Genetics and the Causes of Ankylosing Spondylitis

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.

No genetic causal association between periodontitis and ankylosing spondylitis: a bidirectional two-sample mendelian randomization analysis

BACKGROUND

Observational studies that reveal an association between periodontitis (PD) and ankylosing spondylitis (AS) exist. However, observational research is prone to reverse causality and confounding factors, which make it challenging to infer cause-and-effect relationships. We conducted a two-sample Mendelian randomization (MR) study to examine the causal relationship between the genetic prediction of PD and AS.

METHODS

In our study, single-nucleotide polymorphisms (SNPs) were defined as instrumental variables (IVs). The genetic association with PD came from the Gene-Lifestyle Interactions and Dental Endpoints (GLIDE) consortium, wherein 17353 cases of European ancestry and 28210 controls of European ancestry were included in this study. The genetic association with AS from the Neale Laboratory Consortium included 337,159 individuals from the United Kingdom, with 968 cases and 336,191 controls. MR analysis was mainly performed using the inverse-variance weighted (IVW) method. In addition, the robustness of the study findings was assessed using sensitivity, pleiotropy, and heterogeneity analyses.

RESULTS

Eighteen independent SNPs with P-values significantly smaller than 1 × 10- 5 were used as IV SNPs for PD, while 39 independent SNPs with P-values significantly smaller than 1 × 10- 5 were used as IV SNPs for AS. The results of the IVW method revealed no causal association between PD and AS (odds ratio = 1.00, 95% confidence interval: 0.99953 to 1.00067, P = 0.72). The MR-Egger method did not support the causal association between PD and AS. It is unlikely that horizontal pleiotropy distorts causal estimates based on sensitivity analysis. No significant heterogeneity was observed in the Q test. The ''leave-one-out'' analysis demonstrated that the robustness of our results was unaffected by eliminating any of the IVs. Likewise, no significant causative effect for AS on PD was observed in the inverse MR analysis.

CONCLUSIONS

The study results do not support shared heritability or a causal association between PD and AS.

Heat shock protein-related diagnostic signature and molecular subtypes in ankylosing spondylitis: new pathogenesis insights

Heat shock proteins (HSP) have been associated with a range of persistent inflammatory disorders; however, little research has been conducted on the involvement of HSP in the development of ankylosing spondylitis (AS). The research aims to identify a diagnostic signature based on HSP-related genes and determine the molecular subtypes of AS. We gathered the transcriptional data of patients with AS from the GSE73754 dataset and conducted a literature search for HSP-related genes (HRGs). The logistic regression model was utilized for the identification of hub HRGs associated with AS. Subsequently, these HRGs were employed in the construction of a nomogram prediction model. We employed a consensus clustering approach to identify novel molecular subgroups. Subsequently, we conducted functional analyses, encompassing GO, KEGG, and GSEA, to elucidate the underlying mechanisms between these subgroups. To assess the immunological landscape, we employed the xCell algorithm. Through logistic regression analysis, the four core HRGs (CCT2, HSPA6, DNAJB14, and DNAJC5) were confirmed as potential biomarkers for AS. Subsequent stratification revealed two distinct molecular phenotypes, designated as Cluster 1 and Cluster 2. Notably, Cluster 2 was characterized by the upregulation of pathways pertinent to immune response and inflammation. Our research suggests that the CCT2, HSPA6, DNAJB14, and DNAJC5 exhibit potential as effective blood-based diagnostic biomarkers for AS. These findings contribute to a deeper comprehension of the underlying mechanisms involved in the development of AS and offer potential targets for personalized therapeutic interventions.

[The role of HLA-B27 in the pathogenesis and diagnosis of axial spondyloarthritis : 50 years after discovery of the strong genetic association]

BACKGROUND

The association of the human lymphocyte antigen B27 (HLA-B27) with ankylosing spondylitis (AS), also now called axial spondylarthritis (axSpA), was first described 50 years ago.

OBJECTIVE

This article gives an overview of the available knowledge on the topic.

MATERIAL AND METHODS

This is a narrative review based on the experience of the authors.

RESULTS

The HLA-B27 is a member of the HLA class I family of genes of the major histocompatibility complex (MHC). The prevalence of HLA-B27 in the central European population is approximately 8 %, i.e., the vast majority of carriers of HLA-B27+ remain healthy. The frequency of HLA-B27 shows a decline from north to south. The HLA-B27 explains only 30 % of the genetic burden of axSpA. The prevalence of the disease correlates with the frequency of HLA-B27 in the population, i.e., there are geographic differences. Approximately 60-90 % of patients with axSpA worldwide are HLA-B27+. Some 200 subtypes of HLA-B27 can be differentiated using the polymerase chain reaction (PCR). In Thailand and Sardinia two subtypes were found that are not associated with axSpA. The physiological function of HLA class I molecules is the defence of the organism against microbes. Microbial peptides are presented to the immune system, which can be specifically attacked by CD8+ T‑cells. Genetic polymorphisms of the enzyme endoplasmic reticulum aminopeptidase 1 (ERAP1), which breaks down peptides in the endoplasmic reticulum, are associated only with HLA-B27+ diseases.

DISCUSSION

The pathogenesis of axSpA is unclear but a major hypothesis is that of the arthritogenic peptides. In this it is assumed that potentially pathogenic foreign or autologous peptides can be presented by HLA-B27. If nothing else, HLA-B27 plays an important role in the diagnosis, classification and determination of the severity of axSpA.

Card9/neutrophil signalling axis promotes IL-17A-mediated ankylosing spondylitis

OBJECTIVE

Polymorphisms in the antifungal signalling molecule CARD9 are associated with ankylosing spondylitis (AS). Here, we investigated the cellular mechanism by which CARD9 controls pathogenic Th17 responses and the onset of disease in both experimental murine AS and patients.

METHODS

Experiments in SKG, Card9-/-SKG, neutrophil-deplete SKG mice along with in vitro murine, neutrophil and CD4+ T cell cocultures examined Card9 function in neutrophil activation, Th17 induction and arthritis in experimental AS. In AS patients the neutrophil: Bath Ankylosing Spondylitis Functional Index relationship was analysed. In vitro studies with autologous neutrophil: T cell cocultures examined endogenous CARD9 versus the AS-associated variant (rs4075515) of CARD9 in T cellular production of IL-17A.

RESULTS

Card9 functioned downstream of Dectin-1 and was essential for induction of Th17 cells, arthritis and spondylitis in SKG mice. Card9 expression within T cells was dispensable for arthritis onset in SKG mice. Rather, Card9 expression controlled neutrophil function; and neutrophils in turn, were responsible for triggering Th17 expansion and disease in SKG mice. Mechanistically, cocultures of zymosan prestimulated neutrophils and SKG T cells revealed a direct cellular function for Card9 within neutrophils in the potentiation of IL-17 production by CD4+ T cells on TCR-ligation. The clinical relevance of the neutrophil-Card9-coupled mechanism in Th17-mediated disease is supported by a similar observation in AS patients. Neutrophils from HLA-B27+ AS patients expanded autologous Th17 cells in vitro, and the AS-associated CARD9S12N variant increased IL-17A.

CONCLUSIONS

These data reveal a novel neutrophil-intrinsic role for Card9 in arthritogenic Th17 responses and AS pathogenesis. These data provide valuable utility in our future understanding of CARD9-specific mechanisms in spondyloarthritis .

Diagnosis and Treatment of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory condition primarily affecting the axial bone and sacroiliac joints. Its etiology is complicated and involves genetic variables, demographic factors (age of onset, gender, ethnicity, family history), and environmental variables. It typically manifests in males in their third decade. Galen is credited with first recognizing it, according to historical traditions, but it was not until the 19th century that specific diagnostic criteria were developed. The human leukocyte antigen B27 (HLA-B27) variation, around 20% of the genetic risk, is currently the most significant gene associated with AS susceptibility. Over 100 genes have been connected to AS susceptibility. Clinical signs of AS include stiffness and inflammation in the back, eye inflammation, aortitis (inflammation of the aorta), and spinal ankylosis that impacts posture and fatigue. The dagger sign and sacroiliitis on radiographs, in particular, are crucial for diagnosis. Early inflammatory alterations can be found using modern diagnostic tools such as MRI, and the HLA-B27 gene can help confirm the diagnosis. Overall, 80-95% of people with AS have the HLA-B27 marker. Furthermore, although non-specific, elevated inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, offer supporting evidence. Over time, treatment paradigms have seen significant change. First-line treatments such as non-steroidal anti-inflammatory drugs are no longer the only options, even though disease-modifying anti-rheumatic drugs and biologics, especially tumor necrosis factor blockers, have been developed. Physical therapy, which emphasizes consistent exercise, stretches, and posture maintenance, is extremely helpful in managing AS. Surgical interventions can be required in extreme situations. The significance of the interleukin 23/17 axis in the disease cascade has been demonstrated by recent research. Furthermore, a deeper comprehension of the genetic landscape, mainly the functions of non-HLA-B27 loci, may open the door for more specialized therapies. Early diagnosis and interdisciplinary therapies can improve patient outcomes and quality of life as our understanding of AS grows.

Association between HLA-B*27:04 and genetic susceptibility to ankylosing spondylitis in Hunan Province

OBJECTIVES

Human leukocyte antigen (HLA) B27 is a susceptibility allele of ankylosing spondylitis (AS), and HLA-B27 antigen typing is an important indicator for clinical diagnosis of AS, but current typing methods such as sequence specific primer polymerase chain reaction (PCR-SSP) still possess limitation. Therefore, this study aims to analyze the correlation between B27 subtypes and susceptibility to AS in Hunan Province by applying high-resolution polymerase chain reaction-sequence-based typing (PCR-SBT).

