Prevalence, clinical relevance and characterization of circulating cytotoxic CD4+CD28- T cells in ankylosing spondylitis

Enhanced Type 1 Interferon Signature in Axial Spondyloarthritis Patients Unresponsive to Secukinumab Treatment

OBJECTIVE

Axial spondyloarthritis (axSpA) is an inflammatory disease in which overactive interleukin (IL)-17A-producing cells are implicated in a central role. Therapeutically, biologics that target IL-17A, such as secukinumab, have demonstrated improved clinical outcomes. Despite this translational success, there is a gap in understanding why some patients with axSpA do not respond to IL-17A-blocking therapy. Our study aims to discriminate immune profiles between secukinumab responders (SEC-R) and nonresponders (SEC-NR).

METHODS

Peripheral blood mononuclear cells were collected from 30 patients with axSpA before and 24 weeks after secukinumab treatment. Frequency of CD4+ subsets were compared between SEC-R and SEC-NR using flow cytometry. Mature CD45RO+CD45RA-CD4+ T cells were fluorescent-activated cell sorting sorted, and RNA was measured using NanoString analysis.

RESULTS

SEC-NR had an increased frequency of IL-17A-producing RORγt+CD4+ T cells compared to healthy controls before secukinumab treatment (P < 0.01). SEC-NR had a significant increase of CXCR3+ CD4+ T cells before secukinumab treatment compared to SEC-R (P < 0.01). Differentially expressed gene analysis revealed up-regulation of type 1 interferon (IFN)-regulated genes in SEC-NR patients compared to SEC-R patients after receiving the biologic. SEC-R patients had an up-regulated cytotoxic CD4+ T cell gene signature before receiving secukinumab treatment compared to SEC-NR patients.

CONCLUSION

The increased frequency of IL-17A-producing cells in SEC-NR patients suggests a larger inflammatory burden than SEC-R patients. With treatment, SEC-NR patients have a more pronounced type 1 IFN signature than SEC-R patients, suggesting a mechanism contributing to this larger inflammatory burden. The results point toward more immune heterogeneity in axSpA than has been recognized and highlights the need for precision therapeutics in this disease.

Regulatory T cells in spondyloarthropathies: genetic evidence, functional role, and therapeutic possibilities

Regulatory T cells (Tregs) are a very specialized subset of T lymphocytes: their main function is controlling immune responses during inflammation. T-regs involvement in autoimmune and immune-mediated rheumatic diseases is well-described. Here, we critically review the up-to-date literature findings on the role of Tregs in spondyloarthropathies, particularly in ankylosing spondylitis (AS), a polygenic inflammatory rheumatic disease that preferentially affects the spine and the sacroiliac joints. Genetics discoveries helped in elucidating pathogenic T-regs gene modules and functional involvement. We highlight T-regs tissue specificity as crucial point, as T-regs might have a distinct epigenomic and molecular profiling depending on the different site of tissue inflammation. Furthermore, we speculate about possible therapeutic interventions targeting, or enhancing, Treg cells in spondyloarthropathies.

CD4 T cells in chronic myeloid leukemia present MHC class II-dependent and IFN-γ-dependent cytotoxic capacity

At present, many therapeutic schemes have been used to improve the prognosis of patients with chronic myeloid leukemia (CML), but response remains poor in a small group of patients. CD4 T cell-mediated cytotoxicity has been found in various autoimmune diseases. This study analyzed the characteristics of CD4 T cell mediated cytotoxicity in CML patients and healthy people. The cytotoxicity of CD4 T cells was tested in using two CML cell lines, including the MHC class II-deficient K562 cells and the MHC class II-expressing KU812 cells. CD4 T cell-mediated lysis was minimal in K562 cells but was much higher in KU812 cells. In CML patients, the level of CD4 T cell-mediated lysis was limited to a certain level. Interestingly, pre-treating KU812 cells with IFN-γ could significantly elevate the expression of MHC class II and elevate the level of CD4 T cell-mediated lysis. Overall, these data indicated CD4 T cells could become a potential candidate for cytotoxic elimination of CML cells.

Low perforin expression in CD8+ T lymphocytes during the acute phase of severe SARS-CoV-2 infection predicts long COVID

T cell cytotoxicity plays a major role in antiviral immunity. Anti-SARS-CoV-2 immunity may determine acute disease severity, but also the potential persistence of symptoms (long COVID). We therefore measured the expression of perforin, a cytotoxic mediator, in T cells of patients recently hospitalized for SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to Intensive Care Units (ICUs) or non-ICU, and 29 age- and sex-matched healthy controls (HCs). Amounts of intracellular perforin and granzyme-B, as well as cell surface expression of the degranulation marker CD107A were determined by flow cytometry. The levels of 15 cytokines in plasma were measured by Luminex. The frequency of perforin-positive T4 cells and T8 cells was higher in patients than in HCs (9.9 ± 10.1% versus 4.6 ± 6.4%, p = 0.006 and 46.7 ± 20.6% vs 33.3 ± 18.8%, p = 0.004, respectively). Perforin expression was neither correlated with clinical and biological markers of disease severity nor predictive of death. By contrast, the percentage of perforin-positive T8 cells in the acute phase of the disease predicted the onset of long COVID one year later. A low T8 cytotoxicity in the first days of SARS-CoV-2 infection might favor virus replication and persistence, autoimmunity, and/or reactivation of other viruses such as Epstein-Barr virus or cytomegalovirus, paving the way for long COVID. Under this hypothesis, boosting T cell cytotoxicity during the acute phase of the infection could prevent delayed sequelae.

The Era of Cytotoxic CD4 T Cells

In 1986, Mosmann and Coffman identified 2 functionally distinct subsets of activated CD4 T cells, Th1 and Th2 cells, being key in distinct T cell mediated responses. Over the past three decades, our understanding of CD4 T cell differentiation has expanded and the initial paradigm of a dichotomic CD4 T cell family has been revisited to accommodate a constantly growing number of functionally distinct CD4 T helper and regulatory subpopulations. Of note, CD4 T cells with cytotoxic functions have also been described, initially in viral infections, autoimmune disorders and more recently also in cancer settings. Here, we provide an historical overview on the discovery and characterization of cytotoxic CD4 T cells, followed by a description of their mechanisms of cytotoxicity. We emphasize the relevance of these cells in disease conditions, particularly in cancer, and we provide insights on how to exploit these cells in immunotherapy.

