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Biomedical subjects

W W Hancock

Publications and source records attributed to W W Hancock.

At least 19 recordsLinked to original sources
PubMed2003

Combination therapy with anti-ICOS and cyclosporine enhances cardiac but not islet allograft survival.

The blockade of costimulatory signals is a powerful strategy to prevent allograft rejection and facilitate transplantation tolerance. In recent years, a series of novel costimulatory molecules have been identified, including an inducible costimulatory molecule (ICOS). To date, little has been uncovered regarding the therapeutic potential of blocking ICOS signaling in the setting of transplantation. In a fully MHC-mismatched mouse model, we studied the effect of blocking ICOS signaling using a specific monoclonal antibody (anti-ICOS mAb) in combination with cyclosporine on cardiac and islet allograft survival. We demonstrated that combined treatment with anti-ICOS mAb and cyclosporine can induce long-term graft acceptance in cardiac but not islet allografts, suggesting that the type of transplanted tissue significantly influences the immunologic patterns of graft acceptance or rejection in this model.

Animals↗
PubMed2003

Glomerular infiltration by CXCR3+ ICOS+ activated T cells in chronic allograft nephropathy with transplant glomerulopathy.

The pathogeneses of chronic allograft nephropathy (CAN), a leading cause of allograft failure, and one of its complications, transplant glomerulopathy (TGP), are unknown. Immunohistologic analysis of human renal transplant biopsies showed expression of inducible costimulator (ICOS), the chemokine receptor CXCR3, and its ligands, Mig and IP-10, by intraglomerular and periglomerular leukocytes in biopsies with CAN and TGP but not CAN alone. ICOS and CXCR3 are both characteristics of activated, effector T cells, suggesting different pathogenetic mechanisms underlying TGP vs. CAN. We conclude that targeting of specific chemokine and chemokine receptor pathways and/or ICOS may have clinical application in the prevention and treatment of TGP.

Adult↗
PubMed2001

Expression of the chemokine receptor CXCR3 and its ligand IP-10 during human cardiac allograft rejection.

BACKGROUND: Chemokines play an essential role in regulating the infiltration of leukocytes into allografts in experimental models. Little is known of their expression or function after human cardiac transplantation. METHODS AND RESULTS: We analyzed 169 sequential human endomyocardial biopsies by immunocytochemistry for infiltration by CD3(+) T cells and the expression of the chemokine receptors CCR1, CCR3, CCR5, and CXCR3. In both cross-sectional and longitudinal analyses, the expression of each of the chemokine receptors correlated with the degree of CD3(+) T-cell infiltration. In particular, the expression of CXCR3 was temporally and spatially associated with CD3(+) T-cell infiltrates and correlated with the histopathological diagnosis of acute rejection (OR, 11.73 and 4.05, respectively; P<0.001). Of 7 patients followed up longitudinally for 1 year, 4 with consecutive biopsies developed intimal thickening by intravascular ultrasound. In these patients, there was a trend for persistent expression of CD3- and CXCR3-expressing infiltrates in the later part of the first posttransplant year. The chemokines eotaxin, IP-10, lymphotactin, MCP-1, Mig, RANTES, and SDF-1 were examined in an additional 35 biopsies by RT-PCR. Eotaxin, lymphotactin, MCP-1, Mig, and SDF-1 were present in both normal and rejecting biopsies. However, the CXCR3 ligand IP-10, which was rarely expressed in normal biopsies, was markedly induced in acute rejection (OR, 19.43; P=0.01). CONCLUSIONS: The presence of CXCR3(+) T cells and the CXCR3 ligand IP-10 within endomyocardial biopsies is strongly associated with acute rejection. The CXCR3-IP-10 interaction warrants consideration as a therapeutic target in the management of cardiac allograft recipients.

Adult↗
PubMed2001

Beneficial effects of targeting CCR5 in allograft recipients.

