Nephrology Dialysis Transplantation最新文献

Background and hypothesis: Proteinuria exhibits seasonal fluctuations, decreasing in summer and increasing in winter. It is unknown whether the association between proteinuria and the risk of kidney failure varies by season.

Methods: The Osaka Consortium for Kidney Disease Research (OCKR) database contained retrospective data from 15 367 patients with estimated glomerular filtration rates of 10-60 mL/min/1.73m2, who were referred to the Department of Nephrology at five clinical centers in Japan, between 2010 and 2021. Multivariate Cox models were used to examine the associations of urinary protein-to-creatinine ratio (UPCR) in summer (UPCRsummer) and winter (UPCRwinter) with kidney failure defined as initiation of kidney replacement therapy. LASSO was used to compare the strength of the association between UPCRsummer and UPCRwinter with respect to kidney failure. We also assessed whether seasonal fluctuations in UPCR were associated with kidney failure.

Results: The median [interquartile range] UPCRwinter was 0.89 [0.22, 2.69] g/gCre, 46% higher than UPCRsummer (0.61 [0.16, 1.87] g/gCre). During a median follow-up of 3.0 years, 1 585 patients developed kidney failure. In time-dependent Cox models, UPCRwinter showed a higher hazard of kidney failure (1.66 per 1-standard deviation [SD] increase; 95% confidence interval [CI], 1.60-1.73) than UPCRsummer (1.45 per 1-SD increase; 95%CI, 1.41-1.48). LASSO identified that UPCRwinter was more strongly associated with kidney failure than UPCRsummer. Furthermore, higher % changes in UPCRwinter relative to UPCRsummer was associated with a higher hazard of kidney failure.

Conclusions: Proteinuria in winter exhibited stronger associations with kidney failure than that in summer. Seasonal fluctuations in UPCR should not be overlooked in the management of CKD to make reasonable clinical decisions.

Background and hypothesis: Increased T cell IL-7Rα signaling is associated with a poorer prognosis in ANCA-associated vasculitis. These studies examined the functional role of IL-7Rα (CD127) in experimental glomerulonephritis mediated by anti-MPO T cell autoimmunity. We hypothesized that T cells would express IL-7Rα in the kidney and that blocking the function of IL-7Rα, without cellular depletion, would be protective.

Methods: Mice were immunised with mouse MPO, then low-dose sheep anti-mouse basement membrane (BM) globulin was administered to trigger glomerulonephritis. Flow cytometry and RNA-sequencing characterised intrarenal CD127+ expressing CD4+ and CD8+ T cells in mice with anti-MPO glomerulonephritis. To assess the functional role of IL-7Rα, mice with established anti-MPO autoimmunity were treated with anti-IL-7Rα antibodies.

Results: Control ovalbumin-immunized mice given anti-BM globulin developed minimal injury, while MPO-immunised mice given anti-BM globulin developed albuminuria with glomerular and tubulointerstitial injury. Numbers of intrarenal IL-7Rα+ (CD127+) CD4+ and CD8+ T cells were increased in mice with anti-MPO glomerulonephritis. There were 3 738 and 2 726 genes differentially expressed between intrarenal CD127¯PD-1+ and CD127+PD-1¯ CD8+ and CD4+ T cells, respectively, with substantially overlapping differentially expressed genes between CD8+ and CD4+ T cells. Both CD127¯PD-1+ CD8+ and CD4+ T cells were enriched for previously described T cell exhaustion signatures associated with prognosis in autoimmune disease. As effector memory T cells drive inflammation, we blocked the IL-7Rα after inducing anti-MPO autoimmunity. Anti-IL-7Rα antibodies limited histological injury, and reduced albuminuria numbers of glomerular and interstitial leukocytes, with reduced intrarenal chemokine and pro-inflammatory cytokine expression.

Conclusions: Intrarenal effector memory and exhausted CD4+ and CD8+ T cells are present in experimental anti-MPO glomerulonephritis. Neutralising effector T cells via the IL-7Rα after the induction of autoimmunity limits intrarenal inflammation and disease. IL-7Rα may be a therapeutic target in ANCA-associated vasculitis.

Background and hypothesis: Measurement of glomerular filtration rate (GFR) is subject to inaccurate urine collection. Clearances of d-serine and d-asparagine, rare enantiomers of amino acids, are the measures of GFR since they are almost free of tubular secretion and reabsorption. We hypothesize that d-serine and d-asparagine can accurately determine urine volume and GFR.

