The pathogenesis of ankylosing spondylitis

Immune-mediated lung diseases: A narrative review

The role of immunity in the pathogenesis of various pulmonary diseases, particularly interstitial lung diseases (ILDs), is being increasingly appreciated as mechanistic discoveries advance our knowledge in the field. Immune-mediated lung diseases demonstrate clinical and immunological heterogeneity and can be etiologically categorized into connective tissue disease (CTD)-associated, exposure-related, idiopathic, and other miscellaneous lung diseases including sarcoidosis, and post-lung transplant ILD. The immunopathogenesis of many of these diseases remains poorly defined and possibly involves either immune dysregulation, abnormal healing, chronic inflammation, or a combination of these, often in a background of genetic susceptibility. The heterogeneity and complex immunopathogenesis of ILDs complicate management, and thus a collaborative treatment team should work toward an individualized approach to address the unique needs of each patient. Current management of immune-mediated lung diseases is challenging; the choice of therapy is etiology-driven and includes corticosteroids, immunomodulatory drugs such as methotrexate, cyclophosphamide and mycophenolate mofetil, rituximab, or other measures such as discontinuation or avoidance of the inciting agent in exposure-related ILDs. Antifibrotic therapy is approved for some of the ILDs (e.g., idiopathic pulmonary fibrosis) and is being investigated for many others and has shown promising preliminary results. A dire need for advances in the management of immune-mediated lung disease persists in the absence of standardized management guidelines.

Ultrasonography of heel entheses in axial spondyloarthritis patients: frequency and assessment of associated factors

PURPOSE

Foot entheses involvement is a common manifestation of spondyloarthritis. The superiority of ultrasonography examination in foot entheses damages detection has been reported. We aimed to compare the ultrasonography findings of foot entheses between spondyloarthritis patients. and healthy controls and to identify factors associated with enthesitic heel involvement.

METHODS

We conducted a cross-sectional study including 37 patients with axial spondyloarthritis (G1) and 37 healthy subjects matched by age and gender (G0). The following pro-inflammatory cytokines were measured: Interleukin (IL-)1, IL-6, IL-17, and IL-23. A blind ultrasonography of foot entheses was performed to examine calcaneal tendon (CT) and plantar fascia (PF).

RESULTS

The mean age was 44.62 ± 12.31 years. Non-steroidal anti-inflammatory drugs were taken in 92% of patients. Clinical heel enthesopathy was noted in 10 patients (27%) of G1. No participant has enthesitic pain in G0. Ultrasonography changes in CT and PF were more frequent in G1 than G0 (p = 0.001 and p = 10-3, respectively). In the PF, tendon thickening was significantly higher in G1 than G0 (p = 0.03). Power Doppler in both enthesitic sites was exclusively observed in G1 (p = 10-3). Regarding associated factors, CT enthesophytes were less frequent in patients taking non-steroidal anti-inflammatory drugs continuously or having regular physical activity. PF structural damages were associated with higher erythrocyte sedimentation rate (p = 0.02), higher IL-23 level (p = 0.01), and higher disease activity (p = 0.04).

CONCLUSION

Ultrasonography lesions of heel entheses were frequent in spondyloarthritis. Disease activity and inflammatory markers were higher in patients with heel enthesitis. Non-steroidal anti-inflammatory drugs intake and regular physical activity may prevent enthesophytes' occurrence.

Identification of immune related cells and crucial genes in the peripheral blood of ankylosing spondylitis by integrated bioinformatics analysis

Background

Ankylosing spondylitis (AS) is a progressive rheumatic disease and studies reveal that the immune system is critical for the pathogenesis of AS. In the present study, various bioinformatics analysis methods were comprehensively applied, designed to identify potential key genes and inflammation states of AS.

Methods

The transcriptome profiles of GSE25101 and GSE73754 obtained from the Gene Expression Omnibus (GEO) database were merged for subsequent analyses. The differentially expressed genes (DEGs) were identified using the Bioconductor package Limma and threshold values. Functional enrichment and pathway enrichment analyses were performed using the clusterProfiler package and Gene Set Enrichment Analysis (GSEA). Next, protein-protein interaction (PPI) network of the identified DEGs was constructed by the online database, the Search Tool for the Retrieval of Interacting Genes (STRING), visualization and analysis were performed through Cytoscape software. Subsequently, we applied CIBERSORT algorithm to identify subpopulation proportions of immune cells in peripheral blood samples. Finally, we validated the hub genes with the GSE18781 dataset. Samples were collected from patients to validate gene and protein expression using qRT-PCR and ELISA.

