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Chronic inflammation induced by obesity plays a crucial role in the pathogenesis of insulin resistance. The infiltration of macrophages into adipose tissues contributes to adipose tissue inflammation and insulin resistance. Kaempferol, a flavonoid present in various vegetables and fruits, has been shown to possess remarkable anti-inflammatory properties. In this study, we used leptin receptor-deficient obese mice (db/db) as an insulin-resistant model and investigated the effects of kaempferol treatment on obesity-induced insulin resistance. Our findings revealed that the administration of kaempferol (50 mg/kg/day, for 6 weeks) significantly reduced body weight, fat mass, and adipocyte size. Moreover, it effectively ameliorated abnormal glucose tolerance and insulin resistance in db/db mice. In the adipose tissue of obese mice treated with kaempferol, we observed a reduction in macrophage infiltration and a downregulation of mRNA expression of M1 marker genes TNF-α and IL-1β, accompanied by an upregulation of Arg1 and IL-10 mRNA expression. Additionally, kaempferol treatment significantly inhibited the STING/NLRP3 signaling pathway in adipose tissue. In vitro experiments, we further discovered that kaempferol treatment suppressed LPS-induced inflammation through the activation of NLRP3/caspase 1 signaling in RAW 264.7 macrophages. Our results suggest that kaempferol may effectively alleviate inflammation and insulin resistance in the adipose tissue of db/db mice by modulating the STING/NLRP3 signaling pathway.
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Protection of podocytes is one of the important means to delay the progression of diabetic nephropathy (DN), and glucagon-like peptide-1 (GLP-1) has been shown to have a protective effect on the kidney in DN models, but whether it has a protective effect on podocytes and the potential mechanisms of action remain largely unknown. In the present study, we established a type 2 diabetes mellitus (T2DM) mouse model by high-fat diet feeding combined with streptozotocin (STZ) induction and administered the intervention for 14 weeks. We found that liraglutide significantly ameliorated podocyte injury in DN mice. Mechanistically, we detected glucagon-like peptide-1 receptor (GLP-1R) protein expression levels in kidney tissues by immunohistochemical staining, immunofluorescence staining, and western blotting and found that podocytes could express GLP-1R and liraglutide treatment could restore GLP-1R expression in the kidney tissues of DN mice. Furthermore, we found that NLRP3-induced inflammation and pyroptosis were positively correlated with podocyte injury in DN mice, and liraglutide inhibited the expression of NLRP3-induced inflammation and pyroptosis-related proteins. Our results suggest that liraglutide protects DN mouse podocytes by regulating GLP-1R in renal tissues and by regulating NLRP3-induced inflammation and pyroptosis.
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Obesity is a major cause of type 2 diabetes. Transition from obesity to type 2 diabetes manifests in the dysregulation of hormones controlling glucose homeostasis and inflammation. As metabolism is a dynamic process that changes across 24 h, we assessed diurnal rhythmicity in a panel of 10 diabetes-related hormones. Plasma hormones were analysed every 2 h over 24 h in a controlled laboratory study with hourly isocaloric drinks during wake. To separate effects of body mass from type 2 diabetes, we recruited three groups of middle-aged men: an overweight (OW) group with type 2 diabetes and two control groups (lean and OW). Average daily concentrations of glucose, triacylglycerol and all the hormones except visfatin were significantly higher in the OW group compared to the lean group (P < 0.001). In type 2 diabetes, glucose, insulin, C-peptide, glucose-dependent insulinotropic peptide and glucagon-like peptide-1 increased further (P < 0.05), whereas triacylglycerol, ghrelin and plasminogen activator inhibitor-1 concentrations were significantly lower compared to the OW group (P < 0.001). Insulin, C-peptide, glucose-dependent insulinotropic peptide and leptin exhibited significant diurnal rhythms in all study groups (P < 0.05). Other hormones were only rhythmic in 1 or 2 groups. In every group, hormones associated with glucose regulation (insulin, C-peptide, glucose-dependent insulinotropic peptide, ghrelin and plasminogen activator inhibitor-1), triacylglycerol and glucose peaked in the afternoon, whereas glucagon and hormones associated with appetite and inflammation peaked at night. Thus being OW with or without type 2 diabetes significantly affected hormone concentrations but did not affect the timing of the hormonal rhythms.
