Glucosamine inhibits extracellular matrix accumulation in experimental diabetic nephropathy

Upregulation of Piezo2 and increased extracellular matrix protein in diabetic kidney disease mice

Mechanical forces such as glomerular hyperfiltration are crucial in the pathogenesis and progression of diabetic kidney disease. Piezo2 is a mechanosensitive cation channel and plays a major role in various biological and pathophysiological phenomena. We previously reported Piezo2 expression in mouse and rat kidneys and its alteration by dehydration and hypertension. To elucidate the alteration of Piezo2 expression and its consequences in a mouse model of diabetic kidney disease, we used high salt-fed male KK-Ay mice, an accelerated genetic model of diabetic kidney disease. KK-Ay mice exhibited marked obesity, hyperglycemia, elevated blood pressure, higher creatinine clearance, and overt albuminuria. Histopathological analysis revealed glomerular hypertrophy, mesangial expansion, macrophage infiltration, tubular vacuolization, and interstitial fibrosis. The mRNA and protein expression analyses revealed (1) increased fibronectin protein expression in the glomerular areas, (2) upregulated Piezo2 expression in the glomerular mesangial cells and interstitial region, (3) increased Piezo2 and the fibronectin-coding gene Fn1 mRNA, and (4) a strong correlation of Piezo2 expression with that of Fn1 in the kidneys of diabetic kidney disease mice. Piezo2 upregulation and fibronectin accumulation were alleviated by an angiotensin II receptor blocker. In accordance with these in vivo results, in vitro study demonstrated that Piezo2 overexpression increased fibronectin production in HEK293T cells. In conclusion, we demonstrated that Piezo2 expression was upregulated in glomerular mesangial cells in a mouse model of diabetic kidney disease. Our results suggest that Piezo2 contributes to the progression of diabetic kidney disease by mediating glomerular fibronectin production, leading to glomerulosclerosis. Hyperfiltration is crucial in the pathogenesis of diabetic kidney disease. We showed that Piezo2 expression is upregulated in mesangial cells of diabetic kidney disease mice with glomerular fibronectin accumulation. Piezo2 overexpression increased fibronectin production in HEK293T cells. Piezo2 may contribute to diabetic kidney disease progression by mediating glomerular fibronectin production.

Integrating network pharmacology, molecular docking, and animal studies to investigate the protective effect of astragalus polysaccharide on fluoride-induced renal injury in rats

Fluoride is an essential trace element required for normal physiological functions and holds significant importance for human health. However, excessive fluoride intake can lead to renal damage, for which effective prevention and therapeutic strategies remain scarce. Astragalus polysaccharide (APS), a major bioactive component of the traditional Chinese herb Astragalus membranaceus, possesses pharmacological properties including anti-inflammatory, antiviral, and antioxidant activities. In this study, we investigated the protective effects of APS against fluoride-induced renal injury in vivo experiment. Additionally, network pharmacology and molecular docking techniques were employed to predict its potential mechanisms of action, while the protein expression levels of key target molecules were validated. The results demonstrated that APS intervention significantly alleviated renal injury and oxidative stress induced by sodium fluoride (NaF) in rats. Key targets involved in the amelioration of fluoride-induced renal damage by APS included STAT3, Caspase-3, JUN, MMP1, and PTGS2. Molecular docking analysis revealed high-affinity binding between APS and these core targets. Immunohistochemical and Western blot analysis further confirmed that APS suppressed the expression of pro-apoptotic proteins STAT3, Caspase-3, JUN, and MMP1 while enhancing the expression of the anti-apoptotic protein PTGS2. Overall, our findings suggest that APS alleviates fluoride-induced renal injury by modulating multiple targets, with the potential mechanism linked to the regulation of apoptotic processes. This study provides a theoretical basis for the prevention and treatment of fluoride toxicity.

Long-term glucosamine supplementation aggravates atrial fibrillation susceptibility by impairing AMPK signaling

AIMS

Glucosamine, a widely used dietary supplement, has been linked to potential cardiovascular risks, including atrial fibrillation (AF). This study aimed to investigate the effects of long-term glucosamine supplementation on AF susceptibility and the underlying mechanisms.

MATERIALS AND METHODS

C57BL/6 J mice were treated with low-dose (15 mg/kg/day) or high-dose (250 mg/kg/day) glucosamine via drinking water for 6 weeks. AF susceptibility was assessed through transesophageal electrical stimulation. Atrial remodeling was characterized through electrophysiological and echocardiography studies, histological analysis, and molecular examination. AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR) was used to validation the underlying mechanism in mice and isolated neonatal atrial cardiomyocytes.

