Serum Albumin Modifies the Effect of Peripheral Blood Monocytes on Severity of Diabetic Nephropathy in an Adult Population

Low Levels of Metrnl are Linked to the Deterioration of Diabetic Kidney Disease

Objective

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. Metrnl is a secreted protein that plays an important role in kidney disease. The aim of this study was to investigate DKD-related factors and the correlation between serum Metrnl levels and the severity of DKD.

Methods

Ninety-six type 2 diabetes mellitus (T2DM) patients and 45 DKD patients were included in the study. A range of parameters were measured simultaneously, including waist-to-hip ratio (WHR), body mass index (BMI), urinary albumin/creatinine ratio (UACR), monocyte-lymphocyte ratio (MLR), albumin/globulin (A/G), liver and kidney function, blood lipid profile, islet function, and others. Subsequently, the related factors and predictive significance of DKD were identified. The correlation between the relevant factors of DKD and serum Metrnl levels with DKD was evaluated.

Results

The duration of the disease (OR: 1.12, 95% CI: 1.01-1.24, P=0.031), hypertension (OR: 4.86, 95% CI: 1.16-20.49, P=0.031), fasting blood glucose (OR: 1.23, 95% CI: 1.03-1.48, P=0.025), WHR (OR: 2.53, 95% CI: 1.03-6.22, P=0.044), and MLR (OR: 1.91, 95% CI: 1.18-3.08, P=0.008) are independent risk factors for DKD (P < 0.05). Conversely, A/G (OR: 0.13, 95% CI: 0.02-0.76, P=0.024) and Metrnl (OR: 0.99, 95% CI: 0.98-1.00, P=0.001) have been identified as protective factors against DKD. Furthermore, the level of Metrnl was negatively correlated with the severity of DKD (rs=-0.447, P<0.001). The area under receiver operating characteristic (ROC) curves for the diagnostic accuracy of Metrnl for DKD is 0.765 (95% CI: 0.686-0.844).

Conclusion

The duration of the disease, hypertension, fasting blood glucose, WHR, and MLR are major risk factors for DKD. Metrnl and A/G are protective factors for DKD. Serum Metrnl concentrations are inversely correlated with DKD severity.

Identification of Ribonuclease 6 as an immunoinflammatory key gene associated with the glomerular injury in diabetic nephropathy

Diabetic nephropathy is one of the major causes of end-stage renal disease, and the pathogenesis of the disease has not been elucidated. While the immunoinflammatory response plays an essential role in the progression of diabetic nephropathy. Glomerular expression dataset in diabetic nephropathy was obtained from the GEO database. Differentially expressed genes were identified and functional enrichment analysis was performed to find genes associated with immunity and inflammation from them. The hub genes of immunoinflammatory were identified using MCODE after establishing the PPI network and gene expression was verified with diabetic nephropathy model rats. Xcell was used to assign immune cells to diabetic nephropathy glomerular samples to detect significant changes in immune cells and to analyze correlations with the hub gene. We found 120 DEGs associated with immunity and inflammation, Ribonuclease 6 was the Hub gene with the highest MCODE score. Xcell analysis revealed significant changes of immune cells in DN glomeruli, including upregulated Activated DCs, Conventional DCs, CD4+ Tem, Epithelial cells, Macrophages, Macrophages M1, and Memory B-cells. RNase6 expression showed the highest positive correlation with Macrophages M1, Activated DCs, and Conventional DCs. We verified through the Nephroseq v5 database that RNase6 expression was elevated in DN glomeruli and negatively correlated with glomerular filtration rate. Animal studies revealed that the kidney of DN model rats showed increased RNase6 expression together with inflammatory factor TNF-alpha and chemokine MCP-1. Our study identified RNase6 as a diagnostic and prognostic biomarker for diabetic nephropathy and found that it may play an essential role in the immunoinflammatory damage to the glomerulus.