Understanding the Pathogenesis of Spondyloarthritis

Arthritis related to parasitic infections

Various parasitic infections can manifest with symptoms resembling inflammatory rheumatic diseases. Parasitic arthritis is uncommon, and the literature concerning rheumatic manifestations of specific parasitic infections tends to be limited to case reports. Despite its rarity, parasitic infections should always be included in the differential diagnosis of rheumatic presentations when there is a history of risk factors, particularly in patients from endemic regions and in atypical rheumatic presentations. Specific treatment of the parasitic infection often leads to significant improvement or resolution of symptoms. This account discusses various parasites that have been reported to be associated with arthritis and other related musculoskeletal manifestations.

The causal impact of genetically predicted inflammatory bowel disease on extraintestinal manifestations: a mendelian randomization study

BACKGROUND

Extraintestinal manifestations (EIMs) significantly affect the life quality of people with inflammatory bowel disease (IBD) and are crucial factors impacting occurrence rates and mortality among IBD patients. This study performed a Mendelian randomization (MR) analysis to investigate the causal relationships between genetically predicted IBD and the development of EIMs, including erythema nodosum (EN), episcleritis, scleritis, uveitis, primary sclerosing cholangitis (PSC), and spondyloarthritis. To further investigate differences between subtypes, separate analyses were conducted for ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

The study was conducted based on genome-wide association studies (GWAS) data. We carefully selected SNPs associated with both exposure and outcome by comparing and integrating data from GWAS and relevant literature, and prioritizing studies with large sample sizes, high quality, and as much population homogeneity as possible. The SNPs associated with IBD, UC and CD were extracted from the International Inflammatory Bowel Disease Genetics Consortium. And the SNPs associated with EIMs were extracted from the UK Biobank, the International PSC Study Group and the FinnGen study. A series of quality control steps were taken in our analysis to select eligible instrumental SNPs which were strongly associated with exposure. The causal effects were estimated using a primary analysis that employed inverse-variance weighting (IVW) and complementary analysis that utilized MR-Egger weighted by the median. A sensitivity analysis was conducted using the Cochran Q statistic, a funnel plot, the MR-Egger intercept, and a leave-one-out approach. Reverse causality analysis was also performed to ensure the robustness of the findings. Furthermore, a fixed-effects meta-analysis was employed to combine MR outcomes from various data origins, bolstering the strength and dependability of our findings.

RESULTS

Our findings indicated that genetically predicted IBD had a robust causal relationship with an increased risk of specific conditions, including EN (OR, 1.20; 95% CI, 1.09-1.32; p < 0.01), uveitis (OR, 1.15; 95% CI, 1.11-1.20; p < 0.01), PSC (OR, 1.21; 95% CI, 1.13-1.28; p < 0.01), and spondyloarthritis (OR, 1.19; 95% CI, 1.14-1.23; p < 0.01). In subgroup analyses, the causal effects of both UC and CD on EN, uveitis, PSC, and spondyloarthritis were also significant and robust. Additionally, no significant evidence of causality was observed between genetically predicted IBD, UC, and CD, and the occurrence of both episcleritis and scleritis. The results of reverse causality analysis indicated a robust causal association between genetically predicted PSC and the elevated risk of IBD (OR, 1.21; 95% CI, 1.15-1.29; p < 0.01), UC (OR, 1.27; 95% CI, 1.17-1.37; p < 0.01), and CD (OR, 1.10; 95% CI, 1.02-1.20; p < 0.01). Additionally, spondyloarthritis had a causal relationship with an increased risk of both IBD (OR, 1.03; 95% CI, 1.01-1.06; p < 0.01) and UC (OR, 1.05; 95% CI, 1.02-1.08; p < 0.01).

New thoughts on the gut-immune axis of arthritis

Arthritis is associated with varying degrees of intestinal inflammation and microbiota dysbiosis, leading to the 'gut-joint axis hypothesis' in which intestinal and joint inflammation are suggested to be interconnected through immune-microbiota interactions. While clinical observations support this, causality remains uncertain. Rodent models have provided insights into potential mechanisms by uncovering microbial influences and immune pathways that either connect or uncouple gut and joint inflammation. Based on recent findings, we propose the 'immune hypersensitivity hypothesis' whereby central immune hyper-reactivity can independently drive joint inflammation via local sterile triggers, and gut inflammation via microbial triggers. We argue that this suggests a more nuanced role of the microbiota in arthritis pathogenesis that varies according to the predominant immune mechanisms in disease subtypes. We explore gut-immune interactions in arthritis, highlight ongoing challenges, and propose future research directions.

