Knockdown of ITIH4 reduces inflammatory damage and apoptosis of A549 cells induced by Mycoplasma pneumoniae through NLRP3 inflammation.

BACKGROUND

Mycoplasma pneumoniae (MP) is a leading cause of community-acquired respiratory infections in pediatric patients. This study aimed to investigate whether the pro-inflammatory function of inter-alpha-trypsin inhibitor heavy chain (ITIH4) contributes to the pathogenesis of MP-induced pneumonia.

METHOD: A549 cells were stimulated with MP to model pneumonia in vitro. ITIH4 expression was knocked down in A549 cells using lentiviral transfection. Cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay, while cell apoptosis was assessed via flow cytometry. The concentrations of pro-inflammatory (IL-6, TNF-α) and anti-inflammatory (IL-10) cytokines were quantified using enzyme-linked immunosorbent assay (ELISA). Western blotting was conducted to detect apoptosis-related proteins and components of the NLRP3 inflammasome.

RESULT: MP stimulation led to increased ITIH4 expression in A549 cells, and knockdown of ITIH4 prevented the MP-induced reduction in cell viability. Moreover, ITIH4 knockdown reduced the release of inflammatory cytokines in response to MP and significantly decreased MP-induced apoptosis. In addition, ITIH4 knockdown inhibited activation of the NLRP3 inflammasome, while reactivation of NLRP3 reversed the protective effects associated with ITIH4 knockdown.

CONCLUSION

ITIH4 knockdown alleviates MP-induced inflammatory damage and cell death in A549 cells by inhibiting activation of the NLRP3 inflammasome.