synthetic monocyte chemotactic proteins (MCPs) were tested in a Boyden chamber assay system for eosinophil-chemotactic properties using human eosinophils, MCP-3 was found to be a potent and efficient (percentage input migrating cells) attractant with an ED50 near 2-3 nM. MCP-2 was less potent, exhibiting half maximal chemotaxis at 40 nM. Cross desensitization experiments of eosinophil-chemotaxis revealed that both MCP-3 and MCP-2 desensitized autologous responses. In addition, pretreatment of human eosinophils with natural RANTES desensitized chemotaxis towards MCP-3 as well as MCP-2, whereas pretreatment of eosinophils with MCP-3 desensitized, apart from responses to MCP-3, also responses against RANTES and MCP-2. These findings indicate that possibly both MCP-3 and MCP-2 elicit chemotactic responses via the RANTES-receptor on eosinophils.

Research paper thumbnail of CD26-processed RANTES(3–68), but not intact RANTES, has potent anti-HIV-1 activity

Antiviral Research, 1998

The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from ... more The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from leukocytes and tumor cells. The highly specific aminopeptidase dipeptidyl peptidase IV (DPP IV), also called CD26, was shown to be responsible for this NH2-terminal truncation of RANTES. Here it is reported that CD26/DPP IV treatment of RANTES enhances its anti-HIV-1 activity. RANTES(3-68) inhibited infection of PBMC by M-tropic HIV-1 strains ten-fold more efficiently than intact RANTES. This difference in antiviral potency between intact and truncated RANTES was even more pronounced (at least 25-fold) in CCR5-transfected cell lines. In HOS.CD4.CCR5 transfected cells, RANTES(1-68) had virtually no anti-HIV-1 activity (IC50 > 130 nM), whereas RANTES(3-68) was a potent inhibitor of HIV-1 replication (1C50: 5.5 nM). The anti-HIV-1 activity of RANTES(1-68) in the different cell types correlated with the expression of CD26. Moreover, the addition of soluble CD26 together with RANTES(1-68) significantly enhanced the antiviral activity of RANTES in HOS.CD4.CCR5 cells (IC50: 13 nM). These observations point to an important role of CD26-mediated processing of RANTES in inhibiting the replication of CCR5-binding HIV strains in HIV-infected persons and in preventing the development of AIDS.

Research paper thumbnail of Leaves of the Lamiaceae species Glechoma hederacea (ground ivy) contain a lectin that is structurally and evolutionary related to the legume lectins

The Plant Journal, 2003

A novel lectin has been isolated and cloned from leaves of Glechoma hederacea (ground ivy), a typ... more A novel lectin has been isolated and cloned from leaves of Glechoma hederacea (ground ivy), a typical representative of the plant family Lamiaceae. Biochemical analyses indicated that the G. hederacea agglutinin (Gleheda) is a tetrameric protein consisting of four subunits pairwise linked through an interchain disulphide bridge and exhibits a preferential speci®city towards N-acetylgalactosamine. Cloning of the corresponding gene and molecular modeling of the deduced sequence demonstrated that Gleheda shares high sequence similarity with the legume lectins and exhibits the same overall fold and three-dimensional structure as the classical legume lectins. The identi®cation of a soluble and active legume lectin ortholog in G. hederacea not only indicates that the yet unclassi®ed Lamiaceae lectins belong to the same lectin family as the legume lectins, but also sheds a new light on the speci®city, physiological role and evolution of the classical legume lectins.

Research paper thumbnail of Antimicrobial peptides from Amaranthus caudatus seeds with sequence homology to the cysteine/glycine-rich domain of chitin-binding proteins

Biochemistry, 1992

Two antimicrobial peptides (Ac-AMP1 and Ac-AMP2) were isolated from seeds of amaranth (Amaranthus... more Two antimicrobial peptides (Ac-AMP1 and Ac-AMP2) were isolated from seeds of amaranth (Amaranthus caudatus), and their physicochemical and biological properties were characterized. On the basis of fast atom bombardment mass spectroscopy, Ac-AMP1 and Ac-AMP2 have monoisotopic molecular masses of 3025 and 3181, respectively. Both proteins have pI values above 10. The amino acid sequence of Ac-AMP1 (29 residues) is identical to that of Ac-AMP2 (30 residues), except that the latter has 1 additional residue at the carboxyl terminus. The sequences are highly homologous to the cysteine/glycine-rich domain occurring in many chitin-binding proteins. Both Ac-AMP1 and Ac-AMP2 bind to chitin in a reversible way. Ac-AMP1 and Ac-AMP2 inhibit the growth of different plant pathogenic fungi at much lower doses than other known antifungal chitin-binding proteins. In addition, they show some activity on Gram-positive bacteria. The antimicrobial effect of Ac-AMP1 and Ac-AMP2 is strongly antagonized by cations.

