Histopathological Changes of Long-Term Peritoneal Dialysis Using Physiological Solutions: A Case Report and Review of the Literature.

BACKGROUND: Long-term peritoneal dialysis (PD), especially with nonphysiological solutions, is afflicted with the severe complication of encapsulating peritoneal sclerosis (EPS). Physiologic PD solutions have been introduced to reduce pH trauma. Data on peritoneal biopsies in pediatrics with long-term PD using physiological solutions are scant. CASE REPORT: We report an adolescent who had been on 10-h continuous hourly cycles using mostly 2.27% Physioneal™ for 5 years. There were two episodes of peritonitis in October 2017 (Klebsiella oxytoca) and May 2018 (Klebsiella pneumoniae), which were treated promptly. This adolescent, who lost two kidney transplants from recurrent focal and segmental glomerulosclerosis, underwent a peritoneal membrane biopsy at the time of a third PD catheter placement, 16 months after the second renal transplant. Laparoscopically, the peritoneum appeared grossly normal, but fibrosis and abundant hemosiderin deposition were noted on histology. The thickness of the peritoneum was 200-900 (mean 680) µm; normal for age of 14 years is 297 [IQR 229, 384] µm. The peritoneum biopsy did not show specific EPS findings, as the mesothelial cells were intact, and there was a lack of fibrin exudation, neo-membrane, fibroblast proliferation, infiltration, or calcification. CONCLUSIONS: While the biopsy was reassuring with respect to the absence of EPS, significant histopathological changes suggest that avoiding pH trauma may not ameliorate the effects of glucose exposure in long-term PD.

When donor T cells attack: The curious case of liver transplant-associated acute graft-versus-host-disease.

Graft versus host disease is a rare but deadly complication of solid organ transplant. Clinical features of graft-versus-host-disease are non-specific, which may lead to delayed diagnosis as more common conditions including infections or drug reactions are considered. We describe a 54-year-old male patient who underwent liver transplantation for alcohol use disorder-related cirrhosis and developed acute graft-versus-host disease. Initial clinical presentation included dermatitis, bone marrow failure and enteritis. Results of skin biopsy and cytogenetic studies were consistent with liver transplant-associated acute graft-versus-host disease. The importance of this case is to highlight to transplant physicians and surgeons the challenges of diagnosing graft-versus-host-disease. In our case, pre-existing partnerships among the liver and hematopoietic stem cell transplant teams, transfusion medicine specialists, critical care specialists and facilitated timely communication relevant to confirming graft-versus-host disease. We propose an algorithm to assist in the workup of suspected graft-versus-host disease. Because this condition is characterized by high mortality, a high index of suspicion is imperative for prompt diagnosis and optimal management of the donor-recipient immune interaction when patients present with classic clinical features.

Supplemental hydrogen sulfide in models of renal transplantation after cardiac death.

BACKGROUND: The increasing use of kidneys from donations after cardiac death (DCD) for renal transplantation is hindered by negative outcomes owing to organ injury after prolonged warm and cold ischemia-reperfusion. Recently, hydrogen sulfide (H2S) has shown cytoprotective effects against ischemia-reperfusion injury; however, its effectiveness in the context of DCD renal transplantation is unknown. METHODS: We tested a novel 30-day in vivo syngeneic murine model of DCD renal transplantation, in which the donor kidney was clamped for 30 minutes and stored for 18 hours in cold University of Wisconsin (UW) solution or UW with 150 µM sodium hydrogen sulfide (UW + NaHS) before transplantation. We also tested a 7-day in vivo porcine model of DCD renal autotransplantation, in which the left kidney was clamped for 60 minutes and preserved for 24 hours using hypothermic perfusion with UW or UW + 150 µM NaHS before autotransplantation. We collected blood and urine samples periodically, and collected kidney samples at the end point for histopathology and quantitative reverse transcription polymerase chain reaction. RESULTS: Rats that received H2S-treated kidneys showed significantly higher survival, faster recovery of graft function and significantly lower acute tubular necrosis than controls. Pig kidneys perfused with UW + NaHS showed significantly higher renal blood flow and lower renal resistance than control kidneys after 24 hours of perfusion. After autotransplantation, pigs that received H2S-treated kidneys showed significantly lower serum creatinine on days 1 and 7 after transplantation. Rat and pig kidneys treated with H2S also showed more protective gene expression profiles than controls. CONCLUSION: Our findings support the potential use of H2S-supplemented UW solution during cold storage as a novel and practical means to improve DCD graft survival and function.

