Behçet's disease: immunological relevance with arthritis of ankylosing spondylitis

T cells in ocular autoimmune uveitis: Pathways and therapeutic approaches

Autoimmune uveitis is a non-infectious intraocular condition that affects the uveal tract of the eye and threatens vision if not treated properly. Increasing evidence suggests that activated CD4⁺ T cells are associated with progressive and permanent destruction of photoreceptors in ocular autoimmune diseases. As such, the purpose of this review is to offer an overview of the role of CD4⁺ T cells in autoimmune uveitis as well as a justification for the current development and assessment of innovative autoimmune uveitis medications targeting CD4⁺ T cells. With an emphasis on T helper (Th)17, Th1, and Th2 cells, follicular helper CD4⁺ T cells, and regulatory T cells, this review presents a summary of recent research related to the pathways and signaling that encourage CD4⁺ T cells to develop into specialized effector cells. We also describe immunotherapeutic approaches based on CD4⁺ T cell subsets and their potential as therapeutic agents for autoimmune disorders.

The Role of Natural Killer Cells in Autoimmune Diseases

Natural killer (NK) cells, the large granular lymphocytes differentiated from the common lymphoid progenitors, were discovered in early 1970's. They are members of innate immunity and were initially defined by their strong cytotoxicity against virus-infected cells and by their important effector functions in anti-tumoral immune responses. Nowadays, NK cells are classified among the recently discovered innate lymphoid cell subsets and have capacity to influence both innate and adaptive immune responses. Therefore, they can be considered as innate immune cells that stands between the innate and adaptive arms of immunity. NK cells don't express T or B cell receptors and are recognized by absence of CD3. There are two major subgroups of NK cells according to their differential expression of CD16 and CD56. While CD16+CD56dim subset is best-known by their cytotoxic functions, CD16-CD56bright NK cell subset produces a bunch of cytokines comparable to CD4+ T helper cell subsets. Another subset of NK cells with production of interleukin (IL)-10 was named as NK regulatory cells, which has suppressive properties and could take part in immune-regulatory responses. Activation of NK cells is determined by a delicate balance of cell-surface receptors that have either activating or inhibitory properties. On the other hand, a variety of cytokines including IL-2, IL-12, IL-15, and IL-18 influence NK cell activity. NK-derived cytokines and their cytotoxic functions through induction of apoptosis take part in regulation of the immune responses and could contribute to the pathogenesis of many immune mediated diseases including ankylosing spondylitis, Behçet's disease, multiple sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus and type-1 diabetes. Dysregulation of NK cells in autoimmune disorders may occur through multiple mechanisms. Thanks to the rapid developments in biotechnology, progressive research in immunology enables better characterization of cells and their delicate roles in the complex network of immunity. As NK cells stand in between innate and adaptive arms of immunity and "bridge" them, their contribution in inflammation and immune regulation deserves intense investigations. Better understanding of NK-cell biology and their contribution in both exacerbation and regulation of inflammatory disorders is a requisite for possible utilization of these multi-faceted cells in novel therapeutic interventions.

Clinical Findings of Ankylosing Spondylitis With and Without Human Leukocyte Antigen (HLA)-B27 and HLA-B51

Introduction: Ankylosing spondylitis (AS) and Behçet’s disease are known to be associated with the human leukocyte antigen (HLA)-B27 and HLA-B51 genes, respectively. However, many of their clinical findings―including articular and extra-articular symptoms―are similar, making diagnosis a challenge in the early stage of the disease. The aim of this study was to investigate the differences in clinical findings of AS patients with and without the HLA-B27 gene. Materials and Methods: We performed a retrospective chart review of 151 AS patients. The following clinical findings were evaluated: oral ulcer, genital ulcer, skin manifestation, uveitis, peripheral arthritis; and gastrointestinal, cardiac and pulmonary involvement. Patients were divided into 4 groups based on absence or presence of the HLA-B27 and HLA-B51 genes. The number of patients with each clinical finding was subsequently examined in each group. Results: The incidence of uveitis was significantly higher in the HLA-B27-positive group (P = 0.004); however, other clinical findings did not differ significantly according to the absence or presence of the HLA-B27 gene. There were no significant differences in the clinical findings of patients with positive and negative HLA-B51. Conclusion: HLA-B27 was associated with the development of uveitis but not with other clinical findings or disease activity in AS patients. HLA-B51 was not associated with the clinical findings or disease activity of AS. Key words: Axial spondyloarthritis, Behçet’s disease, Uveitis

Risk of immune-mediated inflammatory diseases in newly diagnosed ankylosing spondylitis patients: a population-based matched cohort study

Objective

To investigate the risk of immune-mediated inflammatory diseases (IMIDs) in patients with ankylosing spondylitis (AS).

