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Wayne W Hancock

Publications and source records attributed to Wayne W Hancock.

51 records · Page 3Linked to original sources
PubMed2003

TRAF6 is a critical factor for dendritic cell maturation and development.

IL-1 receptor (IL-1R)/Toll-like receptor (TLR) family and TNF receptor (TNFR) superfamily members are critical for regulating multiple aspects of dendritic cell (DC) biology. Several signaling pathways associated with each family utilize the adapter molecule, TRAF6, but its role in DCs is unclear. By examining TRAF6-deficient mice and bone marrow (BM) chimeras reconstituted with TRAF6-deficient fetal liver cells, we show that proper DC maturation requires TRAF6. In response to either microbial components or CD40L, TRAF6-deficient DCs fail to upregulate surface expression of MHCII and B7.2, or produce inflammatory cytokines. Moreover, LPS-treated TRAF6-deficient DCs do not exhibit an enhanced capacity to stimulate naive T cells. Interestingly, a major population of splenic DCs, the CD4(+)CD8alpha(-) subset, is nearly absent in both TRAF6-deficient mice and BM chimeras. Together these results indicate that TRAF6 regulates the critical processes required for maturation, activation, and development of DCs, the primary cellular bridge between innate and adaptive immunity.

Animals↗
PubMed2003

Allograft rejection in a new allospecific CD4+ TCR transgenic mouse.

The application of TCR transgenic mice to transplantation immunology is hampered by the limited lines available. Recently, we reported CD4+ T cell receptor (TCR) transgenic mice specific for I-Abm12 expressed on B6.C.H-2bm12 mice. Here, we characterized rejection of skin and vascularized cardiac allografts in these mice, which we term ABM (for anti-bm12). In vivo proliferative experiments reveal that all CD4 T cells in ABM mice react to bm12 antigens. Surprisingly, while ABM mice have accelerated (compared to B6 recipients) rejection of bm12 skin allografts, they, like B6 recipients, fail to acutely reject bm12 cardiac allografts. This is not due to lack of immunogenicity of bm12 hearts, as these grafts are acutely rejected by primed ABM recipients, although not by primed B6 recipients. Lastly, long-term surviving bm12 grafts in ABM recipients are relatively free from chronic rejection (compared with B6 recipients), which may be due to skewing of the CD4 repertoire towards direct alloreactivity, and consequent lack of CD4 mediated indirect allorecognition as evidenced by the lack of IgG deposition in those grafts. The results indicate that a complex interplay between responder frequency, priming and repertoire dictates the occurrence, or lack thereof, of acute and chronic rejection.

Animals↗
PubMed2003

Chemokine receptor-dependent alloresponses.

Immunologists have typically viewed alloreactivity schematically as a function of antigen presentation, expansion of alloreactive T and B cells within regional lymphoid tissues, and cellular infiltration and destruction of an allograft. Actual details of the steps between immune activation and accumulation of effector cells within a graft typically have not received much attention. However, just how cells "know" to move to and migrate within a graft or not is proving to be of increasing interest, as the chemokine-dependent mechanisms underlying leukocyte recruitment to a transplant are dissected. Experimentally, chemokine receptor targeting can prolong or induce permanent allograft survival, despite preservation of alloresponses within secondary lymphoid tissues, whereas current immunosuppressive protocols have only modest effects on chemokine production and leukocyte homing. Recent knowledge of the chemokine-dependent nature of allograft rejection, acceptance, and tolerance induction are presented as a basis for understanding the rationale for preclinical trials of chemokine receptor-targeted therapies currently underway in primate recipients of solid organ allografts.

Animals↗
PubMed2003

Viral IL-10 gene transfer inhibits the expression of multiple chemokine and chemokine receptor genes induced by inflammatory or adaptive immune stimuli.

Previously we have shown that adenovirus-mediated gene transfer and expression of vIL-10 are able to prolong cardiac allograft survival, through the inhibition of the immune response to both alloantigen and adenoviral antigens. In the current study, we have defined further mechanisms of Ad.vIL-10-mediated prolongation of cardiac allograft survival. E1- and E3-deleted adenoviral vectors encoding beta-galactosidase or vIL-10 were transferred into grafts at the time of transplantation, chemokine and chemokine receptor expression were evaluated by a pathway-specific cDNA array, and the results were confirmed with real time RT-PCR on selected genes. Ischemic injury, alloantigen and adenovirus vector induced the expression of multiple pro-inflammatory chemokines in the grafts, which likely amplify allograft rejection. Most of these Th1-related chemokine genes were inhibited or down-regulated by Ad.vIL-10 administration, which may help to decrease leukocytic infiltration and improve graft survival. Among the potent Th1 type chemokines inhibited were the CXCR3 ligands CXCL9 and CXCL10, which could directly inhibit vector-mediated gene expression in myoblasts, although targeting CXCR3 or its ligands did not prolong allograft survival with vIL-10 gene transfer. Ad.vIL-10 administration also induced the expression of the Th2-associated chemokines eotaxin-2 and MIP-1 gamma, suggesting Th1 to Th2 immune deviation. These results demonstrated that the vIL-10 gene transfer inhibits chemokine expression, preventing stimulation of innate and adaptive immunity.