BACKGROUND: The chemokine receptor, CCR5, and its three high-affinity ligands, macrophage inflammatory protein- (MIP) 1alpha, MIP-1beta, and regulated on activation normal T cell expressed and secreted (RANTES), are expressed by infiltrating mononuclear cells during the rejection of clinical and experimental organ allografts, although the significance of these molecules in the pathogenesis of rejection has not been established. METHODS: We studied intragraft events in four allograft models. First, we studied cardiac transplants in fully MHC-mismatched mice that were deficient in CCR5 or two of its ligands, MIP-1alpha or RANTES. Second we tested the effects of a neutralizing rat anti-mCCR5 monoclonal antibody on allograft survival. Third we assessed whether a subtherapeutic course of cyclosporine would potentiate enhance survival in CCR5-deficient recipients. Finally, we tested the effect of targeting CCR5 in a class II-mismatched model. RESULTS: Whereas mice deficient in expression of MIP-1alpha or RANTES reject fully MHC-mismatched cardiac allografts normally, CCR5-/- mice, or CCR5+/+ mice treated with a neutralizing mAb to mCCR5, show enhanced allograft survival. MHC class II-disparate mismatched are permanently accepted in CCR5-/- but not CCR5+/+ recipients. Finally, the beneficial effects of targeting of CCR5 are markedly synergistic with the effects of cyclosporine, resulting in permanent engraftment without development of chronic rejection. CONCLUSIONS: We conclude that CCR5 plays a key role in the mechanisms of host T cell and macrophage recruitment and allograft rejection, such that targeting of CCR5 clinically may be of therapeutic significance.

Animals↗
PubMed2001

Critical role of Kupffer cell-derived IL-10 for host defense in septic peritonitis.

Intra-abdominal infection in patients following major visceral surgery is associated with high mortality. Using a macrophage depletion technique, we demonstrate that in murine septic peritonitis, Kupffer cells are a major source of systemic IL-10 levels. Kupffer cell-depleted mice were highly susceptible to the lethal effects of septic peritonitis and exhibited an increased bacterial load. Kupffer cell-depleted mice were protected by the administration of an IL-10-Fc fusion protein. Loss of Kupffer cell-derived IL-10 was associated with a weak increase in serum IL-12 levels, whereas TNF, IL-1alpha, and IL-18 levels were not significantly elevated, suggesting that the loss of Kupffer cell-derived IL-10 did not result in a toxic cytokine release syndrome. Instead, loss of Kupffer cell-derived IL-10 was associated with a reduced splenocyte production of IFN-gamma that is required for immune protection in murine septic peritonitis. Therefore, the results suggest that the protective function of IL-10 in septic peritonitis may not be restricted to the anti-inflammatory activities of IL-10.

Animals↗
PubMed2001

Fibrinogen stimulates macrophage chemokine secretion through toll-like receptor 4.

Extravascular fibrin deposition is an early and persistent hallmark of inflammatory responses. Fibrin is generated from plasma-derived fibrinogen, which escapes the vasculature in response to endothelial cell retraction at sites of inflammation. Our ongoing efforts to define the physiologic functions of extravasated fibrin(ogen) have led to the discovery, reported here, that fibrinogen stimulates macrophage chemokine secretion. Differential mRNA expression analysis and RNase protection assays revealed that macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, MIP-2, and monocyte chemoattractant protein-1 are fibrinogen inducible in the RAW264.7 mouse macrophage-like cell line, and ELISA confirmed that both RAW264.7 cells and primary murine thioglycolate-elicited peritoneal macrophages up-regulate the secretion of monocyte chemoattractant protein-1 >100-fold upon exposure to fibrinogen. Human U937 and THP-1 precursor-1 (THP-1) monocytic cell lines also secreted chemokines in response to fibrinogen, upon activation with IFN-gamma and differentiation with vitamin D(3), respectively. LPS contamination could not account for our observations, as fibrinogen-induced chemokine secretion was sensitive to heat denaturation and was unaffected by the pharmacologic LPS antagonist polymyxin B. Nevertheless, fibrinogen- and LPS-induced chemokine secretion both apparently required expression of functional Toll-like receptor 4, as each was diminished in macrophages derived from C3H/HeJ mice. Thus, innate responses to fibrinogen and bacterial endotoxin may converge at the evolutionarily conserved Toll-like recognition molecules. Our data suggest that extravascular fibrin(ogen) induces macrophage chemokine expression, thereby promoting immune surveillance at sites of inflammation.