Research paper thumbnail of BAL neutrophilia in azithromycin-treated lung transplant recipients: Clinical significance

Transplant Immunology, 2015

Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CL... more Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CLAD) after lung transplantation (LTx). It also can be used to treat lymphocytic bronchiolitis, as it decreases the submucosal infiltrating IL-17 positive lymphocytes. Some patients, while receiving azithromycin, (re)develop increased airway neutrophilia, which we hypothesize to result in worse outcome and to be regulated by an IL-17-independent mechanism. LTx recipients, transplanted between 2001 and 2012, were investigated and categorized in a study group of patients with increased broncho-alveolar lavage (BAL) neutrophilia (≥15%) and a matched control group with low BAL neutrophilia (<15%), both groups while already being on azithromycin treatment. CLAD-free and overall survival were compared between groups. Cell differentials and 33 proteins in BAL were analyzed to identify underlying mechanisms. The study group (n=72) demonstrated a significantly lower CLAD-free (p=0.015) and overall survival (p=0.041) compared to the control group (n=37). Absolute BAL neutrophils and eosinophils were increased in the study group, which was paralleled by elevated inflammatory cytokines (IL-1β/IL-1Ra, IL-4 and IL-6) and chemokines (CXCL8/IL-8, CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL11/eotaxin) concentrations compared to the control group (all p<0.05). Patients with elevated airway neutrophilia despite azithromycin, experience worse CLAD-free and overall survival. In these patients, IL-1β might play a central role giving rise to neutrophils, eosinophils, macrophages and B-cells. This provides an opportunity to further investigate the modulation of this pathway.

Research paper thumbnail of Obligatory involvement of CD26/dipeptidyl peptidase IV in the activation of the antiretroviral tripeptide glycylprolylglycinamide (GPG-NH2)

The International Journal of Biochemistry & Cell Biology, 2004

GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds ... more GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds inhibit HIV replication in CEM cell cultures to an equal extent (50% effective concentration: approximately 30 microM). The lymphocyte surface glycoprotein marker CD26, which is identical to dipeptidyl peptidase IV, efficiently converted GPG-NH2 to G-NH2 releasing the dipeptide GP-OH. The closely related QPG-NH2 derivative was also inhibitory to HIV, presumably by the dipeptidyl peptidase IV (DPP IV)-catalyzed release of G-NH2. In contrast, the cyclic pQPG-NH2 derivative in which the glutamine at the amino terminal position of QPG-NH2 was replaced by pyroglutamine and which is resistant to cleavage by purified CD26, was devoid of antiviral activity. CD26 is abundantly expressed on a variety of HIV target cells and is also present in serum of bovine, murine and human origin. The CD26/DPP IV enzymatic activity in serum and in cell suspensions could be efficiently inhibited by the CD26/DPP IV inhibitor L-isoleucinepyrrolidine (IlePyr) with 50% inhibitory concentrations ranging between 20 and 100 microM. When combined in HIV-1-infected cell cultures, IlePyr and Diprotin A (DP-A), another CD26/DPP IV inhibitor, abrogated the antiviral activity of GPG-NH2 but not of G-NH2. Therefore, it was concluded that the anti-HIV drug GPG-NH2 is not active as such, but rather behaves as a prodrug that must be obligatorily cleaved by CD26/DPP IV to G-NH2 to exert its antiretroviral activity. This is the first demonstration of a lymphocyte activation/differentiation marker (i.e. CD26) that plays a direct regulatory and indispensable role in the eventual antiretroviral activity of small synthetic molecules such as the antiretroviral (pro)drug GPG-NH2.

