Jan Czyzyk

University of Rochester, Rochester, NY, United States

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Publications (15)68.32 Total impact

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    ABSTRACT: Type 1 diabetes mellitus (T1D) is characterized by a heightened antibody (Ab) response to pancreatic islet self-antigens, which is a biomarker of progressive islet pathology. We recently identified a novel antibody to clade B serpin that reduces islet-associated T cell accumulation and is linked to the delayed onset of T1D. As natural immunity to clade B arises early in life, we hypothesized that it may influence islet development during that time. To test this possibility healthy young Balb/c male mice were injected with serpin B13 mAb or IgG control and examined for the number and cellularity of pancreatic islets by immunofluorescence and FACS. Beta cell proliferation was assessed by measuring nucleotide analog 5-EdU incorporation into the DNA and islet Reg gene expression was measured by real time PCR. Human studies involved measuring anti-serpin B13 autoantibodies by Luminex. We found that injecting anti-serpin B13 monoclonal Ab enhanced beta cell proliferation and Reg gene expression, induced the generation of approximately 80 pancreatic islets per animal, and ultimately led to increase in the beta cell mass. These findings are relevant to human T1D because our analysis of subjects just diagnosed with T1D revealed an association between baseline anti-serpin activity and slower residual beta-cell function decline in the first year after the onset of diabetes. Our findings reveal a new role for the anti-serpin immunological response in promoting adaptive changes in the endocrine pancreas and suggests that enhancement of this response could potentially help impede the progression of T1D in humans.
    Journal of Biological Chemistry 11/2015; DOI:10.1074/jbc.M115.687848 · 4.57 Impact Factor
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    ABSTRACT: Activation of β-cell EphA5 receptors by its ligand ephrinA5 from adjacent β-cells has been reported to decrease insulin secretion during hypoglycemia. Given the similarities between islet and ventromedial hypothalamus (VMH) glucose sensing, we tested the hypothesis that the EphA5/ephrinA5 system might function within the VMH during hypoglycemia to stimulate counterregulatory hormone release as well. Counterregulatory responses and glutamine/glutamate concentrations in the VMH were assessed during a hyperinsulinemic hypoglycemic glucose clamp study in chronically catheterized awake male Sprague-Dawley rats that received an acute VMH microinjection of ephrinA5-Fc, chronic VMH knockdown, or over-expression of ephrinA5 using an adenoassociated viral construct. Local stimulation of VMH EphA5 receptors by ephrinA5-Fc or ephrinA5 overexpression increased, whereas knockdown of VMH ephrinA5 reduced counterregulatory responses during hypoglycemia. Overexpression of VMH ephrinA5 transiently increased local glutamate concentrations, whereas ephrinA5 knockdown produced profound suppression of VMH interstitial fluid glutamine concentrations in the basal state and during hypoglycemia. Changes in ephrinA5/EphA5 interactions within the VMH, a key brain glucose-sensing region, act in concert with islets to restore glucose homeostasis during acute hypoglycemia, and its effect on counterregulation may be mediated by changes in glutamate/glutamine cycling.
    Diabetes 12/2012; 62(4). DOI:10.2337/db12-0982 · 8.10 Impact Factor
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    ABSTRACT: Secretion of anti-serpinB13 autontibodies in young diabetes-prone nonobese diabetic (NOD) mice is associated with reduced inflammation in the pancreatic islets and a slower progression to autoimmune diabetes. Injection of these mice with a monoclonal antibody (mAb) against serpinB13 also leads to fewer inflammatory cells in the islets and more rapid recovery from recent-onset diabetes. An exact mechanism by which anti-serpin activity is protective remains unclear. We found that serpinB13 is expressed in the exocrine component of the mouse pancreas, including the ductal cells. We also found that anti-serpinB13 mAb blocks the inhibitory activity of serpinB13, thereby allowing partial preservation of the function of its target protease. Consistent with the hypothesis that anti-clade B serpin activity blocks the serpin from binding, exposure to exogenous anti-serpinB13 mAb or endogenous anti-serpinB13 autoantibodies resulted in the cleavage of surface molecules CD4 and CD19 in lymphocytes that accumulate in the pancreatic islets and pancreatic lymph nodes but not in the inguinal lymph nodes. This cleavage was inhibited by an E64 protease inhibitor. Consequently, T cells with the truncated form of CD4 secreted reduced levels of interferon-γ. We conclude that anti-serpin antibodies prevent serpinB13 from neutralizing proteases, thereby impairing leukocyte function and reducing the severity of autoimmune inflammation.
