The evaluation of the effect of triiodothyronine treatment on mice microbiome with pulmonary fibrosis

<strong>Abstract:</strong> <strong>Background:</strong> An interstitial lung disease without a known cause, idiopathic pulmonary fibrosis (IPF) has an unknown cause, high mortality, and frequent occurrence in the elderly, characterized by a progressive exacerbation of pulmonary fibrosis (PF) and eventually respiratory failure. An evaluation of the microbiota effects of triiodothyronine (T₃) treating bleomycin (BLM) mouse model is presented in this study. <strong>Methods:</strong> In a randomized design, 40 female SPF C57BL6/N mice, aged 8-12 weeks, weighed 18-25 g and assigned to 4 groups: Saline group, Saline + T₃ group, BLM group, and BLM + T₃ group, lung perfusion was performed with 1.5 U/kg BLM or equal volume (50 μl) 0.9% saline as control. On the days of 10th-20th, atomized T₃. In this study, 16S rRNA genes were sequenced in high-throughput to identify lung bacteria, and pathological lung changes were evaluated using HE staining and ELISA for TT₃, FT₃, and rT₃ levels in peripheral serum. <strong>Results: </strong>The microbiome decreased when induced with PF, but T₃ treatment can increase the amount, the abundance of Firmicutes increased, but the abundances of Proteobacteria, Bacteroides, and Actinomycetes decreased when induced with PF. Although T₃ treatment reverses the abundances of Firmicutes, Proteobacteria， and others, the damage caused by BLM and T₃ treatment did not cause significant differentiation to alpha and beta microbiome diversity. The microbiome abundance is inextricably linked to the concertation of total T₃and free T₃ in the serum. Furthermore, there was no significant impact on the function of the microbial community with the damage caused by BLM and the T₃ treatment. <strong>Conclusions:</strong> T₃ can improve the microbiota in PF but does not affect the diversity and biological functions of the microbiome, and it also indicates that T₃can become a new IPF treatment drug.