The role of CECR1 in the immune-modulatory effects of butyrate and correlation between ADA2 and M1/M2 chemokines in tuberculous pleural effusion

Objectives: The Cat Eye Syndrome Critical Region, Candidate 1 (CECR1) gene encoding adenosine deaminase 2 (ADA2) is mainly expressed by macrophages. Given the immunomodulatory functions of butyrate, we examined the effect of butyrate on CECR1 expression of macrophages and the relationship between ADA2 and M1/M2 macrophages-associated chemokines in pleural fluid of patients with tuberculous pleural effusion (TPE). Methods: Expression of CECR1 was evaluated in lipopolysaccharide (LPS)-stimulated and/or butyrate treated THP-1 cells. The role of CECR1 on butyrate-induced immune response was evaluated using siRNA transfected THP-1 cells. M1/M2 chemokines and ADA2 were measured in pleural fluid of patients with TPE. Results: Butyrate promoted the expression of CECR1 and M2-macrophage markers in THP-1 cells. CECR1 was found to be involved in regulating M2 polarization in THP-1 cells treated with LPS and butyrate. Among chemokines measured in pleural fluid of patients with TPE, there was a significant negative correlation between CCL21 and ADA2 levels and between CCL25 and ADA2 levels, and a significant positive correlation between TGF-β and ADA2 levels and between IL-22 and ADA2 levels. Conclusions: CECR1 played an important role in the butyrate-modulated inflammatory responses in LPS-stimulated THP-1 cells. ADA2 may exert anti-inflammatory effects during the process of pleural inflammation in patients with TPE.