Methods

Using 2003–2012 claims data from the Taiwanese National Health Insurance Research Database, we identified 30,911 newly diagnosed AS patients requiring medical therapy from 2006 to 2012. In addition, we randomly selected 309,110 non-AS individuals matching (1:10) the AS patients with regard to age, sex and the year of the index date. After excluding subjects with the corresponding prior IMIDs, we calculated the incidence rates (IRs) of various IMIDs in the AS and non-AS cohorts and estimated the hazard ratios (HRs) with 95% confidence intervals after adjusting for age, sex, the Charlson comorbidity index, the frequency of ambulatory visits during the follow-up period and medications. We conducted sensitivity analyses by excluding those who developed IMIDs within 3 months after the index date.

Results

In the follow-up period, we found that newly diagnosed AS patients had significantly increased risks of acute anterior uveitis, psoriasis, Sjögren’s syndrome, thromboangiitis obliterans, Behcet’s disease and sarcoidosis. However, the risk of Sjögren’s syndrome did not increase in AS patients in the sensitivity analysis. In the same period, this study found no significant differences in the risks of Crohn’s disease, ulcerative colitis, systemic lupus erythematosus, systemic sclerosis, dermatomyositis, polymyositis, pemphigus and vitiligo between newly diagnosed AS patients and non-AS individuals. AS patients had a significantly reduced risk of rheumatoid arthritis.

Conclusion

Newly diagnosed Taiwanese AS patients had increased risks of acute anterior uveitis, psoriasis, thromboangiitis obliterans, Behcet’s disease and sarcoidosis, but a reduced risk of rheumatoid arthritis.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1980-1) contains supplementary material, which is available to authorized users.

Higher Frequencies of Lymphocytes Expressing the Natural Killer Group 2D Receptor in Patients With Behçet Disease

Behçet disease (BD) is an inflammatory systemic disease with a fluctuating course, which can affect the skin, eyes, central nervous system, musculoskeletal, gastrointestinal, and vascular systems. No laboratory tests are currently available for the diagnosis of BD and monitoring disease activity. Moreover there is a lack of knowledge on BD pathogenesis. This study focused on circulating Natural Killer (NK), NKT and T cells evaluated as CD3^neg CD56^pos, CD3^pos CD56^pos, and CD3^pos CD56^neg. Peripheral blood mononuclear cells (PBMCs) were collected from 38 BD patients and 20 healthy controls (HC). The frequencies of NK, NKT, and T cells expressing CD16, CD69, NKG2D, Nkp30, Nkp46, and NKG2A were assessed by flow cytometry. Cytotoxic potential of NK cells was evaluated by flow cytometry as the percentage of cells expressing the degranulation marker CD107a after incubation with K562 cells. The levels of 27 cytokines were determined in plasma with a multiplex bead-based assay. Higher percentages of NK, NKT, and T cells expressing NKG2D were detected in PBMCs of BD patients than HC. ROC curve analysis showed that the evaluation of NKG2D^pos NK, NKT, and T cell percentages discriminated between BD patients and HC. Moreover, there was a positive correlation between the BD Current Activity Form (BDCAF) scores and the frequencies of NKG2D^pos NK and NKT cells. A higher frequency of NK cells expressing CD107a was induced in PBMCs from BD patients than HC after incubation with K562 cells. Concentrations of IL-5, IL-6, IL-10, IL-13, IP-10, and MIP-1β were higher in plasma of BD patients than HC. Monitoring the frequencies of NKG2D^pos lymphocytes could help the clinicians in BD patients management. In addition, the increased expression of NKG2D in BD patients is likely involved in disease pathogenesis.