Animals↗
PubMed2002

Proapoptotic Bax is hyperexpressed in isolated human islets compared with antiapoptotic Bcl-2.

BACKGROUND: Apoptosis is a well-documented pathway for islet cell death. One potential mechanism is overexpression of death-promoting Bax compared with antiapoptotic Bcl-2 in islets. METHODS: We isolated islets from 10 human pancreata and measured the expression of Bax mRNA and Bcl-2 mRNA by real-time quantitative polymerase chain reaction; islet and pancreas expression of Bax, Bcl-2, activated caspase-3, and cleaved poly (ADP-ribose) polymerase were also assessed by immunohistochemistry. Islet cell apoptosis was evaluated by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometry. RESULTS: The mean (+/-SE) level of Bax mRNA was 336+/-79 copies per nanogram of total RNA, and the level of Bcl-2 mRNA was 36+/-10 (P=0.001). A positive correlation existed between islet expression of Bax mRNA and Bcl-2 mRNA (P=0.001). The islet Bax to Bcl-2 ratio was 10.8+/-1.3 and 1.71+/-0.3 for the spleens (P=0.0001). Bax mRNA (P=0.04), but not Bcl-2 mRNA, was expressed at a higher level in islets compared with spleens. Human islets contained large numbers of cells expressing Bax protein, whereas only infrequent islet cells expressed Bcl-2 protein, activated caspase-3, and poly (ADP-ribose) polymerase. The apoptotic index was 5% by TUNEL assay, and the percentage of apoptotic islet cells was 9.7+/-2.5% by flow cytometry. Sections of human pancreas before islet isolation showed islet staining for Bax but not Bcl-2. CONCLUSIONS: Our finding that isolated human islets express Bax at a higher level compared with Bcl-2 suggests a molecular mechanism for islet cell death by apoptosis. We hypothesize that reducing islet expression of Bax, or regulating its activation, will help preserve islet cell mass after islet transplantation.

Adult↗
PubMed2002

Programmed death-1 targeting can promote allograft survival.

The recently identified CD28 homolog and costimulatory molecule programmed death-1 (PD-1) and its ligands, PD-L1 and PD-L2, which are homologs of B7, constitute an inhibitory regulatory pathway of potential therapeutic use in immune-mediated diseases. We examined the expression and functions of PD-1 and its ligands in experimental cardiac allograft rejection. In initial studies, we found that most normal tissues and cardiac isografts had minimal expression of PD-1, PD-L1, or PD-L2, but intragraft induction of all three molecules occurred during development of cardiac allograft rejection. Intragraft expression of all three genes was maintained despite therapy with cyclosporin A or rapamycin, but was prevented in the early posttransplant period by costimulation blockade using CD154 or anti-inducible costimulator mAb. We prepared PD-L1.Ig and PD-L2.Ig fusion proteins and showed that each bound to activated PD-1(+) T cells and inhibited T cell functions in vitro, thereby allowing us to test the effects of PD-1 targeting on allograft survival in vivo. Neither agent alone modulated allograft rejection in wild-type recipients. However, use of PD-L1.Ig administration in CD28(-/-) recipients, or in conjunction with immunosuppression in fully MHC-disparate combinations, markedly prolonged cardiac allograft survival, in some cases causing permanent engraftment, and was accompanied by reduced intragraft expression of IFN-gamma and IFN-gamma-induced chemokines. PD-L1.Ig use also prevented development of transplant arteriosclerosis post-CD154 mAb therapy. These data show that when combined with limited immunosuppression, or in the context of submaximal TCR or costimulatory signals, targeting of PD-1 can block allograft rejection and modulate T and B cell-dependent pathologic immune responses in vivo.

Animals↗
PubMed2002

Enforced c-REL deficiency prolongs survival of islet allografts1.