Methods: This cross-sectional observational study included 209 living kidney transplant donors and recipients for whom GFR was measured using the clearance of inulin. Assuming that urine excretions of d-serine and d-asparagine are constant and using urine levels of d-serine and d-asparagine from each urine collection, an equation for estimated urine volume (eUV) was established. Based on the eUV, the abnormal urine volume was replaced with an estimate with which the GFR was re-evaluated.

Result: Clearances of d-serine and d-asparagine were minor in proportional biases when compared with that of creatinine. Using 627 urine collection, the equation for eUV (mL/min) was established as 21.88/urine d-Ser (0.40 + 0.20 × log10(urine d-Asn)). Using eUV, we identified 20 instances where urine collection volumes varied significantly from the estimated values. After replacement with eUV, measured GFR (mGFR) was corrected to adjusted mGFR, which was within approximately 20 mL/min/1.73m2 of the mGFR.

Conclusion: d-Serine and d-asparagine are nearly completely excreted in urine after glomerular filtration, enabling the estimation of urine volume and correct mGFR. Besides reflecting GFR, d-serine and d-asparagine can be used to estimate urine volume. By applying the eUV method, mGFR determined using clearance methods becomes more accurate.

In the current paper, we will focus on requirements to ensure big data can advance the outcomes of our patients suffering from kidney disease. The associated ethical question is whether and how we as a nephrology community can and should encourage the collection of big data of our patients. We identify some ethical reflections on the use of big data, and their importance and relevance. Furthermore, we balance advantages and pitfalls and discuss requirements to make legitimate and ethical use of big data possible. The collection, organization and curation of data come upfront in the pipeline prior to any analyses. Great care must therefore be taken to ensure quality of the data at this stage, to avoid the garbage in garbage out problem and suboptimal patient care as a consequence of such analyses. Access to the data should be organized so that correct and efficient use of data is possible. This means that data must be stored safely, so that only those entitled to do so can access them. At the same time, those who are entitled to access the data should be able to do so in an efficient way, so as not to hinder relevant research. Analysis of observational data is itself prone to many errors and biases. Each of these biases can finally result in provision of low-quality medical care. Secure platforms should therefore also ensure correct methodology is used to interpret the available data. This requires close collaboration of a skilled workforce of experts in medical research and data scientists. Only then will our patients be able to benefit fully from the potential of AI and big data.

Background and hypothesis: It is presently unclear why there is a high prevalence of periodontal disease in individuals living with chronic kidney disease (CKD). Whilst some have argued that periodontal disease causes CKD, we hypothesised that alterations in saliva and the oral microenvironment in organisms with kidney disease may initiate periodontal disease by causing dysbiosis of the oral microbiota.

Methods: Experimental kidney disease was created using adenine feeding and subtotal nephrectomy in rats, and by adenine feeding in mice. Loss of periodontal bone height was assessed using a dissecting microscope supported by micro-CT, light, confocal and electron microscopy, and immunohistochemistry. Salivary biochemistry was assessed using NMR spectroscopy. The oral microbiome was evaluated using culture-based and molecular methods, and the transmissibility of dysbiosis was assessed using co-caging and microbial transfer experiments into previously germ-free recipient mice.

Results: We demonstrate that experimental kidney disease causes a reproducible reduction of alveolar bone height, without gingival inflammation or overt hyperparathyroidism but with evidence of failure of bone formation at the periodontal crest. We show that kidney disease alters the biochemical composition of saliva and induces progressive dysbiosis of the oral microbiota, with microbial samples from animals with kidney disease displaying reduced overall bacterial growth, increased alpha diversity, reduced abundance of key components of the healthy oral microbiota such as Streptococcus and Rothia, and an increase in minor taxa including those from gram-negative phyla Proteobacteria and Bacteroidetes. Co-housing diseased rats with healthy ones ameliorates the periodontal disease phenotype, whilst transfer of oral microbiota from mice with kidney disease causes periodontal disease in germ-free animals with normal kidney function.

Conclusions: We advocate that periodontal disease should be regarded as a complication of kidney disease, initiated by oral dysbiosis through mechanisms independent of overt inflammation or hyperparathyroidism.

Background and hypothesis: Hepatitis C virus (HCV) positive-to-negative kidney transplants (KT) require direct acting antiviral therapy, but the optimal timing and duration remain unclear. We hypothesized that 14-day prophylactic course of glecaprevir/pibrentasvir 300/120 mg (GLE/PIB) would be safe and effective at treating donor-derived HCV viremia.