Cytokine, C-Reactive Protein, and Heat Shock Protein mRNA Expression Levels in Patients with Active Behçet's Uveitis

Background

To investigate the gene expression levels of interleukin 10 (IL10), IL18, interferon gamma (IFNG), IFN-gamma receptor (IFNGR), C-reactive protein (CRP), and heat shock protein 70 (HSP70) in patients with active Behçet’s uveitis.

Material/Methods

Forty patients with Behçet’s disease diagnosed according to the International Study Group criteria and 30 healthy individuals were included in the study. IL10, IL18, IFNG, IFNGR, CRP, and HSP70 gene expression levels were compared.

Results

Expression levels of IL18, IFNG, IFNGR, and CRP were significantly higher in patients with active Behçet’s uveitis than in control subjects (P<0.01 for all), whereas no significant differences were found in IL10 and HSP70 gene expression levels (P>0.01 for both).

Conclusions

IL18, IFNG, IFNGR, and CRP gene expression is significantly increased in active Behçet’s uveitis. There was no significant difference between active Behçet’s uveitis patients and controls in terms of IL10 and HSP70 gene expression levels. We conclude that drugs prescribed to Behçet’s patients with active uveitis downregulate gene expression.

Natural Killer Cell Subsets and Their Functional Activity in Behçet's Disease

BACKGROUND

Behçet's disease (BD) is a rare, chronic autoinflammatory disorder of unknown origin. Natural killer (NK) cells are one of the major immunoregulatory cell groups of the innate immune system, but their role in BD pathogenesis is not well documented.

OBJECTIVES

We aimed to investigate the role of NK cell subsets and their cytokine secretion and cytotoxic activity in patients with BD.

PATIENTS AND METHODS

The study group consisted of BD patients who had only mucocutaneous involvement, and they were compared with healthy subjects. BD patients were divided into two groups according to their frequencies of oral ulcerations. NK cell cytotoxicity was determined using CD107a expression and a CFSE-based cytotoxicity test. Expression of NK cell receptors and surface markers and the intracellular IL-5, IL-10, IL-17, and IFN-γ levels in CD16⁺ NK cells were assessed by flow cytometry.

RESULTS

Although the cytokine secretion pattern was different, no difference was obtained in cytotoxic activity, expression of activatory receptors, or degranulation of NK cells.

CONCLUSION

Increases in NK1/NK2 ratio and CD16⁺IFN-γ⁺ NK1 cells might support the idea of a biased IFN-γ dominant immune response in the mucocutaneous involvement of BD pathogenesis. Although the cytokine secretion pattern was different, no difference was obtained in cytotoxic activity, expression of activatory receptors, or degranulation of NK cells.

The immune dysfunction in ankylosing spondylitis patients

Ankylosing spondylitis (AS) is a spinal arthritic disease that is often associated with human leukocyte antigen (HLA)-B27, while only part of HLA-B27 carriers become AS patients. T cells have been reported to play an important role in the pathology of AS. T-cell immunoglobulin and mucin-domain-containing molecule 3 (Tim-3) and programmed death-1 (PD-1) have been known to negatively regulate the immune response. In this study, we used flow cytometry to analyze the immunological differences of peripheral bloodfrom 21 patients with AS, 22 cases who didn't have AS but were found to be HLA-B27 positive (HLA-B27+ group), and 16 normal healthy individuals (Healthy group). The level of CD4+, CD8+ T cells,and Treg of each group was observed. The expression of Tim-3 and PD-1 and the production of IFN-γ, IL-6, TNF-α, IL-4, and IL-10 were examined as well. We found that the percentage of Treg in AS group was lower than that of healthy group. The expression of PD-1 on CD8+ T cells and Tim-3 on CD4+ T cells was lower in the AS group. AS group had lower IL-10 production by CD4+ T cells and higher IL-6 production by CD8+ T cells. The results of HLA-B27+ group were similar to that of the healthy group. These data suggested that patients with AS had an impairment in the ability to negatively regulate the immune response, which might be related to the etiology of AS. To further investigate the roles of Tim-3 and PD-1 on is a dysfunction of T cells in AS that is associated with PD-1 and Tim-3.