METHODS

Peripheral blood of 116 patients with suspected AS (suspected AS group) and 121 healthy volunteers (control group) admitted to the Second Xiangya Hospital from January 2020 to December 2020 were collected for HLA-B genotyping by PCR-SBT. Among the patients in the suspected AS group, 23 patients were finally diagnosed with AS (confirmed AS group), and the remaining 93 undiagnosed patients served as the non-confirmed AS group. PCR-SBT and PCR-SSP were used to detect HLA-B27 typing in 116 patients with suspected AS, and the results of the 2 methods were compared.

RESULTS

The HLA-B27 allele frequency in the suspected AS group was significantly higher than that in the control group [11.63% vs 2.48%; P<0.001, odds ratio (OR)=5.18, 95% confidence interval (CI) 2.097 to 12.795]. B*27:04, B*27:05, B*27:06, and B*27:07 were detected in the suspected AS group and the control group. The frequency of the B*27:04 allele in the suspected AS group was significantly higher than that in the control group (9.48% vs 1.24%; P<0.001, OR=8.346, 95% CI 2.463 to 28.282). The positive rate of B27 in the suspected AS group and the confirmed AS group (B27+/+ and B27+/-) was significantly higher than that in the control group (χ2=16.579, P<0.001; χ2=94.582, P<0.001, respectively). Among the confirmed AS group, 21 were HLA-B27 carriers, and the B27 positive rate in the confirmed AS group was 91.3%. PCR-SBT could achieve high resolution typing of the HLA-B gene locus, with higher sensitivity, specificity, positive predictive value, negative predictive value, and accuracy than PCR-SSP.

CONCLUSIONS

PCR-SBT typing analysis shows a strong correlation between HLA-B * 27:04 and AS in Hunan province. The PCR-SBT method can be used as the preferred option for the auxiliary diagnosis of clinical AS.

PRICKLE1 gene methylation and abnormal transcription in Chinese patients with ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory arthritis without a reliable biomarker. The role of methylation and mRNA expression of PRICKLE1 promoter in the pathogenesis of ankylosing spondylitis remains unclear.

METHODS

A two-stage case-control design was used to detect the characteristics of methyl group and transcriptome of PRICKLE1 gene in Ankylosing spondylitis. The methylation degree of PRICKLE1 gene promoter region was tested by phosphate-sequencing, and further analyzed whether there was significant difference in methylation level of PRICKLE1 gene. The expression levels of PRICKLE1 mRNA in 50 AS patients and 50 healthy controls were detected by real-time quantitative PCR (RT-qPCR).

RESULTS

Compared with healthy control group, the intensity of methylation in 4 ponds of PRICKLE1 in patients with Ankylosing spondylitis was low, and the mRNA levels were overexpressed (P = 0.017). ROC results showed that the sensitivity of PRICKLE1 was 68.67% and specificity was 71.43%.

CONCLUSION

There is a significant change in the concentration of serum PRICKLE1 mRNA​in patients with Ankylosing spondylitis, and the degree of gene methylation is significantly reduced, suggesting that PRICKLE1 gene maybe involved in the pathogenesis of Ankylosing spondylitis, which may be useful for predicting the occurrence of AS and finding new early screening indicators.

Efficacy of myofascial induction compared with its simulation on joint amplitude in people with axial spondylarthritis: Protocol of a randomized controlled clinical trial

BACKGROUND

Axial spondyloarthritis (AxSpA) produces structural changes that cause alterations in body functions. One tissue that seems to have a predictive role in the etiology and progression of the disease is the soft tissue, particularly the fascia. However, little is known about the use of myofascial induction in people with AxSpA, and clinical evidence from physiotherapy regarding potential strategies is limited.

OBJECTIVE

To evaluate the efficacy of myofascial induction compared with its simulation on joint amplitude in people with AxSpA.

METHODS

In this randomized controlled parallel superiority clinical trial, 84 people with an AxSpA diagnosis confirmed by a rheumatologist will be randomly assigned to groups: the experimental group or the control group. The experimental group will receive myofascial induction, and the control group will undergo a simulation of the technique. Both groups will receive an examination session and six intervention sessions twice per week for three weeks. A baseline follow-up will be performed immediately after the intervention and four weeks after treatment.

CONCLUSION

The results of this study may contribute to a better understanding of the efficacy of myofascial induction for joint mobility in people with AxSpA. The implications of these results have a potential transformative effect on the understanding, analysis, evaluation, and physiotherapeutic treatment of this health condition.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04424589. Registered 11 June 2020.

Revealing mechanism of Methazolamide for treatment of ankylosing spondylitis based on network pharmacology and GSEA

Methazolamide is a carbonic anhydrase (CA) inhibitor with satisfactory safety. Our previous studies have demonstrated the elevation of CA1 expression and the therapeutic effect of Methazolamide in Ankylosing spondylitis (AS). In this study, we explored the pathogenic role of CA1 and the pharmacological mechanism of Methazolamide in AS through Gene Set Enrichment Analysis (GSEA) and network pharmacology. Seven out of twelve CA1 related gene sets were enriched in AS group. CA1 was core enriched in above seven gene sets involving zinc ion binding, arylesterase activity and one carbon metabolic process. Functional analysis of the candidate target genes obtained from the intersection of AS associated genes and Methazolamide target genes indicated that Methazolamide exerts therapeutic effects on AS mainly through inflammatory pathways which regulate the production of tumor necrosis factor, IL-6 and nitric oxide. PTGS2, ESR1, GSK3β, JAK2, NOS2 and CA1 were selected as therapeutic targets of Methazolamide in AS. Molecular docking and molecular dynamics simulations were performed successfully. In addition, we innovatively obtained the intersection of Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses and GSEA results, and found that 18 GO terms and 5 KEGG terms were indicated in the pharmacological mechanism of Methazolamide in AS, involving bone mineralization, angiogenesis, inflammation, and chemokine signaling pathways. Nevertheless, validation for these mechanisms is needed in vivo/vitro experiments.

Fifty years after the discovery of the association of HLA B27 with ankylosing spondylitis

The human lymphocyte antigen B27 (HLA B27) is a member of the HLA class I family of genes in the major histocompatibility complex whose name goes back to its discovery in studies of transplanted tissue compatibility. Its prevalence in the mid-European population is about 8%. The association of HLA B27 alleles with ankylosing spondylitis (AS), a highly heritable disease, which is part of the spectrum of axial spondyloarthritis (axSpA), was discovered 50 years ago. HLA B27 explains less than 30% of the total genetic load. About 60%-90% of axSpA patients worldwide carry HLA B27. The prevalence of the disease is linked to the frequency of HLA B27 in the population which implies that there are relevant differences. Among the roughly 200 subtypes known there are two which are not disease associated. The function of HLA class I molecules is to present peptides to the immune system to defend the organism against microbes targeted by CD8+T cells. This is much supported by the role of the endoplasmic reticulum aminopeptidase 1 (ERAP 1) in AS, an enzyme that is responsible for the intracellular trimming of peptides, since polymorphisms of this gene are only associated with HLA-B27+ disease. The arthritogenic peptide hypothesis trying to explain the pathogenesis of AS is based on that very immune function assuming that also self peptides can be presented. HLA-B27 also plays an important role in classification, diagnosis and severitiy of axSpA.

Screening and identification of key chromatin regulator biomarkers for ankylosing spondylitis and drug prediction: evidence from bioinformatics analysis

BACKGROUND

Ankylosing spondylitis (AS) is one of the most common immune-mediated arthritic diseases worldwide. Despite considerable efforts to elucidate its pathogenesis, the molecular mechanisms underlying AS are still not fully understood.

METHODS

To identify candidate genes involved in AS progression, the researchers downloaded the microarray dataset GSE25101 from the Gene Expression Omnibus (GEO) database. They identified differentially expressed genes (DEGs) and functionally enriched them for analysis. They also constructed a protein-protein interaction network (PPI) using STRING and performed cytoHubba modular analysis, immune cell and immune function analysis, functional analysis and drug prediction.The results showed that DEGs were mainly associated with histone modifications, chromatin organisation, transcriptional coregulator activity, transcriptional co-activator activity, histone acetyltransferase complexes and protein acetyltransferase complexes.

RESULTS

The researchers analysed the differences in expression between the CONTROL and TREAT groups in terms of immunity to determine their effect on TNF-α secretion. By obtaining hub genes, they predicted two therapeutic agents, AY 11-7082 and myricetin.

CONCLUSION

The DEGs, hub genes and predicted drugs identified in this study contribute to our understanding of the molecular mechanisms underlying the onset and progression of AS. They also provide candidate targets for the diagnosis and treatment of AS.

HLA-B27 positivity in a large miscegenated population of 5,389,143 healthy blood marrow donors in Brazil

BACKGROUND

The prevalence of HLA-B27 gene positivity in healthy Caucasian communities varies between 8 and 14%. However, there is a lack of information in countries with a high rate of miscegenation, such as Brazil.

AIM

To estimate the frequency of HLA-B27 in the Brazilian general population using a large national registry database.

METHODS

This is a cross-sectional ecological study using the Brazilian Registry of Volunteer Bone Marrow Donors (REDOME) database on HLA-B27 allelic frequency and proportion of positives of healthy donors (18-60 years old). Data were analyzed according to sex, age, race (by self-reported skin color recommended by the Brazilian Institute of Geography and Statistics - IBGE), and geographic region of residence.