Methods: This was a prospective, single-center, single-arm, open-label pilot study. 20 adult HCV negative recipients of HCV nucleic acid amplification test positive deceased-donor kidneys (HCV positive-to-negative) received a 14-day course of GLE/PIB, with the first dose pre-transplant. HCV RNA viral loads (VL) were monitored on post-operative days (POD) 1, 3, 7, and 13. If VL was undetectable on POD 13, GLE/PIB was stopped, and if detectable, GLE/PIB was continued to complete an 8-week course. Surveillance monitoring continued after treatment to ensure sustained viral response (SVR). The primary outcome was efficacy of 14-day prophylactic GLE/PIB. Secondary outcomes included patient and allograft survival, the incidence, timing, and clearance of HCV viremia, and safety events.

Results: 7/20 subjects (35%) never developed detectable HCV viremia. Only one subject had a detectable, but nonquantifiable, VL on POD 13 and completed an 8-week course. All subjects achieved SVR 12 weeks post-treatment with no relapses through 1-year follow-up. Mean time to undetectable HCV RNA VL was 10.5 (±4.7) days and mean peak VL was 371 (±715) copies/mL. 6-month and 1-year patient and allograft survival were 100% and 95%.

Conclusion: A 14-day course of prophylactic GLE/PIB is safe and effective for HCV positive-to-negative KT and may prevent HCV transmission or significantly reduce the VL for those with detectable transmission allowing for rapid clearance within 2 weeks.

Background and hypothesis: In patients with advanced chronic kidney disease (CKD), the lifespan of red blood cells (RBC) is often shortened, a condition attributed to the "uremic milieu." We reported recently that the uremic solute 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF) shares structural similarities with Jedi1, a chemical activator of the mechanosensitive cation channel Piezo1, whose activation increases calcium influx into cells. Against this backdrop, we hypothesized that CMPF may induce premature RBC death (eryptosis) through prolonged CMPF-induced activation of Piezo1 located on RBC. To test this hypothesis, we explored if CMPF, at concentrations found in uremia, interacts with Piezo1 located on RBC, increases intracellular calcium (icCa2+), and induces eryptosis.

Methods: RBC from healthy individuals were incubated with CMPF or Jedi1 (both at a concentration of 87 µM), in the presence or absence of the Piezo1 inhibitor GsMTx-4 (2 µM). We challenged RBC osmotically through incubation in solutions of NaCl at concentrations between 3.0 and 9.0 g/L and determined their osmotic fragility. Using flow cytometry, we quantified in incubated RBC icCa2+ levels and phosphatidylserine exposure, a cellular marker of eryptosis.

Results: Incubation of RBC with CMPF and Jedi1 significantly increased RBC osmotic fragility, an effect prevented by GsMTx-4. At 6.0 g/L NaCl, incubation with CMPF and Jedi1 increased exposure of phosphatidylserine and elevated icCa2+ levels of RBC, indicating increased eryptosis. Notably, at an isotonic NaCl concentration of 9.0 g/L, CMPF - but not Jedi1 - significantly increased RBC phosphatidylserine exposure and icCa2+ levels; both effects were diminished by GsMTx-4.

Conclusion: Our findings support the hypothesis that CMPF may function as an endogenous activator of Piezo1, increase icCa2+ levels, trigger eryptosis, and, through this pathway, possibly shorten the RBC life span. To what extent these in vitro findings are operative in advanced CKD warrants clinical studies.

Background and hypothesis: Activated macrophages, pivotal for driving the immune response in sepsis, express high levels of CD38. Although the circulating levels of its ligand, CD31, increase in sepsis, the functions of CD38 and its ligation remain elusive. This study aimed to elucidate the impact of CD38 ligation on sepsis using single-cell and single-nucleus RNA sequencing (scRNA-seq and snRNA-seq, respectively) to identify a novel therapeutic target for severe sepsis.

Methods: We performed scRNA-seq analysis of mouse peritoneal immune cells to precisely identify cell types exhibiting increased CD38 expression upon exposure to lipopolysaccharide (LPS). Subsequently, we induced CD38 ligation using a well-established agonistic anti-CD38 antibody in a mouse model of LPS-induced sepsis. We analyzed its pathophysiological effects using kidney snRNA-seq. Finally, we performed histological analysis of septic tissues collected from patients to ensure consistency of our findings between mice and humans.

