Changes in gene expression profiles of the hip joint ligament of patients with ankylosing spondylitis revealed by DNA chip

Sacroiliac joint fusion in patients with ankylosing spondylitis is associated with hip involvement

OBJECTIVE

Ankylosing spondylitis (AS) is a progressive inflammatory disease that affects the axial skeleton, and often associated with hip involvement. However, the causative factors for radiological hip involvement in patients with AS are not well characterized. This study aimed to investigate the factors associated with hip involvement in patients with AS.

METHODS

Sixty-seven patients (134 hips) diagnosed with AS who qualified the modified New York criteria at our institution between January 2005 and June 2022 were enrolled. Patients were divided into two groups: the hip involvement group (BASRI-hip score ≥2 points) and the normal group (BASRI-hip score <2 points). Demographic, clinical and radiographic characteristics were compared between the two groups.

RESULTS

Twenty-six patients (38.8%) had radiological hip involvement, of which 23 (88.5%) patients were male. There were significant between-group differences with respect to sacroiliac joint fusion, crossover sign, high centre edge angle and low sharp angle (P < 0.05). On logistic regression analysis, older age, sacroiliac joint fusion and pincer type were identified as independent risk factors for hip involvement.

CONCLUSION

AS with hip involvement was significantly more likely to involve sacroiliac joint fusion, which suggested that mechanical stress in adjacent joints and reduced spinopelvic range of motion may influence hip involvement.

Age and Symptoms at Onset of Ankylosing Spondylitis in Japanese Patients

OBJECTIVE

To examine the age at onset and initial symptoms as clinical features of ankylosing spondylitis (AS) in Japanese patients.

METHODS

This retrospective study included 60 Japanese patients diagnosed with AS at our institute between January 2004 and June 2021. Initial symptoms were considered pain in axial joints and/or extra-axial joints. If a patient had initial symptoms at multiple sites, each site was counted. We assessed trends for the number of patients and sites of initial symptoms according to age at onset.

RESULTS

Mean age (± standard deviation) at onset was 28.9 (± 14.3) years. Approximately one-third of patients experienced onset before age 20. The back was the most common site of initial symptoms (36.7%), followed by the hip (26.7%), knee (15%), buttocks (15%), neck (10%), finger (6.7%), shoulder (3.3%), and others (including overlapping sites). Thirty-two (53.3%) and 25 (41.7%) patients had initial symptom only in axial joints and only in extra-axial joints, respectively. The proportion of patients with initial symptoms only in extra-axial joints significantly decreased with increasing age (p=0.024).

CONCLUSION

Sites of initial symptoms were frequently the back, hip, knee, and buttocks, and 41.7% had initial symptom only in extra-axial joints. Younger onset patients frequently had extra-axial involvement.

Novel approaches to develop biomarkers predicting treatment responses to TNF-blockers

Introduction: Chronic inflammatory diseases (CIDs) cause significant morbidity and are a considerable burden for the patients in terms of pain, impaired function, and diminished quality of life. Important progress in CID treatment has been obtained with biological therapies, such as tumor-necrosis-factor blockers. However, more than a third of the patients fail to respond to these inhibitors and are exposed to the side effects of treatment, without the benefits. Therefore, there is a strong interest in developing tools to predict response of patients to biologics. Areas covered: The authors searched PubMed for recent studies on biomarkers for disease assessment and prediction of therapeutic responses, focusing on the effect of TNF blockers on immune responses in spondyloarthritis (SpA), and other CID, in particular rheumatoid arthritis and inflammatory bowel disease. Conclusions will be drawn about the possible development of predictive biomarkers for response to treatment. Expert opinion: No validated biomarker is currently available to predict treatment response in CID. New insight could be generated through the development of new bioinformatic modeling approaches to combine multidimensional biomarkers that explain the different genetic, immunological and environmental determinants of therapeutic responses.

