INTRODUCTION:The persistent shortage of transplantable kidneys has increased reliance on marginal organs, yet kidneys with advanced chronic lesions on pre-implantation biopsy are frequently discarded. Dual kidney transplantation (DKT) may mitigate this risk by increasing nephron mass, but outcomes of allografts with very high histological scores remain poorly defined. We evaluated kidney transplant outcomes according to transplant type and pre-implantation Karpinski score, with particular focus on DKT using kidneys with combined Karpinski score ≥9. METHODS:We conducted a retrospective cohort study of 262 adult deceased-donor kidney transplant recipients undergoing pre-implantation biopsy at a single Italian center between 2014 and 2021. Recipients were stratified into 3 allocation groups: single kidney transplantation with Karpinski score <9 (SKT <9), DKT with combined Karpinski score <9 (DKT <9), and DKT with combined Karpinski score ≥9 (DKT ≥9). Primary outcomes were post-transplant eGFR and proteinuria during follow-up. Secondary outcomes included delayed graft function (DGF), acute rejection, complications, overall graft failure, all-cause mortality, and death-censored graft failure. RESULTS:Among 262 recipients, 142 received SKT <9, 35 received DKT <9, and 85 received DKT ≥9. DKT donors were older and had higher KDPI/KDRI than SKT donors. Despite greater histological chronicity, recipients of DKT ≥9 grafts did not show inferior renal function at longer-term follow-up, with comparable eGFR and proteinuria at 12 and 36 months. Primary non-function, DGF, biopsy-proven acute rejection, and major complications were similar across groups, although post-transplant thrombotic microangiopathy was more frequent in DKT recipients. Kaplan-Meier analyses showed no significant differences in overall graft failure, all-cause mortality, or death-censored graft failure. In multivariable Cox regression, allocation group was not independently associated with overall graft failure. CONCLUSION:In this real-world allocation cohort, kidneys with combined Karpinski score ≥9 achieved outcomes comparable to lower-score grafts when allocated as DKT. These findings support the use of DKT as a strategy to safely expand the donor pool and suggest that high histological chronicity should not automatically preclude transplantation when integrated with clinical and functional donor assessment.

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.

ObjectiveThe role of complement in the long-term renal survival of patients with lupus nephritis (LN) remains poorly understood. Recent studies suggest its potential impact; however, long-term data are lacking.MethodsThis multicenter, observational, retrospective study aimed at investigating the influence of complement levels on long-term renal outcomes in LN patients. We evaluated whether isolated C3 hypocomplementemia (i-LowC3), defined as serum low C3 (≤80 mg/dL) and normal C4 (>10 mg/dL) six months after kidney biopsy is associated with subsequent risk of chronic kidney disease (CKD), End Stage Kidney Disease (ESKD) or death.Results445 patients with LN were studied (median follow-up 4.9 years). Based on six-month C3/C4 levels, patients were categorized into i-LowC3 (91 patients) and controls (354 patients). Over the first six months, serum C3 and C4 levels increased by a median of 20 mg/dL and 5 mg/dL, respectively. i-LowC3 was significantly associated with twice the risk of a poor outcome, including CKD, ESKD, composite outcome of CKD or death and ESKD or death, with lower survival rates for all these outcomes compared to controls (P < 0.001). Multivariate Cox regression analysis revealed a lower risk of CKD and CKD or death with increases in C3 levels during the first six months, while i-LowC3 was associated with an independent higher risk for these outcomes.ConclusionThe trajectory of serum C3 levels within the first six months appears to predict long-term renal prognosis of LN patients. These findings support the use of i-LowC3 as a low-cost, readily available biomarker to guide early treatment of LN patients.

Membranous nephropathy (MN) is a leading cause of kidney failure worldwide and frequently recurs after transplant. Available data originated from small retrospective cohort studies or registry analyses; therefore, uncertainties remain on risk factors for MN recurrence and response to therapy. Within the Post-Transplant Glomerular Disease Consortium, we conducted a retrospective multicenter cohort study examining the MN recurrence rate, risk factors, and response to treatment. This study screened 22,921 patients across 3 continents and included 194 patients who underwent a kidney transplant due to biopsy-proven MN. The cumulative incidence of MN recurrence was 31% at 10 years posttransplant. Patients with a faster progression toward end-stage kidney disease were at higher risk of developing recurrent MN (hazard ratio [HR], 0.55 per decade; 95% confidence interval [CI], 0.35-0.88). Moreover, elevated pretransplant levels of anti-phospholipase A2 receptor (PLA2R) antibodies were strongly associated with recurrence (HR, 18.58; 95% CI, 5.37-64.27). Patients receiving rituximab for MN recurrence had a higher likelihood of achieving remission than patients receiving renin-angiotensin-aldosterone system inhibition alone. In sum, MN recurs in one-third of patients posttransplant, and measurement of serum anti-PLA2R antibody levels shortly before transplant could aid in risk-stratifying patients for MN recurrence. Moreover, patients receiving rituximab had a higher rate of treatment response.

