l-thyroxine attenuates extracellular Hsp90α-induced vascular endothelial calcification in diabetes mellitus, as revealed by parallel metabolic profiles.

BACKGROUND AND AIMS: Diabetic atherosclerotic vascular disease is characterized by extensive vascular calcification. However, an elevated blood glucose level alone does not explain this pathogenesis. We investigated the metabolic markers underlying diabetic atherosclerosis and whether extracellular Hsp90α (eHsp90α) triggers vascular endothelial calcification in this particular metabolic environment. METHODS: A parallel human/animal model metabolomics approach was used. We analyzed 40 serum samples collected from 24 patients with atherosclerosis and from the STZ-induced ApoE-/- mouse model. A multivariate statistical analysis of the data was performed, and mouse aortic tissue was collected for the assessment of plaque formation. In vitro, the effects of eHsp90α on endothelial cell calcification were assessed by serum analysis, Western blotting and immunoelectron microscopy. RESULTS: Diabetic ApoE-/- mice showed more severe plaque lesions and calcification damage. Stearamide, oleamide, l-thyroxine, l-homocitrulline and l-citrulline are biomarkers of diabetic ASVD; l-thyroxine was downregulated in both groups, and the thyroid sensitivity index was correlated with serum Hsp90α concentration. In vitro studies showed that eHsp90α increased Runx2 expression in endothelial cells through the LRP1 receptor. l-thyroxine reduced the increase in Runx2 levels caused by eHsp90α and affected the distribution and expression of LRP1 through hydrogen bonding with glutamine at position 1054 in the extracellular segment of LRP1. CONCLUSIONS: This study provides a mechanistic link between characteristic serum metabolites and diabetic atherosclerosis and thus offers new insight into the role of extracellular Hsp90α in promoting vascular calcification.

Relationship between social isolation and glycaemic control of people previously diagnosed with diabetes: secondary analysis from the CHARLS.

OBJECTIVES: Social isolation may affect diabetes self-management. This study aimed to explore the relations between social isolation and glycaemic control in patients with diabetes and to explore lifestyle differences among individuals with different levels of social isolation. METHODS: The relevant data of 665 people previously diagnosed with diabetes included in the China Health and Retirement Longitudinal Study from 2011 to 2015 were extracted and analysed. The study included patient general information, blood glucose, lipids, glycosylated haemoglobin, social isolation index, health-related lifestyle factors and diabetes-related factors. Differences in metabolic abnormalities and modifiable lifestyles were compared among patients with varying levels of social isolation. RESULTS: Multiple linear regression analysis demonstrated that among men aged 45-64 years, the high social isolation group had significantly higher glycosylated haemoglobin levels compared with the low isolation group (7.29±1.81 vs 6.59±1.63, p=0.026). A positive correlation was observed between social isolation and blood glucose (ß=14.16; 95% CI 2.75 to 25.57; p=0.015) and glycosylated haemoglobin (ß=0.35; 95% CI 0.10 to 0.60; p=0.006), indicating that higher social isolation was associated with higher fasting blood glucose and glycosylated haemoglobin levels. However, no significant associations were observed in other age groups. Notably, men aged 45-65 years with high social isolation had higher depression rates (44.10% vs 24.60%, p=0.024), lower engagement in moderate exercise (5.70% vs 23.50%, p=0.019) and shorter 10-minute walks (17.10% vs 36.80%, p=0.027). Differences in other health-related and diabetes-related factors were not statistically significant. CONCLUSION: Middle-aged men with diabetes with higher social isolation tend to have higher blood glucose and glycosylated haemoglobin levels. This subset of patients requires targeted attention to provide social support from family and friends for improved glycaemic control. If necessary, education on diabetes should be made available to family members and friends.

Gram-Negative Bacteria and Lipopolysaccharides as Risk Factors for the Occurrence of Diabetic Foot.

CONTEXT: Imbalance of the skin microbial community could impair skin immune homeostasis and thus trigger skin lesions. Dysbiosis of skin microbiome may be involved in the early pathogenesis of diabetic foot (DF). However, the potential mechanism remains unclear. OBJECTIVE: To investigate the dynamic composition and function of the foot skin microbiome with risk stratification for DF and assess whether dysbiosis of the skin microbiome induces diabetic skin lesions. METHODS: We enrolled 90 consecutive subjects who were divided into 5 groups based on DF risk stratification: very low, low, moderate, and high risk for ulcers and a healthy control group. Integrated analysis of 16S ribosomal RNA and metagenomic sequencing of cotton swab samples was applied to identify the foot skin microbiome composition and functions in subjects. Then a mouse model of microbiota transplantation was used to evaluate the effects of the skin microbiome on diabetic skin lesions. RESULTS: The results demonstrated that, with the progression of diabetic complications, the proportion of gram-negative bacteria in plantar skin increased. At the species level, metagenome sequencing analyses showed Moraxella osloensis to be a representative core strain in the high-risk group. The major microbial metabolites affecting diabetic skin lesions were increased amino acid metabolites, and antibiotic resistance genes in microorganisms were abundant. Skin microbiota from high-risk patients induced more inflammatory cell infiltration, similar to the lipopolysaccharide (LPS)-stimulated response, which was inhibited by Toll-like receptor 4 (TLR4) antagonists. CONCLUSIONS: The skin microbiome in patients with diabetes undergoes dynamic changes at taxonomic and functional levels with the progression of diabetic complications. The increase in gram-negative bacteria on the skin surface through LPS-TLR4 signal transduction could induce inflammatory response in early diabetic skin lesions.