Plasma proteomics of diabetic kidney disease among Asians with younger-onset type 2 diabetes.

CONTEXT: Patients with younger onset of type 2 diabetes (YT2D) have increased risk for kidney failure compared to those with late onset. However, the mechanism of diabetic kidney disease (DKD) progression in this high-risk group is poorly understood. OBJECTIVES: To identify novel biomarkers and potential causal proteins associated with DKD progression in patients with YT2D. DESIGN AND PARTICIPANTS: Among YT2D (T2D onset age ≤ 40 years), 144 DKD progressors (cases) were matched for T2D onset age, sex, and ethnicity with 292 non-progressors (controls) and divided into discovery and validation sets. DKD progression was defined as decline of estimated glomerular filtration rate (eGFR) of 3ml/min/1.73m2 or greater or 40% decline in eGFR from baseline. 1472 plasma proteins were measured through a multiplex immunoassay that uses a proximity extension assay technology. Multivariable logistic regression was used to identify proteins associated with DKD progression. Mendelian randomization (MR) was used to evaluate causal relationship between plasma proteins and DKD progression. RESULTS: 42 plasma proteins were associated with DKD progression, independent of traditional cardio-renal risk factors, baseline eGFR and urine albumin-to-creatinine ratio (uACR). The proteins identified were related to inflammatory and remodelling biological processes. Our findings suggested angiogenin as one of the top signals (odds ratio =5.29, 95% CI 2.39-11.73, P = 4.03 × 10-5). Furthermore, genetically determined plasma angiogenin level was associated with increased odds of DKD progression. CONCLUSION: Large-scale proteomic analysis identified novel proteomic biomarkers for DKD progression in YT2D. Genetic evidence suggest a causal role of plasma angiogenin in DKD progression.

Oral Peroxisome Proliferator-Activated Receptor-α Agonist Enhances Corneal Nerve Regeneration in Patients With Type 2 Diabetes.

Diabetic corneal neuropathy (DCN) is a common complication of diabetes. However, there are very limited therapeutic options. We investigated the effects of a peroxisome proliferator-activated receptor-α (PPAR-α) agonist, fenofibrate, on 30 patients (60 eyes) with type 2 diabetes. On in vivo confocal microscopy evaluation, there was significant stimulation of corneal nerve regeneration and a reduction in nerve edema after 30 days of oral fenofibrate treatment, as evidenced by significant improvement in corneal nerve fiber density (CNFD) and corneal nerve fiber width, respectively. Corneal epithelial cell morphology also significantly improved in cell circularity. Upon clinical examination, fenofibrate significantly improved patients' neuropathic ocular surface status by increasing tear breakup time along with a reduction of corneal and conjunctival punctate keratopathy. Tear substance P (SP) concentrations significantly increased after treatment, suggesting an amelioration of ocular surface neuroinflammation. The changes in tear SP concentrations was also significantly associated with improvement in CNFD. Quantitative proteomic analysis demonstrated that fenofibrate significantly upregulated and modulated the neurotrophin signaling pathway and linolenic acid, cholesterol, and fat metabolism. Complement cascades, neutrophil reactions, and platelet activation were also significantly suppressed. Our results showed that fenofibrate could potentially be a novel treatment for patients with DCN.

Red Meat Intake and Risk of ESRD.

Randomized controlled trials suggest that protein restriction may retard the progression of CKD toward ESRD. However, the effects of dietary protein intake level and the food sources of dietary protein on the risk of ESRD in the general population remain unclear. We investigated these effects in the Singapore Chinese Health Study, a prospective population-based cohort that recruited 63,257 Chinese adults aged 45-74 years from 1993 to 1998. We collected habitual diet information via a validated semiquantitative food frequency questionnaire and identified ESRD via record linkage with a nationwide registry. In all, 951 cases of ESRD occurred over a mean follow-up of 15.5 years. Regarding total protein intake, compared with the lowest quartile, the three higher quartiles combined had a hazard ratio for ESRD of 1.24 (95% confidence interval [95% CI], 1.05 to 1.46), but the dose-dependent association across the quartiles was not statistically significant (Ptrend=0.16). Red meat intake strongly associated with ESRD risk in a dose-dependent manner (hazard ratio for highest quartile versus lowest quartile,1.40 [95% CI, 1.15 to 1.71; Ptrend<0.001]). Intake of poultry, fish, eggs, or dairy products did not associate with risk of ESRD. In substitution analysis, replacing one serving of red meat with other food sources of protein associated with a maximum relative risk reduction of 62.4% (95% CI, 33.1 to 78.9; P<0.01). Our study shows that red meat intake may increase the risk of ESRD in the general population and substituting alternative sources of protein may reduce the incidence of ESRD.