Circulating CD4+CD161+ T lymphocytes are increased in seropositive arthralgia patients but decreased in patients with newly diagnosed rheumatoid arthritis

The shared circulating diagnostic biomarkers and molecular mechanisms of systemic lupus erythematosus and inflammatory bowel disease

Background

Systemic lupus erythematosus (SLE) is a multi-organ chronic autoimmune disease. Inflammatory bowel disease (IBD) is a common chronic inflammatory disease of the gastrointestinal tract. Previous studies have shown that SLE and IBD share common pathogenic pathways and genetic susceptibility, but the specific pathogenic mechanisms remain unclear.

Methods

The datasets of SLE and IBD were downloaded from the Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were identified using the Limma package. Weighted gene coexpression network analysis (WGCNA) was used to determine co-expression modules related to SLE and IBD. Pathway enrichment was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for co-driver genes. Using the Least AbsoluteShrinkage and Selection Operator (Lasso) regressionand Support Vector Machine-Recursive Feature Elimination (SVM-RFE), common diagnostic markers for both diseases were further evaluated. Then, we utilizedthe CIBERSORT method to assess the abundance of immune cell infiltration. Finally,we used the single-cell analysis to obtain the location of common diagnostic markers.

Results

71 common driver genes were identified in the SLE and IBD cohorts based on the DEGs and module genes. KEGG and GO enrichment results showed that these genes were closely associated with positive regulation of programmed cell death and inflammatory responses. By using LASSO regression and SVM, five hub genes (KLRF1, GZMK, KLRB1, CD40LG, and IL-7R) were ultimately determined as common diagnostic markers for SLE and IBD. ROC curve analysis also showed good diagnostic performance. The outcomes of immune cell infiltration demonstrated that SLE and IBD shared almost identical immune infiltration patterns. Furthermore, the majority of the hub genes were commonly expressed in NK cells by single-cell analysis.

Conclusion

This study demonstrates that SLE and IBD share common diagnostic markers and pathogenic pathways. In addition, SLE and IBD show similar immune cellinfiltration microenvironments which provides newperspectives for future treatment.

The Airway Microbiome-IL-17 Axis: a Critical Regulator of Chronic Inflammatory Disease

The respiratory tract is home to a diverse microbial community whose influence on local and systemic immune responses is only beginning to be appreciated. Increasing reports have linked changes in this microbiome to a range of pulmonary and extrapulmonary disorders, including asthma, chronic obstructive pulmonary disease and rheumatoid arthritis. Central to many of these findings is the role of IL-17-type immunity as an important driver of inflammation. Despite the crucial role played by IL-17-mediated immune responses in protection against infection, overt Th17 cell responses have been implicated in the pathogenesis of several chronic inflammatory diseases. However, our knowledge of the influence of bacteria that commonly colonise the respiratory tract on IL-17-driven inflammatory responses remains sparse. In this article, we review the current knowledge on the role of specific members of the airway microbiota in the modulation of IL-17-type immunity and discuss how this line of research may support the testing of susceptible individuals and targeting of inflammation at its earliest stages in the hope of preventing the development of chronic disease.

Contribution of pathogenic T helper 1 and 17 cells to bursitis and tenosynovitis in polymyalgia rheumatica

Background

Although polymyalgia rheumatica (PMR) is a very common rheumatic inflammatory disease, current insight into the pathobiology of PMR is limited and largely based on studies in blood. We investigated T helper 1 (T_H1) and T helper 17 (T_H17) cell responses in blood, synovial fluid and bursa tissue of patients with PMR.

Materials and methods

Blood samples were collected from 18 patients with new-onset PMR and 32 healthy controls. Synovial fluid was aspirated from the inflamed shoulder bursae or biceps tendon sheath of 13 patients. Ultrasound-guided biopsies of the subacromial-subdeltoid (SASD) bursa were obtained from 11 patients. T cells were examined by flow cytometry, immunohistochemistry and immunofluorescence staining.

Results

Besides an increase of T_H17 (CD4⁺IL-17⁺IFN-γ^-) cells and T cytotoxic 17 (T_C17; CD8⁺IL-17⁺IFN-γ^-) cells, no other major changes were noted in the circulating T cell compartment of patients with PMR. Absolute numbers of CD4⁺ and CD8⁺ T cells were similar in blood and synovial fluid of patients with PMR. Synovial fluid T cells showed an effector-memory (CD45RO⁺CCR7^-) phenotype. Percentages of T_H1 (CD4⁺IFN-γ⁺IL-17^-) cells and T_H1/T_H17 (CD4⁺IFN-γ⁺IL-17⁺) cells, but not T_H17 or T_C17 cells, were increased in the synovial fluid. Bursa tissue biopsies contained a small number of T cells, which were mostly CD8 negative. The majority of bursa tissue T cells produced IFN-γ but not IL-17. For comparison, B cells were scarcely detected in the bursa tissue.

Conclusion

Although the circulating T_H17 cell pool is expanded in patients with PMR, our findings indicate that T_H1 cells are involved in the inflammation of bursae and tendon sheaths in this condition. Our study points towards the T_H1 cell pathway as a potential target for therapy in PMR.

EULAR points to consider for conducting clinical trials and observational studies in individuals at risk of rheumatoid arthritis

BACKGROUND

Despite growing interest, there is no guidance or consensus on how to conduct clinical trials and observational studies in populations at risk of rheumatoid arthritis (RA).