    Journal of Biological Chemistry 11/2012; 288(16). DOI:10.1074/jbc.M112.409664 · 4.57 Impact Factor
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    ABSTRACT: Intracellular (clade B) OVA-serpin protease inhibitors play an important role in tissue homeostasis by protecting cells from death in response to hypo-osmotic stress, heat shock, and other stimuli. It is not known whether these serpins influence immunological tolerance and the risk for autoimmune diseases. We found that a fraction of young autoimmune diabetes-prone NOD mice had elevated levels of autoantibodies against a member of clade B family known as serpinB13. High levels of anti-serpinB13 Abs were accompanied by low levels of anti-insulin autoantibodies, reduced numbers of islet-associated T cells, and delayed onset of diabetes. Exposure to anti-serpinB13 mAb alone also decreased islet inflammation, and coadministration of this reagent and a suboptimal dose of anti-CD3 mAb accelerated recovery from diabetes. In a fashion similar to that discovered in the NOD model, a deficiency in humoral activity against serpinB13 was associated with early onset of human type 1 diabetes. These findings suggest that, in addition to limiting exposure to proteases within the cell, clade B serpins help to maintain homeostasis by inducing protective humoral immunity.
    The Journal of Immunology 05/2012; 188(12):6319-27. DOI:10.4049/jimmunol.1200467 · 4.92 Impact Factor
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    ABSTRACT: The propensity of T cells to generate coordinated cytokine responses is critical for the host to develop resistance to pathogens while maintaining the state of immunotolerance to self-antigens. The exact mechanisms responsible for preventing the overproduction of proinflammatory cytokines including interferon (IFN)-gamma are not fully understood, however. In this study, we examined the role of a recently described Ras GTPase effector and repressor of the Raf/MEK/ERK cascade called impedes mitogenic signal propagation (Imp) in limiting the induction of T-cell cytokines. We found that stimulation of the T cell receptor complex leads to the rapid development of a physical association between Ras and Imp. Consistent with the hypothesis that Imp inhibits signal transduction, we also found that disengagement of this molecule by the Ras(V12G37) effector loop mutant or RNA interference markedly enhances the activation of the NFAT transcription factor and IFN-gamma secretion. A strong output of IFN-gamma is responsible for the distinct lymphocyte traffic pattern observed in vivo because the transgenic or retroviral expression of Ras(V12G37) caused T cells to accumulate preferentially in the lymph nodes and delayed their escape from the lymphoid tissue, respectively. Together, our results describe a hitherto unrecognized negative regulatory role for Imp in the production of IFN-gamma in T cells and point to Ras-Imp binding as an attractive target for therapeutic interventions in conditions involving the production of this inflammatory cytokine.
    Journal of Biological Chemistry 07/2008; 283(34):23004-15. DOI:10.1074/jbc.M804084200 · 4.57 Impact Factor
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    ABSTRACT: We here describe a novel CD4 T cell adoptive transfer model of severe experimental autoimmune encephalomyelitis in (C57BL6xB10.PL)F1 mice. This FI cross developed severe disease characterized by extensive parenchymal spinal cord and brain periventricular white matter infiltrates. In contrast, B10.PL mice developed mild disease characterized by meningeal predominant infiltrates. As determined by cDNA microarray and quantitative real time PCR expression analysis, histologic and flow cytometry analysis of inflammatory infiltrates, and attenuation of disease in class I-deficient and CD8-depleted F1 mice; this severe disease phenotype appears to be regulated by CNS infiltration of CD8 T lymphocytes early in the disease course.
    Journal of Neuroimmunology 08/2007; 187(1-2):31-43. DOI:10.1016/j.jneuroim.2007.04.007 · 2.47 Impact Factor
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    Jan Czyzyk ·
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    ABSTRACT: Toll-like receptors (TLRs) are an essential component of innate immunity, the first line of defense against invading pathogens. However, in addition to activating antimicrobial effector responses directly, TLRs lead to the induction of signals that control the activation of adaptive responses including autoimmune responses and allorecognition. This ability of TLR to control both innate and adaptive immunity has a broad applicability to the development of novel immunotherapies and antimicrobial strategies. This review discusses the basic biology of TLR and their contribution to renal disease.
