Effect of hydrogen on expression of matrix metalloproteinase-9 in brain tissues of mice with sepsis-associated encephalopathy

Abstract

Objective To evaluate the effect of hydrogen on the expression of matrix metalloproteinase-9 (MMP-9) in brain tissues of mice with sepsis-associated encephalopathy (SAE). Methods A total of 212 clean-grade healthy male C57BL/6J mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups (n=53 each) using a random number table method: sham operation group (group Sham), sham operation plus hydrogen group (group Sham+ H2), group SAE and SAE plus hydrogen group (group SAE+ H2). The sepsis model was established by intraperitoneally injecting human fecal suspension.Sham+ H2 and SAE+ H2 groups inhaled 2% hydrogen for 1 h at 1 and 6 h after establishing the model, respectively.Postoperative 14-day survival rate was recorded.Evans blue (EB) was injected into the tail vein at 24 h after establishing the model, and the content of EB in brain tissues was calculated.Brain tissues were taken for determination of brain water content.The expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and high-mobility group box 1 protein (HMGB1) in hippocampal tissues was detected by enzyme-linked immunosorbent assay.The expression of MMP-9 and ZO-1 protein and mRNA in hippocampal tissues was determined by Western blot and real-time polymerase chain reaction, respectively, at 6, 12 and 24 h after establishing the model. Results Compared with Sham group, the 14-day survival rate was significantly decreased, the EB content in brain tissues, brain water content, and contents of TNF-α, IL-6 and HMGB1 were significantly increased, the expression of MMP-9 protein and mRNA was up-regulated, and the expression of ZO-1 protein and mRNA was down-regulated in SAE and SAE+ H2 groups (P 0.05). Compared with group SAE, the 14-day survival rate was significantly increased, the EB content in brain tissues, brain water content, and contents of TNF-α, IL-6 and HMGB1 were significantly decreased, the expression of MMP-9 protein and mRNA was down-regulated, and the expression of ZO-1 protein and mRNA was up-regulated in group SAE+ H2 (P<0.05). Conclusion The mechanism by which hydrogen attenuates the blood-brain barrier damage may be related to inhibiting MMP-9 expression and to reducing inflammatory responses in brain tissues of SAE mice. Key words: Hydrogen; Sepsis; Bood-brain barrier; Matrix metalloproteinase 9