Lactoferrin improved radioactive lung damage by regulating HMGB1/TLR4 inflammation / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the protective effect of lactoferrin(Lf) on lung injury in mice exposed to irradiation.Methods:C57BL/6 J mice were randomly divided into control group, 15 Gy irradiation group (IR group) and lactoferrin combined 15 Gy irradiation group (Lf+ IR group), with 5 mice in each group. The mice in the Lf+ 15 Gy group drank lactoferrin solution (10 mg/ml) from 3 days before irradiation and contained the whole experiments. Then, single chest 15 Gyirradiation was performed both in the IR and Lf+ IR groups. The body weight and other characteristics were monitored during the experiment. The mice were killed at day 14 after irradiation. The lung histopathology was observed by HE staining. Serum inflammatory cytokine such as HMGB1, TNF-α, IL-1β and IL-6 was determined by ELISA method . The expression of inflammatory related protein in lung tissue including HMGB1, TLR4, MyD88 and NF-κB were performed by immune histochemistry and Western blot method.Results:Compared with the control group, lung weight was significantly increased ( t=3.20, P<0.05), pulmonary hyperemia and inflammatory cell infiltration was observed in the IR group. Exposure also significantly increased serum level of TNF-α[(291.80±5.49) vs.(332.25±22.18)pg/ml]( t=3.07, P<0.05), up-regulated the expression of inflammatory related protein in lung tissue ( t=4.04, 4.78, 3.77, 6.14, P<0.05). Lactoferrin intervention (Lf+ IR group) significantly decreased lung weight ( t=2.18, P<0.05), alleviated histopathologic changes, decrease serum levels of HMGB1, TNF-α and IL-1β ( t=4.67, 2.97, 3.49, P<0.05). On the other hand, lactoferrin intervention decreased the positive cell number of HMGB1 and NF-κB, and down-regulated the protein expression of HMGB1, TLR4, MyD88 and NF-κB in lung tissues, with significant difference with the IR group ( t=8.06, 9.80, 3.07, 5.56, P<0.05). Conclusions:Lactoferrin plays the protective effect of radiation-induced lung injury through the downregulation of inflammatory response, such as HMGB1/TLR4/MyD88/NF-κB signaling pathway.