CD4+ Cytotoxic T cells - Phenotype, Function and Transcriptional Networks Controlling Their Differentiation Pathways

The two major subsets of peripheral T cells are classically divided into the CD4⁺ T helper cells and the cytotoxic CD8⁺ T cell lineage. However, the appearance of some effector CD4⁺ T cell populations displaying cytotoxic activity, in particular during viral infections, has been observed, thus breaking the functional dichotomy of CD4⁺ and CD8⁺ T lymphocytes. The strong association of the appearance of CD4⁺ cytotoxic T lymphocytes (CD4 CTLs) with viral infections suggests an important role of this subset in antiviral immunity by controlling viral replication and infection. Moreover, CD4 CTLs have been linked with anti-tumor activity and might also cause immunopathology in autoimmune diseases. This raises interest into the molecular mechanisms regulating CD4 CTL differentiation, which are poorly understood in comparison to differentiation pathways of other Th subsets. In this review, we provide a brief overview about key features of CD4 CTLs, including their role in viral infections and cancer immunity, and about the link between CD4 CTLs and immune-mediated diseases. Subsequently, we will discuss the current knowledge about transcriptional and epigenetic networks controlling CD4 CTL differentiation and highlight recent data suggesting a role for histone deacetylases in the generation of CD4 CTLs.

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.

Human CD4+ T-Cell Clone Expansion Leads to the Expression of the Cysteine Peptidase Inhibitor Cystatin F

The existence of CD4+ cytotoxic T cells (CTLs) at relatively high levels under different pathological conditions in vivo suggests their role in protective and/or pathogenic immune functions. CD4+ CTLs utilize the fundamental cytotoxic effector mechanisms also utilized by CD8+ CTLs and natural killer cells. During long-term cultivation, CD4+ T cells were also shown to acquire cytotoxic functions. In this study, CD4+ human T-cell clones derived from activated peripheral blood lymphocytes of healthy young adults were examined for the expression of cytotoxic machinery components. Cystatin F is a protein inhibitor of cysteine cathepsins, synthesized by CD8+ CTLs and natural killer cells. Cystatin F affects the cytotoxic efficacy of these cells by inhibiting the major progranzyme convertases cathepsins C and H as well as cathepsin L, which is involved in perforin activation. Here, we show that human CD4+ T-cell clones express the cysteine cathepsins that are involved in the activation of granzymes and perforin. CD4+ T-cell clones contained both the inactive, dimeric form as well as the active, monomeric form of cystatin F. As in CD8+ CTLs, cysteine cathepsins C and H were the major targets of cystatin F in CD4+ T-cell clones. Furthermore, CD4+ T-cell clones expressed the active forms of perforin and granzymes A and B. The levels of the cystatin F decreased with time in culture concomitantly with an increase in the activities of granzymes A and B. Therefore, our results suggest that cystatin F plays a role in regulating CD4+ T cell cytotoxicity. Since cystatin F can be secreted and taken up by bystander cells, our results suggest that CD4+ CTLs may also be involved in regulating immune responses through cystatin F secretion.

Premature Senescence of T-cells Favors Bone Loss During Osteolytic Diseases. A New Concern in the Osteoimmunology Arena

Cellular senescence is a biological process triggered in response to time-accumulated DNA damage, which prioritizes cell survival over cell function. Particularly, senescent T lymphocytes can be generated prematurely during chronic inflammatory diseases regardless of chronological aging. These senescent T lymphocytes are characterized by the loss of CD28 expression, a co-stimulatory receptor that mediates antigen presentation and effective T-cell activation. An increased number of premature senescent CD4+CD28- T lymphocytes has been frequently observed in osteolytic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, osteopenia, osteoporosis, and osteomyelitis. Indeed, CD4+CD28- T lymphocytes produce higher levels of osteoclastogenic molecular mediators directly related to pathologic bone loss, such as tumor necrosis factor (TNF)-α, interleukin (IL)-17A, and receptor-activator of nuclear factor κB ligand (RANKL), as compared with regular CD4+CD28+ T lymphocytes. In addition, premature senescent CD8+CD28- T lymphocytes have been negatively associated with bone healing and regeneration by inhibiting osteoblast differentiation and mesenchymal stromal cell survival. Therefore, accumulated evidence supports the role of senescent T lymphocytes in osteoimmunology. Moreover, premature senescence of T-cells seems to be associated with the functional imbalance between the osteolytic T-helper type-17 (Th17) and bone protective T regulatory (Treg) lymphocytes, as well as the phenotypic instability of Treg lymphocytes responsible for its trans-differentiation into RANKL-producing exFoxp3Th17 cells, a key cellular phenomenon directly related to bone loss. Herein, we present a framework for the understanding of the pathogenic characteristics of T lymphocytes with a premature senescent phenotype; and particularly, we revise and discuss their role in the osteoimmunology of osteolytic diseases.

Impact of Immunotherapy on CD4 T Cell Phenotypes and Function in Cancer

Immunotherapy has become a standard treatment in many cancers and it is based on three main therapeutic axes: immune checkpoint blockade (ICB), vaccination and adoptive cell transfer (ACT). If originally these therapies mainly focused on exploiting CD8 T cells given their role in the direct elimination of tumor cells, increasing evidence highlights the crucial role CD4 T cells play in the antitumor immune response. Indeed, these cells can profoundly modulate the tumor microenvironment (TME) by secreting different types of cytokine or by directly eliminating cancer cells. In this review, we describe how different CD4 T cell subsets can contribute to tumor immune responses during immunotherapy and the novel high-throughput immune monitoring tools that are expected to facilitate the study of CD4 T cells, at antigen-specific and single cell level, thus accelerating bench-to-bed translational research in cancer.

Lymphopenia in primary Sjögren's syndrome is associated with premature aging of naïve CD4+ T cells

OBJECTIVE

To investigate peripheral lymphopenia, a frequent finding in primary Sjögren's syndrome (pSS) associated with higher disease activity and increased mortality.

METHODS

Prospective, cross-sectional study of consecutive patients with pSS (n = 66) and healthy controls (n = 181). Lymphocyte subsets were analysed by flow cytometry, naïve (CD45RA+) and memory (CD45RO+) CD4+ T cells were purified by MACS technology. In vitro proliferation and senescence-associated β-galactosidase (SABG) were assessed by flow cytometry. Telomere length and TCR excision circles (TREC) were measured by real-time PCR. Telomerase activity was analysed according to the telomeric repeat amplification protocols (TRAP).