METHODS

An European League Against Rheumatism (EULAR) task force formulated four research questions to be addressed by systematic literature review (SLR). The SLR results informed consensus statements. One overarching principle, 10 points to consider (PTC) and a research agenda were proposed. Task force members rated their level of agreement (1-10) for each PTC.

RESULTS

Epidemiological and demographic characteristics should be measured in all clinical trials and studies in at-risk individuals. Different at-risk populations, identified according to clinical presentation, were defined: asymptomatic, musculoskeletal symptoms without arthritis and early clinical arthritis. Study end-points should include the development of subclinical inflammation on imaging, clinical arthritis, RA and subsequent achievement of arthritis remission. Risk factors should be assessed at baseline and re-evaluated where appropriate; they include genetic markers and autoantibody profiling and additionally clinical symptoms and subclinical inflammation on imaging in those with symptoms and/or clinical arthritis. Trials should address the effect of the intervention on risk factors, as well as progression to clinical arthritis or RA. In patients with early clinical arthritis, pharmacological intervention has the potential to prevent RA development. Participants' knowledge of their RA risk may inform their decision to participate; information should be provided using an individually tailored approach.

CONCLUSION

These consensus statements provide data-driven guidance for rheumatologists, health professionals and investigators conducting clinical trials and observational studies in individuals at risk of RA.

Application of Weighted Gene Coexpression Network Analysis to Identify Key Modules and Hub Genes in Systemic Juvenile Idiopathic Arthritis

Systemic juvenile idiopathic arthritis (sJIA) is a severe autoinflammatory disorder with a still not clearly defined molecular mechanism. To better understand the disease, we used scattered datasets from public domains and performed a weighted gene coexpression network analysis (WGCNA) to identify key modules and hub genes underlying sJIA pathogenesis. Two gene expression datasets, GSE7753 and GSE13501, were used to construct the WGCNA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were applied to the genes and hub genes in the sJIA modules. Cytoscape was used to screen and visualize the hub genes. We further compared the hub genes with the genome-wide association study (GWAS) genes and used a consensus WGCNA to verify that our conclusions were conservative and reproducible across multiple independent datasets. A total of 5,414 genes were obtained for WGCNA, from which highly correlated genes were divided into 17 modules. The red module demonstrated the highest correlation with the sJIA module (r = 0.8, p = 3e⁻²⁹), whereas the green-yellow module was found to be closely related to the non-sJIA module (r = 0.62, p = 1e⁻¹⁴). Functional enrichment analysis demonstrated that the red module was mostly enriched in the activation of immune responses, infection, nucleosomes, and erythrocytes, and the green-yellow module was mostly enriched in immune responses and inflammation. Additionally, the hub genes in the red module were highly enriched in erythrocyte differentiation, including ALAS2, AHSP, TRIM10, TRIM58, and KLF1. The hub genes from the green-yellow module were mainly associated with immune responses, as exemplified by the genes KLRB1, KLRF1, CD160, and KIRs. We identified sJIA-related modules and several hub genes that might be associated with the development of sJIA. Particularly, the modules may help understand the mechanisms of sJIA, and the hub genes may become biomarkers and therapeutic targets of sJIA in the future.

Rheumatoid arthritis CD14+ monocytes display metabolic and inflammatory dysfunction, a phenotype that precedes clinical manifestation of disease

Introduction

This study investigates the metabolic activity of circulating monocytes and their impact on pro‐inflammatory responses in RA and explores whether this phenotype is already primed for inflammation before clinical manifestations of disease.

Methods

Blood was collected and CD14⁺ monocytes isolated from healthy control donors (HC), individuals at‐risk (IAR) and RA patients. Monocyte frequency in blood and synovial tissue was assessed by flow cytometry. Inflammatory responses and metabolic analysis ± specific inhibitors were quantified by RT‐PCR, Western blot, migration assays, Seahorse‐XFe‐technology, mitotracker assays and transmission electron microscopy. Transcriptomic analysis was performed on HC, IAR and RA synovial tissue.

Results

CD14⁺ monocytes from RA patients are hyper‐inflammatory following stimulation, with significantly higher expression of cytokines/chemokines than those from HC. LPS‐induced RA monocyte migratory capacity is consistent with increased monocyte frequency in RA synovial tissue. RA CD14⁺ monocytes show enhanced mitochondrial respiration, biogenesis and alterations in mitochondrial morphology. Furthermore, RA monocytes display increased levels of key glycolytic enzymes HIF1α, HK2 and PFKFB3 and demonstrate a reliance on glucose consumption, blockade of which abrogates pro‐inflammatory mediator responses. Blockade of STAT3 activation inhibits this forced glycolytic flux resulting in metabolic reprogramming and resolution of inflammation. Interestingly, this highly activated monocytic phenotype is evident in IAR of developing disease, in addition to an enhanced monocyte gene signature observed in synovial tissue from IAR.

Conclusion

RA CD14⁺ monocytes are metabolically re‐programmed for sustained induction of pro‐inflammatory responses, with STAT3 identified as a molecular regulator of metabolic dysfunction. This phenotype precedes clinical disease onset and may represent a potential pathway for therapeutic targeting early in disease.

