The expression of POMC and AgRP in brain and kidney tissues at different stages of diabetic nephropathy rats

Objective To explore the changes of proopiomelanocortin (POMC) and Agouti-Related Peptide (AgRP) expression in brain and kidney tissues under insulin intervention at different stages of diabetic nephropathy (DN) rats. Methods The male Sprague-Dawley (SD) rats of DN were treated with high-fat diet for 8 weeks and induced by intraperitoneally injection of streptozotocin (30 mg/kg) for one time. Then DN rats were also injected insulin subcutaneously at 2–5 U/(kg·24 h) from initiation of the streptozotocin. Kidney tissue, blood sample, and 24 h-urine were collected to detect the ratio of kidney/body weight, blood glucose and 24-h urinary albumin excretion rate at different stages (4, 8, 12, and 16 weeks). Immunohistochemistry assay was used to measure the expression of POMC and AgRP at different stages of DN rats. Results The DN rats were established successfully. With the progression of DN, blood glucose, 24-h urinary albumin excretion rate and kidney body weight ratio increased significantly, while decreased when insulin was injected. Immunohistochemistry showed that the expression levels of POMC were decreased gradually in brain and kidney tissues. Conversely, the expression of AgRP in kidney was highest at week 8 and then decreased gradually. The effect of insulin on normalizing POMC and AgRP expression in brain and renal tissues was also observed in DKD rats. Conclusion With the progression of DN, the expression of POMC and AgRP in kidney tissues was observed at different stages of disease, and their expressions were significantly normalized by insulin. The mechanism of in situ expression of POMC and AGRP in kidney to the progression of DN needs further investigations.

Key profibrotic and pro-inflammatory pathways in the pathogenesis of diabetic kidney disease

Diabetes is a noncommunicable disease and arguably represents the greatest pandemic in human history. Diabetic kidney disease (DKD) is seen in both type 1 and type 2 diabetes and can be detected in up to 30–50% of diabetic subjects. DKD is a progressive chronic kidney disease (CKD) and is a leading cause of mortality and morbidity in patients with diabetes. Renal fibrosis and inflammation are the major pathological features of DKD. There are a large number of independent and overlapping profibrotic and pro-inflammatory pathways involved in the pathogenesis and progression of DKD. Among these pathways, the transforming growth factor-β (TGF-β) pathway plays a key pathological role by promoting fibrosis. Sirtuin-1 (SIRT1) is a protein deacetylase that has been shown to be renoprotective with an anti-inflammatory effect. It is postulated that a reduction in renal SIRT1 levels could play a key role in the pathogenesis of DKD and that restoration of SIRT1 will attenuate DKD. Cell division autoantigen 1 (CDA1) synergistically enhances the profibrotic effect of TGF-β in DKD by regulating the expression of the TGF-β type I receptor (TβRI). CDA1 has also been found to be an inhibitor of SIRT1 in the DNA damage response. Indeed, targeting CDA1 in experimental DKD not only attenuates diabetes-associated renal fibrosis but also attenuates the expression of key pro-inflammatory genes such as tumor necrosis factor-α (TNF-α) and Monocyte Che moattractant Protein-1 (MCP-1). In conclusion, there is a large body of experimental data to support the view that targeting CDA1 is a superior approach to directly targeting TGF-β in DKD since it is not only safe but also efficacious in retarding both fibrosis and inflammation.

A point mutation of mitochondrial genes in diabetes and deafness with focal segmental glomerular sclerosis

Deafness, diabetes and proteinuria are typically understood to be an uncommon combination. Here, we reported a 26-year-old woman with a history of persistent deafness, diabetes mellitus, and proteinuria. The diagnosis mainly depends on clinical symptoms, but the cause of the disease should be examined. The histological finding in renal biopsy showed secondary focal segmental glomerular sclerosis (FSGS), but not classic diabetic nephropathy. Further pathogeny was found. Subsequently, a 3243A>G mutation in the mitochondrial DNA was found. Thus, the diagnosis of maternally inherited deafness and diabetes (MIDD) was considered. Ineffective and unnecessary immunosuppression can be avoided through timely diagnosis. Long-term treatment of CoQ10 can be useful in MIDD patients.

