Serum Cytokine Profiles in Patients with Rheumatoid Arthritis Before and After Treatment with Methotrexate

Abstract

Rheumatoid arthritis (RA) is an inflammatory autoimmune illness affecting around 1% of the population globally. Cytokines have a crucial role in the pathogenesis of RA. The objectives of the present study were to compare the serum cytokine profiles between methotrexate (MTX)-treated and MTX-naive RA patient groups, MTX-treated RA patient group and healthy controls, and MTX-naive RA patient group and healthy controls. Enzyme linked immunosorbent assay (ELISA) kits were used to quantify the serum concentrations of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-17, IL-6, interferon-gamma (IFN-γ), and IL-10 in 80 RA patients (48 MTX treated and 32 MTX naive) and 80 healthy controls. For all cytokine assays, absorbance was measured at 450 nm using a microplate reader (Bio-Rad). Independent sample t-test was used to compare the serum cytokine concentrations between the study groups using SPSS version 25. MTX-treated RA patient group had significantly reduced serum levels of TNF-α (36.13 ± 17.64 versus 45.82 ± 23.07, *P = 0.037), IL-17 (307.85 ± 151.74 versus 435.42 ± 241.19, **P = 0.006), and IFN-γ (414.93 ± 212.13 versus 527.15 ± 269.61, *P = 0.041) compared to MTX-naive RA patients. Both MTX-treated and MTX-naive RA patient groups had significantly high serum levels of TNF-α, IL-1β, IL-17, IL-6, IFN-γ, and IL-10 when compared to healthy controls (***P < 0.001). Downregulation of the serum concentrations of certain key cytokines, viz. TNF-α, IL-17, and IFN-γ, demonstrates the anti-inflammatory effect of MTX in RA patients.

Keywords: IFN-γ; IL-17; IL-1β; TNF-α; methotrexate; rheumatoid arthritis.