Quantifying circulating Th17 cells by qPCR: potential as diagnostic biomarker for rheumatoid arthritis

OBJECTIVE

The diagnosis of RA patients remains a challenge, especially in ACPA-negative disease. Novel T-cell subsets, particularly Th17 may be useful, although data on Th17 frequency using flow cytometry in RA are conflicting. We investigated whether a novel epigenetic qPCR assay for the quantification of Th17 could differentiate patients with RA from those with symptoms evolving towards an alternative diagnosis.

METHODS

We used a qPCR assay measuring the extent of the methylation at a key position in the IL-17 and CD4 genes. Assays were performed on whole blood from 49 healthy controls (HC) and 165 early arthritis clinic patients. Flow cytometry was further used to detect the expression of CXCR4 on Th17 cells.

RESULTS

In 75 inflammatory arthritis patients who progressed to RA, the qPCR assays showed significantly fewer Th17 cells compared with 90 patients who did not (P<0.0001). Regression models demonstrated a high predictive value for RA development (75.8% correct prediction), and particularly for the ACPA-negative group (n = 125) where Th17 and swollen joint count (SJC) were the only predictors (73% correct prediction). The chemokine receptor CXCR4 had significantly higher expression on Th17 from early RA patients (n = 11) compared with HC (n = 15).

CONCLUSION

The results of the epigenetic qPCR assay showed that low levels of Th17 cells were predictive of developing RA, particularly in the ACPA-negative patients. This could have value for insights into pathogenesis and management. The results suggest the recruitment of Th17 to the inflammatory disease site, consistent with high CXCR4 expression.

Mucosa-Environment Interactions in the Pathogenesis of Rheumatoid Arthritis

Mucosal surfaces play a central role in the pathogenesis of rheumatoid arthritis (RA). Several risk factors, such as cigarette smoking, environmental pollution, and periodontitis interact with the host at the mucosal level, triggering immune system activation. Moreover, the alteration of microbiota homeostasis is gaining increased attention for its involvement in the disease pathogenesis, modulating the immune cell response at a local and subsequently at a systemic level. Currently, the onset of the clinical manifest arthritis is thought to be the last step of a series of pathogenic events lasting years. The positivity for anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF), in absence of symptoms, characterizes a preclinical phase of RA-namely systemic autoimmune phase- which is at high risk for disease progression. Several immune abnormalities, such as local ACPA production, increased T cell polarization towards a pro-inflammatory phenotype, and innate immune cell activation can be documented in at-risk subjects. Many of these abnormalities are direct consequences of the interaction between the environment and the host, which takes place at the mucosal level. The purpose of this review is to describe the humoral and cellular immune abnormalities detected in subjects at risk of RA, highlighting their origin from the mucosa-environment interaction.

Assessing prognosis and prediction of treatment response in early rheumatoid arthritis: systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, debilitating disease associated with reduced quality of life and substantial costs. It is unclear which tests and assessment tools allow the best assessment of prognosis in people with early RA and whether or not variables predict the response of patients to different drug treatments.

OBJECTIVE

To systematically review evidence on the use of selected tests and assessment tools in patients with early RA (1) in the evaluation of a prognosis (review 1) and (2) as predictive markers of treatment response (review 2).

DATA SOURCES

Electronic databases (e.g. MEDLINE, EMBASE, The Cochrane Library, Web of Science Conference Proceedings; searched to September 2016), registers, key websites, hand-searching of reference lists of included studies and key systematic reviews and contact with experts.

STUDY SELECTION

Review 1 - primary studies on the development, external validation and impact of clinical prediction models for selected outcomes in adult early RA patients. Review 2 - primary studies on the interaction between selected baseline covariates and treatment (conventional and biological disease-modifying antirheumatic drugs) on salient outcomes in adult early RA patients.

RESULTS

Review 1 - 22 model development studies and one combined model development/external validation study reporting 39 clinical prediction models were included. Five external validation studies evaluating eight clinical prediction models for radiographic joint damage were also included. c-statistics from internal validation ranged from 0.63 to 0.87 for radiographic progression (different definitions, six studies) and 0.78 to 0.82 for the Health Assessment Questionnaire (HAQ). Predictive performance in external validations varied considerably. Three models [(1) Active controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset (ASPIRE) C-reactive protein (ASPIRE CRP), (2) ASPIRE erythrocyte sedimentation rate (ASPIRE ESR) and (3) Behandelings Strategie (BeSt)] were externally validated using the same outcome definition in more than one population. Results of the random-effects meta-analysis suggested substantial uncertainty in the expected predictive performance of models in a new sample of patients. Review 2 - 12 studies were identified. Covariates examined included anti-citrullinated protein/peptide anti-body (ACPA) status, smoking status, erosions, rheumatoid factor status, C-reactive protein level, erythrocyte sedimentation rate, swollen joint count (SJC), body mass index and vascularity of synovium on power Doppler ultrasound (PDUS). Outcomes examined included erosions/radiographic progression, disease activity, physical function and Disease Activity Score-28 remission. There was statistical evidence to suggest that ACPA status, SJC and PDUS status at baseline may be treatment effect modifiers, but not necessarily that they are prognostic of response for all treatments. Most of the results were subject to considerable uncertainty and were not statistically significant.

LIMITATIONS

The meta-analysis in review 1 was limited by the availability of only a small number of external validation studies. Studies rarely investigated the interaction between predictors and treatment.

