Effect of low-dose ethanol on NLRP3 inflammasome in diabetes-induced lung injury

To observe the changes in NLR family pyrin domain containing 3 (NLRP3) inflammasome in a rat model of diabetes-induced lung injury, and investigate the effect of low-dose ethanol on the production of NLRP3 inflammasome. The type I diabetic mellitus (DM) rat model was established, and the rats were divided into four groups: normal control group (CON group), low-dose ethanol group (EtOH group), diabetes group (DM group) and DM+EtOH group. The rats were fed for 6 and 12 weeks, respectively. The ratio of lung wet weight/body weight (lung/body coefficient) was calculated, and the changes of pulmonary morphology and fibrosis were observed by HE and Masson staining. The changes in pulmonary ultra-structure were examined by electron microscopy. The expressions of mitochondrial acetaldehyde dehydrogenase 2 (ALDH2) and NLRP3 inflammasome key factors, NLRP3, ASC and caspase-1 proteins were detected by western blot. Compared with the CON group, the lung/body coefficient was increased (P<0.05), lung fibrosis occurred, ALDH2 protein expression was decreased, and NLRP3, ASC and caspase-1 protein expressions were increased in the DM rats (P<0.05). Compared with the DM group, the lung/body coefficient and fibrosis degree were decreased, ALDH2 protein expression was increased (P<0.05), and NLRP3, ASC and caspase-1 protein expressions were decreased in the DM+EtOH group (P<0.05). Hence, low-dose ethanol increased ALDH2 protein expression and alleviated diabetes-induced lung injury by inhibiting the production of NLRP3 inflammasome.

Low-Dose Ethanol Has Impacts on Plasma Levels of Metabolites Relating to Chronic Disease Risk in SAMP8 mice

The effects of low-dose alcohol on experimental animals are unclear. This study examined plasma metabolites in senescence-accelerated mice 8 (SAMP8) given low-dose ethanol, and compared them with aging progress and skeletal muscle strength. Male SAMP8 mice (10-wk-old) were given drinking water containing 0% (control), 1%, 2%, or 5% (v/v) ethanol for 14 wk. Compared with the control group, only mice who consumed 1% ethanol experienced a lower senescence score at 18 and 23 wk, as well as an increased limb grip strength at 21 wk. Plasma metabolites of control, 1% and 2% ethanol groups were analyzed by capillary electrophoresis-time-of-flight mass spectrometry (CE-TOF/MS). Among the 7 metabolites affected by ethanol, notewhorthy is the positive association of the ethanol levels in drinking water with the levels of α-ketoglutarate (antioxidant and anti-inflammatory metabolite) and hippurate (antioxidant and microbial co-metabolite) (p<0.05). Intriguingly, the levels of 2-hydroxyisobutyrate (the biomarker of energy metabolism and microbial co-metabolite) were higher in the 1% ethanol group (p<0.05), but not in the 2% ethanol group as compared to the control. Furthermore, the levels of some of the metabolites affected were correlated with some variables in the grading score of senescence and muscle strength. This study provides a novel insight into how low-dose ethanol in SAMP8 mice modulates the levels of circulating metabolites relating to chronic disease risk.

[Effect of low-dose ethanol consumption on expression of nuclear factor-κB in diabetic rats with myocardial injury]

OBJECTIVE

To investigate the effect of low-dose ethanol on the expression of nuclear factor-κB (NF-κB) in diabetic rats with myocardial injury.

METHODS

Rat models of diabetes were established by an intraperitoneal injection of 55 mg/kg streptozotocin (STZ). After successful modeling, the rats were given 2.5% ethanol (daily dose of 20 mg/kg) for 1 week, followed by 5% ethanol (daily dose of 39.45 mg/kg) for another 7 weeks. Normal rats without STZ injection and diabetic rats without ethanol treatment serve as the normal control and diabetic model groups, respectively. The ventricular function of the rats was determined using echocardiography. The plasma levels of interleukin-1 (IL-1) and IL-4 were detected in the rats, and the expressions of 4-HNE, NF-κB and IKK proteins in the left anterior myocardium was evaluated using immunohistochemistry or Western blotting; the ultrastructural changes of the myocardium were observed using transmission electron microscopy.

RESULTS

Compared with the normal control group, the diabetic rats showed significantly lowered systolic and diastolic functions of the left ventricle, increased plasma level of IL-1 and myocardial 4-HNE expression (P &lt; 0.01), decreased plasma level of plasma IL-4 (P &lt; 0.01), and increased myocardial expressions of NF-κB and IKK proteins (P &lt; 0.01). Transmission electron microscopy revealed myofibrillar rupture, incomplete myofibrillar structure and mitochondrial damage in the cardiac myocytes in the diabetic rats. Compared with the diabetic rats, the rats with low-dose ethanol treatment exhibited improved systolic and diastolic functions of the left ventricle, milder myocardial myofibrillar and mitochondrial damages, and significantly lowered plasma IL-1 level and myocardial expressions of 4-HNE, NF-κB and IKK (P &lt; 0.01), and increased plasma IL-4 level (P &lt; 0.01).

CONCLUSIONS

NF-κB expression is increased in the myocardium of diabetic rats with myocardial injury, and low-dose ethanol consumption lowers myocardial expression of NF-κB in diabetic rats, suggesting the involvement of NF-κB signaling pathway in the protective effect of low-dose ethanol against myocardial injury in diabetes mellitus.