BACKGROUND: The NF-kappaB/Rel family of transcription factors regulates biologic processes ranging from apoptosis to inflammation and innate immunity. Whether c-Rel, a lymphoid-predominant member of the NF-kappaB/Rel family, is essential for transplantation immunity is not known. METHODS: We explored the role of c-Rel in the anti-allograft repertory using mice with targeted disruption of the c-Rel gene (c-Rel-/-) as recipients of H-2 mismatched islet allografts. Allogeneic DBA/2 (H-2d) islets were transplanted into the renal subcapsular space of diabetic c-Rel-/- C57BL/6 (H-2b) mice or the c-Rel +/+ C57BL/6 wild-type mice. Islet graft survival, cellular traffic into the islet grafts and their phenotype, and intragraft expression of cytokines and cytotoxic attack molecules were determined at the protein (by immunohistochemistry) and mRNA (by real-time quantitative polymerase chain reaction) levels. RESULTS: We found superior islet graft survival in the c-Rel-/- recipients compared to c-Rel+/+ C57BL/6 recipients. Splenocytes from c-Rel-/- mice proliferated poorly compared to splenocytes from the c-Rel+/+ mice on stimulation with anti-CD3 mAbs or Con A. Peri-islet infiltration composed of T lymphocytes and macrophages was found in both c-Rel+/+ recipients and c-Rel-/- recipients, but intra-islet infiltration was observed only in c-Rel+/+ recipients. Immunohistologic and molecular studies showed impaired T helper-type 1 immunity and decreased intragraft expression of cytotoxic attack molecules perforin and granzyme B in c-Rel-/- recipients as compared to wild-type recipients. CONCLUSIONS: Our results demonstrate that c-Rel is essential for robust rejection of islet allografts and support the idea that strategies that impair c-Rel function may be of value for constraining alloimmunity and facilitating survival of allogafts.

Animals↗
PubMed2002

Recipient hypertension potentiates chronic functional and structural injury of rat renal allografts.

BACKGROUND: Systemic hypertension affects many allograft recipients, is an important risk factor for chronic graft dysfunction, and is linked to reduced graft survival. The condition may up-regulate the expression of inflammatory host cells and their products. These, in turn, may significantly injure vascular endothelium and other components of allografted kidneys. METHODS: Lewis rats received orthotopic F344 renal allografts, a standard model of chronic rejection. Renovascular hypertension was produced by placing a silver clip (0.25 mm) on the renal artery of the retained contralateral native kidney 4 weeks after transplantation. Sham-clipped rats served as normotensive controls. Four recipient groups (Gp) were studied: Gp 1, rats with an allograft plus a clipped native kidney; Gp 2, those with an allograft and a sham-clipped native kidney; Gp 3, isografted animals with a clipped native kidney; and Gp 4, those bearing an isograft and a sham-clipped native kidney. Systolic blood pressure and proteinuria were measured every 2 weeks for 24 weeks. Grafts were assessed serially for morphologic and immunohistologic changes. RESULTS: Systemic blood pressure rose to hypertensive levels in Gps 1 and 3 within a week of clipping but never increased in Gps 2 and 4. Proteinuria developed in hypertensive animals but remained at baseline in normotensive controls. Intimal thickening of allograft arteries progressed to luminal obliteration with extensive perivascular and interstitial fibrosis by 24 weeks. In contrast, vascular changes in isografts of hypertensive hosts were restricted to medial hypertrophy. Tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, platelet derived growth factor (PDGF), endothelin, Il-6, major histocompatibility complex (MHC) class II, and B7 were up-regulated in allografts in hypertensive hosts. Vascular deposition of immunoglobulin (IgG) was increased. These changes were markedly less pronounced in Gp 3 isografts and minimal in the kidneys of the normotensive animals of Gps 2 and 4. CONCLUSIONS: An experimental model is presented that examines the influence of recipient hypertension in the pathogenesis of chronic dysfunction and injury developing in rat renal allografts over time.

Animals↗
PubMed2002

Immunopathogenesis of accelerated allograft rejection in sensitized recipients: humoral and nonhumoral mechanisms.