Comparison of Centrifugal and Pulsatile Perfusion to Preserve Donor Kidneys Using Ex Vivo Subnormothermic Perfusion.

Objective We have previously demonstrated benefits of kidney preservation utilizing an oxygenated subnormothermic ex vivo perfusion platform. Herein, we aim to compare pulsatile versus centrifugal (steady and uniform flow) perfusion with the goal of optimizing renal preservation with these devices. Materials and methods: Pig kidneys were procured following 30 min of warm ischemia by cross-clamping both renal arteries. Paired kidneys were cannulated and underwent either: oxygenated pulsatile or centrifugal perfusion using a hemoglobin oxygen carrier at room temperature with our ex vivo machine perfusion platform for 4 hr. Kidneys were reperfused with whole blood for 4 hr at 37° C. Renal function, pathology and evidence of inflammation were assessed post-perfusion. Results: Both pump systems performed equally well with organs exhibiting similar renal blood flow, and function post-reperfusion. Histologic evidence of renal damage using apoptosis staining and acute tubular necrosis scores was similar between groups. This was corroborated with urinary assessment of renal damage (NGAL 1) and inflammation (IL-6), as levels were similar between groups. Conclusion: In our porcine model with added warm ischemia simulating the effects of reperfusion after transplantation, pulsatile perfusion yielded similar renal protection compared with centrifugal perfusion kidney preservation. Both methods of perfusion can be used in ex vivo kidney perfusion systems.

Sodium thiosulfate-supplemented UW solution protects renal grafts against prolonged cold ischemia-reperfusion injury in a murine model of syngeneic kidney transplantation.

INTRODUCTION: Cold ischemia-reperfusion injury (IRI) is an inevitable event that increases post-transplant complications. We have previously demonstrated that supplementation of University of Wisconsin (UW) solution with non-FDA-approved hydrogen sulfide (H2S) donor molecules minimizes cold IRI and improves renal graft function after transplantation. The present study investigates whether an FDA-approved H2S donor molecule, sodium thiosulfate (STS), will have the same or superior effect in a clinically relevant rat model of syngeneic orthotopic kidney transplantation. METHOD: Thirty Lewis rats underwent bilateral nephrectomy followed by syngeneic orthotopic transplantation of the left kidney after 24-hour preservation in either UW or UW+STS solution at 4 °C. Rats were monitored to post-transplant day 14 and sacrificed to assess renal function (urine output, serum creatinine and blood urea nitrogen). Kidney sections were stained with H&E, TUNEL, CD68, and myeloperoxidase (MPO) to detect acute tubular necrosis (ATN), apoptosis, macrophage infiltration, and neutrophil infiltration. RESULT: UW+STS grafts showed significantly improved graft function immediately after transplantation, with improved recipient survival compared to UW grafts (p < 0.05). Histopathological examination revealed significantly reduced ATN, apoptosis, macrophage and neutrophil infiltration and downregulation of pro-inflammatory and pro-apoptotic genes in UW+STS grafts compared to UW grafts (p < 0.05). CONCLUSION: We show for the first time that preservation of renal grafts in STS-supplemented UW solution protects against prolonged cold IRI by suppressing apoptotic and inflammatory pathways, and thereby improving graft function and prolonging recipient survival. This could represent a novel clinically applicable therapeutic strategy to minimize the detrimental clinical outcome of prolonged cold IRI in kidney transplantation.

