Association between miR-155 expression and Th17/Treg balance in URPL patients: a single-centre retrospective study

Unexplained recurrent pregnancy loss (URPL) is frequently associated with T helper 17 cells/regulatory T cells (Th17/Treg) imbalance, but the association between microRNA (miR)-155 and Th17/Treg imbalance remains unclear. Therefore, this study preliminarily analysed this association in URPL patients.

This retrospective study analysed 189 URPL patients (the live birth group: n = 112; the non-live birth group: n = 77) and 91 healthy pregnant women. miR-155, Th17 cells, Treg cells, and Th17/Treg-related cytokines were measured, and the association between miR-155 and Th17/Treg balance was evaluated. The discriminatory performance of miR-155 for adverse pregnancy outcomes (APOs) in URPL was explored with receiver operating characteristic (ROC) curves, and APOs-associated factors were analysed with logistic regression.

Serum miR-155 expression showed a graded decline: control group > live birth group > non-live birth group (all P < 0.001). The non-live birth group presented elevated Th17 cells, interleukin (IL)-17, IL-6, and Th17/Treg ratios but reduced Treg cells, IL-10, and transforming growth factor-beta 1 (TGF-β1) compared to other groups (all P < 0.001). miR-155 expression was correlated negatively with Th17 cells, Th17/Treg ratios, IL-17, and IL-6 and positively with Treg cells, IL-10, and TGF-β1 (all P < 0.001). For APOs in URPL patients, miR-155 expression had a strong discriminatory performance (area-under-the-curve = 0.801). Th17/Treg (OR = 1.048) and miR-155 (OR = 0.048) were independently associated with APOs in URPL (both P < 0.05).

Serum miR-155 is reduced in URPL patients and is associated with Th17/Treg imbalance. miR-155 may serve as an exploratory marker to aid in distinguishing APOs in URPL patients, however, its value requires external validation through prospective, multicentre studies.