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Objective
We aimed to evaluate whether thyroid hormones, autoimmune and thyroid homeostasis status were related to bone turnover in type 2 diabetes.
Methods
The data were obtained from a cross-sectional study, the METAL study. In this study, 4209 participants (2059 men and 2150 postmenopausal women) with type 2 diabetes were enrolled. Thyroid function, thyroid antibodies and three bone turnover markers (BTMs), including a large N-mid fragment of osteocalcin (N-MID osteocalcin), β-C-terminal cross-linked telopeptides of type I collagen (β-CTX) and procollagen type I N-terminal propeptide (P1NP), were measured. Thyroid homeostasis parameters, including the sum activity of step-up deiodinases (SPINA-GD), thyroid secretory capacity (SPINA-GT), Jostel’s TSH index (TSHI) and the thyrotroph thyroid hormone resistance index (TTSI), were calculated. The associations of thyroid parameters with BTMs were analyzed using linear regression.
Results
Free and total triiodothyronine were positively associated with N-MID osteocalcin and P1NP in both sexes and positively associated with β-CTX in postmenopausal women. Thyroid-stimulating hormone was negatively associated with β-CTX in postmenopausal women, and free thyroxine was negatively associated with N-MID osteocalcin and P1NP in men. SPINA-GD was positively associated with N-MID osteocalcin and P1NP in both sexes. There was a positive relationship of SPINA-GT with β-CTX, a negative relationship of TTSI with β-CTX, and a negative relationship of TSHI with β-CTX and P1NP in postmenopausal women.
Conclusions
Among men and postmenopausal women with type 2 diabetes, significant associations were observed between N-MID osteocalcin, β-CTX and P1NP with thyroid function and thyroid homeostasis. Further prospective studies are warranted to understand the causal relationship and underlying mechanism.
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Objectives
The activation of immune cells plays a significant role in the progression of type 2 diabetes. This study aimed to investigate the potential role of myeloid-derived suppressor cells (MDSCs) and T-regulatory cells (Tregs) in type 2 diabetes.
Methods
A total of 61 patients diagnosed with type 2 diabetes were recruited. Clinical characteristics were reviewed and peripheral blood samples were collected. We calculated the percentage of different cells. Frequencies of MDSC subsets refered to the percentage of G-MDSCs (CD15+CD33+CD11b+CD14-HLA-DR-/low) in CD45 positive cells and the percentage of M-MDSCs (CD14+CD15-CD11b+CD33+HLA-DR-/low) in lymphocytes plus monocytes.
Results
Frequencies of programmed cell death ligand 1-positive granulocytic MDSCs (PD-L1+ G-MDSCs), programmed cell death ligand 2-positive monocytic MDSCs (PD-L2+ M-MDSCs), PD-L2+ G-MDSC, and programmed cell death protein 1-positive Tregs (PD-1+Tregs) were decreased in patients with type 2 diabetes. The frequency of PD-1+ Tregs was positively related to PD-L2+ M-MDSCs (r= 0.357, P = 0.009) and negatively related to HbA1c (r = -0.265, P = 0.042), fasting insulin level (r = −0.260, P = 0.047), and waist circumference (r = −0.373, P = 0.005).
Conclusions
Decreased PD-L2+ M-MDSCs and PD-1+ Tregs may promote effector T cell activation, leading to chronic low-grade inflammation in type 2 diabetes. These findings highlight the contribution of MDSCs and Tregs to the immunopathogenesis of type 2 diabetes and suggest their potential as targets for new therapeutic approaches.
