Circulating cytotoxic CD8(+) CD28(-) T cells in ankylosing spondylitis

Causal relationship between immune cells and the risk of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis: A Mendelian randomization study

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare inflammatory disease categorized as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. The majority of patients are ANCA-positive, predominantly against myeloperoxidase (MPO). Previous studies have predominantly concentrated on the association between EGPA and neutrophils, but recent research has emphasized the role of lymphocytes in the development of EGPA. The objective of our research was to examine the causal association between immune cells and MPO + ANCA EGPA. A two-sample bidirectional Mendelian randomization (MR) analysis was performed, which included 159 MPO + ANCA EGPA cases and 6688 controls and utilized Genome-Wind Associaton Studies (GWAS) summary statistics of immune traits from approximately 3757 individuals, encompassing around 22 million single nucleotide polymorphisms (SNPs). Our findings revealed that 23 immunophenotypes were associated with MPO + ANCA EGPA. Furthermore, the reverse MR analysis showed that MPO + ANCA EGPA had significant causal effects on three immunophenotypes within the Treg panel. By integrating existing research, our study unveiled the contributions of Tregs, B cells, and monocytes to the development of EGPA. Subgroup analysis specifically examined the roles of lymphocyte subtypes, cytokines, and their surface molecules in the pathogenic mechanisms of the disease. This comprehensive approach provides a novel perspective on the biological mechanisms and early intervention strategies for MPO + ANCA EGPA by focusing on immune cells.

Natural Killer Cells and Cytotoxic T Cells: Complementary Partners against Microorganisms and Cancer

Natural killer (NK) cells and cytotoxic T (CD8+) cells are two of the most important types of immune cells in our body, protecting it from deadly invaders. While the NK cell is part of the innate immune system, the CD8+ cell is one of the major components of adaptive immunity. Still, these two very different types of cells share the most important function of destroying pathogen-infected and tumorous cells by releasing cytotoxic granules that promote proteolytic cleavage of harmful cells, leading to apoptosis. In this review, we look not only at NK and CD8+ T cells but also pay particular attention to their different subpopulations, the immune defenders that include the CD56+CD16dim, CD56dimCD16+, CD57+, and CD57+CD16+ NK cells, the NKT, CD57+CD8+, and KIR+CD8+ T cells, and ILCs. We examine all these cells in relation to their role in the protection of the body against different microorganisms and cancer, with an emphasis on their mechanisms and their clinical importance. Overall, close collaboration between NK cells and CD8+ T cells may play an important role in immune function and disease pathogenesis. The knowledge of how these immune cells interact in defending the body against pathogens and cancers may help us find ways to optimize their defensive and healing capabilities with methods that can be clinically applied.

What do we know about co-stimulatory and co-inhibitory immune checkpoint signals in ankylosing spondylitis?

Ankylosing spondylitis is the main entity of a family of inflammatory diseases affecting many musculoskeletal (sacroiliac joints, spine, and peripheral joints) and extra-musculoskeletal sites, termed spondyloarthritis. While it is debated whether disease onset is primarily driven by autoimmune or autoinflammatory processes, what is certain is that both innate and adaptive immune responses orchestrate local and systemic inflammation, which leads to chronic pain and immobility. Immune checkpoint signals are one key player in keeping the immune system in check and in balance, but their role in disease pathogenesis is still rather elusive. Therefore, we ran a MEDLINE search utilizing the PubMed platform for a variety of immune checkpoint signals in regard to ankylosing spondylitis. In this review, we summarize the experimental and genetic data available and evaluate the relevance of immune checkpoint signalling in the pathogenesis of ankylosing spondylitis. Markers such as PD-1 and CTLA-4 have been extensively studied and facilitate the concept of an impaired negative immune regulation in ankylosing spondylitis. Other markers are either neglected completely or insufficiently examined, and the data is conflicting. Still, some of those markers remain interesting targets to decipher the pathogenesis of ankylosing spondylitis and to develop new treatment strategies.

Age-related mechanisms in the context of rheumatic disease

Ageing is characterized by a progressive loss of cellular function that leads to a decline in tissue homeostasis, increased vulnerability and adverse health outcomes. Important advances in ageing research have now identified a set of nine candidate hallmarks that are generally considered to contribute to the ageing process and that together determine the ageing phenotype, which is the clinical manifestation of age-related dysfunction in chronic diseases. Although most rheumatic diseases are not yet considered to be age related, available evidence increasingly emphasizes the prevalence of ageing hallmarks in these chronic diseases. On the basis of the current evidence relating to the molecular and cellular ageing pathways involved in rheumatic diseases, we propose that these diseases share a number of features that are observed in ageing, and that they can therefore be considered to be diseases of premature or accelerated ageing. Although more data are needed to clarify whether accelerated ageing drives the development of rheumatic diseases or whether it results from the chronic inflammatory environment, central components of age-related pathways are currently being targeted in clinical trials and may provide a new avenue of therapeutic intervention for patients with rheumatic diseases.

CD8+ T Cell Senescence: Lights and Shadows in Viral Infections, Autoimmune Disorders and Cancer

CD8⁺ T lymphocytes are a heterogeneous class of cells that play a crucial role in the adaptive immune response against pathogens and cancer. During their lifetime, they acquire cytotoxic functions to ensure the clearance of infected or transformed cells and, in addition, they turn into memory lymphocytes, thus providing a long-term protection. During ageing, the thymic involution causes a reduction of circulating T cells and an enrichment of memory cells, partially explaining the lowering of the response towards novel antigens with implications in vaccine efficacy. Moreover, the persistent stimulation by several antigens throughout life favors the switching of CD8⁺ T cells towards a senescent phenotype contributing to a low-grade inflammation that is a major component of several ageing-related diseases. In genetically predisposed young people, an immunological stress caused by viral infections (e.g., HIV, CMV, SARS-CoV-2), autoimmune disorders or tumor microenvironment (TME) could mimic the ageing status with the consequent acceleration of T cell senescence. This, in turn, exacerbates the inflamed conditions with dramatic effects on the clinical progression of the disease. A better characterization of the phenotype as well as the functions of senescent CD8⁺ T cells can be pivotal to prevent age-related diseases, to improve vaccine strategies and, possibly, immunotherapies in autoimmune diseases and cancer.

The Prevalence of Autoimmune Diseases in Patients with Primary Open-Angle Glaucoma Undergoing Ophthalmic Surgeries

PURPOSE

To assess the prevalence of autoimmune disease (AiD) in patients with primary open-angle glaucoma (POAG) undergoing ophthalmic surgery.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Patients with POAG undergoing any ophthalmic surgery and control subjects undergoing cataract surgery at the Massachusetts Eye and Ear from March 2019 to April 2020.

METHODS

All available medical records with patient demographics, ocular, and medical conditions were reviewed. Differences in AiD prevalence were assessed and adjusted for covariates using multiple logistic regression. Additionally, a subgroup analysis comparing the POAG patients with and without AiD was performed.

MAIN OUTCOME MEASURES

To assess the prevalence of AiD based on the American Autoimmune Related Diseases Association list.

RESULTS

A total of 172 patients with POAG and 179 controls were included. The overall prevalence of AiD was 17.4% in the POAG group and 10.1% in the controls (P = 0.044); 6.4% of POAG patients and 3.4% of controls had more than 1 AiD (P = 0.18). The most prevalent AiDs in POAG group were rheumatoid arthritis (4.6%) and psoriasis (4.1%), which were also the most common in controls (2.8% each). In a fully adjusted multiple logistic regression analysis accounting for steroid use, having an AiD was associated with 2.62-fold increased odds of POAG relative to controls (95% confidence interval, 1.27-5.36, P = 0.009); other risk factors for POAG derived from the analysis included age (odds ratio [OR], 1.04, P = 0.006), diabetes mellitus (OR, 2.31, P = 0.008), and non-White ethnicity (OR, 4.75, P < 0.001). In a case-only analysis involving the eye with worse glaucoma, there was no statistical difference in visual field mean deviation or retinal nerve fiber layer (RNFL) thickness in POAG patients with AiD (n = 30) and without AiD (n = 142, P > 0.13, for both).

