Novel synergistic therapeutic approach in idiopathic pulmonary fibrosis: Combining the antifibrotic nintedanib with the anti-inflammatory baricitinib.

BACKGROUND: Baricitinib and nintedanib can target inflammation and fibrosis respectively, which are the two most important processes in idiopathic pulmonary fibrosis (IPF). However, it is still unknown whether targeting these two processes simultaneously can synergistically improve the therapeutic effect of IPF. Therefore, it is necessary to predict the possible translational potential through preclinical studies.

METHODS: We evaluated both the in vitro and in vivo efficacy of a drug combination, nintedanib with baricitinb, a JAK1/JAK2 inhibitor. We first examined the fibroblast proliferation and myofibroblast differentiation of single agents or combinations by the MTT assay. Then we determined the migration of the fibroblasts by a wound healing assay. Meanwhile, we quantified the protein level of related growth factor or cytokines in the cell supernatant by ELISA. Finally, we investigated the therapeutic potential and mechanism in a bleomycin-induced mouse model.

RESULTS: Our results showed that the combination of nintedanib and baricitinib was more effective in suppressing fibroblast proliferation, myofibroblast transformation and fibroblast migration compared to either agent alone. In a bleomycin-induced IPF mouse model, the combination therapy resulted in a higher survival rate, increased body weight, and a lower lung/body weight ratio compared to the individual drugs. Moreover, both drugs improved lung functions in mice, but their combined administration led to superior outcomes. Histopathological analysis also revealed that the combination therapy mitigated pulmonary inflammation and fibrosis to a greater extent than the individual compounds. Mechanistically, baricitinib appears to orchestrate the effects of nintedanib in IPF by modulating the expression of genes such as il-6, tgf-β, col1α1 and fibronectin.

CONCLUSION: The synergistic targeting of inflammation by baricitinib and fibrosis by nintedanib preclinically improves IPF outcomes, thus suggesting their potential as a novel combination therapy for this condition.