Kishore Narayanan

Early posttransplant inflammation promotes the development of alloimmunity and chronic human lung allograft rejection

Background. Chronic human lung allograft rejection, represented by bronchiolitis obliterans syndrome (BOS), is the single most important factor that limits the long-term survival following lung transplantation (LT). However, the pathogenesis of BOS remains unclear. We hypothesized that the early posttransplant inflammation would promote the development of donor anti–human leukocyte antigen (HLA) alloimmunity and predispose to BOS. Methods. Serum levels of interleukin (IL)-1&bgr;, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17, Eotaxin, IP-10, MIG, MCP-1, MIP-1&agr;, MIP-1&bgr;, RANTES, tumor necrosis factor (TNF)-&agr;, interferon (IFN)-&agr;, IFN-&ggr;, granulocyte-macrophage colony-stimulating factor, IL-1R&agr;, and IL-2R were serially analyzed in 31 BOS+ and matched 31 BOS− patients using quantitative multiplex bead immunoassays. Donor-specific HLA class II cellular immunity was analyzed using enzyme-linked immunospot (ELISPOT) by testing recipient peripheral blood mononuclear cells against mismatched donor HLA-DR peptides. Anti-HLA class II antibodies were monitored using flow panel reactive antibodies. Results. There was early posttransplant elevation in basal serum levels of proinflammatory chemokines IP-10 and MCP-1 and Th1-cytokines IL-1&bgr;, IL-2, IL-12, and IL-15 in BOS+ patients, compared to BOS− and normal subjects. In addition, a threefold decline in IL-10 levels was found during BOS development. BOS+ patients revealed increased development of HLA class II alloantibodies and Th1-predominant donor-specific cellular immunity with high frequency of IFN-&ggr; and low IL-5 producing T-cells. Conclusion. Early posttransplant elevation of proinflammatory mediators is associated with alloimmunity and chronic human lung allograft rejection.

Pre-exposure to sub-saturating concentrations of HLA class I antibodies confers resistance to endothelial cells against antibody complement-mediated lysis by regulating Bad through the phosphatidylinositol 3-kinase/Akt pathway.

Allografts transplanted across HLA‐sensitization results in an antibody‐mediated rejection known as hyperacute rejection. Depleting anti‐graft antibodies from the recipient by plasmapheresis prior to transplantation can prevent this rejection. We developed an in vitro model using polyclonal HLA class I antibodies obtained from highly sensitized patients awaiting transplantation,and analyzed their ability to provide signals following binding to human aortic endothelial cells (EC). Using this model, we show that EC undergo caspase 3‐dependent cell death by apoptosis upon exposure to saturating concentrations of HLA class I antibodies and complement accompanied by loss of Akt activation and phosphorylation of Bad. In contrast, exposure of EC to sub‐saturating concentrations of HLA class I antibodies conferred resistance towards antibody/complement‐mediated lysis termed accommodation. Accommodated EC exhibited reduction in the expression of the adhesion molecules ICAM‐1 and VCAM‐1 and a significant increase in the expression of anti‐apoptotic genes Bcl‐xL, Bcl‐2 and heme oxygenase‐1. Further, induction of phosphatidylinositol 3‐kinase (PI3K) and Akt activities thatfacilitate the phosphorylation of Bad were also noted. In conclusion, exposure of sub‐saturating concentrations of HLA class I antibodies results in the induction of PI3K/Akt pathway that confers resistance to endothelial cells against antibody/complement‐mediated cell death.

A significant role for histocompatibility in human islet transplantation

Background. In recent years, transplantation of islets and pancreas has become a viable option for patients debilitated with type I diabetes. The success of islet transplantation has been attributed to the ability to isolate high quality islets for transplantation and capacity to maintain the recipients immunosuppressive levels within a specific target range following transplantation. The purpose of this study was to determine the role of pretransplant sensitization to human leukocyte antigen (HLA) in islet transplantation. Methods. We retrospectively analyzed seven patients that were transplanted with islets under the auspices of the Juvenile Diabetes Research Foundation and Islet Cell Resource Center/National Institutes of Health. Humoral sensitization towards donor antigens both prior to and following islet transplantation was detected by FLOW panel reactive antibodies (PRA) and donor-specific cellular sensitization was detected by performing enzyme-linked immunospot assay analysis for cytokines interferon-γ and interleukin-2. Results. Our analysis demonstrates that humoral and cellular sensitization to histocompatibility antigens prior to and after islet transplantation are associated with the failure of transplanted islets Conclusion. Patient selection based on sensitization to donor HLA may be one of the factors crucial for the success of islet transplant. Further, in some patients, rejection of islets can be associated with sensitization to mismatched donor histocompatibility antigens.

Recognition of HLA-A2-restricted mammaglobin-A-derived epitopes by CD8+ cytotoxic T lymphocytes from breast cancer patients.