Pharmacological Inactivation of Src Family Kinases Inhibits LPS-Induced TNF-α Production in PBMC of Patients with Behçet's Disease

Behçet's disease (BD) is a multisystemic chronic inflammatory disease characterized by relapsing oral and genital ulcers, uveitis, and skin lesions. The pathogenesis of BD is still unknown. Aberrant production of some cytokines/chemokines plays an important role in the pathogenesis of various inflammatory diseases. Revealing a key signaling regulatory mechanism involved in proinflammatory cytokines/chemokines production is critical for understanding of the pathogenesis of BD. The aim of this study was to determine the role of Src family kinases (SFKs) in production of some LPS-induced proinflammatory cytokines/chemokines in peripheral blood mononuclear cells (PBMC) of active BD patients. Chemical inhibition of SFKs activity impaired LPS-induced TNF-α production in PBMC of active BD patients, suggesting that modulating SFKs activity may be a potential target for BD treatment.

IL-2/IL-2 antibody immune complex regulates HSV-induced inflammation through induction of IL-2 receptor alpha, beta, and gamma in a mouse model

The differences of serum IL-2 levels were not consistent between Behçet's Disease (BD) patients and healthy controls, however, the correlation of interleukin-2 receptor (IL-2R) and BD has not been investigated. IL-2R is composed of three subunits; alpha, beta, and gamma. The expression frequencies of IL-2R subunits were analyzed in the peripheral blood mononuclear cells, spleens, and lymph node (LN) cells. The expression of IL-2R subunits was different between BD mice and controls. IL-2R beta expressing cell frequencies were also different between BD patients and healthy controls. The IL-2/anti-mIL-2 antibody complex administration regulated the IL-2R subunits in mice. The change of expression in IL-2R was accompanied by the increase of CD8+CD44+ memory T cells, CD3-NK1.1+CD11b+CD27+ natural killer cells, and improvement of symptoms. In this study, we elucidated the role of IL-2R subunits on BD, a finding that can be connected to therapeutic strategy for patients based on the results from the treatment of BD mice.

Annexin A2 as a target endothelial cell membrane autoantigen in Behçet's disease

Cell membrane proteins are believed to play a critical role in the pathogenesis of autoimmune diseases. However, few membrane autoantigens have been linked with Behçet's disease. Here, a cell-chip was performed to identify autoantibody target cells, and the suspected autoantigens were detected using immunoblotting. The amino acid sequences of the detected proteins were determined using LC-MALDI-TOF/TOF. Putative proteins were recombinantly expressed and purified, and a corresponding ELISA was developed and clinically validated using real clinical samples. It was found that a 36-kDa membrane protein--annexin A2--was detected in approximately one-third of the patients' blood circulation. The immunohistochemistry results showed that annexin A2 was highly expressed in vascular endothelial cells. Moreover, vascular involvement was significantly higher in the anti-annexin A2 antibody-positive group versus the anti-annexin A2 antibody-negative group among all the clinical samples analyzed, indicating that annexin A2 is a novel endothelial cell membrane antigen involved in Behçet's disease.

IL-22-secreting Th22 and IFN-γ-secreting Th17 cells in Behçet's disease

OBJECTIVE

Behçet's disease (BD) is a systemic inflammatory disease with unknown etiology. Studies have shown that some T helper (Th) 1-associated cytokines have role in the inflammation of BD. The CD4(+) Th cells can be differentiated into Th1, Th2, Th17 and Th22 secrete different cytokines to regulate immune system. In this study, cytokine secretion of Th subsets in BD was investigated.

METHODS

The study group consisted of 26 BD patients with mucocutaneous involvement and 12 healthy subjects. Lymphocyte subpopulations, IL-5, IL-10, IL-17, IL-22 and IFN-γ secretion of CD4(+) T and Foxp3(+) Treg cells were determined by flow cytometry.

RESULTS

Compared with healthy subjects, Th1 (IL-17A(-)IL-22(-)IFN-γ(+)), Th22 (IL-17A(-)IL-22(+)IFN-γ) and IL-17A(+)IFN-γ(+)-secreting cells were significantly increased, and the percentage of Treg cells were dramatically reduced in BD patients. The frequency of recurrent oral ulcers was associated with increased Th22 cells.

CONCLUSIONS

Our study describes an association between Th22 cell subset and IL-17A(+) IFNγ(+)-secreting cells with mucocutaneous BD. These findings revealed that reduced levels of Tregs and increased levels of Th1 and Th22 cells as well as Th17/Th1 cells might be associated with the pathogenesis of BD.