SUGGESTED RESEARCH PRIORITIES

Collaborative research (including the use of individual participant data) is needed to further develop and externally validate the clinical prediction models. The clinical prediction models should be validated with respect to individual treatments. Future assessments of treatment by covariate interactions should follow good statistical practice.

CONCLUSIONS

Review 1 - uncertainty remains over the optimal prediction model(s) for use in clinical practice. Review 2 - in general, there was insufficient evidence that the effect of treatment depended on baseline characteristics.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016042402.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Sex-based differences in association between circulating T cell subsets and disease activity in untreated early rheumatoid arthritis patients

BACKGROUND

It is not known if sex-based disparities in immunological factors contribute to the disease process in rheumatoid arthritis (RA). Hence, we examined whether circulating T cell subset proportions and their association with disease activity differed in male and female patients with untreated early rheumatoid arthritis (ueRA).

METHODS

Proportions of T cell subsets were analyzed in peripheral blood from 72 ueRA DMARD- and corticosteroid-naïve patients (50 females and 22 males) and in 31 healthy age- and sex-matched controls. Broad analysis of helper and regulatory CD4⁺ T cell subsets was done using flow cytometry. Disease activity in patients was assessed using DAS28, CDAI, swollen joint counts, tender joint counts, CRP, and ESR.

RESULTS

Multivariate factor analyses showed that male and female ueRA patients display distinct profiles of association between disease activity and circulating T cell subset proportions. In male, but not female, ueRA patients Th2 cells showed a positive association with disease activity and correlated significantly with DAS28-ESR, CDAI, and swollen and tender joint counts. Likewise, proportions of non-regulatory CTLA-4⁺ T cells associated positively with disease activity in male patients only, and correlated with DAS28-ESR. In contrast, there was a negative relation between Th1Th17 subset proportions and disease activity in males only. The proportions of Th17 cells correlated positively with DAS28-ESR in males only, while proportions of Th1 cells showed no relation to disease activity in either sex. There were no significant differences in proportions of T cell subsets between the sexes in patients with ueRA.

CONCLUSIONS

Our findings show sex-based differences in the association between T cell subsets and disease activity in ueRA patients, and that Th2 helper T cells may have a role in regulating disease activity in male patients.

Impact of Aging on the Frequency, Phenotype, and Function of CD161-Expressing T Cells

Immune-aging is associated with perturbed immune responses in the elderly. CD161-expressing T cells, i.e., the previously described subsets of CD161⁺ CD4⁺ T cells, CD161^high CD8⁺ T cells, and CD161^int CD8⁺ T cells, are highly functional, pro-inflammatory T cells. These CD161-expressing T cells are critical in immunity against microbes, while possibly contributing to autoimmune diseases. So far, little is known about the impact of aging on the frequency, phenotype, and function of these CD161-expressing T cells. In the current study, we investigated the impact of aging on CD161⁺ CD4⁺ T cells, CD161^high CD8⁺ T cells, and CD161^int CD8⁺ T cells in peripheral blood samples of 96 healthy subjects (age 20–84). Frequencies of CD161⁺ CD4⁺ T cells and CD161^int CD8⁺ T cells were stable with aging, whereas frequencies of CD161^high CD8⁺ T cells declined. Although CD161^high CD8⁺ T cells were mostly T cell receptor-Vα7.2⁺ mucosal-associated invariant T cells, CD161 expressing CD4⁺ and CD8⁺ T cells showed a limited expression of markers for gamma–delta T cells or invariant natural killer (NK) T cells, in both young and old subjects. In essence, CD161-expressing T cells showed a similar memory phenotype in young and old subjects. The expression of the inhibitory NK receptor KLRG1 was decreased on CD161⁺ CD4⁺ T cells of old subjects, whereas the expression of other NK receptors by CD161-expressing T cells was unaltered with age. The expression of cytotoxic effector molecules was similar in CD161^high and CD161^int CD8⁺ T cells of young and old subjects. The ability to produce pro-inflammatory cytokines was preserved in CD161^high and CD161^int CD8⁺ T cells of old subjects. However, the percentages of IFN-γ⁺ and interleukin-17⁺ cells were significantly lower in CD161⁺ CD4⁺ T cells of old individuals than those of young individuals. In addition, aging was associated with a decrease of nonclassic T helper 1 cells, as indicated by decreased percentages of CD161-expressing cells within the IFN-γ⁺ CD4⁺ T cell compartment of old subjects. Taken together, aging is associated with a numerical decline of circulating CD161^high CD8⁺ T cells, as well as a decreased production of pro-inflammatory cytokines by CD161⁺ CD4⁺ T cells. These aging-associated changes could contribute to perturbed immunity in the elderly.

From patients with arthralgia, pre-RA and recently diagnosed RA: what is the current status of understanding RA pathogenesis?

It is believed that therapy for rheumatoid arthritis (RA) is the most effective and beneficial within a short time frame around RA diagnosis. This insight has caused a shift from research in patients with established RA to patients at risk of developing RA and recently diagnosed patients. It is important for improvement of RA therapy to understand when and what changes occur in patients developing RA. This is true for both seropositive and seronegative patients. Activation of the immune system as presented by autoantibodies, increased cytokine and chemokine production, and alterations within several immune cells occur during RA development. In this review we describe RA pathogenesis with a focus on knowledge obtained from patients with arthralgia, pre-RA and recently diagnosed RA. Connections are proposed between altered immune cells, cytokines and chemokines, and events like synovial hyperplasia, pain and bone damage.

