Macrophage activation syndrome: a review of recent renal findings

The pathogenesis of Macrophage activation syndrome consists of excessive macrophage and T-cell activation, leading to the uncontrolled release of cytokines and chemokines, which can cause multi-organ dysfunction. The diagnostic criteria for MAS include fever, splenomegaly, cytopenia, hypertriglyceridemia and/or hypofibrinogenemia, hemophagocytosis, low or absent natural killer cell activity, elevated ferritin levels, and elevated soluble interleukin-2 receptor levels. Kidney involvement in this disease included glomerular changes, including mesangial expansion, endocapillary proliferation, and thrombotic microangiopathy. Renal biopsy in MAS may also show evidence of macrophage infiltration and activation, such as the presence of hemophagocytic macrophages within the glomeruli and interstitium. These macrophages may contain phagocytosed erythrocytes, platelets, and other cells, indicating ongoing hemophagocytosis. The presence of hemophagocytic macrophages on renal biopsy is highly suggestive of MAS and can help differentiate it from other causes of acute kidney injury (AKI). Management of macrophage activation syndrome-associated kidney involvement involves treating the underlying autoimmune disorder and controlling the systemic inflammation. This may include the use of immunosuppressive medications, such as corticosteroids, disease-modifying anti-rheumatic drugs, and biological agents. Supportive measures, such as renal replacement therapy, may be necessary in severe cases of renal dysfunction.