KEY FINDINGS

Long-term high-dose glucosamine supplementation increased AF susceptibility in mice, as indicated by an elevated AF incidence and duration. Glucosamine induced notable electrical remodeling, evidenced by intra-atrial conduction slowing (P wave duration, amplitude, and area), likely attributable to reduced conduction velocity, as confirmed by two-dimensional electrical mapping. Structural remodeling including increased left atrial weight, cardiomyocyte hypertrophy and fibrosis was evident in the atria of glucosamine-treated mice, despite unaffected cardiac function. Mechanistically, glucosamine suppressed atrial AMPK signaling, leading to lipid and glycogen accumulation. Intriguingly, despite impaired atrial AMPK signaling, high-dose glucosamine improved systemic insulin sensitivity. Pharmacological activation of AMPK with AICAR mitigated glucosamine-induced AF susceptibility and associated pathological changes both in vivo and in vitro.

SIGNIFICANCE

Our findings demonstrate that long-term glucosamine supplementation enhances AF susceptibility, potentially by impairing atrial AMPK signaling, underscoring the importance of caution in the utilization of glucosamine.

Mizagliflozin ameliorates diabetes induced kidney injury by inhibitor inhibit inflammation and oxidative stress

BACKGROUND

Mizagliflozin (MIZ) is a specific inhibitor of sodium-glucose cotransport protein 1 (SGLT1) originally developed as a medication for diabetes.

AIM

To explore the impact of MIZ on diabetic nephropathy (DN).

METHODS

Diabetic mice were created using db/db mice. They were administered either a low dose (0.5 mg/kg) or a high dose (1.0 mg/kg) of the SGLT1 inhibitor MIZ via stomach gavage for 8 weeks. Subsequently, mesangial cells (MCs) were isolated and subjected to high glucose conditions in culture to assess the effects of MIZ on DN.

RESULTS

The results showed that low doses of MIZ significantly reduced albuminuria to a level comparable to that achieved with high doses in db/db mice. High doses of MIZ led to a substantial increase in body weight in mice, along with decreased blood glucose levels and food intake. Moreover, the intervention with high-dose MIZ notably decreased the expression of extracellular matrix genes, such as collagen type 1 alpha 1 mRNA levels. While the expression of SGLT1 increased after exposure to high glucose, it decreased following treatment with MIZ. Furthermore, MIZ intervention was more effective in improving lactate dehydrogenase levels in MCs induced by high glucose compared to canagliflozin. MIZ also significantly elevated levels of antioxidant enzymes superoxide dismutase, catalase, and glutathione, while reducing malondialdehyde levels.

CONCLUSION

These findings indicate that MIZ can ameliorate DN by inhibiting SGLT1, inflammation, and oxidative stress.

Exploring the molecular mechanism of berberine for treating diabetic nephropathy based on network pharmacology

BACKGROUND AND PURPOSE

Diabetic nephropathy (DN) is a prevalent complication of diabetes mellitus characterized by hyperglycemia, hyperlipidemia, albuminuria and edema. Increasing evidence indicated that berberine (BBR) could alleviate the occurrence and development of DN. However, the molecular mechanism underlying the beneficial effects of BBR in the treatment of DN remains unclear.

METHODS

The online public databases were chosen to screen the relevant targets of BBR and DN and the screened overlapped targets were analyzed by GO enrichment analysis, KEGG enrichment analysis and protein-protein interaction network analysis. The interaction between BBR and the key proteinwas verified by molecular docking and cellularthermalshiftassay. Additionally, the expression of key proteins and related indicators of DN were verified by immunofluorescence and western blot in vitro and in vivo.

RESULTS

We successfully identified 92 overlapped targets of BBR and DN based on network pharmacology. Notably, VEGFR2 was identified to be the main target of BBR. Meanwhile, we found that BBR exhibited a high binding affinity to VEGFR2 protein, as confirmed by molecular docking and CETSA. This binding led to interfering with the PI3K/AKT/mTOR signaling pathway. In addition, we found that BBR could inhibit the abnormal proliferation of mesangial cells and reduce the expression of downstream pathway protein in vitro and in vivo. Finally, BBR was found to effectively lower the level of blood glucose and improve kidney function in mice, highlighting its potential as a therapeutic agent for the treatment of DN.

CONCLUSION

Berberine interfered the PI3K/AKT/mTOR signaling pathway via targeting VEGFR2 protein, further led to the inhibition of abnormal proliferation of mesangial cells and ultimately resulted in improved renal function.