Efficacy of baricitinib in treating rheumatoid arthritis: Modulatory effects on fibrotic and inflammatory biomarkers in a real-life setting

Background: Baricitinib is a JAK inhibitor that blocks intracellular signalling pathways of inflammatory cytokines recommended for Rheumatoid arthritis (RA) patients not responding to initial treatment. Among RA extrareticular features, interstitial lung involvement is primarly characterized by fibrotic evolution. The aim of the present study was to analyse the effects of baricitinib in a population of RA and RA-ILD patients in a real-life setting, describing any changes in lung function parameters, serum inflammatory biomarkers and fibrotic biomarkers after 6 months of treatment. Materials and methods: 15 patients (median (IQR) 65 (55–66); 13% males and 74% smokers) treated with baricitinib were enrolled. 4 patients (27%) were classified as RA-ILD before baricitinib therapy. Our study is the first to evaluate adipokine levels in RA patients (including a small population with RA-ILD) after six months of baricitinib treatment with a novel multiplex method. Results: The modulatory effects of baricitinib on lipid mediators were associated with clinical and functional improvement, demonstrated by the significant increase in DLco and KCO percentages after six months of treatment. Baricitinib decreased the systemic inflammation by lowering expression of IL-6 and CRP and reducing ESR and serum concentrations of adiponectin. A significant reduction of KL-6 levels in RA-ILD patients after six months of baricitinib therapy reflects the stability of interstitial lung involvement in these patients. Conclusion: Baricitinib was demonstrated to be a safe immune modulator that reduces the concentrations biomarkers of lung fibrosis and inflammation in RA patients, including a subgroup with interstitial lung involvement.