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Few trials have investigated late preemptive conversion of kidney transplant patients from a calcineurin inhibitor (CNI) to an mTOR inhibitor. In an open-label, 12-month, prospective, randomized, parallel-group study, maintenance kidney transplant patients (>6 months post-transplant) either switched from CNI to everolimus or continued their current CNI regimen. Patients who completed the core study were followed to 5 years post-randomization. Of 93 randomized patients, 78 completed the core study and 67 attended the final 60-month study visit. Mean time post-transplant at baseline was 82.6 months and 70.5 months in the everolimus and CNI groups, respectively. At month 60, adjusted mean eGFR (Nankivell) was 63.0 (95 % CI 57.8, 68.2) mL/min/1.73 m2 in the everolimus group versus 57.9 (95 % CI 52.6, 63.1) mL/min/1.73 m2 in the CNI group, a difference of 5.1 (95 % CI −0.6, 10.8) mL/min/1.73 m2 (p = 0.076). Among patients who remained on randomized study drug at month 60, mean eGFR (Nankivell) was 71.6 (95 % CI 64.2, 79.0) mL/min/1.73 m2 in everolimus-treated patients (n = 21) versus 60.6 (95 % CI 55.1, 66.1) mL/min/1.73 m2 in CNI-treated patients (n = 29) (mean difference 11.0; 95 % CI 3.6, 18.5 mL/min/1.73 m2; p = 0.005). No cases of BPAR occurred from randomization to month 60 in either group. Graft loss occurred in three everolimus-treated patients and one CNI-treated patient. No unexpected safety concerns were observed in either group. Late preemptive conversion of maintenance kidney transplant patients from CNI to everolimus may be associated with improved long-term renal function and preserves immunosuppressive efficacy. Patient numbers were low, but these findings merit further investigation.

TAFRO syndrome is characterized by the presence of thrombocytopenia, anasarca, fever, reticular myelofibrosis, organomegaly, and is frequently associated with kidney damage in the form of membranoproliferative glomerulonephritis (MPGN) or thrombotic microangiopathy (TMA). Treatment is based on corticosteroids. A 59-year-old man who suffered from heart disease, pancytopenia and hepatosplenomegaly of unknown etiology developed nephrotic syndrome and progressive renal insufficiency, with a kidney biopsy suggestive of MPGN with a “full-house” immunofluorescence pattern. Positron emission tomography (PET) revealed multiple lymphadenopathies which histologically were compatible with multicentric Castleman's disease. The patient was diagnosed with TAFRO syndrome and treatment with siltuximab was started, with evident improvement at 3 months. TAFRO syndrome is a rare entity which may present with severe kidney involvement and histological findings of MPGN or TMA, with or without immune complex deposits. Our case suggests that a corticosteroid-free regimen with siltuximab could be an attractive therapeutic option.

Renal involvement is a common and severe complication of ANCA (antineutrophil cytoplasmic antibody) associated vasculitis (AAV) potentially resulting in a pauci-immune necrotizing and crescentic antineutrophil cytoplasmic antibody (ANCA) glomerulonephritis (GN) with acute kidney injury (AKI), end-stage renal disease (ESRD) or death. We recently described that Bowman’s capsule rupture links glomerular damage to tubulointerstitial inflammation in ANCA-associated glomerulonephritis. Herein we provide a comprehensive histological subtyping of immune cell infiltrates in association with Bowman’s capsule rupture in ANCA GN. A total of 44 kidney biopsies with ANCA GN were retrospectively included in a single-center observational study. Within a renal biopsy specimen, each glomerulus was scored separately for the presence of extensive and focal Bowman’s capsule rupture in injured glomeruli. Infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the area of total cortical inflammation. Extensive Bowman’s capsule rupture was associated with tubulointerstitial inflammation containing infiltrates of neutrophils, eosinophils and plasma cells. A similar association was observed for the presence of focal Bowman’s capsule rupture, correlating with tubulointerstitial inflammation containing neutrophils, eosinophils and plasma cells. Multiple logistic regression confirmed that extensive Bowman’s capsule rupture correlated with tubulointerstitial inflammation containing neutrophils, and focal Bowman’s capsule rupture correlated with neutrophil and plasma cell infiltration. Furthermore, this association was specifically observed in PR3-ANCA GN. To our knowledge, this is the first report linking Bowman’s capsule rupture directly to tubulointerstitial inflammation by immune cell subtypes. This underscores a pathomechanistic link between tubulointerstitial and glomerular lesions in ANCA GN and needs further investigation.

