Background Transglutaminase 2 (TG 2) is a crosslinking enzyme that is known for tissue stabilization and immediate defense against injury or infection in many biological systems. Abnormal TG 2 activity in tissues contributes to a variety of diseases including autoimmune diseases.
Objectives The aim of this study was to investigate the mRNA expression of TG 2 on peripheral blood mononuclear cells (PBMCs) in patients with systemic lupus erythematosus (SLE) and in patients with rheumatoid arthritis (RA) and further to determine its association with clinical features.
Methods Forty patients with SLE (3 males, 37 females) and thirty two patients with RA (8 males, 24 females) attending outpatient clinics at Taichung Veterans General Hospital were enrolled in this study. Thirty three age-matched healthy subjects from the local community served as controls. About 30 mL blood was collected into sterile tubes containing EDTA. PBMCs were isolated with lymphocyte-separation medium by the density gradient separation. Total RNA was isolated from PBMCs of patients with SLE, patients with RA, and healthy subjects. RNA was extracted by using Trizol reagent and RNA samples were resuspended in diethyl pyrocarbonate-treated water followed by quantification of RNA concentration and purity by a spectrophotometer with calculating the ration of optical density at wavelengths of 260 and 280 nm. The first-strand cDNA for RT-PCR was synthesized from total RNA using the RT-PCR system. The cDNAs encoding human TG 2 and GAPDH were amplified by RT-PCR using the appropriate primer pairs, respectively.
Results The mRNA expression of TG 2 in SLE patients was significantly higher than that in RA patients and healthy controls. However, there was no significant difference for mRNA expression of TG 2 between RA patients and healthy controls. In SLE patients with aged 20-50 years, the mRNA expression of TG 2 tended to increase with age but was decreased in elderly SLE patients. In contrast, the mRNA expression of TG 2 tended to decrease with age in RA patients and elderly RA patients had lower mRNA expression of TG 2. In addition, there were correlations of TG 2 mRNA expression with clinical features in both SLE and RA patients.
Conclusions The mRNA expression of TG 2 was increased in patients with SLE. Age-related change in mRNA expression of TG 2 was observed in both SLE patients and RA patients. However, the differential mechanism for TG 2 involvement in the pathogeneses of autoimmune diseases including SLE and RA needs further investigation.
Disclosure of Interest None Declared