Association of mucosal-associated invariant T cells with different disease phases of polymyalgia rheumatica

The Impact of IL-17A Inhibition in Rheumatic and Musculoskeletal Diseases: Current Insights and Future Prospects

Interleukin-17A (IL-17A) plays a pivotal role in many rheumatic immune-mediated inflammatory diseases. Targeting the IL-17 pathway has transformed the way psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) are managed, with a number of IL-17A inhibitors now available for treating rheumatic and musculoskeletal diseases. This narrative review will describe the opportunities presented by novel imaging techniques in understanding the metabolic and mechanical changes that characterize the pathogenesis of PsA and axSpA. It will look at the current consensus definitions of early disease in PsA and axSpA, present evidence for the benefit of early treatment, and highlight the gaps in current knowledge. Finally, it will describe novel treatment targets to address the unmet needs in giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) and discuss the potential role of IL-17A inhibition in treating GCA and PMR.

Definitions of and instruments for disease activity, remission and relapse in polymyalgia rheumatica: a systematic literature review

OBJECTIVE

To perform a systematic literature review on definitions and instruments used to measure remission, relapse and disease activity in polymyalgia rheumatica (PMR), to inform an OMERACT project to endorse instruments for these outcomes.

METHODS

A search of Pubmed/MEDLINE, EMBASE, CINAHL, Cochrane and Epistemonikos was performed May 2021 and updated August 2023. Qualitative and quantitative studies published in English were included if they recruited people with isolated PMR regardless of treatment. Study selection and data extraction was performed independently by two investigators and disagreement was resolved through discussion. Data extracted encompassed definitions of disease activity, remission and relapse, and details regarding the instruments used to measure these outcomes.

RESULTS

From the 5718 records, we included 26 articles on disease activity, 36 on remission and 53 on relapse; 64 studies were observational and 15 interventional, and none used qualitative methods. Some heterogeneity was found regarding definitions and instruments encompassing the domains pain, stiffness, fatigue, laboratory markers (mainly acute phase reactants), and patient and physician global assessment of disease activity. However, instruments for clinical signs were often poorly described. Whilst measurement properties of the polymyalgia rheumatica activity score (PMR-AS) have been assessed, data to support its use for measurement of remission and relapse are limited.

CONCLUSION

Remission, relapse and disease activity have been defined heterogeneously in clinical studies. Instruments to measure these disease states still need to be validated. Qualitative research is needed to better understand the concepts of remission and relapse in PMR.

REVIEW REGISTRATION

PROSPERO identification: CRD42021255925.

Why is polymyalgia rheumatica a disease of older adults? Explanations through etiology and pathogenesis: a narrative review

Polymyalgia rheumatica is one of the most common inflammatory rheumatic conditions in older adults. The disease is characterized by pain and stiffness in the shoulder and pelvic girdle. Polymyalgia rheumatica is almost always observed in adults over the age of 50. The current article aimed to provide explanations for the age preference of polymyalgia rheumatica by reviewing the literature regarding disease etiology and pathogenesis. Potential factors related to the association between polymyalgia rheumatica and aging include immunosenescence/inflammaging, increased risk of infections by aging, endocrinosenescence, and age-related changes in gut microbiota. These factors and their potential contributions to immune-mediated inflammation will be discussed.

Mucosal-associated invariant T cells display both pathogenic and protective roles in patients with inflammatory bowel diseases

An important subtype of the innate-like T lymphocytes is mucosal-associated invariant T (MAIT) cells expressing a semi-invariant T cell receptor α (TCR-α) chain. MAIT cells could be activated mainly by TCR engagement or cytokines. They have been found to have essential roles in various immune mediated. There have been growing preclinical and clinical findings that show an association between MAIT cells and the physiopathology of inflammatory bowel diseases (IBD). Of note, published reports demonstrate contradictory findings regarding the role of MAIT cells in IBD patients. A number of reports suggests a protective effect, whereas others show a pathogenic impact. The present review article aimed to explore and discuss the findings of experimental and clinical investigations evaluating the effects of MAIT cells in IBD subjects and animal models. Findings indicate that MAIT cells could exert opposite effects in the course of IBD, including an anti-inflammatory protective effect of blood circulating MAIT cells and an effector pathogenic effect of colonic MAIT cells. Another important finding is that blood levels of MAIT cells can be considered as a potential biomarker in IBD patients.