Alteration of the intestinal microbiome characterizes preclinical inflammatory arthritis in mice and its modulation attenuates established arthritis

Perturbations of the intestinal microbiome have been observed in patients with new-onset and chronic autoimmune inflammatory arthritis. However, it is currently unknown whether these alterations precede the development of arthritis or are rather a consequence of disease. Modulation of intestinal microbiota by oral antibiotics or germ-free condition can prevent arthritis in mice. Yet, the therapeutic potential of modulation of the microbiota after the onset of arthritis is not well characterized. We here show that the intestinal microbial community undergoes marked changes in the preclinical phase of collagen induced arthritis (CIA). The abundance of the phylum Bacteroidetes, specifically families S24-7 and Bacteroidaceae was reduced, whereas Firmicutes and Proteobacteria, such as Ruminococcaceae, Lachnospiraceae and Desulfovibrinocaceae, were expanded during the immune-priming phase of arthritis. In addition, we found that the abundance of lamina propria Th17, but not Th1, cells is highly correlated with the severity of arthritis. Elimination of the intestinal microbiota during established arthritis specifically reduced intestinal Th17 cells and attenuated arthritis. These effects were associated with reduced serum amyloid A expression in ileum and synovial tissue. Our observations suggest that intestinal microbiota perturbations precede arthritis, and that modulation of the intestinal microbiota after the onset of arthritis may offer therapeutic opportunities.

Preventing progression from arthralgia to arthritis: targeting the right patients

Early treatment is associated with improved outcomes in patients with rheumatoid arthritis (RA), suggesting that a 'window of opportunity', in which the disease is most susceptible to disease-modifying treatment, exists. Autoantibodies and markers of systemic inflammation can be present long before clinical arthritis, and maturation of the immune response seems to coincide with the development of RA. The pre-arthritis phase associated with symptoms such as as joint pain without clinical arthritis (athralgia) is now hypothesized to fall within the aforementioned window of opportunity. Consequently, disease modulation in this phase might prevent the occurrence of clinically apparent arthritis, which would result in a persistent disease course if untreated. Several ongoing proof-of-concept trials are now testing this hypothesis. This Review highlights the importance of adequate risk prediction for the correct design, execution and interpretation of results of these prevention trials, as well as considerations when translating these findings into clinical practice. The patients' perspectives are discussed, and the accuracy with which RA development can be predicted in patients presenting with arthralgia is evaluated. Currently, the best starting position for preventive studies is proposed to be the inclusion of patients with an increased risk of RA, such as those identified as fulfilling the EULAR definition of 'arthralgia suspicious for progression to RA'.

CD161 identifies polyfunctional Th1/Th17 cells in the genital mucosa that are depleted in HIV-infected female sex workers from Nairobi, Kenya

CD161 identifies a subset of circulating Th17 cells that are depleted in the blood and gut of HIV-infected individuals. In the female reproductive tract (FRT), the pattern of CD161 expression on CD4⁺ cells remains unknown. Here, we characterized CD161 expression in the FRT of Kenyan female sex workers (FSW). Compared to the blood, CD161⁺CD4⁺ T cells were enriched in the FRT of uninfected FSWs. These cells were depleted in FRT of HIV-infected FSWs. Cervical CD161⁺ cells harboured an activated phenotype (CD69, CD95, HLA-DR) with elevated expression of tissue-homing markers (CCR6, β7 integrin) and HIV co-receptor (CCR5). Mitogen-stimulated production of IL-17 confirmed the Th17 commitment of CD161⁺CD4⁺ T cells in the FRT with a predominance of polyfunctional Th1/Th17 cells. Here, we showed that the expression of CD161 on CD4+T cells is modulated at the FRT, but still identified a highly activated cellular subset, which differentiates into pro-inflammatory Th1/Th17 cells, expresses multiple HIV susceptibility markers and are depleted in HIV-infected individuals. The use of CD161 as a biomarker of HIV targets in the FRT reduces the need for functional assessment of cells and could have important implications in better understanding HIV pathogenesis and Th17 fate in the FRT of high-risk women.

The Plasticity of Th17 Cells in the Pathogenesis of Rheumatoid Arthritis

Helper T (Th) cells play an important role in the pathogenesis of autoimmune diseases, including rheumatoid arthritis (RA). It has been revealed that Th17 cells can shift to Th1 cells (i.e., “nonclassic Th1 cells”), which are reported to be more pathogenic than Th17 cells per se. Thus, the association of Th cells in the pathogenesis of autoimmune disease has become more complicated. We recently reported using peripheral blood from untreated and early-onset RA patients that the ratio of CD161+Th1 cells (i.e., Th17-derived Th1 cells to CD161+Th17 cells) is elevated and that levels of interferon-γ (IFNγ)+Th17 cells are inversely correlated with levels of anti-CCP antibodies. Here, we review the plasticity of Th17 cells in the pathogenesis of RA, suggesting possible implications for novel therapies.

