The role of HMGB1/RAGE/TLR4 signaling pathways in cigarette smoke-induced inflammation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease with irreversible and continuous progression. It has become the fifth most burdensome disease and the third most deadly disease globally. Therefore, the prevention and treatment of COPD are urgent, and it is also important to clarify the pathogenesis of it. Smoking is the main and most common risk factor for COPD. Cigarette smoke (CS) can cause lung inflammation and other pathological mechanisms in the airways and lung tissue. Airway inflammation is one of the important mechanisms leading to the pathogenesis of COPD. Recent studies have shown that high mobility group box 1 (HMGB1) is involved in the occurrence and development of respiratory diseases, including COPD. HMGB1 is a typical damage-associated molecular pattern (DAMP) protein, which mainly exerts its activity by binding to the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4) and further participate in the process of airway inflammation. Studies have shown that the abnormal expression of HMGB1, RAGE, and TLR4 are related to inflammation in COPD. Herein, we discuss the roles of HMGB1, RAGE, and TLR4 in CS/cigarette smoke extract-induced inflammation in COPD, providing a new target for the diagnosis, treatment and prevention of COPD.

Long non-coding RNA H19 contributes to spinal cord ischemia/reperfusion injury through increasing neuronal pyroptosis by miR-181a-5p/HMGB1 axis

Pyroptosis, a programmed inflammatory necrotizing cell death, is likely involved in spinal cord ischemia-reperfusion (SCI/R) injury, but the mechanisms initiating driving neuronal pyroptosis must be further revealed. The aim of this study is to unravel the mechanism of long non-coding RNA (lncRNA) H19 during SCI/R. SCI/R model was induced in C57BL/6 mice by blocking the aortic arch in vivo, and oxygen-glucose deprivation/reperfusion (OGD/R) injury model of PC12 cells was established in vitro. Our results showed that H19 and HMGB1 expression was upregulated, while miR-181a-5p was downregulated in the SCI/R mice and OGD/R-treated PC12 cells. SCI/R induced pathological damage, pyroptosis and inflammation compared with the sham group. H19 acted as a molecular sponge to suppress miR-181a-5p, and HMGB1 was identified as a direct target of miR-181a-5p. MiR-181a-5p overexpression inhibited the increase of IL-1β, IL-18 and TNF-α production and NLRP3, ASC, and Cleaved-caspase-1 expression in OGD/R-treated PC12 cells; while miR-181a-5p silencing exerted opposite effects. HMGB1 overexpression reversed H19 knockdown-mediated the inhibition of pyroptosis and inflammation in OGD/R-treated PC12 cells. In vivo, H19 knockdown promoted the hind limb motor function recovery and alleviated the pathological damage, pyroptosis and inflammation induced by SCI/R. LncRNA H19/miR-181a-5p/HMGB1 pathway contributes to pyroptosis via activating caspase1 signaling during SCI/R, suggesting that this axis may be a potent therapeutic target in SCI/R.