A breast cancer-associated antigen, mammaglobin-A, is specifically expressed in 80% of primary breast tumors. The definition of immune responses against this highly expressed breast cancer-specific antigen should be of great value in the development of new therapeutic strategies for breast cancer. Thus, the purpose of this study was to identify HLA-A2-restricted mammaglobin-A-derived epitopes recognized by CD8+ cytotoxic T lymphocytes (CTL). We identified seven mammaglobin-A-derived candidate epitopes that bind the HLA-A2 molecule (Mam-A2.1-7) by means of a HLA class I-peptide binding computer algorithm from the Bioinformatics & Molecular Analysis Section of the National Institutes of Health. Subsequently, we determined that CD8+ CTLs from breast cancer patients reacted to the Mam-A2.1 (83–92, LIYDSSLCDL), Mam-A2.2 (2–10, KLLMVLMLA), Mam-A2.3 (4–12, LMVLMLAAL), Mam-A2.4 (66–74, FLNQTDETL), and Mam-A2.7 (32–40, TINPQVSKT) epitopes using an IFN-c ELISPOT assay. Interestingly, healthy individuals also showed high reactivity to the Mam-A2.2 epitope. Two CD8+ CTL lines generated in vitro against TAP-deficient T2 cells loaded with the candidate epitopes showed significant cytotoxic activity against the Mam-A2.1-4 epitopes. These CD8+CTL lines recognized a HLA-A2+breast cancer cell line expressing the Mam-A2.1 epitope. In addition, DNA vaccination of HLA-A2+/human CD8+ double-transgenic mice with a DNA construct encoding the Mam-A2.1 epitope and the HLA-A2 molecule induced a significant expansion of epitope-specific CD8+ CTLs that recognize the same HLA- A2+/Mam-A2.1+ breast cancer cell line. In conclusion, these results demonstrate the immunotherapeutic potential of mammaglobin-A for the treatment and prevention of breast cancer.

Induction of obliterative airway disease by anti-HLA class I antibodies.

Anti‐HLA class I Abs are associated with the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. BOS is characterized histologically by fibrosis and airway epithelial cell apoptosis. We have previously shown that anti‐HLA class I Abs induce proliferation, growth factor production and apoptosis in airway epithelial cells in vitro. Thus, this study was designed to determine whether anti‐HLA class I Abs alone could induce obliterative airway disease (OAD) in heterotopic murine tracheal allografts. Toward this, HLA‐A*0201‐transgenic tracheal allografts were transplanted into Rag1‐deficient mice treated with the W6/32 anti‐HLA class I mAb. Allografts were harvested at days +30, +45, +60 and +90. Allografts displayed epithelial metaplasia by day +45, epithelial destruction and mild cellular infiltration by day +60 and complete lumen obliteration and moderate cellular infiltration by day +90. Anti‐HLA class I Abs induced the production of several growth factors and growth factor receptors and apoptosis of parenchymal cells in the allograft. In addition, anti‐HLA class I Abs induced macrophages and granulocytes infiltration. The results from this study demonstrate that anti‐HLA class I Abs play an important role in the pathogenesis of OAD by inducing growth factor production, apoptosis and chemotaxis of inflammatory cells.

Pirfenidone inhibits obliterative airway disease in a murine heterotopic tracheal transplant model1

Background. Chronic lung allograft rejection in the form of bronchiolitis obliterans syndrome and its histopathologic correlate, obliterative bronchiolitis (OB), are a major source of morbidity and mortality after lung transplantation. Murine heterotopic tracheal transplants into fully allogeneic mismatched recipients develop obliterative airway disease (OAD), which is a suitable model of OB. Using this murine heterotopic tracheal allograft model, we evaluated the effect of pirfenidone, a novel antifibrotic agent, on the development of OAD. Methods. Mice transplanted with complete MHC-mismatched tracheal allografts received pirfenidone (0.5%) in pulverized food according to different schedules: daily for the first 14 days after transplantation or daily for the duration of the study beginning on posttransplantation days 0, 5, or 10. Results. Mice on a continuous daily regimen of pirfenidone failed to develop evidence of chronic allograft rejection at the termination of the study (60 days). Mice receiving pirfenidone limited to the early posttransplantation period had delayed onset of OAD to 60 days. Forty percent (2/5) of mice receiving a continuous regimen of pirfenidone beginning on day 5 after transplantation had no evidence of OAD at 28 days. However, when the drug was started on day 10, all mice developed OAD by 28 days. Conclusions. Our results demonstrate a delay of onset or abrogation of OAD when pirfenidone is administered in the early posttransplantation period. These findings suggest that pirfenidone is a candidate drug to be evaluated for prevention of the fibrotic changes seen in OB in human recipients of lung transplants.

