Simultaneous analysis of T cell clonality and cytokine production in rheumatoid arthritis using three-colour flow cytometry

BCR CDR3 length distributions differ between blood and spleen and between old and young patients, and TCR distributions can be used to detect myelodysplastic syndrome

Complementarity-determining region 3 (CDR3) is the most hyper-variable region in B cell receptor (BCR) and T cell receptor (TCR) genes, and the most critical structure in antigen recognition and thereby in determining the fates of developing and responding lymphocytes. There are millions of different TCR Vβ chain or BCR heavy chain CDR3 sequences in human blood. Even now, when high-throughput sequencing becomes widely used, CDR3 length distributions (also called spectratypes) are still a much quicker and cheaper method of assessing repertoire diversity. However, distribution complexity and the large amount of information per sample (e.g. 32 distributions of the TCRα chain, and 24 of TCRβ) calls for the use of machine learning tools for full exploration. We have examined the ability of supervised machine learning, which uses computational models to find hidden patterns in predefined biological groups, to analyze CDR3 length distributions from various sources, and distinguish between experimental groups. We found that (a) splenic BCR CDR3 length distributions are characterized by low standard deviations and few local maxima, compared to peripheral blood distributions; (b) healthy elderly people's BCR CDR3 length distributions can be distinguished from those of the young; and (c) a machine learning model based on TCR CDR3 distribution features can detect myelodysplastic syndrome with approximately 93% accuracy. Overall, we demonstrate that using supervised machine learning methods can contribute to our understanding of lymphocyte repertoire diversity.

The turnover of synovial T cells is higher than in T cells in the peripheral blood in persistent oligoarticular juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) summarizes a group of inflammatory diseases of childhood. The etiology remains still unclear. In JIA, T cells have been demonstrated to play key roles in the pathogenesis. T-cell proliferation in JIA may be different in the peripheral blood (PB) and the synovial fluid (SF). The aim of this study is to demonstrate the turnover of T cells in the PB and SF of patients with persistent oligoarticular JIA (oJIA) compared to controls. Matched pairs of samples were investigated derived from PB and SF of nine patients with persistent oJIA. The cells from PB and SF were determined by flow cytometry. The majority of the PBMC and IAMC were in phase G0/G1, with fewer than 1% in S phase. In the SF, the percentage of cells in the S phase are higher than in the PB. The percentage of cells in the S phase in SF are equal to the result in the control group. In conclusion, the turnover of synovial T cells in persistent oJIA is higher than in the PB.

Premature aging of the immune system in children with juvenile idiopathic arthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is an autoimmune disease of the young. The pathogenesis is not completely understood. Premature aging, associated thymic involution, and compensatory autoproliferation could play important roles in the pathogenesis of autoimmunity. We undertook this study to determine whether patients with JIA demonstrate premature immunosenescence.

METHODS

To test this hypothesis, we measured 3 indicators of aging: the percentages and total counts of peripheral blood naive T cells, the frequency of T cell receptor excision circles (TRECs) in naive T cells, and telomeric erosion and Ki-67 expression as estimates of the replicative history of homeostatic proliferation.

RESULTS

JIA patients showed an accelerated loss of CD4+,CD45RA+,CD62L+ naive T cells with advancing age and a compensatory increase in the number of CD4+,CD45RO+ memory T cells. JIA patients demonstrated a significantly decreased frequency of TRECs in CD4+,CD45RA+ naive T cells compared with age-matched healthy donors (P = 0.002). TREC numbers correlated with age only in healthy donors (P = 0.0001). Telomeric erosion in CD4+,CD45RA+ naive T cells was increased in JIA patients (P = 0.01). The percentages of Ki-67-positive CD4+,CD45RA+ naive T cells were increased in JIA patients (P = 0.001) and correlated with disease duration (P = 0.003), which was also an independent factor contributing to telomeric erosion (P = 0.04).

CONCLUSION

Our findings suggest that age-inappropriate T cell senescence and disturbed T cell homeostasis may contribute to the development of JIA. In patients with JIA, dysfunction in the ability to reconstitute the T cell compartment should be considered when exploring new therapeutic strategies.