RESULTS

In pSS, lymphopenia mainly affected naïve CD4+ T cells. We noted a lower frequency of proliferating naïve CD4+ T cells ex vivo and decreased homeostatic proliferation in response to IL-7 stimulation in vitro. Furthermore, naïve CD4+ T cells exhibited signs of immune cell aging including shortened telomeres, a reduction in IL-7R expression and accumulation of SABG. The senescent phenotype could be explained by telomerase insufficiency and drastically reduced levels of T-cell receptor excision circles (TRECs), indicating a history of extensive post-thymic cell division. TRECs correlated with the number of naïve CD4+ T cells linking the extend of earlier proliferation to the inability to sustain normal cell numbers.

CONCLUSION

In pSS, evidence for increased proliferation of naïve CD4+ T cells earlier in life is associated with a senescent phenotype unable to sustain homeostasis. The lack of naïve CD4+ T cells forms the basis of lymphopenia frequently observed in pSS.

Tumor-specific cytolytic CD4 T cells mediate immunity against human cancer

CD4 T cells have been implicated in cancer immunity for their helper functions. Moreover, their direct cytotoxic potential has been shown in some patients with cancer. Here, by mining single-cell RNA-seq datasets, we identified CD4 T cell clusters displaying cytotoxic phenotypes in different human cancers, resembling CD8 T cell profiles. Using the peptide-MHCII-multimer technology, we confirmed ex vivo the presence of cytolytic tumor-specific CD4 T cells. We performed an integrated phenotypic and functional characterization of these cells, down to the single-cell level, through a high-throughput nanobiochip consisting of massive arrays of picowells and machine learning. We demonstrated a direct, contact-, and granzyme-dependent cytotoxic activity against tumors, with delayed kinetics compared to classical cytotoxic lymphocytes. Last, we found that this cytotoxic activity was in part dependent on SLAMF7. Agonistic engagement of SLAMF7 enhanced cytotoxicity of tumor-specific CD4 T cells, suggesting that targeting these cells might prove synergistic with other cancer immunotherapies.

Association of MICA-129Met/Val polymorphism with clinical outcome of anti-TNF therapy and MICA serum levels in patients with rheumatoid arthritis

MHC class I polypeptide-related sequence A (MICA) is a stress-induced protein involved in activation of NK and T cells through interaction with NKG2D receptor. These molecules are atypically expressed in synovium of patients diagnosed with rheumatoid arthritis (RA). A total of 279 patients with RA, qualified to TNF-blockade therapy, were genotyped for MICA rs1051792 SNP. The effectiveness of anti-TNF agents was assessed with European League Against Rheumatism criteria. Significant relationship between MICA rs1051792 and outcome of TNF-blockade therapy has been found. The MICA rs1051792 GG genotype was overrepresented in patients non-responsive to anti-TNF drugs in comparison with other genotypes (p = 0.010). On the other hand, beneficial therapeutic response was more frequently detected among RA subjects possessing heterozygous genotype than those with homozygous genotypes (p = 0.003). Furthermore, increased MICA concentrations in serum were observed in patients possessing MICA rs1051792 GG genotype as compared with those with GA or AA genotypes (p = 1.8 × 10^-5). The results from this study indicate the potential influence of MICA rs1051792 polymorphism on modulation of therapeutic response to TNF-blockade treatment in RA.

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.

IL-10 signaling prevents gluten-dependent intraepithelial CD4+ cytotoxic T lymphocyte infiltration and epithelial damage in the small intestine

Breach of tolerance to gluten leads to the chronic small intestinal enteropathy celiac disease. A key event in celiac disease development is gluten-dependent infiltration of activated cytotoxic intraepithelial lymphocytes (IELs), which cytolyze epithelial cells causing crypt hyperplasia and villous atrophy. The mechanisms leading to gluten-dependent small intestinal IEL infiltration and activation remain elusive. We have demonstrated that under homeostatic conditions in mice, gluten drives the differentiation of anti-inflammatory T cells producing large amounts of the immunosuppressive cytokine interleukin-10 (IL-10). Here we addressed whether this dominant IL-10 axis prevents gluten-dependent infiltration of activated cytotoxic IEL and subsequent small intestinal enteropathy. We demonstrate that IL-10 regulation prevents gluten-induced cytotoxic inflammatory IEL infiltration. In particular, IL-10 suppresses gluten-induced accumulation of a specialized population of cytotoxic CD4⁺CD8αα⁺ IEL (CD4⁺ CTL) expressing Tbx21, Ifng, and Il21, and a disparate non-cytolytic CD4⁺CD8α^- IEL population expressing Il17a, Il21, and Il10. Concomitantly, IL-10 suppresses gluten-dependent small intestinal epithelial hyperproliferation and upregulation of stress-induced molecules on epithelial cells. Remarkably, frequencies of granzyme B⁺CD4⁺CD8α⁺ IEL are increased in pediatric celiac disease patient biopsies. These findings demonstrate that IL-10 is pivotal to prevent gluten-induced small intestinal inflammation and epithelial damage, and imply that CD4⁺ CTL are potential new players into these processes.

Involvement of CD8+ T cell subsets in early response to vascular injury in patients with peripheral artery disease in vivo

AIMS

Adaptive immunity is critical in vascular remodelling following arterial injury. We hypothesized that acute changes in T cells at a percutaneous transluminal angioplasty (PTA) site could serve as an index of their potential interaction with the injured vascular wall.

METHODS AND RESULTS

T cell subsets were characterised in 45 patients with Rutherford 3-4 peripheral artery disease (PAD) undergoing PTA. Direct angioplasty catheter blood sampling was performed before and immediately after the procedure. PTA was associated with an acute reduction of α/β-TcR CD8+ T cells. Further characterisation revealed significant reduction in pro-atherosclerotic CD28nullCD57+ T cells, effector (CD45RA+CCR7-) and effector memory (CD45RA-CCR7-) cells, in addition to cells bearing activation (CD69, CD38) and tissue homing/adhesion markers (CD38, CCR5).

CONCLUSIONS

The acute reduction observed here is likely due to the adhesion of cells to the injured vascular wall, suggesting that immunosenescent, activated effector CD8+ cells have a role in the early vascular injury immune response following PTA in PAD patients.