RESULTS

From 1994 to 2022, a total of 5,389,143 healthy bone marrow donors were included. The overall positivity for HLA-B27 was 4.35% (CI 95% 4.32-4.37%), regardless of sex and age (57.2% were women, mean age was 41.7yo). However, there was a difference between races: 4.85% in Whites; 2.92% in Blacks; 3.76% in Pardos (Browns i.e. mixed races); 3.95% in Amarelos (Yellows i.e. Asian Brazilians); and 3.18% in Indigenous. There was also a difference regarding geographic region of residence (North: 3.62%; Northeast: 3.63%; Southeast: 4.29%; Midwest: 4.5% and 5.25% in South). The homozygosity rate for the HLA-B27 was 1.32% of all the positives and only 0.06% in the general population.

CONCLUSIONS

Our findings provide the first Brazilian national prevalence for HLA-B27 in 4.35%. There is a gradient gene positivity from North to South, suggesting that the genetic background related to the miscegenation due to colonization, slavery, and some later waves of immigration together with internal migratory flows, could explain our findings.

Purine metabolites promote ectopic new bone formation in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease that mainly affects the axial skeleton, whose typical features are inflammatory back pain, bone structural damage and pathological new bone formation. The pathology of ectopic new bone formation is still little known. In this study, we found increased purine metabolites in plasma of patients with AS. Similarly, metabolome analysis indicated increased purine metabolites in both serum of CD4-Cre; Ptpn11^fl/fl and SHP2-deficient chondrocytes. SHP2-deficient chondrocytes promoted the growth of wild type chondrocytes and differentiation of osteoblasts in CD4-Cre; Ptpn11^fl/fl mice, which spontaneously developed AS-like bone disease. Purine metabolites, along with PTHrP derived from SHP2-deficient chondrocytes, accelerated the growth of chondrocytes and ectopic new bone formation through PKA/CREB signaling. Moreover, Suramin, a purinergic receptor antagonist, suppressed pathological new bone formation in AS-like bone disease. Overall, these results highlight the potential role of targeting purinergic signaling in retarding ectopic new bone formation in AS.

Clinical study of Tongdu Shujin decoction in the treatment of ankylosing spondylitis with cold-dampness obstruction type: Study protocol for a randomized controlled trial

BACKGROUND

Ankylosing spondylitis (AS) has a high incidence, and severe cases can lead to spinal deformity and even joint fusion, which causes a huge burden on patients life, work and psychology. Tongdu Shujin decoction (TDSJ) has a definite effect in the treatment of ankylosing spondylitis, so we designed a randomized controlled trial to observe the efficacy of TDSJ in the treatment of AS, and to evaluate its safety.

METHODS

In this randomized controlled trial, 80 eligible patients were randomly assigned in a 1:1 ratio to a treatment group TDSJ and a control group (celecoxib capsules in combination with thalidomide tablets) for 8 weeks. Visual analogue scale, bath ankylosing spondylitis disease activity index, bath ankylosing spondylitis functional index, and traditional Chinese medicine syndrome scores will be used as primary indicators. Erythrocyte sedimentation rate, C-reactive protein, spinal mobility (figure-ground distance, occipital tubercle-wall distance, Schober test) will be used as secondary indicators. Vital signs (respiration, heart rate, body temperature, blood pressure, electrocardiogram), blood routine, urine routine, stool routine, liver function, and renal function will be used as safety indicators. The primary and secondary indicators will be detected at 0th and 8th week, while safety indicators at 0th, 4th, and 8th week.

DISCUSSION

This study will provide high-quality clinical evidence for the efficacy and safety of TDSJ in the treatment of AS.

DNA methylation and transcriptome signatures of the PDCD1 gene in ankylosing spondylitis

Ankylosing spondylitis (AS) is an autoimmune-related inflammatory arthritis. The association between the DNA methylation and mRNA expression of PDCD1 gene with the susceptibility to AS remains unclear. In this case-control study, the methylation level of PDCD1 promoter was detected in 80 AS patients and 80 healthy controls by MethylTarget method. The transcriptional level of PDCD1 gene was measured in 47 AS patients and 47 healthy controls by real-time quantitative PCR. Finally, 17 methylation sites mapped to one CpG island were detected. Compared to healthy controls, the promoter of PDCD1 was hypermethylated (p < 0.001) and the mRNA expression was downregulated (p < 0.001) in AS patients. Significantly negative correlation was identified between the DNA methylation and mRNA expression of PDCD1 gene (r_s = -0.470, p < 0.001). The receiver operating characteristic (ROC) results showed that PDCD1 island had a sensitivity of 61.3% and a specificity of 82.5%, and PDCD1 mRNA had a sensitivity of 87.2% and a specificity of 89.0%. The methylation level of PDCD1 was positively correlated with the ESR, CRP and ASDAS of AS, and was not affected by HLA-B27 status, gender or medicine intake.

JAK-STAT signaling pathway-related gene single nucleotide polymorphisms and susceptibility to ankylosing spondylitis in eastern Chinese Han population

OBJECTIVE

A case-control study was utilized to investigate the relationship between genetic variation of JAK-STAT signaling pathway-related genes and the susceptibility to ankylosing spondylitis (AS).

METHODS

Fifteen SNPs in the JAK-STAT signaling pathway-related genes from 660 AS patients and 646 healthy controls were genotyped using iMLDR technology (JAK1: rs2230587, rs2230588, rs2780815, rs310241; JAK2: rs2274472, rs2230722, rs2230724, rs10758669; STAT1: rs10199181, rs1547550, rs2066802, rs45463799, rs6718902; STAT3: rs3744483; STAT5A: rs1135669).

RESULTS

Allele analysis revealed that the T allele of STAT1 rs6718902 was a protective agent for male AS patients (OR = 0.765, 95% CI = 0.644-0.909). Inheritance models showed that GG + CG as well as GG genotypes of STAT1 rs1547550 had a significant risk of developing AS in males (OR = 5.374, 95%CI = 2.505-11.526; OR = 5.186, 95%CI = 2.412-11.153). The TT + CT and TT genotypes at STAT1 rs6718902 were observed to be associated with a significantly decreased risk of AS compared to CC genotypes among male patients and male controls (OR = 0.637, 95%CI = 0.485-0.837; OR = 0.597, 95%CI = 0.422-0.845). Furthermore, the genotypes of JAK1 gene rs2230588, rs2780815, and rs310241 were correlated with the severity of clinical conditions in female AS patients, while the JAK2 rs2230724 genotypes may affect disease ability in male AS patients.

CONCLUSION

These findings indicated that JAK-STAT signaling pathway-related gene single nucleotide polymorphisms may be associated with AS susceptibility in eastern Chinese Han population. Key Points • The T allele of rs6718902 on the STAT1 gene may be a protective agent for male AS patients. • STAT1 rs1547550 GG + CG and GG genotypes were observed to be connected with a risk of male AS patients. However, STAT1 rs6718902 TT + CT and TT genotypes reduced the susceptibility risk of male AS patients compared to wild-type CC. • The JAK1 genes rs2230588, rs2780815, and rs310241 may affect disease functional status in female AS patients, while the JAK2 rs2230724 genotype was related to disease activity in male AS patients.

Effectiveness of interleukin-17A inhibitors in patients with ankylosing spondylitis: A protocol for systematic review and meta-analysis

BACKGROUND

Ankylosing spondylitis is a chronic immune-mediated inflammatory arthritis. Interleukin-17A (IL-17A) inhibitors is recognized as a novel therapeutic target for ankylosing spondylitis. However, there is still a lack of high-quality research evidence regarding the issues. Therefore, we performed a protocol for systematic review and meta-analysis to evaluate the efficacy and safety of IL-17A inhibitors in patients with ankylosing spondylitis.

METHODS

This protocol will be conducted under the preferred reporting items for systematic reviews and meta-analyses protocols (PRISMA-P) guidelines. Furthermore, the study has been registered on PROSPERO (CRD42022375885). The following electronic databases will be searched regardless of language and publication status: Pubmed, MEDLINE, EMBASE, China Biomedical Database, China National Knowledge Infrastructure, VIP Database, and Wanfang Database. Cochrane "bias risk" tool is used to assess the bias risk of the quality of the included literature. Data synthesis and statistical analysis will be performed using the RevMan 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) software.

RESULTS

A synthesis of current evidence of IL-17A inhibitors for ankylosing spondylitis will be shown in this protocol.

CONCLUSION

This review can provide convincing evidence to help clinicians make decisions when dealing with ankylosing spondylitis.

The Presence of Ankylosing Spondylitis and the Incidence of Subsequent External Eye Diseases: A Population-Based Cohort Study

We aimed to survey the risk of external eye diseases in those with ankylosing spondylitis (AS) via the National Health Insurance Research Database (NHIRD) in Taiwan. We conducted a retrospective cohort study, and subjects diagnosed with AS were selected from the NHIRD. Then, the AS patients were matched 1:1 by propensity-score matching (PSM) to non-AS patients, and a total of 6754 participants were included in the AS and non-AS groups. The main outcomes were regarded as the occurrence of dry eye disease (DED), superficial keratopathy and corneal ulcers. We used Cox proportional hazard regression to yield the adjusted hazard ratios (AHR) with 95% confidence intervals (CI) between the AS and non-AS groups. There were 709 and 408 external eye disease events that occurred in the AS and non-AS groups after a tracking interval of up to 17 years. The incidence of all external eye diseases was significantly higher in the AS group than the non-AS group (AHR: 1.826, 95% CI: 1.616−2.063, p < 0.0001). Additionally, the rates of DED (AHR: 1.973, 95% CI: 1.701−2.290, p < 0.0001) and superficial keratopathy (AHR: 1.593, 95% CI: 1.347−1.883, p < 0.0001) were significantly higher in the AS group than the non-AS group. In the sub-group analyses, the possibility of any external eye disease (p = 0.0030) and DED (p = 0.0386) was decreased in the older age group compared to those in the middle-aged group. In conclusion, AS is significantly correlated to subsequent external eye diseases, mainly the DED and superficial keratopathy.

