Increased plasma levels of IL-21 and IL-23 in spondyloarthritis are not associated with clinical and MRI findings

Pro-inflammatory cytokines in spondyloarthritis: a case-control study

OBJECTIVES

We aimed to determine the discriminative values of pro-inflammatory cytokines to distinguish spondyloarthritis patients from healthy subjects and to assess the association between these cytokines and spondyloarthritis characteristics.

METHODS

We conducted a case-control study, including 144 subjects matched for age and sex: 72 spondyloarthritis patients(G1) and 72 controls (G2). The disease activity was assessed using ASDAS-CRP and BASDAI. Structural damage was assessed using BASRI. The levels of interleukin (IL) IL-1, IL-6, IL-8, IL-17, IL-23, and tumor necrosis factor α(TNFα) were measured.

RESULTS

Each group included 57 men. The mean age was 44.84 ± 13.42 years. Except for IL-8, all cytokine levels were significantly higher in patients compared to controls (IL-1: p = 0.05, IL-6: p = 0.021, TNFα: p = 0.039, IL-17 and IL-23: p < 0.001). Cutoff values of IL-17 and IL-23 distinguishing patients in G1 from those in G2 were 17.6 and 7.96 pg/mL, respectively. TNFα level correlated to BASDAI (p = 0.029) and BASRI (p = 0.002). Multivariate analysis showed that structural damage was associated with the male gender (p = 0.017), longer disease duration (p = 0.038), and high disease activity (p = 0.044). Disease activity was associated with longer disease duration (p = 0.012) and increased IL-6 levels (p = 0.05).

CONCLUSION

Our study showed that IL-17 was the ablest to distinguish between spondyloarthritis patients and controls, suggesting that IL-17 may be helpful for the diagnosis of spondyloarthritis.

Joint together: The etiology and pathogenesis of ankylosing spondylitis

Spondyloarthritis (SpA) refers to a group of diseases with inflammation in joints and spines. In this family, ankylosing spondylitis (AS) is a rare but classic form that mainly involves the spine and sacroiliac joint, leading to the loss of flexibility and fusion of the spine. Compared to other diseases in SpA, AS has a very distinct hereditary disposition and pattern of involvement, and several hypotheses about its etiopathogenesis have been proposed. In spite of significant advances made in Th17 dynamics and AS treatment, the underlying mechanism remains concealed. To this end, we covered several topics, including the nature of the immune response, the microenvironment in the articulation that is behind the disease's progression, and the split between the hypotheses and the evidence on how the intestine affects arthritis. In this review, we describe the current findings of AS and SpA, with the aim of providing an integrated view of the initiation of inflammation and the development of the disease.

B Cell Involvement in the Pathogenesis of Ankylosing Spondylitis

Extensive research into ankylosing spondylitis (AS) has suggested the major role of genetics, immune reactions, and the joint-gut axis in its etiology, although an ultimate consensus does not yet exist. The available evidence indicates that both autoinflammation and T-cell-mediated autoimmune processes are actively involved in the disease process of AS. So far, B cells have received relatively little attention in AS pathogenesis; this is largely due to a lack of conventional disease-defining autoantibodies. However, against prevailing dogma, there is a growing body of evidence suggestive of B cell involvement. This is illustrated by disturbances in circulating B cell populations and the formation of auto-reactive and non-autoreactive antibodies, along with B cell infiltrates within the axial skeleton of AS patients. Furthermore, the depletion of B cells, using rituximab, displayed beneficial results in a subgroup of patients with AS. This review provides an overview of our current knowledge of B cells in AS, and discusses their potential role in its pathogenesis. An overarching picture portrays increased B cell activation in AS, although it is unclear whether B cells directly affect pathogenesis, or are merely bystanders in the disease process.

Pain and Fatigue in Patients With Ankylosing Spondylitis Treated With Tumor Necrosis Factor Inhibitors: Multinational Real-World Findings

BACKGROUND/OBJECTIVE

Patients with ankylosing spondylitis (AS) experience symptoms and comorbidities that impact their health-related quality of life (HRQoL) and ability to work. This real-world, global survey was conducted among AS patients receiving tumor necrosis factor inhibitors (TNFis) to evaluate both the frequency and severity of persistent symptoms, and the impact of pain and fatigue on HRQoL, employment status, and work activity.