Cyclophilin D Regulates the Nuclear Translocation of AIF, Cardiac Endothelial Cell Necroptosis and Murine Cardiac Transplant Injury.

Ischemia-reperfusion injury (IRI) is an inevitable consequence of organ transplant procedure and associated with acute and chronic organ rejection in transplantation. IRI leads to various forms of programmed cell death, which worsens tissue damage and accelerates transplant rejection. We recently demonstrated that necroptosis participates in murine cardiac microvascular endothelial cell (MVEC) death and murine cardiac transplant rejection. However, MVEC death under a more complex IRI model has not been studied. In this study, we found that simulating IRI conditions in vitro by hypoxia, reoxygenation and treatment with inflammatory cytokines induced necroptosis in MVECs. Interestingly, the apoptosis-inducing factor (AIF) translocated to the nucleus during MVEC necroptosis, which is regulated by the mitochondrial permeability molecule cyclophilin D (CypD). Furthermore, CypD deficiency in donor cardiac grafts inhibited AIF translocation and mitigated graft IRI and rejection (n = 7; p = 0.002). Our studies indicate that CypD and AIF play significant roles in MVEC necroptosis and cardiac transplant rejection following IRI. Targeting CypD and its downstream AIF may be a plausible approach to inhibit IRI-caused cardiac damage and improve transplant survival.

Pilomatrixoma with Atypical Features: A Case Report.

Pilomatrixoma is an uncommon, benign tumor with differentiation towards both the hair matrix and cells arising in the cortex, most frequently appearing in the first or second decade of life. In rare instances, pilomatrixomas can show malignant transformation. Pilomatrix carcinoma is extremely uncommon and has traditionally been considered a tumor of low malignant potential; however, a high local recurrence rate has been reported. There is a paucity of literature on these lesions, with only a few reports describing the spectrum of malignant changes seen in these lesions. In this case report, we present a case of pilomatrixoma in an adult patient showing atypical features. While the tumor is small, there are focal features that suggest progression to malignancy, but do not fulfill the criteria for pilomatrix carcinoma. These focal atypical features include a focal infiltrative pattern at the periphery, with a variable cytological atypia and an increased mitotic rate, up to five mitotic events/high-power field. Irregular foci of central necrosis (comedonecrosis) were present in several lobules. Some of the features identified were similar to a subset of pilomatrixoma, known as "proliferating pilomatrixoma." However, our case did not have the diffuse changes or larger size that has been frequently reported in "proliferating pilomatrixoma." In conclusion, given the lack of focality of the changes, the lesion in our case is best described as a pilomatricoma with atypical features. Furthermore, our case may highlight the need to ensure close clinical follow-up for these lesions with unexpected atypical features that raise concern of recurrence and malignant transformation.

Loss of Thymine DNA Glycosylase Causes Dysregulation of Bile Acid Homeostasis and Hepatocellular Carcinoma.

Thymine DNA glycosylase (TDG) is a nuclear receptor coactivator that plays an essential role in the maintenance of epigenetic stability in cells. Here, we demonstrate that the conditional deletion of TDG in adult mice results in a male-predominant onset of hepatocellular carcinoma (HCC). TDG loss leads to a prediabetic state, as well as bile acid (BA) accumulation in the liver and serum of male mice. Consistent with these data, TDG deletion led to dysregulation of the farnesoid X receptor (FXR) and small heterodimer partner (SHP) regulatory cascade in the liver. FXR and SHP are tumor suppressors of HCC and play an essential role in BA and glucose homeostasis. These results indicate that TDG functions as a tumor suppressor of HCC by regulating a transcriptional program that protects against the development of glucose intolerance and BA accumulation in the liver.

EBV-positive T/NK-associated lymphoproliferative disorders of childhood: A complete autopsy report.