Ankylosing spondylitis disease activity and serum vitamin D levels: A systematic review and meta-analysis

BACKGROUND

To prove that serum vitamin D (VD) levels are strongly associated with ankylosing spondylitis (AS) disease activity, the association between serum VD levels and key monitoring indicators of AS disease activity has been analyzed, such as the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).

METHODS

Studies published in PubMed, Cochrane Library, EMBASE, and China National Knowledge Infrastructure by August 30, 2022 were searched, and 6 studies finally met the selection criteria. Serum 25-hydroxyvitamin D (25(OH)D), ESR, CRP levels, and correlation coefficients between serum VD and BASDAI, ESR, CRP in AS, and control in these studies were extracted for the meta-analysis.

RESULTS

When compared to controls, patients with AS had considerably lower blood 25(OH)D levels (MD = -7.53 ng/mL, 95% CI, -9.78 to -5.28, P < .001) and significantly higher ESR and CRP levels (ESR: MD = 11.75 mm/h, 95% CI, 4.20 to 19.31, P = .002; CRP: MD = 15.36 mg/L, 95% CI, 4.95 to 25.77, P = .004). Additionally, a negative correlation was discovered between serum VD levels and BASDAI, ESR, and CRP (Fisher' Z = -0.34, -0.38, -0.35, respectively).

CONCLUSION

The findings of our meta-analysis demonstrated a negative correlation between serum VD levels and the main monitoring indices of disease activity in patients with AS and verified that the differences in the continent and ethnicity may be one of the major contributors to this finding.

Ezetimibe ameliorates clinical symptoms in a mouse model of ankylosing spondylitis associated with suppression of Th17 differentiation

Ankylosing spondylitis (AS) is a chronic inflammatory disease that causes spinal inflammation and fusion. Although the cause of AS is unknown, genetic factors (e.g., HLA-B27) and environmental factors (e.g., sex, age, and infection) increase the risk of AS. Current treatments for AS are to improve symptoms and suppress disease progression. There is no way to completely cure it. High blood cholesterol and lipid levels aggravate the symptoms of autoimmune diseases. We applied hyperlipidemia drugs ezetimibe and rosuvastatin to AS mice and to PBMCs from AS patients. Ezetimibe and rosuvastatin was administered for 11 weeks to AS model mice on the SKG background. Then, the tissues and cells of mice were performed using flow cytometry, computed tomography, immunohistochemistry, and immunofluorescence. Also, the normal mouse splenocytes were cultured in Th17 differentiation conditions for in vitro analysis such as flow cytometry, ELISA and RNA sequencing. The 10 AS patients’ PBMCs were treated with ezetimibe and rosuvastatin. The patients’ PBMC were analyzed by flow cytometry and ELISA for investigation of immune cell type modification. Ezetimibe caused substantial inhibition for AS. The present study showed that ezetimibe inhibits Th17 cell function, thereby slowing the progression of AS. It is well known that statins are more effective in reducing blood lipid concentrations than ezetimibe, however, our results that ezetimibe had a better anti-inflammatory effect than rosuvastatin in AS. This data suggests that ezetimibe has an independent anti-inflammatory effect independent of blood lipid reduction. To investigate whether ezetimibe has its anti-inflammatory effect through which signaling pathway, various in vitro experiments and RNA sequencing have proceeded. Here, this study suggests that ezetimibe can be an effective treatment for AS patients by inhibiting Th17 differentiation-related genes such as IL-23R and IL-1R. Thus, this study suggests that ezetimibe has therapeutic potential for AS through inhibition of Th17 differentiation and the production of pro-inflammatory cytokines.

DNA Methylation and mRNA Expression of B7-H3 Gene in Ankylosing Spondylitis: A Case-Control Study

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory arthritis, with a high prevalence in patients in their mid-20s. Its pathogenesis is not well understood; however, genetic factors likely play a critical role. Epigenetic DNA changes may be involved in the pathogenesis of AS. In this study, we explored the methylation and transcription levels of the B7-H3 gene and its association with AS in an eastern Chinese Han population.

METHODS

Peripheral blood of AS patients and healthy controls was used to extract genomic DNA and B7-H3 methylation levels were analyzed using sodium bisulfite followed by multiplex polymerase chain reaction. SPSS software was used to determine the statistical significance of the results.

RESULTS

Hypomethylation of the promoter of the B7-H3 gene was observed in AS patients, whereas the B7-H3 gene expression was significantly enhanced in AS patients.

CONCLUSION

Epigenetic modifications of B7-H3 were associated with susceptibility to AS. Hypomethylation of the B7-H3 promoter, which leads to B7-H3 overexpression, may be involved in the pathogenesis of AS.

HLA-B27 may modulate the interaction between ERAP1 polymorphisms and smoking in ankylosing spondylitis patients

BACKGROUND

Ankylosing spondylitis (AS) is an autoimmune disease that affects the enthesis and synovial membrane of the spine, the sacroiliac vertebrae and peripheral joints. Genetic susceptibility to AS is mainly due to the presence of the HLA-B*27 (B27) allele, and endoplasmic reticulum aminopeptidase-1 (ERAP-1) plays a key role in antigen processing and presentation to HLA class I molecules. Tobacco consumption is one of the main environmental factors involved in the pathogenesis of various diseases, including AS. The objective of the present study was to evaluate the association and the interactive effects of variants of the ERAP1 gene with smoking in modulating the risk of AS.

METHODS AND RESULTS

A case-control study in the Mexican population. The association of two functional variants of the ERAP1 gene (rs30187 and rs27044) in patients with AS was analyzed by the allelic discrimination method using TaqMan probes. B27 was typified by PCR-SSP. The interaction between the variants of ERAP1 and B27 and smoking was assessed using the multifactorial dimensionality reduction (MDR) method. There was no significant association of the two variants of ERAP1 in the cases compared with the controls (P > 0.05); however, a strong interaction between the variants and smoking could be demonstrated, with entropy values of 4.97% for rs30187 and 5.13% for rs27044. In addition, these interaction effects were increased in patients carrying the B27 allele.

CONCLUSIONS

The rs30187 and rs27044 variants of the ERAP1 gene appear to potentiate the effect of smoking in patients with AS carrying the B27 allele.

DNA methylation and transcription of the FOXO3a gene are associated with ankylosing spondylitis

To explore the association between methylation level and transcript level of Forkhead box O3a (FOXO3a) gene with ankylosing spondylitis (AS) susceptibility. Methylation levels of the FOXO3a promoter were measured in 84 AS patients and 83 healthy controls. A total of 77 patients and 66 healthy subjects were included in subsequent mRNA level testing. DNA methylation levels of 107 CpG sites on 6 CpG islands in the FOXO3a gene were investigated. This study indicated that CpG-4 and CpG-5 islands were markedly hypomethylated in AS patients. The methylation level of CpG-4 island in AS patients was negatively correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Ankylosing Spondylitis Disease Activity Score (ASDAS). Moreover, FOXO3a mRNA levels were significantly decreased in AS patients and were obviously negatively correlated with the methylation levels of CpG-2 and CpG-5 islands in AS patients without treatment. The sensitivity and specificity of differential methylated CpG sites of FOXO3a were 74.7 and 85.4%, respectively. Besides, FOXO3a mRNA had a sensitivity of 80.0% and a specificity of 68.8%. DNA methylation and transcription of FOXO3a might be related to AS susceptibility and play a crucial role in the diagnosis of AS, but many open questions remain.

miR‑150‑5p inhibits osteogenic differentiation of fibroblasts in ankylosing spondylitis by targeting VDR

Dysregulated microRNAs (miRNAs or miRs) serve potential roles in inflammatory systemic disease, including ankylosing spondylitis (AS). The aim of the present study was to investigate the potential function of miR-150-5p in osteogenic differentiation of AS fibroblasts and its underlying mechanism. The expression of miR-150-5p and vitamin D receptor (VDR) in AS joint capsules and fibroblasts was detected by reverse transcription-quantitative (RT-q)PCR and western blotting. Following overexpression of miR-150-5p, the alteration in osteogenic gene expression was detected by RT-qPCR, western blotting and alkaline phosphatase activity assay, as well as alizarin red staining. The association between miR-150-5p and VDR was confirmed by luciferase assay and rescue experiments were performed. Patients with AS exhibited decreased expression of miR-150-5p in joint capsules. Treatment with bone morphogenic protein 2 (BMP-2) and transforming growth factor-β1 (TGF-β1) led to downregulation of miR-150-5p in AS fibroblasts. Enforced expression of miR-150-5p attenuated osteogenic differentiation of AS fibroblasts. These results demonstrated that miR-150-5p inhibited osteogenic differentiation of AS fibroblasts by targeting VDR. miR-150-5p overexpression decreased osteogenic transformation of fibroblasts by decreasing VDR expression in AS.