Premature immunosenescence in rheumatoid arthritis and multiple sclerosis patients

Patients with T-cell-mediated autoimmune diseases show immune system abnormalities that resemble the typical characteristics of autoimmune dysfunction described in the elderly. In addition, the incidence of autoimmune disease increases with advancing age. To evaluate whether patients with rheumatoid arthritis (RA) and multiple sclerosis (MS) have premature immuno-senescence, we measured two indicators of aging: the number of T-cell-receptor excision circles (TRECs) and the percentage of CD4+CD28(null) T cells. We studied them in the peripheral blood mononuclear cells (PBMCs) of 60 RA patients, 32 MS patients, and 40 healthy controls (HCs). We found that TREC numbers were lower in RA and MS patients than in age-matched HCs, indicating premature thymic involution. Moreover, a subset of these patients contained age-inappropriate high frequencies of CD4+CD28(null) T cells. This study provides evidence of premature immune system senescence in both RA and MS patients. Premature aging could be a risk factor for developing autoimmune disorders in genetically predisposed individuals in a susceptible environment.

Impaired activation-induced telomerase activity in PBMC of early but not chronic rheumatoid arthritis patients

Although telomerase activity is important in normal immune function, it is unclear whether telomerase or telomerase (dys)regulation plays a role in the pathogenic immune response in autoimmune diseases like rheumatoid arthritis (RA). In this study, we evaluated the dynamics of the activation-induced human telomerase reverse transcriptase (hTERT) response in RA patients and non-RA controls. The expression of the catalytic subunit of telomerase, hTERT, was measured in peripheral blood mononuclear cells (PBMC) of RA patients and controls after in vitro stimulation with anti-CD3 monoclonal antibody (mAb) using real-time PCR. Anti-CD3 mAb stimulation induced activation and proliferation of the T cells in all populations studied. In early RA patients with a disease duration of less than 1 year, the activation-induced hTERT mRNA levels were found to be reduced as compared to healthy controls (HC). Chronic RA patients, with a disease duration of more than 1 year, did not show these impaired hTERT mRNA levels after stimulation with anti-CD3 mAb. Decreased hTERT mRNA levels were also found in multiple sclerosis patients and patients suffering from flu-like symptoms, indicating that these deviations are not disease-specific. The impaired activation-induced hTERT response in PBMC may be a general response of the immune cells in cases of acute or chronic immune activation, presumably to control unwanted clonal expansions and to maintain the diversity of the TCR repertoire. Our results also indicate that clonal T cell expansions, described in RA, are probably not mediated by an elevated potency to express hTERT.

Single-nucleotide polymorphisms of the interleukin-18 gene promoter region in rheumatoid arthritis patients: protective effect of AA genotype

Rheumatoid arthritis (RA) is a chronic arthritic condition that can lead to deformities and disabilities. Although numerous studies reported the association of human leukocyte antigen (HLA)-DRB1*04 and RA, other genes, e.g. cytokines genes, may contribute towards disease susceptibility. Interleukin-18 (IL-18) is a proinflammatory cytokine postulated to play a role in the acute and chronic inflammatory phases of RA. The IL-18 protein expression seems to be regulated by two single-nucleotide polymorphisms (SNPs) located at positions -607 and -137 in the promoter region of the gene. It is postulated that specific alleles may be associated with susceptibility to the development of RA. In the present study, we described the IL-18 gene promoter region genotypes and combined genotypes (-607/-137) in 106 RA patients and 273 unrelated healthy controls to evaluate the contributions of these alleles to RA predisposition in Chinese, Malays, and Indians. The genotyping were performed using sequence-specific polymerase chain reactions. Rheumatoid factors were assayed by enzyme-linked immunosorbent assay. Biodata were obtained through chart review. The controls had significantly higher frequency of AA genotype at position -607 when compared to RA patients. No significant differences were observed in the distribution of either allelic or genotypic frequencies at position -137. There was no association between the genotypes and the presence of rheumatoid factors. This study did not find evidence of a genetic susceptibility factor but demonstrated the novel finding that the AA genotype at position -607 is associated with a protective effect against development of RA in Chinese individuals. This protection may be mediated through inhibition of cyclic (Adenosine 3', 5'-cyclic monophosphate) AMP-responsive element (CRE)-binding protein by the disruption of the CRE consensus sequence.