RIPK3-Mediated Necroptosis Promotes Donor Kidney Inflammatory Injury and Reduces Allograft Survival

Abstract

Kidney transplant injury occurs with ischemia and alloimmunity. Members of the receptor interacting protein kinase family (RIPK1,3) are key regulators of “necroptosis,” a newly recognized, regulated form of necrosis. Necroptosis and apoptosis death appear to be counterbalanced as caspase‐8 inhibition can divert death from apoptosis to necrosis. Inhibition of necroptosis in donor organs to limit injury has not been studied in transplant models. In this study, necroptosis was triggered in caspase inhibited tubular epithelial cells (TEC) exposed to tumor necrosis factor alpha in vitro, while RIPK1 inhibition with necrostatin‐1 or use of RIPK3−/− TEC, prevented necroptosis. In vivo, short hairpin RNA silencing of caspase‐8 in donor B6 mouse kidneys increased necroptosis, enhanced high‐mobility group box 1 release, reduced renal function and accelerated rejection when transplanted into BALB/c recipients. Using ethidium homodimer perfusion to assess necrosis in vivo, necrosis was abrogated in RIPK3−/− kidneys postischemia. Following transplantation, recipients receiving RIPK3−/− kidneys had longer survival (p = 0.002) and improved renal function (p = 0.03) when compared to controls. In summary, we show for the first time that RIPK3‐mediated necroptosis in donor kidneys can promote inflammatory injury, and has a major impact on renal ischemia–reperfusion injury and transplant survival. We suggest inhibition of necroptosis in donor organs may similarly provide a major clinical benefit.

Exogenous Lipocalin 2 Ameliorates Acute Rejection in a Mouse Model of Renal Transplantation

“…One might also infer that the mitochondrial permeability transition–blocking potential of CsA would result in reduced inflammatory response, reduced regulated necrosis and better overall graft survival 51, 52. Comparing kidney isografts with allografts indicates, as expected, a mild contribution of alloantigen‐independent IRI because cold and warm ischemia were maintained for a minimum of 40 and 30 min, respectively.…”

CXCR4 antagonism as a therapeutic approach to prevent acute kidney injury

“…Various cell death pathways are activated in renal IRI, including apoptosis and regulated necrosis. The latter includes mitochondrial permeability transition (42), necroptosis (36,42,43), and pyroptosis (63). TUNEL staining, which detects DNA fragmentation and has been used to measure apoptosis, can also be an indicator of necrotic cell death (42,44).…”

Necroinflammation in Kidney Disease

“…76 Acute Tubular Necrosis Ex vivo microscopy (high-resolution microscopy of freshly isolated primary kidney tubules) revealed how single-cell necrosis can spread on neighboring cells so that the entire tubule segment undergoes a synchronized cell death. 35,77,78 Whether synchronized necrosis occurs in vivo has yet to be demonstrated. Regulated tubule necrosis is not limited to Table 2).…”