Tofacitinib for the treatment of active ankylosing spondylitis in adults

INTRODUCTION

Ankylosing spondylitis, also known as radiographic axial spondyloarthritis, is a complex, immune-mediated inflammatory disorder most commonly involving the spine including the sacroiliac joints.

AREAS COVERED

Complex pathogenesis of axial spondyloarthritis involving genetic, environmental, and both innate and adaptive immune systems. Treatment options for ankylosing spondylitis. Pharmacologic properties, efficacy, and safety of tofacitinib, a JAK inhibitor. Data regarding efficacy of approved JAK inhibitors in the treatment of ankylosing spondylitis, including tofacitinib, upadacitinib, and filgotinib.

EXPERT OPINION

Current treatment options of ankylosing spondylitis include NSAIDs, TNFi, and IL-17i. JAK inhibitors present a new class of therapy that has shown efficacy in the treatment of active ankylosing spondylitis in adults. While it has not been directly compared to alternate therapies, tofacitinib has been shown to be effective in both phase II and phase III trials for the treatment of ankylosing spondylitis. While these trials did not show any significant difference from placebo in terms of safety, the ORAL Surveillance study showed tofacitinib to be inferior to TNFi when comparing adverse events. Thus, tofacitinib presents a viable treatment option for the management of AS, however shared decision making regarding risks and benefits will be important.

The Potential Role of Genetics, Environmental Factors, and Gut Dysbiosis in the Aberrant Non-Coding RNA Expression to Mediate Inflammation and Osteoclastogenic/Osteogenic Differentiation in Ankylosing Spondylitis

Ankylosing spondylitis (AS) or radiographic axial spondyloarthritis is a chronic immune-mediated rheumatic disorder characterized by the inflammation in the axial skeleton, peripheral joints, and soft tissues (enthesis, fascia, and ligament). In addition, the extra-skeletal complications including anterior uveitis, interstitial lung diseases and aortitis are found. The pathogenesis of AS implicates an intricate interaction among HLA (HLA-B27) and non-HLA loci [endoplasmic reticulum aminopeptidase 1 (ERAP1), and interleukin-23 receptor (IL23R), gut dysbiosis, immune plasticity, and numerous environmental factors (infections, heavy metals, stress, cigarette smoking, etc.) The latter multiple non-genetic factors may exert a powerful stress on epigenetic regulations. These epigenetic regulations of gene expression contain DNA methylation/demethylation, histone modifications and aberrant non-coding RNAs (ncRNAs) expression, leading to inflammation and immune dysfunctions. In the present review, we shall discuss these contributory factors that are involved in AS pathogenesis, especially the aberrant ncRNA expression and its effects on the proinflammatory cytokine productions (TNF-α, IL-17 and IL-23), T cell skewing to Th1/Th17, and osteoclastogenic/osteogenic differentiation. Finally, some potential investigatory approaches are raised for solving the puzzles in AS pathogenesis.

Clinical phenotype and musculoskeletal characteristics of patients with aggrecan deficiency

Aggrecan is a proteoglycan within the physeal and articular cartilage. Aggrecan deficiency, due to heterozygous mutations in the ACAN gene, causes dominantly inherited short stature and, in many patients, early-onset osteoarthritis and degenerative disc disease. We aimed to further characterize this phenotypic spectrum with an emphasis on musculoskeletal health. Twenty-two individuals from nine families were enrolled. Histories and examinations focused on joint health, gait analysis, joint specific patient reported outcomes, and imaging studies were performed. All patients had dominantly inherited short stature, with the exception of a de novo mutation. Short stature was worse in adults versus children (median height -3.05 SD vs. -2.25 SD). ACAN mutations were not always associated with bone age advancement (median advancement +1.1 years, range 0 to +2 years). Children had subtle disproportionality and clinically silent joint disease-25% with osteochondritis dissecans (OD). Adults had a high prevalence of joint symptomatology-decline in knee function, disability from spinal complaints, and lower physical activity on outcome measures. Osteoarthritis (OA) and OD was detected in 90% of adults, and orthopedic surgeries were reported in 60%. Aggrecan deficiency leads to short stature with progressive decline in height SD, mild skeletal dysplasia, and increasing prevalence of joint pathology over time. Optimal musculoskeletal health and quality of life can be attained with timely identification of pathology and intervention.

Integrative blood-derived epigenetic and transcriptomic analysis reveals the potential regulatory role of DNA methylation in ankylosing spondylitis

Background

The currently known risk loci could explain a small proportion of the heritability of ankylosing spondylitis (AS). Epigenetics might account for the missing heritability. We aimed to seek more novel AS-associated DNA methylation alterations and delineate the regulatory effect of DNA methylation and gene expression with integrated analysis of methylome and transcriptome.

Methods

Epigenome-wide DNA methylation and mRNA expression were profiled in peripheral blood mononuclear cells (PBMCs) from 45 individuals (AS: health controls (HCs) = 30:15) with high-throughput array. The methylome was validated in an independent cohort (AS: HCs = 12:12). Pearson correlation analysis and causal inference tests (CIT) were conducted to determine potentially causative regulatory effects of methylation on mRNA expression.

Results

A total of 4794 differentially methylated positions (DMPs) were identified associated with AS, 2526 DMPs of which were validated in an independent cohort. Both cohorts highlighted T cell receptor (TCR) signaling and Th17 differentiation pathways. Besides, AS patients manifested increased DNA methylation variability. The methylation levels of 158 DMPs were correlated with the mRNA expression levels of 112 genes, which formed interconnected network concentrated on Th17 cell differentiation and TCR signaling pathway (LCK, FYN, CD3G, TCF7, ZAP70, CXCL12, and PLCG1). We also identified several cis-acting DNA methylation and gene expression changes associated with AS risk, which might regulate the cellular mechanisms underlying AS.

Conclusions

Our studies outlined the landscapes of epi-signatures of AS and several methylation-gene expression-AS regulatory axis and highlighted the Th17 cell differentiation and TCR signaling pathway, which might provide innovative molecular targets for therapeutic interventions for AS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02697-3.

Ankylosing Spondylitis Patients Display Aberrant ERAP1 Gene DNA Methylation and Expression

BACKGROUND

Endoplasmic reticulum aminopeptidase 1 (ERAP1) is known to participate in the pathogenesis of ankylosing spondylitis (AS). This study aimed to evaluate the relationship between promoter methylation and mRNA levels of ERAP1 and AS susceptibility.

METHODS

DNA methylation levels of 100 AS patients and 100 healthy controls (HCs) were tested using a targeted bisulfite sequencing assay. To verify the results of DNA methylation, mRNA levels of ERAP1 were measured in 20 AS patients and HCs used quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

The DNA methylation levels of two CpG islands containing 31 loci in ERAP1 promoter were measured. ERAP1_1 (P< .001) and ERAP1_2 (P< .001) islands were significantly hypermethylated in AS patients compared with HCs. In the verification study, the mRNA levels of ERAP1 were significantly decreased in AS patients. The ROC curve analysis showed that the sensitivity, specificity and area under curve were 0.717, 0.737, and 0.779 of differential methylated CpG loci of ERAP1 for AS diagnosis. In AS patients, the methylation levels of EARP1 were associated with family history, non-steroidal anti-inflammatory drugs use, X-ray classification, and clinical manifestations.

CONCLUSIONS

Our study demonstrated that the ERAP1 gene is significantly hypermethylated, and mRNA levels of EARP1 decreased, in AS patients. Our findings suggested that the aberrant methylation of ERAP1 promoter may be involved in the pathogenesis of AS and could be considered as a diagnostic tool and therapeutic target of AS.Abbreviations AS: Ankylosing Spondylitis; AUC: Area Under Curve; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Functional Index; CI: Confidence Interval; CpG: Cytosine-guanine Dinucleotide; CRP: C-reactive Protein; ERAP1: Endoplasmic Reticulum Aminopeptidase 1; ESR: Erythrocyte Sedimentation Rate; EWAS: Epigenome-Wide Association Study; HLA: Human Leukocyte Antigen; OR: Odds Ratio; PCR: Polymerase Chain Reaction; ROC: Receiver Operating Characteristic; NSAIDs: Non-Steroidal Anti-Inflammatory Drugs.

The relationship between platelet to albumin ratio and disease activity in axial spondyloarthritis patients

OBJECTIVES

The study aims to investigate the clinical significance of platelet to albumin ratio (PAR), neutrophil to albumin ratio (NAR), and monocyte to albumin ratio (MAR) in axial spondyloarthritis (axSpA).

METHODS

Two hundred and ninety-seven axSpA patients and 71 healthy volunteers were recruited. AxSpA patients were divided into inactive group and active group. Spearman's correlation, receiver operating characteristic (ROC) curves, and binary logistic regression analysis were conducted.

RESULTS

Albumin was lower in axSpA group, while neutrophil, platelet, monocyte, NAR, PAR, and MAR were higher (p < .05). Albumin was negatively correlated with BASDAI and BASFI (p < .05). Platelet, NAR, PAR, MAR, ESR, and CRP were all positively correlated with BASDAI and BASFI (p < .05). Albumin was lower in axSpA of active group, while platelet, NAR, PAR, MAR, ESR, and CRP were higher (p < .05). ROC curve indicated that the AUC of PAR for axSpA of active group was higher than that of other variables. The optimal cut-off value of PAR was 6.354, with Youden index of 0.337, specificity of 55.4%, and sensitivity of 78.4%. Logistic regression analysis result suggested that PAR was an independent indicator for axSpA disease activity.

