ABSTRACT
Objective:To investigate the protective effect of β- blocker (esmolol) on myocardia and toll-like receptor 4 (TLR4) inflammatory pathway in septic rats.Methods:Sixty male Wistar rats were randomly (random number) divided into the shame group, sepsis group (CLP group), esmolol group (CLP+ES group) and TLR4 inhibitor group (CLP+TAK-242 group) with 15 rats in each group. Cecal exploration was performed in the shame group, and cecal ligation and perforation (CLP) was performed in the CLP group, CLP+ES group and CLP+TAK-242 group. The CLP+ES group received intraperitoneal injection of esmolol diluent 20 mg/kg 12 h after CLP. The CLP+TAK-242 group was given intraperitoneal injection of TAK-242 3 mg/kg at the same time point as above. The shame group and CLP group were given the same amount of normal saline. Rats in all groups were sacrificed 24 h after operation, and the samples were collected and processed. The pathological changes of myocardium were observed by hematoxylin - eosin staining. The expression of TLR4, myeloid differentiation protein 88 (MyD88) and nuclear factor -κB (NF-κB) in myocardial tissue were observed by immunohistochemistry. Masson staining was used to observe the expression of fibers and inflammatory factors in myocardial tissue. The protein expressions of TLR4, MyD88, NF-κB and aspartic acid specific cysteine protease 1 (caspase-1) were detected by Western blot. Serum levels of cardiac troponin I (cTn-I), tumor necrosis factor α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were detected by enzyme-linked immunosorbent assay (ELISA).Results:Compared with the shame group, myocardial injury, fibrosis and inflammatory cell infiltration were significantly aggravated in the CLP group, and the levels of myocardial injury index cTn-I and inflammatory mediators TNF-α, IL-6 and IL-1β were significantly increased [(8.70±0.22) vs. (4.41±0.31), (445.57±9.13) vs. (219.60±5.52), (165.55±2.18) vs. (93.47±3.37), (124.12±2.59) vs. (67.63±6.04),all P<0.05]. Compared with the CLP group, myocardial injury was significantly reduced in the CLP+ES group and CLP+TAK-242 group, and the levels of inflammatory transmitters were significantly reduced [(5.38±0.18) and (5.37±0.13) vs. (8.70±0.22), (322.73±7.63) and (300.58±17.47) vs. (445.57±9.13), (121.28±5.44) and (120.30±4.95) vs. (165.55±2.18), (102.60±4.09) and (105.08±7.21) vs. (124.12±2.59), all P<0.05]. Western blot analysis showed that the protein expression levels of TLR4, MyD88, NF-κB and caspase-1 in the CLP group were significantly higher than those in the shame group [(1.79±0.15) vs. (1.15±0.04), (4.70±0.30) vs. (3.87±0.10), (0.35±0.04) vs. (0.18±0.02), (2.27±0.29) vs. (1.15±0.07), all P<0.05], while the protein expression levels in the CLP+ES group and CLP+TAK-242 group were significantly lower than those in the CLP group [(1.31±0.16) and (1.18±0.14) vs. (1.79±0.15), (1.50±0.16) and (1.46±0.19) vs. (2.27±0.29), (0.27±0.02) and (0.24±0.01) vs. (0.35±0.04), (1.50±0.16) and (1.46±0.19) vs. (2.27±0.29), all P<0.05]. Conclusions:β-blocker can reduce myocardial injury and inhibit the expression of inflammatory mediators in septic rats by blocking the inflammatory response mediated by TLR4 signaling pathway.
ABSTRACT
OBJECTIVE@#To evaluate the protective effect of excretory-secretory proteins from Trichinella spiralis muscle larvae (Ts-MES) on sepsis-induced myocardial injury in mice.@*METHODS@#Eighty male BALB/C mice were randomized equally into sham-operated group, myocardial injury group, Ts-MES treatment group and dexamethasone treatment group. In the latter 3 groups, sepsis-induced myocardial injury models were established by cecal ligation and perforation; the sham operation was performed by exposure of the cecum without ligation or perforation. Forty minutes after the operation, the mice were given intraperitoneal injections 150 μL PBS, 20 μg TS-MES or 0.3 mg/kg dexamethasone as indicated. At 12 h after the operation, 6 mice were randomly selected from each group for echocardiography, and 8 mice were used for observing the survival rate within 72 h. The remaining 6 mice were examined for myocardial pathologies with HE staining and serum levels of NTPro-BNP and cTnI with ELISA; the expressions of TNF-α, IL-6, IL-10 and TGF-β in the serum and myocardial tissue were detected using ELISA and qRT-PCR.@*RESULTS@#Compared with the sham-operated mice, the septic mice showed significantly decreased cardiac function indexes (LVEF, LVFS, and E/A) with lowered survival rate within 72 h (P < 0.001) and significantly higher myocardial injury scores and serum levels of NTPro-BNP and cTnI (P < 0.01). Treatment with TS-MES significantly improved the cardiac function and 72-h survival rate (P < 0.05) and lowered the myocardial injury scores and serum levels of NTPro-BNP and cTnI (P < 0.05) in the septic mice. Compared with the sham-operated mice, the septic mice had obviously increased TNF-α and IL-6 levels in the serum and myocardial tissue (P < 0.001), which were significantly lowered by treatment with TS-MES (P < 0.05). TS-MES and dexamethasone both increased the levels of IL-10 and TGF-β in the septic mice, but the changes were significant only in TS-MES-treated mice (P < 0.05).@*CONCLUSION@#Ts-MES are capable of protecting against myocardial injury in septic mice by reducing the production of pro-inflammatory cytokines and enhancing the levels of regulatory cytokines.