TLR4-HMGB1 signaling pathway affects the inflammatory reaction of autoimmune myositis by regulating MHC-I.
OBJECTIVE
To analyze the effects of TLR4 on the expression of the HMGB1, MHC-I and downstream cytokines IL-6 and TNF-α, and to investigate the biological role of the TLR4-HMGB1 signaling pathway in the development of the autoimmune myositis.


METHODS
We built mice models with experimental autoimmune myositis (EAM) and used the inverted screen experiment to measure their muscle endurance; we also examined inflammatory infiltration of muscle tissues after HE staining; and we assessed the expression of MHC-I using immunohistochemistry. In addition, peripheral blood mononuclear cells (PBMC) were extracted and flow cytometry was utilized to detect the effect of IFN-γ on the expression of MHC-I. Furthermore, PBMCs were treated with IFN-γ, anti-TLR4, anti-HMGB1 and anti-MHC-I. Real-time PCR and western blotting were employed to examine the expressions of TLR4, HMGB1 and MHC-I in different groups. The ELISA method was also utilized to detect the expression of the downstream cytokines TNF-α and IL-6.


RESULTS
The expressions of TLR4, HMGB1 and MHC-I in muscle tissues from mice with EAM were significantly higher than those in the control group (all P<0.05). After IFN-γ treatment, the expressions of TLR4, HMGB1, MHC-I, TNF-α and IL-6 in PBMCs significantly increased (all P<0.05). The treatment of anti-TLR4, anti-HMGB1 and anti-MHC-I could significantly downregulate the expression of MHC-I (all P<0.05). In addition, anti-TLR4 and anti-HMGB1 significantly reduced the expression of TNF-α and IL-6 (all P<0.05).


CONCLUSIONS
The TLR4-HMGB1 signaling pathway affects the process of autoimmune myositis inflammation by regulating the expression of MHC-I and other pro-inflammatory cytokines.
Department of Clinical Laboratory, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China. Electronic address: 13760673961@163.com.
Zemin
Z
Wan
Department of Liver Disease, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China.
Xiujuan
X
Zhang
Department of Clinical Laboratory, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China.
Anping
A
Peng
Department of Clinical Laboratory, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China.
Min
M
He
Department of Urology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China.
Zhenhua
Z
Lei
Department of Clinical Laboratory, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, Guangdong, China.
Yunxiu
Y
Wang
D000818:Animals; D001327:Autoimmune Diseases / Q000378:metabolism*; D005260:Female; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism; D009220:Myositis / Q000378:metabolism*; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D024243:HMGB1 Protein; C582808:HMGB1 protein, mouse; D015395:Histocompatibility Antigens Class I; D015850:Interleukin-6; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; C577686:interleukin-6, mouse
Autoimmune myositis; MHC-I; Proinflammatory cytokines; TLR4-HMGB1 signaling pathway