METHODS

Patients with AS and their treating physicians from 13 countries across 5 continents completed questionnaires capturing demographics, patient symptoms, current disease status, HRQoL, current therapy, employment status, and Work Productivity and Activity Impairment.

RESULTS

Seven hundred five patients who had been receiving a TNFi for 3 months or more and completed both Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) pain and fatigue domains were included in the analysis; of these, 37.6% reported high BASDAI pain scores and 41.3% high BASDAI fatigue scores. Medical Outcomes Study-Short Form, 36-item version 2 domain, 5-dimensional EuroQoL Questionnaire, and 5-dimensional EuroQoL visual analog scale scores were significantly lower (p < 0.0001), and Work Productivity and Activity Impairment scores significantly higher (p < 0.0001), in patients with high levels of pain or fatigue than low levels.

CONCLUSIONS

Globally, levels of pain and fatigue remained high in AS patients receiving TNFi treatment, which were significantly associated with reduced HRQoL and work productivity. Such persistent symptoms in usual care suggest a substantial unmet need in AS pharmacologic and nonpharmacologic therapeutic pathways.

Utility of magnetic resonance imaging in Crohn's associated sacroiliitis: A cross-sectional study

OBJECTIVE

Prevalence of sacroiliitis in Crohn's disease (CD) is variable depending on defining criteria. This study utilized standardized sacroiliac joint (SIJ) magnetic resonance imaging (MRI) to identify sacroiliitis in CD patients and its association with clinical and serological markers.

METHODS

Consecutive adult subjects with CD prospectively enrolled from an inflammatory bowel disease clinic underwent SIJ MRI. Data collected included CD duration, history of joint/back pain, human leukocyte antigen-B27 status, Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index, Harvey Bradshaw Index (HBI) for activity of CD, Ankylosing Spondylitis Disease Activity Score, and various serologic markers of inflammation. Three blinded readers reviewed MRIs for active and structural lesions according to the Spondyloarthritis Research Consortium of Canada modules.

RESULTS

Thirty-three CD patients were enrolled: 76% female, 80% White, median age 36.4 years (interquartile range 27.2-49.0), moderate CD activity (mean HBI 8.8 ± SD 4.5). Nineteen subjects (58%) reported any back pain, 13 of whom had inflammatory back pain. Four subjects (12%) showed sacroiliitis using global approach and 6 (18%) met Assessment of SpondyloArthritis international Society MRI criteria of sacroiliitis. Older age (mean 51.2 ± SD 12.5 vs. 37.2 ± 14; P = .04), history of dactylitis (50.0% vs. 3.4%, P = .03) and worse BASMI (4.1 ± 0.7 vs. 2.4 ± 0.8, P ≤ .001) were associated with MRI sacroiliitis; no serologic measure was associated.

CONCLUSION

There were 12%-18% of CD patients who had MRI evidence of sacroiliitis, which was not associated with back pain, CD activity or serologic measures. This data suggests that MRI is a useful modality to identify subclinical sacroiliitis in CD patients.

Biomarker development for axial spondyloarthritis

The term axial spondyloarthritis (axSpA) encompasses a heterogeneous group of diseases that have variable presentations, extra-articular manifestations and clinical outcomes, and that will respond differently to treatments. The prototypical type of axSpA, ankylosing spondylitis, is thought to be caused by interaction between the genetically primed host immune system and gut microbiota. Currently used biomarkers such as HLA-B27 status, C-reactive protein and erythrocyte sedimentation rate have, at best, moderate diagnostic and predictive value. Improved biomarkers are needed for axSpA to assist with early diagnosis and to better predict treatment responses and long-term outcomes. Advances in a range of 'omics' technologies and statistical approaches, including genomics approaches (such as polygenic risk scores), microbiome profiling and, potentially, transcriptomic, proteomic and metabolomic profiling, are making it possible for more informative biomarker sets to be developed for use in such clinical applications. Future developments in this field will probably involve combinations of biomarkers that require novel statistical approaches to analyse and to produce easy to interpret metrics for clinical application. Large publicly available datasets from well-characterized case-cohort studies that use extensive biological sampling, particularly focusing on early disease and responses to medications, are required to establish successful biomarker discovery and validation programmes.

