miR-155-5p/FOXO3a promotes pulmonary fibrosis in rats by mediating NLRP3 inflammasome activation

Abstract

Objective

Pulmonary fibrosis (PF) is regarded as progressive lung disease. miR-155-5p depletion exerts anti-fibrotic effects in silicotic mice. This study explored the effect and possible mechanism of miR-155-5p in PF rats, hoping to find a new target for PF management.

Methods

Bleomycin-induced PF rat model was established. Alveolar structure and collagen fiber deposition were observed by HE and Elastica-Masson staining. Alveolitis and PF scores were evaluated using the method of Szapiel. Total collagen content was detected using the Sircol method. PF rats were intraperitoneally injected with NLRP3 inhibitor MCC950 or intravenously injected with miR-155-5p antagomir and si-FOXO3a lentivirus plasmids. Binding sites of miR-155-5p and FOXO3a were predicted using bioinformatics analysis and dual-luciferase reporter assay. The expressions of miR-155-5p, NLRP3, ASC, caspase-1, IL-1β, IL-18, and FOXO3a were detected by RT-qPCR, Western blot, and ELISA.

Results

MCC950 treatment inhibited NLRP3 inflammasome, alleviated alveolar hemorrhage and alveolitis, and reduced blue collagen fiber deposition, scores of alveolitis and PF, and levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in PF rats. miR-155-5p was elevated in lung tissues of PF rats. Inhibition of miR-155-5p downregulated levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in lung tissues of PF rats. miR-155-5p targeted FOXO3a. miR-155-5p inhibition and silencing FOXO3a exacerbated alveolitis and PF in rats and increased levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18.

Conclusions

miR-155-5p aggravated alveolitis and promoted PF by targeting FOXO3a and prompting the activation of NLRP3 inflammasome and then inducing IL-1β and IL-18 release.

Keywords:

• Pulmonary fibrosis
• NLRP3 inflammasome
• Collagen fiber
• miR-155-5p
• FOXO3a
• Caspase-1
• IL-1β
• IL-18

Ethics approval

All animal experiments were reviewed and approved by the Ethics Committee of Wujin Hospital Affiliated with Jiangsu University (Approval number 20200304b416 [19], Approval date 2021.3.25). Significant efforts were made to minimize animal number and suffering. All animal experiments comply with the ARRIVE guidelines.

Author contributions

LW contributed to the study concepts and study design, LP contributed to the guarantor of integrity of the entire study; LP contributed to the literature research; LW contributed to the experimental studies and data acquisition; LW, LP contributed to the manuscript preparation and ZZ contributed to the manuscript editing and review. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All the data generated or analyzed during this study are included in this published article.