The NKG2D/NKG2DL Axis in the Crosstalk Between Lymphoid and Myeloid Cells in Health and Disease

Natural killer group 2, member D (NKG2D) receptor is a type II transmembrane protein expressed by both innate and adaptive immune cells, including natural killer (NK) cells, CD8+ T cells, invariant NKT cells, γδ T cells, and some CD4+ T cells under certain pathological conditions. NKG2D is an activating NK receptor that induces cytotoxicity and production of cytokines by effector cells and supports their proliferation and survival upon engagement with its ligands. In both innate and T cell populations, NKG2D can costimulate responses induced by other receptors, such as TCR in T cells or NKp46 in NK cells. NKG2D ligands (NKG2DLs) are remarkably diverse. Initially, NKG2DL expression was typically attributed to stressed, infected, or transformed cells, thus signaling “dysregulated-self.” However, many reports indicated their expression under homeostatic conditions, usually in the context of cell activation and/or proliferation. Myeloid cells, including macrophages and dendritic cells (DCs), are among the first cells sensing and responding to pathogens and tissue damage. By secreting a plethora of soluble mediators, by presenting antigens to T cells and by expressing costimulatory molecules, myeloid cells play vital roles in inducing and supporting responses of other immune cells in lymphoid organs and tissues. When activated, both macrophages and DCs upregulate NKG2DLs, thereby enabling them with additional mechanisms for regulating lymphocyte responses. In this review, we will focus on the expression of NKG2D by innate and adaptive lymphocytes, the regulation of NKG2DL expression on myeloid cells, and the contribution of the NKG2D/NKG2DL axis to the crosstalk of myeloid cells with NKG2D-expressing lymphocytes. In addition, we will highlight pathophysiological conditions associated with NKG2D/NKG2DL dysregulation and discuss the putative involvement of the NKG2D/NKG2DL axis in the lymphocyte/myeloid cell crosstalk in these diseases.

Age determines response to anti-TNFα treatment in patients with ankylosing spondylitis and is related to TNFα-producing CD8 cells

Younger age is a predictor of good clinical response to treatment with tumour necrosis factor (TNF) α inhibitors in ankylosing spondylitis (AS) patients; therefore, the aim of the study was to determine age-related differences in cellular functions, which can predict the response. High disease activity AS patients were treated with TNFα inhibitors for 12 weeks. Based on the percentage of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) improvement, patients were divided into responding or non-responding groups. Cytometric and clinical assessment were determined at baseline, 4, and 12 weeks after initiation of anti-TNFα treatment. Expression of activation markers on T cells and intracellular cytokine staining was performed. Baseline percentage of TNFα-producing CD8 cells was lower in responders than in non-responders (20.8 ± 2.9 vs 40.7 ± 8.2; P = 0.04 in T test) and increased in the responding group during the first month of treatment (20.8 ± 2.9 vs 30.3 ± 2.5; P = 0.02). Moreover, its baseline level correlated with age (r = 0.7; P = 0.0009) but not with BASDAI improvement adjusted for age. There were no differences in the baseline percentage of IL-4, IL-17A, and IFNγ within CD4 and CD8 cells nor in the expression of CD25, CD28, and CD69 on these cells between responders and non-responders. However, baseline level of CD4+CD28null cells correlated with the percentage of BASDAI improvement while analysed as a continuous variable adjusted for age (r = − 0.4; P = 0.048). Clinical predictors of response were also determined. Influence of age on the response to anti-TNFα treatment in AS patients could be mediated by TNFα-producing CD8 cells.

Rationale and Design of the ARREST Trial Investigating Mesenchymal Stem Cells in the Treatment of Small Abdominal Aortic Aneurysm

BACKGROUND

Abdominal aortic aneurysms (AAAs) are a major source of morbidity and mortality despite continuing advances in surgical technique and care. Although the inciting factors for AAA development continue to be elusive, accumulating evidence suggests a significant periaortic inflammatory response leading to degradation and dilation of the aortic wall. Previous human trials have demonstrated safety and efficacy of mesenchymal stem cells (MSCs) in the treatment of inflammation-related pathologies such as rheumatoid arthritis, graft versus host disease, and transplant rejection. Therefore, herein, we describe the Aortic Aneurysm Repression with Mesenchymal Stem Cells (ARREST) trial, a phase I investigation into the safety of MSC infusion for patients with small AAA and the cells' effects on modulation of AAA-related inflammation.

METHODS

ARREST is a phase I, single-center, double-blind, randomized controlled trial (RCT) investigating infusion both dilute and concentrated MSCs compared to placebo in 36 small AAA (35-45 mm) patients. Subjects will be followed by study personnel for 12 months to ascertain incidence of adverse events, immune cell phenotype expression, peripheral cytokine profile, and periaortic inflammation. Maximum transverse aortic diameter will be assessed regularly for 5 years by a combination of computed tomography and duplex sonography.

RESULTS

Four patients have thus far been enrolled, randomized, and treated per protocol. We anticipate the conclusion of the treatment phase within the next 24 months with ongoing long-term follow-up.

CONCLUSIONS

ARREST will be pivotal in assessing the safety of MSC infusion and provide preliminary data on the ability of MSCs to favorably modulate the pathogenic AAA host immune response. The data gleaned from this phase I trial will provide the groundwork for a larger, phase III RCT which may provide the first pharmaceutical intervention for AAA.

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.

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.

Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4⁺CD28^null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4⁺CD28^null T cells. In vivo, we observed de novo formation, as well as expansion of CD4⁺CD28^null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4⁺CD28^null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4⁺CD28^null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4⁺ T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4⁺CD28^null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4⁺CD28^null T cells, thereby boosting the activation of disease-specific CD4⁺ T cells and aggravating autoimmune mediated inflammation and demyelination.

Fighting Viral Infections and Virus-Driven Tumors with Cytotoxic CD4+ T Cells

CD4+ T cells have been and are still largely regarded as the orchestrators of immune responses, being able to differentiate into distinct T helper cell populations based on differentiation signals, transcription factor expression, cytokine secretion, and specific functions. Nonetheless, a growing body of evidence indicates that CD4+ T cells can also exert a direct effector activity, which depends on intrinsic cytotoxic properties acquired and carried out along with the evolution of several pathogenic infections. The relevant role of CD4+ T cell lytic features in the control of such infectious conditions also leads to their exploitation as a new immunotherapeutic approach. This review aims at summarizing currently available data about functional and therapeutic relevance of cytotoxic CD4+ T cells in the context of viral infections and virus-driven tumors.

