Baicalein attenuates bleomycin-induced lung fibroblast senescence and lung fibrosis through restoration of Sirt3 expression.

CONTEXT: Fibroblast senescence was reported to contribute to the pathological development of idiopathic pulmonary fibrosis (IPF), and baicalein is reported to attenuate IPF. OBJECTIVE: This study explores whether baicalein attenuates lung fibrosis by regulating lung fibroblast senescence. MATERIALS AND METHODS: Institute of Cancer Research (ICR) mice were randomly assigned to control, bleomycin (BLM), baicalein and BLM + baicalein groups. Lung fibrosis was established by a single intratracheal dose of BLM (3 mg/kg). The baicalein group received baicalein orally (100 mg/kg/day). Sirtuin 3 (Sirt3) siRNA (50 µg) was injected through the tail vein once a week for 2 weeks to explore its effect on the anti-pulmonary fibrosis of baicalein. RESULTS: BLM-treated mice exhibited obvious lung fibrosis and fibroblast senescence by showing increased levels of collagen deposition (27.29% vs. 4.14%), hydroxyproline (208.05 vs. 40.16 ng/mg), collagen I (25.18 vs. 9.15 µg/mg), p53, p21, p16, MCP-1, PAI-1, TNF-α, MMP-10 and MMP-12 in lung tissues, which were attenuated by baicalein. Baicalein also mitigated BLM-mediated activation of TGF-ß1/Smad signalling pathway. Baicalein restored the BLM-induced downregulation of Sirt3 expression in lung tissues and silencing of Sirt3 abolished the inhibitory role of baicalein against BLM-induced lung fibrosis, fibroblast senescence and activation of TGF-ß1/Smad signalling pathway. CONCLUSIONS: Baicalein preserved the BLM-induced downregulation of lung Sirt3 expression, and thus the suppression of TGF-ß1/Smad signalling pathway and lung fibrosis, which might provide an experimental basis for treatment of IPF.

Polyinosine-polycytidylic acid promotes excessive iodine intake induced thyroiditis in non-obese diabetic mice via Toll-like receptor 3 mediated inflammation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Excessive iodine intake and viral infection are recognized as both critical factors associated with autoimmune thyroid diseases. Toll-like receptors (TLRs) have been reported to play an important role in autoimmune and inflammatory disorders. In this study, we aimed to clarify the possible mechanism of TLR3 involved in polyinosine-polycytidylic acid (poly(I:C)) promoting excessive iodine intake induced thyroiditis in non-obese diabetic (NOD) mice.</p><p><b>METHODS</b>Both NOD and BALB/c mice were randomly assigned to four groups: control group (n = 5), high iodine intake (HI) group (n = 7), poly(I:C) group (n = 7) and combination of excessive iodine and poly(I:C) injection (HIP) group (n = 7). After 8 weeks, mice were weighed and blood samples were collected. All the mice were sacrificed before dissection of spleen and thyroid gland. Then, thyroid histology, thyroid secreted hormone, expression of CD3(+) cells and TLR3 as well as inflammatory mRNA level were evaluated.</p><p><b>RESULTS</b>Both NOD and BALB/c mice from HI and HIP group represented goiter and increasing thyroid relative weight. Thyroid histology evidence indicated that only HIP group of NOD mice showed severe thyroiditis with lymphocytes infiltration in majority of thyroid tissue, severe damage of follicles and general fibrosis. Immunofluorescence staining results displayed a large number of CD3(+) cells in HIP NOD mice. Real-time polymerase chain reaction (PCR) results suggested interferon (IFN)-α increased over 30 folds and IFN-γ expression was doubled compared with control group, but interleukin (IL)-4 remained unchanged in HIP group of NOD mice thyroid. Meanwhile, over one third decrease of blood total thyroxine (TT4) and increased thyroid-stimulating hormone (TSH) was observed in HIP group of NOD mice. Only HIP group of NOD mice represented significantly elevation of TLR3 expression.</p><p><b>CONCLUSION</b>Poly(I:C) enhanced excessive dietary iodine induced thyroiditis in NOD mice through increasing TLR3 mediated inflammation.</p>