Emerging Roles of Mucosal-Associated Invariant T Cells in Rheumatology

Mucosal-associated invariant T (MAIT) cells are an unconventional T cell subset expressing a semi-invariant TCR and recognize microbial riboflavin metabolites presented by major histocompatibility complex class 1-related molecule (MR1). MAIT cells serve as innate-like T cells bridging innate and adaptive immunity, which have attracted increasing attention in recent years. The involvement of MAIT cells has been described in various infections, autoimmune diseases and malignancies. In this review, we first briefly introduce the biology of MAIT cells, and then summarize their roles in rheumatic diseases including systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren’s syndrome, psoriatic arthritis, systemic sclerosis, vasculitis and dermatomyositis. An increased knowledge of MAIT cells will inform the development of novel biomarkers and therapeutic approaches in rheumatology.

Measurement properties of the PolyMyalgia Rheumatica Activity Score (PMR-AS): a systematic literature review

Objective

To perform a COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) based Systematic Literature Review of measurement properties of the Polymyalgia Rheumatica Activity Score (PMR-AS).

Methods

Pubmed, EMBASE, and CINAHL were broadly searched. English full text articles, with (quantitative) data on at least 5 PMR patients using the PMR-AS were selected. Seven hypotheses for construct validity and three for responsiveness, concerning associations with erythrocyte sedimentation rate, physical function, quality of life, clinical disease states, ultrasound, and treatment response, were formulated. Articles usable to assess - COSMIN based - structural validity, internal consistency, reliability, measurement error, or hypotheses on construct validity or responsiveness were selected and assessed based on COSMIN criteria.

Results

From the 26 articles using the PMR-AS we were able to use 12 articles. Structural validity, internal consistency, construct validity, and responsiveness were assessed in one, two, eight, and three articles respectively. Insufficient evidence was found to confirm structural validity and internal consistency. No data was found on reliability or measurement error. Although 60% and 67% of hypotheses tested for construct validity and responsiveness were confirmed respectively, there was insufficient evidence to meet criteria for good measurement properties.

Conclusion

Whilst there is some promising evidence for construct validity and responsiveness of the PMR-AS, it is lacking for other properties and overall falls short of criteria for good measurement properties. Therefore, further research is needed to assess its role in clinical research and care.

New-onset Polymyalgia Rheumatica Following the Administration of the Pfizer-BioNTech COVID-19 Vaccine

We herein report the case of an 80-year-old Japanese woman who presented to our hospital with bilateral pain in the shoulders and hips lasting for a month since 2 days after the second dose of the BNT162b2 COVID-19 vaccine. Her physical findings, laboratory data, and ultrasonographic findings of bilateral biceps tenosynovitis and lateral subacromial bursitis were consistent with a diagnosis of polymyalgia rheumatica (PMR). She was successfully treated with oral prednisolone 15 mg/day. Although a causal relationship could not be definitively confirmed, PMR should be considered as a differential diagnosis in cases of persistent myalgia after administration of the BNT162b2 vaccine.

Immune system activation in polymyalgia rheumatica: Which balance between autoinflammation and autoimmunity? A systematic review

BACKGROUND AND AIM

Polymyalgia rheumatica (PMR) is an inflammatory rheumatic disease that is common in elderly people. Its classification in the spectrum of autoinflammatory and autoimmune diseases is difficult because of its only partially understood immune-mediated mechanisms. The literature concerning the innate and adaptive immune system activation in PMR was systematically reviewed highlighting the relative weight of autoinflammation and autoimmunity in its pathogenesis and disease progression.

METHODS

A literature search on PubMed Central and Embase scientific databases was performed by two independent reviewers. To be eligible, the studies needed to fully satisfy our initial PICO framework: a primary diagnosis of PMR as a population, the search for immune/inflammatory cells, cytokines and autoantibodies as an intervention, a control group consisting in healthy controls, patients with other inflammatory rheumatic diseases or PMR patients in remission after treatment and as outcomes the results of the investigations in the analyzed tissue samples. The most relevant data of the included papers were extracted by using a standardized template.