Milk Casein-Based Diet Containing TGF-β Controls the Inflammatory Reaction in the HLA-B27 Transgenic Rat Model

BACKGROUND

A casein-based formula containing TGF-beta has been successfully used in adolescents during acute episodes of Crohn's disease. The role played by this molecule requires confirmation. We have examined the capacity of a TGF-beta containing diet to control the intestinal inflammation in HLA-B27 transgenic rats, and compared its effects with a similar diet devoid of TGF-beta.

METHODS

Three groups of rats were studied. HLA-B27/hbeta2M transgenic rats were fed with a casein-based rat-adapted diet containing TGF-beta or a control casein-based diet without TGF-beta. Fischer control animals were fed the latter. Body weight, dietary intake, tissue weights, fecal samples, leukocyte counts, and acute phase response were analyzed. Intestinal inflammation was assessed by histology, myeloperoxidase, and mRNA expression of cytokines. MUC2 protein expression was assessed by immunohistochemistry. Breakdown of muscle protein was examined.

RESULTS

The test diet improved diarrhea increasing the fecal dry matter and the colonic inflammation as shown by a lower inflammatory score (2.43 +/- 1.13 vs 4.42 +/- 0.53, p < .05), lower mucosal thickness (431.25 +/- 72.29 vs 508.57 +/- 81.32 microm, p = .08) and decreased IFNgamma mRNA expression. MUC2 protein expression was increased in HLA rats fed the TGF-beta diet compared with HLA rats fed the control diet, but restitution to normal pattern was not observed. The test diet also decreased leukocytosis and the acute phase response and improved the muscle catabolic response.

CONCLUSION

The TGF-beta containing diet has a beneficial effect in an animal model of intestinal inflammation. Our observations support a potential role for dietary TGF-beta in the restoration of immune homeostasis.

CD4+ T cell-mediated cytotoxicity eliminates primary tumor cells in metastatic melanoma through high MHC class II expression and can be enhanced by inhibitory receptor blockade

Metastatic melanoma is a rapidly progressing disease with high mortality rate and limited treatment options. Immunotherapy based on tumor-targeting cytotoxic T cell responses represents a promising strategy. To assist in its development, we examined the possibility and efficacy of using CD4+ cytotoxic T cells. The regulatory mechanisms controlling CD4+ T cell-mediated cytotoxicity were also investigated. We found that naturally occurring granzyme B and perforin-expressing CD4+ cytotoxic T cells can be recovered from metastatic melanoma patients at significantly elevated frequencies compared to those from healthy controls. These CD4+ cytotoxic T cells were also capable of killing autologous tumor cells harvested from metastatic melanoma, independent of CD8+ T cells or any other cell types. However, several restricting factors were observed. First, the cytolytic activity by CD4+ T cells required high MHC class II expression on melanoma cells, which was not satisfied in a subset of melanomas. Second, the granzyme B and perforin release by activated CD4+ cytotoxic T cells was reduced after coculturing with autologous melanoma cells, characterized by low LAMP-1 expression and low granzyme B and perforin secretion in the supernatant. This suggested that inhibitory mechanisms were present to suppress CD4+ cytotoxic T cells. Indeed, blockade of PD-1 and CTLA-4 had increased the cytolytic activity of CD4+ T cells but was only effective in MHC class II high but not MHC class II low melanomas. Together, our study showed that CD4+ T cell-mediated cytotoxicity could eliminate primary melanoma cells but the efficacy depended on MHC class II expression.

The associations between PD-1, CTLA-4 gene polymorphisms and susceptibility to ankylosing spondylitis: a meta-analysis and systemic review

Previous surveys had evaluated the effects of the PD-1, CTLA-4 gene polymorphisms on susceptibility to ankylosing spondylitis (AS), but the results remained controversial. To briefly examine these consequences, a comprehensive meta-analysis was conducted to estimate the relationships between PD-1 rs11568821, rs2227982, rs2227981, CTLA-4 +49 A/G and -318 C/T polymorphisms and AS risk. The available articles dated to December 2014 were searched in the PUBMED, MEDLINE and EMBASE databases. The data of the genotypes and/or alleles for the PD-1 rs11568821, rs2227982, rs2227981, CTLA-4 +49 A/G and -318 C/T polymorphisms in the AS and control subjects were extracted, and statistical analysis was conducted by STATA 11.2 software. Summary odds ratios (ORs) with their 95 % confidence intervals (95 % CIs) were calculated to determine the strength of associations with fixed-effects or random-effects models. A total of eight published studies were finally involved in this meta-analysis. Meta-analysis of PD-1 rs2227982 polymorphism under the T allele versus C allele (OR 1.744, 95 % CI 1.477-2.059, P < 0.0001), TT+TC versus CC (OR 2.292, 95 % CI 1.654-3.175, P < 0.0001), TT versus CC (OR 1.883, 95 % CI 1.299-2.729, P = 0.001) revealed a significant association with AS. Our meta-analysis demonstrated that the rs2227982 polymorphism in the PD-1 gene might contribute to AS susceptibility. However, further studies with large sample sizes and among different ethnicity populations should be required to confirm this association.

Interaction between HLA-B60 and HLA-B27 as a Better Predictor of Ankylosing Spondylitis in a Taiwanese Population

Objective

Ankylosing spondylitis (AS) is a form of chronic inflammatory spondyloarthritis (SpA) that causes pain and stiffness in spines or joints. Human leukocyte antigen B27 (HLA-B27) and B60 (HLA-B60) have been reported as major genetic risk factors of AS. In addition, rs13202464, located on major histocompatibility complex (MHC) region, showed high sensitivity (98.7%) and specificity (98.0%) for HLA-B27.

Design

The aim of our study is to test whether the interaction between HLA-B60 and HLA-B27 (rs13202464) can serve as a better predictor of AS. We have genotyped HLA-B60 and rs13202464 among 471 patients with AS and 557 healthy subjects. Combined risk factors were investigated to test the biological interaction.

