[Protective effect and mechanism of hyperbaric oxygen therapy on non-alcoholic fatty liver disease in mice]

Objective: To investigate the curative effect and mechanism of hyperbaric oxygen therapy on nonalcoholic fatty liver disease in mice. Methods: Twenty-one 8-week-old male C57BL/6J mice were divided into three groups: control group (normal diet), model group (high-fat and high-cholesterol diet), and hyperbaric oxygen group (high-fat and high-cholesterol diet + hyperbaric oxygen therapy), with seven mice in each group. The changes in body weight, serum liver enzymes, and blood lipids were compared after treatment between the three groups. Hematoxylin-eosin staining, Oil Red O staining, Sirius red staining, and F4/80 immunohistochemical staining were used to observe the pathological changes in liver tissues. RT-qPCR and Western blot methods were used to detect the expression levels of oxidative stress and inflammatory factors. One-way analysis of variance was used for comparison among the groups. Results: Mice in the hyperbaric oxygen group had significantly improved liver histopathology. The serological levels of alanine aminotransferase, aspartate aminotransferase, and cholesterol were (77.50±13.59) U/L, (156.06±23.68) U/L, and (4.80±0.53) mmol/L, which were significantly lower than those in the model group [(109.43±16.88) U/L, (216.62±18.79) U/L, and (5.86±0.53) mmol/L, P<0.05], and accompanied by lower levels of lipid deposition, macrophage infiltration, and fibrosis. In addition, compared with the model group, the expression of antioxidant stress protein nuclear transcription factor erythroid 2-related factor 2 [(0.30±0.06) and (2.16±1.21), P<0.05] and heme oxygenase-1 [(0.48±0.19) and (1.01±0.18), P<0.05] in liver tissue showed an upward trend following hyperbaric oxygen treatment, which was also validated at the transcriptional level (P<0.05). Simultaneously, compared with the model group, the mRNA expressions of tumor necrosis factor-α [(2.60±0.71) and (0.66±0.15), P<0.05], interleukin-1β [(2.41±1.01) and (0.78±0.23), P<0.05], and interleukin-6 [(3.61±2.17) and (0.94±0.25), P<0.05] in the liver tissue of mice in the hyperbaric oxygen group were decreased. The tumor necrosis factor-α protein level [(7.50±4.73) and (1.05±0.58), P<0.05] and interleukin-1β [(1.65±0.35) and (1.02±0.02), P<0.05] was reduced following hyperbaric oxygen treatment compared with those in the model group. Conclusion: Hyperbaric oxygen therapy can slow down the progression of nonalcoholic fatty liver disease by regulating the levels of oxidative stress and inflammation in the mice.