Relationship of CTLA4 and CD28 polymorphisms with lung involvement, HRCT findings and pulmonary function tests in Turkish patients with ankylosing spondylitis

What do we know about co-stimulatory and co-inhibitory immune checkpoint signals in ankylosing spondylitis?

Ankylosing spondylitis is the main entity of a family of inflammatory diseases affecting many musculoskeletal (sacroiliac joints, spine, and peripheral joints) and extra-musculoskeletal sites, termed spondyloarthritis. While it is debated whether disease onset is primarily driven by autoimmune or autoinflammatory processes, what is certain is that both innate and adaptive immune responses orchestrate local and systemic inflammation, which leads to chronic pain and immobility. Immune checkpoint signals are one key player in keeping the immune system in check and in balance, but their role in disease pathogenesis is still rather elusive. Therefore, we ran a MEDLINE search utilizing the PubMed platform for a variety of immune checkpoint signals in regard to ankylosing spondylitis. In this review, we summarize the experimental and genetic data available and evaluate the relevance of immune checkpoint signalling in the pathogenesis of ankylosing spondylitis. Markers such as PD-1 and CTLA-4 have been extensively studied and facilitate the concept of an impaired negative immune regulation in ankylosing spondylitis. Other markers are either neglected completely or insufficiently examined, and the data is conflicting. Still, some of those markers remain interesting targets to decipher the pathogenesis of ankylosing spondylitis and to develop new treatment strategies.

Value of HRCT of the chest in evaluation of ankylosing spondylitis: correlation between pleuro-parenchymal abnormalities and disease activity

Background

Ankylosing spondylitis (AS) is a chronic inflammatory disorder primarily involving the sacroiliac joints and spine. It is associated with both articular and extra-articular clinical manifestations. Pulmonary involvement is a well-recognized comorbidity of AS, even among patients with early disease. The availability of high-resolution computed tomography (HRCT) has enabled better visualization of the entire lung parenchyma and earlier identification of lung pathologies, ranging from mild to more severe involvement, which were previously missed on X-rays. The aim of the study is to establish the role of HRCT in the detection of pleuro-parenchymal manifestations of AS and to look for correlations between these findings and AS activity.

Results

Lung CT scans were done for all our patients and 27 patients (90%) had positive HRCT thoracic findings, while the remaining 3 patients (10%) had a normal HRCT thoracic study. Lower lobe fibrotic changes were the most common finding seen in 20 patients (66.7%) followed by bronchial wall thickening in 13 patients (43.3%) and upper and lower fibrotic changes seen in 9 patients (30%). HRCT thoracic findings were more prominent in late AS (disease duration ≥ 10 years) (13 of 13 patients); while 14 of 17 patients with early AS (disease duration < 10 years) had mildly abnormal HRCT findings. The result of statistical analysis showed that there was negative correlation between thoracic findings and disease activity assessed by BASDAI and this correlation was insignificant (p value = 0.5).

Conclusion

HRCT offers an accurate and safe method of assessment of lung disease in patients with AS and without respiratory symptoms. Although there was no correlation between pulmonary findings and AS activity assessed by BASDAI, a positive correlation, albeit insignificant, between pulmonary involvement and disease duration had been found.

Differential gene expression analysis of ankylosing spondylitis shows deregulation of the HLA-DRB, HLA-DQB, ITM2A, and CTLA4 genes

Background

Ankylosing spondylitis (AS) is a rare inflammatory disorder affecting the spinal joints. Although we know some of the genetic factors that are associated with the disease, the molecular basis of this illness has not yet been fully elucidated, and the genes involved in AS pathogenesis have not been entirely identified. The current study aimed at constructing a gene network that may serve as an AS gene signature and biomarker, both of which will help in disease diagnosis and the identification of therapeutic targets. Previously published gene expression profiles of 16 AS patients and 16 gender- and age-matched controls that were profiled on the Illumina HumanHT-12 V3.0 Expression BeadChip platform were mined. Patients were Portuguese, 21 to 64 years old, were diagnosed based on the modified New York criteria, and had Bath Ankylosing Spondylitis Disease Activity Index scores > 4 and Bath Ankylosing Spondylitis Functional Index scores > 4. All patients were receiving only NSAIDs and/or sulphasalazine. Functional enrichment and pathway analysis were performed to create an interaction network of differentially expressed genes.