CONCLUSIONS

PAR had a high diagnostic value for axSpA of active group. PAR was a novel and reliable indicator for axSpA disease activity.

Risk factors for radiological hip involvement in patients with ankylosing spondylitis

OBJECTIVE

Our study aimed to explore the potential risk factors for radiological hip joint involvement in patients with ankylosing spondylitis (AS).

METHODS

This cross-sectional convey collected the clinical data, laboratory indicators, and radiographic data of patients with AS. Radiographic hip joint involvement was defined as a Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-hip) score ≥2. Multivariate logistic regression analyses were conducted to explore the potential risk factors for radiological hip involvement in patients with AS.

RESULTS

Based on BASRI-hip score, all enrolled 386 patients with AS were classified as patients involving with radiological hip joint involvement (BASRI-hip ≥2; n=203) and those without it (BASRI-hip ≤1; n=183). Mean age of enrolled patients with AS were 36.7±11.9 years, and 320 (82.9%) patients were male. Mean course of disease was 10.7±8.3 years, and 349 (90.4%) patients were with a positive HLAB27. Multivariate analyses indicated that Juvenile onset (onset age ≤16 years) (odds ratio [OR]=4.159, 95% confidence interval [CI], 1.779-9.721, p<0.001), body mass index (BMI) <18.5 kg/m2 (OR=1.986, 95%CI 1.187-3.323, p=0.009), continuous nonsteroidal anti-inflammatory drug (NSAID) use (OR=0.351, 95%CI 0.155-0.794, p=0.012), and bone mass below the expected range for age (Z score ≤-2) (OR=2.791, 95%CI 1.456-5.352, p=0.002) were independently associated with radiological hip joint involvement in patients with AS.

CONCLUSIONS

The potential risk factors for radiological hip joint involvement were juvenile onset, lower BMI, and bone mass below the expected range for age. Furthermore, continuous NSAID use was the protective factor for radiological hip joint involvement in these population.

Genetics, Epigenetics, and Gender Impact in Axial-Spondyloarthritis Susceptibility: An Update on Genetic Polymorphisms and Their Sex Related Associations

Spondyloarthritis (SpA) is a group of chronic inflammatory rheumatic disease that can be divided into predominantly axial or predominantly peripheral involvement, with or without associated psoriasis, inflammatory bowel disease or previous infection. Axial SpA (axSpA) encompasses ankylosing spondylitis (AS) with radiological sacroiliitis, and a type without radiographic sacroiliitis, called “non-radiographic axial SpA” (nr-axSpA). Males and females show large differences in their susceptibility to SpA, such as distinctions in clinical patterns, phenotypes and in therapeutical response, particularly to TNF inhibitors (TNFi). Several studies indicate that AS women have doubled risk to failure TNFi compared with males. This diversity in drugs’ efficacy among women and men may be caused by differences in the balance of sex hormones and in gene-specific expression likely triggered by X-chromosome instability and gene-specific epigenetic modifications. Evidence reported that polymorphisms in microRNAs on X- and other chromosomes, such as miR-146a, miR-155, miR-125a-5p, miR-151a-3p and miR-22-3p, miR-199a-5p could be involved in the different clinical presentation of SpA, as well as disease activity. In addition, association with non−response to TNFi treatment and presence of IRAK3 and CHUCK genes in SpA patients was recently detected. Finally, polymorphisms in genes involved in IL-23/IL-17 pathway, such as in drug pharmacodynamics and pharmacokinetics may have a role in response to TNFi, IL17i, and IL23i. A major understanding of genomic variability could help in the development of new therapeutic targets or in taking advantages of different mechanisms of action of biological drugs. Moving from the multifactorial etiology of disease, the present review aims at evaluating genetic and epigenetic factors and their relationship with sex and bDMARDs response, helping to investigate the different expression among males and females of genes on X- and other chromosomes, as well as mi-RNA, to highlight relationships between sex and occurrence of specific phenotypes and symptoms of the disease. Moreover, the role of the epigenetic modification in relation to immune-regulatory mechanisms will be evaluated.

Association of FOXO3a gene polymorphisms and ankylosing spondylitis susceptibility in Eastern Chinese Han population

OBJECTIVE

To investigate the association of FOXO3a polymorphisms and ankylosing spondylitis (AS) susceptibility in Eastern Chinese Han population.

METHODS

FOXO3a polymorphisms rs12206094, rs12212067, rs2253310, rs3800232, and rs4946933 were genotyped in 650 AS patients and 646 controls by the improved Multiple Ligase Detection Reaction.

RESULTS

The distribution of genotype in rs12212067 polymorphism was significantly different between AS patients and controls (P = 0.020), especially in male population (P = 0.009). There was significant difference of the genotype frequency distribution at rs3800232 between patients and controls in male population. The results of binary regression analysis showed that the rs12212067 GG genotype and rs3800232 TT genotype were obviously correlated with elevated AS risk, and the associations were still significant after being adjusted by age and gender (all P < 0.05). Interestingly, rs12212067 and rs3800232 genotypes were associated with disease activity of patients. Additionally, haplotype block rs12212067^G- rs3800232^T (OR = 1.403, 95%CI = 1.011-1.949) was further shown to confer promoting effect on developing AS.

CONCLUSION

Among Eastern Chinese Han population, FOXO3a polymorphism rs12212067 and rs3800232 may contribute to increased risk of developing AS, but well-designed multicenter studies are needed to further confirm these preliminary findings in the future.

Diagnosing axial spondyloarthritis by multidiciplinary team conference at 3.5 years' follow-up in a cohort of patients with disease features according to the ASAS criteria

OBJECTIVES

During the past two decades, magnetic resonance imaging (MRI) has increasingly been used diagnostically in axial spondyloarthritis (axSpA), and in 2009 MRI was introduced in the Assessment of SpondyloArthritis Society (ASAS) classification criteria. In clinical practice, there is a risk of overdiagnosis if MRI findings are not related to clinical and biochemical findings. The aim of this study was to provide an estimate of the prevalence of axSpA in a cohort of clinical patients with low back pain and findings suggestive of axSpA according to ASAS through consensus diagnosis at a multi-disciplinary team (MDT) conference, and to describe the performance of the features included in the ASAS criteria.

METHOD

Consensus diagnoses of axSpA at MDT conferences were retrospectively established at 3.5 years' follow-up in a cohort of 84 patients, initially referred with disease features according to the ASAS criteria. Patients were examined clinically regarding spondyloarthritis features, and biochemical tests and MRI of the sacroiliac joints and entire spine were performed at baseline and after a mean of 3.5 years.

RESULTS

According to the MDT consensus, 25 patients (30%) of the total cohort had axSpA at follow-up; 40% of individuals who fulfilled the ASAS criteria at baseline had axSpA, and 37% at follow-up; 96% of axSpA patients according to the MDT consensus met the ASAS criteria at baseline and 92% at follow-up.

CONCLUSION

Approximately one-third of the included patients had axSpA when evaluated at the MDT conference. The ASAS criteria had low predictive value, but high sensitivity at both baseline and follow-up.

Underweight and obesity are strong predictors of clinical outcomes in patients with ankylosing spondylitis: data from the Smart-phone SpondyloArthritis Management System

Background

The aim of this study was to examine the impact of underweight, overweight and obesity on clinical outcomes and treatment responses to biologics in Chinese patients with ankylosing spondylitis (AS).

Methods

Body mass index (BMI) was available in 1074 patients from the Smart-phone SpondyloArthritis Management System. Patients were categorized into four groups based on BMI: underweight, normal weight, overweight and obesity. Multivariable median regression analyses examined the effect of underweight and obesity on clinical outcomes and treatment response to biologics.

Results

Among 1074 patients with AS, normal weight accounted for 49.1%, while underweight, overweight, and obesity for 8.1%, 30.1%, and 12.0%, respectively. Compared to patients with normal weight, patients with underweight, overweight and obesity had an increased disease activity, while patients with underweight and obesity had a significantly poor Bath Ankylosing Spondylitis Functional Index and Assessment of Spondyloarthritis International Society Health Index scores. For tumor necrosis factor (TNF)-α inhibitor users, BMI was found to be negatively correlated with changes in disease activity in the multivariate regression model (all p < 0.05). Besides, the patients using TNF-α inhibitor in the overweight or obesity categories were much less likely to achieve a significant reduction on disease activity during follow-up period in the multivariate regression model (all p < 0.05), taking these with normal-weight patients as a reference.

Conclusions

Both underweight and obesity except for overweight were associated independently with worse disease activity, physical function and health status. Overweight and obesity might impact on treatment responses to biologics in patients with AS. This argues that weight management, to maintain it at a normal level, should be one of the disease management strategies in patients with AS.

Effectiveness and safety of Chinese herbal formula combined with western medicine for ankylosing spondylitis: A protocol for systematic review and meta-analysis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic progressive inflammatory disease of the spine, which mainly invades the sacroiliac joint, spine, and large joints near the trunk, leading to fibrous and skeletal ankylosis and deformity, and can cause damage to the eyes, lung, cardiovascular, kidney and other organs. Chinese herbal formulas (CHF) is an important interventions of Traditional Chinese Medicine (TCM), and CHFs combined with western medicine are widely used in clinical practice to treat AS.