Results

Our results indicated that the relative risk (RR) for HLA-B27+/HLA-B60− was 152 (95% CI 91 to 255) and it increased to 201 (95% CI 85 to 475) in HLA-B27+/HLA-B60+ patients (with HLA-B27−/HLA-B60− as reference). Combinational analysis of two risk factors (HLA-B27+/HLA-B60+) showed a relative excess risk due to interaction (RERI) of 46.79 (95% CI: -117.58 to 211.16), attributable proportion (AP) of 0.23 (95% CI: -0.41 to 0.88) and a synergy index (S) of 1.31 (95% CI: 0.56 to 3.04).

Conclusion

In conclusion, genetic interaction analysis revealed that the interaction between HLA-B60 and HLA-B27 is a better marker for the risk of AS susceptibility in a Taiwanese population.

Characterization and clinical relevance of circulating CD4+CD28- T cells in Graves' disease

During autoimmune disease the fraction of CD4+CD28- T cells in the peripheral blood of has been found to be elevated. In the present study, peripheral blood was collected from 61 patients with Graves' disease (GD) and 30 healthy control participants. Serum concentrations of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and thyrotropin receptor autoantibody (TRAb) were measured and peripheral blood mononuclear cell (PBMC) surface expression of CD4 and CD28 molecules was detected by flow cytometry. CD4+CD28- cells were sorted from six patients undergoing subtotal thyroidectomy and cultured ex vivo. The influence of TSH pretreated thyroid follicular cells on CD4+CD28- cell proliferation was evaluated using the agonist CD40 mAb 5C11, the blocking CD40L mAb 4F1 or B7-1 mAb 4E5 in 3H-TdR assays. Our data showed that the fraction of CD4+CD28- T cells was higher in GD patients than healthy donors (10.21%±8.56% vs. 2.33%±1.94%; P<0.001), and further elevated in 24 of 61 patients with Graves' ophthalmopathy (GO) (7.00±6.57% vs. 15.21±8.96%; P<0.001). A higher proportion of CD4+CD28- cells was detected in patients with degree II or III goiter than those with degree I goiter (11.53±9.18% vs. 6.11±3.97%; P<0.05 and 14.50±10.41% vs. 6.11±3.97%; P<0.01). The percentage of CD4+CD28- T cells correlated positively with serum levels of FT3 (r=0.354, P<0.01) and TRAb (r=0.304, P<0.05), but did not correlate with serum FT4 or TSH. Ex vivo, 5C11 enhanced proliferation of CD4+CD28+ cells (P<0.05), but did not influence the proliferation of CD4+CD28- cells. 4F1 inhibited the proliferation of both CD4+CD28+ (P<0.05) and CD4+CD28- (P<0.01) cells, and 4E5 inhibited proliferation of CD4+CD28+ cells (P<0.05). The elevation in circulating CD4+CD28- cells in GD patients correlates with disease severity and maybe plays an important role in the pathogenesis of GD.

The story of CD4+ CD28- T cells revisited: solved or still ongoing?

CD4⁺CD28⁻ T cells are a unique type of proinflammatory T cells characterised by blockade of costimulatory CD28 receptor expression at the transcriptional level, which is still reversible by IL-12. In healthy individuals older than 65 years, these cells may accumulate to up to 50% of total CD4⁺ T lymphocytes as in many immune-mediated diseases, immunodeficiency, and specific infectious diseases. Here we focus on CD4⁺CD28⁻ T cells in chronic immune-mediated diseases, summarizing various phenotypic and functional characteristics, which vary depending on the underlying disease, disease activity, and concurrent treatment. CD4⁺CD28⁻ T cells present as effector/memory cells with increased replicative history and oligoclonality but reduced apoptosis. As an alternative costimulatory signal instead of CD28, not only natural killer cell receptors and Toll-like receptors, but also CD47, CTLA-4, OX40, and 4-1BB have to be considered. The proinflammatory and cytotoxic capacities of these cells indicate an involvement in progression and maintenance of chronic immune-mediated disease. So far it has been shown that treatment with TNF-α blockers, abatacept, statins, and polyclonal antilymphocyte globulins (ATG) mediates reduction of the CD4⁺CD28⁻ T cell level. The clinical relevance of targeting CD4⁺CD28⁻ T cells as a therapeutic option has not been examined so far.

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.

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.

Alterations in both the activatory and inhibitory potential of peripheral blood CD4+ T cells in rheumatoid arthritis patients correlate with disease progression

The chronic nature of rheumatoid arthritis (RA) suggests immune dysfunction, including persistent systemic activation. Therefore, we evaluated the activatory and inhibitory potential as well as proliferative activity of peripheral blood (PB) CD4+ T cells from RA patients in different stages of the disease and after different therapeutic interventions. We found that CD4+ T cells from RA patients were activated in vivo concerning decreased CD28 expression and increase of CD40L, CD69, and CTLA-4 expression; however, the extent of stimulation was suboptimal when compared to healthy controls. Consequently, impaired proliferative activities of these cells were found in all patients irrespective of the active disease duration. Treatment with methotrexate (MTX) and/or inhibitors of TNF-alpha (iTNF) did not significantly influence systemic activation in RA patients, which corresponded with the maintenance of inflammation markers; however, partial restoration of CD28 and CTLA-4 expression as well as clinical improvement were observed. In patients with early disease (the MTX group), we noted higher capacity of CD4+ T cells for restoration of T cell function, whereas cells from the iTNF group with progressive disease remained with a proliferative defect after the treatment. In conclusion, our study demonstrates that the dysregulated expression of molecules interfering with CD4+ T cell signaling may result in functional impairment of the effector T cells and correlates with disease progression.

Impairment of CD4+ cytotoxic T cells predicts poor survival and high recurrence rates in patients with hepatocellular carcinoma

The role of CD4(+) cytotoxic T cells (CTLs) in hepatocellular carcinoma (HCC) remains obscure. This study characterized CD4(+) CTLs in HCC patients and further elucidated the associations between CD4(+) CTLs and HCC disease progression. In all, 547 HCC patients, 44 chronic hepatitis B (CHB) patients, 86 liver cirrhosis (LC) patients, and 88 healthy individuals were enrolled in the study. CD4(+) CTLs were defined by flow cytometry, immunohistochemistry, and lytic granule exocytosis assays. A multivariate analysis of prognostic factors for overall survival was performed using the Cox proportional hazards model. Circulating and liver-infiltrating CD4(+) CTLs were found to be significantly increased in HCC patients during early stage disease, but decreased in progressive stages of HCC. This loss of CD4(+) CTLs was significantly correlated with high mortality rates and reduced survival time of HCC patients. In addition, the proliferation, degranulation, and production of granzyme A, granzyme B, and perforin of CD4(+) CTLs were inhibited by the increased forkhead/winged helix transcription factor (FoxP3(+) ) regulatory T cells in these HCC patients. Further analysis showed that both circulating and tumor-infiltrating CD4(+) CTLs were independent predictors of disease-free survival and overall survival after the resection of the HCC.