Animals↗
PubMed2001

Donor-derived IP-10 initiates development of acute allograft rejection.

An allograft is often considered an immunologically inert playing field on which host leukocytes assemble and wreak havoc. However, we demonstrate that graft-specific physiologic responses to early injury initiate and promulgate destruction of vascularized grafts. Serial analysis of allografts showed that intragraft expression of the three chemokine ligands for the CXC chemo-kine receptor CXCR3 was induced in the order of interferon (IFN)-gamma-inducible protein of 10 kD (IP-10, or CXCL10), IFN-inducible T cell alpha-chemoattractant (I-TAC; CXCL11), and then monokine induced by IFN-gamma (Mig, CXCL9). Initial IP-10 production was localized to endothelial cells, and only IP-10 was induced by isografting. Anti-IP-10 monoclonal antibodies prolonged allograft survival, but surprisingly, IP-10-deficient (IP-10(-/-)) mice acutely rejected allografts. However, though allografts from IP-10(+/+) mice were rejected by day 7, hearts from IP-10(-/-) mice survived long term. Compared with IP-10(+/+) donors, use of IP-10(-/-) donors reduced intragraft expression of cytokines, chemokines and their receptors, and associated leukocyte infiltration and graft injury. Hence, tissue-specific generation of a single chemokine in response to initial ischemia/reperfusion can initiate progressive graft infiltration and amplification of multiple effector pathways, and targeting of this proximal chemokine can prevent acute rejection. These data emphasize the pivotal role of donor-derived IP-10 in initiating alloresponses, with implications for tissue engineering to decrease immunogenicity, and demonstrate that chemokine redundancy may not be operative in vivo.

Acute Disease↗
PubMed2001

Differential NF-kappaB and IkappaB gene expression during development of cardiac allograft rejection versus CD154 monoclonal antibody-induced tolerance.

BACKGROUND: The Rel/NF-kappaB transcription factor pathway, regulated by IkappaB proteins, is considered central to immune responses, although there are surprisingly few in vivo data concerning alloresponses. METHODS: We undertook analysis of NF-kappaB and IkappaB mRNA intracardiac allograft expression, and NF-kappaB nuclear translocation, during acute rejection versus CD154 monoclonal antibody (mAb)-induced tolerance induction in fully MHC-disparate mice. RESULTS: Intragraft expression of all nine NF-kappaB and IkappaB genes increased during development of rejection, and nuclear translocation of p50, p52, and p65 was detected. CD154 mAb therapy decreased mRNA levels of all nine NF-kappaB and IkappaB genes, and impaired nuclear translocation of p50, p52, and p65 NF-kappaB proteins. However, prolonged survival could not be induced by CD154 mAb in p50- or p52-deficient allograft recipients, indicating an absolute requirement for expression of these genes in CD154 mAb-induced tolerance. CONCLUSIONS: We conclude that, whereas blanket approaches to NF-kappaB suppression are unlikely to be effective strategies for tolerance induction, a better understanding of the roles of individual NF-kappaB and IkappaB genes may allow development of more precise and effective therapies.

Animals↗
PubMed2001

Importance of ICOS-B7RP-1 costimulation in acute and chronic allograft rejection.

Primary T cell activation requires B7-CD28 and CD40-CD154 costimulation, but effector T cell functions are considered to be largely independent of these costimulatory pathways. Although blockade of costimulation with cytolytic T lymphocyte-associated antigen 4-immunoglobulin (CTLA-4-Ig) or monoclonal antibody (mAb) to CD154 prolongs allograft survival, chronic rejection follows, which suggests that additional key costimulatory pathways are active in vivo. We found that both antibody to inducible costimulator (anti-ICOS) and an ICOS-Ig fusion protein suppressed intragraft T cell activation and cytokine expression and prolonged allograft survival in a manner similar to that in ICOS-/- allograft recipients. The combination of anti-ICOS therapy and cyclosporin A led to permanent engraftment. In addition, ICOS-B7RP-1 costimulation was required for the development of chronic rejection after CD40-CD154 blockade. These data demonstrate a key role for the ICOS-B7RP-1 pathway in acute and chronic rejection and highlight the benefits of targeting this pathway in combination with the use of conventional immunosuppressive agent.

