P57 Hydrogen sulfide treatment reduces activation of ischemia–reperfusion injury-induced tissue inflammatory processes and resultant recipient adaptive immune response to donor tissue during allogeneic renal transplantation

Abstract

Background Organ procurement is inherently associated with ischemia–reperfusion injury (IRI), resulting from loss and subsequent restoration of blood flow and is detrimental to short- and long-term graft function and survival. Treatment of donor organs with endogenously produced gasotransmitters such as hydrogen sulfide (H 2 S) is a novel method of mitigating IRI during transplantation, as previously shown in a model of murine syngeneic renal transplantation (RTx) [1] . The protective effects of H 2 S against IRI during allogeneic RTx, in which genetically dissimilar grafts are targeted by the recipient immune system causing organ rejection, have not yet been studied. Since H 2 S is known to exhibit anti-inflammatory actions during tissue IRI, we postulated that H 2 S treatment during allogeneic RTx could reduce graft inflammation and modulate the resultant recipient immune response against donor tissue. Methods Following bilateral native nephrectomy, recipient Lewis rats underwent RTx with left kidneys obtained from Brown Norway donor rats that were flushed, at the time of procurement, with either cold (4°C) University of Wisconsin standard preservation solution (UW group) or cold UW + H 2 S donor molecule (150 μ M NaHS) (H 2 S group) and stored for 6 h at 4°C in the same solution. Sham animals were also followed. Renal grafts were obtained at post-operative day 2 and RNA was isolated from renal homogenates for gene microarray analysis (Affymetrix Rat Gene 1.0 ST Microarray). Additionally, serum was collected post-operatively at day 1 to 2 and at time of sacrifice to determine the relative abundance of allo-reactive serum antibodies. TIB-120 cells (ATCC), a rat B-cell line heterozygous for Brown Norway and Lewis alleles, were incubated with serum from transplant recipients in each treatment group, stained for bound rat IgG/M antibodies and analyzed via flow cytometry. Results Upon microarray analysis both treatment groups exhibited significant enrichment in genes involved in inflammatory and innate immune responses as well as cytokine signaling and antigen processing at day 2 compared to Sham (p 2 S treated grafts had markedly reduced enrichment scores in each of these pro-inflammatory processes compared to UW. Upon allo-antibody binding analysis both UW and H 2 S treatment groups exhibited similar trends, with more cells unbound by allo-antibodies at day 1 to 2 and few unbound cells at time of sacrifice. However, while cells incubated with UW serum at day 1 to 2 exhibited markedly more allo-antibody binding (27% unbound cells) compared to cells incubated with naive Sham serum (37% unbound cells), cells incubated with H 2 S serum at day 1 to 2 exhibited similar levels of allo-antibody binding (40% cells unbound) as those incubated with Sham serum. These findings indicate that H 2 S treated animals experienced less acute graft inflammation, leading to a delayed induction of adaptive immune response to donor tissue compared to UW alone. Conclusions These findings are the first to report that H 2 S treatment may modulate the recipient immune response to donor tissue during allogeneic RTx. This phenomenon could represent an important underlying mechanism of H 2 S-mediated protection against renal injury early in the transplant curriculum, ultimately prolonging the survival and function renal allografts.