Genetics and Functional Genomics of Spondyloarthritis

Spondyloarthritis (SpA) is a chronic inflammatory disorder with high heritability but with complex genetics. It encompasses several entities that share common clinical features. Most of the genetic studies in SpA have been restricted to ankylosing spondylitis (AS), the prototypical form of SpA. However, there is growing evidence of shared genetic background between all the SpA subtypes and also with some other immune-mediated diseases. The most important part of SpA heritability comes from the HLA-B27 allele in the major histocompatibility complex (MHC) that explains around 25% of the attributable heredity. Several other loci outside of the MHC have been shown to be involved in the disease. However, all these non-MHC loci explain only a small additional fraction of disease predisposition. Thus, a substantial fraction of SpA genetic basis remains poorly understood. Gene expression profiling is a complementary approach to elucidate the underlying mechanisms and pathways that drive the disease. Several expression profiling studies have been undertaken in SpA. However, results have been quite disappointing with little overlap between the studies largely due to the small sample sizes, resulting in limited power to discover small effects. In this review, we summarize current knowledge on genetic findings concerning SpA and we describe strategic approaches for identification of additional variants, with a focus on rare variants in familial forms. We also provide an overview of gene expression studies in SpA and discuss the possibilities offered by high-throughput RNA sequencing technologies, in particular in sorted cells. Finally, issues in establishing molecular mechanisms underlying genetic association hits and potential translational applications will be addressed.

Expression and Metabolomic Profiling in Axial Spondyloarthritis

PURPOSE OF REVIEW

The purpose of this review is to highlight recent evidence with respect to expression and metabolomic profiling in axial spondyloarthritis (axSpA) that included ankylosing spondylitis (AS).

RECENT FINDINGS

AxSpA is not only characterized by the strongest genetic contribution for any complex rheumatic disease but is also influenced by environmental and immunological factors. Large-scale association-based studies have identified over 100 genetic variants contributing to 30% of the genetic risk of ankylosing spondylitis. Recent studies in global expression and metabolomic profiling appear to highlight common themes despite differences in tissues, populations, techniques, and relative paucity of patients in many of these studies. Expression studies support a role for immunomodulation and bone remodeling in the pathogenesis and progression of axSpA/AS, while metabolomic studies implicate the importance of the intestinal microbial metabolism as well as fat and choline metabolic pathways in AS.

Dissecting the Underlying Pharmaceutical Mechanism of Chinese Traditional Medicine Yun-Pi-Yi-Shen-Tong-Du-Tang Acting on Ankylosing Spondylitis through Systems Biology Approaches

Traditional Chinese Medicine (TCM) has been served as complementary medicine for Ankylosing Spondylitis (AS) treatment for a long time. Yun-Pi-Yi-Shen-Tong-Du-Tang (Y-Y-T) is a novel empirical formula designed by Prof. Chengping Wen. In this study, a retrospective investigation supported efficacy of Y-Y-T and then we deciphered the underlying molecular mechanism of the efficacy. Herbal ingredients and targeting proteins were collected from TCMID. PPI networks were constructed to further infer the relationship among Y-Y-T, drugs used for treating AS, differentially expressed genes of AS patients and AS disease proteins. Finally, it was suggested that TLR signaling pathway and T cell receptor signaling pathway may involve in the biological processes of AS progression and contribute to the curative effect and proteins such as JAK2, STAT3, HSP90AA1, TNF and PTEN were the key targets. Our systemic investigation to infer therapeutic mechanism of Y-Y-T for AS treatment provides a new insight in understanding TCM pharmacology.

Transcriptome analysis of ankylosing spondylitis patients before and after TNF-α inhibitor therapy reveals the pathways affected

Tumor necrosis factor-α (TNF-α) inhibitors are highly effective in suppressing inflammation in ankylosing spondylitis (AS) patients, and operate by suppression of TFN-α and downstream immunological pathways. To determine the mechanisms of action of TNF-α inhibitors in AS patients, we used transcriptomic and bioinformatic approaches on peripheral blood mononuclear cells from AS patients pre and post treatment. We found 656 differentially expressed genes, including the genome-wide significant AS-associated genes, IL6R, NOTCH1, IL10, CXCR2 and TNFRSF1A. A distinctive gene expression profile was found between male and female patients, mainly because of sex chromosome-linked genes and interleukin 17 receptor C, potentially accounting for the differences in clinical manifestation and treatment response between the genders. In addition to immune and inflammation regulatory pathways, like intestinal immune network for IgA production, cytokine-cytokine receptor interaction, Ras signaling pathway, allograft rejection and hematopoietic cell lineage, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses revealed that infection-associated pathways (influenza A and toxoplasmosis) and metabolism-associated pathways were involved in response to TNF-α inhibitor treatment, providing insight into the mechanism of TNF-α inhibitors.