CONCLUSIONS

A higher prevalence of AiD was found in POAG patients compared with control patients undergoing ophthalmic surgery. The presence of AiD was associated with increased risk for POAG after adjusting for covariates. Additional factors may have prevented a difference in RNFL thickness in POAG patients with and without AiD. Autoimmunity should be explored further in the pathogenesis of POAG.

Cellular and molecular diversity in spondyloarthritis

The spondyloarthritides are a cluster of inflammatory rheumatic diseases characterized by different diagnostic entities with heterogeneous phenotypes. The current classification system groups spondyloarthritis patients in two main categories, axial and peripheral spondyloarthritis, providing a framework wherein the clinical picture guides the treatment. However, the heterogeneity of the clinical manifestations of the pathologies, even when residing in the same group, highlights the importance of analyzing the smallest features of each entity to understand how different cellular subsets evolve, what the underlying mechanisms are and what biological markers can be identified and validated to evaluate the stage of disease and the corresponding efficacy of treatments. In this review, we will focus mostly on axial spondyloarthritis, report current knowledge concerning the cellular populations involved in its pathophysiology, and their molecular diversity. We will discuss the implications of such a diversity, and their meaning in terms of patients' stratification.

Association between senescence of T cells and disease activity in patients with systemic lupus erythematosus

Objectives

Systemic lupus erythematosus (SLE) patients are predisposed to chronic immune activation, leading to accelerated immunosenescence. The aging of the immune system causes the T cells to express several senescence markers such as CD57 and KLRG1, which produce pro-inflammatory cytokine interferon γ (IFN-γ). Immunosenescence was associated with high morbidity and mortality in other diseases. This research was conducted to prove the association between senescent T cells and SLE disease activity.

Material and methods

This research was an observational cross-sectional study on 53 women aged 16–45 years diagnosed with SLE based on SLICC 2012 criteria. All subjects were recorded for demographic and clinical data, and their SLE disease activity index (SLEDAI) score was measured to evaluate disease activity. Active disease was defined as SLEDAI score ≥ 3. The CD57 antigen and KLRG1 expression on CD4+ and CD8+ T cells were calculated from peripheral blood mononuclear cells (PBMC) by flow cytometry. Interferon γ was measured from serum using ELISA. The comparison was done using the Mann-Whitney U test, and correlation was tested using the Spearman test. Associations between variables were calculated using linear regression models.

Results

Systemic lupus erythematosus patients with active disease had markedly higher CD4+KLRG1+ (3.1 [1.3–5.5]% vs. 0.3 [0.1–0.5]%), CD8+CD57+ (11.6 ±7.1% vs. 2.4 ±2.0%, p = 0.000), and CD8+KLRG1+ T cell percentages (13.7 ±7.5% vs. 0.3 ±0.1%, p = 0.000), and IFN- γ levels (208.9 [148.3–233.8] vs. 146.7 [130.2–210.8] pg/ml, p = 0.048), compared to the inactive patients. Positive correlation and association was found between the CD8+CD57+ and CD8+KLRG1+ percentages with the SLEDAI score (p = 0.007 and p = 0.007, for the linear regression analysis, respectively).

Conclusions

Systemic lupus erythematosus patients showed significantly higher senescence T cell markers compared to controls, and the increase of T cell senescence, especially in the CD8 compartment, has some association with increased disease activity in patients with SLE.

Integrative Single-Cell RNA-Seq and ATAC-Seq Analysis of Peripheral Mononuclear Cells in Patients With Ankylosing Spondylitis

Objective

Genetic studies on ankylosing spondylitis (AS) have identified more than 100 pathogenic genes. Building a bridge between these genes and biologically targeted therapies is the current research hotspot.

Methods

We integrated single-cell assaying transposase-accessible chromatin sequencing (scATAC-seq) and single-cell RNA sequencing (scRNA-seq) to explore the key genes and related mechanisms associated with AS pathogenesis.

Results

We identified 18 cell types in peripheral mononuclear cells from patients with AS and normal controls and summarized the cell-type-specific abnormal genes by scRNA-seq. Interestingly, we found that the pathogenic gene NFKB involved in AS progression originated from CD8+ T cells. Moreover, we observed an abnormal tumor TNF pathway mediated by abnormal expression of TNF, NFKB, FOS, JUN, and JUNB, and scATAC-seq results confirmed the abnormal accessible binding sites of transcriptional factors FOS, JUN, and JUNB. The final magnetic bead sorting and quantitative real-time PCR(RT-qPCR) confirmed that NFKB, FOS, JUN, and JUNB in CD8+ T cells differed in the AS group.

Conclusions

Our results revealed a possible mechanism by which NFKB abnormally regulates FOS, JUN, and JUNB and drives AS progression, providing a novel perspective from a single cell point of view in AS.

Allotransplantation Is Associated With Exacerbation of CD8 T-Cell Senescence: The Particular Place of the Innate CD8 T-Cell Component

Immunosenescence is a physiological process that is associated with changes in the immune system, particularly among CD8 T-cells. Recent studies have hypothesized that senescent CD8 T-cells are produced with chronologic age by chronic stimulation, leading to the acquisition of hallmarks of innate-like T-cells. While conventional CD8 T-cells are quite well characterized, CD8 T-cells sharing features of NK cells and memory CD8 T-cells, are a newly described immune cell population. They can be distinguished from conventional CD8 T-cells by their combined expression of panKIR/NKG2A and Eomesodermin (E), a unique phenotype closely associated with IFN-γ production in response to innate stimulation. Here, we first provided new evidence in favor of the innate character of panKIR/NKG2A(+) E(+) CD8 T-cells in normal subjects, documenting their position at an intermediate level in the innateness gradient in terms of both innate IFN-γ production and diminished mitochondrial mass. We also revealed that CD8 E(+) panKIR/NKG2A(+) T-cells, hereafter referred to as Innate E(+) CD8 T-cells, exhibit increased senescent (CD27(-) CD28(-)) phenotype, compared to their conventional memory counterparts. Surprisingly, this phenomenon was not dependent on age. Given that inflammation related to chronic viral infection is known to induce NK-like marker expression and a senescence phenotype among CD8 T-cells, we hypothesized that innate E(+) CD8 T-cells will be preferentially associated with exacerbated cellular senescence in response to chronic alloantigen exposure or CMV infection. Accordingly, in a pilot cohort of stable kidney allotransplant recipients, we observed an increased frequency of the Innate E(+) CD8 T-cell subset, together with an exacerbated senescent phenotype. Importantly, this phenotype cannot be explained by age alone, in clear contrast to their conventional memory counterparts. The senescent phenotype in CD8 T-cells was further increased in cytomegalovirus (CMV) positive serology transplant recipients, suggesting that transplantation and CMV, rather than aging by itself, may promote an exacerbated senescent phenotype of innate CD8 T-cells. In conclusion, we proposed that kidney transplantation, via the setting of inflammatory stimuli of alloantigen exposure and CMV infection, may exogenously age the CD8 T-cell compartment, especially its innate component. The physiopathological consequences of this change in the immune system remain to be elucidated.

CD8+ Tregs revisited: A heterogeneous population with different phenotypes and properties

Regulatory T cells (Tregs) play a key role in the peripheral self-tolerance and preventing autoimmunity. While classical CD4⁺ Foxp3⁺ Tregs are well established, their CD8⁺ counterparts are still controversial in many aspects including their phenotypic identity and their mechanisms of suppression. Because of these controversies and because of only a limited number of studies documenting the immunoregulatory function of CD8⁺ Tregs in vivo, the concept of CD8⁺ Tregs is still not unanimously accepted. We propose that any T-cell subset considered as true regulatory must be distinguishable from other cell types and must suppress in vivo immune responses via a known mechanism. In this article, we revisit the concept of CD8⁺ Tregs by focusing on the characterization of individual CD8⁺ T-cell subsets with proposed regulatory capacity separately. Therefore, we review the phenotype and function of CD8⁺ FOXP3⁺ T cells, CD8⁺ CD122⁺ T cells, CD8⁺ CD28^low/- T cells, CD8⁺ CD45RC^low T cells, T cells expressing CD8αα homodimer and Qa-1-restricted CD8⁺ T cells to show whether there is sufficient evidence to establish these subsets as bona fide Tregs. Based on the intrinsic ability of CD8⁺ Treg subsets to promote immune tolerance in animal models, we elaborate on their potential use in clinics.

