The Presence of Renal IgG Deposits in Necrotizing Crescentic Glomerulonephritis Associated with ANCA Is Not Related to Worse Renal Clinical Outcomes

International audienceIntroduction:Diagnosing the etiology of a rapidly progressive glomerulonephritis is of vital importance to guide appropriate therapeutic management. This case highlights the complexity involved in establishing diagnosis when presentation is atypical. In certain cases diagnosis cannot be established based on clinical presentation or biopsy findings alone, and critical analysis of biopsy findings in context of clinical presentation is crucial to guide the clinical decision-making process.Case presentation: A 47-year-old Hispanic male with history of granulomatosis with polyangiitis (GPA) in remission on azathioprine, presented with fatigue and lethargy. Physical examination was unremarkable. Laboratory data revealed elevated creatinine and otherwise normal electrolytes. Urinalysis showed numerous dysmorphic red blood cells with few red cell casts. His serologic results were all negative except anti-proteinase-3 antibody at very low titers. Kidney biopsy showed necrotizing crescentic glomerulonephritis with linear immunoglobulin G staining along the basement membrane.Conclusion: This case presented conflicting serologic and histopathologic findings. The presence of anti-proteinase-3 antibody supported diagnosis of recurrence of GPA. However, linear staining of immunoglobulin G (IgG) on immunofluorescence (IF) staining of renal biopsy supported anti-glomerular basement membrane (GBM) disease. The treatment of anti-GBM disease and GPA both involve immunosuppression with prednisone and cyclophosphamide. However, patients with anti-GBM disease are also treated with plasmapheresis early in the disease presentation to prevent further damage. The patient with GPA, on the other hand, was shown to benefit from plasmapheresis only in the case of severe renal disease (serum creatinine level more than 5 mg/dL) or pulmonary hemorrhage. In this case, since the patient did not have detectable circulating anti-GBM antibody, the decision was made not to proceed with plasmapheresis. The patient was treated with a standard immunosuppressive regimen consisting of prednisone and cyclophosphamide with partial renal recovery at 2 months

Anti-CD28 Antibody and Belatacept Exert Differential Effects on Mechanisms of Renal Allograft Rejection

International audienceBelatacept is a biologic that targets CD80/86 and prevents its interaction with CD28 and its alternative ligand, cytotoxic T lymphocyte antigen 4 (CTLA-4). Clinical experience in kidney transplantation has revealed a high incidence of rejection with belatacept, especially with intensive regimens, suggesting that blocking CTLA-4 is deleterious. We performed a head to head assessment of FR104 (n=5), a selective pegylated Fab9 antibody fragment antagonist of CD28 that does not block the CTLA-4 pathway, and belatacept (n=5) in kidney allotransplantation in baboons. The biologics were supplemented with an initial 1-month treatment with low-dose tacrolimus. In cases of acute rejection, animals also received steroids. In the belatacept group, four of five recipients developed severe, steroid-resistant acute cellular rejection, whereas FR104-treated animals did not. Assessment of regulatory T cell-specific demethylated region methylation status in 1-month biopsy samples revealed a nonsignificant trend for higher regulatory T cell frequencies in FR104-treated animals. Transcriptional analysis did not reveal significant differences in Th17 cytokines but did reveal higher levels of IL-21, the main cytokine secreted by CD4 T follicular helper (Tfh) cells, in belatacept-treated animals. In vitro, FR104 controlled the proliferative response of human preex-isting Tfh cells more efficiently than belatacept. In mice, selective CD28 blockade also controlled Tfh memory cell responses to KLH stimulation more efficiently than CD80/86 blockade. Our data reveal that selective CD28 blockade and belatacept exert different effects on mechanisms of renal allograft rejection, particularly at the level of Tfh cell stimulation