    Seminars in Nephrology 04/2006; 26(2):167-72. DOI:10.1016/j.semnephrol.2005.09.007 · 3.48 Impact Factor
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    ABSTRACT: Small GTPase Ras is capable of mediating activation in T lymphocytes by using Raf kinase-dependent signaling pathway. Other effectors of Ras exist, however, suggesting that targets of Ras alternative to Raf may also contribute to T cell functions. Here we demonstrate that Ras(V12G37) mutant that fails to bind Raf, potently increases intracellular calcium concentration and cytokine production in primary antigen-stimulated T cells. From three known effectors which retain the ability to interact with Ras(V12G37), overexpression of phospholipase C epsilon but not that of RIN1 or Ral guanine nucleotide exchange factors enhanced cytokine and nuclear factor-activated T cell reporter T cell responses. Hence T cell activation can be critically regulated by the Ras effector pathway independent from Raf that can be mimicked by phospholipase C epsilon.
    Proceedings of the National Academy of Sciences 06/2003; 100(10):6003-8. DOI:10.1073/pnas.1031494100 · 9.67 Impact Factor
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    Jan Czyzyk · David Leitenberg · Tom Taylor · Kim Bottomly ·
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    ABSTRACT: By using ligands with various affinities for the T-cell receptor (TCR) and by altering the contribution of the CD45 tyrosine phosphatase, the effects of the potency of TCR-induced signals on the function of small GTPases Ras and Rap1 were studied. T cells expressing low-molecular-weight CD45 isoforms (e.g., CD45RO) exhibited the strongest activation of the Ras-dependent Elk-1 transcription factor and the highest sensitivity to the inhibitory action of dominant negative mutant Ras compared to T cells expressing high-molecular-weight CD45 isoforms (ABC). Moreover, stimulation of CD45RO(+), but not CD45ABC(+), T cells with a high-affinity TCR ligand induced suboptimal Elk-1 activation compared with the stimulation induced by an intermediate-affinity TCR-ligand interaction. This observation suggested that the Ras-dependent signaling pathway is safeguarded in CD45RO(+) expressors by a negative regulatory mechanism(s) which prohibits maximal activation of the Ras-dependent signaling events following high-avidity TCR-ligand engagement. Interestingly, the biochemical activity of another small GTPase, the Ras-like protein Rap1, which has been implicated in the functional suppression of Ras signaling, was inversely correlated with the extent of Elk-1 activation induced by different-affinity TCR ligands. Consistently, overexpression of putative Rap dominant negative mutant RapN17 or the physiologic inhibitor of Rap1, the Rap GTPase-activating protein RapGAP, augmented the Elk-1 response in CD45RO(+) T cells. This is in contrast to the suppressive effect of RapN17 and RapGAP on CD45ABC(+) T cells, underscoring the possibility that Rap1 can act as either a repressor or a potentiator of Ras effector signals, depending on CD45 isoform expression. These observations suggest that cells expressing distinct isoforms of CD45 employ different signal transduction schemes to optimize Ras-mediated signal transduction in activated T lymphocytes.
    Molecular and Cellular Biology 01/2001; 20(23):8740-7. DOI:10.1128/MCB.20.23.8740-8747.2000 · 4.78 Impact Factor
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    ABSTRACT: Protein kinase C (PKC)-dependent activation of the Ras signal transduction cascade is essential for induction of the IL-2 promoter during stimulation of T lymphocytes via the T cell receptor (TCR). In this study, the effects of PKC-activating phorbol myristate acetate (PMA) on Ras-dependent activation of transcription from the ets/AP-1 Ras-responsive promoter element were examined in human T cells. Pretreatment of Jurkat cells with the Src-family PTK inhibitor herbimycin A resulted in a 50% inhibition of transactivation of the reporter following incubation with PMA. Evidence was also obtained to suggest the participation of the leukocyte-specific protein tyrosine phosphatase CD45, a regulator of Src-like PTKs, in the PMA-induced activation of the Ras/Raf pathway. First, PMA-induced transactivation of ets/AP-1 is diminished 75% in CD45-negative variants, compared with CD45-positive cells. Second, engagement of CD45 by monoclonal antibodies suppresses the PMA response from the reporter construct. Taken together, these data suggest that Src-related proteins mediate PKC-dependent activation of the Ras/Raf pathway and implicate CD45 in the TCR-independent activation of T lymphocytes induced by agents such as PMA.
    Biochemical and Biophysical Research Communications 03/1998; 243(2):444-50. DOI:10.1006/bbrc.1998.8114 · 2.30 Impact Factor
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    J B Winfield · P D Fernsten · J K Czyzyk ·

