mRNA Quantification of T-bet, GATA-3, IFN-γ, and IL-4 Shows a Defective Th1 Immune Response in the Peripheral Blood from Rheumatoid Arthritis Patients: Link with Disease Activity

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Abstract
A T helper (Th)1 cytokine profile is predominant in the inflamed synovium of rheumatoid arthritis (RA). Since the situation in the blood is more controversial, we studied the Th1/Th2 balance in the peripheral blood of RA patients using mRNA markers. Total RNA was isolated directly from whole blood from 20 RA patients and 14 healthy controls. T-bet and GATA-3 transcription factors associated with Th1 and Th2 responses respectively, and IFNγ and IL-4 mRNA levels were measured by real-time PCR. In RA but not in control samples, T-bet mRNA levels correlated positively with IFNγ mRNA levels, and negatively with CRP levels. Accordingly, RA patients were divided into two groups according to CRP levels. In comparison to RA patients with a low CRP (CRP < 40 mg/l), patients with a high CRP (CRP≥40 mg/l) had lower IFNγ/β-actin, T-bet/β-actin mRNA levels and T-bet/GATA-3 expression ratios. In conclusion, RA blood cells showed a decreased Th1 situation as indicated by low IFNγ and T-bet mRNA expression. This pattern was found only in patients with the most active disease.