Platelets are not critical effector cells for the time course of murine passive crescentic glomerulonephritis

Extreme Thrombocytosis Presenting in Anti-Neutrophil Cytoplasmic Autoantibodies-Associated Crescentic Glomerulonephritis with Immune Complex Deposits: A Case Report

INTRODUCTION

We describe a female patient with extreme reactive thrombocytosis (RT) in anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated crescentic glomerulonephritis (CGN) with immune complex deposits, which has never been reported before.

CASE PRESENTATION

A female adolescent with symptoms of oliguria and gross hematuresis had serious renal function impairment (crescent formation and immune complex deposits in renal pathology examination with positive serum ANCA) and extreme thrombocytosis. We made a diagnosis of CGN and RT. After treatment with Prednisone, Cyclophosphamide, and plasmapheresis, the symptoms of oliguria and gross hematuresis were relieved remarkably and the serum creatinine and platelet count declined significantly.

CONCLUSIONS

The diagnosis of thrombocytosis is not easy in all cases. The coexistence of ANCA and the immune complex in CGN may cause a severe inflammatory state, leading to extreme RT. The roles that the immune complex and ANCA play on the effect of the platelet count and function in CGN need further research.

Platelets are relevant mediators of renal injury induced by primary endothelial lesions

Several studies have suggested a prominent (pro)inflammatory and harmful role of platelets in renal disease, and newer work has also demonstrated platelet release of proangiogenic factors. In the present study, we investigated the role of platelets in a mouse model of selective endothelial cell injury using either platelet depletion or the pharmacological P2Y12 receptor blocker clopidogrel as an interventional strategy. The concanavalin A/anti-concanavalin A model was induced in left kidneys of C57bl/6J wild-type mice after initial platelet depletion or platelet-inhibiting therapy using clopidogrel. FACS analysis of glycoprotein IIb/IIIa/P-selectin double-positive platelets and platelet-derived microparticles demonstrated relevant platelet activation after the induction of selective endothelial injury in mice. Enhanced platelet activation persisted for 5 days after disease induction and was accompanied by increased amounts of circulating platelet-derived microparticles as potential mediators of a prolonged procoagulant state. By immunohistochemistry, we detected significantly reduced glomerular injury in platelet-depleted mice compared with control mice. In parallel, we also saw reduced endothelial loss and a consequently reduced repair response as indicated by diminished proliferative activity. The P2Y12 receptor blocker clopidogrel demonstrated efficacy in limiting platelet activation and subsequent endothelial injury in this mouse model of renal microvascular injury. In conclusion, platelets are relevant mediators of renal injury induced by primary endothelial lesions early on, as demonstrated by platelet depletion as well as platelet inhibition via the P2Y12 receptor. While strategies to prevent platelet-endothelial interactions have shown protective effects, the contribution of platelets during renal regeneration remains unknown.