INTRODUCTION: Epstein-Barr Virus (EBV)-associated systemic T-cell lymphoproliferative disorder of childhood is a rare but severe manifestation of chronic EBV infection. Despite several case reports characterizing this rare hematological neoplasm, the literature describes extensive heterogeneity in the presentation of this disease. CASE PRESENTATION: Here we present a complete autopsy of a 16-year-old girl who ultimately succumbed to EBV-associated systemic T-cell lymphoproliferative disorder of childhood. Her clinical presentation demonstrated a non-specific pharyngitis with positive mono spot test, evolving into fulminant multi-organ failure, disseminated intravascular coagulopathy, sepsis, and ultimately death. CONCLUSIONS: Post-mortem findings included extensive hemorrhage, and infiltration of the liver, spleen, lymph nodes and bone marrow with neoplastic T-cells. There was extensive hemophagocytic lymphohistiocytosis (HLH) within these organs, suggesting overlap between the EBV-associated systemic T-cell lymphoproliferative disorder of childhood and EBV-associated HLH. We hope these findings provide a more comprehensive overview of several possible manifestations of EBV-associated systemic T-cell lymphoproliferative disorder of childhood.

Loss of receptor interacting protein kinases 3 and caspase-8 augments intrinsic apoptosis in tubular epithelial cell and promote kidney ischaemia-reperfusion injury.

BACKGROUND: Ischaemia-reperfusion injury (IRI) is associated with programmed cell death that promotes inflammation and organ dysfunction. Necroptosis is mediated by members of receptor interacting protein kinases (RIPK1/3). Inhibition of RIPK1/3 provides a pro-survival benefit in kidney IRI. Caspase-8 initiates apoptosis and contributes to IRI. We studied whether inhibiting both RIPK3 and caspase-8 would provide an additional benefit in kidney IRI. METHODS: A clamp was applied to the left kidney pedicle for 45 min followed by right kidney nephrectomy. Kidney and serum from wild type, RIPK3-/- , and RIPK3-/- caspase-8-/- double knockout (DKO) mice were collected post-IRI for assessment of injury. Tubular epithelial cells (TEC) isolated from wild type, RIPK3-/- , and DKO mice were treated with interferons-γ and interleukin-1ß to induce apoptotic death. RESULTS: Kidney IRI of DKO mice did not show improvement over RIPK3-/- mice. We have found that DKO triggered 'intrinsic' apoptosis in TEC in response to interleukin-1ß and interferons-γ. Up-regulation of the B-cell lymphoma 2 (Bcl-2)-associated death promoter, the Bcl-2-homologous antagonist killer and Bcl-2-associated X protein and enhanced activation of caspase-3 and 9 were found in DKO TEC. TEC infected with Murine cytomegalovirus that encodes multiple cell death inhibitors resist to death. CONCLUSION: We show that the deletion of both RIPK3 and caspase-8 does not provide additive benefit in IRI or TEC death and may enhance injury by up-regulation of intrinsic apoptosis. This suggests blocking multiple death pathways may be required for the prevention of kidney IRI clinically.

Mitochondrial permeability regulates cardiac endothelial cell necroptosis and cardiac allograft rejection.

Transplantation is invariably associated with programmed cell death including apoptosis and necrosis, resulting in delayed graft function and organ rejection. We have demonstrated the contribution of necroptosis to mouse microvascular endothelial cell (MVEC) death and transplant rejection. Organ injury results in the opening of mitochondrial permeability transition pores (mPTPs), which can trigger apoptotic molecules release that ultimately results in cell death. The effect of mPTPs in the necroptotic pathway remains controversial; importantly, their role in transplant rejection is not clear. In this study, tumor necrosis factor-α triggered MVECs to undergo receptor-interacting protein kinase family (RIPK1/3)-dependent necroptosis. Interestingly, inhibition of mPTP opening could also inhibit necroptotic cell death. Cyclophilin-D (Cyp-D) is a key regulator of the mPTPs. Both inhibition and deficiency of Cyp-D protected MVECs from necroptosis (n = 3, P < .00001). Additionally, inhibition of Cyp-D attenuated RIPK3-downstream mixed-lineage kinase domain-like protein phosphorylation. In vivo, Cyp-D-deficient cardiac grafts showed prolonged survival in allogeneic BALB/c mice posttransplant compared with wild-type grafts (n = 7, P < .0001). Our study results suggest that the mPTPs may be important mechanistic mediators of necroptosis in cardiac grafts. There is therapeutic potential in targeting cell death via inhibition of the mPTP-regulating molecule Cyp-D to prevent cardiac graft rejection.