Results: LPS stimulation upregulated CD38 expression in peritoneal macrophages. CD38 ligation significantly exacerbated LPS-induced inflammation in vivo, particularly in the kidneys. Kidney snRNA-seq analysis revealed that CD38 ligation induced interleukin (IL)-6 production in renal stromal cells via nicotinamide phosphoribosyltransferase (NAMPT) signaling originating from CD38-positive macrophages. NAMPT inhibition significantly ameliorated LPS-induced IL-6 production and kidney injury. Histological analysis of human septic tissues demonstrated upregulation of IL6 mRNA and NAMPT in renal stromal cells and CD38-positive macrophages, respectively.

Conclusion: Our findings elucidate the implications of CD38 ligation in an LPS-induced sepsis model and uncover shared signaling pathways between mice and human sepsis. NAMPT signaling identified in this study may be a novel therapeutic target for mitigating systemic inflammation and kidney injury associated with severe sepsis.

Background and hypothesis: The long-term prognosis of IgA nephropathy (IgAN) and the optimal target for proteinuria treatment remain controversial. This study, utilizing a large prospective cohort from China, aims to assess the long-term outcomes of IgAN and to explore the definition of proteinuria remission.

Methods: We enrolled 2 141 patients with biopsy-proven IgAN, all with at least 12 months of follow-up, from a prospective IgAN cohort at Peking University First Hospital. We utilized Kaplan-Meier analysis, Cox regression, and an eGFR slope calculated via a linear mixed model to investigate kidney outcomes.

Results: The median (Q1, Q3) baseline proteinuria was 1.26 (0.65, 2.40) g/d, and the estimated GFR was 80 (52, 103) mL/min/1.73m2. After a mean follow-up of 5.8 (±4.4) years, 509 (24%) patients progressed to end-stage kidney disease (ESKD). The median kidney survival time was 12.4 years, the annual event rate of ESKD was 41.1 per 1000 person-years, and the 15-year kidney survival rate was 40%. Time-averaged proteinuria level was strongly associated with kidney failure (adjusted HR: 1.76, 95%CI: 1.65 to 1.88). Restriction cubic spline analysis indicated that the risk of ESKD increases rapidly when time-average proteinuria exceeded 0.5 g/d. There was no significant difference in long-term kidney survival between patients with proteinuria < 0.3 g/d and those with 0.3-0.5 g/d, with both groups demonstrating a better prognosis.

Conclusion: The long-term outcomes for patients with IgAN under current treatment strategies remain poor, with most progressing to ESKD within 15 years. Patients with time-averaged proteinuria ≥ 0.5 g/d experience worse kidney outcomes, challenging the previous view that proteinuria < 1.0 g/d was associated with a low risk of kidney failure.

Background and hypothesis: Chronic kidney disease (CKD) remains unexplained in at least 20% of patients. Massively parallel sequencing (MPS) can be a valuable diagnostic tool in patients with unexplained CKD, but prospective data from routine clinical practice are limited. We aimed to determine the diagnostic yield and relevance of MPS-based gene panel testing in patients with unexplained CKD in a real-world context. We additionally examined barriers to implementation of genetic testing.

Methods: In this prospective cohort study, we recruited patients with unexplained CKD (eGFR <60mL/min/1.73 m2 without underlying clinical diagnosis) with onset <50 years who underwent MPS-based multi-gene panel testing from 11 academic and non-academic hospitals across the Netherlands. In patients with a (likely) pathogenic variant, we verified that the variant likely explained the clinical phenotype. A nationwide online survey was sent out to all Dutch nephrologists and residents to investigate potential barriers for gene panel testing.

Results: A diagnostic variant was identified in 59/340 participants (17%). Most common diagnostic variants were in NPHP1 (13 patients), COL4A3 (12 patients), COL4A4 (5 patients), COL4A5 (6 patients), and PAX2 (5 patients). A genetic diagnosis led to at least one clinical consequence in 73% of patients. Main barriers reported by Dutch nephrologists (N=71) included genetic illiteracy (53%), difficulties with test selection (51%), and lack of time (43%).

Conclusion: MPS-based multi-gene panel testing yielded a genetic diagnosis in 17% of patients with unexplained CKD. Our findings support the relevance of MPS in the diagnostic workup of adults with unexplained CKD with onset <50 years. Additionally, our results underline the need to improve genetic education among nephrologists to better the implementation of MPS-based diagnostic testing in clinical practice.