Sitagliptin ameliorates ER stress in diabetic kidney disease through upregulation of SIRT1

Objectives Endoplasmic reticulum (ER) stress plays a significant role in the progression of diabetic kidney disease (DKD), and dipeptidyl peptidase-4 (DPP4) inhibitors are widely used antihyperglycemic agents, exerting renal beneficial effects in DKD. Here, we investigated the role of DPP4 inhibitor Sitagliptin (Sita) in ER homeostasis in the kidneys of diabetic DBA2/J (D2) mice and in albumin-stimulated HK-2 cells. Methods and Results ER stress was observed both in vivo and in vitro, as reflected by notably increased glucose-regulated protein of 78 kDa (GRP78), CHOP, high phosphorylation of PERK (p-PERK), and cleaved caspase3 (c-CASP3), whereas Sita effectively attenuated these disorders. Meanwhile, Sita increased the expression of SIRT1 both in vivo and in vitro. To further validate the potential effects of SIRT1 in regulating ER stress, we regulated SIRT1 by siRNA and overexpressed plasmids in albumin-overloaded HK-2 cells. Elevated SIRT1 alleviated albumin-induced ER stress, while decreased SIRT1 further aggravated ER stress in albumin-treated HK-2 cells. Conclusion The results suggest that a novel mechanism links the DPP4 enzyme to ER stress during tubular injury in DKD and highlight that SIRT1 may be a potential target for managing DKD.

NRF2: A potential target for the treatment of diabetic nephropathy

One of the major complications of diabetes mellitus is diabetic nephropathy (DN), the pathogenesis of which is primarily driven by oxidative stress. As a major regulator of antioxidant responses, the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) has recently attracted much interest. NRF2 is a primary defense mechanism against the cytotoxic effects of oxidative stress, involving heterogeneous detoxification, the production of antioxidants and anti-inflammatory molecules, DNA repair, nuclear chaperones, and proteasome systems. A myriad of studies in pre-clinical models of DN have consistently demonstrated a beneficial effect of NRF2 activation, suggesting that NRF2 is likely a promising target for treating DN. This has been further supported by findings from clinical trials of bardoxolone methyl, an activator of NRF2, despite the unexpected adverse cardiovascular effects. This review summarizes the support for therapeutic targeting of NRF2 in DN and emphasizes the need for the optimization of NRF2-based treatment with the minimization of potential adverse effects.

Pathogenesis of diabetic kidney disease

Diabetic kidney disease (DKD) is characterized by an accumulation of extracellular matrix proteins such as collagen and fibronectin in the kidney, resulting in tubulointerstitial fibrosis, glomerular mesangial hypertrophy and expansion, thickening of the glomerular basement membrane, podocyte foot process effacement, and inflammation due to the infiltration of monocytes and macrophages. All of these factors contribute to kidney function loss and can ultimately lead to progressive chronic kidney disease and kidney failure. In the review, we summarize the current state of knowledge in the pathogenesis of diabetic kidney disease to include the impact of genetic and environmental factors, hemodynamic changes, glycemic control, inflammation, proteinuria and novel mechanisms such as non-coding RNAs and lipotoxicity.

Simultaneous membranous nephropathy and diabetic nephropathy occurrence in a patient: A case report

Membranous nephropathy (MN) is the most common glomerular disease in adults and is constantly associated with the occurrence of nephrotic syndrome. While diabetic kidney disease (DKD) and diabetic nephropathy (DN), which often occur in diabetic patients, are considered as the major causes of end-stage kidney disease. Actually, MN often occurs in patients with diabetes mellitus (DM), but to obtain a clear differential diagnosis without a renal biopsy has become difficult. Here we report the case of a female diabetic patient who developed both MN and DN simultaneously.