PURPOSE:Anastomotic pseudoaneurysms of transplanted kidneys are a very rare complication encountered in less than 1% of cases. They may be devastating, leading to functional impairment, kidney transplantectomy, or death. Treatment has not been standardized, with open surgical repair considered the safest procedure even if it is often complicated by bleeding and graft loss. The purpose of this case report is to describe an endovascular treatment of this condition, consisting of the combination of coil embolization and arterial stenting.CASE REPORT:A 61-year-old woman developed an anastomotic pseudoaneurysm 2 months after kidney transplantation, causing acute kidney injury related to ab-extrinsic stenosis of the transplant renal artery (TRA) and external iliac artery. The pseudoaneurysm was successfully treated by coil embolization, and the arterial patency was restored by the stenting of TRA and external iliac artery. The patient completely recovered kidney function, and after a 6-month-follow-up, creatinine values were stable with normal renal perfusion.CONCLUSION:Endovascular repair through coil embolization and TRA stenting can be a safe and effective option to treat anastomotic pseudoaneurysm in kidney transplant.

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.

Introduction:Posttransplant thrombotic microangiopathy (PT-TMA) is an uncommon event that characterizes approximately 3% to 14% of kidney transplants (KTs), and that is associated with a higher risk of delayed graft function and graft loss. PT-TMA occurs more frequently within the first 3 months after transplant and can be a manifestation of de novo disease or the recurrence of previous atypical hemolytic uremic syndrome (aHUS). Abnormalities in complement regulation genes could explain the increased susceptibility of some patients to PT-TMA. Eculizumab is a humanized monoclonal antibody that inhibits the formation of the membrane attack complex C5b-9. The aim of this study is to evaluate the efficacy of eculizumab as treatment for PT-TMA.Methods:We retrospectively analyzed clinical records of 45 KT patients who received eculizumab immediately after the clinical diagnosis of PT-TMA.Results:Kidney biopsy was performed in 91.1% of patients, and complement genetic study was performed in 64.4%. Of the kidney biopsies, 85.4% showed signs of TMA; genetic analysis revealed 1 pathogenetic variant, 2 variants of uncertain significance, 1 likely benign variant, 8 risk polymorphisms, and 27 risk haplotypes. After 2 weeks from the treatment starting, hemoglobin and platelets significantly increased. A remarkable improvement in kidney function was also observed. After 6 months, 28.8% of patients had a complete renal recovery whereas 44.4% had a partial recovery.Conclusion:This is, to our knowledge, the largest series of KT patients with PT-TMA treated with eculizumab. These data suggest that eculizumab is associated with a normalization of hemolysis indices and an important and progressive improvement of graft function.

Background Diabetic donors are recognized as a reliable source of organs, although the discard rate of kidneys is still high. Few data are available on the histological evolution of these organs especially on kidneys transplanted into non-diabetic patients who remain euglycemic. Methods We describe the histological evolution of ten kidney biopsies performed on non-diabetic recipients of diabetic donors. Results Mean donor age was 69 ± 7 years, 60% were males. Two donors were treated with insulin, eight with oral antidiabetic drugs. Mean recipient age was 59.9 ± 7 years, 70% were males. The pre-existing diabetic lesions identified in the pre-implantation biopsies, encompassed all histological classes, and were associated with mild IF/TA and vascular damages. The median follow-up was 59.5 [IQR 32.5–99.0] months; at follow-up, 40% of cases did not change histologic classification, two patients with class IIb downgraded to IIa or I and one with class III downgraded to IIb. Conversely, three cases showed a worsening, from class 0 to I, I to IIb or from IIa to IIb. We also observed a moderate evolution of IF/TA and vascular damages. At follow-up visit, estimated GFR was stable (50.7 mL/min vs. 54.8 at baseline) and proteinuria was mild (51.1 ± 78.6 mg/day). Conclusions Kidneys from diabetic donors show variable evolution of the histologic features of diabetic nephropathy after transplant. This variability may be associated to recipients characteristics such as euglycemic milieu, in case of improvement, or obesity and hypertension, in case of worsening of histologic lesions.

Crohn’s disease (CD) and ulcerative colitis are chronic and idiopathic inflammatory bowel diseases, characterized by gastrointestinal symptoms such as abdominal pain, fecal urgency, and diarrhea1,2; and extra intestinal manifestations that may involve almost any organ including the kidney. The most common renal extra intestinal manifestations are nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis, and amyloidosis. In addition, kidney damage in patients with CD may result from dehydration, long-term malnutrition, anemia, and side-effects of medical therapy.

