Belatacept Rescue Therapy in Kidney Transplant Recipients With Vascular Lesions: A Case Control Study

Immunosuppression in kidney transplant recipients with decreased graft function and severe histological vascular changes can be particularly challenging. Belatacept could be a valuable option, as a rescue therapy in this context. We report a retrospective case control study comparing a CNI to belatacept switch in 17 patients with vascular damage and low eGFR to a control group of 18 matched patients with CNI continuation. Belatacept switch was performed on average 51.5 months after kidney transplantation (6.2-198 months). There was no difference between the two groups regarding eGFR at inclusion, and 3 months before inclusion. In the "CNI to belatacept switch group," mean eGFR increased significantly from 23.5 ± 6.7 mL/min/1.73m² on day 0, to 30.4 ± 9.1 mL/min/1.73 m² on month 6 (p < 0.001) compared to the control group, in which no improvement was observed. These results were still significant on month 12. Two patients experienced biopsy-proven acute rejection. One was effectively treated without belatacept discontinuation. Two patients needed belatacept discontinuation for infection. In conclusion, the remplacement of CNI with belatacept in patients with decreased allograft function and vascular lesions is associated with an improvement in eGFR.

Immune Reconstitution Inflammatory Syndrome Secondary to Mycobacterium kansasii Infection in a Kidney Transplant Recipient

Nontuberculous mycobacteria (NTM) infection is a challenging diagnosis for clinicians in solid organ transplantation. Immune reconstitution inflammatory syndrome (IRIS) is so far unreported in this context. We report here the case of a renal transplant recipient who developed Mycobacterium kansasii-associated lymphadenitis complicated by IRIS while undergoing reduction of his immunosuppressive therapy. For IRIS, the patient required low-dose steroids and an increase in global immunosuppression, in association with NTM antibiotherapy.

Recurrent membranous nephropathy in an allograft caused by IgG3κ targeting the PLA2 receptor

Up to 80% of patients with idiopathic membranous nephropathy have non-complement-fixing IgG4 autoantibodies to the phospholipase A2 receptor (PLA2R). Membranous nephropathy recurs in approximately 40% of patients after kidney transplantation, but the mechanism is unknown. Here, we describe a patient with recurrent membranous nephropathy 13 days after kidney transplantation whose graft biopsy specimen showed granular staining for C3, C5b-9, C1q, and IgG3κ; electron microscopy revealed subepithelial nonorganized deposits. A search for hematologic disorders was negative. Retrospective evaluation of a biopsy sample from the native kidney revealed a similar pattern: monotypic IgG3κ deposits together with C3, C1q, and C5b-9. Glomerular deposits contained PLA2R in both the graft and the native kidney, suggesting that the recurrence was the result of circulating anti-PLA2R antibodies binding to PLA2R antigen expressed on donor podocytes. Confocal analysis of anti-PLA2R and antihuman IgG3 showed co-localization, and the patient had IgG3κ-restricted circulating anti-PLA2R antibodies. Treatment with rituximab stabilized both proteinuria and serum creatinine, and circulating anti-PLA2R became undetectable. In summary, this case of recurrent membranous nephropathy in a graft suggests that circulating monoclonal anti-PLA2R IgG3κ caused the disease and activated complement by the classic pathway.

Nephroangiosclerosis in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: is NOTCH3 mutation the common culprit?

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a systemic arterial disease characterized by impairment of vascular smooth muscle cell structure and function related to NOTCH3 mutations. Pathological findings include pathognomonic granular osmiophilic material (GOM) deposition with nonspecific hyalinization within the artery wall in a variety of tissues. The main clinical presentation is iterative strokes in young adults despite the lack of cardiovascular risk factors, leading to early dementia. Although arteriosclerosis and GOM have been found in kidneys from patients with CADASIL, kidney disease has been described only once up to now, in association with immunoglobulin A nephropathy. We report the case of a 61-year-old patient with a medical history of CADASIL and recent mild hypertension. His mother also showed neuropsychiatric symptoms and end-stage renal disease of unknown cause. The patient had a chronic kidney disease defined by means of estimated glomerular filtration rate using the 4-variable Modification of Diet in Renal Disease Study equation of 58 mL/min/1.73 m(2) associated with mild proteinuria and intermittent microscopic hematuria. Renal histological analysis showed severe arteriosclerosis and mild interstitial fibrosis. Glomeruli did not show mesangial immunoglobulin A deposition or focal segmental proliferation. Electron microscopic analysis showed typical GOM deposition in the vicinity of altered vascular smooth muscle cells in interlobular and juxtaglomerular arteries. The nephroangiosclerosis-like lesions were unusually severe in contrast to the recent mild hypertension. The presence of GOM strongly suggests that renal lesions were related to the NOTCH3 mutation. Here, we describe the first case of familial occurrence of kidney disease with decreased kidney function in the absence of coexisting nephropathy in patients with CADASIL. We discuss the role of NOTCH3 mutation in the pathogenesis of nephroangiosclerosis through functional impairment of renal microcirculation or primary Notch3-related vascular disease.