Results

ITM2A, ICOS, VSIG10L, CD59, TRAC, and CTLA-4 were among the significantly differentially expressed genes in AS, but the most significantly downregulated genes were the HLA-DRB6, HLA-DRB5, HLA-DRB4, HLA-DRB3, HLA-DRB1, HLA-DQB1, ITM2A, and CTLA-4 genes. The genes in this study were mostly associated with the regulation of the immune system processes, parts of cell membrane, and signaling related to T cell receptor and antigen receptor, in addition to some overlaps related to the IL2 STAT signaling, as well as the androgen response. The most significantly over-represented pathways in the data set were associated with the “RUNX1 and FOXP3 which control the development of regulatory T lymphocytes (Tregs)” and the “GABA receptor activation” pathways.

Conclusions

Comprehensive gene analysis of differentially expressed genes in AS reveals a significant gene network that is involved in a multitude of important immune and inflammatory pathways. These pathways and networks might serve as biomarkers for AS and can potentially help in diagnosing the disease and identifying future targets for treatment.

Association of CTLA-4 (+49 A/G) polymorphism with susceptibility to autoimmune diseases: A meta-analysis with trial sequential analysis

OBJECTIVES

In recent years, more and more studies have been focusing on the association between Cytotoxic T lymphocyte antigen-4 (CTLA-4) (+49 A/G) gene polymorphism and autoimmune diseases. However, the results of previous studies are still controversial. The meta-analysis is aiming at determining the association in CTLA-4 (+49 A/G) gene rs231775 polymorphism and ankylosing spondylitis (AS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE).

METHODS

We searched PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Chinese Biomedical Database (CBM) up to November 2020, use random or fixed-effect models to perform meta-analysis to compare alleles and other genetic models, including homozygous, heterozygous, recessive and dominant models. The odds ratio (OR) with a 95% confidence interval (95% CI) was used to assess the correlation between CTLA-4 (+49 A/G) gene polymorphism and the genetic affectability of AS, RA, and SLE. Meanwhile, we used sequential trial analysis (TSA) to analyze the reliability of the results. Finally, we searched the relevant data of genome-wide association studies (GWAS) to further verify the accuracy of the experimental results.

RESULTS

47 studies with 11,893 cases and 12,032 healthy controls were included. The rs231775 G allele was relevant to high risk of autoimmune disease over all people (P < 0.05). The G allele of rs231775 was significantly related to RA susceptibility (P < 0.05), but not with AS or SLE. Subgroup analysis by ethnicity indicated that rs231775 G allele was closely related to RA in Caucasian populations and Mongolian populations (P < 0.05). A strong connection within rs231775 G allele and AS affectability was uncovered in Caucasian populations (P < 0.05). The analysis of the TSA shows that the meta-analysis can draw the conclusion.

CONCLUSION

CTLA-4 (+49 A/G) gene rs231775 G allele increases the risk of autoimmune diseases in Caucasian populations. And it also increases the risk of RA in Caucasian and Mongolian populations. More sample size and more elaborately designed studies are needed to elucidate the relationship in CTLA-4 (+49 A/G) gene rs231775 G allele and autoimmune diseases, especially AS, SLE.

Rapidly Progressive Pulmonary Apical Fibrosis and Parenchymal Destruction in a Patient with Ankylosing Spondylitis

Pulmonary apical fibrosis is a rare complication of ankylosing spondylitis (AS). The essential characteristics of this lesion are its very slow progression and frequently asymptomatic nature. Herein, we are presenting a patient with AS who rapidly developed pulmonary apical fibrosis in a 3-year period despite decreased musculoskeletal pains. The 60-year-old male applied with complaints of progressively increasing cough in the recent two years, dyspnea, and fatigue. He had no chronic disease except AS. He had no continuous medication except nonsteroid anti-inflammatory drugs for 2-3 days monthly since his musculoskeletal pains decreased in the recent years. His physical examination revealed reduced breath sounds in the upper zones of the right lung. Chest X-ray revealed increased diffuse opacity in the upper zones of the right lung. Thoracic high-resolution computed tomography showed a consolidation accompanied with traction bronchiectases compatible with chronic fibrosis in the upper lobe of the right lung. However, thoracic computed tomography of the patient performed 3 years ago did not reveal pulmonary apical fibrosis and parenchymal destruction. Biopsy revealed no finding of malignancy, granulomatous inflammation, or vasculitis. The results of cultures were negative. So, the patient was diagnosed as pulmonary involvement of AS, which developed in a 3-year period. This case has shown that extra-articular complications may continue to develop in patients with AS even if their musculoskeletal complaints have subsided. So, patients with AS should be followed up regularly with systemic examinations.