Dysregulation of amino acid and lipid metabolism in patients with spondyloarthritis

OBJECTIVE

To conduct a metabolomics analysis in patients with spondyloarthritis (SpA) and compare results with those from healthy controls. The overall goal was to identify small-molecule substances that may have potential pathogenic and diagnostic significance in SpA.

METHODS

This was an observational, cross-sectional, single-centre study that included patients with axial (ankylosing spondylitis [AS]), peripheral (psoriatic arthritis [PsA]) and healthy controls.

RESULTS

The study included 50 patients with AS, 50 patients with PsA, and 164 controls. When compared with healthy controls, patients with SpA showed significant differences in 35 metabolites, primarily associated with amino acid and lipid metabolism. However, only two differences were found between the AS and PsA cohorts (glucose and glycerol).

CONCLUSIONS

Our data suggest that patients with SpA exhibit significant disruptions in amino acid and lipid metabolism. The large number of identified metabolites offers promising opportunities, both for discovering new SpA biomarkers and for gaining a deeper understanding of the pathophysiology of these chronic inflammatory diseases.

Defining a genetic background for bamboo spine and axial spondyloarthritis

OBJECTIVE

Bamboo spine is the most severe complication of axial spondyloarthritis (AxSpA). This study aims to address whether haplotypes of endoplasmic reticulum aminopeptidase (ERAP)1 and ERAP2 single nucleotide polymorphisms (SNPs), previously associated with AxSpA, are associated with the development of bamboo spine in an AxSpA cohort.

METHODS

The study included 192 patients with AxSpA followed in MARS (MARmara Spondyloarthritis) clinic and fulfilling the modified New York criteria. ERAP1 and ERAP2 polymorphisms were determined by real-time PCR on genomic DNA using the TaqMan SNP Genotyping Assay for SNPs rs72773968, rs3734016, rs26653, rs26618, rs27895, rs2287987, rs30187, rs10050860, rs17482078, rs27044, rs2549782, rs2248374. The HLA-B genotypes were assessed using the LABTypeTM SSO method.

RESULTS

Male gender (P<0.001) and HLA-B27 positivity (P<0.05) were associated with an increased risk of developing a bamboo spine, and peripheral arthritis was significantly less prevalent in AxSpA patients with a bamboo spine (P<0.05). Of the ten ERAP1 haplotypes, haplotype 3 was significantly more prevalent in AxSpA patients with bamboo spine adjusted for HLA-B27 status (P<0.05). Haplotype 3 and -6 were significantly more prevalent exclusively in HLA-B27 (+) patients (P<0.05). Allele frequencies and genotype distributions of single ERAP1 SNPs alone were not significantly different between AxSpA patients with and without bamboo spines. There was no association between bamboo spine development and ERAP2 SNPs.

CONCLUSIONS

Our results indicate that HLA-B27 positivity, ERAP1 haplotype 3 and -6, and being male confer a significant risk for developing bamboo spine. Whether the association of haplotype 3 and -6 with bamboo spine is confined only to our Turkish patient cohort may deserve attention in other ethnicities.

Ankylosing spondylitis: From pathogenesis to therapy

Ankylosing spondylitis (AS) is an autoimmune rheumatic disease that primarily affects the axial joints, with its etiology complex and still not fully understood. The unknown pathogenesis of AS limits the development of treatment strategies, so keeping up-to-date with the current research on AS can help in searching for potential therapeutic targets. In addition to the classic HLA-B27 genetic susceptibility and Th17-related inflammatory signals, increasing research is focusing on the influence of autoantigen-centered autoimmune responses and bone stromal cells on the onset of AS. Autoantigens derived from gut microbiota and preferential TCR both exacerbate the autoimmune response in patients with AS. Furthermore, dysregulated bone metabolism also promotes pathological new bone formation in AS. Current treatments approved for AS almost focus on the management of inflammation with inconsistent treatment results due to the heterogeneity of patients. In this review, we systematically summarized various pathogenesis and management of AS, meanwhile discussed the underlying risk factors and potential therapeutic targets.

