Tanshinone IIA alleviates lipopolysaccharide-induced acute lung injury by downregulating TRPM7 and pro-inflammatory factors

Abstract

The study aimed to investigate the role of Tanshinone IIA (Tan IIA) in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in its regulation of TRPM7. Wistar male rats were randomly divided into the normal saline (NS), LPS, knockout (KO) + LPS, low-dose Tan IIA (Tan-L), middle-dose Tan IIA (Tan-M), high-dose Tan IIA (Tan-H) and KO + high-dose Tan IIA (KO + Tan-H) groups. The level of tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, TRPM7 protein expression, current density-voltage curve and Ca²⁺ concentration were detected through ELISA, Western blotting, electrophysiological experiment and a calcium-imaging technique, respectively. The rats in the KO + LPS, Tan-L, Tan-M, Tan-H and KO + Tan-H groups all displayed lower levels of TNF-α, IL-1β and IL-6 than the LPS group. Rats in the KO + Tan-H group exhibited lower levels of NF-α, IL-1β and IL-6 than rats in the Tan-H group. Elevated levels of TRPM7 protein expression in the LPS and Tan groups were detected in comparison with the NS group. However, TRPM7 protein expression in Tan-M and Tan-H groups was notably lower than in that of the LPS group. In comparison with the NS group, the LPS and Tan groups had a greater PIMs cell density and a higher concentration of Ca²⁺ . Contrary results were observed in the KO + LPS, Tan-H and KO + Tan-H groups. Tan IIA decreases calcium influx in PIMs and inhibits pro-inflammatory factors which provide an alleviatory effect in regards to LPS-induced ALI by suppressing TRPM7 expression.

Keywords: Tanshinone IIA; acute lung injury; interleukin 6; lipopolysaccharide; transient receptor potential melastatin 7; tumour necrosis factor alpha.

Figure 1

Pathological changes of right lung tissue detected by HE staining under light microscope among seven groups (×100). HE: haematoxylin and eosin; NS: normal saline; LPS: lipopolysaccharide; Tan A (L): low‐dose Tanshinone IIA; Tan A (M): middle‐dose Tanshinone IIA; Tan A (H): high‐dose Tanshinone IIA; KO: knockout.

Figure 2

Levels of TNF‐α, IL‐1β and IL‐6 detected by ELISA among seven groups. A–C, Changes of TNF‐α, IL‐1β and IL‐6 levels in lung tissues; D–F, Changes of TNF‐α, IL‐1β and IL‐6 levels in BALF; *P < 0.05, compared with the NS group; ^# P < 0.05, compared with the LPS group; ^& P < 0.05, compared with the 6th day; ELISA: enzyme‐linked immunosorbent assay; NS: normal saline; LPS: lipopolysaccharide; Tan A (L): low‐dose Tanshinone IIA; Tan A (M): middle‐dose Tanshinone IIA; Tan A (H): high‐dose Tanshinone IIA; TNF‐α: tumour necrosis factor‐α; IL‐1β, interleukin‐1 beta; IL‐6: interleukin‐6; KO: knockout; BALF: bronchoalveolar lavage fluid.

Figure 3

Comparisons of TRPM7 protein expressions in the PIMs among seven groups. B and of TRPM7 protein for each group; B, TRPM7 protein expressions for each group; *P < 0.05, compared with the NS group; ^# P < 0.05, compared with the LPS group; NS: normal saline; LPS: lipopolysaccharide; Tan A (L): low‐dose Tanshinone IIA; Tan A (M): middle‐dose Tanshinone IIA; Tan A (H): high‐dose Tanshinone IIA; KO: knockout.

Figure 4

Staining of serosa of PIMs detected by DAB staining among five groups (×200). PIMs: pulmonary interstitial macrophages; DAB: diaminobenzidine; NS: normal saline; LPS: lipopolysaccharide; Tan A (H): high‐dose Tanshinone IIA; KO: knockout.

Figure 5

TRPM7L current changes on the PIMs of rats among five groups. PIMS: pulmonary interstitial macrophages; NS: normal saline; LPS: lipopolysaccharide; Tan A (H): high‐dose Tanshinone IIA; KO: knockout.

Figure 6

Ca^{2 +} concentration changes in PIMs of rats among five groups. PIMs: pulmonary interstitial macrophages; NS: normal saline; LPS: lipopolysaccharide; Tan A (H): high‐dose Tanshinone IIA; KO: knockout.