Research paper thumbnail of CD26-processed RANTES(3–68), but not intact RANTES, has potent anti-HIV-1 activity

Antiviral Research, 1998

The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from ... more The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from leukocytes and tumor cells. The highly specific aminopeptidase dipeptidyl peptidase IV (DPP IV), also called CD26, was shown to be responsible for this NH2-terminal truncation of RANTES. Here it is reported that CD26/DPP IV treatment of RANTES enhances its anti-HIV-1 activity. RANTES(3-68) inhibited infection of PBMC by M-tropic HIV-1 strains ten-fold more efficiently than intact RANTES. This difference in antiviral potency between intact and truncated RANTES was even more pronounced (at least 25-fold) in CCR5-transfected cell lines. In HOS.CD4.CCR5 transfected cells, RANTES(1-68) had virtually no anti-HIV-1 activity (IC50 > 130 nM), whereas RANTES(3-68) was a potent inhibitor of HIV-1 replication (1C50: 5.5 nM). The anti-HIV-1 activity of RANTES(1-68) in the different cell types correlated with the expression of CD26. Moreover, the addition of soluble CD26 together with RANTES(1-68) significantly enhanced the antiviral activity of RANTES in HOS.CD4.CCR5 cells (IC50: 13 nM). These observations point to an important role of CD26-mediated processing of RANTES in inhibiting the replication of CCR5-binding HIV strains in HIV-infected persons and in preventing the development of AIDS.

Research paper thumbnail of BAL neutrophilia in azithromycin-treated lung transplant recipients: Clinical significance

Transplant Immunology, 2015

Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CL... more Azithromycin decreases airway neutrophilia and can prevent chronic lung allograft dysfunction (CLAD) after lung transplantation (LTx). It also can be used to treat lymphocytic bronchiolitis, as it decreases the submucosal infiltrating IL-17 positive lymphocytes. Some patients, while receiving azithromycin, (re)develop increased airway neutrophilia, which we hypothesize to result in worse outcome and to be regulated by an IL-17-independent mechanism. LTx recipients, transplanted between 2001 and 2012, were investigated and categorized in a study group of patients with increased broncho-alveolar lavage (BAL) neutrophilia (≥15%) and a matched control group with low BAL neutrophilia (<15%), both groups while already being on azithromycin treatment. CLAD-free and overall survival were compared between groups. Cell differentials and 33 proteins in BAL were analyzed to identify underlying mechanisms. The study group (n=72) demonstrated a significantly lower CLAD-free (p=0.015) and overall survival (p=0.041) compared to the control group (n=37). Absolute BAL neutrophils and eosinophils were increased in the study group, which was paralleled by elevated inflammatory cytokines (IL-1β/IL-1Ra, IL-4 and IL-6) and chemokines (CXCL8/IL-8, CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL11/eotaxin) concentrations compared to the control group (all p<0.05). Patients with elevated airway neutrophilia despite azithromycin, experience worse CLAD-free and overall survival. In these patients, IL-1β might play a central role giving rise to neutrophils, eosinophils, macrophages and B-cells. This provides an opportunity to further investigate the modulation of this pathway.

Research paper thumbnail of Chemokine Receptor 3 by Affecting Its Interaction with CC Anti-HIV Activity of Human Eotaxin Chemotactic Potency, But Not the Down-Regulates the Eosinophil CD26/Dipeptidyl-Peptidase IV

Research paper thumbnail of Obligatory involvement of CD26/dipeptidyl peptidase IV in the activation of the antiretroviral tripeptide glycylprolylglycinamide (GPG-NH2)

