Interaction of uromodulin and complement factor H enhances C3b inactivation

Recent studies suggest that uromodulin plays an important role in chronic kidney diseases. It can interact with several complement components, various cytokines and immune system cells. Complement factor H (CFH), as a regulator of the complement alternative pathway, is also associated with various renal diseases. Thus, we have been suggested that uromodulin regulates complement activation by interacting with CFH during tubulointerstitial injury. We detected co‐localization of uromodulin and CFH in the renal tubules by using immunofluorescence. Next, we confirmed the binding of uromodulin with CFH in vitro and found that the affinity constant (K_D) of uromodulin binding to CFH was 4.07 × 10^?6M based on surface plasmon resonance results. The binding sites on CFH were defined as the short consensus repeat (SCR) units SCR1–4, SCR7 and SCR19–20. The uromodulin‐CFH interaction enhanced the cofactor activity of CFH for factor I‐mediated cleavage of C3b to iC3b. These results indicate that uromodulin plays a role via binding and enhancing the function of CFH.     

血清半胱氨酸蛋白酶抑制剂C在肾移植患者肾功能监测中的临床应用

目的针对肾移植术后稳定期患者,进行血清半胱氨酸蛋白酶抑制剂C(Cystatin C)和血清肌酐(SCr)的灵敏度的比较。方法在HITACHI-7600-020型自动生化分析仪上采用微粒子颗粒增强透射免疫比浊分析法等方法测定肾移植术后稳定期患者的Cystatin C、SCr等指标。结果对数据用SPSS 11.5软件包进行χ2检验,P<0.01,故可以认为2种检测指标间的差异有统计学意义,即Cystatin C与SCr相比有较好的敏感度。结论血清Cystatin C在稳定期肾移植患者中敏感性与SCr差异存在统计学意义,且优于SCr,能更敏感,更及时的反映GFR的变化,可作为稳定期肾移植患者判断急、慢性排斥和免疫抑制剂的毒性的最重要的观察指标之一。     

Delayed graft function and chronic allograft nephropathy: diagnostic and prognostic role of neutrophil gelatinase-associated lipocalin

Context: Available markers are not reliable parameters to early detect kidney injury in transplanted patients.

Objective: Examine neutrophil gelatinase associated lipocalin (NGAL) in early detection of delayed graft function (DGF) and as a long-term predictor of graft outcome.

Patients and methods: NGAL was evaluated in 124 transplanted patients.

Results: Urinary NGAL levels were associated to a 10% (HR: 1.10; 95% CI: 1.04–1.25; p?<?0.001) and 15% (HR: 1.15; 95% CI: 1.09–1.26; p?<?0.001) increased risk of DGF and allograft nephropathy progression, respectively.

Conclusion: NGAL reflects the entity of renal impairment in transplanted patients, representing a biomarker and an independent risk factor for DGF and chronic allograft nephropathy progression.     

1982至2020年中国肾移植受者合并隐球菌病的系统分析

隐球菌病是威胁肾移植患者生命的严重感染性疾病,本文旨在报道我国肾移植患者合并隐球菌病(cryptococcosis in kidney transplant patients,C-KT)的情况.通过对208例患者的资料进行分析,发现隐球菌病平均发病时间为肾移植后(5.48±4.09)年,就诊时间为发病后(27.28±3...     

Notch3 expression in capillary pericytes predicts worse graft outcome in human renal grafts with antibody‐mediated rejection

Microvasculature consisting of endothelial cells and pericytes is the main site of injury during antibody‐mediated rejection (ABMR) of renal grafts. Little is known about the mechanisms of activation of pericytes in this pathology. We have found recently that activation of Notch3, a mediator of vascular smooth muscle cell proliferation and dedifferentiation, promotes renal inflammation and fibrosis and aggravates progression of renal disease. Therefore, we studied the pericyte expression of Notch3 in 49 non‐selected renal graft biopsies (32 for clinical cause, 17 for graft surveillance). We analysed its relationship with patients’ clinical and morphological data, and compared with the expression of partial endothelial mesenchymal transition (pEndMT) markers, known to reflect endothelial activation during ABMR. Notch3 was de novo expressed in pericytes of grafts with ABMR, and was significantly correlated with the microcirculation inflammation scores of peritubular capillaritis and glomerulitis and with the expression of pEndMT markers. Notch3 expression was also associated with graft dysfunction and proteinuria at the time of biopsy and in the long term. Multivariate analysis confirmed pericyte expression of Notch3 as an independent risk factor predicting graft loss. These data suggest that Notch3 is activated in the pericytes of renal grafts with ABMR and is associated with poor graft outcome.     

N-acetylcysteine decreases urinary level of neutrophil gelatinase-associated lipocalin in deceased-donor renal transplant recipients: a randomized clinical trial

Context: Acute kidney injury (AKI) is a common complication after kidney transplantation (KT), especially in recipients from deceased donors. Urinary neutrophil gelatinase-associated lipocalin (u-NGAL) is an early and sensitive marker of AKI after transplantation.

Objectives: We assessed the renoprotective effect of N-acetylcysteine (NAC) on u-NGAL levels as an early prognostic marker of graft function immediately after transplantation.

Materials and methods: A double-blind, randomized, placebo-controlled trial was conducted on 70 deceased-donor KT recipients (www.irct.ir, trial registration number: IRCT2014090214693N4). Patients received 600?mg oral NAC or placebo twice daily from day 0 to 5 and urine samples were taken before, and on the first and fifth days after transplantation. U-NGAL and early graft function were compared between the two groups.

Results: NAC significantly reduced u-NGAL levels compared to placebo (p value?=?0.02), while improvement in early graft function with NAC did not reach statistical significance.

Conclusions: This study showed that NAC administration in deceased-donor KT recipients can reduce tubular kidney injury, evidenced by u-NGAL measurements. Improvement in early graft function needs a larger sample size to reach a statistical conclusion.     

Novel UMOD mutations in familial juvenile hyperuricemic nephropathy lead to abnormal uromodulin intracellular trafficking

Background

Familial juvenile hyperuricemic nephropathy (FJHN) is an autosomal dominant disorder characterized by hyperuricemia and progressive chronic kidney disease. Uromodulin gene (UMOD) mutations, leading to abnormalities of uromodulin intracellular trafficking contribute to the progress of the disease.

Methods

We did UMOD screening in three Chinese FJHN families. We thus constructed mutant uromodulin express plasmids by site-mutagenesis from wild type uromodulin vector and transfected them into HEK293 (human embryonic kidney) cells. And then we detected uromodulin expression by western blot and observed intracellular distribution by immunofluorescence.

Results

We found three heterozygous mutations. Mutation Val109Glu (c.326T/A; p.Val109Glu) and mutation Pro236Gln (c.707C/A; p.Pro236Gln) were newly indentified mutations in two distinct families (family F1 and family F3). Another previously reported UMOD mutation Cys248Trp (c.744C/G; p.Cys248Trp) was detected in family F2. Phenotypes varied both within the same family and between different families. Uromodulin expression is abnormal in the patient biopsy. Functional analysis of mutation showed that mutant types of uromodulin were secreted into the supernatant medium much less when compared with wild type. In mutant type uromodulin transfected cells, intracellular uromodulin localized less in the Golgi apparatus and more in endoplasmic reticulum(ER).

Conclusions

Our results suggested that the novel uromodulin mutations found in the Chinese families lead to misfolded protein, which was retained in the endoplasmic reticulum, finally contributed to the phenotype of FJHN.