CONCLUSION

The progressive deficit in CD4(+) CTLs induced by increased FoxP3(+) regulatory T cells was correlated with poor survival and high recurrence rates in HCC patients. These data suggest that CD4(+) CTLs may represent both a potential prognostic marker and a therapeutic target for the treatment of HCC.

Senescence marker killer cell lectin-like receptor G1 (KLRG1) contributes to TNF-α production by interaction with its soluble E-cadherin ligand in chronically inflamed joints

OBJECTIVES

Killer cell lectin-like receptor G1 (KLRG1) is an NK cell marker also expressed on T cells showing an immunosenescent phenotype. KLRG1 binding to its ligand E-cadherin inhibits functional responses. It was recently shown that soluble E-cadherin (sE-cadherin) also influences KLRG1 signalling, although its involvement in arthritis is unknown. Our goal was to evaluate the contribution of KLRG1(+) T cells to synovitis.

METHODS

Paired peripheral blood (PB) and synovial fluid (SF) mononuclear cells from 21 patients with spondyloarthritis (SpA) or rheumatoid arthritis (RA), eight with crystal-induced arthritis and 10 controls were obtained. T cells were characterised for KLRG1 expression directly ex vivo, while TNF-α/IFN-γ production was assessed after polyclonal stimulation. Assays of chemotaxis response towards SF were conducted. Additionally, sE-cadherin levels in our paired samples were determined. Moreover, TNF-α/IFN-γ production by antigen-specific T cells was evaluated in the presence of sE-cadherin.

RESULTS

KLRG1(+) T cells were enriched in SF as opposed to PB of SpA and RA patients, which contrasts with results obtained in crystal-induced arthritides. KLRG1(+) T cells were more functionally active as opposed to KLRG1(-) T cells and migrated preferentially towards SpA and RA SF. sE-cadherin levels were higher in SF versus plasma. The presence of sE-cadherin enhanced the number of KLRG1(+) CD4(+) T cells able to produce TNF-α but not IFN-γ.

CONCLUSIONS

sE-cadherin contributes to the local proinflammatory environment in the joint by favouring TNF-α production by KLRG1(+) CD4(+) T cells. This pathway seems to be operational in both SpA and RA, but not in crystal-induced arthritis.

NKG2D stimulated T-cell autoreactivity in giant cell arteritis and polymyalgia rheumatica

OBJECTIVE

To investigate functional expression of NKG2D on CD4 and CD8 T-cells in patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR).

METHODS

Peripheral blood was drawn from patients with GCA (n=16), PMR (n=78) and healthy controls (HC, n=64). Tissue samples were obtained from GCA patients and controls. Proliferation and cytokine production assays were performed using CFSE and intracellular IFN-γ or TNF-α staining, respectively, and flow cytometry analysis. Immunofluorescence and immunohistology were applied to analyse the presence of NKG2D-expressing T-cells and NKG2D-ligands in temporal arteries, respectively. mRNA levels of NKG2D-ligands were determined by RT-PCR.

RESULTS

In both GCA and PMR patients, NKG2D was preferentially expressed on senescent CD4CD28(-) and CD8CD28(-), as well as on CD8CD28 T-cells. Frequencies of senescent T-cells were increased in GCA and PMR patients compared to HC. In GCA tissue samples, infiltrating T-cells were predominately CD28(-). NKG2D expressing T-cells concentrated around the vasa vasorum of the adventitia. Antigenic stimulation induced rapid up-regulation of NKG2D on CD4CD28(-) and CD4CD28 T-cells, whereas TNF-α and interleukin-15 enhanced NKG2D expression on senescent CD4 and CD8 T-cells only. NKG2D cross-linkage augmented anti-CD3 triggered proliferation, IFN-γ and TNF-α production of CD8 T-cells. In CD4CD28(-) T-cells, NKG2D ligation resulted in increased IFN-γ production only. NKG2D ligands were expressed in temporal arteries from GCA patients, particularly in the adventitial and medial layers of affected vessels.

CONCLUSIONS

NKG2D is functionally expressed on CD4CD28(-) and CD8 T-cells in GCA and PMR. NKG2D-ligands are present in temporal arteries and may co-stimulate NKG2D expressing T-cells.

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.

Defining a functionally distinct subset of human memory CD4+ T cells that are CD25POS and FOXP3NEG

Surface expression of the IL-2 receptor α-chain (CD25) has been used to discriminate between CD4(+) CD25(HI) FOXP3(+) regulatory T (Treg) cells and CD4(+) CD25(NEG) FOXP3(-) non-Treg cells. However, this study reports that the majority of resting human memory CD4(+) FOXP3(-) T cells expresses intermediate levels of CD25 and that CD25 expression can be used to delineate a functionally distinct memory subpopulation. The CD25(NEG) memory T-cell population contains the vast majority of late differentiated cells that respond to antigens associated with chronic immune responses and are increased in patients with systemic lupus erythematosus (SLE). In contrast, the CD25(INT) memory T cells respond to antigens associated with recall responses, produce a greater array of cytokines, and are less dependent on costimulation for effector responses due to their expression of CD25. Lastly, compared to the CD25(NEG) and Treg-cell populations, the CD25(INT) memory population is lost to a greater degree from the blood of cancer patients treated with IL-2. Collectively, these results show that in humans, a large proportion of CD4(+) memory T cells express intermediate levels of CD25, and this CD25(INT) FOXP3(-) subset is a functionally distinct memory population that is uniquely affected by IL-2.