The International Journal of Biochemistry & Cell Biology, 2004

GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds ... more GPG-NH2 and G-NH2 are highly selective antiretroviral agents in cell culture, and both compounds inhibit HIV replication in CEM cell cultures to an equal extent (50% effective concentration: approximately 30 microM). The lymphocyte surface glycoprotein marker CD26, which is identical to dipeptidyl peptidase IV, efficiently converted GPG-NH2 to G-NH2 releasing the dipeptide GP-OH. The closely related QPG-NH2 derivative was also inhibitory to HIV, presumably by the dipeptidyl peptidase IV (DPP IV)-catalyzed release of G-NH2. In contrast, the cyclic pQPG-NH2 derivative in which the glutamine at the amino terminal position of QPG-NH2 was replaced by pyroglutamine and which is resistant to cleavage by purified CD26, was devoid of antiviral activity. CD26 is abundantly expressed on a variety of HIV target cells and is also present in serum of bovine, murine and human origin. The CD26/DPP IV enzymatic activity in serum and in cell suspensions could be efficiently inhibited by the CD26/DPP IV inhibitor L-isoleucinepyrrolidine (IlePyr) with 50% inhibitory concentrations ranging between 20 and 100 microM. When combined in HIV-1-infected cell cultures, IlePyr and Diprotin A (DP-A), another CD26/DPP IV inhibitor, abrogated the antiviral activity of GPG-NH2 but not of G-NH2. Therefore, it was concluded that the anti-HIV drug GPG-NH2 is not active as such, but rather behaves as a prodrug that must be obligatorily cleaved by CD26/DPP IV to G-NH2 to exert its antiretroviral activity. This is the first demonstration of a lymphocyte activation/differentiation marker (i.e. CD26) that plays a direct regulatory and indispensable role in the eventual antiretroviral activity of small synthetic molecules such as the antiretroviral (pro)drug GPG-NH2.

Research paper thumbnail of C-Terminal Clipping of Chemokine CCL1/I-309 Enhances CCR8-Mediated Intracellular Calcium Release and Anti-Apoptotic Activity

PLoS ONE, 2012

Carboxypeptidase M (CPM) targets the basic amino acids arginine and lysine present at the C-termi... more Carboxypeptidase M (CPM) targets the basic amino acids arginine and lysine present at the C-terminus of peptides or proteins. CPM is thought to be involved in inflammatory processes. This is corroborated by CPM-mediated trimming and modulation of inflammatory factors, and expression of the protease in inflammatory environments. Since the function of CPM in and beyond inflammation remains mainly undefined, the identification of natural substrates can aid in discovering the (patho)physiological role of CPM. CCL1/I-309, with its three C-terminal basic amino acids, forms a potential natural substrate for CPM. CCL1 plays a role not only in inflammation but also in apoptosis, angiogenesis and tumor biology. Enzymatic processing differently impacts the biological activity of chemokines thereby contributing to the complex regulation of the chemokine system. The aim of the present study was to investigate whether (i) CCL1/I-309 is prone to trimming by CPM, and (ii) the biological activity of CCL1 is altered after C-terminal proteolytic processing. CCL1 was identified as a novel substrate for CPM in vitro using mass spectrometry. C-terminal clipping of CCL1 augmented intracellular calcium release mediated by CCR8 but reduced the binding of CCL1 to CCR8. In line with the higher intracellular calcium release, a pronounced increase of the anti-apoptotic activity of CCL1 was observed in the BW5147 cellular model. CCR8 signaling, CCR8 binding and anti-apoptotic activity were unaffected when CPM was exposed to the carboxypeptidase inhibitor DL-2-mercaptomethyl-3-guanidino-ethylthiopropanoic acid. The results of this study suggest that CPM is a likely candidate for the regulation of biological processes relying on the CCL1-CCR8 system. Citation: Denis C, Deiteren K, Mortier A, Tounsi A, Fransen E, et al. (2012) C-Terminal Clipping of Chemokine CCL1/I-309 Enhances CCR8-Mediated Intracellular Calcium Release and Anti-Apoptotic Activity. PLoS ONE 7(3): e34199.

Research paper thumbnail of The LD78  Isoform of MIP-1  Is the Most Potent CC-Chemokine in Inhibiting CCR5-Dependent Human Immunodeficiency Virus Type 1 Replication in Human Macrophages

