Smoking promotes exacerbated inflammatory features in dendritic cells of Chilean rheumatoid arthritis patients

The dual potential to promote tolerance or inflammation when facing self-antigens makes dendritic cells (DCs) fundamental players in autoimmunity. There is an association between smoking and DCs maturation in patients with rheumatoid arthritis (RA). However, ethnicity is a key factor in autoimmune disorders.

To evaluate phenotypic and functional alterations of DCs obtained from Chilean patients with RA as compared to healthy controls (HC). In second term, to compare the inflammatory behaviour of DCs between smoker and non-smoker patients.

Monocyte-derived DCs and T-cells were obtained from blood samples isolated from 30 HC and 32 RA-patients, 14 of which were currently smokers and 18 non-smokers. Several maturation surface markers were evaluated in DCs, including HLA-DR, CD40, CD80, CD83 and CD86. Furthermore, autologous co-cultures of DCs and T-cells were carried out and then T-cell proliferation, and expansion of Th1, Th17 and Tregs were analysed.

Compared with HC, RA-patients displayed increased HLA-DR expression in DCs, which was manifested mainly in patients with moderate-to- high disease activity scores (DAS28). Furthermore, RA-patients presented a stronger Th17-expansion and a correlation between DAS28 and Th1-expansion. Both effects were mainly observed in patients in remission or with a low DAS28. Moreover, smoker RA-patients displayed enhanced HLA-DR and CD83 expression in DCs as well as an exacerbated Th17-expansion and a correlation between DAS28 and Th1-expansion.

These findings suggest that smoking enhances the inflammatory behaviour of DCs and the consequent Th1 and Th17-mediated response in patients with RA.