Effect of an oropharyngeal streptococcal strain E-24 on inflammatory cytokines induced by Pseudomonas aeruginosa in human respiratory epithelial cells
Objective To isolate Streptococcus E-24 from the oropharynx of healthy children and explore its antibacteri-al effect on Pseudomonas aeruginosa as well as the molecular mechanism of anti-inflammatory injury.Methods Paper dispersion method was employed to observe the effective components of Streptococcus E-24 in inhibiting the growth of Pseudomonas aeruginosa.Subsequently,crystal violet staining and plate counting were utilized to assess the biofilm form-ation and adhesion ability of Pseudomonas aeruginosa.Finally,transmission electron microscopy,Western Blot and ELISA were employed to elucidate the molecular mechanism by which Streptococcus E-24 reverses Pseudomonas aeru-ginosa-induced pneumonia.Results After the cultivation of Streptococcus E-24,the fermented supernatant was found to contain an active ingredient inhibiting Pseudomonas aeruginosa,while the bacterial cells had no bacteriostatic activity.The supernatant from Streptococcus E-24 inhibited biofilm formation and adherence of Pseudomonas aeruginosa.Furthermore,it also suppressed the expression of ferroptosis-related proteins GPX4 and SLC7A11 in bronchial epithelial cells BEAS-2B and 16HBE induced by Pseudomonas aeruginosa.Additionally,the supernatant from Streptococcus E-24 inhibited the in-duction of expressions of inflammatory factors TNF-α,IL-6 and IL-8 in BEAS-2B and 16HBE cells by Pseudomonas aeru-ginosa.Conclusion As a potential microecological agent,Streptococcus E-24 isolated from oropharynx can inhibit the growth of Pseudomonas aeruginosa and inflammatory damage of respiratory cells,and play a protective role in human res-piratory health.
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