An update on serum biomarkers to assess axial spondyloarthritis and to guide treatment decision

Axial spondyloarthritis (axSpA) is a group of debilitating, chronic, rheumatic conditions characterized by inflammation and new bone formation, mainly involving the spine and the sacroiliac joints. The lack of biomarkers in axSpA is well known. Despite significant treatment advances in recent years thanks to the introduction of drugs with a new mode of action, such as new biologic and targeted synthetic disease-modifying antirheumatic drugs, no relevant improvement in the identification of disease biomarkers has been achieved. Common parameters, such as erythrocyte sedimentation rate and C-reactive protein, which are routinely used to measure systemic inflammation, are the sole markers available to date and are not adequate to assess disease activity in all patients. The aim of this study is to review the most promising serum biomarkers that may help treatment decision in axSpA via a proper assessment of disease activity and identification of negative prognostic factors.

Anti-tumor necrosis factor treatment increases both the Th17 and Th22 T helper subsets in spondyloarthritis

The aim was to examine anti-tumor necrosis factor α (anti-TNFα) therapy influence changes on Th17 and Th22 cells in patients with spondyloarthritis (SpA), and its correlation with changes in clinical and magnetic resonance imaging (MRI) activity and chronicity scores. The Th17 and Th22 cells were assessed at baseline, after 12 and 52 weeks of anti-TNFα therapy by flow cytometry (ClinicalTrials.gov NCT4682724). The percentages of both Th17 and Th22 cells were increased by 70% at baseline compared with healthy controls (both p < 0.01). During treatment, these two subsets increased further to be 170% (Th17) and 123% (Th22) above levels in healthy controls (both p < 0.01). The same subsets decrease their expression of IL-23R significantly during the observation period (p < 0.05). High levels of Th17 and Th22 cells at baseline were associated with the degree of chronic changes in the sacroiliac joints on MRI and a good clinical response to anti-TNFα treatment after one year. Plasma levels were not associated with clinical changes. Th17 cells, and Th22 subsets, increased during one year of anti-TNF-α therapy in SpA, regardless of their clinical improvement. This supports that both the Th17 and Th22 subsets could be involved in the progression in SpA.

Serological Biomarkers in Early Axial Spondyloarthritis During 24-Months Follow Up (Italian Arm of Space Study)

Objectives: The study aimed to evaluate biomarkers facilitating early axial-spondyloarthritis (axSpA) diagnosis and disease activity and imaging indices correlated. Materials and Methods: Seventy-five patients with low back pain (LBP) (≥3 months, ≤2 years, onset ≤45 years) participating in the Italian arm of the SpondyloArthritis-Caught-Early (SPACE) study underwent a physical examination, questionnaires, laboratory tests, spine, and sacroiliac joints (SIJ) X-rays and magnetic resonance imaging (MRI) at baseline and during a 24-months follow-up. Two expert rheumatologists formulated axSpA diagnosis and assessed fulfillment of Assessment of SpondyloArthritis International Society (ASAS) criteria. Disease activity and physical functioning were assessed using imaging, clinical, and serological indices. Spine and SIJ MRI and X-rays were scored independently by 2 readers following the Spondyloarthritis Research Consortium of Canada (SPARCC), mSASSS, and mNY-criteria. Patients were classified in accordance to ASAS criteria as: 21 patients classified according to axSpA imaging arm; 29 patients classified according to axSpA clinical ± imaging arm; 25 patients not fulfilling ASAS criteria. Results: At baseline biomarker levels were not significantly increased in any of the patient groups. Instead, a significant decrease of all functional and disease activity indices from baseline to 24 months was observed in all the three groups. In the same period, there were no significant variation in the serological markers values within each group. The correlations between IL-17 and IL-23 and clinical and functional indices were not significant. On the other hand, significant correlations were found between IL-22 and Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Patient Global Score (BASG1), Health Assessment Questionnaire (HAQ), Visual Analog Scale (VAS pain); MMP3 and mSASSS; MMP3 and hsCRP. Conclusions: Although not significantly higher in any of the cohorts, IL-22, MMP3, and hsCRP values correlated with some disease activity indices and with mSASSS. Further studies are warranted to confirm these preliminary findings.

