Background Although telomere erosion, a marker of immunosenescence, has been well established in rheumatoid arthritis and systemic lupus erythematosus, its impacts on systemic sclerosis (SSc) are still controversial.
Objectives To investigate immunosenescence status of SSc by measuring telomere lengths among different subsets of T cells, B cells and neutrophils.
Methods We enrolled 88 Korean patients with SSc (48.4±14.6 years) and 88 age- and sex- matched healthy controls (48.4±14.5 years). DNA of peripheral blood leukocytes (PBL) was extracted from whole blood of patients and controls. For subpopulation analysis, peripheral blood mononuclear cells (PBMC) were isolated from 20 patients and 20 controls. After isolating total CD4+, CD8+ T and B cells, subsets of T cells (naïve, CCR7+CD45RA+); central memory (CM, CCR7+CD45RA-); effector memory (EM, CCR7-CD45RA-) and terminal effector memory (TEM, CCR7-CD45RA+) and B cells (naïve, CD19+CD27-; memory, CD19+CD27+) were further isolated using FACSAria. Neutrophils were isolated using RBC lysis buffer from whole blood. Telomere length was measured in PBL, different subsets of T and B cells and neutrophils by monochrome multiplex quantitative PCR (MMQPCR) method . For each sample, the relative telomere to single copy gene (T/S) ratio (2-Δ Ct = [2Ct(telomere)/2Ct(albumin)]-1) was calculated to represent telomere length.
Results Telomere length was progressively shortened with aging in PBL from both SSc patients (r = -0.24, p=0.03) and controls (r= -0.24; p=0.02). For PBL, no significant difference of telomere length was found between SSc and controls (15.71±2.85 vs 16.08±2.77, p=0.38 by ANCOVA). However, telomere lengths were significantly shortened in either CD4+ or CD8+ T cells of SSc patients compared to those of controls (14.00±3.60 vs 18.21±7.45, p=0.024; 11.97±2.23 vs 14.53±4.18, p=0.013, respectively). When subpopulations of T cells were analysed, telomere lengths were shortened in naïve (15.34±4.27 vs 20.58±6.69, p=0.001), CM (12.55±2.40 vs 16.46±5.73,p=0.007) CD4+ T cells and EM CD8+ (10.66±2.22 vs 12.87±3.47,p=0.03) T cells of SSc patients compared with those of controls. In B cells, both naïve and memory B cells of SSc patients had shorter telomere than those of controls (13.89±3.68 vs 20.93±7.48,p=0.001; 15.47±7.14 vs 27.15±15.15,p=0.005, respectively). There was no difference of telomere erosions between SSc patients and controls in neutrophils. On the effect of clinical manifestations on telomere length, we found no significant difference of telomere lengths according to cutaneous subsets, anti-centromere antibody, anti-Scl70 antibody or internal organ involvement except lower telomere length of EM CD8+ T cells in patients with anti-Scl70 antibody (p=0.037).
Conclusions In SSc patients, telomere length is significantly shortened in CD4+, CD8+ T and B cells. Our findings suggest that immunosenescence of cells may contribute to the pathogenesis of SSc.
Cawthon, R. (2009). Nucleic Acids Research 37(3): e21
Disclosure of Interest None Declared