METHODS

Eight databases will be systematically retrieved from their inceptions to March 2021. Only randomized controlled trials (RCTs) of CHFs combined with western medicine for AS treatment will meet the inclusion criteria. The primary outcomes we focus on include clinical effectiveness rate, TCM syndrome score, TCM symptom score, Bath ankylosing spondylitis disease activity index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), chest expansion, nocturnal spinal pain, adverse reactions, erythrocyte sedimentation rate (ESR), and C protein response (CRP). The research screening, data extraction, and risk of bias assessment will be performed independently by 2 researchers, and divergence will be solved by a third researcher. Revman 5.3 software will be used for meta-analysis. The confidence of evidence will be graded using grading of recommendations assessment, development, and evaluation (GRADE) algorithm and methodological quality will be assessed adopting risk of bias in systematic reviews (ROBIS).

RESULTS

This systematic review (SR) will provide evidence-based medical evidence for AS therapy by CHF combined with western medicine and we will submit the findings of this SR for peer-review publication.

CONCLUSIONS

This SR will provide latest and updated summary proof for assessing the effectiveness and safety of CHF combined with western medicine for AS.

REGISTRATION NUMBER

INPLASY 202150089.

Association of methylation level and transcript level in TRAF5 gene with ankylosing spondylitis: a case-control study

To explore the association between methylation level and transcript level of TNF receptor-associated factor 5 (TRAF5) gene with ankylosing spondylitis (AS) in Chinese Han population. Methylation and mRNA expression level of the TRAF5 gene were tested in 98 patients and 98 healthy controls. Among the 21 CpG sites, methylation levels at eight sites were significantly different between AS patients and healthy controls. However, only three sites remained significantly different after the correction by the Benjamini-Hochberg method. Compared with controls, the CpG island of TRAF5 gene promoter was highly methylated in AS patients, and the relative mRNA expression level of TRAF5 was significantly reduced in AS patients. And the mRNA level was negatively correlated with the methylation level of TRAF5 gene in AS patients (r_s = -0.453, P < 0.001). Subgroup analyses indicated that there was no significant difference in the level of methylation between groups of different status of HLA-B27 and medications in AS patients. Multiple linear regression showed that disease-modifying antirheumatic drugs could reduce methylation levels of AS patients after adjusting for the effects of other drugs. In conclusion, the hypermethylation of the TRAF5 might contribute to the pathogenesis of AS, but many open questions remain.

Efficacy of warming needle moxibustion in the treatment of ankylosing spondylitis: A protocol of a randomized controlled trial

BACKGROUND

Ankylosing spondylitis is a recurrent autoimmune disease, which has a high disability rate and seriously affects patients' daily life. Conventional treatment cannot effectively solve the clinical problems of patients, and long-term medication is accompanied by adverse reactions. The evidence shows that warming needle moxibustion has advantages in the treatment of ankylosing spondylitis, but there is still a lack of clinical studies on warm acupuncture alone and long-term follow-up.

METHODS

This is a prospective randomized controlled trial to study the efficacy and safety of needle warming through moxibustion in the treatment of ankylosing spondylitis. It was approved by the Ethics Committee of Clinical Research of our hospital. Patients were randomly assigned to an observation group or a control group. The patients were followed up for 6 months after 30 days of treatment. Observation indicators include; activity index, functional ability, Bath Ankylosing Spondylitis Metrology Index, inflammatory indicators, adverse reactions, and so on. Finally, SPASS 22.0 software is used for statistical analysis of the data.

DISCUSSION

This study will evaluate the clinical efficacy of warming needle moxibustion in the treatment of ankylosing spondylitis. The results of this study will provide a reference basis for the clinical use of warm needle moxibustion in the treatment of ankylosing spondylitis.

TRIAL REGISTRATION

OSF Registration number: DOI 10.17605/OSF.IO/GWPX3.

Single nucleotide polymorphisms of TRAF2 and TRAF5 gene in ankylosing spondylitis: a case-control study

Objective To investigate the role of eight locus polymorphisms of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TRAF5 gene and their interaction in the susceptibility to ankylosing spondylitis (AS) in Chinese Han population. Methods Eight single nucleotide polymorphisms (SNPs) of TRAF2 (rs3750511, rs10781522, rs17250673, rs59471504) and TRAF5 (rs6540679, rs12569232, rs4951523, rs7514863) gene were genotyped in 673 AS patients and 687 controls. Results The SNPs of TRAF2 and TRAF5 do not indicate a correlation with the susceptibility of AS in Chinese Han population. Genotype frequencies of rs3750511 were statistically significant in females between patients and controls. The allele frequencies of rs10781522 and genotype frequencies of rs3750511 were statistically significant between groups of different diseases activity. One three-locus model, TRAF2 (rs10781522, rs17250673) and TRAF5 (rs12569232), had a maximum testing accuracy of 52.67% and a maximum cross-validation consistency (10/10) that was significant at the level of P = 0.0001, after determined empirically by permutation testing. As to environmental variables, only marginal association was found between sleep quality and AS susceptibility. Conclusion TRAF2 rs3750511 polymorphism may be associated with the susceptibility and severity of AS. Besides, the interaction of TRAF2 and TRAF5 genes may be associated with AS susceptibility, but many open questions remain.

Effects of traditional qigong exercise on ankylosing spondylitis: a protocol for systematic reviews and meta-analysis

INTRODUCTION

Ankylosing spondylitis (AS) is a recurrent autoimmune disease that is associated with a high disability rate, which has a profound negative impact on daily life. It has been clinically reported that traditional qigong exercise has certain therapeutic advantages in treating AS; however, this postulation is not evidence-based. Therefore, this study will aim at systematically appraising the validity and safety of traditional qigong exercise in treating AS.

METHODS AND ANALYSIS

We searched the English (PubMed, Embase, Web of Science and the Cochrane Library) and Chinese databases (China National Knowledge Infrastructure, Wan fang, VIP and Chinese biomedical database) for relevant information. Additionally, the Baidu Academic and Google Academic databases were manually searched to mine relevant information. Randomised controlled clinical trials of traditional qigong exercise in treating AS were searched from the establishment of the database to September 2020. Quality articles were extracted and independently evaluated by two researchers before inclusion in this study. Meta-analysis of the included articles was performed using the RevMan V.5.3 software.

ETHICS AND DISSEMINATION

This study will not involve primary data collection, and formal ethics approval will, therefore, not be required. We aim to publish this systematic review in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

CRD42020207057.

Intestinal and enthesis innate immunity in early axial spondyloarthropathy

Axial SpA (axSpA), encompassing AS, is a multifactorial disease that localizes to sites of high spinal biomechanical stress. Much has been written on T cells and adaptive immunity in axSpA, which is understandable given the very strong HLA-B27 disease association. Extra-axial disease characteristically involves the anterior uveal tract, aortic root, lung apex and terminal ileum. Under recent classification, axSpA is classified as an intermediate between autoimmunity and autoinflammatory disease, with the latter term being synonymous with innate immune dysregulation. The purpose of this review is to evaluate the ‘danger signals’ from both the exogenous intestinal microbiotal adjuvants or pathogen-associated molecular patterns that access the circulation and endogenously derived damaged self-tissue or damage-associated molecular patterns derived from entheses and other sites of high biomechanical stress or damage that may serve as key drivers of axSpA onset, evolution, disease flares and eventual outcomes.

Lack of Associations between Endoplasmic Reticulum Aminopeptidase 2 Gene Polymorphisms and Ankylosing Spondylitis: A Meta-analysis with Trial Sequential Analysis

Background: Endoplasmic reticulum aminopeptidase 2 (ERAP2) gene is reported to be associated with inflammation-related diseases. Several studies have investigated the associations of ERAP2 gene polymorphisms and susceptibility to ankylosing spondylitis (AS). However, the findings of those studies were inconsistent. The aim of this study was to elucidate the associations by a meta-analysis with trial sequential analysis (TSA).Methods: Online databases of PubMed, Web of Science, EMBASE, Cochrane Library, Wanfang, and CNKI were searched to identify eligible studies on the associations of ERAP2 gene polymorphisms and AS. Study quality was judged based on the Newcastle-Ottawa scale (NOS). Strengths of associations were presented by P-value, odds ratios (ORs), and 95% confidence intervals (95%CIs). TSA was employed to evaluate the information size and statistical power.Results: A total of six studies encompassing 2774 AS patients and 4119 disease-free controls were eligible for this meta-analysis. Five studies reported rs2248374 polymorphism and three studies reported rs2549782 polymorphism. The pooled data suggested that the two polymorphisms were not significantly associated with AS susceptibility: rs2248374, A vs. G, OR = 0.94, 95%CI 0.86-1.02, P = .14; rs2549782, T vs. G, OR = 1.03, 95%CI 0.95-1.12, P = .45. TSA indicated that the sample sizes appeared to be inadequate to obtain a positive outcome.Conclusion: The present findings of this study do not support any evidence on the associations of rs2248374 and rs2549782 polymorphisms in the ERAP2 gene and susceptibility to AS. Additional well-designed and large-sample studies in diverse ethnicities are encouraged to validate the current findings.

