IL1B and pulmonary arterial hypertension: In contrast to our results in LoS cohort, serum IL-1β, but not IL-1α, was positively correlated with the severity of skin involvement in SSc measured by modified Rodnan skin score (mRSS), suggesting a potential role of this cytokine in SSc fibrotic complications, but serum levels of both IL-1α and IL-1β positively correlated with carbon monoxide transfer coefficient and patients with high serum IL-1β had higher DLCO, suggesting a reduced risk of lung fibrosis and PAH [54].