Correlations of insulin resistance and HbA1c with cytokines IGF-1, bFGF and IL-6 in the aqueous humor of patients with diabetic cataract

Endothelin-1-mediated miR-let-7g-5p triggers interlukin-6 and TNF-α to cause myopathy and chronic adipose inflammation in elderly patients with diabetes mellitus

Background: Diabetes and sarcopenia are verified as mutual relationships, which seriously affect the quality of life of the elderly. Endothelin-1 is well investigated, is elevated in patients with diabetes, and is related to muscle cellular senescence and fibrosis. However, the mechanism of ET-1 between diabetes and myopathy is still unclear. The aim of this study was to evaluate the prevalence of sarcopenia in the elderly with diabetes and to clarify its relationship with ET-1 molecular biological mechanism, progress as well as changes in muscle and fat.

Methods: We recruited 157 type 2 diabetes patients over 55 years old and investigated the prevalence of sarcopenia in diabetes patients and examined the association of ET-1 alterations with HbA1c, creatinine, or AMS/ht2. Next, sought to determine how ET-1 regulates inflammation in muscle cells by western blot and qPCR assay. Using XF Seahorse Technology, we directly quantified mitochondrial bioenergetics in 3T3-L1 cells.

Results: ET-1 was positively correlated with HbA1c, creatinine levels, and duration of disease, and negatively correlated with AMS/ht2. We found that ET-1 dose-dependently induces tumor necrosis factor-α (TNF-α) and interleukin (IL)-6β expression through the PI3K/AKT, and NF-κB signaling pathways in C2C12 cells. Also identified that TNF-α, IL-6β, and visfatin releases were found in co-cultured with conditioned medium of ET-1/C2C12 in 3T3-L1 cells. ET-1 also reduces the energy metabolism of fat and induces micro-environment inflammation which causes myopathy. ET-1 also suppresses miR-let-7g-5p expression in myocytes and adipocytes.

Conclusion: We describe a new mechanism of ET-1 triggering chronic inflammation in patients with hyperglycemia.

MiR-29a Alleviates High Glucose-induced Inflammation and Mitochondrial Dysfunction via Modulation of IL-6/STAT3 in Diabetic Cataracts

Background: This in vitro study was designed to reveal the role of miR-29a in high glucose-induced cellular injury through the modulation of IL-6/STAT3 in diabetic cataracts.Methods: The expression of miR-29a and STAT3 in the lens capsules of patients with or without diabetes was determined by RT-PCR. The levels of the IL-6 proinflammatory cytokine in the aqueous humor were detected by ELISA. HLE B-3 cells were cultured in normal glucose (NG; 5 mM) or high glucose (HG; 40 mM). After transfection with miR-29a, si-STAT3, or a negative control vector, the levels of IL-6 and STAT3 were detected. A CCK-8 assay was used to determine cell viability. We used flow cytometry to assess changes in reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), and apoptosis induced by oxidative stress. Western blotting was used to determine the expression of the oxidative injury markers superoxide dismutase (SOD) and malondialdehyde (MDA) and the apoptosis markers Bcl-2 and Bax.Results: Reduced miR-29a, increased STAT3 expression, and IL-6 release were demonstrated in the lens capsules and aqueous humor of patients with diabetes. The stimulation of apoptosis and the loss of MMP induced by HG were attenuated by transfection with a miR-29a mimic and si-STAT3. ROS production, increased MDA content, decreased SOD activity, and upregulation of the apoptotic proteins Bcl-2/Bax were also partially alleviated by miR-29a overexpression, which shows their roles in oxidative injury. Furthermore, transfection with a STAT3 overexpression vector reversed the effects of miR-29a.Conclusions: In conclusion, miR-29a mitigated HG-induced oxidative injury and exerted protective effects via IL-6/STAT3 signaling. Thus, miR-29a may be a potential therapeutic agent for diabetic cataracts.

Concentrations of Selected Cytokines and Vascular Endothelial Growth Factor in Aqueous Humor and Serum of Diabetic Patients

Purpose: To investigate the aqueous humor and serum levels of selected cytokines and vascular endothelial growth factor (VEGF) in diabetic patients, implicating their role in the pathogenesis of diabetic eye complications.Materials and methods:   Atotal of 65 patients (27 males and 38 females) who underwent cataract surgery were recruited into the study. The study group consisted of 30 cataract patients with type 2 diabetes mellitus, and this group was divided into two subgroups: 14 patients with diabetic retinopathy (DR group) and 16 patients without DR (NDR group). The control group consisted of 35 non-diabetic cataract subjects.Results: Patients in the DR group had significantly higher aqueous humor concentrations of interleukin (IL)-1β, IL-6, IL-8, IL-10, monocyte chemotactic protein (MCP-1) and VEGF. Likewise, serum concentrations of IL-1β, IL-6, IL-8, IL-12, TNF-α and IFN-γ were significantly higher in the DR group as compared to the controls. Aqueous humor concentrations of IL-1β, IL-8, MCP-1 and VEGF were significantly higher in the DR group as compared with the NDR group.Conclusion: Our findings support the hypothesis that chronic inflammation and a disturbance of the immune system play important roles in the pathogenesis of diabetic cataract and DR.