Gregg Silverman | New York University (original) (raw)

Papers by Gregg Silverman

The Journal of clinical investigation, 2006

Antagonists to alpha4 integrin show promise for several autoimmune and inflammatory diseases but ... more Antagonists to alpha4 integrin show promise for several autoimmune and inflammatory diseases but may exhibit mechanism-based toxicities. We tested the capacity of blockade of alpha4 integrin signaling to perturb functions involved in inflammation, while limiting potential adverse effects. We generated and characterized mice bearing a Y991A mutation in alpha4 integrin [alpha4(Y991A) mice], which blocks paxillin binding and inhibits alpha4 integrin signals that support leukocyte migration. In contrast to the embryonic-lethal phenotype of alpha4 integrin-null mice, mice bearing the alpha4(Y991A) mutation were viable and fertile; however, they exhibited defective recruitment of mononuclear leukocytes into thioglycollate-induced peritonitis. Alpha4 integrins are essential for definitive hematopoiesis; however, the alpha4(Y991A) mice had intact lymphohematopoiesis and, with the exception of reduced Peyer's patches, normal architecture and cellularity of secondary lymphoid tissues. We ...

Discovery medicine, 2015

Autoimmune diseases arise from aberrant activation of immune cells directed against endogenous au... more Autoimmune diseases arise from aberrant activation of immune cells directed against endogenous autoantigens expressed throughout the human body. While the initiating triggers remain poorly understood, the self-perpetuating phase of these diseases is directly linked to the ongoing recruitment of inflammatory cells that traffic to the affected anatomical sites. T lymphocytes are prominent drivers of many autoimmune diseases and the targeted trafficking of these cells to infiltrate the affected organs is often a common denominator. The regulation of T cell trafficking involves the coordinated expression of specific patterns of chemokines and the reciprocal expression of cognate chemokine receptors on T cell membranes. Thereby, chemokines direct the specific trafficking of a wide array of responsive activated immune cells. Specific patterns of chemokine receptor expression can correlate with disease activity in an autoimmune disease, confirming the importance of further characterizing t...

CSH protocols, 2007

INTRODUCTIONThere are several ways to quantitate solutions of nucleic acids. If the solution is p... more INTRODUCTIONThere are several ways to quantitate solutions of nucleic acids. If the solution is pure, one can use a spectrophotometer to measure the amount of ultraviolet radiation absorbed by the bases. DNA can also be quantified by measuring the UV-induced emission of fluorescence from intercalated ethidium bromide. This method is useful if there is not enough DNA to quantify with a spectrophotometer, or if the DNA solution is contaminated. Strategies for accurately quantifying nucleic acids using these approaches are discussed here.

Perception, 1989

Image regions corresponding to partially hidden objects are enclosed by two types of bounding con... more Image regions corresponding to partially hidden objects are enclosed by two types of bounding contour: those inherent to the object itself (intrinsic) and those defined by occlusion (extrinsic). Intrinsic contours provide useful information regarding object shape, whereas extrinsic contours vary arbitrarily depending on accidental spatial relationships in scenes. Because extrinsic contours can only degrade the process of surface description and object recognition, it is argued that they must be removed prior to a stage of template matching. This implies that the two types of contour must be distinguished relatively early in visual processing and we hypothesize that the encoding of depth is critical for this task. The common border is attached to and regarded as intrinsic to the closer region, and detached from and regarded as extrinsic to the farther region. We also suggest that intrinsic borders aid in the segmentation of image regions and thus prevent grouping, whereas extrinsic b...

Molecular Immunology, 2008

Molecular medicine (Cambridge, Mass.)

Chronic lymphocytic leukemia (CLL) represents the outgrowth of a CD5(+) B cell. Its etiology is u... more Chronic lymphocytic leukemia (CLL) represents the outgrowth of a CD5(+) B cell. Its etiology is unknown. The structure of membrane Ig on CLL cells of unrelated patients can be remarkably similar. Therefore, antigen binding and stimulation could contribute to clonal selection and expansion as well as disease promotion. Initial studies suggest that CLL mAbs bind autoantigens. Since apoptosis can make autoantigens accessible for recognition by antibodies, and also create neo-epitopes by chemical modifications occurring naturally during this process, we sought to determine if CLL mAbs recognize autoantigens associated with apoptosis. In general, ~60% of CLL mAbs bound the surfaces of apoptotic cells, were polyreactive, and expressed unmutated IGHV. mAbs recognized two types of antigens: native molecules located within healthy cells, which relocated to the external cell surface during apoptosis; and/or neoantigens, generated by oxidation during the apoptotic process. Some of the latter e...

