Role of the Complement System in Acute Kidney Injury: A Narrative Review

Acute kidney injury (AKI) remains a significant cause of morbidity and mortality worldwide, particularly in critically ill patients. Acute kidney injury often results from a combination of underlying conditions, such as sepsis or ischemia and nephrotoxic drugs, leading to a rapid decline in renal function. A significant proportion of AKI survivors have development of chronic kidney disease, which increases long-term health burdens. In recent years, increasing attention has been paid to the role of the immune system, particularly the complement system, in the pathophysiology of AKI. The complement system is a critical part of the innate immune response, with its activation playing a dual role in tissue damage and repair. Excessive complement activation, however, can exacerbate inflammation and tissue injury, contributing to the severity of AKI. Despite emerging research suggesting a strong link between complement activation and AKI, the extent of this relationship remains underexplored, particularly in clinical settings. In this narrative review, after a literature search using engines such as PubMed, MEDLINE, and EMBASE, we consolidated current evidence on the role of complement in AKI, examining underlying mechanisms and potential diagnostic and therapeutic interventions based on the complement system.