Effect of sulforaphane on Toll like receptor 4/nuclear factor-kappa B signaling pathway in rats with sepsis-induced acute lung injury

Abstract

Objective To evaluate the effects of sulforaphane on inflammatory reaction and Toll like receptor 4 (TLR4)/ nuclear factor-kappa B (NF-κB) signaling pathway in rats with sepsis-induced acute lung injury (ALI). Methods Thirty male Sprague Dawley rats were randomly divided into the sham operation group, model group and treatment group, with 10 rats in each group. Rats in the model group and treatment group were prepared by cecal ligation and puncture (CLP). Rats in the treatment group were intraperitoneally injected with 50 mg/kg sulforaphane immediately after operation, while the other two groups were injected with isosmotic NaCl solution. Arterial blood samples were collected from the right common carotid artery 24 hours after operation, and then lung tissues were taken from rats to determine their wet/dry ratio. The expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and NF-κB p65 in the lung tissue homogenate of rats in three groups were detected by enzyme-linked immunosorbent assay (ELISA), and TLR4 mRNA expressions were measured by real-time fluorescence quantitative PCR. Results The expression levels of lung tissue wet/dry ratio [(4.00 ± 0.13), (6.10 ± 0.05), (5.80 ± 0.08)], oxygenation index [(315 ± 11), (177 ± 7), (200 ± 12) mmHg], TNF-α [(6.05 ± 0.29), (45.06 ± 0.52), (27.09 ± 0.85) ng/L], IL-1β [(8.02 ± 0.21), (38.23 ± 0.81), (32.73 ± 1.12) ng/L] and NF-κB p65 [(0.375 ± 0.013), (1.230 ± 0.045), (0.988 ± 0.043) ng/L] were statistically significantly different in three groups (F = 480.891, 255.309, 4 245.262, 1 918.168, 564.842; all P < 0.001). Further comparison showed that the wet/dry ratio, TNF-α, IL-1β and NF-κB p65expressions of lung tissue in the model group and treatment group were all significantly higher than those in the sham operation group (all P < 0.05); in the same time, the wet/dry ratio, TNF-α, IL-1β and NF-κB p65 expressions in the treatment group were all significantly lower than those in the model group (all P < 0.05). The oxygenation index of rats in the model group and treatment group was significantly lower than that in the sham operation group (both P < 0.05), while the oxygenation index in the treatment group was significantly higher than that in the model group (P < 0.05). The results of real-time quantitative PCR showed that there was significant difference in the expression of TLR4 mRNA among these three groups (F = 224.538, P < 0.001). Compared with the sham operation group, the expression of TLR4 mRNA of lung tissue in the model group and treatment group were significantly higher (both P < 0.05), while the expression of TLR4 mRNA in the treatment group was significantly lower than that in the model group (P < 0.05). Conclusions Sulforaphane can reduce lung tissue inflammatoryreaction and pulmonary edema and improve anoxic state in rats with acute lung injury caused by sepsis. It has a protective effect on lung tissue, and its mechanism may be related to the intervention of TLR4/NF-κB signaling pathway. Key words: Sepsis; Acute lung injury; Toll like receptor 4; Sulforaphane; Inflammatory reaction; Nuclear factor-kappa B