Whodunit? The Contribution of Interleukin (IL)-17/IL-22-Producing γδ T Cells, αβ T Cells, and Innate Lymphoid Cells to the Pathogenesis of Spondyloarthritis

γδ T cells, αβ T cells, and innate lymphoid cells (ILCs) are capable of producing interleukin (IL)-17A, IL-17F, and IL-22. Among these three families of lymphocytes, it is emerging that γδ T cells are, at least in rodents, the main source of these key pro-inflammatory cytokines. γδ T cells were implicated in multiple inflammatory and autoimmune diseases, including psoriasis, experimental autoimmune encephalomyelitis and uveitis, colitis, and rheumatoid arthritis. Recent findings pointed toward a central role of γδ T cells in the pathogenesis of spondyloarthritis (SpA), a group of inflammatory rheumatic diseases affecting the axial skeleton. SpA primarily manifests as inflammation and new bone formation at the entheses, which are connecting tendons or ligaments with bone. In SpA patients, joint inflammation is frequently accompanied by extra-articular manifestations, such as inflammatory bowel disease or psoriasis. In humans, genome-wide association studies could link the IL-23/IL-17 cytokine axis to SpA. Accordingly, antibodies targeting IL-23/IL-17 for SpA treatment already showed promising results in clinical studies. However, the contribution of IL-17-producing γδ T cells to SpA pathogenesis is certainly not an open-and-shut case. Indeed, the cell types that are chiefly involved in local inflammation in human SpA still remain largely unclear. Some studies focusing on blood or synovium from SpA patients reported augmented IL-17-producing and IL-23 receptor-expressing γδ T cells, but other cell types might contribute as well. Here, we summarize the current understanding of how γδ T cells, αβ T cells, and ILCs contribute to the pathogenesis of human and experimental SpA.

Observational study of Interleukin-21 (IL-21) does not distinguish Kawasaki disease from other causes of fever in children

BACKGROUND

Kawasaki disease (KD) is a febrile childhood vasculitis of unknown etiology. The diagnosis is highly concerning as over a quarter of children who fail to receive timely treatment with intravenous immunoglobulin (IVIG) will develop coronary aneurysms. Diagnosis relies on proper symptomatology and is supported by non-specific markers of inflammation. Previous studies have identified elevated plasma levels of interleukin-21 (IL-21) as a sensitive and specific biomarker in KD. The aim of this study is to assess the validity of IL-21 as a diagnostic biomarker for KD in febrile children in North America.

METHODS

Plasma samples were collected from children who presented to an urban Emergency Department in North America. IL-21 levels were measured using commercial ELISA kits in 12 KD versus 60 controls subjects.

RESULTS

Our study shows that IL-21 levels were non-specifically elevated across all febrile children, irrespective of KD diagnosis. Length of fever prior to sample collection does not correlate with IL-21 levels. Other inflammatory markers and laboratory values were also compared to IL-21 and show no significant correlation.

CONCLUSIONS

Since IL-21 is elevated non-specifically in this cohort, our data supports that IL-21 is not an appropriate biomarker for diagnosis of KD in North American pediatric populations.

Serum prolidase level in ankylosing spondylitis: low serum levels as a new potential gold standard biomarker for disease activity

Ankylosing spondylitis (AS) is a chronic inflammatory disorder that mainly affects the sacroiliac joints and axial skeleton. The aim of this study was to assess serum prolidase level (SPL) and its association with disease activity in patients with AS. This prospective study included 75 AS patients. Thirty age- and gender-matched healthy controls were enrolled. AS patients were considered as active if BASDAI score was ≥4 or inactive if BASDAI score was <4. There were 34 AS patients in the active group and 41 AS patients in the inactive group. Anti-TNF-monoclonal antibody treatment was started in patients in the active group. These active patients were reassessed 6 months later. BASDAI, ASDAS, visual analogue scale, short-form-general health survey questionnaire, C-reactive protein, erythrocyte sedimentation rate and SPL were measured in all AS patients before and after treatment. The SPL was significantly lower in inactive AS patients than in control group, and also, SPL was significantly lower in active AS patients than in inactive patients. All activity parameters were successful in separating active and inactive AS patients. However, the only parameter that could distinguish active patients from inactive patients was prolidase. The optimum cutoff point of SPL to identify patients with active AS was 23.13 ng/mL with sensitivity, specificity, positive predictive value and negative predictive value of 100 %. Serum prolidase level was successful in measuring disease activity and had as high sensitivity and specificity as BASDAI and was superior to other activity parameters.

Interleukin-23 in early disease development in rheumatoid arthritis

OBJECTIVES

To investigate the levels of interleukin (IL)-23 in patients with early rheumatoid arthritis (eRA) and the effect of anti-tumour necrosis factor (anti-TNF)-α treatment on IL-23 levels.