Osteoimmunological insights into the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS.

Inclusion body myositis: clinical features and pathogenesis

Inclusion body myositis (IBM) is often viewed as an enigmatic disease with uncertain pathogenic mechanisms and confusion around diagnosis, classification and prospects for treatment. Its clinical features (finger flexor and quadriceps weakness) and pathological features (invasion of myofibres by cytotoxic T cells) are unique among muscle diseases. Although IBM T cell autoimmunity has long been recognized, enormous attention has been focused for decades on several biomarkers of myofibre protein aggregates, which are present in <1% of myofibres in patients with IBM. This focus has given rise, together with the relative treatment refractoriness of IBM, to a competing view that IBM is not an autoimmune disease. Findings from the past decade that implicate autoimmunity in IBM include the identification of a circulating autoantibody (anti-cN1A); the absence of any statistically significant genetic risk factor other than the common autoimmune disease 8.1 MHC haplotype in whole-genome sequencing studies; the presence of a marked cytotoxic T cell signature in gene expression studies; and the identification in muscle and blood of large populations of clonal highly differentiated cytotoxic CD8⁺ T cells that are resistant to many immunotherapies. Mounting evidence that IBM is an autoimmune T cell-mediated disease provides hope that future therapies directed towards depleting these cells could be effective.

Altered Cytotoxicity Profile of CD8+ T Cells in Ankylosing Spondylitis

OBJECTIVE

Ankylosing spondylitis (AS) is an inflammatory arthritis in which men have a higher risk of developing progressive axial disease than women. Transcriptomic studies have shown reduced expression of cytotoxic cell genes in the blood of AS patients. HLA-B27 contributes the greatest risk for AS, suggesting a role for CD8+ T cells. This study was undertaken to profile AS patient cytotoxic cells with the hypothesis that an alteration in CD8+ T cells might explain the aberrant cytotoxic profile observed in patients.

METHODS

Whole blood was examined for GZM and PRF1 gene expression by quantitative polymerase chain reaction. Serum and synovial fluid (SF) were examined for granzyme and perforin 1 expression by bead array, and blood and SF mononuclear cells were examined for granzyme and perforin 1 expression by fluorescence-activated cell sorting (FACS).

RESULTS

GZM and PRF1 gene expression were both reduced in AS patients compared to healthy controls, especially in men. Perforin 1, but not granzyme, protein levels were reduced in AS patient serum. Granzymes were elevated in AS SF, but not in rheumatoid arthritis or osteoarthritis SF. FACS revealed a reduction in granzyme-positive and perforin 1-positive lymphocytes, but not an intrinsic defect in CD8+ T cell granzyme or perforin 1 production. CD8+ T cell frequency was reduced in the blood and increased in the SF of AS patients.

CONCLUSION

Our findings indicate that AS patients have an altered cytotoxic T cell profile. These data suggest that CD8+ T cells with a cytotoxic phenotype are recruited to the joints, where they exhibit an activated phenotype. Thus, a central role for CD8+ T cells in AS may have been overlooked and deserves further study.

Measuring the T-cell down-regulation of TCR-zeta, ZAP-70 and CD28 in arthritis patients: An old tool for new biomarkers

Low T-cell receptor (TCR)/CD28 signaling lymphocytes are expanded in arthritis. We asked whether the down-expression of TCR-related molecules correlates with specific arthritis characteristics and if it has clinical implications. TCR-ZETA, ZAP-70 and CD28 expression was measured by flow cytometry in synovial fluid (SF) and peripheral blood (PB)-derived T cells. In PB, ZETA-downregulation in CD4⁺ CD28⁺ and consequent CD4⁺ CD28lowZETAlow cell expansion correlate with CRP elevation, leukocyte recruitment into SF and, primarily, disease activity (DAS). In some patients, ZETA-downregulation extends to CD8⁺ CD28null and/or CD8⁺ CD28⁺ cells, and this correlates with enhanced leukocyte recruitment, multiple joint involvement, and disability index (HAQ). ZETA-downregulation in CD4⁺ CD28⁺ may also lead to CD4⁺ CD28⁺ ZETAnull cell expansion, which strongly correlates with HAQ. In SF, ZETA-downregulation in CD8⁺ CD28null and consequent CD8⁺ CD28nullZETAlow/null cell expansion correlate with CRP elevation and neutrophilic influx into SF, whereas ZAP-downregulation in CD8⁺ CD28⁺ and consequent CD8⁺ CD28lowZAPlow cell expansion strongly correlate with HAQ and DAS. ZETA-downregulation is preponderant in SF of seronegative arthritides, with seronegative rheumatoid arthritis showing significant down-regulation in CD8⁺ CD28null, and non-rheumatoid arthritides showing significant down-regulation in CD4⁺ CD28⁺ . Altogether, we identified new molecular and cellular biomarkers of arthritis-related T-cell inflammation, useful for assessing arthritis activity, predicting polyarticular progression and functional impairment, characterizing seronegative arthritides, and possibly tailoring immunotherapies.

RUNX3 and T-Bet in Immunopathogenesis of Ankylosing Spondylitis-Novel Targets for Therapy?

Susceptibility to ankylosing spondylitis (AS) is polygenic with more than 100 genes identified to date. These include HLA-B27 and the aminopeptidases (ERAP1, ERAP2, and LNPEPS), which are involved in antigen processing and presentation to T-cells, and several genes (IL23R, IL6R, STAT3, JAK2, IL1R1/2, IL12B, and IL7R) involved in IL23 driven pathways of inflammation. AS is also strongly associated with polymorphisms in two transcription factors, RUNX3 and T-bet (encoded by TBX21), which are important in T-cell development and function. The influence of these genes on the pathogenesis of AS and their potential for identifying drug targets is discussed here.

Features of peripheral CD8+CD57+ lymphocytes in patients with autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is an acquired condition characterized by the presence of autoantibodies recognizing erythrocyte-related antigens. Several components of the immune system are involved in disease pathogenesis. Among them, as for other autoimmune disorders, a role for specific CD8⁺CD57⁺ regulatory cells subset could be hypothesized. We evaluated this lymphocyte subset by flow cytometry in 18 AIHA patients randomly selected in a retrospective population of 29 cases. Secondary forms were observed in 65.5% of cases, whereas frequencies of warm, cold, mixed, and atypical forms were similar. Cold agglutinins and cryoglobulins tested positive in 44.8% and 10.3% of cases, respectively. These patients exhibited a higher frequency of peripheral vascular symptoms (odds ratio = 8.2, p = .04) and complement consumption (odds ratio = 7.2, p = .02). Frequency of CD8⁺CD57⁺ cells resulted significantly higher in AIHA patients than in control group (17.0 ± 15.8% vs 8.2 ± 5.0%, p = .04). Regardless of therapeutic schedule, patients with partial or no response to therapy (8/18) showed higher frequencies of CD8⁺CD57⁺ cells as compared with controls (23.6 ± 21.3% vs 8.9 ± 4.9%, p = .01), whereas 10/18 complete responders (CR) showed lower levels of CD8⁺CD57⁺ cells (11.7 ± 6.9%, p = .11). CR and controls showed similar values (p = .24). This study suggests that monitoring this lymphocyte subset before and after treatment administration might have a prognostic value. Moreover, CD8⁺CD57⁺ cells may represent a possible therapeutic target to restore the normal balance between lymphocyte populations.