CORM-401 Reduces Ischemia Reperfusion Injury in an Ex Vivo Renal Porcine Model of the Donation After Circulatory Death.

BACKGROUND: Carbon monoxide (CO) inhalation protects organ by reducing inflammation and cell death during transplantation processes in animal model. However, using CO in clinical transplantation is difficult due to its delivery in a controlled manner. A manganese-containing CO releasing molecules (CORM)-401 has recently been synthesized which can efficiently deliver 3 molar equivalents of CO. We report the ability of this anti-inflammatory CORM-401 to reduce ischemia reperfusion injury associated with prolonged cold storage of renal allografts obtained from donation after circulatory death in a porcine model of transplantation. METHODS: To stimulate donation after circulatory death condition, kidneys from large male Landrace pig were retrieved after 1 hour warm ischemia in situ by cross-clamping the renal pedicle. Procured kidneys, after a brief flushing with histidine-tryptophan-ketoglutarate solution were subjected to pulsatile perfusion at 4°C with University of Wisconsin solution for 4 hours and both kidneys were treated with either 200 µM CORM-401 or inactive CORM-401, respectively. Kidneys were then reperfused with normothermic isogeneic porcine blood through oxygenated pulsatile perfusion for 10 hours. Urine was collected, vascular flow was assessed during reperfusion and histopathology was assessed after 10 hours of reperfusion. RESULTS: We have found that CORM-401 administration reduced urinary protein excretion, attenuated kidney damage markers (kidney damage marker-1 and neutrophil gelatinase-associated lipocalin), and reduced ATN and dUTP nick end labeling staining in histopathologic sections. CORM-401 also prevented intrarenal hemorrhage and vascular clotting during reperfusion. Mechanistically, CORM-401 appeared to exert anti-inflammatory actions by suppressing Toll-like receptors 2, 4, and 6. CONCLUSIONS: Carbon monoxide releasing molecules-401 provides renal protection after cold storage of kidneys and provides a novel clinically relevant ex vivo organ preservation strategy.

Daily therapy with a slow-releasing H2S donor GYY4137 enables early functional recovery and ameliorates renal injury associated with urinary obstruction.

OBJECTIVES: To assess the effects of slow-releasing H2S donor GYY4137 on post-obstructive renal function and injury following unilateral ureteral obstruction (UUO) by using the UUO and reimplantation (UUO-R) model in rats and to elucidate potential mechanisms by using an in vitro model of epithelial-mesenchymal transition (EMT). METHODS: Male Lewis rats underwent UUO at the left ureterovesical junction. From post-operative day (POD) 1-13, rats received daily intraperitoneal (IP) injection of phosphate buffered saline (PBS, 1 mL) or GYY4137 (200 µmol/kg/day in 1 mL PBS, IP). On POD 14, the ureter was reimplanted back into the bladder, followed by a right nephrectomy. Urine and serum samples were collected to monitor renal function. On POD 30, the left kidney was removed and tissue sections were stained with H&E, TUNEL, CD68, CD206, myeloperoxidase, and Masson's trichrome to determine cortical thickness, apoptosis, inflammation, and fibrosis. In our in vitro model of EMT, NRK52E cells were treated with 10 ng/mL TGF-ß1, 10 µM GYY4137 and/or 50 µM GYY4137. Western blot analysis was performed to determine the expression of E-cadherin, vimentin, Smad7 and TGF-ß1 receptor II (TßRII). RESULTS: GYY4137 led to a moderate decrease in post-obstructive serum creatinine, cystatin C and FENa. We also observed a trend towards a decrease in post-obstructive proteinuria following GYY4137 treatment. Histologically, we observed a significant decrease in apoptosis, inflammation, and fibrosis. Furthermore, our in vitro studies demonstrate that in the presence of TGF-ß1, GYY4137 significantly decreases vimentin and TßRII and significantly increases E-cadherin and Smad7. CONCLUSIONS: H2S may help to accelerate the recovery of renal function post-obstruction and attenuates renal injury associated with UUO. It is possible that H2S mitigates fibrosis by regulating the TGF-ß1-mediated EMT pathway. Taken together, our data suggest that H2S may be a potential novel therapy for improving renal function and limiting renal injury associated with obstructive uropathy.