Prevalence of circulating CD4+CD28null T cells is associated with early atherosclerotic damage in patients with end-stage renal disease undergoing hemodialysis

CD4(+) T-cell subsets lacking surface CD28 in peripheral blood have been suggested to predispose people to atherosclerosis. To determine if CD4(+)CD28(null) T cells are involved in the immunopathological process of atherosclerotic damage in end-stage renal disease (ESRD) patients undergoing hemodialysis (HD), we characterized peripheral-blood CD4(+)CD28(null) T cells from HD patients and investigated the association between these cells and early atherosclerotic damage. Four color flow cytometric analyses showed that HD patients had significantly higher percentages of CD4(+)CD28(null) T cells in circulating blood than healthy subjects (HS). Most HD patient-derived CD4(+)CD28(null) T cells expressed higher levels of CX3CR1 and produced more intracellular IFN-γ, perforin and granzyme B than their counterparts. Regression analyses demonstrated that the increased levels of CD4(+)CD28(null) T cells were positively correlated to serum levels of C-reactive protein, suggesting systemic inflammation and atherosclerosis. Furthermore, phenotypic and functional studies of CD4(+)CD28(null) T cells showed that these cells were closely correlated with impaired flow-mediated vasodilation and increased intima-media thickness in the carotid artery, which are markers of early atherosclerosis. These data suggested that CD4(+)CD28(null) T cells are important effector cells in HD patients, and that these cells may have a critical role in mediating early atherosclerotic damage.

Apoptotic effects of antilymphocyte globulins on human pro-inflammatory CD4+CD28- T-cells

Background

Pro-inflammatory, cytotoxic CD4⁺CD28⁻ T-cells with known defects in apoptosis have been investigated as markers of premature immuno-senescence in various immune-mediated diseases. In this study we evaluated the influence of polyclonal antilymphocyte globulins (ATG-Fresenius, ATG-F) on CD4⁺CD28⁻ T-cells in vivo and in vitro.

Principal Findings

Surface and intracellular three colour fluorescence activated cell sorting analyses of peripheral blood mononuclear cells from 16 consecutive transplant recipients and short-term cell lines were performed. In vivo, peripheral levels of CD3⁺CD4⁺CD28⁻ T-cells decreased from 3.7±7.1% before to 0±0% six hours after ATG-F application (P = 0.043) in 5 ATG-F treated but not in 11 control patients (2.9±2.9% vs. 3.9±3.0%). In vitro, ATG-F induced apoptosis even in CD4⁺CD28⁻ T-cells, which was 4.3-times higher than in CD4⁺CD28⁺ T-cells. ATG-F evoked apoptosis was partially reversed by the broad-spectrum caspase inhibitor benzyloxycarbonyl (Cbz)-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk) and prednisolon-21-hydrogensuccinate. ATG-F triggered CD25 expression and production of pro-inflammatory cytokines, and induced down-regulation of the type 1 chemokine receptors CXCR-3, CCR-5, CX3CR-1 and the central memory adhesion molecule CD62L predominately in CD4⁺CD28⁻ T-cells.

Conclusion

In summary, in vivo depletion of peripheral CD3⁺CD4⁺CD28⁻ T-cells by ATG-F in transplant recipients was paralleled in vitro by ATG-F induced apoptosis. CD25 expression and chemokine receptor down-regulation in CD4⁺CD28⁻ T-cells only partly explain the underlying mechanism.

NKG2D expression in CD4+ T lymphocytes as a marker of senescence in the aged immune system

Human aging is characterized by changes in the immune system which have a profound impact on the T-cell compartment. These changes are more frequently found in CD8+ T cells, and there are not well-defined markers of differentiation in the CD4+ subset. Typical features of cell immunosenescence are characteristics of pathologies in which the aberrant expression of NKG2D in CD4+ T cells has been described. To evaluate a possible age-related expression of NKG2D in CD4+ T cells, we compared their percentage in peripheral blood from 100 elderly and 50 young adults. The median percentage of CD4+ NKG2D+ in elders was 5.3% (interquartile range (IR): 8.74%) versus 1.4% (IR: 1.7%) in young subjects (p < 0.3 × 10(-10)). CD28 expression distinguished two subsets of CD4+ NKG2D+ cells with distinct functional properties and differentiation status. CD28+ cells showed an immature phenotype associated with high frequencies of CD45RA and CD31. However, most of the NKG2D+ cells belonged to the CD28(null) compartment and shared their phenotypical properties. NKG2D+ cells represented a more advanced stage of maturation and exhibited greater response to CMV (5.3 ± 3.1% versus 3.4 ± 2%, p = 0.037), higher production of IFN-γ (40.56 ± 13.7% versus 24 ± 8.8%, p = 0.015), lower activation threshold and reduced TREC content. Moreover, the frequency of the CD4+ NKG2D+ subset was clearly related to the status of the T cells. Higher frequencies of the NKG2D+ subset were accompanied with a gradual decrease of NAIVE and central memory cells, but also with a higher level of more differentiated subsets of CD4+ T cells. In conclusion, CD4+ NKG2D+ represent a subset of highly differentiated T cells which characterizes the senescence of the immune system.

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.

Impact of age on T cell signaling: a general defect or specific alterations?

Decreased immune responsiveness associated with aging is generally termed "immunosenescence". Several theories have been proposed to explain age-related declines in immune responses. Here, we will focus on and describe potential defects in T cell signal transduction from the membrane to the nucleus, leading to changes in the type, intensity and duration of the response as a major factor contributing to immunosenescence. We will first detail T cell signaling through the T cell receptor (TCR), CD28 and IL-2 receptor (IL-2R) and then discuss the observed age-related alterations to these signaling pathways. The role of membrane rafts in T cell signaling and T cell aging will be described. These factors will be considered in the context of the notion that age-related changes to T cell signaling may be attributed to changes in the functionality of the T cells due to shifts in T cell subpopulations with age. For this reason, we conclude by highlighting the application of multiparametric signaling analysis in leukocyte subsets using flow cytometry as a means to obtain a clearer picture with respect to age-related changes to immune signaling.

[The oligoclonal expansion of T cells: study of its stability over time]

A novel experimental approach to the investigation of the repertoire of peripheral T lymphocytes of patients suffering from ankylosing spondylitis (AS) is proposed. This approach is based on the wide-range sequencing of cDNA of the beta-chain of the T-cellular receptor (TcR). The results of the analysis of the diversity of sequences of the TcR antigen-binding domain (CDR3) inside the total pool of one patient with AS are presented by the example of the second V family (BV2) of TcR. The expansion of six independent TcR-expressing clones of T cells with a similar amino acid sequence of the CDR3 domains was proposed based on the results of the comparative structural analysis of the clone libraries of the cDNA of TcR BV2. The long-time stable expansion of these T clones was demonstrated during the development of the disease by specific monitoring.