Association of the HLA-B27 antigen and the CTLA4 gene CT60/rs3087243 polymorphism with ankylosing spondylitis in Algerian population: A case-control study

Ankylosing spondylitis (AS) is a complex inflammatory disease that represents a major health problem both in Algeria and worldwide. Several lines of evidence support that genetic risk factors play a role in AS etiology and the CTLA4 gene has attracted a considerable attention. In this study, we were interested in evaluating the HLA-B27 frequency and in exploring the CTLA4 gene in a sample of the North African population. The dataset of the current study is composed of 81 patients with AS and 123 healthy controls. All samples were genotyped by TaqMan^® allelic discrimination assay. The genetic risk of the HLA-B27 specificity and the CTLA4/CT60 polymorphism were assessed by odds ratios (OR) with 95% confidence intervals (CI). High spondylitis risk was detected for HLA-B27 allele (OR= 14.62, p = 10^-6 ) in addition to a significant association of the CT60*G allele (OR= 1.89, p = .002). After gender and age stratifications, the association of the CT60*G allele was still significant in females sample (OR= 2.10, p = .001) and when age up to 30 years (OR = 2.21, p = .008). Interestingly, the CT60*G allele revealed an increased spondylitis risk in the B27 negative group (OR= 2.81, p = .006). The present work showed in West Algerian population that the HLA-B27 antigen and the variation in the CTLA4 3'UTR region played an important role in the ankylosing spondylitis susceptibility. The heterogeneity of this disease is deduced by genetic difference found between B27+ and B27- groups.

The shortening telomere length of T lymphocytes maybe associated with hyper‑function in servere aplastic anemia

Severe aplastic anemia (SAA) is a primary disorder of severe bone marrow failure characterizing with extreme pancytopenia and a profound diminution of bone marrow progenitor cells, which is associated with T cell hyper‑function. Abnormal telomere shortening of bone marrow mononuclear cell has been reported in AA, which may lead to genomic instability, and result in cell senescence or apoptosis. Notably, certain studies identfieid that lymphocytes of shortening telomere length have undergone apoptosis escape in autoimmune diseases. In order to investigate the association between telomere lengths and function of T lymphocytes in SAA, the relative telomere lengths (RTLs) of different subtypes of T lymphocytes were investigated by flow‑fluorescent in situ hybridization in 30 patients with SAA and 25 healthy controls. Then the levels of expression of cluster of differentiation 28 (CD28), CD158 and CD70 were measured, which represent the function of T lymphocytes. The apoptosis rate and the cell cycle progression of CD8+T lymphocytes, and the level of secretion interferon‑γ and tumor necrosis factor‑α were also measured. Finally, the correlation between telomere length and these functional events of CD8+T lymphocytes was analyzed in patients with SAA. The results showed that RTLs of CD8+T lymphocytes in SAA were significantly shorter compared with those in controls. Furthermore, in patients with SAA, CD8+T lymphocytes are associated with T cell hyper‑function, which is related to the RTL. Thus, the shorter RTLs of CD8+T lymphocytes in SAA may be associated with hyper‑function of these cells, which contribute to the pathogenesis of SAA.

Distinct aging profiles of CD8+ T cells in blood versus gastrointestinal mucosal compartments

A hallmark of human immunosenescence is the accumulation of late-differentiated memory CD8⁺ T cells with features of replicative senescence, such as inability to proliferate, absence of CD28 expression, shortened telomeres, loss of telomerase activity, enhanced activation, and increased secretion of inflammatory cytokines. Importantly, oligoclonal expansions of these cells are associated with increased morbidity and mortality risk in elderly humans. Currently, most information on the adaptive immune system is derived from studies using peripheral blood, which contains approximately only 2% of total body lymphocytes. However, most lymphocytes reside in tissues. It is not clear how representative blood changes are of the total immune status. This is especially relevant with regard to the human gastrointestinal tract (GALT), a major reservoir of total body lymphocytes (approximately 60%) and an anatomical region of high antigenic exposure. To assess how peripheral blood T cells relate to those in other locations, we compare CD8⁺ T cells from peripheral blood and the GALT, specifically rectosigmoid colon, in young/middle age, healthy donors, focusing on phenotypic and functional alterations previously linked to senescence in peripheral blood. Overall, our results indicate that gut CD8⁺ T cells show profiles suggestive of greater differentiation and activation than those in peripheral blood. Specifically, compared to blood from the same individual, the gut contains significantly greater proportions of CD8⁺ T cells that are CD45RA^- (memory), CD28^-, CD45RA^-CD28⁺ (early memory), CD45RA^-CD28^- (late memory), CD25^-, HLA-DR⁺CD38⁺ (activated) and Ki-67⁺ (proliferating); ex vivo CD3⁺ telomerase activity levels are greater in the gut as well. However, gut CD8⁺ T cells may not necessarily be more senescent, since they expressed significantly lower levels of CD57 and PD-1 on CD45RO⁺ memory cells, and had in vitro proliferative dynamics similar to that of blood cells. Compartment-specific age-effects in this cohort were evident as well. Blood cells showed a significant increase with age in proportion of HLA-DR⁺38⁺, Ki-67⁺ and CD25⁺ CD8⁺ T cells; and an increase in total CD3⁺ex-vivo telomerase activity that approached significance. By contrast, the only age-effect seen in the gut was a significant increase in CD45RA^- (memory) and concurrent decrease in CD45RA⁺CD28⁺ (naïve) CD8⁺ T cells. Overall, these results indicate dynamics of peripheral blood immune senescence may not hold true in the gut mucosa, underscoring the importance for further study of this immunologically important tissue in evaluating the human immune system, especially in the context of chronic disease and aging.

Infusion of umbilical cord mesenchymal stem cells alleviates symptoms of ankylosing spondylitis

The current study evaluated 5 patients with ankylosing spondylitis (AS). Patients received intravenous transfusions of umbilical cord mesenchymal stem cells (uMSCs). All therapeutic and adverse responses were assessed and recorded during uMSC therapy. No severe adverse reactions were observed in any of the patients, although a slight transient fever was observed in 3 patients within 2–6 h of intravenous administration of uMSCs. Following treatment, the Bath Ankylosing Spondylitis Disease Activity and Bath Ankylosing Spondylitis Metrology Indices decreased, however the Bath Ankylosing Spondylitis Functional Index increased. The erythrocyte sedimentation rate in 3 patients was reduced and C-reactive protein levels in 1 patient were markedly reduced. The symptoms of AS were alleviated in all patients. The present study indicates that intravenous transfusion of uMSCs is safe and well tolerated by patients and that it effectively alleviates disease activity and clinical symptoms. In the future, a larger cohort of patients with AS should be recruited to enable the systemic evaluation of uMSC therapy.

Immune and myodegenerative pathomechanisms in inclusion body myositis

Inclusion Body Myositis (IBM) is a relatively common acquired inflammatory myopathy in patients above 50 years of age. Pathological hallmarks of IBM are intramyofiber protein inclusions and endomysial inflammation, indicating that both myodegenerative and inflammatory mechanisms contribute to its pathogenesis. Impaired protein degradation by the autophagic machinery, which regulates innate and adaptive immune responses, in skeletal muscle fibers has recently been identified as a potential key pathomechanism in IBM. Immunotherapies, which are successfully used for treating other inflammatory myopathies lack efficacy in IBM and so far no effective treatment is available. Thus, a better understanding of the mechanistic pathways underlying progressive muscle weakness and atrophy in IBM is crucial in identifying novel promising targets for therapeutic intervention. Here, we discuss recent insights into the pathomechanistic network of mutually dependent inflammatory and degenerative events during IBM.

Association Between Protein Tyrosine Phosphatase Non-Receptor Type 22 (PTPN22) Polymorphisms and Risk of Ankylosing Spondylitis: A Meta-analysis

Background

Ankylosing spondylitis (AS) is a chronic autoimmune disease that involves the imbalance of peripheral tolerance possibly caused by the negative signal of activated T cells. The polymorphisms in the human protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene have been pointed out to be related to the pathogenesis of AS, but conclusions over this issue remain contradictory. We attempted to give a more precise conclusion about the effects of PTPN22 polymorphisms on AS risk by means of a meta-analysis.

Material/Methods

PubMed, Embase, Wanfang, and Chinese National Knowledge Infrastructure (CNKI) were searched for relevant studies published in the English or Chinese language. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated with a fixed- or random-effects model to evaluate the correlation between PTPN22 rs2488457, rs1217414, and rs2476601 polymorphisms and AS susceptibility. Sensitivity analysis was also carried out to detect the stability of the results.

