Study describes molecular mechanisms for postpartum RA reactivation

Innate immune functions play an important role in postpartum reactivation of rheumatoid arthritis (RA), according to the authors of a recent study. The investigators note that pregnancy is associated with reduced RA disease activity and frequently with disease exacerbation after delivery. To explore the molecular mechanisms of disease remission and postpartum reactivation, gene transcription profiles from peripheral blood mononuclear cells (PBMCs) were generated from six RA patients and eight healthy women during the third trimester and 24 weeks after delivery. During pregnancy only minor differences in gene expression and reduced lymphocyte and elevated monocyte gene activity in both groups; however, after delivery monocyte activity decreased in controls but persisted in RA patients, the authors reported. Furthermore, analysis of 32 immunologically relevant cellular pathways in the postpartum RA patients showed significant activation of genes related to adhesion, migration, defence of pathogens, and cell activation. The authors comment that their findings "support the hypotheses that molecular processes of inflammation in RA are suppressed during pregnancy but become activated postpartum." These observations, they add, "may be exploited therapeutically for induction of remission and prevention of relapse." The group concludes, "innate immune functions play an important role in postpartum reactivation of arthritis. However, this may depend not only on the monocyte itself, but also on the recurrence of lymphocyte functions postpartum and thus on a critical interaction between both arms of the immune system."...