Recent studies discovered the prominent presence of anti-nephrin autoantibodies in minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). However, widely different and often unconventional autoantibody detection methods were used in these studies, making it challenging to standardize anti-nephrin antibody detection and quantification across different studies. Here, we compare methods of conventional ELISA, immunoprecipitation (IP)-based on-beads ELISA, immunoprecipitation-Western blotting (IP-WB), and cell- and tissue-based immunofluorescence staining with two cohorts totaling 169 patients and control individuals. Different assay methods and antigen preparations led to method-specific false-positive and false-negative results. In general, high-quality antigens produced in human cells, combined with IP-based assays, yielded the most robust and reliable results. Among 63 and 24 samples from patients with FSGS or MCD, respectively, two patients with FSGS showed strong antibody signals in both ELISA-based assays and IP-WB, while approximately half of patients with MCD had weak signals detectable only by IP-WB. These findings highlight the importance of standardizing antibody detection methods.

Background: Acute rejection (AR) in kidney transplant (KT) recipients remains a significant challenge for short- and long-term graft survival even in the most recent years characterized by extended criteria donors and older and more comorbid recipients. Methods: We analyzed risk factors and outcomes of AR in 339 KT recipients treated at St. Orsola-Malpighi Hospital, Bologna (Italy), between 1 January 2019 and 31 December 2021. Demographic, immunological, and transplant data (type, cold ischemia time, complications) were recorded with a follow-up period of up to 24 months. Key outcomes included estimated glomerular filtration rate (eGFR), 24 h proteinuria, delayed graft function (DGF), biopsy-proven AR, and graft loss. Results: During the first year after transplant, 57 AR episodes occurred: 19 antibody-mediated rejections (AMR), 18 borderline T cell-mediated rejections (TCMR), 18 TCMR, 2 mixed AMR/TCMR, and 11 graft losses. AR was linked to older donor age (59.9 ± 12.8 vs. 55.5 ± 15.1, p = 0.040), longer cold ischemia time (690 vs. 570 min, p = 0.044), higher DGF rates (61.40% vs. 39.57%, p = 0.002), and lower eGFR (39 vs. 52 mL/min, p = 0.003). AR was consistently prevalent in patients who underwent an AB0-incompatible (AB0-i) transplant (8.8% vs. 2.5%, p = 0.020). HLA matching was strongly associated with a reduced risk of AMR (HLA-DR: OR 0.35, HLA-A: OR 0.33, HLA-C: OR 0.35), while DGF was linked to a higher risk (OR 4.04). TCMR risk was associated with donor age (OR 1.05). The development of post-transplant donor-specific antibodies (DSAs) at 24 months showed no significant association with AR (AMR: p = 0.769; TCMR: p = 0.938). The decline in eGFR over time (24 months) did not differ between patients with and without AR (difference, −0.69 mL/min/year; Standard Error, 0.92; p = 0.452). Similarly, 24 h proteinuria change over time did not differ between patients with and without AR (difference, −0.12 g/24 h; Standard Error, 0.28; p = 0.657). Conclusions: Understanding the risk factors of AR is crucial to identifying KTs at more risk of rejection and to guiding targeted therapeutic decisions. In the most recent era of extended criteria donors and more vulnerable recipients, early diagnosis and prompt and tailored treatment of AR play a critical role in stabilizing renal function over time.

Kidney transplantation is a lifesaving procedure for patients with end-stage kidney disease (ESKD). Organs derived from donation after cardiac death (DCD) are constantly increasing; however, DCD often leads to ischaemia-reperfusion (IR) and Acute Kidney Injury (AKI) events. These phenomena increase kidney cell turnover to replace damaged cells, which are voided in urine. Urine-derived renal epithelial cells (URECs) are rarely present in the urine of healthy subjects, and their loss has been associated with several kidney disorders. The present study aimed to characterize the phenotype and potential applications of URECs voided after transplant. The results indicate that URECs are highly proliferating cells, expressing several kidney markers, including markers of kidney epithelial progenitor cells. Since the regulation of the immune response is crucial in organ transplantation and new immunoregulatory strategies are needed, UREC immunomodulatory properties were investigated. Co-culture with peripheral blood mononuclear cells (PBMCs) revealed that URECs reduced PBMC apoptosis, inhibited lymphocyte proliferation, increased T regulatory (Treg) cells and reduced T helper 1 (Th1) cells. URECs from transplanted patients represent a promising cell source for the investigation of regenerative processes occurring in kidneys, and for cell-therapy applications based on the regulation of the immune response.

Background.: Focal segmental glomerulosclerosis (FSGS) recurrence after kidney transplantation is a leading cause of allograft failure and remains difficult to treat. Standard therapies, including plasma exchange (PEX) and rituximab, are often ineffective and poorly tolerated. Growing evidence implicates immune-mediated circulating factors, such as IgG and IgM autoantibodies, in disease pathogenesis. Given the central role of memory B cells and plasma cells in antibody production, we tested the safety/efficacy profile of a combined B-cell and plasma cell–depleting approach with rituximab and daratumumab in patients with posttransplant FSGS recurrence. Methods.: This is a retrospective analysis of a multicenter, international cohort of sixteen patients (median age 37 y) with biopsy-proven FSGS recurrence posttransplant who received anti-CD20 plus anti-CD38 monoclonal antibodies or anti-CD38 alone. The majority of patients were resistant to common therapies, including rituximab and PEX. Results.: The treatment achieved complete or partial remission in 5 and 11 patients, respectively. Five experienced proteinuria relapse, and 4 responded to repeated daratumumab alone. At the last follow-up (median 11 [2–18] mo), 13 patients are still in remission and PEX was discontinued in all but 3 cases. Overall, kidney function improved after treatment, and no severe acute or chronic adverse events were reported. Serological analysis revealed a significant decline in IgM, but not in IgG, after treatment. Conclusions.: Despite the retrospective, nonrandomized design, the temporal association between treatment and remission supports an effect of anti-CD38 monoclonal antibody alone or in combination with anti-CD20. Treatment is safe and may confer enhanced efficacy over standard approaches. Prospective, mechanistic studies are warranted to validate these findings and delineate the immunopathogenesis of FSGS recurrence.

Chronic kidney disease (CKD) is a widespread condition with significant cardiovascular risks and a progression to end-stage kidney failure. In recent years, increasing attention has been paid to the role of dietary interventions as a factor capable of influencing disease trajectory. This review summarizes the current observational and interventional evidence on various dietary approaches in patients with CKD and kidney transplants (KTs), including Mediterranean, plant-based, and low-protein diets. A balanced Mediterranean diet, rich in fruits, vegetables, whole grains, fish, and unsaturated fats, shows promises in improving the prognosis for CKD patients. Plant-based diets, which emphasize legumes, vegetables, and grains while minimizing animal protein, improve blood pressure and the glycemic and lipid control. Low-protein diets (LPDs), typically providing less than 0.6 g/kg/day of protein, may reduce the CKD progression and nitrogen burden, further delaying the initiation of dialysis. In conclusion, diets represent a valuable and underutilized therapeutic strategy in the management of CKD and KTs, influencing disease progression and patient outcomes.