Suppression of mesangial cell proliferation and extracellular matrix production in streptozotocin-induced diabetic mice by adiponectin in vitro and in vivo

Diabetic fibrosis

Diabetes-associated morbidity and mortality is predominantly due to complications of the disease that may cause debilitating conditions, such as heart and renal failure, hepatic insufficiency, retinopathy or peripheral neuropathy. Fibrosis, the excessive and inappropriate deposition of extracellular matrix in various tissues, is commonly found in patients with advanced type 1 or type 2 diabetes, and may contribute to organ dysfunction. Hyperglycemia, lipotoxic injury and insulin resistance activate a fibrotic response, not only through direct stimulation of matrix synthesis by fibroblasts, but also by promoting a fibrogenic phenotype in immune and vascular cells, and possibly also by triggering epithelial and endothelial cell conversion to a fibroblast-like phenotype. High glucose stimulates several fibrogenic pathways, triggering reactive oxygen species generation, stimulating neurohumoral responses, activating growth factor cascades (such as TGF-β/Smad3 and PDGFs), inducing pro-inflammatory cytokines and chemokines, generating advanced glycation end-products (AGEs) and stimulating the AGE-RAGE axis, and upregulating fibrogenic matricellular proteins. Although diabetes-activated fibrogenic signaling has common characteristics in various tissues, some organs, such as the heart, kidney and liver develop more pronounced and clinically significant fibrosis. This review manuscript summarizes current knowledge on the cellular and molecular pathways involved in diabetic fibrosis, discussing the fundamental links between metabolic perturbations and fibrogenic activation, the basis for organ-specific differences, and the promises and challenges of anti-fibrotic therapies for diabetic patients.

Renoprotective effects of brown adipose tissue activation in diabetic mice

BACKGROUND

Brown adipose tissue (BAT) has been regarded as a potential target organ to combat obesity and related metabolic disorders. However, the effect of BAT activation on the development of diabetic kidney disease (DKD) remains unclear.

METHODS

Diabetic mice were induced by streptozotocin (STZ) combined with a high-fat diet. To activate BAT, mice were administered 1 mg/kg per day, i.p., CL316,243, a β₃ -adrenergic receptor agonist, for 4 weeks. Blood glucose, serum lipids, adipokines, 24-hour urinary albumin, 8-hydroxydeoxyguanosine (8-OHdG), and circulating microRNA (miRNA) levels were analyzed, in addition to renal pathology. Histological changes (fibrosis, inflammation) were evaluated in the kidneys, as was the expression of oxidative stress-related genes. Renal signaling pathways (fibroblast growth factor [Fgf]21/β-klotho/FGF receptor 1c and AMP-activated protein kinase[AMPK]/sirtuin 1 [Sirt1]/peroxisome proliferator-activated receptor-γ coactivator-1α [Pgc1α]) were also evaluated.

RESULTS

Compared with untreated STZ-diabetic mice, CL316,243 treatment reduced blood glucose, albeit not significantly (20.58 ± 3.55 vs 23.60 ± 3.90 mM), and significantly decreased triglycerides and low-density lipoprotein cholesterol and increased high-density lipoprotein cholesterol. Simultaneously, BAT activation significantly decreased 24-hour urinary albumin (34.21 ± 6.28 vs 70.46 ± 15.81 μg/24 h; P < 0.05) and 8-OHdG, improved renal fibrosis, inflammation, and oxidative stress, and ameliorated renal morphological abnormalities. In addition to enhancing BAT activity, CL316,243 significantly increased serum adiponectin concentrations and renal Fgf21 sensitivity, and reactivated the renal AMPK/Sirt1/Pgc1α signaling pathway. Furthermore, CL316,243 treatment increased levels of some circulating miRNAs and downregulated expression of their target genes in the kidney.

CONCLUSIONS

Activating BAT could improve kidney injury in diabetic mice via metabolic improvements and renal AMPK activation by beneficial adipokines and miRNAs.

Tangshen Formula Treatment for Diabetic Kidney Disease by Inhibiting Racgap1-stata5-Mediated Cell Proliferation and Restoring miR-669j-Arntl-Related Circadian Rhythm

Background

The aim of this study was to investigate the underlying mechanisms of Tangshen formula (TSF) for treatment of diabetic kidney disease (DKD).

Material/Methods

Microarray dataset GSE90842 was collected from the Gene Expression Omnibus database, including renal cortical tissues from normal control (NC), DKD, and DKD mice given TSF for 12 weeks (TSF) (n=3). Differentially-expressed genes (DEGs) were identified using LIMMA method. A protein-protein interaction (PPI) network was constructed using data from the STRING database followed by module analysis. The Mirwalk2 database was used to predict the underlying miRNAs of DEGs. Function enrichment analysis was performed using the DAVID tool.

Results

A total of 2277 and 2182 genes were identified as DEGs between DKD and NC or TSF groups, respectively. After overlap, 373 DEGs were considered as common in 2 comparison groups. Function enrichment indicated common DEGs were related to cell proliferation (Asf1b, anti-silencing function 1B histone chaperone; Anln, anillin, actin-binding protein; Racgap1, Rac GTPase activating protein 1; and Stat5, signal transducer and activator of transcription 5) and circadian rhythm (Arntl, aryl hydrocarbon receptor nuclear translocator-like). Racgap1 was considered as a hub gene in the PPI network because it could interact with Asf1b, Anln, and Stat5. Arntl was regulated by miR-669j in the miRNA-DEGs network and this miRNA was also a DEG in 2 comparisons.

Conclusions

TSF may be effective for DKD by inhibiting Racgap1-stata5-mediated cell proliferation and restoring miR-669j-Arntl-related circadian rhythm.

The Expression of miR-192 and Its Significance in Diabetic Nephropathy Patients with Different Urine Albumin Creatinine Ratio

OBJECTIVE

To investigate the expression of miR-192 and its significance in diabetic nephropathy (DN) patients.

METHODS

464 patients with type 2 diabetes mellitus (T2DM) were divided into normal albuminuria group (NA, n = 157), microalbuminuria group (MA, n = 159), and large amount of albuminuria group (LA, n = 148). 127 healthy persons were selected as the control group (NC, n = 127). The serum miR-192 levels were detected by Real-Time PCR and transforming growth factor-β1 (TGF-β1) and fibronectin (FN) were detected by enzyme-linked immunosorbent assay. The relationships among these parameters were analyzed by Pearson correlation analysis and multiple linear regression analysis.

RESULTS

The miR-192 in the LA group was significantly lower than other groups, which was lower in the MA group than in the NA group (P < 0.01). The TGF-β1 and FN in the LA group were significantly higher than other groups, which were higher in the MA group than in the NA group (P < 0.01). The expression of miR-192 was negatively correlated with TGF-β1, FN, and Ln (UACR) and miR-192, TGF-β1, and FN were independent relevant factors affecting Ln (UACR) in T2DM (P < 0.01).

CONCLUSIONS

These findings indicate that the levels of miR-192 were lower accompanied by the decrease of urine albumin creatinine ratio (UACR) and the association between miR-192 and nephritic fibrosis in DN.