Results

A total of 334 DEGs were identified, including 182 upregulated and 152 downregulated DEGs, between AS patients and normal human controls, which were primarily involved in immune response, autophagy, and natural killer cell-mediated cytotoxicity. The most prominent module and candidate biomarkers were identified from the PPI network. Biomarkers were selected for validation and their expressions were significantly decreased in peripheral blood samples which was consistent with transcriptome sequencing results. Nine genes with AUC > 0.70 were considered to be AS hub genes for ROC curve analysis, including GZMA, GZMK, PRF1, GNLY, NKG7, KLRB1, KLRD1, IL2RB and CD247. Furthermore, CIBERSORT results suggest that AS contained a higher proportion of CD8+ T cells, naive CD4+ T cells, neutrophils, and lower levels of gamma delta T cells compared with the normal controls.

Conclusion

In this study, we identified DEGs combined with their closely related biological functions and propose that granule-associated proteins and immune infiltration maybe involved in the progression of ankylosing spondylitis. These validated hub genes may provide new perspectives for understanding the molecular mechanisms of ankylosing spondylitis.

Serum Interleukin-23/17 Levels in Ankylosing Spondylitis Patients Treated with Nonsteroidal Anti-Inflammatory Drugs: A Prospective Cohort Study

Etiopathogenesis of ankylosing spondylitis (AS), a major subtype of a group of chronic inflammatory diseases known as spondyloarthropathies, is not clearly understood yet. In this study, we aimed to investigate the interleukin 23 (IL-23)/interleukin-17 (IL-17) pathway, which is a new cytokine pathway in inflammatory diseases. We evaluated serum IL-17 and IL-23 levels after 1-year follow-up in AS patients using only nonsteroidal anti inflammatory drugs (at need or continue). Forty-four AS patients and 40 healthy controls were included in the study. Clinical evaluations of disease activity were performed. Serum tumor necrosis factor-α (TNF-α), IL-6, IL-17, and IL-23 levels were evaluated. IL-17 and IL-23 levels of the patient group at baseline and 12 months were lower than the control group. There was no significant difference between the baseline and 12th month evaluations of the patient group. TNF-α levels were similar in all groups (in the baseline and 12th month of the patient group and in the control group). Although our results are in contrast to the literature findings, the IL-23/IL-17 pathway is a newly discovered pathway, and there may still be unknowns. New studies involving larger patient groups are needed for the factors affecting serum IL-23/IL-17 levels in patients with AS. We also think that it will be useful to make more comprehensive and long-term studies about which patients will respond well to IL-23/IL-17 blockade.

Optimization of an in-house PCR method for the detection of HLA-B*27 alleles

The association of spondyloarthropathies with different alleles of human leukocyte antigen (HLA) B*27 is well established. Different subtypes of HLA-B*27 may be linked with different ethnic groups, distinct clinical manifestations, specific age of onset and different prognoses. Polymerase chain reaction with sequence specific primers (PCR-SSP) is the most frequently adapted molecular method used for the recognition of HLA-B*27-specific DNA sequences. The aim of the present study was to standarise an in-house protocol of PCR-SSP for HLA-B*27 allele detection for use in the Armed Forces Institute of Pathology (AFIP), Pakistan, with consideration of its cost effectiveness. A total of 49 individual samples were included, comprising 10 transplant samples determined to be HLA-B*27-negative by PCR-SSP and 39 HLA-B*27-positive samples determined by flow cytometry, obtained from patients who were symptomatic and referred for HLA-B*27 testing. By altering each variable individually, an in-house PCR-SSP protocol was optimized to amplify common HLA-B*27 alleles (2701-2721, 2723-2730). To discriminate B*27 from all other HLA-B alleles, a low-resolution HLA-B typing set with a 96 PCR-SSP primer mixture was used in conjunction. Among the 39 HLA-B*27-positive specimens, 31 (79%) were detected as positive by PCR-SSP, with the remaining samples failing due to a sub-optimized protocol and/or low DNA concentration. Additionally, there was complete concordance between flow cytometry and in-house PCR, and the sensitivity and specificity of the PCR-SSP were determined to be 100%. In conclusion, in-house SSP-PCR is, standard method for the detection of HLA-B*27 alleles. The determination of associations between specific HLA-B*27 alleles and AS may aid to identify individuals at higher risk of developing the disease. Furthermore, the identification of individuals at risk may aid to adapt preventive strategies.