    Transactions of the American Clinical and Climatological Association 02/1997; 108:127-35.
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    ABSTRACT: To determine the specificity of anti-CD45 autoantibodies in systemic lupus erythematosus (SLE) for native CD45 and for CD45 expressed by T cells and B cells, and at different stages of cellular activation. CD45 purified from different types of lymphocytes was examined by immunoblotting with sera from patients with SLE. Indirect immunofluorescence experiments were performed with purified anti-CD45 autoantibodies. IgM anti-CD45 autoantibodies in SLE recognize native CD45 expressed on the surface membrane of viable lymphocytes and CD45 purified from activated peripheral T cells and certain T cell lines, but not CD45 purified from B cells or resting peripheral T cells. The presence or absence of reactivity is independent of the individual isoforms expressed. Recognition of CD45 by IgM antilymphocyte autoantibodies in SLE varies with the lineage and state of activation of the lymphocyte target. This pattern of reactivity is consistent with autoantibody specificities involving CD45 glycoforms, rather than CD45 isoforms.
    Arthritis & Rheumatology 04/1996; 39(4):592-9. DOI:10.1002/art.1780390408 · 7.76 Impact Factor
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    ABSTRACT: The multivalency of cold-reactive IgM anti-lymphocyte autoantibodies, together with the local density of reactive antigens on the cell surface, may confer a capacity for a variety of immunoregulatory and non-specific physiological roles in the immune system and in SLE and other autoimmune diseases. Targets of interest in this regard include CD45, 2 microglobulin, and surface immunoglobulin. IgG anti-lymphocyte autoantibodies, while more difficult to study, also exhibit interesting specificities. However, whether any of the mechanisms by which anti-lymphocyte autoantibodies could alter cellular function actually obtain in vivo remains speculative. Essentially all of the data in this regard derive from experiments in which anti-lymphocyte autoantibody-containing SLE serum or plasma, or purified Ig fractions thereof, is combined with peripheral blood mononuclear cells in short-term culture in vitro. Thus, it is possible that anti-lymphocyte autoantibodies in SLE, rather than contributing to pathogenesis, reflect a physiological attempt by the immune system to restore homeostasis in the face of aggressive autoimmune stimulation.
    Springer Seminars in Immunopathology 11/1994; 16(2):201-210. DOI:10.1007/BF00197517 · 4.55 Impact Factor
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    ABSTRACT: Patients with SLE develop IgM autoantibodies to different isoforms of CD45, the major surface membrane protein tyrosine phosphatase on lymphocytes and other nucleated hemopoietic cells. Because such autoantibodies could have a potential role in the development of immune dysfunction in this disorder, we performed a series of experiments to characterize their antigenic specificity further. Blots of recombinant E. coli fusion proteins encoded by exons 3-7 of the p220 and p180 isoforms were uniformly non-reactive with SLE IgM, suggesting that anti-CD45 autoantibodies in SLE are directed against conformational and/or carbohydrate epitopes, rather than linear polypeptide epitopes. This issue was examined further using chemically and enzymatically modified CD45 purified from T cells by lectin affinity chromatography as substrates. Treatment of CD45 with 25 mM sodium-m-periodate, sufficient to abrogate binding to various lectins, abolished the reactivity with SLE anti-CD45 autoantibodies. On the other hand, digestion of CD45 with neuraminidase enhanced the binding of anti-CD45 autoantibodies from some of the SLE sera. This result probably reflects decreased steric hindrance or charge repulsion because the binding of mouse monoclonal antibodies directed against linear polypeptide epitopes of CD45 was similarly enhanced. Digestion of CD45 with N-glycosidase F had no effect on autoantibody staining. Taken together, these data suggest that IgM anti-CD45 autoantibodies in SLE recognize non-sialylated carbohydrate determinants in the highly O-glycosylated polymorphic domains of CD45.
    Molecular Biology Reports 02/1994; 20(2):85-95. DOI:10.1007/BF00996357 · 2.02 Impact Factor
  • J B Winfield · P Fernsten · J Czyzyk · E Wang · J Marchalonis ·

    Springer Seminars in Immunopathology 02/1994; 16(2-3):201-10. · 4.55 Impact Factor

Publication Stats

105 Citations
68.32 Total Impact Points


  • 2012
    • University of Rochester
      • Department of Pathology and Laboratory Medicine
      Rochester, NY, United States
  • 2001-2008
    • Yale University
      • Department of Immunobiology
      New Haven, Connecticut, United States
  • 2007
    • Yale-New Haven Hospital
      • Department of Pathology
      New Haven, Connecticut, United States
  • 1996-1998
    • University of North Carolina at Chapel Hill
      • • Division of Rheumatology, Allergy and Immunology
      • • Department of Medicine
      • • Thurston Arthritis Research Center
      North Carolina, United States