SNP-adjacent super enhancer network mediates enhanced osteogenic differentiation of MSCs in ankylosing spondylitis

Ankylosing spondylitis (AS) is a rheumatic disease with pathological osteogenesis that causes bony ankylosis and even deformity over time. Mesenchymal stem cells (MSCs) are multipotent stem cells that are the main source of osteoblasts. We previously demonstrated that enhanced osteogenic differentiation of MSCs from AS patients (ASMSCs) is related to pathological osteogenesis in AS. However, the more concrete mechanism needs further exploration. Super enhancers (SEs) are dense clusters of stitched enhancers that control cell identity determination and disease development. Single-nucleotide polymorphisms (SNPs) regulate the formation and interaction of SEs and denote genes accounting for AS susceptibility. Via integrative analysis of multiomic data, including histone 3 lysine 27 acetylation (H3K27ac), chromatin immunoprecipitation sequencing (ChIP-seq), SNPs and RNA sequencing (RNA-seq) data, we discovered a transcription network mediated by AS SNP-adjacent SEs (SASEs) in ASMSCs and identified key genes, such as Toll-like receptor 4 (TLR4), interleukin 18 receptor 1 (IL18R1), insulin-like growth factor binding protein 4 (IGFBP4), transportin 1 (TNPO1) and proprotein convertase subtilisin/kexin type 5 (PCSK5), which are pivotal in osteogenesis and AS pathogenesis. The SASE-regulated network modulates the enhanced osteogenic differentiation of ASMSCs by synergistically activating the PI3K-Akt, NF-kappaB and Hippo signaling pathways. Our results emphasize the crucial role of the SASE-regulated network in pathological osteogenesis in AS, and the preferential inhibition of ASMSC osteogenic differentiation by JQ1 indicates that SEs may be attractive targets in future treatment for new bone formation in AS.

Which factors are associated with bone marrow oedema suspicious of axial spondyloarthritis as detected by MRI in the sacroiliac joints and the spine in the general population?

Objective

Identify factors associated with presence and extension of spinal and sacroiliac joints (SIJ)–MRI lesions suggestive of axial spondyloarthritis (axSpA) in a population-based cohort (Study of Health in Pomerania) aged <45 years.

Methods

Spinal (sagittal T1/T2) and SIJ (semicoronal STIR sequences) MRIs were evaluated by two trained blinded readers. The presence (yes/no) and extension (Berlin MRI Score) of bone marrow oedema (BME) were captured. Degenerative spinal lesions were excluded and discrepancies resolved by consensus. Cross-sectional associations between clinical factors and presence/extension of BME were analysed by logistic/negative binomial regression. Record linkage of claims data was applied to identify participants with axSpA.

Results

MRIs of 793 volunteers were evaluated. The presence of SIJ–BME (odds ratio) was strongly associated delivery during the last year (4.47, 1.49–13.41). For SIJ–BME extension, associations (incidence rate ratios, 95% CI) were found for delivery ((during last year) 4.52, 1.48–13.84), human leucocyte antigen (HLA)-B27+ (2.32, 1.30–4.14), body mass index (25–30 vs <25 kg/m²; 1.86 (1.19–2.89)) and back pain ((last 3 months) 1.55, 1.04–2.31), while for spinal BME, associations were found for age per decade (1.46, 1.13–1.90) and physically demanding work (1.46, 1.06–2.00). Record linkage was available for 694 (87.5%) participants and 9/694 (1.3%) had a record of axSpA (ICD M45.09).

Conclusion

These population-based data support the hypothesis of mechanic strain contributing to BME in the general population aged <45 years and the role of HLA-B27+ as a severity rather than a susceptibility factor for SIJ–BME.

Ankylosis progressive homolog upregulation inhibits cell viability and mineralization during fibroblast ossification by regulating the Wnt/β‑catenin signaling pathway

Ankylosis progressive homolog (ANKH) is associated with fibroblast ossification in ankylosing spondylitis (AS). As the human ANKH gene is poorly characterized relative to its murine counterpart, the aim of the present study was to examine ANKH expression in ligament tissue isolated from patients with AS and the role played by this gene in AS‑associated fibroblast ossification. Fibroblasts were isolated from ligament tissue collected from patients with AS and ligament tissue from individuals with spinal cord fractures, then cultured. Fibroblasts from patients with AS were subsequently transfected with an ANKH overexpression vector, while those collected from individuals with spinal cord fractures were transfected with small interfering RNA specific for ANKH. Cell viability, apoptosis and mineralization were analyzed using MTT assays, flow cytometry and Alizarin Red staining, respectively. Furthermore, ANKH mRNA and protein expression levels were analyzed using reverse transcription‑quantitative PCR and western blotting analysis, respectively. The expression levels of osteogenesis markers, including alkaline phosphatase, osteocalcin, Runt‑related transcription factor 2, c‑Myc, as well as the β‑catenin signaling protein, were also determined using western blotting. The results of the present study revealed that ANKH protein expression levels were downregulated in AS total ligament tissue extract, compared with spinal fracture ligament. Moreover, the fibroblasts derived from patients with AS exhibited an increased viability and reduced apoptosis rates, compared with the fibroblasts from patients with spinal fracture. Notably, ANKH overexpression inhibited viability, mineralization and ossification, increased the phosphorylation of β‑catenin and downregulated β‑catenin and c‑Myc protein expression levels in fibroblasts from patients with AS. In addition, ANKH overexpression increased the ratio of p‑β‑catenin/β‑catenin in fibroblasts from patients with AS. By contrast, ANKH silencing in fibroblasts from patients with spinal fracture resulted in the opposite effect. In conclusion, the findings of the present study suggested that ANKH may inhibit fibroblast viability, mineralization and ossification, possibly by regulating the Wnt/β‑catenin signaling pathway.

BMP2 variants in the risk of ankylosing spondylitis

The purpose of the study was to explore the genetic effects of bone morphogenetic protein (BMP2) polymorphisms on the susceptibility to ankylosing spondylitis (AS) in Chinese Han population. The case-control study included 120 AS cases and 110 healthy controls. Hardy-Weinberg equilibrium test was performed in control group. BMP2 rs235768 and rs3178250 polymorphisms were analyzed by polymerase chain reaction and direct sequencing. Additionally, the χ²  test was used to estimate association strength between BMP2 genetic polymorphisms and AS susceptibility, and the results were assessed via odds ratio (OR) with the corresponding 95% confidence interval (95%CI). Results adjustment was performed using logistic regression analysis. AA, AT, TT genotype and A, T allele frequencies of BMP2 rs235768 polymorphism presented no significant differences between case and control groups (P > .05 for all). TC genotype of rs3178250 polymorphism showed significantly higher in case group than that in control group (P = .048). After adjusting, TC genotype was a risk factor for AS (OR = 2.095; 95%CI = 1.086-4.038; P = .027). BMP2 rs3178250 polymorphism may increase individual susceptibility to AS in Chinese Han population.

lncRNA MEG3 Suppresses the Progression of Ankylosis Spondylitis by Regulating the Let-7i/SOST Axis

Ankylosis spondylitis (AS) is a disease mainly characterized by sacroiliac joint and spinal attachment point inflammation. Long non-coding RNA (lncRNA) plays a key role in the progression of many diseases. However, few studies have been conducted on the function of lncRNA maternally expressed gene 3 (MEG3) in AS. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the relative levels of MEG3, microRNA let-7i, sclerostin (SOST), and inflammatory cytokines. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and biotin-labeled RNA pull-down assay were used to confirm the interaction between MEG3 and let-7i or let-7i and SOST. In addition, western blot (WB) analysis was performed to detect the protein levels of osteogenesis markers and SOST. The expression levels of MEG3 and SOST were decreased and let-7i was increased in AS patients. MEG3 could interact with let-7i in AS fibroblasts, and let-7i overexpression reversed the suppressive effect of MEG3 upregulation on the inflammation and bone formation of AS. Additionally, let-7i could target SOST, and SOST silencing reversed the inhibitory effect of let-7i inhibitor or MEG3 overexpression on the inflammation and bone formation of AS. Furthermore, SOST expression was positively regulated by MEG3, while was negatively regulated by let-7i. Our results revealed that lncRNA MEG3 promoted SOST expression to restrain the progression of AS by sponging let-7i, which provided a treatment target for AS.

Proteomic analysis of serum-derived extracellular vesicles in ankylosing spondylitis patients

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease, whose pathogenesis is still unclear. Many studies show the proteins in extracellular vesicle (EVs) would change regularly in many diseases. The study aims to explore the proteins contents of serum-derived EVs in AS patients.

METHODS

EVs were separated by ExoQuick^TM kit. The protein profiles of AS patients and healthy subjects were analyzed by Label-free-liquid chromatography mass spectrometry (LC-MS/MS) technology. Enzyme-linked immunosorbent assay (ELISA) was used to verify the levels of the differently expressed proteins. Receiver operation characteristic (ROC) curves and bioinformatic analysis were conducted.

RESULTS

Six hundred and ten serum-derived EVs proteins from AS patients were detected. Seventy-three diferentially expressed proteins were found in AS group, compared with healthy subjects. Of these, 31 proteins were up-regulated in AS group, while 42 proteins were down-regulated. ELISA result showed that EVs-derived serum amyloid A-1 (SAA1) was higher in AS group, which was consistent with the Label-free-LC-MS/MS data. ROC curves result revealed that the area under curve (AUC) value of EVs-derived SAA1 for AS was 0.768 (0.652-0.885). Bioinformatic analysis revealed that the differently expressed proteins in AS group were significantly involved in "complement and coagulation cascades", "staphylococcus aureus infection", "systemic lupus erythematosus" and "PI3K-Akt signaling pathway".

CONCLUSIONS

The protein profiles of serum-derived EVs in AS patients and healthy subjects were different. EVs-derived SAA1 may be a potential biomarkes of AS. The function analysis indicated that the differentially expressed proteins may potentially participate in immune response.