Results

The present meta-analysis showed a positive correlation of both PTPN22 rs2488457 and rs1217414 polymorphisms with AS risk under CC vs. GG, CC + GC vs. GG, CC vs. GC + GG, allele C vs. allele G (OR=1.39, 95% CI=1.04–1.85, P=0.646; OR=1.29, 95% CI=1.03–1.62, P=0.426; OR=1.26, 95% CI=1.02–1.56, P=0.971; OR=1.20, 95% CI=1.05–1.38, P=0.571), and TT vs. CC and TT vs. CT + CC models (OR=3.83, 95% CI=1.11–13.24, P=0.196; OR=3.83, 95% CI=1.09–13.42, P=0.244), respectively.

Conclusions

PTPN22 rs2488457 and rs1217414 polymorphisms may be risk factors for AS occurrence.

Human CD8+ T Cells in Asthma: Possible Pathways and Roles for NK-Like Subtypes

Asthma affects approximately 300 million people worldwide and is the most common chronic lung disease, which usually is associated with bronchial inflammation. Most research has focused upon the role of CD4+ T cells, and relatively few studies have addressed the phenotypic and functional roles of CD8+ T cell types and subtypes. Human NK-like CD8+ T cells may involve cells that have been described as CD8+CD28−, CD8+CD28−CD57+, CD8+CD27−, or CD8+ effector memory (TEM) cells, among other. However, most of the data that are available regarding these various cell types were obtained in murine models did not thoroughly characterize these cells with phenotypically or functionally or did not involve asthma-related settings. Nevertheless, one may conceptualize three principal roles for human NK-like CD8+ T cells in asthma: disease-promoting, regulatory, and/or tissue repair. Although evidence for some of these roles is scarce, it is possible to extrapolate some data from overlapping or related CD8+ T cell phenotypes, with caution. Clearly, further research is warranted, namely in terms of thorough functional and phenotypic characterization of human NK-like CD8+ T cells in human asthma of varying severity.

Skin-Resident Effector Memory CD8+CD28- T Cells Exhibit a Profibrotic Phenotype in Patients with Systemic Sclerosis

Loss of CD28 expression by CD8⁺ T cells occurs with age and during chronic inflammatory conditions. CD8⁺CD28^- T cells are a heterogeneous cell subpopulation whose function ranges from immunosuppressive to effector. Here we analyzed the role of CD8⁺CD28^- T cells in the pathogenesis of systemic sclerosis (SSc), a connective tissue disorder characterized by autoimmunity, vasculopathy, and extensive cutaneous and visceral fibrosis. We show that the frequency of CD8⁺CD28^- T cells is increased in the blood and affected skin of SSc patients, independent of patient age, and correlates with the extent of skin fibrosis. We found that most skin-tropic CD8⁺CD28^- T cells are resident in the skin lesions of patients in the early stage of the disease, exhibit an effector memory phenotype, and present a strong cytolytic activity ex vivo. Skin-resident and circulating SSc CD8⁺CD28^- T cells produce high levels of the profibrotic cytokine IL-13, which induces collagen production by normal and SSc dermal fibroblasts. Thus, our findings indicate that CD8⁺CD28^- T cells represent a pathogenic T-cell subset in SSc and likely play a critical role in the early stage of SSc skin disease.

Convergence of Innate and Adaptive Immunity during Human Aging

Aging is associated with profound changes in the human immune system, a phenomenon referred to as immunosenescence. This complex immune remodeling affects the adaptive immune system and the CD8⁺ T cell compartment in particular, leading to the accumulation of terminally differentiated T cells, which can rapidly exert their effector functions at the expenses of a limited proliferative potential. In this review, we will discuss evidence suggesting that senescent αβCD8⁺ T cells acquire the hallmarks of innate-like T cells and use recently acquired NK cell receptors as an alternative mechanism to mediate rapid effector functions. These cells concomitantly lose expression of co-stimulatory receptors and exhibit decreased T cell receptor signaling, suggesting a functional shift away from antigen-specific activation. The convergence of innate and adaptive features in senescent T cells challenges the classic division between innate and adaptive immune systems. Innate-like T cells are particularly important for stress and tumor surveillance, and we propose a new role for these cells in aging, where the acquisition of innate-like functions may represent a beneficial adaptation to an increased burden of malignancy with age, although it may also pose a higher risk of autoimmune disorders.

The genetic association of RUNX3 with ankylosing spondylitis can be explained by allele-specific effects on IRF4 recruitment that alter gene expression

Objectives

To identify the functional basis for the genetic association of single nucleotide polymorphisms (SNP), upstream of the RUNX3 promoter, with ankylosing spondylitis (AS).

Methods

We performed conditional analysis of genetic association data and used ENCODE data on chromatin remodelling and transcription factor (TF) binding sites to identify the primary AS-associated regulatory SNP in the RUNX3 region. The functional effects of this SNP were tested in luciferase reporter assays. Its effects on TF binding were investigated by electrophoretic mobility gel shift assays and chromatin immunoprecipitation. RUNX3 mRNA levels were compared in primary CD8+ T cells of AS risk and protective genotypes by real-time PCR.

Results

The association of the RUNX3 SNP rs4648889 with AS (p<7.6×10⁻¹⁴) was robust to conditioning on all other SNPs in this region. We identified a 2 kb putative regulatory element, upstream of RUNX3, containing rs4648889. In reporter gene constructs, the protective rs4648889 ‘G’ allele increased luciferase activity ninefold but significantly less activity (4.3-fold) was seen with the AS risk ‘A’ allele (p≤0.01). The binding of Jurkat or CD8+ T-cell nuclear extracts to the risk allele was decreased and IRF4 recruitment was reduced. The AS-risk allele also affected H3K4Me1 histone methylation and associated with an allele-specific reduction in RUNX3 mRNA (p<0.05).

Conclusion

We identified a regulatory region upstream of RUNX3 that is modulated by rs4648889. The risk allele decreases TF binding (including IRF4) and reduces reporter activity and RUNX3 expression. These findings may have important implications for understanding the role of T cells and other immune cells in AS.

The expression of molecule CD28 and CD38 on CD4⁺/CD8⁺ T lymphocytes in thymus and spleen elicited by Schistosoma japonicum infection in mice model

Schistosomiasis caused by human schistosomes such as Schistosoma japonicum (S. japonicum) is considered as an immune-related disease. It was demonstrated that specific cytokine antibodies' response elicited by S. japonicum infection was gradually downregulated with the progress of the disease, resulting in a Th1/Th2 polarization and suppression of immune response. CD28 (cluster of differentiation 28) is one of the proteins expressed on T cells that provide co-stimulatory signals required for T cell activation and survival, and CD38 is an activating marker of T lymphocyte with high expression in many acute or chronic infections. The immune signature of CD28null T cells in the peripheral circulation associates with chronic inflammation in many diseases, such as HIV and CMV infection. In the thymus, CD28 expression on developing thymocytes appears to play a role for their selection, and it synergizes with CD38 to induce apoptosis of DP (double-positive) thymocytes. Few reports about CD28 and CD38 have been published in schistosomiasis. Here, we investigated the dynamic patterns of the expression of molecules CD28 and CD38 on CD4(+)/CD8(+) T lymphocytes of the thymus and spleen in mice model with S. japonicum infection. Our data indicated that at an early period of infection, the frequency of CD8(+)CD28(-) T cell in the spleen decreased significantly, but higher at chronic infection than that in control. However, it demonstrated an increasing trend in the thymus with the progression of infection. The frequency of CD4(+)CD28(-) T cells increased from acute infection in the thymus, while from chronic infection in the spleen. The expression of CD38 on CD8(+) T cells began to increase at 4 weeks post infection both in the thymus and spleen; its elevated expression on CD4(+) T cells emerged at 6 weeks post infection in the thymus and at 10 weeks post infection in the spleen. Praziquantel (PZQ) treatment could partially restore the frequency of CD28(+) T cell of CD4(+) T cells and CD38(+) T cell of CD8(+)/CD4(+) T cells in the spleen and CD38(+) T cell in the thymus. We hypothesized that the reactivation of S. japonicum infection may trigger expansion of CD28(-) T cells and hence mediate systemic inflammation. We speculated that CD8(+)CD28(-) T cell might be involved in immune modulation and CD8(+)CD28(-) T cell may be a crucial part in pathogenesis, which can provide further knowledge of the sophisticated mechanism of immuno-downregulation in schistosomiasis and potential treatment target.