Reliability of EUS indices to detect inflammation in ulcerative colitis.

BACKGROUND AND AIMS: EUS is a potentially useful modality to assess severity of inflammation in ulcerative colitis (UC). We assessed the reliability of existing EUS indices and correlated them with endoscopic and histologic scores. METHODS: Four blinded endosonographers assessed 58 endoscopic and EUS videos in triplicate, from patients with UC. Intrarater and interrater reliability of the hyperemia and Tsuga scores were estimated by using intra-class correlation coefficients (ICCs). Correlation with the Mayo endoscopy score, modified Baron score (MBS), Ulcerative Colitis Endoscopic Index of Severity (UCEIS), and Geboes histopathology score (GHS) were calculated by using bootstrapping methods. A RAND consensus process led to development of standardized definitions and a revised EUS-UC score. RESULTS: ICCs for intrarater reliability were 0.76 (95% confidence interval [CI], 0.71-0.80) for the hyperemia score and 0.85 (95% CI, 0.79-0.89) for the Tsuga score. Corresponding values for interrater reliability were 0.34 (95% CI, 0.25-0.42) and 0.36 (95% CI, 0.24-0.46). Correlation between hyperemia and Tsuga scores to Mayo scoring system, MBS, UCEIS, and the GHS were 0.39 (95% CI, 0.15-0.61) and 0.28 (95% CI, 0.04-0.51), 0.38 (95% CI, 0.16-0.57) and 0.25 (95% CI, -0.01-0.48), 0.41 (95% CI, 0.16-0.62) and 0.27 (95% CI, 0.01-0.50), 0.37 (95% CI, -0.01-0.48) and 0.24 (95% CI, 0.13-0.57), respectively. The revised EUS-UC score included bowel wall thickening, depth of inflammation, and hyperemia. CONCLUSIONS: Although substantial to almost perfect intrarater agreement existed for EUS indices in UC, interrater agreement was fair. Standardization of item definitions with development of a revised evaluative instrument has potential application as an evaluative and prognostic tool for UC. (Clinical trial registration number: NCT01852760.).

Necroptosis Is Involved in CD4+ T Cell-Mediated Microvascular Endothelial Cell Death and Chronic Cardiac Allograft Rejection.