For a long time, ABO incompatible living donor kidney transplantation has been considered contraindicated, due to the presence of isohemagglutinins, natural antibodies reacting with non-self ABO antigens. However, as the demand for kidney transplantation is constantly growing, methods to expand the donor pool have become increasingly important. Thus, in the last decades, specific desensitization strategies for ABOi transplantation have been developed. Nowadays, these regimens consist of transient removal of preformed anti-A or anti-B antibodies by using plasmapheresis or immunoadsorption and B-cell immunity modulation by CD20+ cells depletion with rituximab, in association with maintenance immunosuppression including corticosteroids, tacrolimus and mycophenolate mofetil. The outcome in ABOi kidney transplantation have markedly improved over the years. In fact, although randomized trials are still lacking, recent meta analysis has revealed that there is no difference in terms of graft and patient???s survival between ABOi and ABO compatible kidney transplant, even in the long term. However, many concerns still exist, because ABOi kidney transplantation is associated with an increased risk of bleeding and infectious complications, partly related to the effects of extracorporeal treatments and the strong immunosuppression. Thus, a continuous improvement in desensitization strategies, with the aim of minimize the immunosuppressive burden, on the basis of immune pathogenesis, antibodies titers and/or ABO blood group, is warranted. In this review, we discuss the main immune mechanisms involved in ABOi kidney transplantation, the pathogenesis of tolerance and the desensitization regimens, including immunoadsorption and plasmapheresis and the immunosuppressive protocol. Finally, we provide an overview on outcome and future perspectives in ABOi kidney transplant.

Chronic kidney disease (CKD) is a complex and multifactorial disease, and one of the most prevalent worldwide. Chronic kidney disease–mineral bone disorders (CKD–MBD) with biochemical and hormonal alterations are part of the complications associated with the progression of CKD. Pathophysiology of CKD–MBD focused on abnormalities in serum levels of several biomarkers (such as FGF-23, klotho, phosphate, calcium, vitamin D, and PTH) which are discussed in this review. We therefore examine the prognostic association between CKD–MBD and the increased risk for cardiovascular events, mortality, and CKD progression to end-stage kidney disease (ESKD). Lastly, we present specific treatments acting on CKD to prevent and treat the complications associated with secondary hyperparathyroidism (SHPT): control of hyperphosphatemia (with dietary restriction, intestinal phosphate binders, and adequate dialysis), the use of calcimimetic agents, vitamin D, and analogues, and the use of bisphosphonates or denosumab in patients with osteoporosis.

Systemic sclerosis (SSc) is an immune-mediated rheumatic disease characterized by vascular abnormalities, tissue fibrosis, and inflammation. Renal disease occurring in patients with SSc may have a variable clinicopathological picture. However, the most specific renal condition associated with this disease is the scleroderma renal crisis (SRC), characterized by acute onset of renal failure and severe hypertension. SRC develops in about 20% of cases of SSc, especially in those patients with diffuse cutaneous disease. The prognosis of this condition is often negative, with a rapid progression to end-stage renal disease (ESRD). The advent of the antihypertensive angiotensin-converting enzyme inhibitors in 1980 was associated with a significant improvement in patients’ survival and recovery of renal function. However, the prognosis of these patients can still be improved. The dialytic condition is associated with early death, and mortality is significantly higher than among patients undergoing renal replacement therapy (RRT) due to other conditions. Patients with SRC who show no signs of renal functional recovery despite timely blood pressure control are candidates for kidney transplantation (KT). In this review, we reported the most recent advances in KT in patients with ESRD due to SSc, with a particular overview of the risk of disease recurrence after transplantation and the evolution of other disease manifestations.

Although most patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) experience respiratory manifestations, multi-organ dysfunction is frequent. Almost 20% of hospitalized patients with SARS-CoV-2 infection develop acute kidney injury (AKI). The pathophysiology of AKI is a result of both the direct and indirect effects of SARS-CoV-2 infection, including systemic inflammatory responses, the activation of the renin-angiotensin-aldosterone system (RAAS), and endothelial and coagulative dysfunction. Underlying SARS-CoV-2 infection-associated AKI, an immunological hyper-response with an unbalanced innate and adaptative response defined as a "cytokine storm" has emerged. Numerous agents have been tested in an effort to mitigate the cytokine storm, and a range of extracorporeal cytokine removal techniques have been proposed as potential therapeutic options. In the present review, we summarize the main pathogenetic mechanisms underlying COVID-19-related AKI in order to provide an appropriate individual therapeutic strategy to improve clinical outcomes and limit the progression of early disease.

Diabetes is the leading cause of kidney failure and specifically, diabetic kidney disease (DKD) occurs in up to 30% of all diabetic patients. Kidney disease attributed to diabetes is a major contributor to the global burden of the disease in terms of clinical and socio-economic impact, not only because of the risk of progression to End-Stage Kidney Disease (ESKD), but also because of the associated increase in cardiovascular (CV) risk. Despite the introduction of novel treatments that allow us to reduce the risk of future outcomes, a striking residual cardiorenal risk has been reported. This risk is explained by both the heterogeneity of DKD and the individual variability in response to nephroprotective treatments. Strategies that have been proposed to improve DKD patient care are to develop novel biomarkers that classify with greater accuracy patients with respect to their future risk (prognostic) and biomarkers that are able to predict the response to nephroprotective treatment (predictive). In this review, we summarize the principal prognostic biomarkers of type 1 and type 2 diabetes and the novel markers that help clinicians to individualize treatments and the basis of the characteristics that predict an optimal response.