Obesity and Chronic Inflammation: Implications for Rheumatoid Arthritis, Spondyloarthritis, and Ulcerative Colitis

BACKGROUND

Immune-mediated inflammatory diseases (IMIDs) are a group of chronic conditions characterized by dysregulated immune responses and persistent inflammation. Rheumatoid arthritis (RA), spondyloarthritis (SpA), and ulcerative colitis (UC) exemplify prominent IMIDs, each presenting unique challenges for their management, that impact patient's quality of life (QoL). Obesity, marked by persistent low-grade inflammation, influences the progression, response to treatment, and clinical management of patients with RA, SpA, and UC. Besides, the emerging role of sarcopenic obesity, a special subtype of obesity with malnutrition, should be considered in the definition of the appropriated therapeutic interventions.

METHODS

This narrative literature review summarizes recent evidence on the interplay between obesity-induced inflammation and IMIDs.

RESULTS

Obesity contributes to elevated levels of proinflammatory cytokines, influencing the inflammatory pathways common to IMIDs. White adipose tissue, acting as an endocrine organ, produces cytokines like TNF-α and IL-6, fueling chronic inflammation. The dysregulation of adipokines, such as leptin and adiponectin, further complicates this interplay, impacting immune responses and metabolic processes.

CONCLUSIONS

Understanding the cross-talk between inflammatory pathways in obesity and IMIDs can provide insight into potential targets for intervention. This includes lifestyle modifications aimed to regulate weight gain, paving the way for comprehensive strategies to manage IMIDs in the context of obesity.

A small-scale preliminary study utilizing mass cytometry to distinguish two forms of arthritis

OBJECTIVES

Spondyloarthritis (SpA) and rheumatoid arthritis (RA) are hallmarked by immune cell infiltration in synovial joints. Although, in general, different sites are affected, misclassification or delayed diagnosis due to overlapping clinical manifestations is not uncommon. Here, we investigated the diagnostic potential of mass cytometry (MC) in early peripheral SpA (pSpA) and RA patients in a small pilot study.

METHODS

Peripheral blood and synovial fluid mononuclear cells (PBMC and SFMC) of 4 pSpA, 7 RA, and 1 undifferentiated arthritis (UA) patient(s) were evaluated using a 37-marker MC panel. Data were analyzed through Visualyte services, including dimension reduction, clustering, and Cytofast workflow.

RESULTS

PBMC data indicated naive CD4 T cell, B cell, and monocyte subsets to be differentially present in RA as compared with SpA. CD4 + Tem cell and NK cell subsets appeared more prominently present in pSpA SFMC. Merged PBMC and SFMC data showed overlapping immune profiles of an UA patient with pSpA patients. These results were in accordance with the formal clinical pSpA diagnosis the UA patient received after this study.

CONCLUSIONS

Utilizing MC, several differences in immune cell composition in both SFMC and PBMC between RA and pSpA patients were observed. Combining PBMC and SFMC data in an unsupervised analysis resulted in the correct classification of the UA patient as pSpA patient prior to formal clinical pSpA diagnosis. This pilot study provides an example of how deep phenotyping with MC aids in differentiating arthritis patients and offers a rationale to further explore these findings.

KEY POINTS

•Due to overlapping symptoms and the absence of disease-specific biomarkers, the clinical diagnosis of peripheral spondyloarthritis (pSpA) and rheumatoid arthritis (RA) can be difficult. •Visualizing immune cell profiles of peripheral blood (PB) and synovial fluid (SF) by mass cytometry (MC) suggests differences in immune cell composition between pSpA and RA patients. •Based on immune profiles of combined PB and SF data, we could correctly predict the formal clinical pSpA diagnosis of an undifferentiated arthritis (UA) patient received later. •This pilot study gives an example of how MC might contribute to faster clinical diagnosis of pSpA patients in the absence of biomarkers.

Incremental Cardiovascular Risk of Menopause in Women with Psoriasis, Psoriatic Arthritis or Spondyloarthritis?

PURPOSE OF THE REVIEW

This narrative review aims to discuss the most recent studies regarding the risk of cardiovascular disease (CVD) in women with psoriasis, psoriatic arthritis (PsA) and spondyloarthritis (SpA). In addition, the potential of menopause to modulate/increase CVD risk in women with these diseases will also be explored. It is of major interest to gain more understanding into this topic because it can have meaningful implications for screening and treatment of CVD risk in these women.

RECENT FINDINGS

Literature shows that psoriasis, PsA, SpA and menopause itself cause higher CVD risks and higher CVD prevalence. This is predominantly explained by the increase of chronic systemic inflammation. No existing literature conclusively demonstrates or studies specifically whether the menopause amplifies this effect caused by psoriasis, PsA, or SpA.