INTRODUCTION: Accelerated rejection (AccR) in sensitized recipients (second-set rejection) is considered a classic humorally mediated form of allograft rejection, although additional effector mechanisms may be involved. METHODS: We developed a model of AccR in which C57BL6 mice are sensitized by BALB/c skin grafts, followed 10 days later by transplantation of BALB/c hearts. We undertook analysis of various humoral and cellular components in this model using knockout or monoclonal antibody-treated allograft recipients. RESULTS: Sensitized mice rejected cardiac allografts in 34+/-7 hr. AccR was accompanied by endothelial deposition of immunoglobulins, complement, and fibrin, but also by dense expression of multiple chemokines and a mixed polymorphonuclear and mononuclear cellular infiltrate. Whereas neutrophil or complement depletion had no significant effect on the tempo of AccR, surprisingly B cell-deficient recipients still underwent AccR (41+/-7 hr) in conjunction with T cell and macrophage recruitment. In contrast, T cell-deficient (nude) mice maintained functioning cardiac allografts for >720 hr despite prior skin engraftment. CONCLUSIONS: AccR in sensitized experimental recipients involves multiple effector pathways. Although most previous studies have emphasized the key role of humoral pathways in mediating AccR, our data indicate that T cell-dependent mechanisms can also promote AccR, alone or in conjunction with humoral responses.

Animals↗
PubMed2002

Early and late injury to renal transplants from non-heart-beating donors.

BACKGROUND: The lack of adequate numbers of kidneys for transplantation has stimulated interest in the use of organs from non-heart-beating donors (NHBDs). The short- and long-term effects of this risk factor on kidney isografts and allografts were examined with a rat model. METHODS: NHBDs were killed by ether overdose. Kidney isografts (male Lewis rats [LEW]-->LEW) were transplanted orthotopically into bilaterally nephrectomized recipients 15, 30, 45, and 90 min after asystole to determine short-term survival patterns, which were compared to those of rats bearing kidneys from living donors (LDs, 0 min). Isografts and allografts (Fisher 344 rats-->LEW) from 45-min and 105-min NHBDs and from LD controls were placed in additional recipients in which contralateral native nephrectomy was performed on day 10 to allow the injured graft to recover from its ischemic insult. Serum creatinine, proteinuria, and graft morphology were assessed serially over a 24-week follow-up period. RESULTS: Early survival and renal dysfunction of isografted rats correlated with the interval of donor cardiac arrest before transplantation. Long-term survival of recipients of kidneys from LDs and between 45-min and 105-min NHBDs was also significantly different (100% vs. 87% vs. 37% at 24 weeks, respectively, P<0.03). Proteinuria increased progressively over time, proportionate to the period of donor asystole, and was associated with increasing cellular infiltration, tubular atrophy, and glomerulosclerosis in the grafts. The development of important functional and structural changes was intensified in NHBD allografts. LD allografts showed early changes of chronic rejection. CONCLUSIONS: The results emphasize the continuum between an initial nonspecific, donor-associated renal injury and late functional and morphologic changes associated with the interval of donor cardiac arrest. These events are accelerated in NHBD allografts that experience the added insult of host alloreactivity.

Animals↗
PubMed2002

Modulation of LIGHT-HVEM costimulation prolongs cardiac allograft survival.

LIGHT (TNFSF14), a tumor necrosis factor superfamily member expressed by activated T cells, binds to herpes virus entry mediator (HVEM) which is constitutively expressed by T cells and costimulates T cell activation in a CD28-independent manner. Given interest in regulating the effector functions of T cells in vivo, we examined the role of LIGHT-HVEM costimulation in a murine cardiac allograft rejection model. Normal hearts lacked LIGHT or HVEM mRNA expression, but allografts showed strong expression of both genes from day 3 after transplant, and in situ hybridization and immunohistology-localized LIGHT and HVEM to infiltrating leukocytes. To test the importance of LIGHT expression on allograft survival, we generated LIGHT-/- mice by homologous recombination. The mean survival of fully major histocompatibility complex-mismatched vascularized cardiac allografts in LIGHT-/- mice (10 days, P < 0.05) or cyclosporine A (CsA)-treated LIGHT+/+ mice (10 days, P < 0.05) was only slightly prolonged compared with LIGHT+/+ mice (7 days). However, mean allograft survival in CsA-treated LIGHT-/- allograft recipients (30 days) was considerably enhanced (P < 0.001) compared with the 10 days of mean survival in either untreated LIGHT-/- mice or CsA-treated LIGHT+/+ controls. Molecular analyzes showed that the beneficial effects of targeting of LIGHT in CsA-treated recipients were accompanied by decreased intragraft expression of interferon (IFN)-gamma, plus IFN-gamma-induced chemokine, inducible protein-10, and its receptor, CXCR3. Treatment of LIGHT+/+ allograft recipients with HVEM-Ig plus CsA also enhanced mean allograft survival (21 days) versus wild-type controls receiving HVEM-Ig (mean of 7 days) or CsA alone (P < 0.001). Our data suggest that T cell to T cell-mediated LIGHT/HVEM-dependent costimulation is a significant component of the host response leading to cardiac allograft rejection.

