Ischemia/reperfusion injury (IRI) is a major clinical problem associated with several clinical conditions (e.g., hemorrhagic shock, severe burns, sepsis, myocardial infarction, stroke, transplant dysfunction/rejection). Complement is known to play a key role in sterile inflammation and injury following ischemia and reperfusion (IR), but more recently it has become evident that complement also plays important roles in tissue repair and regeneration following certain ischemic events. A goal of the proposed studies is to better understand the complement activation event following IR, and to dissect the dual role of complement effector mechanisms in IRI and tissue repair/regeneration. Concurrent with these goals, it is proposed to develop and characterize a novel targeted complement inhibitory strategy that protects against inflammation and injury while promoting tissue repair and regeneration. Previous and preliminary data indicate similar complement activation and effector mechanisms are involved in the injury and repair/regeneration processes of multiple organs and tissues. However, our model will be hepatic IRI and regeneration since mouse models have been well characterized and because of clinical significance. The overall working hypothesis is that complement is activated by natural self-reactive IgM that binds to neoepitopes exposed after ischemia, and that the terminal membrane attack complex (MAC) plays a key role in ischemia reperfusion injury (IRI) whereas more proximal activation products are important for repair and regeneration. We have isolated a panel of novel self-reactive IgM mAbs, and will use these mAbs to investigate immunological changes (neoepitope exposure) and the complement activation event that occurs after either IR or partial hepatectomy. We will also utilize complement inhibitors that function at different points in the cascade to investigate complement effector mechanisms involved in inflammation, injury and regeneration. We will also investigate the role of complement in phagocytic clearance of apoptotic and necrotic cells, and how this process impacts the inflammatory environment and subsequent tissue injury and repair. Finally, we will investigate how data generated in our mouse models relates to humans by analysis of clinical specimens. An additional goal of these studies is to develop a novel targeting strategy tolocally deliver a complement inhibitor to post-ischemic neoepitopes utilizing single chain antibodies.

Public Health Relevance

Ischemia/reperfusion injury (IRI) is a major clinical problem associated with clinical conditions involving vascular occlusion resulting from, for e.g., hemorrhagic shock, severe burns, sepsis, myocardial infarction and stroke. IRI is also an unavoidable event occurring during organ transplantation and various surgeries. The long-term goal of this project is to develop a therapeutic strategy to safely and effectively treat IRI and t promote tissue repair and recovery in order to improve outcome of the above disease conditions and to improve organ survival after transplantation.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
High Priority, Short Term Project Award (R56)
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Innate Immunity and Inflammation Study Section (III)
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Nasseri, M Faraz
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Medical University of South Carolina
Schools of Medicine
United States
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Marshall, Keely; Jin, Junfei; Atkinson, Carl et al. (2017) Natural immunoglobulin M initiates an inflammatory response important for both hepatic ischemia reperfusion injury and regeneration in mice. Hepatology :
Marshall, Keely M; He, Songqing; Zhong, Zhi et al. (2014) Dissecting the complement pathway in hepatic injury and regeneration with a novel protective strategy. J Exp Med 211:1793-805
Atkinson, Carl; Floerchinger, Bernhard; Qiao, Fei et al. (2013) Donor brain death exacerbates complement-dependent ischemia/reperfusion injury in transplanted hearts. Circulation 127:1290-9
Elvington, Andrew; Atkinson, Carl; Zhu, Hong et al. (2012) The alternative complement pathway propagates inflammation and injury in murine ischemic stroke. J Immunol 189:4640-7