Journal of Virology, 2001

The CC-chemokines RANTES, macrophage inflammatory protein 1␣ (MIP-1␣), and MIP-1␤ are natural lig... more The CC-chemokines RANTES, macrophage inflammatory protein 1␣ (MIP-1␣), and MIP-1␤ are natural ligands for the CC-chemokine receptor CCR5. MIP-1␣, also known as LD78␣, has an isoform, LD78␤, which was identified as the product of a nonallelic gene. The two isoforms differ in only 3 amino acids. LD78␤ was recently reported to be a much more potent CCR5 agonist than LD78␣ and RANTES in inducing intracellular Ca 2؉ signaling and chemotaxis. CCR5 is expressed by human monocytes/macrophages (M/M) and represents an important coreceptor for macrophage-tropic, CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1) strains to infect the cells. We compared the antiviral activities of LD78␤ and the other CC-chemokines in M/M. LD78␤ at 100 ng/ml almost completely blocked HIV-1 replication, while at the same concentration LD78␣ had only weak antiviral activity. Moreover, when HIV-1 infection in M/M was monitored by a flow cytometric analysis using p24 antigen intracellular staining, LD78␤ proved to be the most antivirally active of the chemokines. RANTES, once described as the most potent chemokine in inhibiting R5 HIV-1 infection, was found to be considerably less active than LD78␤. LD78␤ strongly downregulated CCR5 expression in M/M, thereby explaining its potent antiviral activity.

Research paper thumbnail of Gelatinase B is present in the cerebrospinal fluid during experimental autoimmune encephalomyelitis and cleaves myelin basic protein

Journal of Neuroscience Research, 1993

Gelatinases in inflammatory demyelinating diseases of the central nervous system (CNS) were studi... more Gelatinases in inflammatory demyelinating diseases of the central nervous system (CNS) were studied using actively induced experimental autoimmune encephalomyelitis (EAE) in mice as a model system. Clinical disease scores correlated in time and in intensity with pathology parameters such as cytosis in the cerebrospinal fluid (CSF), inflammatory infiltrates, and demyelination in the CNS. Zymographic analysis was employed to measure gelatinases A and B in the CSF from individual animals. According to their apparent molecular weight (MW), gelatinases A and B appeared with a MW of 65 and 95 kDa, respectively. The 65 kDa form was present in all samples, even in those derived from non-induced animals, whereas the 95 kDa form was present only in samples from animals developing EAE. The levels of 95 and 65 kDa gelatinase correlated with the CSF cytosis. In vitro digestion of myelin basic protein (MBP) with gelatinase B and analysis of the cleavage products by protein sequence analysis pinpointed two cleavage sites in conserved regions of MBP. Gelatinase production within the CNS may constitute an important pathogenic mechanism for both the disruption of the blood-brain barrier and the destruction of myelin, as observed in several neuroinflammatory disorders.

Research paper thumbnail of Isolation and Structure-Bioactivity Characterization of Glycosylated N-Pro-Opiomelanocortin Isoforms

Journal of Neuroendocrinology, 2002

The N-terminal fragment of mouse pro-opiomelanocortin (N-POMC) was isolated from AtT-20 cell-cond... more The N-terminal fragment of mouse pro-opiomelanocortin (N-POMC) was isolated from AtT-20 cell-conditioned medium on the basis of immunoreactivity to an anti-POMC1-50 monoclonal antibody by a concentration step, a cation exchange step, reversed phase high-performance liquid chromatography (HPLC) and size exclusion HPLC. Two groups of N-POMC isoforms with a molecular weight (MW) of approximately 11 kDa and 13 kDa, respectively, were identified by mass spectrometry and N-terminal amino acid sequencing. C-terminal sequencing indicated that 11 kDa isoforms correspond to POMC1-74 and 13 kDa isoforms to POMC1-95. Isoforms from both groups enhanced the prolactin mRNA content (measured by means of TaqMan real-time reverse transcription-polymerase chain reaction) in cultured rat pituitary cell aggregates in a dose-dependent manner, but not all of them showed this activity. POMC1-74 compounds were significantly more potent than POMC1-95 isoforms. The observed effects were abolished by coincubation with the monoclonal anti-POMC1-50 antibody, showing the specificity of this biological action. Incorporation of bromodeoxyuridine into DNA of immunostained lactotrophs was enhanced by only a minor part of the isoforms. Some of these had no effect on prolactin mRNA expression. The N-POMC isoforms appeared to be N- and at least in part O-glycosylated. After enzymatic N-deglycosylation of selected N-POMC isoforms, the stimulatory effect on the prolactin mRNA level was depressed (in case of the POMC1-95 isoforms) or totally abolished (in case of the POMC1-74 isoforms). The present findings show that N-POMC is a mixture of differentially glycosylated isoforms, that the isoforms of POMC1-74 are the biologically more effective forms and that different isoforms induce different biological responses in the same cell population. The data also show the essential role of N-glycosylation in the biological response.