METHOD

Treatment-naïve eRA patients from the OPERA cohort were included (n = 151). Patients were randomized to methotrexate (MTX) plus adalimumab (ADA; n = 75) or MTX plus placebo-ADA (PLA; n = 76). Plasma samples were obtained at baseline and at months 3, 6, and 12 together with values for C-reactive protein (CRP), the 28-joint Disease Activity Score based on CRP (DAS28CRP), scores on the Clinical Disease Activity Index (CDAI) and the Simplified Disease Activity Index (SDAI), visual analogue scale (VAS) for pain/fatigue/physician global and total Sharp/van der Heijde score (TSS). IL-23 was measured at each time point.

RESULTS

IL-23 levels decreased significantly in the ADA group from 20.6 pg/mL (IQR 13.1-32.7 pg/mL) at baseline to 18 pg/mL (IQR 7.2-25.0 pg/mL) at 12 months (p < 0.01). No significant decrease in IL-23 level was observed in the PLA group. No associations between baseline IL-23 levels and measures of disease activity (DAS28CRP, CRP, CDAI, or SDAI) at 12 or 24 months were present in the treatment groups. Baseline IL-23 correlated inversely with changes in TSS and symptom duration before diagnosis.

CONCLUSIONS

Our data show increased baseline levels and a significant decrease in IL-23 levels in eRA patients treated with anti-TNF-α. The inverse correlation with duration of symptoms before diagnosis supports the importance of IL-23 in the preclinical disease development of RA.

Regulation of Memory T Cells by Interleukin-23

Interleukin-23 (IL-23), a member of the IL-12 family of cytokines, is a heterodimeric cytokine. It is composed of subunits p40 (shared with IL-12) and p19 (an IL-12 p35-related subunit) and is secreted by several types of immune cells, such as natural killer cells and dendritic cells. The IL-23 receptor is composed of the subunit IL-12Rβ1 and the IL-23-specific subunit IL-23R. The binding of IL-23 to its specific cell surface receptor regulates a number of functions, including proliferation and differentiation of cells and secretion of cell factors. Memory T cells are a subset of T cells that secrete numerous important cell factors, and they function in the immune response to infection and diseases like cancer, autoimmune disease and bronchial asthma. IL-23R is expressed on the surface of memory T cells, which suggests that it can specifically regulate memory T cell function. IL-23 has been widely used as a clinical indicator in immune-related diseases and shows potential for use in disease treatment. Here we review the current progress in the study of the role of IL-23 in the regulation of memory T cells.

Circulating levels of Th1 and Th2 chemokines in patients with ankylosing spondylitis

OBJECTIVE

Although chemokines are critical elements for the selective attraction and activation of various leukocyte subsets in the inflammatory process, there are few findings concerning T helper (Th) 1 or Th2 chemokines in ankylosing spondylitis (AS). This study was designed to determine whether serum levels of chemokines that are preferentially chemotactic for Th1 (IFN-gamma-inducible protein-10, IP-10/CXCL10) and Th2 (thymus and activation regulated chemokine, TARC/CCL17) and (macrophage derived chemokine, MDC/CCL22) cells were elevated and whether they correlated with the clinical features in patients with AS.

METHODS

Forty-two patients with axial AS and 25 healthy controls were enrolled into the study. Serum levels of chemokines (IP-10, TARC and MDC) and cytokines (IFN-γ, TNF-α and IL-4) were examined using ELISA. The disease activity was evaluated by Ankylosing Spondylitis Disease Activity Score (ASDAS). Serum levels of IgG, IgA, IgM, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured.

RESULTS

Serum chemokine levels of IP-10, TARC and MDC were significantly higher in patients with AS than those in healthy controls. Serum cytokine levels of IFN-γ, TNF-α were also significantly increased, but the levels of IL-4 were not. Furthermore, IP-10 levels in AS patients correlated with ESP, CRP and ASDAS, while the levels of TARC and MDC did not correlate with these clinic indexes. Correlation analysis between the levels of chemokines and cytokines revealed a positive correlation between IP-10 and TNF-α. The levels of both Th1 and Th2 chemokines decreased under blockade of TNF-α.

CONCLUSION

Our results suggest that both a Th1 chemoattractant IP-10 and Th2 chemoattractants, TARC and MDC, cooperatively play a role in the development of AS.