Characterization of virus-specific T-cell immunity in liver allograft recipients with HCV-induced cirrhosis.

Recurrent hepatitis C infection (HCV) following liver transplantation causes accelerated allograft cirrhosis. Here we characterized HCV‐specific immunity in adult liver transplant recipients (n = 74) with and without allograft cirrhosis. Patients were divided into hepatic inflammation/no cirrhosis (METAVIR scores 0–2, HIN) and hepatic cirrhosis (score 3–4, HFC). As control, 20 normal subjects and 10 non‐HCV liver transplant patients were included. Twenty‐five different serum cytokines were analyzed using LUMINEX. Frequency of T‐cells specific to HCV‐derived proteins (NS3, NS4, NS5, Core) was characterized using ELISPOT immunoassays. There was no difference in clinical characteristics between HIN (n = 49) and HFC (n = 25) groups. HIN group had high serum IFN‐γ and IL‐12 while HFC demonstrated elevated IL‐4, IL‐5 and IL‐10 (p < 0.01). HCV (NS3, NS4, NS5, Core)‐specific IFN‐γ‐producing CD4+ T‐cells were elevated in the HIN group whereas the HFC patients showed predominance of HCV‐specific IL‐5 and IL‐10‐producing CD4+ T‐cells. Conclusions: Lack of HCV‐specific Th1‐type T‐cell immunity is observed in liver transplant recipients with advanced allograft cirrhosis.

Mechanism of accommodation in a sensitized human leukocyte antigen transgenic murine cardiac transplant model

Background. Presence of donor-specific antibodies (Abs) is detrimental to posttransplant allograft function. Some sensitized recipients have successfully undergone transplantation after pretransplant conditioning regimen using plasmapheresis and/or intravenous immunoglobulin therapy, but underlying mechanisms that confer such allograft protection are undefined. Methods. We developed a single human leukocyte antigen (HLA)-mismatched heterotopic murine heart transplant model (HLA-A2 into HLA-A2-sensitized-C57BL/6) to determine whether pretreatment of donors with low concentration of HLA class I (W6/32) or control Ab (C1.18.4) will confer protection. Expression levels of survival genes, Bcl-2 and heme oxygenase-1, were analyzed by gene array analysis and quantitative real-time polymerase chain reaction. Expression levels of cytokine panel were analyzed by Luminex. Role of Bcl-2 in the induction of allograft protection was analyzed by silencing the Bcl-2 expression in the donor hearts using a small hairpin (shRNA) specific for Bcl-2. Results. Control Ab-pretreated hearts were rejected in less than 5 days demonstrating hemorrhage, Ab, and C4 deposition. In contrast, W6/32-pretreated hearts were rejected at 15 days (P<0.05) that was prolonged to 25 days with antilymphocyte serum treatment. W6/32-pretreated hearts on day 5 exhibited increased expression of Bcl-2 (5.5-folds), Bcl-xl (5.5-folds), and heme oxygenase-1 (4.4-folds); decreased expression of ICAM-1, VCAM-1 (3.2-fold), along with reduced levels of cytokines interleukin (IL)-1&bgr; (4.4-folds), tumor necrosis factor &agr; (3.7-folds), IL-6 (7.5-folds), IL-12 (2.3-folds) and chemokines monocyte chemotactic protein 1 (4.5-folds), MIG (4.4-folds), MIP-1&agr; (3.4-folds), and IL-8 (3.1-folds). Silencing of Bcl-2 in accommodated hearts before transplant resulted in loss of protection with rejection (9±3 vs. 15±2days, P<0.05). Conclusion. Pretreatment of hearts with low levels of anti-HLA Abs increases expression of antiapoptotic genes that inhibits caspases, leading to decreased inflammatory cytokines and chemokines, which promote allograft survival.

Elevated soluble CD30 characterizes patients with hepatitis C virus-induced liver allograft cirrhosis.

Hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) significantly accelerates progression to allograft cirrhosis. Current biochemical parameters to monitor progression of chronic HCV after OLT have yielded low specificity and sensitivity. Here we investigated the HCV-specific immunity and serum levels of soluble CD30 (sCD30), a novel marker of Th2 immunity, in patients with and without allograft cirrhosis. Patients with hepatic inflammation but no cirrhosis (HIN, n=20) revealed elevated serum interferon (IFN)-gamma and high frequency of IFN-gamma producing CD4 T(h1) cells compared to those with hepatic cirrhosis (HFC, n=20) that had high interleukin (IL)-5 and IL-5 producing CD4 T(h2) cells. Patients with HFC, but not HIN, were found to have significantly higher levels of sCD30. Therefore, we conclude that lack of optimal Th1-type CD4 T cells is associated with HCV-induced allograft cirrhosis. Further, sCD30 may represent a novel marker for surveillance of hepatic cirrhosis in transplant recipients with chronic HCV infection.