BACKGROUND: Despite advances in immunosuppressive therapies, the rate of chronic transplant loss remains substantial. Organ injury involves various forms of cell death including apoptosis and necrosis. We now recognize that early injury of cardiac transplants involves a newly described form of programmed necrotic cell death, termed necroptosis. Because this involves receptor-interacting protein (RIP) kinase 1/3, this study aimed to establish the role of RIP3 in chronic cardiac allograft rejection. METHODS: We used major histocompatibility complex class II mismatched C57BL/6N (H-2; B6) or B6.RIP3 (H-2; RIP3) mice to B6.C-H-2 (H2-Ab1; bm12) mouse cardiac transplantation. Microvascular endothelial cells (MVEC) were developed from B6 and RIP3 cardiac grafts. RESULT: CD4 T cell-mediated cardiac graft rejection is inhibited using RIP3 deficient donor grafts, with reduced cellular infiltration and vasculopathy compared with wild type cardiac grafts. Alloreactive CD4 T cell-mediated MVEC death involves TNFα, Fas ligand (FasL) and granzyme B. Although necroptosis and release of danger molecule high-mobility group box 1 are eliminated by the absence of RIP3, CD4 T cells had attenuated MVEC death through granzyme B and FasL. CONCLUSIONS: CD4 T cell-mediated MVEC death involves in TNFα, FasL and granzyme B. Necroptotic cell death and release of the danger molecule may promote inflammatory responses and transplant rejection. Although loss of RIP3 does not eliminate alloimmune responses, chronic graft injury is reduced. RIP3 is an important therapeutic target but additional granzyme and caspases inhibition is required for sufficiently improving long-term graft survival.

Attenuating Ischemia-Reperfusion Injury in Kidney Transplantation by Perfusing Donor Organs With siRNA Cocktail Solution.

BACKGROUND: Ischemia-reperfusion (I/R) injury is the major cause of delayed renal graft function in kidney transplantation. To date, there are no effective therapeutic approaches for preventing I/R injury. We previously reported that treatment of animals with small interference RNA (siRNA) would prevent warm I/R injury in nontransplant models and cold I/R injury in heart transplantation. In the present study, we further explore the feasibility of protecting grafts from extended cold I/R injury as applied to kidney transplantation by downregulating I/R-associated genes using siRNA. METHODS: Donor kidneys were intra-arterially perfused with siRNA containing solution during donor excision and preserved in siRNA containing solution. The siRNA-treated donor organs were then implanted into syngeneic recipient mice, and the 2 original kidneys were removed from the recipient. The effect of siRNA solution on extended cold I/R injury was determined by assessing renal function, histopathological change, cell apoptosis, and inflammation. RESULTS: The perfused siRNA solution knocked down the expression of complement 3, RelB, and Fas in the kidney at the mRNA and protein levels. Administration of siRNA solution reduced the levels of blood urea nitrogen and serum creatinine as compared with control groups. The siRNA cocktail decreased cell apoptosis and histopathological changes in the kidney and prolonged graft survival. The siRNA cocktail also reduced the expression of proinflammatory cytokines, IL-6, and TNFα. CONCLUSIONS: In conclusion, this is the first demonstration that perfusing donor organs with an siRNA cocktail solution can induce gene silencing in the kidney and prevent kidneys from extended cold I/R injury in kidney transplantation, highlighting the promise of the clinical application of siRNA-based therapies in the preservation of donor organs.

Hydrogen Sulfide Treatment Mitigates Renal Allograft Ischemia-Reperfusion Injury during Cold Storage and Improves Early Transplant Kidney Function and Survival Following Allogeneic Renal Transplantation.

PURPOSE: Ischemia-reperfusion injury is unavoidable during organ transplantation. Prolonged ischemia-reperfusion injury is detrimental to short-term and long-term graft function and survival. H2S is a recently characterized, endogenously produced gaseous molecule with important physiological roles that has been shown to be cytoprotective during tissue ischemia-reperfusion injury. The current study aimed to determine whether H2S could mitigate cold renal ischemia-reperfusion injury in the clinically relevant context of allogeneic renal transplantation. MATERIALS AND METHODS: Following bilateral native nephrectomy Lewis rats underwent renal transplantation with kidneys from Brown Norway donor rats that were flushed with cold (4C) standard University of Wisconsin preservation solution (University of Wisconsin preservation solution group) or cold University of Wisconsin preservation solution plus 150 µM NaHS (H2S group) solution. Kidneys were stored for 6 hours at 4C in the same solution. Recipient animals were monitored for 14 days or until sacrifice using metabolic cages to assess various parameters of renal graft function. RESULTS: H2S treatment improved early allograft survival and function, and decreased early levels of necrosis, apoptosis and Kim-1 compared to University of Wisconsin preservation solution alone. H2S treatment did not affect allograft rejection. Rather, it modulated the early allograft transcriptome to decrease the expression of renal injury, coagulation and cellular stress response genes, and increase the expression of cellular proliferation and Ifn-γ induced genes compared to University of Wisconsin preservation solution alone. CONCLUSIONS: To our knowledge our findings are the first to show that H2S protects donor kidneys against cold ischemia-reperfusion injury in the context of allogeneic renal transplantation. This potentially represents a novel cost-effective therapeutic solution to mitigate ischemia-reperfusion injury and improve the clinical outcomes of renal transplantation.