Mediators of inflammation and bone remodeling in rheumatic disease

Remodeling of bone is a continuous process that occurs throughout life. Under normal physiologic conditions, bone-resorbing osteoclasts and bone-forming osteoblasts are tightly coupled and regulated to ensure proper balance, such that there is no net change in bone mass. However, inflammation perturbs normal bone homeostasis. The impact of inflammation on bone is dependent upon the anatomic site affected, cell types, factors and cytokines present in the local microenvironment, and local mechanical forces. Cytokines are central to the pathogenesis of inflammation-induced bone loss and contribute to the uncoupling of osteoclast-mediated bone resorption and osteoblast-mediated bone formation, thereby disrupting normal remodeling. In this review, we will discuss the effects of cytokines on bone in two settings, rheumatoid arthritis and spondyloarthritis, a disease category that includes ankylosing spondylitis, psoriatic arthritis, reactive arthritis, inflammatory bowel disease, and juvenile onset spondyloarthropathy. The outcome for bone in these disease settings is quite different, and an understanding of the pathogenic mechanisms leading to the net impact on bone has been essential in developing new therapeutic approaches to bone health in these diseases.

Biomarkers for diagnosis, monitoring of progression, and treatment responses in ankylosing spondylitis and axial spondyloarthritis

With the growing awareness of the impact of chronic back pain and axial spondyloarthritis and recent breakthroughs in genetics and the development of novel treatments which may impact best on early disease, the need for markers that can facilitate early diagnosis and profiling those individuals at the highest risk for a bad outcome has never been greater. The genetic basis of ankylosing spondylitis has been considerably advanced, and HLA-B27 testing has a role in the diagnosis. Knowledge is still incomplete of the rest of the genetic contribution to disease susceptibility, and it is likely premature to use extensive genetic testing (other than HLA-B27) for diagnosis. Serum and plasma biomarkers have been examined extensively in assessing disease activity, treatment response, and as predictors or radiographic severity. For assessing disease activity, other than C-reactive protein and erythrocyte sedimentation rate, the most work has been in examining cytokines (particularly interleukin 17 and 23), matrix metalloproteinase (MMP) markers (particularly MMP3). For assessing those at the highest risk for radiographic progression, biomarkers of bony metabolism, cartilage and connective tissue degradation products, and adipokines have been most extensively assessed. The problem is that no individual biomarkers has been reproducibly shown to assess disease activity or predict outcome, and this area still remains an unmet need, of relevance to industry stakeholders, to regulatory bodies, to the healthcare system, to academic investigators, and finally to patients and providers.

Th17 cells in autoimmune and infectious diseases

The view of CD4 T-cell-mediated immunity as a balance between distinct lineages of Th1 and Th2 cells has changed dramatically. Identification of the IL-17 family of cytokines and of the fact that IL-23 mediates the expansion of IL-17-producing T cells uncovered a new subset of Th cells designated Th17 cells, which have emerged as a third independent T-cell subset that may play an essential role in protection against certain extracellular pathogens. Moreover, Th17 cells have been extensively analyzed because of their strong association with inflammatory disorders and autoimmune diseases. Also, they appear to be critical for controlling these disorders. Similar to Th1 and Th2 cells, Th17 cells require specific cytokines and transcription factors for their differentiation. Th17 cells have been characterized as one of the major pathogenic Th cell populations underlying the development of many autoimmune diseases, and they are enhanced and stabilized by IL-23. The characteristics of Th17 cells, cytokines, and their sources, as well as their role in infectious and autoimmune diseases, are discussed in this review.

Increased frequency of circulating follicular helper T cells in patients with ankylosing spondylitis

OBJECTIVE

The relationship between circulating follicular helper T (Tfh) cells and ankylosing spondylitis (AS) remains unclear. The aims of our study were to measure the levels of circulating Tfh cells and several related parameters in patients with AS, and examine the correlation of these factors with disease activity.

METHODS

We designated CD4 + CXCR5 + ICOS+ T cells as circulating Tfh cells. The percentage of circulating Tfh cells was detected using flow cytometry. Plasma IL-21 and immunoglobulin (IgA, IgM, and IgG) levels were quantified using enzyme-linked immunosorbent assay in 60 AS patients and 60 healthy controls (HC).