Kidney disease in diabetes mellitus is usually explained by diabetic kidney disease, but other superimposed etiologies occur frequently. The distinction between diabetic kidney disease and non-diabetic kidney disease can only be made by performing kidney biopsy. Our objective was to evaluate the association of diabetic kidney disease, non-diabetic kidney disease, or both with renal replacement therapy initiation. This is a retrospective cohort that included patients with type 2 diabetes mellitus for whom a kidney biopsy was indicated. Subjects were followed-up for 5 years, until renal replacement therapy initiation or were lost to follow up. One hundred and forty-one patients were included, 53 (39%) had diabetic kidney disease, 13 (9%) had non-diabetic kidney disease and 75 (54%) had both. Ninety-four percent of the cohort initiated renal replacement therapy during the 5-year follow-up. Higher degree of fibrosis was associated with a trend towards higher risk of requiring renal replacement therapy. In addition, the combined diabetic kidney disease + non-diabetic kidney disease group was associated with higher need of renal replacement therapy initiation when compared to the diabetic kidney disease group.

Kidney transplantation has become the preferred method of renal replacement. However, the rate of long term allograft survival has not changed over the last decade. Donor and recipient genetic interplay influences kidney transplant outcome but our knowledge of these complex interactions is limited. Until recently, investigations have been limited to small candidate gene studies, usually restricted to allograft recipients. Genome-wide association studies have been slow to emerge in transplantation but the first has recently been reported and will be reviewed here. Much larger studies involving donor and recipients pairs are ongoing. We are now entering the era of epigenetics and whole genome sequencing which will hopefully provide a more in-depth knowledge of the genetic influences on renal transplant outcome. This may lead to a more accurate assessment of post-transplant risk, potentially allowing for the development of risk predication models leading to a more personalized approach to kidney transplant care. In this article, we examine the current and emerging literature in the field and discuss the limitations of current studies and technologies.

Vascular calcification in chronic kidney disease (CKD) patients is associated to increased mortality. Osteoprotegerin (OPG) is a soluble tumor necrosis factor (TNF) superfamily receptor that inhibits the actions of the cytokines receptor activator of nuclear factor kappa-B ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL) by preventing their binding to signaling receptors in the cell membrane. OPG-deficient mice display vascular calcification while OPG prevented calcification of cultured vascular smooth muscle cells and protected kidney cells from TRAIL-induced death. OPG may be a biomarker in patients with kidney disease. Circulating OPG is increased in predialysis, dialysis and transplant CKD patients and may predict vascular calcification progression and patient survival. By contrast, circulating OPG is decreased in nephrotic syndrome. In addition, free and exosome-bound urinary OPG is increased in human kidney disease. Increased urinary OPG has been associated with lupus nephritis activity. Despite the association of high OPG levels with disease, experimental functional information available suggests that OPG might be protective in kidney disease and in vascular injury in the context of uremia. Thus, tissue injury results in increased OPG, while OPG may protect from tissue injury. Recombinant OPG was safe in phase I randomized controlled trials. Further research is needed to fully define the therapeutic and biomarker potential of OPG in patients with kidney disease.

Vitamin D deficiency is associated with increased risks of mortality in people with chronic kidney disease. The benefits and harm of vitamin D supplementation on cardiovascular outcomes and mortality are unknown. We aimed to assess the effectiveness of calcifediol in reducing mortality in patients with vitamin D insufficiency on hemodialysis compared to no additional therapy. A phase III, multicenter, randomized, open-label trial was conducted including 284 adults with vitamin D insufficiency undergoing hemodialysis who were randomly assigned to receive oral calcifediol or standard care for 24 months. Two hundred eighty-four participants were enrolled (143 assigned to the calcifediol group and 141 to the no additional therapy group). The primary outcome (mortality) occurred in 34 and 31 participants in the calcifediol and control group, respectively [hazard ratio (HR) 1.03; 95% confidence interval (CI) 0.63–1.67]. Calcifediol had no detectable effects on cardiovascular death (HR 1.06; 95% CI 0.41–2.74), non-cardiovascular death (HR 1.13; 95% CI 0.62–2.04), nonfatal myocardial infarction (HR 0.20; 95% CI 0.02–1.67) or nonfatal stroke (HR could not be estimated). The incidence of hypercalcemia and hyperphosphatemia was similar between groups. None of the participants underwent parathyroidectomy. In adults treated with hemodialysis and who had vitamin D insufficiency, calcifediol supplementation for 24 months had inconclusive effects on mortality and cardiovascular outcomes. NCT01457001