Animals↗
PubMed2001

Targeted deletion of CX(3)CR1 reveals a role for fractalkine in cardiac allograft rejection.

Fractalkine (Fk) is a structurally unusual member of the chemokine family. To determine its role in vivo, we generated mice with a targeted disruption of CX(3)CR1, the receptor for Fk. CX(3)CR1(-/-) mice were phenotypically indistinguishable from wild-type mice in a pathogen-free environment. In response to antibody-induced glomerulonephritis, CX(3)CR1(-/-) and CX(3)CR1(+/+) mice had similar levels of proteinuria and injury. CX(3)CR1(-/-) and CX(3)CR1(+/+) mice also developed similar levels of disease in myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis. We performed heterotopic MHC class I/II cardiac transplants from BALB/c mice into C57BL/6 mice. In the absence of cyclosporin A (CsA), there was no difference in graft survival time between CX(3)CR1(-/-) and CX(3)CR1(+/+) recipient mice. However, in the presence of subtherapeutic levels of CsA, graft survival time was significantly increased in the CX(3)CR1(-/-) mice. Characterization of cells infiltrating the grafts revealed a selective reduction in natural killer cells in the CX(3)CR1(-/-) recipients in the absence of CsA and a reduction in macrophages, natural killer cells, and other leukocytes in the presence of CsA. We conclude that Fk plays an important role in graft rejection. The development of CX(3)CR1 antagonists may allow reductions in the doses of immunosuppressive drugs used in transplantation.

Animals↗
PubMed2000

Requirement of the chemokine receptor CXCR3 for acute allograft rejection.

Chemokines provide signals for activation and recruitment of effector cells into sites of inflammation, acting via specific G protein-coupled receptors. However, in vitro data demonstrating the presence of multiple ligands for a given chemokine receptor, and often multiple receptors for a given chemokine, have led to concerns of biologic redundancy. Here we show that acute cardiac allograft rejection is accompanied by progressive intragraft production of the chemokines interferon (IFN)-gamma-inducible protein of 10 kD (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T cell alpha chemoattractant (I-TAC), and by infiltration of activated T cells bearing the corresponding chemokine receptor, CXCR3. We used three in vivo models to demonstrate a role for CXCR3 in the development of transplant rejection. First, CXCR3-deficient (CXCR3(-/)-) mice showed profound resistance to development of acute allograft rejection. Second, CXCR3(-/)- allograft recipients treated with a brief, subtherapeutic course of cyclosporin A maintained their allografts permanently and without evidence of chronic rejection. Third, CXCR(+/+) mice treated with an anti-CXCR3 monoclonal antibody showed prolongation of allograft survival, even if begun after the onset of rejection. Taken in conjunction with our findings of CXCR3 expression in rejecting human cardiac allografts, we conclude that CXCR3 plays a key role in T cell activation, recruitment, and allograft destruction.

Acute Disease↗
PubMed2000

Activation of the heart by donor brain death accelerates acute rejection after transplantation.

BACKGROUND: Donor brain death upregulates expression of inflammatory mediators in the heart. It is hypothesized that these nonspecific changes trigger and amplify acute rejection in unmodified recipients compared with hearts from normal living donors. We examined the inflammatory and immunological consequences of gradual-onset donor brain death on cardiac allografts after transplantation. METHODS AND RESULTS: Functioning hearts were engrafted from normotensive donors after 6 hours of ventilatory support. Hearts from brain-dead rats (Fisher, F344) were rejected significantly earlier (mean+/-SD, 9. 3+/-0.6 days) by their (Lewis) recipients than hearts from living donor controls (11.6+/-0.7 days, P=0.03). The inflammatory response of such organs was accelerated, with rapid expression of cytokines, chemokines, and adhesion molecules and brisk infiltration of associated leukocyte populations. Upregulation of major histocompatibility class II antigens increased organ immunogenicity. Acute rejection evolved in hearts from brain-dead donors more intensely and at a significantly faster rate than in controls. CONCLUSIONS: Donor brain death is deleterious to transplanted hearts. The resultant upregulation of inflammatory factors provokes host immune mechanisms and accelerates the acute rejection process in unmodified hosts.

