High levels of circulating TNFR1 increase the risk of all-cause mortality and progression of renal disease in type 2 diabetic nephropathy.

BACKGROUND: Several studies have demonstrated that levels of circulating inflammatory markers such as tumour necrosis factorα (TNFα), are associated with early progression of diabetic nephropathy (DN). The aim of this study was to investigate whether there is an association between circulating TNFα receptor and disease progression in patients with advanced type 2 DN and severe proteinuria. METHODS: Between 2006 and 2011, we measured levels of circulating soluble TNFα receptor 1 (TNFR1) and soluble TNFα receptor 2 (TNFR2) at baseline and 4 and 12 months in 101 patients included in a multicenter randomized controlled trial to compare the effect of optimal doses of renin-angiotensin system blockers in monotherapy or in combination (dual blockade) to slow progression of established type 2 DN. The primary composite endpoint was a >50% increase in baseline serum creatinine, end-stage renal disease, or death. RESULTS: The median follow-up was 32 months (IQR, 18-48), during which time 28 patients (22.7%) achieved the primary endpoint. The TNFR1 level, but not the TNFR2 level, was correlated with other inflammatory markers. Cox regression analysis showed that the highest TNFR1 levels (HR, 2.60; 95%CI, 1.11-86.34) and baseline proteinuria (HR 1.32; 95%CI 1.15-1.52) were associated with the primary endpoint. The mixed model analysis revealed that TNFR1 and the TNFR2 levels did not change after starting treatment with renin-angiotensin system blockers. CONCLUSIONS: Our results show that the highest levels of TNFR1 are independently associated with progression of renal disease and death in type 2 DN. The renin angiotensin blockers have no effect on these inflammatory markers.

A novel pattern of mutation in uromodulin disorders: autosomal dominant medullary cystic kidney disease type 2, familial juvenile hyperuricemic nephropathy, and autosomal dominant glomerulocystic kidney disease.

BACKGROUND: Autosomal dominant medullary cystic kidney disease type 2 (MCKD2), familial juvenile hyperuricemic nephropathy (FJHN), and autosomal dominant glomerulocystic kidney disease (GCKD) constitute a hereditary renal disease group that may lead to end-stage renal failure caused by mutations of the UMOD gene and its product, uromodulin or Tamm-Horsfall protein. Of 34 different UMOD mutations described to date, 28 were located in exon 4. Based on such mutation clustering, some investigators have proposed that the sequencing of UMOD exon 4 might become a preliminary diagnostic test for patients with this phenotype. METHODS: We performed linkage analysis and sequencing of the entire codifying region of the UMOD gene in 4 Spanish families with MCKD/FJHN/GCKD. RESULTS: All families were shown to present mutations in the UMOD gene. In 3 families, the detected mutations were located in exon 5. Although 1 novel mutation (Gln316Pro) was observed in 2 of these families, a previously reported mutation (Cys300Gly) was found in the other kindred. The Cys300Gly mutation was found in the family presenting with a GCKD phenotype. CONCLUSION: Our data show a novel mutation pattern in UMOD , suggesting that exon 5 mutations can be more frequent in some populations. Our results support that every exon of the UMOD gene must be included in molecular testing and provide additional evidence for the existence of a fourth calcium-binding epidermal growth factor-like domain in the structure of Tamm-Horsfall protein. A second family reported to date is described, confirming that the GCKD phenotype may be caused by a UMOD mutation.