Plasma levels of pentraxin 3 in patients with spondyloarthritis

CONTEXT

Determining the disease's inflammatory activity in spondyloarthritis (SpA) is difficult although very important as it is this that drives treatment.

OBJECTIVE

To investigate if plasma pentraxin-3 (PTX3) could act as an inflammatory marker in SpA.

METHODS

Eighty one SpA patients (11 with psoriatic arthritis (PsoA) and 70 with ankylosing spondylitis (AS)) and 90 gender and age paired controls were studied for plasma PTX3 levels by ELISA. Patients had determinations of disease activity through C reactive protein (CRP), erythrocyte sedimentation rate (ESR), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP. Epidemiological, clinical and treatment data were collected through chart review.

RESULTS

SpA patients had lower concentrations of plasma PTX3 than controls (median of 0.95 ng/mL vs 1.64 ng/mL; p < 0.0001). Correlation of PTX3 levels and BASDAI, ASDAS-CPR, CRP levels and ESR could not be found. No differences in PTX3 levels were detected between PSoA and AS patients (p = 0.42). Uveitis, presence of HLA B27, tobacco exposure, age and disease duration did not influence PTX3 levels.

CONCLUSIONS

PTX3 plasma levels do not reflect disease activity in SpA. However, it probably participates in the ethiopathogenetic process, as it is consumed in these patients.

Serum HMGB1 Serves as a Novel Laboratory Indicator Reflecting Disease Activity and Treatment Response in Ankylosing Spondylitis Patients

Objective. High mobility group box 1 (HMGB1) is a late inflammatory factor participating in the pathogenesis of various autoimmune and inflammatory diseases. In the current study, we analyzed the association between serum levels of HMGB1 and clinical features of AS patients before and during treatment. Methods. Serum HMGB1 was detected in 147 AS patients and 61 healthy controls using ELISA. We evaluated the association between HMGB1 and extra-articular manifestations as well as disease severity indices. Among these AS patients, 41 patients received close follow-up at 1, 3, and 6 months after treatment. This group comprised 25 patients treated with anti-TNF-α biologics and 16 patients receiving oral NSAIDs plus sulfasalazine. Results. The serum HMGB1 of AS patients was significantly higher than in healthy controls and positively correlated with BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, ESR, and CRP, but not with HLA-B27, anterior uveitis, and recurrent diarrhea. There was no significant difference between patients with radiographic damage of hip joints and those without. We observed that serum HMGB1 paralleled disease activity after treatment. Conclusion. Serum level of HMGB1 is higher in AS patients, and to some extent, HMGB1 can reflect the activity of AS and be used as a laboratory indicator to reflect the therapeutic response.

Elevated Serum Levels of Soluble CD30 in Ankylosing Spondylitis Patients and Its Association with Disease Severity-Related Parameters

Soluble CD30 (sCD30), a transmembrane glycoprotein that belongs to the tumor necrosis factor receptor (TNFR) superfamily, has been shown to be associated with various pathological conditions. This study was designed to measure the levels of serum sCD30 in patients with ankylosing spondylitis (AS) and to evaluate the relationships between serum sCD30 levels and other disease severity-related indexes, including bath ankylosing spondylitis disease activity index (BASDAI), ankylosing spondylitis disease activity score (ASDAS), and bath ankylosing spondylitis functional index (BASFI). Our results demonstrated significantly elevated sCD30 levels in AS patients compared to healthy controls (HCs) with mean values of 32.0 ± 12.2 and 24.9 ± 8.0 ng/mL, respectively (P^** = 0.007), suggesting a potential role of sCD30 in the pathogenesis of AS. However, no significant correlations of sCD30 with BASDAI, ASDAS, or BASFI were detected in our study (P > 0.05). Therefore, sCD30 cannot be used as a reliable marker for reflecting disease activity and functional ability of AS patients.

Association between KIR polymorphisms and ankylosing spondylitis in populations: a meta-analysis

OBJECTIVES

Published association studies of killer cell immunoglobulin-like receptors (KIRs) and ankylosing spondylitis (AS) in populations are inconsistent. The aim of this study is to determine whether the KIR polymorphisms confer susceptibility to AS in populations by conducting a meta-analysis.

METHODS

A computer search was carried out up to August 2013 for literature pertaining to AS and KIR polymorphisms. Publications addressing the association between the KIR polymorphisms and susceptibility to AS in populations were selected from the Pubmed, Elsevier Science Direct, China National Knowledge Infrastructure (CNKI) and Chinese Biomedical Literature Database (CBM) databases. The odds ratio (OR) with 95% confidence interval (95%CI) was calculated.