Transfusion, 2005

ABBREVIATIONS: ITP = immune thrombocytopenic purpura; MZ(s) = marginal zone(s); RA = rheumatoid a... more ABBREVIATIONS: ITP = immune thrombocytopenic purpura; MZ(s) = marginal zone(s); RA = rheumatoid arthritis; SpA = staphylococcal protein A.

The FASEB Journal, 2004

Many cardiovascular disease states end in progressive heart failure. Changes in intracellular cal... more Many cardiovascular disease states end in progressive heart failure. Changes in intracellular calcium handling, including a reduced activity of the sarcoplasmic reticulum calcium pump (SERCA), contribute to this contractile dysfunction. As the regulatory protein phospholamban can inhibit the calcium pump, we evaluated it as a potential target to improve cardiac function. In this study, we describe a recombinant antibody-based protein (PLN-Ab) that binds to the cytoplasmic domain of phospholamban. Fluorescence resonance energy transfer (FRET) studies suggest that PLN-Ab mimics the effects of phospholamban phosphorylation. PLN-Ab accelerated the decay of the calcium transient when expressed in neonatal rat and adult mouse ventricular cardiac myocytes. In addition, direct injection of adenovirus encoding PLN-Ab into the diabetic mouse heart enhanced contractility when measured in vivo by echo cardiography and in ex vivo Langendorff perfused hearts. The PLN-Ab provides a novel therapeutic approach to improving contractility through in vivo expression of an antibody inside cardiac myocytes.

Journal of Neuropathology and Experimental Neurology - J NEUROPATHOL EXP NEUROL, 1997

Science, 1996

Vaccination with naked DNA elicits cellular and humoral immune responses that have a T helper cel... more Vaccination with naked DNA elicits cellular and humoral immune responses that have a T helper cell type 1 bias. However, plasmid vectors expressing large amounts of gene product do not necessarily induce immune responses to the encoded antigens. Instead, the immunogenicity of plasmid DNA (pDNA) requires short immunostimulatory DNA sequences (ISS) that contain a CpG dinucleotide in a particular base context. Human monocytes transfected with pDNA or double-stranded oligonucleotides containing the ISS, but not those transfected with ISS-deficient pDNA or oligonucleotides, transcribed large amounts of interferon-alpha, interferon-beta, and interleukin-12. Although ISS are necessary for gene vaccination, they down-regulate gene expression and thus may interfere with gene replacement therapy by inducing proinflammatory cytokines.

Science, 1989

A recently developed cloning system based on the propagation of large DNA molecules as linear, ar... more A recently developed cloning system based on the propagation of large DNA molecules as linear, artificial chromosomes in the yeast Saccharomyces cerevisiae provides a potential method of cloning the entire human genome in segments of several hundred kilobase pairs. Most application of this system will require the ability to recover specific sequences from libraries of yeast artificial chromosome clones and to propagate these sequences in yeast without alterations. Two single-copy genes have now been cloned from a library of yeast artificial chromosome clones that was prepared from total human DNA. Multiple, independent isolates were obtained of the genes encoding factor IX and plasminogen activator inhibitor type 2. The clones, which ranged in size from 60 to 650 kilobases, were stable on prolonged propagation in yeast and appear to contain faithful replicas of human DNA.

Proceedings of the National Academy of Sciences, 2000

This paper was submitted directly (Track II) to the PNAS office.

Proceedings of the National Academy of Sciences, 2009

Using the Unc93b1 3d mutation that selectively abolishes nucleic acid-binding Toll-like receptor ... more Using the Unc93b1 3d mutation that selectively abolishes nucleic acid-binding Toll-like receptor (TLR) (TLR3, -7, -9) signaling, we show these endosomal TLRs are required for optimal production of IgG autoAbs, IgM rheumatoid factor, and other clinical parameters of disease in 2 lupus strains, B6-Fas lpr and BXSB. Strikingly, treatment with lipid A, an autoAb-inducing TLR4 agonist, could not overcome this requirement. The 3d mutation slightly reduced complete Freund's adjuvant (CFA)-mediated antigen presentation, but did not affect T-independent type 1 or alum-mediated T-dependent humoral responses or TLR-independent IFN production induced by cytoplasmic nucleic acids. These findings suggest that nucleic acid-sensing TLRs might act as an Achilles' heel in susceptible individuals by providing a critical pathway by which relative tolerance for nucleic acid-containing antigens is breached and systemic autoimmunity ensues. Importantly, this helps provide an explanation for the high frequency of anti-nucleic acid Abs in lupus-like systemic autoimmunity.