Differential Effect of Cytomegalovirus Infection with Age on the Expression of CD57, CD300a, and CD161 on T-Cell Subpopulations

Immunosenescence is a progressive deterioration of the immune system with aging. It affects both innate and adaptive immunity limiting the response to pathogens and to vaccines. As chronic cytomegalovirus (CMV) infection is probably one of the major driving forces of immunosenescence, and its persistent infection results in functional and phenotypic changes to the T-cell repertoire, the aim of this study was to analyze the effect of CMV-seropositivity and aging on the expression of CD300a and CD161 inhibitory receptors, along with the expression of CD57 marker on CD4⁺, CD8⁺, CD8⁺CD56⁺ (NKT-Like) and CD4⁻CD8⁻ (DN) T-cell subsets. Our results showed that, regardless of the T-cell subset, CD57⁻CD161⁻CD300a⁺ T-cells expand with age in CMV-seropositive individuals, whereas CD57⁻CD161⁺CD300a⁺ T-cells decrease. Similarly, CD57⁺CD161⁻CD300a⁺ T-cells expand with age in CMV-seropositive individuals in all subsets except in DN cells and CD57⁻CD161⁺CD300a⁻ T-cells decrease in all T-cell subsets except in CD4⁺ T-cells. Besides, in young individuals, CMV latent infection associates with the expansion of CD57⁺CD161⁻CD300a⁺CD4⁺, CD57⁻CD161⁻CD300a⁺CD4⁺, CD57⁺CD161⁻CD300a⁺CD8⁺, CD57⁻CD161⁻CD300a⁺CD8⁺, CD57⁺CD161⁻CD300a⁺NKT-like, and CD57⁺CD161⁻CD300a⁺DN T-cells. Moreover, in young individuals, CD161 expression on T-cells is not affected by CMV infection. Changes of CD161 expression were only associated with age in the context of CMV latent infection. Besides, CD300a⁺CD57⁺CD161⁺ and CD300a⁻CD57⁺CD161⁺ phenotypes were not found in any of the T-cell subsets studied except in the DN subpopulation, indicating that in the majority of T-cells, CD161 and CD57 do not co-express. Thus, our results show that CMV latent infection impact on the immune system depends on the age of the individual, highlighting the importance of including CMV serology in any study regarding immunosenescence.

Changes in peripheral blood lymphocyte subsets during arthritis development in arthralgia patients

BACKGROUND

Multiple lymphocyte subsets like T and B cells have been connected to joint infiltration and inflammation in rheumatoid arthritis (RA). Identification of leucocyte subsets that are dysregulated in arthritis development could provide insight into the aetiology of RA. This study aimed to investigate the composition of the peripheral blood components, i.e. CD14(+) monocytes, CD4(+) and CD8(+) T lymphocytes (CD3(+)), CD80(+), C-X-C chemokine receptor 3 (CXCR3)(+) and CD27(+) B lymphocytes (CD19(+)), CD16(+)CD56(+)CD3(-) natural killer (NK) cells and activated CD56(+)CD3(+) T cells, for association with arthritis development in patients with arthralgia.

METHODS

Peripheral blood was collected from 89 patients with early RA (disease duration <6 months), 37 healthy controls (HC) and 113 patients with arthralgia (22 developed arthritis within ≤1 year, 18 developed arthritis after >1 year and 73 did not develop arthritis). Absolute numbers of monocytes and lymphocyte subsets in whole heparinized blood were determined with flow cytometry using quantification beads in combination with fluorescent labelled antibodies for T cells, B cells, monocytes, NK cells and activated T cells.

RESULTS

In patients with early RA, significant decreases in numbers of (activated) T cells, CD80(+) and memory B cells and a trend towards smaller numbers of CD8(+) T cells was observed compared to HC. Similar differences were seen in patients with arthralgia who developed or did not develop arthritis (non-converters), with significantly decreased CD8(+) T cells and memory B cells. Patients with arthralgia who developed arthritis were split into groups that developed arthritis within 1 year (early converters) or after 1 year (late converters). Late converters had a significantly decreased number of CD8(+) T cells compared to non-converters; early converters had a decreased number of memory B cells. Longitudinal analysis of converters showed a significant relative increase in CD80(+) B cells towards the conversion time point compared to 24 months prior to conversion.

CONCLUSIONS

This study revealed that patients with arthralgia who develop arthritis demonstrate a change in cellular immune parameters apparent in the periphery, starting with a decrease in cytotoxic T cells 24 months prior to arthritis development, followed by a decrease in the number of memory B cells 12 months prior to disease onset.

Regulatory CD4+ T-Cell Subsets and Anti-Citrullinated Protein Antibody Repertoire: Potential Biomarkers for Arthritis Development in Seropositive Arthralgia Patients?

Objective

Seropositive arthralgia patients (SAP) are at high risk of developing rheumatoid arthritis (RA). This prospective study aimed to determine whether altered peripheral regulatory T-cells (Tregs) and defined subsets, besides a broadened anti-citrullinated protein antibody (ACPA) response, may qualify as biomarkers for RA development in SAP.

Methods

Thirty-four consecutive SAP were prospectively assessed every 6 months for minimally 2 years. At inclusion, peripheral Treg (CD4⁺CD25⁺FoxP3⁺) numbers and subsets, defined as CD45RA⁺FoxP3^low naive Tregs (Fr I), CD45RA^-FoxP3^high activated Tregs (Fr II) and CD45RA^-FoxP3^low non-Tregs (Fr III), were compared to age- and sex-matched healthy controls (HC, n = 16) and treatment-naive RA patients (n = 12). SAP that developed RA were compared to non-switchers and analyzed for Treg numbers and Treg subsets at inclusion. Also, Treg numbers and subsets were compared in switched SAP before and at diagnosis. To assess the ACPA repertoire, IgG and IgA reactivity was measured against citrullinated peptides from fibrinogen, α-enolase and vimentin.

