The syndromes of thrombotic microangiopathy: towards a true etiology-based approach

This thesis investigated the role of innate immunity in patients with microvascular thrombosis in the kidneys, that is, thrombotic microangiopathy (TMA). TMA indicates a pathologic diagnosis that can be caused by diverse mechanisms, including but not limited to overactivation of innate immunity. The recognition of the underlying mechanism, although challenging, is of utmost clinical importance to guide treatment decisions. This thesis shows that overactivation of complement, which plays an important role in innate immunity, is common along the spectrum of TMA. This, in particular, is the case in patients who rapidly progress to end-stage kidney disease. A novel in-house developed blood test and genotyping can be used to differentiate so-called complement-mediated TMA from other causes, having major impact on treatment and prognosis. Kidney survival, indeed, was 12-fold higher in patients who had been treated with therapeutic complement inhibition as compared to untreated patients. The results of this thesis have changed the landscape of TMAs as knowledge on the role of complement has enabled breakthroughs in diagnosis and treatment. Further progress can be expected in the coming years.