RESULTS

The percentage of circulating Tfh cells was increased in AS patients compared with that in HC. As AS patients were divided into active and inactive groups, the percentage of circulating Tfh cells was significantly increased in active group compared with both inactive group and HC. Plasma IL-21 and immunoglobulin levels were elevated in AS patients, and the differences were significant except IgG. In addition, the percentage of circulating Tfh cells was positively correlated with Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and plasma IL-21 levels were positively correlated with plasma immunoglobulin levels. But neither circulating Tfh cells nor BASDAI was significantly correlated with plasma IL-21 and immunoglobulin levels in AS patients, with the exception of significant correlation between BASDAI and plasma IgM levels in active AS patients.

CONCLUSION

Our study has shown the increased percentage of circulating Tfh cells correlated with disease activity, and the high plasma IL-21 levels were associated with high plasma immunoglobulin levels in patients with AS, indicating that the circulating Tfh cells may be associated with the development of AS.

Higher frequency of peripheral blood interleukin 21 positive follicular helper T cells in patients with ankylosing spondylitis

OBJECTIVE

The role of follicular Th (TFH) cells remains unclear in the pathogenesis of ankylosing spondylitis (AS). Our study examined the frequency of different subsets of circulating CXCR5+CD4+ T cells in patients with AS before and after receiving therapy.

METHODS

Percentages of peripheral blood inducible costimulator (ICOS)+, programmed death 1 (PD-1)+, and interleukin 21 (IL-21)+ CXCR5+CD4+ T cells in 26 patients with AS and 12 healthy controls (HC) were examined by flow cytometry, and the disease activity of individual patients was measured by Bath AS Disease Activity Index (BASDAI). The concentrations of serum IL-21, IgG, IgA, IgM, and C-reactive protein (CRP) were examined and the values of erythrocyte sedimentation rate (ESR) were measured. The potential association among these measures was analyzed.

RESULTS

In comparison with that in HC, significantly increased percentages of CXCR5+CD4+, CXCR5+CD4+PD-1+, and CXCR5+CD4+IL-21+, but not CXCR5+CD4+ICOS+ and PD-1+ICOS+CXCR5+CD4+ T cells, and elevated concentrations of serum IL-21 were detected in patients with AS (p = 0.001, p = 0.012, p < 0.001, p = 0.233, p = 0.216, p < 0.001, respectively). Treatment with meloxicam, thalidomide, and etanercept for 1 month significantly reduced percentages of IL-21+CXCR5+CD4+ T cells and concentrations of serum IL-21 (p < 0.001, p < 0.001, respectively), accompanied by significantly minimized disease activity in drug responders, but not in the drug nonresponders. Further, percentages of IL-21+CXCR5+CD4+ T cells were positively correlated with BASDAI in patients (r = 0.6, p = 0.0012) and in the drug-responders 1 month after treatment (r = 0.68, p = 0.005), while the percentages of PD-1+CXCR5+CD4+ T cells were negatively correlated with BASDAI (r = -0.58, p = 0.0018).

CONCLUSION

These data suggest that IL-21+CXCR5+CD4+ T cells may be associated with development of AS and that the frequency of IL-21+CXCR5+CD4+ T cells may be a biomarker for evaluation of disease activity and drug responses in patients with AS, particularly in drug-responding patients.

Elevated Serum Levels of IL-21 in Kawasaki Disease

Purpose

The serum level of immunoglobulin (Ig)E has been reported to be elevated in patients with Kawasaki disease (KD). We investigated whether interleukin (IL)-21, rather than IL-4, could be related to elevated serum levels of IgE in KD.

Methods

Sera from 48 patients with KD and 12 controls with high fever were collected to determine the level of IgE using an immunoassay system and the levels of IL-4 and IL-21 were determined using enzyme-linked immunosorbent assay kits.

Results

The median IL-21 level of KD patients was significantly elevated, at 499.5 pg/mL (range: <62.5-1,544 pg/mL), whereas that of controls was <62.5 pg/mL (<62.5-825 pg/mL; P<0.001). The median IL-4 level of KD patients was not elevated (4.0 pg/mL; 2.1-7.6 pg/mL). The median level of total IgE in KD patients was 58.0 IU/mL (5-1,109 IU/mL). No statistically significant correlation was found between IL-21 and total IgE levels (Spearman's R=0.2; P=0.19).

Conclusions

Patients with KD have elevated levels of IL-21 in the serum. IL-21 may play a role in the pathogenesis of KD.