Animals↗
PubMed2002

Normalization of brain death-induced injury to rat renal allografts by recombinant soluble P-selectin glycoprotein ligand.

Donor brain death has been considered a significant risk factor for both early and late organ allograft dysfunction. This central injury not only evokes an upsurge of catecholamines with resultant peripheral tissue vasoconstriction and ischemia but also promotes release of hormones and inflammatory mediators that may also affect the organs directly. One of the resultant influences of these events is the rapid upregulation of the acute-phase adhesion molecules, the selectins. These initiate leukocyte adhesion to vascular endothelium and trigger subsequent cellular and molecular changes in the compromised tissues. An established F344 --> LEW rat model of chronic rejection was used to examine (1) whether the initial inflammatory events that develop within kidney allografts from brain-dead donors could be normalized using a recombinant soluble form of P-selectin glycoprotein ligand and (2) whether amelioration of these early changes would alter the inexorable progression of chronic allograft rejection. Untreated living donor controls experienced unrelenting chronic rejection over time. This complex process was accelerated in brain-dead donor kidneys. Treatment with P-selectin glycoprotein ligand prevented the early inflammatory changes in the transplanted organs and their subsequent (200 d) functional and morphologic manifestations, particularly when the soluble ligand was administered both to the donor before organ removal and to the recipient after engraftment. This strategy of using a naturally occurring selectin ligand to prevent donor-associated chronic graft dysfunction may be of special clinical interest in cadaver donor transplantation.

Animals↗
PubMed2002

Anti-CD28 monoclonal antibody therapy prevents chronic rejection of renal allografts in rats.

The effects of a signaling anti-CD28 mAb (JJ319), which interferes with the CD28-B7 T cell costimulation pathway thought to be involved in the development of chronic rejection of organ transplants, was investigated. Functional, morphologic, and molecular changes in rat renal allografts were examined up to 24 wk after placement. Control Lewis rats, recipients of F344 kidneys, received a single dose of a nonspecific mouse mAb intravenously on the day of transplantation (group 1). Group 2 animals were given anti-CD28 mAb in similar fashion. Group 3 animals were treated with a short course of cyclosporin A (CsA), and group 4 received both anti-CD 28 mAb and CsA. The majority (>95%) of animals in groups 2, 3, and 4 survived throughout the follow-up, compared with 28% in group 1 (P < 0.001). Group 2 and 4 recipients produced negligible proteinuria, whereas group 1 controls developed progressively increasing proteinuria after 4 wk and group 3 animals developed proteinuria by 24 wk. Allografts in groups 2 and 4 were morphologically unremarkable at 24 wk. Kidneys of group 1 animals rapidly developed changes of acute rejection, and those that survived long-term showed extensive glomerulosclerosis and interstitial fibrosis. Changes of early chronic rejection were noted in group 3 grafts. By reverse transcriptase-PCR, expression of representative inflammatory factors interferon-gamma and interleukin-10 were significantly elevated at 24 wk only in the surviving group 1 animals. A single dose of a signaling anti-CD28 mAb administered at transplantation or in combination with a short course of CsA significantly prolonged recipient survival, normalized function, and preserved the morphology of renal allografts in an established model of chronic rejection. These data support an important role for T cell costimulation in the evolution of the chronic process.

Animals↗
PubMed2001

Influence of donor brain death on chronic rejection of renal transplants in rats.

The clinical observation that the results of kidney grafts from living donors (LD), regardless of relationship with the host, are consistently superior to those of cadavers suggests an effect of brain death (BD) on organ quality and function. This condition triggers a series of nonspecific inflammatory events that increase the intensity of the acute immunologic host responses after transplantation (Tx). Herein are examined the influences of this central injury on late changes in renal transplants in rats. A standardized model of BD was used. Groups included both allografts and isografts from normotensive brain dead donors and anesthetized LD. Renal function was determined every 4 wk after Tx, at which time representative grafts were examined by morphology and by reverse transcriptase-PCR. Long-term survival of brain-dead donor transplants was significantly less than LD grafts. Proteinuria was significantly elevated in recipients of grafts from BD donors versus LD controls as early as 6 wk postoperatively and increased progressively through the 52-wk follow up. These kidneys also showed consistently more intense and progressive deterioration in renal morphology. Changes in isografts from brain-dead donors were less marked and developed at a slower tempo than in allografts but were always greater than those in controls. The transcription of cytokines was significantly increased in all brain-dead donor grafts. Donor BD accelerates the progression of long-term changes associated with kidney Tx and is an important risk factor for chronic rejection. These results explain in part the clinically noted difference in long-term function between organs from cadaver and living sources.

Animals↗