Results

Treg numbers were similar between HC, SAP and RA patients. Although the bonafide Treg subsets Fr I and Fr II were comparable between groups, Fr III was increased in SAP compared to HC (p = 0.01). Fourteen (41%) SAP developed RA during follow-up. Their Treg numbers and subsets were comparable to non-switched SAP. At RA diagnosis, Treg numbers in switched SAP were similar to 6 months before. Switched SAP displayed a more diverse IgG ACPA repertoire compared to non-switched SAP (p = 0.046) and showed more IgA reactivity than non-switched SAP reaching significance for Fib1 only (p = 0.047).

Conclusion

Numbers of Total Treg and bonafide Treg subsets are not indicative for RA development in SAP, opposed to the ACPA repertoire.

Ratio of Circulating IFNγ (+) "Th17 Cells" in Memory Th Cells Is Inversely Correlated with the Titer of Anti-CCP Antibodies in Early-Onset Rheumatoid Arthritis Patients Based on Flow Cytometry Methods of the Human Immunology Project

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic joint inflammation characterized by activated T cells. IL-17 and Th17 cells play important roles in the pathogenesis of RA. Recently, plasticity in helper T cells has been demonstrated; Th17 cells can convert to Th1 cells. However, it remains to be elucidated whether this conversion occurs in the early phase of RA. Here, we validated the methods of the Human Immunology Project using only the cell-surface marker through measuring the actual expression of IL-17 and IFNγ. We also evaluated the expression of CD161 in human Th17 cells. We then tried to identify Th17 cells, IL-17⁺Th17 cells, and IFNγ⁺Th17 cells in the peripheral blood of early-onset RA patients using the standardized method of the Human Immunology Project. Our findings validated the method and the expression of CD161. The ratio of IFNγ⁺Th17 cells in memory T cells was inversely correlated to the titers of anti-CCP antibodies in the early-onset RA patients. These findings suggest that Th17 cells play important roles in the early phase of RA and that anti-IL-17 antibodies should be administered to patients with early phase RA, especially those with high titers of CCP antibodies.

Role of alteration in Treg/Th17 cells' balance in nephropathic patients with Type 2 diabetes mellitus

Introduction

In type 2 diabetes mellitus, the adaptive immune system drives systemic inflammation, promoting insulin resistance and related complications, such as diabetic nephropathy. Increased infiltration of activated T lymphocytes has been found in patients with diabetic nephropathy. T-cell influx and accumulation are the factors that aggravate diabetic nephropathy and link with glomerular filtration surface and albumin excretion. An appropriate balance between pro-inflammatory (T helper 17: Th17, and T helper 1: Th1) and anti-inflammatory (regulatory T cells: Tregs) subsets of T cells is critical to maintain homeostasis and avoid inflammatory disease. The aim of this study was to determine the balance between T helper 17 and regulatory T cells in type 2 diabetic patients who have diabetic nephropathy.

Methods

This case control study was conducted between December 2013 and June 2014 in Theodor Bilharz Research Institute in Egypt. Forty patients and 20 healthy volunteers were recruited in the study, and three groups were formed, i.e. two groups of cases with 20 patients in each group and one group of 20 controls) The groups were 1) 20 type 2 diabetic patients with nephropathy (group A); 2) 20 type 2 diabetic patients without nephropathy (group B); and 3) 20 healthy individuals (control group). Evaluation of T cells was done by standard 2-color flow cytometry.

Results

The study found higher mean of Th17 counts and Th17/Treg ratio among type 2 diabetic nephropathy patients compared to other groups; but a lower mean of Treg count was identified among type 2 diabetic nephropathy patients than in the other groups (p-value = 0.001).

Conclusion

The important role for regulatory T cells in the protection against nephropathy in type 2 diabetic patients was demonstrated, and also it was observed that T helper 17 cells were associated with renal affection.

T cell subsets: an immunological biomarker to predict progression to clinical arthritis in ACPA-positive individuals

Objectives

Anticitrullinated protein antibody (ACPA)+ individuals with non-specific musculoskeletal symptoms are at risk of inflammatory arthritis (IA). This study aims to demonstrate the predictive value of T cell subset quantification for progression towards IA and compare it with previously identified clinical predictors of progression.

Methods

103 ACPA+ individuals without clinical synovitis were observed 3-monthly for 12 months and then as clinically indicated. The end point was the development of IA. Naïve, regulatory T cells (Treg) and inflammation related cells (IRCs) were quantified by flow cytometry. Areas under the ROC curve (AUC) were calculated. Adjusted logistic regressions and Cox proportional hazards models for time to progression to IA were constructed.

Results

Compared with healthy controls (age adjusted where appropriate), ACPA+ individuals demonstrated reduced naïve (22.1% of subjects) and Treg (35.8%) frequencies and elevated IRC (29.5%). Of the 103 subjects, 48(46.6%) progressed. Individually, T cell subsets were weakly predictive (AUC between 0.63 and 0.66), although the presence of 2 T cell abnormalities had high specificity. Three models were compared: model-1 used T cell subsets only, model-2 used previously published clinical parameters, model-3 combined clinical data and T cell data. Model-3 performed the best (AUC 0.79 (95% CI 0.70 to 0.89)) compared with model-1 (0.75 (0.65 to 0.86)) and particularly with model-2 (0.62 (0.54 to 0.76)) demonstrating the added value of T cell subsets. Time to progression differed significantly between high-risk, moderate-risk and low-risk groups from model-3 (p=0.001, median 15.4 months, 25.8 months and 63.4 months, respectively).