PLoS ONE, 2014

Autoreactive antibodies that recognize neo-determinants on apoptotic cells in mice have been prop... more Autoreactive antibodies that recognize neo-determinants on apoptotic cells in mice have been proposed to have protective, homeostatic and immunoregulatory properties, although our knowledge about the equivalent antibodies in humans has been much more limited. In the current study, human monoclonal antibodies with binding specificity for apoptotic cells were isolated from the bone marrow of healthy adults using phage display technology. These antibodies were shown to recognize phosphorylcholine (PC)-associated neo-determinants. Interestingly, three of the four identified apoptotic cell-specific antibody clones were encoded by VH3 region rearrangements with germline or nearly germline configuration without evidence of somatic hypermutation. Importantly, the different identified antibody clones had diverse heavy chain CDR3 and deduced binding surfaces as suggested by structure modeling. This may suggest a potentially great heterogeneity in human antibodies recognizing PC-related epitopes on apoptotic cells. To re-construct the postulated structural format of the parental anti-PC antibody, the dominant clone was also expressed as a recombinant human polymeric IgM, which revealed a substantially increased binding reactivity, with dose-dependent and antigen-inhibitable binding of apoptotic cells. Our findings may have implication for improved prognostic testing and therapeutic interventions in human inflammatory disease.

Nature Medicine, 2003

During the progression of atherosclerosis, autoantibodies are induced to epitopes of oxidized low... more During the progression of atherosclerosis, autoantibodies are induced to epitopes of oxidized low-density lipoprotein (oxLDL) and active immunization of hypercholesterolemic mice with oxLDL ameliorates atherogenesis. We unexpectedly found that many autoantibodies to oxLDL derived from 'naive' atherosclerotic mice share complete genetic and structural identity with antibodies from the classic anti-phosphorylcholine B-cell clone, T15, which protect against common infectious pathogens, including pneumococci. To investigate whether in vivo exposure to pneumococci can affect atherogenesis, we immunized Ldlr -/mice with Streptococcus pneumoniae. This induced high circulating levels of oxLDL-specific IgM and a persistent expansion of oxLDLspecific T15 IgM-secreting B cells primarily in the spleen, which were cross-reactive with pneumococcal determinants. Pneumococcal immunization decreased the extent of atherosclerosis, and plasma from these mice had an enhanced capacity to block the binding of oxLDL to macrophages. These studies show molecular mimicry between epitopes of oxLDL and S. pneumoniae and indicate that these immune responses can have beneficial effects.

The Journal of Immunology, 2009

Natural Abs, which arise without known immune exposure, have been described that specifically rec... more Natural Abs, which arise without known immune exposure, have been described that specifically recognize cells dying from apoptosis, but their role in innate immunity remains poorly understood. Herein, we show that the immune response to neoantigenic determinants on apoptotic thymocytes is dominated by Abs to oxidation-associated Ags, phosphorylcholine (PC), a head group that becomes exposed during programmed cell death, and malondialdehyde (MDA), a reactive aldehyde degradation product of polyunsaturated lipids produced following exposure to reactive oxidation species. While natural Abs to apoptotic cells in naive adult mice were dominated by PC and MDA specificities, the amounts of these Abs were substantially boosted by treatment of mice with apoptotic cells. Moreover, the relative amounts of PC and MDA Abs was affected by V H gene inheritance. Ab interactions with apoptotic cells also mediated the recruitment of C1q, which enhanced apoptotic cell phagocytosis by immature dendritic cells. Significantly, IgM Abs to both PC and MDA were primary factors in determining the efficiency of serum-dependent apoptotic cell phagocytosis. Hence, we demonstrate a mechanism by which certain natural Abs that recognize neoantigens on apoptotic cells, in naive mice and those induced by immune exposure to apoptotic cells, can enhance the functional capabilities of immature dendritic cells for phagocytic engulfment of apoptotic cells.