Animals↗
PubMed2000

Modulation of experimental autoimmune encephalomyelitis: effect of altered peptide ligand on chemokine and chemokine receptor expression.

Experimental autoimmune encephalomyelitis (EAE) is a T helper 1 (Th1) cell mediated demyelinating disease and the principal animal model for multiple sclerosis. Spinal cords from SJL mice primed with proteolipid protein peptide 139-151 (pPLP) expressed the chemokines RANTES, MCP-1, MIP-2, KC, MIP-1alpha, MIP-1beta, Mig, and fractalkine. We also identified IP-10 in these samples and described a sequence polymorphism in this transcript. Chemokine expression was specific for tissues of the central nervous system. MCP-1, IP-10, and MIP-2 RNA expression significantly correlated with clinical score. Chemokine receptor expression generally correlated with ligand expression. pPLP-primed mice expressed the Th1-associated markers CCR5 and CXCR3 on mononuclear cells. In addition, cells expressing CCR1, CCR2, CCR3, CCR4, CCR8, and CXCR2 were detected. Here we demonstrate that altered peptide ligand (APL)-induced protection from EAE was accompanied by modulation of chemokine and chemokine receptor expression. Spinal cord tissue sections from APL-protected mice showed greatly reduced levels of all chemokines and of CCR1, CCR5, CCR8, CXCR2 and CXCR3. The Th2-associated chemokine receptors CCR3 and CCR4 were found in protected mice, supporting the hypothesis that Th1 but not Th2 cells are down-regulated by APL treatment. This report concludes that chemokines and chemokine receptors can be useful tools to follow modulation of autoimmune disease.

Animals↗
PubMed2000

Macrophage inflammatory protein-2 and KC induce chemokine production by mouse astrocytes.

Astrocytes are specialized cells of the CNS that are implicated in the pathogenesis of multiple sclerosis and experimental allergic encephalomyelitis. In acute and relapsing-remitting experimental allergic encephalomyelitis, the neutrophil chemoattractant CXC chemokines macrophage-inflammatory protein (MIP)-2 and KC are associated with reactive astrocytes in the parenchyma. In vitro treatment of primary astrocyte cultures with nanomolar concentrations of MIP-2 or KC markedly up-regulated expression of the monocyte/T cell chemoattractants monocyte chemoattractant protein-1, inflammatory protein-10, and RANTES by a mechanism that includes stabilization of mRNA. Production of TNF-alpha and IL-6 transcripts were also noted, as was autocrine induction of MIP-2 and KC message. In addition, low levels of MIP-1alpha and MIP-1beta were induced following treatment with MIP-2 or KC. These effects are specific to astrocytes as MIP-2 treatment of microglial cells failed to elicit chemokine production. The astrocyte chemokine receptor for MIP-2 has 2.5 nM affinity for ligand. Astrocytes from CXCR2-deficient mice still respond to KC and MIP-2, indicating the presence of an alternative or novel high affinity receptor for these ligands. We propose that this KC/MIP-2 chemokine cascade may contribute to the persistence of mononuclear cell infiltration in demyelinating autoimmune diseases.

Acute Disease↗
PubMed2000

Differential effects of cyclosporine A, methylprednisolone, mycophenolate, and rapamycin on CD154 induction and requirement for NFkappaB: implications for tolerance induction.

BACKGROUND: Recent experimental data indicate that the targeting of the costimulatory molecule CD40-ligand (CD154) may well offer an opportunity for tolerance induction in transplant recipients and patients with autoimmune diseases, although the optimal therapeutic strategy for clinical application of CD154 monoclonal antibody (mAb) is unclear. METHODS: We undertook vascularized heterotopic cardiac allograft transplantation in completely MHC-mismatched mice, treated recipients with CD154 mAb plus various immunosuppressive agents, and performed flow cytometric analysis of CD154 expression by T cells activated in vitro in the presence of corresponding immunosuppressive agents. We also tested the extent to which CD154 induction was NFkappaB-dependent by using NFkappaB/p50-deficient mice as allograft recipients and as source of cells for in vitro studies of CD154 induction, and through use of proteasome inhibitors to block IkappaBalpha degradation and NFKB activation in wild-type mice. RESULTS: Concomitant use of cyclosporin A or methylprednisolone, but not rapamycin or mycophenolate, inhibited CD154 mAb-induced allograft survival. The differential effects of these agents on CD154 mAb-induced tolerance correlated with their capacity to inhibit activation-induced CD154 expression on CD4+ T cells. Full expression of CD154 expression was found to require NF-kappaB activation, and CD154 mAb was ineffective in NF-kappaB/p50 deficient allograft recipients or control mice in which NF-kappaB activation was blocked by proteasome inhibition. CONCLUSIONS: Strategies to use CD154 mAb clinically must take into account the effects of immunosuppressive agents on CD154 induction, which seems to be at least partially NF-kappaB dependent. Our data suggest that ligation of surface-expressed CD154 provides an important signal that modulates T cell activation and thereby contributes to the effects of CD154 mAb, in addition to previously recognized actions involving blockade of CD40/CD154-dependent cell activation and activation-induced cell death.