Conclusions

T cell subset dysregulation in ACPA+ individuals predates the onset of IA, predicts the risk and faster progression to IA, with added value over previously published clinical predictors of progression.

Expression of Lectin-Like Transcript 1, the Ligand for CD161, in Rheumatoid Arthritis

Objectives

Precursor Th17 lineage cells expressing CD161 are implicated in Rheumatoid Arthritis (RA) pathogenesis. CD4+CD161+ T-cells accumulate in RA joints and may acquire a non classical Th1 phenotype. The endogenous ligand for CD161 is lectin-like transcript 1 (LLT1). CD161/LLT1 ligation may co-stimulate T-cell IFN-γ production. We investigated the presence and identity of LLT1-expressing cells in RA synovial fluid (SF) and synovial tissue (ST). We also assessed levels of soluble LLT1 (sLLT1) in different phases of RA development.

Methods

Paired samples of peripheral blood mononuclear cells (MC) and SFMC (n = 14), digested ST cells (n = 4) and ST paraffin sections (n = 6) from late-stage RA were analyzed for LLT1 expression by flow cytometry and immunohistochemistry. sLLT1 was measured using a sandwich ELISA. Sera and SF from late-stage RA (n = 26), recently diagnosed RA patients (n = 39), seropositive arthralgia patients (SAP, n = 31), spondyloarthropathy patients (SpA, n = 26) and healthy controls (HC, n = 31) were assayed.

Results

In RA SF, LLT1 was expressed by a small proportion of monocytes. In RA ST, LLT1-expressing cells were detected in the lining, sublining layer and in areas with infiltrates. The LLT1 staining pattern overlapped with the CD68 staining pattern. FACS analysis of digested ST confirmed LLT1 expression by CD68+ cells. Elevated systemic sLLT1 was found in all patient groups.

Conclusions

In RA joints, LLT1 is expressed by cells of the monocyte/macrophage lineage. Serum levels of sLLT1 were increased in all patient groups (patients with early- and late-stage RA, seropositive arthralgia and spondyloarthropathy) when compared to healthy subjects.

Polyfunctional, Pathogenic CD161+ Th17 Lineage Cells Are Resistant to Regulatory T Cell-Mediated Suppression in the Context of Autoimmunity

In autoimmune diseases such as rheumatoid arthritis (RA), regulatory T cells (Tregs) fail to constrain autoimmune inflammation; however, the reasons for this are unclear. We investigated T cell regulation in the RA joint. Tregs from RA synovial fluid suppressed autologous responder T cells; however, when compared with Tregs from healthy control peripheral blood, they were significantly less suppressive. Despite their reduced suppressive activity, Tregs in the RA joint were highly proliferative and expressed FOXP3, CD39, and CTLA-4, which are markers of functional Tregs. This suggested that the reduced suppression is due to resistance of RA synovial fluid responder T cells to Treg inhibition. CD161(+) Th17 lineage cells were significantly enriched in the RA joint; we therefore investigated their relative susceptibility to Treg-mediated suppression. Peripheral blood CD161(+) Th cells from healthy controls were significantly more resistant to Treg-mediated suppression, when compared with CD161(-) Th cells, and this was mediated through a STAT3-dependant mechanism. Furthermore, depletion of CD161(+) Th cells from the responder T cell population in RA synovial fluid restored Treg-mediated suppression. In addition, CD161(+) Th cells exhibited pathogenic features, including polyfunctional proinflammatory cytokine production, an ability to activate synovial fibroblasts, and to survive and persist in the inflamed and hypoxic joint. Because CD161(+) Th cells are known to be enriched at sites of autoinflammation, our finding that they are highly proinflammatory and resistant to Treg-mediated suppression suggests an important pathogenic role in RA and other autoimmune diseases.

Percentages of CD4+CD161+ and CD4-CD8-CD161+ T cells in the synovial fluid are correlated with disease activity in rheumatoid arthritis

Objective. CD161 has been identified as a marker of human IL-17-producing T cells that are implicated in the pathogenesis of rheumatoid arthritis (RA). This study aimed to investigate the potential link between the percentage of CD161+ T cells and disease activity in RA patients. Methods. Peripheral blood (PB) from 54 RA patients and 21 healthy controls was evaluated. Paired synovial fluid (SF) (n = 17) was analyzed. CD161 expression levels on CD4+, CD8+, and CD4−CD8− T cells were assessed by flow cytometry. Results. The percentage of CD4+CD161+ T cells in RA SF was higher than RA PB, and it was positively correlated with DAS28, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). CD4−CD8−CD161+ T cell percentage was decreased in RA PB and was further reduced in RA SF, and its level in SF was inversely correlated with DAS28, ESR, and CRP. However, CD8+CD161+ T cell percentage was neither changed in RA PB and SF nor correlated with disease activity indices. Conclusion. An increased CD4+CD161+ T cell percentage and a decreased CD4−CD8−CD161+ T cell percentage are present in RA SF and are associated with disease activity, and the accumulation of CD4+CD161+ T cells in SF may contribute to the local inflammation of RA.