Sarcoidosis is a systemic granulomatous disease, which is thought to result from an aberrant immune response. CD4⁺ T lymphocytes play an important role in the development of granulomas. Previously, the immunopathogenesis of sarcoidosis was focused on Th1/Th2 disturbances. The aim of this study was to evaluate the balance between newer CD4⁺ T lymphocytes, i.e., Treg and Th17 cells. In our studies, a decrease in Treg cells and an increase in Th17 cells were observed in the peripheral blood and BALF of sarcoidosis patients. A significant increase in the Th17/Treg cell ratio was observed in sarcoidosis patients. After treatment with prednisone, the expression of Foxp3 mRNA was elevated in the peripheral blood, and expression of (ROR)γt mRNA showed a downward trend. These findings suggest that sarcoidosis is associated with an imbalance between Th17 and Treg cells in peripheral blood and BALF. Therefore, targeting the cytokines that affect the Th17/Treg ratio could provide a new promising therapy for pulmonary sarcoidosis.

The mechanisms underlying the pathogenesis of idiopathic pulmonary fibrosis (IPF) involve multiple pathways, such as inflammation, epithelial mesenchymal transition, coagulation, oxidative stress, and developmental processes. The small GTPase, RhoA, and its target protein, Rho-kinase (ROCK), may interact with other signaling pathways known to contribute to pulmonary fibrosis. This study aimed to determine the beneficial effects and mechanisms of fasudil, a selective ROCK inhibitor, on bleomycin-induced pulmonary fibrosis in mice. Our results showed that the Aschcroft score and hydroxyproline content of the bleomycin-treated mouse lung decreased in response to fasudil treatment. The number of infiltrated inflammatory cells in the bronchoalveolar lavage fluid (BALF) was attenuated by fasudil. In addition, fasudil reduced the production of transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), alpha-smooth muscle actin (α-SMA), and plasminogen activator inhibitor-1 (PAI-1) mRNA and protein expression in bleomycin-induced pulmonary fibrosis. These findings suggest that fasudil may be a potential therapeutic candidate for the treatment of pulmonary fibrosis.

Pulmonary involvement is a common feature of MPA. Although alveolar hemorrhage is the most common pulmonary manifestation of MPA, a few recent studies have described instances of MPA patients with pulmonary fibrosis. Pulmonary fibrosis was seen to predate, be concomitant with, or occur after the diagnosis of MPA. The goal of this study was to describe the clinical features and prognosis of microscopic polyangiitis (MPA) patients whose initial respiratory presentation was pulmonary fibrosis.