Objective To investigate the effect of mild hypothermia on neurological function in rats with spinal cord injury (SCI) based on the adenosine monophosphate activated protein kinase (AMPK)/Nod-like receptor protein 3 (NLRP3) pathway. MethodsFifty 7-8 weeks old SPF male Sprague Dawley rats were used to establish rat model of SCI by Allen’s method. Among them, 48 successfully modeled rats were randomly divided into SCI group, mild hypothermia group (SCI+mild hypothermia treatment), and Compound C group (SCI+mild hypothermia+20 mg/kg AMPK/NLRP3 pathway inhibitor Compound C), with 16 rats in each group; another 16 normal rats with laminectomy were selected as sham-operation group. Basso-Beattie-Bresnahan (BBB) score was used to evaluate the motor ability of rats at 1, 3, 7, 14 days after treatment. After 14 days, the rats were sacrificed, and the spinal cord histopathological morphology was observed by HE staining, the neuronal apoptosis in spinal cord tissue was detected by TUNEL assay, and the serum levels of interleukin 2 (IL-2), IL-6, transforming growth factor β1 (TGF-β1), malondialdehyde (MDA), and superoxide dismutase (SOD) were detected by ELISA. The expression of AMPK/NLRP3 pathway protein, including B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and cleaved-Caspase-9 were detected by Western blot. Results At 1 day after treatment, the rats in SCI group, mild hypothermia group, and Compound C group did not recover their motor ability; at 3, 7, and 14 days, the BBB score of SCI group was significantly lower than that of SCI group (P<0.05), the BBB score of mild hypothermia group was significantly higher than that of SCI group (P<0.05), and the BBB score of Compound C group was significantly lower than that of mild hypothermia group (P<0.05). Compared with the sham-operation group, the SCI group displayed obvious pathological changes in the spinal cord tissue, with disordered tissue architecture, inflammatory infiltration, and blurred interstitial boundaries. The neuronal apoptosis rate, Bax/Bcl-2 ratio, cleaved Caspase-9 expression, NLRP3 protein expression, serum IL-2, IL-6, and MDA levels were elevated, whereas serum TGF-β1, SOD levels, and spinal cord phosphorylation AMPK/AMPK protein expression significantly decreased (P<0.05). Compared with the SCI group, the above phenomena significantly improved in the mild hypothermia group (P<0.05), while the Compound C group showed the opposite trend of change compared to the mild hypothermia group (P<0.05). Conclusion Mild hypothermia can attenuate neurological dysfunction after SCI in rats, potentially by activating the AMPK/NLRP3 pathway.
Objective To investigate the effect of microRNA-22-3p (miR-22-3p) on the inflammation of human pulmonary microvascular endothelial cells (HPMEC) induced by lipopolysaccharide (LPS) by regulating the HMGB1/NLRP3 pathway. Methods miRNA microarray was taken from peripheral blood of patients with acute respiratory distress syndrome (ARDS) caused by abdominal infection and healthy controls for analysis, and the target miRNA was selected. miRNA mimics, inhibitor and their negative controls were transfected in HPMECs which were stimulated with LPS. Real time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect the mRNA and protein levels of high mobility group box-1 protein (HMGB1) and nucleotide binding oligomerization segment like receptor family 3 (NLRP3). RT-qPCR and enzyme linked immunosorbent assay were used to detect the levels of inflammatory factors in the cells and supernatant. Results miRNA microarray showed that miR-22-3p was down-regulated in the plasma of patients with ARDS. Compared with the negative control group, after miR-22-3p over-expression, the protein and mRNA levels of HMGB1 and NLRP3 decreased significantly. Similarly, the level of cleaved-caspase-1 decreased significantly. At the same time, interleukin (IL)-6, IL-8 and IL-1β mRNA level in cytoplasm and supernatant were down-regulated by miR-22-3p mimics. After transfected with miR-22-3p inhibitor, the expression levels of HMGB1, NLRP3, caspase-1 protein and inflammatory factors were significantly up-regulated. Conclusion miR-22-3p is significantly downregulated in peripheral blood of ARDS patients caused by abdominal infection, which can inhibit the expression of HMGB1 and NLRP3 and its downstream inflammatory response in HPMECs.