Death Receptor 3 (TNFRSF25) Increases Mineral Apposition by Osteoblasts and Region Specific New Bone Formation in the Axial Skeleton of Male DBA/1 Mice

Objectives. Genome wide association studies identified TNFSF member TNF-like protein 1A (TL1A, TNFSF15) as a potential modulator of ankylosing spondylitis (AS). TL1A is the only confirmed TNFSF ligand of death receptor 3 (DR3, TNFRSF25); however, its role in disease pathology is not characterised. We evaluated DR3's role in controlling osteoblast- (OB-) dependent bone formation in vitro and in vivo. Methods. Osteoprogenitor cells and OB were cultured from male DR3-deficient (DR3(ko)) and wild-type (DR3(wt)) DBA/1 mice. DR3 and RANKL expression were tested by flow cytometry. Alkaline phosphatase and mineralization were quantified. Osteopontin, osteoprotegerin, and pro MMP-9 were measured by ELISA. A fluorescent probe (BoneTag) was used to measure in vivo mineralization in 10-month-old mice. Results. DR3 was expressed on osteoprogenitors and OB from DR3(wt) mice. Alkaline phosphatase, osteopontin, and mineral apposition were significantly elevated in DR3(wt) cultures. Levels of RANKL were comparable whilst osteoprotegerin was significantly increased in DR3(wt) cultures. In vivo incorporation of BoneTag was significantly lower in the thoracic vertebrae of 10-month-old DR3(ko) mice. Conclusions. These data identify new roles for DR3 in regulating OB-dependent bone mineral apposition. They potentially begin to explain the atypical pattern of new bone formation observed in the axial skeleton of grouped, aging DBA/1 mice.

Activation-induced and damage-induced cell death in aging human T cells

In multicellular organisms the proper system functionality is ensured by the balance between cell division, differentiation, senescence and death. This balance is changed during aging. Immunosenescence plays a crucial role in aging and leads to the shrinkage of T cell repertoire and the propensity to apoptosis. The elimination of expanded T cells at the end of immune response is crucial to maintain homeostasis and avoid any uncontrolled inflammation. Resting mature T lymphocytes, when activated via their antigen-specific receptor (TCR) and CD28 co-receptor, start to proliferate and then undergo the so called activation induced cell death (AICD), which mechanistically is triggered by the death receptor and leads to apoptosis. T lymphocytes, like other cells, are also exposed to damage, which can trigger the so called damage-induced cell death (DICD). It was hypothesized that oxidative stress and chronic antigenic load increasing with age reduced lymphocyte susceptibility to DICD and enhanced a proinflamatory status leading to increased AICD. However, data collected so far are inconsistent and does not support this assumption. Systematic and comprehensive studies are still needed for conclusive elucidation of the role of AICD and DICD in human immunosenescence, including the role of autophagy and necroptosis in the processes.

β-cell-specific CD8 T cell phenotype in type 1 diabetes reflects chronic autoantigen exposure

Autoreactive CD8 T cells play a central role in the destruction of pancreatic islet β-cells that leads to type 1 diabetes, yet the key features of this immune-mediated process remain poorly defined. In this study, we combined high-definition polychromatic flow cytometry with ultrasensitive peptide-human leukocyte antigen class I tetramer staining to quantify and characterize β-cell-specific CD8 T cell populations in patients with recent-onset type 1 diabetes and healthy control subjects. Remarkably, we found that β-cell-specific CD8 T cell frequencies in peripheral blood were similar between subject groups. In contrast to healthy control subjects, however, patients with newly diagnosed type 1 diabetes displayed hallmarks of antigen-driven expansion uniquely within the β-cell-specific CD8 T cell compartment. Molecular analysis of selected β-cell-specific CD8 T cell populations further revealed highly skewed oligoclonal T cell receptor repertoires comprising exclusively private clonotypes. Collectively, these data identify novel and distinctive features of disease-relevant CD8 T cells that inform the immunopathogenesis of type 1 diabetes.

Premature senescence of T-cell subsets in axial spondyloarthritis

OBJECTIVE

To investigate the possible occurrence of early thymic failure and premature senescence of naïve and memory T-cells in patients with axial spondyloarthritis (aSpA).

METHODS

Prospective, cross-sectional study of consecutive patients with aSpA (n=51), rheumatoid arthritis (RA, n=51) and healthy controls (HCs, n=50). Demographic, clinical and laboratory parameters were collected in all patients and we isolated naïve (CD45RA(+)) and memory (CD45RO(+)) CD4(+) and CD8(+) T-cell subsets by MACS technology. T-cell receptor rearrangement excision circle (TREC) and telomere length were measured by real-time PCR. We used TRECs as a surrogate for thymus function and telomere length as an indicator of cellular senescence. Telomerase activity was analysed with the Telomeric Repeat Amplification Protocols.

RESULTS

We observed a premature decline of thymic output in patients with aSpA and patients with RA compared with HCs as indicated by a reduction of TREC levels in naive T-cells (aSpA: age adjusted regression coefficient (regcoeff) for CD4(+)CD45RA(+) T-cells -2.566, p=0.023; RA regcoeff=-2.844, p=0.008). Telomere length of all CD4(+) and CD8(+) T-cell subsets was reduced in young patients with aSpA compared with HCs, whereas data for patients with RA were comparable with HCs. Telomerase activity was inversely correlated with telomere length in HCs (correlation coefficient (corcoeff)=-0.532, p<0.001) but not in patients with aSpA (corcoeff=-0.056, p=0.697) and RA (corcoeff=-0.003, p=0.982).

CONCLUSIONS

Our data indicate an age-inappropriate shrinkage of thymic output, an inappropriate shortening of telomeres in young patients with aSpA and an impaired telomerase enzyme in patients with aSpA and RA.

CD28 negative T cells: is their loss our gain?

CD28 is a primary costimulation molecule for T cell activation. However, during the course of activation some T cells lose this molecule and assume a CD28-independent existence. These CD28- T cells are generally antigen-experienced and highly differentiated. CD28- T cells are functionally heterogeneous. Their characteristics vary largely on the context in which they are found and range from having enhanced cytotoxic abilities to promoting immune regulation. Thus, CD28 loss appears to be more of a marker for advanced differentiation regardless of the cytotoxic or regulatory function being conducted by the T cell. CD28- T cells are now being recognized as playing significant roles in several human diseases. Various functional CD28- populations have been characterized in inflammatory conditions, infections and cancers. Of note, the recent introduction of costimulation blockade-based therapies, particularly those that inhibit CD28-B7 interactions, has made CD28 loss particularly relevant for solid organ transplantation. Certain CD28- T cell populations seem to promote allograft tolerance whereas others contribute to alloreactivity and costimulation blockade resistant rejection. Elucidating the interplay between these populations and characterizing the determinants of their ultimate function may have relevance for clinical risk stratification and personal determination of optimal posttransplant immune management.

Effects of Tripterygium glycosides on interleukin-17 and CD4+CD25+CD127low regulatory T-cell expression in the peripheral blood of patients with ankylosing spondylitis

The aim of this study was to investigate the possible mechanisms of action of Tripterygium glycosides (TG) in the treatment of ankylosing spondylitis (AS). In total, 20 patients with active AS received treatment with 20 mg TG tablet (TGT) 3 times per day for 6 weeks. In addition, 20 healthy age- and gender-matched individuals were recruited as the control group. The efficacy measures included the Bath AS disease activity index (BASDAI), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. The serum interleukin (IL)-17 levels were measured using ELISA. The expression of CD4⁺CD25⁺CD127^low regulatory T cells (Tregs) in the peripheral blood was evaluated by flow cytometry. A bivariate correlation analysis was used to determine the association of IL-17 levels with BASDAI, ESR, CRP and CD4⁺CD25⁺CD127^low Tregs in AS patients. Prior to treatment, the BASDAI, ESR and CRP levels in AS patients were found to be elevated compared to those in healthy controls and were significantly reduced following TGT treatment (P<0.05, P<0.05 and P<0.05, respectively). Prior to treatment, the AS patients exhibited significantly higher IL-17 levels compared to those in healthy controls (P<0.05). Following TGT treatment, the IL-17 levels were significantly reduced in AS patients (P<0.01) but were not significantly different in the control subjects (P>0.05). In addition, prior to treatment, the ratio of CD4⁺CD25⁺CD127^low Tregs in AS patients was significantly lower compared to that in healthy controls (P<0.05) and it was significantly increased following TGT treatment (P<0.05). The correlation analysis between the BASDAI, ESR or CRP levels and IL-17 revealed a positive linear correlation (P<0.001, P<0.001 and P<0.01, respectively), whereas CD4⁺CD25⁺CD127^low Tregs were found to be negatively correlated with IL-17 (P<0.01). In conclusion, TGT is efficient for the treatment of AS patients and its mechanism of action may be correlated with the upregulation of CD4⁺CD25⁺CD127^low Tregs and the downregulation of IL-17 in the peripheral blood.