Animals↗
PubMed2000

Activation of inflammatory mediators in rat renal isografts by donor brain death.

BACKGROUND: Brain death (BD) has been thought to influence the early course of transplanted organs by triggering a series of nonspecific inflammatory events that in turn may increase the kinetics and intensity of the immunological host responses. In this study early nonspecific, cellular, and molecular changes occurring in kidney isografts from BD donors are compared with those from normal anesthetized, ventilated controls. METHODS: After induction of brain death, the animals were mechanically ventilated for 6 hr before organ removal. Only rats with stable blood pressure (mean arterial pressure >80 mmHg) were included. Serum creatinines were measured daily. Representative grafts were harvested 6 hr after brain death and between 1 hr and 5 days after engraftment for morphology, immunohistology, and reverse transcriptase-polymerase chain reaction. The presence of serum cytokines was assessed by enzyme linked immunoabsorbant assay. RESULTS: Serum creatinine levels rose slightly in recipients from BD donors. Serum interleukin-1beta levels increased within 6 hr versus controls (P<0.05). mRNA levels of interleukin-1beta and macrophage inhibitory protein-1 in the kidneys were up-regulated transiently before engraftment (6 hr after BD) and 1 hr after revascularization (P<0.05). By immunohistology, numbers of infiltrating polymorphonuclear leukocytes peaked at 24 hr in parallel with intragraft induction of P- and E-selectin, complement, and other proinflammatory chemokines and cytokines. At 5 days, the isografts from BD donors were highly infiltrated by host leukocyte populations associated with intense up-regulation of their products. In contrast, those from control donors remained relatively normal through this initial follow-up period. CONCLUSIONS: The intense nonimmune inflammation produced in isografts after donor BD may represent the initial stages of a continuum between an initial nonspecific and later immune reactivity, when placed in the context of allotransplantation.

Animals↗
PubMed2000

Leukocyte recruitment during onset of experimental allergic encephalomyelitis is CCR1 dependent.

We have shown that macrophages and microglia present within demyelinating plaques of patients with multiple sclerosis (MS) are immunoreactive for the chemokine receptor CCR1 and its ligand, macrophage inflammatory protein-1alpha. To test the importance of CCR1 to the pathogenesis of MS, we studied the progression of experimental allergic encephalomyelitis (EAE) in CCR1(+/+) vs. CCR1(-/-) mice. After immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide, nearly all CCR1(+/+) mice developed EAE (95% incidence, severity 2.5+/-0.1), whereas CCR1(-/-) mice had less severe disease (55% incidence, p<0.001; severity 1. 2+/-0.2, p<0.001). CCR1(+/+) mice showed elevated brain mRNA for the chemokines immune protein (IP)-10, RANTES and monocyte chemoattractant protein-1 prior to disease onset, whereas only IP-10 mRNA was elevated in CCR1(-/-) mice. Both groups of mice had comparable in vitro lymphocyte proliferation and cytokine production upon stimulation with MOG peptide, and similar cutaneous hypersensitivity responses to 2,4-dinitrofluorobenzene, suggesting that CCR1(-/-) mice were not systemically immunosuppressed. These data demonstrate that deletion of a chemokine receptor is at least partially protective in EAE, and suggest that targeting of CCR1 may be of therapeutic significance clinically.

Animals↗