CONCLUSION

Differences in pathophysiology of psoriasis, SpA and PsA versus the menopausal transition could suggest that menopause may increase the risk of CVD. However, the hypothesis that menopause represents an additional CV risk factor in women with psoriasis, PsA and SpA still needs to be thoroughly investigated and more clinical studies are required for further understanding and conclusions.

Immunologic derangement caused by intestinal dysbiosis and stress is the intrinsic basis of reactive arthritis

Reactive arthritis (ReA) is defined as arthritis resulting from infections in other body parts, such as the gastrointestinal and urogenital tracts. The primary clinical manifestations involve acute-onset and self-limiting asymmetric large joint inflammation in the lower limbs. Although bacterial or chlamydia infections have long been recognized as playing a pivotal role in its pathogenesis, recent studies suggest that antibiotic treatment may perpetuate rather than eradicate chlamydia within the host, indicating an involvement of other mechanisms in Reactive arthritis. Reactive arthritis is currently believed to be associated with infection, genetic marker (HLA-B27), and immunologic derangement. As an autoimmune disease, increasing attention has been given to understanding the role of the immune system in Reactive arthritis. This review focuses on elucidating how the immune system mediates reactive arthritis and explores the roles of intestinal dysbiosis-induced immune disorders and stress-related factors in autoimmune diseases, providing novel insights into understanding reactive arthritis.

TNFα Inhibitors Versus Newer Therapies in Spondyloarthritis: Where do we Stand Today?

The spondyloarthritides (SpA) are a group of chronic inflammatory diseases that affect the axial skeleton (ax-SpA), peripheral joints and entheses (p-SpA) and are expressed with several clinical phenotypes such as psoriasis, psoriatic arthritis (PsA), inflammatory bowel disease (IBD), and uveitis. The pathogenesis of SpA involves the pivotal role of tumour necrosis factor alpha (TNFα) and the interleukins (IL) IL-17/IL-23. Their distribution and hierarchy in the affected organs and tissues is differently expressed in SpA. TNFα is expressed in all tissues and organs, while IL-17 and IL-12/IL-23 is lacking from the gut and the axial skeleton respectively. This knowledge is a dilemma for physicians when they must choose a biological therapy. Nowadays, the armamentarium of SpA treatment has been expanded comprising biological therapies such as TNFα inhibitors (TNFαi), IL-17 inhibitors (IL-17i), IL-12/IL-23 inhibitors (IL-12/IL-23i), as well as the Janus Kinase inhibitors (JAKi). Several studies have shown that IL-12/IL-23i are very effective to treat psoriasis, PsA and IBD, but are ineffective in treating ax-SpA. IL-17i are very effective in patients with ax-SpA, psoriasis and PsA, but seem ineffective in IBD. Finally, TNFαi have shown to be effective in all SpA phenotypes with an acceptable toxicity profile. On the other hand, JAKi are also effective in almost all SpA phenotypes, but caution is required for elderly patients who may develop Herpes-Zoster infection, thromboembolic events and malignancies. However, the treatment of SpA is individualised according to the clinical phenotype and after shared decision between patients and physicians.

Elevated Calprotectin Levels Reveal Loss of Vascular Pattern and Atrophy of Villi in Ileum by Digital Chromoendoscopy and Magnification Colonoscopy in Patients with Spondyloarthritis Without Having Inflammatory Bowel Disease

OBJECTIVE

This study aimed to establish a correlation between fecal calprotectin levels (FC) and intestinal inflammation in patients with spondyloarthritis without inflammatory bowel disease.

METHODS

A total of 180 SpA patients were included in the study of them 20.6% required Digital chromoendoscopy (DCE). FC, C-reactive protein (CRP), HLA-B*27 and clinical indices were assessed.

RESULTS

Positive fecal calprotectin (PFC) and high fecal calprotectin (HFC) levels were observed in 27.0% and 16.0% of patients, respectively. HFC correlated with a Bath Ankylosing Spondylitis Functional Index (BASFI) score > 4.0 (p = 0.036) and a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score > 4.0 (p = 0.047). Loss of vascular pattern in the ileum (LVPI) was observed in approximately 70.0% of patients (p = 0.005), which was associated with PFC and abdominal bloating (p = 0.020). LVPI was also linked to microscopic inflammation (p = 0.012) and PFC with abdominal pain (p = 0.007). HFC was significantly associated with alterations in the ileal mucosa (p = 0.009) and LVPI (p = 0.001). Additionally, HFC and diarrhea were associated with LVPI in 27.3% of patients (p = 0.037) and with erosions in the ileum (p = 0.031). Chronic ileal inflammation correlated with HFC (p = 0.015), ASDAS-CRP > 2.1 (p = 0.09), LVPI (p = 0.001), and villous atrophy (p = 0.014). Factorial analysis of mixed data (FAMD) identified significant associations between micro/macroscopic changes in chronic inflammation and HFC (CC = 0.837); increased levels of CRP and microscopic acute inflammation (CC = 0.792); and clinical activity scores of ASDAS-CRP and BASDAI (CC = 0.914).