Ankylosing spondylitis: beyond genome-wide association studies

PURPOSE OF REVIEW

This article discusses genomic investigations in ankylosing spondylitis (AS) beyond genome-wide association (GWA) studies, but prior to this, genetic variants achieving genome-wide significance will be summarized highlighting key pathways contributing to disease pathogenesis.

RECENT FINDINGS

Evidence suggests that disease pathogenesis is attributed to a complex interplay of genetic, environmental and immunological factors. GWA studies have greatly enhanced our understanding of AS pathogenesis by illuminating distinct immunomodulatory pathways affecting innate and acquired immunity, most notably the interleukin-23/interleukin-17 pathway. However, despite the wealth of new information gleaned from such studies, a fraction of the heritability (24.4%) has been explained. This review will focus on investigations beyond GWA studies including copy number variants, gene expression profiling, including microRNA (miRNA), epigenetics, rare variants and gene-gene interactions.

SUMMARY

To address the 'missing heritability' and advance beyond GWA studies, a concerted effort involving rethinking of study design and implementation of newer technologies will be required. The coming of age of next-generation sequencing and advancements in epigenetic and miRNA technologies, combined with familial-focused investigations using well-characterized cohorts, is likely to reveal some of the hidden genomic mysteries associated with AS.

A Literature Review of Total Hip Arthroplasty in Patients with Ankylosing Spondylitis: Perioperative Considerations and Outcome

Ankylosing spondylitis is a spondyloarthropathy affecting the sacro-iliac joints with subsequent progression to the spine and the hip joints. The hip joints are affected by synovitis, enthesial inflammation, involvement of medullary bone, progressive degeneration and secondary osteoarthritis. Clinical presentation is usually in the form of pain and stiffness progressing to disabling fixed flexion contractures and in some instances, complete ankylosis. Hip arthroplasty should be considered for hip pain, postural and functional disability, or pain in adjacent joints due to hip stiffness. We conducted a literature review to determine peri-operative considerations and outcome in ankylosing spondylitis patients undergoing hip arthroplasty. In this review, we have discussed pre-operative surgical planning, thromboprophylaxis, anaesthetic considerations and heterotopic ossification. Outcomes of arthroplasty include range of movement, pain relief, survivorship and complications.

Whole Genome Expression Profiling and Signal Pathway Screening of MSCs in Ankylosing Spondylitis

The pathogenesis of dysfunctional immunoregulation of mesenchymal stem cells (MSCs) in ankylosing spondylitis (AS) is thought to be a complex process that involves multiple genetic alterations. In this study, MSCs derived from both healthy donors and AS patients were cultured in normal media or media mimicking an inflammatory environment. Whole genome expression profiling analysis of 33,351 genes was performed and differentially expressed genes related to AS were analyzed by GO term analysis and KEGG pathway analysis. Our results showed that in normal media 676 genes were differentially expressed in AS, 354 upregulated and 322 downregulated, while in an inflammatory environment 1767 genes were differentially expressed in AS, 1230 upregulated and 537 downregulated. GO analysis showed that these genes were mainly related to cellular processes, physiological processes, biological regulation, regulation of biological processes, and binding. In addition, by KEGG pathway analysis, 14 key genes from the MAPK signaling and 8 key genes from the TLR signaling pathway were identified as differentially regulated. The results of qRT-PCR verified the expression variation of the 9 genes mentioned above. Our study found that in an inflammatory environment ankylosing spondylitis pathogenesis may be related to activation of the MAPK and TLR signaling pathways.