Role of NEK7/NLRP3 signaling pathway in sepsis-associated encephalopathy in mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of NIMA-related kinase 7 (NEK7)/Nod-like receptor family pyrin domain-containing protein 3 (NLRP3) signaling pathway in sepsis-associated encephalopathy in mice.Methods:A total of 150 healthy adult male C57BL/6 mice, aged 8-12 weeks, weighing 20-25 g, were divided into 5 groups ( n=30 each) by a random number table method: sham operation group (Sham group), sepsis group (CLP group), sepsis+ NLRP3 inhibitor MCC950 group (CLP+ MCC950 group), sepsis+ NEK7 siRNA group (CLP+ NEK7 siRNA group), and sepsis+ NC siRNA group (CLP+ NC siRNA group). Sepsis was induced by classic cecal ligation and puncture (CLP) in anesthetized animals.MCC950 10 mg/kg was intraperitoneally injected for 3 consecutive days after operation in CLP+ MCC950 group, while the equal volume of normal saline was given instead in Sham group.Immediately after operation and on 3rd day after operation, NEK7 siRNA 3 nmol/20 g was injected into the ventricle in CLP+ NEK7 siRNA group, and the equal dose of NC siRNA was injected into the ventricle instead in Sham group.The survival of mice was recorded on 4th postoperative day.On 4th and 7th days after operation, 10 mice in each group were selected for Y maze space recognition experiment.On 7th day after operation, 5 mice in each group were randomly sacrificed and hippocampal tissues were taken for determination of the contents of interleukin-1beta (IL-1β), interleukin-18 (IL-18) and tumor necrosis factor-alpha (TNF-α) (by enzyme-linked immunosorbent assay), and 6 mice in each group were sacrificed and hippocampal tissues were taken for determination of the expression of NEK7, NLRP3, cleaved-caspase-1 and apoptosis-associated speck-like protein containing a caspase-1 recruitment domain (ASC) (by Western blot). Results:The survival rates were 100%, 50%, 73%, 60% and 53% in Sham, CLP, CLP+ MCC950, CLP+ NEK7 siRNA, and CLP+ NC siRNA groups, respectively, on day 4 after surgery.Compared with Sham group, the frequency of entries into novel arm was significantly reduced, and the time spent in the novel arm was shortened at 4th and 7th days after operation, and the contents of IL-1β, IL-18 and TNF-α in hippocampus were increased, and the expression of NEK7, NLRP3, cleaved-caspase-1 and ASC was up-regulated at 7th day after operation in CLP group ( P<0.05). Compared with CLP group, the frequency of entries into novel arm was significantly increased, and the time spent in the novel arm was prolonged at 4th and 7th days after operation, and the contents of IL-1β, IL-18 and TNF-α in hippocampus were decreased at 7th day after operation in CLP+ MCC950 and CLP+ NEK7 siRNA groups, the expression of NLRP3, cleaved-caspase-1 and ASC was significantly down-regulated at 7th day after operation in CLP+ MCC950 group, the expression of NEK7, NLRP3, cleaved-caspase-1 and ASC was significantly down-regulated in CLP+ NEK7 siRNA group ( P<0.05), and no significant change was found in the parameters mentioned above in CLP+ NC siRNA group ( P>0.05). Conclusions:NEK7/NLRP3 signaling pathway is involved in SAE in mice, and the underlying mechanism may be related to promotion of inflammatory responses.