Protecting the kidney and remote organs following renal ischemia

Rlr Va Medical Center, Indianapolis IN

Investigators

Linked publications & trials

Abstract

Ischemic injury to the kidney and other organs is deadly and expensive. Ischemic acute kidney injury (AKI) occurs in up to two thirds of intensive care patients and 1 in 5 hospitalized adults with ~1.7 million of these patients dying annually. The very high mortality in AKI, however, is NOT caused by renal failure per se. Epidemiological and clinical data support the critical role of AKI-associated distant organ dysfunction in poor outcomes and mortality in AKI. AKI also can result in chronic kidney disease (CKD), progression of CKD to end stage renal disease (ESRD) and kidney transplant failure. While AKI and CKD are onerous, the transition to ESRD can be particularly perilous; mortality rates in Veterans (~40%) are huge in the first 90 days of ESRD care. AKI has no current treatment; thus, effective AKI therapy is an important unmet medical need. The robust, prompt inflammatory and oxidative stress response to renal ischemia has been well documented by others and by us. Inflammation in remote organs has also been found after renal ischemia, but the “crosstalk” between the injured kidney and remote organs is also not well understood. With Merit Review funding, we have demonstrated the effectiveness of adult-cell based therapies in multiple models of renal failure. Given the large benefits of relatively few cells, we hypothesized that extracellular vesicles (EV or exosomes), a non-viral biologic, released from the transplanted cells were the therapeutic effector. We found that renal EV were more effective than the originating cells, decreasing inflammation and oxidative stress and improving renal function postischemia, even when given after renal failure was established. Others have shown benefit with EV in renal injury models. We now propose to define the anti-inflammatory and anti-oxid- ant effects of renal EV in the kidney and remote organs and determine the specific therapeutic cargo. Our long-term goal is the development of effective therapies to improve outcomes in Veterans with renal insults. Our objective in this proposal is defining key mediators of benefit (including anti-inflammatory and anti-oxidative molecules) in the kidney and remote organs that are improved by EV and determine the “active ingredients” in EV cargo. Our central hypotheses are that renal EV provide a multi-faceted therapy for renal ischemic injury, increasing renal superoxide and catalase and anti-inflammatory cytokines and that skin and platelet EV do not decrease inflammation and are not protective. This will allow us to define the specific beneficial cargo in renal EV. We will employ the powerful technique of spatial transcriptomics to examine the changes with ischemia and improvements with EV. Furthermore, we posit that systemic and remote organ inflammation result from ischemia and not uremia and can be improved with EV. Based on our preliminary data, we propose the following aims to fill knowledge gaps in the mechanisms of renal injury and protection: 1. To define the efficacy of extracellular vesicles from different sources on postischemic renal function, inflammation and oxidative stress. Preliminary data support efficacy of renal, but not platelet or skin EV. We will examine means (including ischemic preconditioning) to improve efficacy. We will also compare cargo and the effects on pathways of ischemic injury between beneficial renal EV and ineffective EV in order to define the essential therapeutic cargo components and most altered pathways of renal injury. 2. To determine the effect of renal ischemia on inflammation and oxidative stress in remote organs and the effect of EV on inflammation and organ function following renal ischemia. At the conclusion of this work, we expect to have defined the key inflammatory and oxidative stress mediators of ischemic renal injury, the effects of renal ischemia on inflammation in remote organs, other specific mechanisms of benefit postischemia and the EV cargo that improve inflammation and renal function. The results are expected to have a significant positive impact in that they will provide the strong evidence- based proof of principle for further development of potential therapies to improve outcomes in AKI.