Objective: The pathophysiology of the lung fibrotic process in systemic sclerosis (SSc) is not fully elucidated. Since this pattern represents the leading cause of death in SSc, the knowledge of its actual pathophysiology is basic to prevent and stage pulmonary damage. In this study, we aimed to further investigate the relationship between the functional profiles of bronchoalveolar lavage (BAL) T cells and the pulmonary manifestation of the disease.
Methods: With this aim, we assessed the frequency of Th1, Th2 and Th17 producing T-lymphocytes and their effector cytokines in BAL of SSc patients without signs or symptoms of lung interstitial involvement (SScFib-) and with interstitial lung fibrosis (SScFib+). We also study as control groups: patients with usual interstitial pneumonia (UIP), patients with sarcoidosis and 9 healthy controls (NHCs).
Results: SScFib- showed an increase in BAL Th1/Th2 balance compared to NHCs, which was even higher than that observed in sarcoidosis. SScFib+ showed a shift towards a lower Th1/Th2 ratio as compared to SScFib-. The frequency of Th17 BAL T cells did not change among study groups.
Conclusion: Our data confirm the Th1/Th2 imbalance hypothesis on the pathogenesis of interstitial fibrosis in SSc patients, and suggest a possible utility in the assessment of BAL Th1/Th2 ratio.