Metformin is one of the most widely prescribed hypoglycemic drugs and has the potential to treat many diseases. More and more evidence shows that metformin can regulate the function of macrophages in atherosclerosis, including reducing the differentiation of monocytes and inhibiting the inflammation, oxidative stress, polarization, foam cell formation and apoptosis of macrophages. The mechanisms by which metformin regulates the function of macrophages include AMPK, AMPK independent targets, NF-κB, ABCG5/8, Sirt1, FOXO1/FABP4 and HMGB1. On the basis of summarizing these studies, we further discussed the future research directions of metformin: single-cell RNA sequencing, neutrophil extracellular traps (NETs), epigenetic modification, and metformin-based combination drugs. In short, macrophages play an important role in a variety of diseases, and improving macrophage dysfunction may be an important mechanism for metformin to expand its pleiotropic pharmacological profile. In addition, the combination of metformin with other drugs that improve the function of macrophages (such as SGLT2 inhibitors, statins and IL-1β inhibitors/monoclonal antibodies) may further enhance the pleiotropic therapeutic potential of metformin in conditions such as atherosclerosis, obesity, cancer, dementia and aging.

Metformin has been used in diabetes for more than 60 years and has excellent safety in the therapy of human type 2 diabetes (T2D). There is growing evidence that the beneficial health effects of metformin are beyond its ability to improve glucose metabolism. Metformin not only reduces the incidence of cardiovascular diseases (CVD) in T2D patients, but also reduces the burden of atherosclerosis (AS) in pre-diabetes patients. Vascular smooth muscle cells (VSMCs) function is an important factor in determining the characteristics of the entire arterial vessel. Its excessive proliferation contributes to the etiology of several types of CVD, including AS, restenosis, and pulmonary hypertension. Current studies show that metformin has a beneficial effect on VSMCs function. Therefore, this review provides a timely overview of the role and molecular mechanisms by which metformin acts through VSMCs to protect CVD.

Diabetic nephropathy (DN) is the principal cause of end-stage renal disease and results in high morbidity and mortality in patients, causing a large socioeconomic burden. Multiple factors, such as metabolic abnormalities, inflammation, immunoregulation and genetic predisposition, contribute to the pathogenesis of DN, but the exact mechanism is unclear, and the therapeutic strategies are not satisfactory. Accordingly, there is an unmet need for new therapeutic targets and strategies for DN. MicroRNAs (miRNAs) act as major epigenetic mechanisms that regulate gene expression and provide novel insights into our understanding of the molecular and signaling pathways that are associated with various diseases, including DN. Studies in the past decade have shown that different miRNAs affect the progression of DN by modulating different aspects of immune and inflammatory responses. Therefore, in this review, we summarized the pivotal roles of miRNAs in inflammatory and immune processes, with an integrative comprehension of the detailed signaling network. Additionally, we discussed the possibilities and significance of these miRNAs as therapeutic targets in the treatment of DN. This review will facilitate the identification of new therapeutic targets and novel strategies that can be translated into clinical applications for DN treatment.

Background: Fibrosis and inflammation in the renal tubular epithelial cells (TECs) are key contributors to the pathology of diabetic kidney disease (DKD). Nevertheless, the precise triggers of these processes remain unclear. This study aimed to explore the role of interferon‐stimulated gene 15 (ISG15) in the injury of TECs induced by high glucose (HG) conditions and its implications for the development of DKD.Methods: ISG15 knockout (ISG15 KO) mice injected with streptozotocin‐treated mice on a high‐fat diet were used to investigate its role in DKD. Cellular models with ISG15 knockdown were exposed to HG conditions to assess the effects of ISG15 on cellular responses. Subsequently, we evaluated the impact of ISG15 on pyroptosis, a form of programmed cell death, to understand its potential role in DKD pathology. Furthermore, RNA sequencing (RNA‐seq) and molecular biology techniques were employed to explore the signalling pathways potentially regulated by ISG15.Results: We first confirmed an up‐regulation of ISG15 within the renal tubule in DKD. The deletion of ISG15 alleviated renal functional damage, fibrosis and inflammation, which correlated with reduced ISGylation levels. Mechanistic investigation revealed that HG stimulation in TECs disrupted the mtDNA–cGAS–STING signalling, which exacerbates the DKD through the NLRP3–CASP1–GSDMD axis. Furthermore, we uncovered a bidirectional regulatory loop between STING and ISG15, with STING enhancing ISG15 expression upstream and ISG15 modulating STING expression through ISGylation.Conclusion: ISG15–mtDNA–STING emerges as a critical hub that integrates the processes of pyroptosis, fibrosis and inflammation. Therapeutic interventions that target this signalling network at various levels may pave the way for innovative treatments for DKD.Key points: ISG15 is highly expressed in both DKD mice and renal tubular epithelial cell cultured in HG condition. ISG15 promotes DKD pyroptosis via NLRP3–CASP1–GSDMD axis. ISG15–mtDNA–STING emerges as a critical hub that integrates the processes of pyroptosis.

High glucose (HG) is one of the basic factors of diabetic nephropathy (DN), which leads to high morbidity and disability. During DN, the expression of glomerular glucose transporter 1 (GLUT1) increases, but the relationship between HG and GLUT1 is unclear. Glomerular mesangial cells (GMCs) have multiple roles in HG‐induced DN. Here, we report prominent glomerular dysfunction, especially GMC abnormalities, in DN mice, which is closely related to GLUT1 alteration. In vivo studies have shown that BBR can alleviate pathological changes and abnormal renal function indicators of DN mice. In vitro, BBR (30, 60 and 90 μmol/L) not only increased the proportion of G1 phase cells but also reduced the proportion of S phase cells under HG conditions at different times. BBR (60 μmol/L) significantly reduced the expression of PI3K‐p85, p‐Akt, p‐AS160, membrane‐bound GLUT1 and cyclin D1, but had almost no effect on total protein. Furthermore, BBR significantly declined the glucose uptake and retarded cyclin D1‐mediated GMC cell cycle arrest in the G1 phase. This study demonstrated that BBR can inhibit the development of DN, which may be due to BBR inhibiting the PI3K/Akt/AS160/GLUT1 signalling pathway to regulate HG‐induced abnormal GMC proliferation and the cell cycle, supporting BBR as a potential therapeutic drug for DN.