CONLUSIONS

FC levels were significantly elevated in patients with SpA, particularly those with LVPI, suggesting their potential as a valuable biomarker for managing SpA when joint manifestations coincide with ileal villous atrophy. This indicates a shared immune pathway linked to chronic gut damage.

An Actual Insight into the Pathogenic Pathways of Ankylosing Spondylitis

Spondyloarthritis refers to a broad group of conditions that include ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and enteropathic arthritis associated with Crohn's disease or ulcerative colitis. They have been classified by the ASAS group (ASsessment in Ankylosing Spondylitis) into axial spondyloarthritis and peripheral spondyloarthritis. Common features include the absence of autoantibodies, genetic predisposition, and clinical aspects such as axial joint involvement, peripheral manifestations, and extra-articular involvement. However, the pathogenic mechanisms remain complex and incompletely elucidated, despite the fact that the specialized literature has described several pathways that act in synergy: genetic predisposition, environmental factors (infections and mechanical stress), or innate and acquired immune mechanisms. Finally, an inflammatory response is triggered by the recruitment of a large number of inflammatory cells and the release of innate cytokines in the affected areas: joints or periarticular or extraarticular tissues. The current article aims to update and systematize the knowledge accumulated so far on this topic, focusing on the mechanisms that have been involved in the onset, progression, and severity of ankylosing spondylitis.

Is vitamin D associated with disease activity in patients with axial or peripheral spondyloarthritis? A real-life study

Vitamin D plays important role in inflammatory rheumatic diseases, which in turn rose an interest for investigating association of its deficiency with disease activity. In this research we aimed to evaluate this matter in the context of spondyloarthritis (SpA), together with treatment modalities and bone density in people diagnosed with axial or peripheral SpA in real-life setting. In our study we enrolled 99 patients with diagnosis of SpA treated at the tertiary level rheumatology department. Serum 25(OH)D levels, treatment modality (NSAIR or DMARDs), disease activity, tobacco smoking habits, mineral density of bone, supplementation and seasonal variations were assessed. We used standardized questionnaires such as ASDAS-CRP, BASFI and joint count, among many others, to evaluate some of the mentioned parameters. Sixty-five percent of patients had vitamin D deficiency. We found marginaly higher activity of disease in subjects with low vitamin D. In cases of peripheral SpA, there was a significant association of higher number of swollen joints and lower vitamin D levels. Additionally, the significant correlation was seen between normal serum vitamin D and supplementation. In our real-life study of patients with SpA we found a significant percentage of vitamin D deficit, with a tendency of slightly higher disease activity in those patients.In order to clarify the impact of the vitamin on disease activity in SpA and the supplementation recommendations for patients with these conditions, the conduction of further studies is required.

The Effect of Therapeutic Exercise and Local Cryotherapy on Lower Limb Enthesitis in Non-Radiographic Axial Spondyloarthritis: A Case Report

BACKGROUND

Enthesitis is a common feature of spondyloarthritis and can severely impair the patient's quality of life. International guidelines recommend multidisciplinary management of this condition, combining physical and pharmacological interventions. In this case report, we demonstrate clinical and ultrasonographic improvements by prescribing local cryotherapy and therapeutic exercise alone in an adult woman with non-radiographic axial SpA (nRX-AxSpA) complaining of heel enthesitis.

METHODOLOGY

A personalized program was prescribed that focused on reducing pain, joint stiffness, and muscle tightness, improving strength and endurance. Pain, function, and degree of disability were assessed using the Numerical Rating Scale, the Victorian Institute of Sport Assessment-Achilles, the single-leg heel lift test, and the Foot Function Index. In addition, lower limb muscle strength was measured using a dynamometer and enthesitis was assessed ultrasonographically using the Glasgow Ultrasound Enthesitis Score System.

RESULTS

Benefits were evident as early as week 5 and persisted at 3 months on ultrasound assessment. No side effects were reported.