IL-37 inhibits IL-18-induced tubular epithelial cell expression of pro-inflammatory cytokines and renal ischemia-reperfusion injury.

Cytokines and chemokines produced by tubular epithelial and infiltrating cells are critical to inflammation in renal ischemia-reperfusion injury. IL-37, a newly described IL-1 family member, inhibits IL-18-dependent pro-inflammatory cytokine production by its binding to IL-18 receptors and IL-18 binding protein. The potential role of IL-37 in renal ischemia-reperfusion injury is unknown. Here we found that exposure of tubular epithelial cells to exogenous IL-37 downregulated hypoxia and the IL-18-induced expression of TNFα, IL-6, and IL-1ß. Importantly, human PT-2 tubular epithelial cells have inducible expression of IL-37. Moreover, pro-inflammatory cytokine expression was augmented in IL-37 mRNA-silenced tubular epithelial cells and inhibited by transfection with pCMV6-XL5-IL-37. In a mouse ischemic injury model, transgenic expression of human IL-37 inhibited kidney expression of TNFα, IL-6, and IL-1ß and improved mononuclear cell infiltration, kidney injury, and function. Thus, human tubular epithelial cells express the IL-18 contra-regulatory protein IL-37 as an endogenous control mechanism to reduce inflammation. Augmenting kidney IL-37 may represent a novel strategy to suppress renal injury responses and promote kidney function after renal ischemic injury and transplantation.

Natural killer cells play a critical role in cardiac allograft vasculopathy in an interleukin-6--dependent manner.

BACKGROUND: Approximately 50% of cardiac transplants fail in the long term, and currently, there are no specific treatments to prevent chronic rejection. In the clinic, donor cardiac graft ischemia time is limited to within a few hours and correlates with delayed graft function and organ failure. It is still unknown how ischemic injury negatively influences allograft function over the long term despite advances in immunosuppression therapy. METHODS: Allogeneic cardiac grafts were stored at 4 °C for 4 hr before being transplanted into T/B cell-deficient Rag(-/-) mice or T/B/natural killer (NK) cell-deficient γc(-/-)Rag(-/-) mice. Grafts were harvested 60 days after transplantation and indicators of chronic allograft vasculopathy (CAV) were quantified. RESULTS: We have found that cold ischemia of cardiac grafts induces CAV after transplantation into Rag1(-/-) mice. Interestingly, cold ischemia-induced CAV posttransplantation was not seen in T/B/NK cell-deficient γc(-/-)Rag(-/-) mice. However, cardiac grafts in γc(-/-)Rag(-/-) mice that received an adoptive transfer of NK cells developed CAV, supporting the role of NK cells in CAV development. Analysis of various cytokines that contribute to NK cell function revealed high interleukin (IL)-6 expression in cardiac grafts with CAV. In addition, IL-6-deficient cardiac grafts did not develop CAV after transplantation into allogeneic Rag(-/-) mice. CONCLUSION: These data demonstrate that cold ischemia and NK cells play critical roles in the development CAV. Natural killer cells and injured grafts may play a reciprocal role for CAV development in an IL-6-independent manner. Specific therapeutic strategies may be required to attenuate NK cell contribution to chronic cardiac rejection.