RESULTS

Of the 933 screened abstracts, 52 papers were included in the systematic review and categorized depending on their primary research objectives. The hyper-activity of neutrophils and monocytes, expressing toll-like receptor 7 in active disease, an impaired phagocytosis and endothelial dysfunction, as well as an increased count of innate T cells in patients with remission emerged among the major derangements of the innate immune response in PMR. Among the cytokines profile, interleukin-6 plays a key role but other pro-inflammatory mediators and angiogenesis markers such as chemokines, B-cell activating factor, vascular endothelial growth factor and angiopoietins seem to be involved in refractory or glucocorticoid-resistant PMR. The aberrant adaptive immune response was documented by tissue and serum findings of polarized T cells towards T helper 1 and 17 phenotypes, an increased expression of immunosenescent surface markers and a downregulated immunoregulatory response. The altered distribution of peripheral B cells, detected during active disease, suggested their peripheral migration towards unidentified sites. The interaction between innate and adaptive immune response was documented by a synovial infiltrate of macrophages and T cells. Despite multiple autoantibodies have been detected in PMR patients, none proved to correlate with disease activity seeming to be reactive to the marked inflammation or antigenic determinants provided by environmental triggers or tissue/cell damage.

CONCLUSIONS

The complex network between innate and adaptive immune system in PMR is supported by findings at molecular and cellular levels. By considering both the ends of the pathophysiological spectrum of immune-mediated rheumatic diseases, PMR may be regarded as an inflammatory immune-mediated disease with mixed mechanisms in a background of genetic and epigenetic factors together with immunological and endocrine senescence.

Characteristics of mucosal-associated invariant T cells and their roles in immune diseases

Mucosal-associated invariant T (MAIT) cells are a subset of innate-like T cells that express a semi-invariant T cell receptor and are restricted by the molecule major histocompatibility complex class I-related molecule 1 (MR1). MAIT cells recognize biosynthetic derivatives of the riboflavin synthesis pathway present in microbes. MAIT cells have attracted increased interest related to various immune responses because of their unique features including their abundance in humans, nonpeptidic antigens, and ability to respond to antigenic and non-antigenic stimuli. The numbers of circulating MAIT cells are decreased in many immune diseases such as multiple sclerosis, systemic lupus erythematosus, and inflammatory bowel diseases. However, the remaining MAIT cells have an increased cytokine-producing capacity and activated status, which is related to disease activity. Additionally, MAIT cells have been observed at sites of inflammation including the kidneys, synovial fluid and intestinal mucosa. These findings suggest their involvement in the pathogenesis of immune diseases. In this mini-review, we summarize the recent findings of MAIT cells in human immune diseases and animal models, and discuss their role and potential as a therapeutic target.

Mucosal-associated invariant T cells in Giant Cell Arteritis

This study aimed to assess the implication of mucosal-associated invariant T (MAIT) cells in GCA. Blood samples were obtained from 34 GCA patients (before and after 3 months of treatment with glucocorticoids (GC) alone) and compared with 20 controls aged >50 years. MAIT cells, defined by a CD3⁺CD4^-TCRγδ^-TCRVα7.2⁺CD161⁺ phenotype, were analyzed by flow cytometry. After sorting, we assessed the ability of MAIT cells to proliferate and produce cytokines after stimulation with anti CD3/CD28 microbeads or IL-12 and IL-18. MAIT were stained in temporal artery biopsies (TAB) by confocal microscopy. MAIT cells were found in the arterial wall of positive TABs but was absent in negative TAB. MAIT frequency among total αβ-T cells was similar in the blood of patients and controls (0.52 vs. 0.57%; P = 0.43) and not modified after GC treatment (P = 0.82). Expression of IFN-γ was increased in MAIT cells from GCA patients compared to controls (44.49 vs. 32.9%; P = 0.029), and not modified after 3 months of GC therapy (P = 0.82). When they were stimulated with IL-12 and IL-18, MAIT from GCA patients produced very high levels of IFN-γ and displayed a stronger proliferation compared with MAIT from controls (proliferation index 3.39 vs. 1.4; P = 0.032). In GCA, the functional characteristics of MAIT cells are modified toward a pro-inflammatory phenotype and a stronger proliferation capability in response to IL-12 and IL-18, suggesting that MAIT might play a role in GCA pathogenesis. Our results support the use of treatments targeting IL-12/IL-18 to inhibit the IFN-γ pathway in GCA.