Research paper thumbnail of CC chemokine ligand-2 synergizes with the nonchemokine G protein-coupled receptor ligand fMLP in monocyte chemotaxis, and it cooperates with the TLR ligand LPS via induction of CXCL8

Journal of Leukocyte Biology, 2009

During inflammatory reactions, endogenously produced cytokines and chemokines act in a network an... more During inflammatory reactions, endogenously produced cytokines and chemokines act in a network and interact with hormones and neurotransmitters to regulate host immune responses. These signaling circuitries are even more interfaced during infections, when microbial agonists activate TLR, RLR, and NLR receptors. On the basis of the discovery of synergy between chemokines for neutrophil attraction, we extend here this phenomenon between the chemokine MCP-1/CCL2 and the GPCR ligand fMLP or the TLR4 agonist LPS on monocytes. In fact, the bacterial tripeptide fMLP, but not the cytokines IL-1beta or IFN-gamma, significantly and dose-dependently synergized with CCL2 in monocyte chemotaxis. Furthermore, LPS rapidly induced the expression of IL-8/CXCL8 but not of the CCL2 receptor CCR2 in monocytic cells. In turn, the induced CXCL8 synergized with CCL2 for mononuclear cell chemotaxis, and the chemotactic effect was mediated by CXCR1/CXCR2, because CXCL8 receptor antagonists or antibodies were capable of blocking the synergy, while keeping the responsiveness to CCL2 intact. These data recapitulate in vitro the complexity of innate immune regulation, provide a novel mechanism of enhancing monocyte chemotaxis during bacterial infections with gram-negative bacteria and demonstrate the importance of local contexts in inflammatory and infectious insults.

Research paper thumbnail of Bacterial Lipopolysaccharide Selectively Up-Regulates the Function of the Chemotactic Peptide Receptor Formyl Peptide Receptor 2 in Murine Microglial Cells

The Journal of Immunology, 2002

Receptors for the bacterial chemotactic peptide fMLP are implicated in inflammation and host defe... more Receptors for the bacterial chemotactic peptide fMLP are implicated in inflammation and host defense against microbial infection. We investigated the expression and function of fMLPR in microglial cells, which share characteristics of mononuclear phagocytes and play an important role in proinflammatory responses in the CNS. The expression of the genes encoding formyl peptide receptor (FPR)1 and FPR2, the high- and low-affinity fMLPR, was detected in a murine microglial cell line N9, but these cells did not respond to chemotactic agonists known for these receptors. N9 cells incubated with bacterial LPS increased the expression of fMLPR genes and developed a species of specific, but low-affinity, binding sites for fMLP, in association with marked calcium mobilization and chemotaxis responses to fMLP in a concentration range that typically activated the low-affinity receptor FPR2. In addition, LPS-treated N9 cells were chemoattracted by two FPR2-specific agonists, the HIV-1 envelope-derived V3 peptide, and the 42 aa form of the amyloid beta peptide which is a pathogenic agent in Alzheimer's disease. Primary murine microglial cells also expressed FPR1 and FPR2 genes, but similar to N9 cells, exhibited FPR2-mediated activation only after LPS treatment. In contrast to its effect on the function of FPR2, LPS reduced N9 cell binding and biological responses to the chemokine stromal cell-derived factor-1alpha. Thus, LPS selectively modulates the function of chemoattractant receptors in microglia and may promote host response in inflammatory diseases in the CNS.

Research paper thumbnail of Citrullination of CXCL8 by peptidylarginine deiminase alters receptor usage, prevents proteolysis, and dampens tissue inflammation

Journal of Experimental Medicine, 2008

Research paper thumbnail of The LD78β isoform of MIP-1α is the most potent CCR5 agonist and HIV-1–inhibiting chemokine

Journal of Clinical Investigation, 1999

Research paper thumbnail of … proteins MCP-1 and MCP-2 in human fibroblasts and leukocytes by cytokines and cytokine inducers. Chemical synthesis of MCP-2 and development of a specific RIA

The Journal of …, 1994

... Cytokines and Cytokine Inducers Chemical Synthesis of MCP-2 and Development of a SpecificRIA&... more ... Cytokines and Cytokine Inducers Chemical Synthesis of MCP-2 and Development of a SpecificRIA' Jo Van Damme,* Paul Proost, Willy Put, Sofie Arens, Jean-Pierre Lenaerts, Rent! Conings, Chislain Opdenakker, Hubertine Heremans, and Alfons Bifliau ...