RESULTS

A total of 13 case-control studies in 9 articles were included in this meta-analysis. Meta-analysis results identified two positive associations of 2DS4 and 3DS1 with susceptibility to AS in populations. In subgroup analysis, there was a positive association between 2DS4 and susceptibility to AS in Asians, but not in Caucasians. And there were associations between 3DL1, 3DS1 and susceptibility to AS in Caucasians, but not in Asians. Results of subgroup analysis also showed that there were associations between 2DL5, 2DS4, 2DS5, 3DL1, 3DS1 and susceptibility to AS in HLA-B*27-positive patients and HLA-B*27-positive healthy controls.

CONCLUSIONS

This meta-analysis confirms that 2DS4 and 3DS1 might be potential risk factors for AS in populations.

Bisphosphonates: focus on inflammation and bone loss

Bisphosphonates are pharmacological compounds that have been used for the prevention and treatment of several pathological conditions including osteoporosis, primary hyperparathyroidism, osteogenesis imperfecta, and other conditions characterized by bone fragility. Many studies have been performed to date to analyze their effects on inflammation and bone remodelling and related pathologies. The aim of this review is, starting from a background on inflammatory processes and bone remodelling, to give an update on the use of bisphosphonates, outlining the possible side effects and proposing new trends for the future. Starting from a brief introduction on inflammation and bone remodelling, we collect and analyze studies involving the use of bisphosphonates for treatment of inflammatory conditions and pathologies characterized by bone loss. Selected articles, including reviews, published between 1976 and 2011, were chosen from Pubmed/Medline on the basis of their content. Bisphosphonates exert a selective activity on inflammation and bone remodelling and related pathologies, which are characterized by an excess in bone resorption. They improve not only skeletal defects, but also general symptoms. Bisphosphonates have found clinical application preventing and treating osteoporosis, osteitis deformans (Paget's disease of bone), bone metastasis (with or without hypercalcaemia), multiple myeloma, primary hyperparathyroidism, osteogenesis imperfecta, and other conditions that feature bone fragility. Further clinical studies involving larger cohorts are needed to optimize the dosage and length of therapy for each of these agents in each clinical field in order to be able to maximize their properties concerning modulation of inflammation and bone remodelling. In the near future, although "old" bisphosphonates will reach the end of their patent life, "new" bisphosphonates will be designed to specifically target a pathological condition.

Infectious, inflammatory, and metabolic diseases affecting the athlete's spine

Sports and weight-bearing activities can have a positive effect on bone health in the growing, mature, or aging athlete. However, certain athletic activities and training regimens may place the athlete at increased risk for stress fractures in the spine. In addition, some athletes have an underlying susceptibility to fracture due to either systemic or focal abnormalities. It is important to identify and treat these athletes in order to prevent stress fractures and reduce the risk of osteoporosis in late adulthood. Therefore, the pre-participation physical examination offers a unique opportunity to screen athletes for metabolic bone disease through the history and physical examination. Positive findings warrant a thorough workup including a metabolic bone laboratory panel, and possibly a DEXA scan, which includes a lateral spine view.

Polymorphisms of KIR gene and HLA-C alleles: possible association with susceptibility to HLA-B27-positive patients with ankylosing spondylitis

Accumulating evidences indicate that killer cell immunoglobulin-like receptors (KIRs) and their corresponding specific HLA-C ligands contribute to the pathogenesis of multiple autoimmune diseases via the modulation of natural killer (NK) cell and T cell functions. The present study was performed to investigate whether the polymorphism of KIR genes and HLA ligands associates with the susceptibility of ankylosing spondylitis (AS). Previous studies have demonstrated a strong association between HLA-B27 gene and the pathogenesis of AS. In this study, 115 unrelated HLA-B27-positive AS patients and 119 HLA-B27-positive healthy controls were recruited. Polymerase chain reaction using sequence-specific primers was used to determine the genotypes of KIR genes and HLA-C alleles. The results showed that the frequencies of KIR2DL1 and KIR2DL5 were significantly higher in the AS patient group than those in the control group (p = 0.012 and p = 0.009, respectively). Meanwhile, individuals with AS showed an increased frequency of HLA-Cw*08 (p = 0.001, p (c)  = 0.008) compared with that in controls. Our findings indicate that with the genetic background of HLA-B27, variation at the KIRs and their corresponding specific HLA-C ligands may influence the ability of NK cells and T cells to recognize and lyse targets in immune responses, which thereby contributes to pathogenesis of AS.