T cell receptor-mediated activation is a potent inducer of macroautophagy in human CD8(+)CD28(+) T cells but not in CD8(+)CD28(-) T cells

A key feature of the aged human immune system is the accumulation of highly differentiated CD8(+)CD28(-) T cells, a phenomenon that negatively influences immune function in the elderly. However, the mechanisms that regulate survival or death of CD8(+)CD28(-) T cells remain incompletely understood. Macroautophagy has been shown to protect cells from unfavorable environmental conditions and extend lifespan of various cells and organisms. In this study, we investigated autophagy in CD8(+)CD28(+) and CD8(+)CD28(-) T cells following T cell receptor (TCR) engagement. We demonstrate that TCR-mediated activation led to a potent induction of autophagy in CD8(+)CD28(+) T cells which was accompanied by an increased activity of the mammalian target of rapamycin complex 1 (mTORC1). This was surprising, as mTORC1 is generally perceived as an inhibitor of autophagy. Inhibition of mTORC1 by rapamycin could still enhance activation-induced autophagy. In contrast, CD8(+)CD28(-) T cells induced autophagy to a significantly lower extent in response to TCR engagement compared to CD8(+)CD28(+) T cells and failed to increase autophagy upon mTORC1 inhibition. In conclusion, we describe for the first time the induction of autophagy in human CD8(+) T cells following TCR engagement and the decreased ability of CD8(+)CD28(-) T cells to induce autophagy, suggesting that they cannot meet the metabolic needs of antigen receptor-mediated activation and are therefore unlikely to survive when confronted by their specific antigens.

Mesenchymal stem cells control alloreactive CD8(+) CD28(-) T cells

CD28/B7 co-stimulation blockade with belatacept prevents alloreactivity in kidney transplant patients. However, cells lacking CD28 are not susceptible to belatacept treatment. As CD8(+) CD28(-) T-cells have cytotoxic and pathogenic properties, we investigated whether mesenchymal stem cells (MSC) are effective in controlling these cells. In mixed lymphocyte reactions (MLR), MSC and belatacept inhibited peripheral blood mononuclear cell (PBMC) proliferation in a dose-dependent manner. MSC at MSC/effector cell ratios of 1:160 and 1:2·5 reduced proliferation by 38·8 and 92·2%, respectively. Belatacept concentrations of 0·1 μg/ml and 10 μg/ml suppressed proliferation by 20·7 and 80·6%, respectively. Both treatments in combination did not inhibit each other's function. Allostimulated CD8(+) CD28(-) T cells were able to proliferate and expressed the cytolytic and cytotoxic effector molecules granzyme B, interferon (IFN)-γ and tumour necrosis factor (TNF)-α. While belatacept did not affect the proliferation of CD8(+) CD28(-) T cells, MSC reduced the percentage of CD28(-) T cells in the proliferating CD8(+) T cell fraction by 45·9% (P = 0·009). CD8(+) CD28(-) T cells as effector cells in MLR in the presence of CD4(+) T cell help gained CD28 expression, an effect independent of MSC. In contrast, allostimulated CD28(+) T cells did not lose CD28 expression in MLR-MSC co-culture, suggesting that MSC control pre-existing CD28(-) T cells and not newly induced CD28(-) T cells. In conclusion, alloreactive CD8(+) CD28(-) T cells that remain unaffected by belatacept treatment are inhibited by MSC. This study indicates the potential of an MSC-belatacept combination therapy to control alloreactivity.

Premature cell senescence and T cell receptor-independent activation of CD8+ T cells in juvenile idiopathic arthritis

OBJECTIVE

CD8+ T cells lacking CD28 were originally reported to be a characteristic feature of juvenile idiopathic arthritis (JIA), but the relevance of these unusual cells to this disease remains to be elucidated. Because of recent evidence that loss of CD28 cells is typical of terminally differentiated lymphocytes, the aim of this study was to examine functional subsets of CD8+ T cells in patients with JIA.

METHODS

Blood and/or waste synovial fluid samples were collected from children with a definite diagnosis of JIA (n = 98). Deidentified peripheral blood (n = 33) and cord blood (n = 13) samples from healthy donors were also collected. CD8+ and CD4+ T cells were screened for novel receptors, and where indicated, bioassays were performed to determine the functional relevance of the identified receptor.

RESULTS

JIA patients had a naive T cell compartment with shortened telomeres, and their entire T cell pool had reduced proliferative capacity. They had an overabundance of CD31+CD28(null) CD8+ T cells, which was a significant feature of oligoarticular JIA (n = 62) as compared to polyarticular JIA (n = 36). CD31+ CD28(null) CD8+ T cells had limited mitotic capacity and expressed high levels of the senescence antigens histone γH2AX and/or p16. Ligation of CD31, which was independent of the T cell receptor (TCR), sufficiently induced tyrosine phosphorylation, vesicle exocytosis, and production of interferon-γ and interleukin-10.

CONCLUSION

These data provide the first evidence of cell senescence, as represented by CD31+CD28(null) CD8+ T cells, in the pathophysiology of JIA. Activation of these unusual cells in a TCR-independent manner suggests that they are maladaptive and could be potential targets for immunotherapy.

Association study of polymorphisms rs4552569 and rs17095830 and the risk of ankylosing spondylitis in a Taiwanese population

Ankylosing spondylitis (AS) is a chronic inflammation of the sacroiliac joints, spine and peripheral joints. However, the development of anklosing spondylitis is unclear. Human leukocyte antigens HLA-B27 and ERAP1 have been widely reported to be associated with AS susceptibility. A recent genome-wide association study (GWAS) showed that two new susceptibility loci between EDIL3 and HAPLN1 at 5q14.3 (rs4552569) and within ANO6 at 12q12 (rs17095830) contribute to the risk of AS in Han Chinese. In this study, we enrolled 475 AS patients and 475 healthy subjects to assess whether these genetic variations contribute to the susceptibility and the severity of AS in the Taiwanese population. The correlation between genetic polymorphisms, AS activity indexes, (namely, BASDAI, BASFI and BAS-G) and AS complications (uveitis and inflammatory bowel disease) were tested using the markers, rs4552569 and rs17095830. Although no association between rs4552569/rs17095830 genetic polymorphisms and AS susceptibility/severity was found, a significant association between rs17095830 and inflammatory bowel disease was observed in a Taiwanese population.

Memory T cells in the chronic inflammatory microenvironment of nasal polyposis are hyporesponsive to signaling through the T cell receptor

A majority of T cells from chronic inflammatory tissues derived from patients with nasal polyposis were found to express an effector memory phenotype. We report here that these memory T cells failed to activate NF-κB in response to TCR stimulation but responded normally when the proximal TCR signaling molecules were bypassed with PMA and ionomycin. The dysfunction of these cells was associated with a decrease in the phosphorylation of several TCR proximal signaling molecules including ZAP70, Lck and SLP-76. In addition to the disruption in the TCR signaling pathway, the nasal polyp-associated T cells were shown to have a defect in their ability to translocate LAMP-1 to the cell surface. The results presented here establish that the phenotype and anergy of the T cells in the nasal polyp are similar to those which is seen in memory T cells derived from human tumors and other sites of chronic inflammation.