Research paper thumbnail of Human Monocyte Chemotactic Proteins-2 and -3 (MCP-2 and MCP-3) Attract Human Eosinophils and Desensitize the Chemotactic Responses Towards RANTES

Biochemical and Biophysical Research Communications, 1994

When synthetic monocyte chemotactic proteins (MCPs) were tested in a Boyden chamber assay system ... more When synthetic monocyte chemotactic proteins (MCPs) were tested in a Boyden chamber assay system for eosinophil-chemotactic properties using human eosinophils, MCP-3 was found to be a potent and efficient (percentage input migrating cells) attractant with an ED50 near 2-3 nM. MCP-2 was less potent, exhibiting half maximal chemotaxis at 40 nM. Cross desensitization experiments of eosinophil-chemotaxis revealed that both MCP-3 and MCP-2 desensitized autologous responses. In addition, pretreatment of human eosinophils with natural RANTES desensitized chemotaxis towards MCP-3 as well as MCP-2, whereas pretreatment of eosinophils with MCP-3 desensitized, apart from responses to MCP-3, also responses against RANTES and MCP-2. These findings indicate that possibly both MCP-3 and MCP-2 elicit chemotactic responses via the RANTES-receptor on eosinophils.

Research paper thumbnail of CD26-processed RANTES(3–68), but not intact RANTES, has potent anti-HIV-1 activity

Antiviral Research, 1998

The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from ... more The natural CC-chemokine RANTES(3-68), missing two NH2-terminal residues, has been isolated from leukocytes and tumor cells. The highly specific aminopeptidase dipeptidyl peptidase IV (DPP IV), also called CD26, was shown to be responsible for this NH2-terminal truncation of RANTES. Here it is reported that CD26/DPP IV treatment of RANTES enhances its anti-HIV-1 activity. RANTES(3-68) inhibited infection of PBMC by M-tropic HIV-1 strains ten-fold more efficiently than intact RANTES. This difference in antiviral potency between intact and truncated RANTES was even more pronounced (at least 25-fold) in CCR5-transfected cell lines. In HOS.CD4.CCR5 transfected cells, RANTES(1-68) had virtually no anti-HIV-1 activity (IC50 > 130 nM), whereas RANTES(3-68) was a potent inhibitor of HIV-1 replication (1C50: 5.5 nM). The anti-HIV-1 activity of RANTES(1-68) in the different cell types correlated with the expression of CD26. Moreover, the addition of soluble CD26 together with RANTES(1-68) significantly enhanced the antiviral activity of RANTES in HOS.CD4.CCR5 cells (IC50: 13 nM). These observations point to an important role of CD26-mediated processing of RANTES in inhibiting the replication of CCR5-binding HIV strains in HIV-infected persons and in preventing the development of AIDS.

Research paper thumbnail of Leaves of the Lamiaceae species Glechoma hederacea (ground ivy) contain a lectin that is structurally and evolutionary related to the legume lectins

The Plant Journal, 2003

A novel lectin has been isolated and cloned from leaves of Glechoma hederacea (ground ivy), a typ... more A novel lectin has been isolated and cloned from leaves of Glechoma hederacea (ground ivy), a typical representative of the plant family Lamiaceae. Biochemical analyses indicated that the G. hederacea agglutinin (Gleheda) is a tetrameric protein consisting of four subunits pairwise linked through an interchain disulphide bridge and exhibits a preferential speci®city towards N-acetylgalactosamine. Cloning of the corresponding gene and molecular modeling of the deduced sequence demonstrated that Gleheda shares high sequence similarity with the legume lectins and exhibits the same overall fold and three-dimensional structure as the classical legume lectins. The identi®cation of a soluble and active legume lectin ortholog in G. hederacea not only indicates that the yet unclassi®ed Lamiaceae lectins belong to the same lectin family as the legume lectins, but also sheds a new light on the speci®city, physiological role and evolution of the classical legume lectins.