Immunosenescence and Challenges of Vaccination against Influenza in the Aging Population

Influenza is an important contributor to morbidity and mortality worldwide. Accumulation of genetic mutations termed antigenic drift, allows influenza viruses to inflict yearly epidemics that may result in 250,000 to 500,000 deaths annually. Over 90% of influenza-related deaths occur in the older adult population. This is at least in part a result of increasing dysregulation of the immune system with age, termed immunosenescence. This dysregulation results in reduced capacity to cope with infections and decreased responsiveness to vaccination. The older adult population is in dire need of improved vaccines capable of eliciting protective responses in the face of a waning immune system. This review focuses on the status of immunity, responses to influenza vaccination, and strategies that are currently being explored to elicit enhanced immune responses in this high risk population.

Role of CD8 T Cell Replicative Senescence in Human Aging and in HIV-mediated Immunosenescence

As humans age, their immune systems undergo a process known as immunosenescence. This global aging of the immune system is associated with increased susceptibility to infectious diseases and cancer, reduced effectiveness of vaccination, increased autoimmune phenomena, and tissue damage due to dysregulated inflammation. One hallmark feature of immunosenescence is the accumulation of late-differentiated memory CD8 T cells with features of replicative senescence, such as inability to proliferate, absence of CD28 expression, shortened telomeres, loss of telomerase activity, and enhanced secretion of inflammatory cytokines. The proportion of senescent CD8 T cells increases progressively with age, and often consists of oligoclonal populations that are specific for cytomegalovirus (CMV) antigens. In addition, there is evidence that senescent memory CD8 T cells acquire suppressive functions and may also contribute to carcinogenesis. Chronic HIV disease, even when controlled through antiretroviral therapy (ART), is associated with accelerated immunosenescence, as evidenced by the higher numbers of senescent memory CD8 T cells and increased inflammatory milieu. Interestingly, even in HIV disease, a high proportion of late-differentiated, putatively senescent, memory CD8 T cells are specific for CMV antigens. As in age-related immunosenescence, these HIV-associated changes result in dysregulated immunity, chronic diseases linked to inflammatory damage, and increased morbidity and mortality. This review explores the evidence for CD8 T cell replicative senescence in vitro and in vivo, in the context of both chronological aging and HIV-mediated immunosenescence. We also highlight an important gap in our understanding of human immunosenescence, since all the studies to date have focused on peripheral blood, which contains a minority of the total body lymphocyte population.

Adaptive immunity in ankylosing spondylitis: phenotype and functional alterations of T-cells before and during infliximab therapy

Our aim was to assess the phenotype of T-cell subsets in patients with ankylosing spondylitis (AS), a chronic inflammatory rheumatic disease. In addition, we also tested short-term T-cell activation characteristics. Measurements were done in 13 AS patients before and during the intravenous therapy with anti-TNF agent infliximab (IFX). Flow cytometry was used to determine T-cell subsets in peripheral blood and their intracellular signaling during activation. The prevalence of Th2 and Th17 cells responsible for the regulation of adaptive immunity was higher in AS than in 9 healthy controls. Although IFX therapy improved patients' condition, immune phenotype did not normalize. Cytoplasmic and mitochondrial calcium responses of CD4+ and CD8+ cells to a specific activation were delayed, while NO generation was increased in AS. NO generation normalized sooner upon IFX than calcium response. These results suggest an abnormal immune phenotype with functional disturbances of CD4+ and CD8+ cells in AS.

Persistent viral infections and immune aging

Immunosenescence comprises a set of dynamic changes occurring to both, the innate as well as the adaptive immune system that accompany human aging and result in complex manifestations of still poorly defined deficiencies in the elderly population. One of the most prominent alterations during aging is the continuous involution of the thymus gland which is almost complete by the age of 50. Consequently, the output of naïve T cells is greatly diminished in elderly individuals which puts pressure on homeostatic forces to maintain a steady T cell pool for most of adulthood. In a great proportion of the human population, this fragile balance is challenged by persistent viral infections, especially Cytomegalovirus (CMV), that oblige certain T cell clones to monoclonally expand repeatedly over a lifetime which then occupy space within the T cell pool. Eventually, these inflated memory T cell clones become exhausted and their extensive accumulation accelerates the age-dependent decline of the diversity of the T cell pool. As a consequence, infectious diseases are more frequent and severe in elderly persons and immunological protection following vaccination is reduced. This review therefore aims to shed light on how various types of persistent viral infections, especially CMV, influence the aging of the immune system and highlight potential measures to prevent the age-related decline in immune function.

CD8+ CD28- and CD8+ CD57+ T cells and their role in health and disease

Chronic antigenic stimulation leads to gradual accumulation of late-differentiated, antigen-specific, oligoclonal T cells, particularly within the CD8(+) T-cell compartment. They are characterized by critically shortened telomeres, loss of CD28 and/or gain of CD57 expression and are defined as either CD8(+) CD28(-) or CD8(+) CD57(+) T lymphocytes. There is growing evidence that the CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population plays a significant role in various diseases or conditions, associated with chronic immune activation such as cancer, chronic intracellular infections, chronic alcoholism, some chronic pulmonary diseases, autoimmune diseases, allogeneic transplantation, as well as has a great influence on age-related changes in the immune system status. CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population is heterogeneous and composed of various functionally competing (cytotoxic and immunosuppressive) subsets thus the overall effect of CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell-mediated immunity depends on the predominance of a particular subset. Many articles claim that CD8(+) CD28(-) (CD8(+) CD57(+)) T cells have lost their proliferative capacity during process of replicative senescence triggered by repeated antigenic stimulation. However recent data indicate that CD8(+) CD28(-) (CD8(+) CD57(+)) T cells can transiently up-regulate telomerase activity and proliferate under certain stimulation conditions. Similarly, conflicting data is provided regarding CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell sensitivity to apoptosis, finally leading to the conclusion that this T-cell population is also heterogeneous in terms of its apoptotic potential. This review provides a comprehensive approach to the CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population: we describe in detail its origins, molecular and functional characteristics, subsets, role in various diseases or conditions, associated with persistent antigenic stimulation.

Gain and loss of T cell subsets in old age--age-related reshaping of the T cell repertoire

The immune system is affected by the aging process and undergoes significant age-related changes, termed immunosenescence. Different T cell subsets are affected by this process. Alterations within the bone marrow and thymus lead to a shift in the composition of the T cell repertoire from naïve to antigen-experienced T cells, thereby compromising the diversity of the T cell pool. Additional infection with latent pathogens such as cytomegalovirus aggravates this process. In this review, we focus on the major age-related changes that occur in the naïve and the antigen-experienced T cell population. We discuss the mechanisms responsible for the generation and maintenance of these subsets and how age-related changes can be delayed or prevented by clinical interventions.

Individual characterization of stably expanded T cell clones in ankylosing spondylitis patients

Ankylosing spondylitis (AS) is commonly characterized by clonal expansions of T cells. However, these clonal populations are poorly studied and their role in disease initiation and progression remains unclear. Here, we performed mass sequencing of TCR V beta libraries to search for the expanded T cell clones for two AS patients. A number of clones comprising more than 5% of the corresponding TCR V beta family were identified in both patients. For the first time, expanded clones were shown to be stably abundant in blood samples of AS patients for the prolonged period (1.5 and 2.5 years for two patients, correspondingly). These clones were individually characterized in respect to their differentiation status using fluorescent cell sorting with CD27, CD28, and CD45RA markers followed by quantitative identification of each clone within corresponding fraction using real time PCR analysis. Stable clones differed in phenotype and several were shown to belong to the proinflammatory CD27 - /CD28 - population. Their potentially cytotoxic status was confirmed by staining with perforin-specific antibodies. Search for the TCR V beta CRD3 sequences homologous to the identified clones revealed close matches with the previously reported T cell clones from AS and reactive arthritis patients, thus supporting their role in the disease and proposing consensus TCR V beta CDR3 motifs for AS. Interestingly, these motifs were also found to have homology with earlier reported virus-specific CDR3 variants, indicating that viral infections could play role in development of AS.