DISCUSSION

To the best of our knowledge, this is the first report of prescribing such a strategy in a patient with nRX-AxSpA. Given the good tolerability, this intervention could be considered in patients with contraindications to pharmacologic approaches.

Carnosic Acid: A Novel Selective Inhibitor of ERAP1 by Direct Binding and Its Modulation of Antigen Processing and Presentation

ERAP1 is an emerging target for a large subclass of severe autoimmune diseases known as "MHC-I-opathy", together with tumor immunity. Nevertheless, effective inhibitors targeting ERAP1 remain a challenge. In this study, a novel food-derived natural product ERAP1-targeting inhibitor, carnosic acid, was identified, and to our knowledge, it is one of the best active compounds among the highly selective inhibitors targeting the orthosteric site of ERAP1. The results reveal that carnosic acid could bind strongly, like a key to the ERAP1 active site in the biased S1' pocket, which is different from the binding mode of the existing orthosteric site inhibitors. HLA-B27-mediated cell modeling validated that carnosic acid has the activity to reverse the AS-associated cellular phenotype brought on by ERAP1 through inhibition. Our findings provide insights into the design of potent inhibitors against the ERAP1 orthosteric site and the discovery of a key direct target of carnosic acid.

Environmental and Genetic Determinants of Ankylosing Spondylitis

Exposure to heavy metals and lifestyle factors like smoking contribute to the production of free oxygen radicals. This fact, combined with a lowered total antioxidant status, can induce even more damage in the development of ankylosing spondylitis (AS). Despite the fact that some researchers are looking for more genetic factors underlying AS, most studies focus on polymorphisms within the genes encoding the human leukocyte antigen (HLA) system. The biggest challenge is finding the effective treatment of the disease. Genetic factors and the influence of oxidative stress, mineral metabolism disorders, microbiota, and tobacco smoking seem to be of great importance for the development of AS. The data contained in this review constitute valuable information and encourage the initiation and development of research in this area, showing connections between inflammatory disorders leading to the pathogenesis of AS and selected environmental and genetic factors.

Emerging Strategies against Non-Typhoidal Salmonella: From Pathogenesis to Treatment

Even with the intensive efforts by public health programs to control and prevent it, non-typhoidal Salmonella (NTS) infection remains an important public health challenge. It is responsible for approximately 150 million illnesses and 60,000 deaths worldwide annually. NTS infection poses significant risks with high rates of morbidity and mortality, leading to potential short- and long-term complications. There is growing concern among health authorities about the increasing incidence of antimicrobial resistance, with multidrug resistance totaling 22.6% in Europe, highlighting an urgent need for new therapeutic approaches. Our review aims to provide a comprehensive overview of NTS infection. We outline the molecular mechanisms involved in the pathogenesis of NTS infection, as well as the events leading to invasive NTS infection and the subsequent complications associated with it. Given the widespread implications of antimicrobial resistance, our review also presents the global landscape of resistance, including multidrug resistance, and delve into the underlying mechanisms driving this resistance. The rising rates of antibiotic resistance frequently lead to treatment failures, emphasizing the importance of investigating alternative therapeutic options. Therefore, in this review we also explore potential alternative therapies that could offer promising approaches to treating NTS infections.

Association of Endoplasmic Reticulum Aminopeptidase 1 Gene Polymorphism with Susceptibility and Severity of Axial Spondyloarthritis in Egyptian Population: A Single-center Case-Control Study

BACKGROUND

Axial spondyloarthritis (axSpA) is a systemic, progressive, autoimmune disease. Complex interactions between environmental factors and host immune responses are the origin of axSpA. Together with human leukocyte antigen (HLA-B27), endoplasmic reticulum aminopeptidase 1 (ERAP1) gene is a potential non-HLA contributor to axSpA susceptibility.

AIM

This study aimed to identify the role of ERAP1 single-nucleotide polymorphisms (SNPs) (rs30187, rs27044, and rs27037) in susceptibility to and severity of axSpA in Egyptian patients.

METHODS

In this case-control study, we enrolled 120 patients with axSpA and 120 healthy individuals as controls. Real-time polymerase chain reaction was used to identify ERAP1 polymorphisms.

RESULTS

The present study revealed no significant association between ERAP1 SNPs (rs30187, rs27044, and rs27037) and axSpA susceptibility in Egyptian patients. A significant relationship was found only between the ERAP1 SNP rs27037 "GT" genotype and axSpA HLA-B27-positive cases, demonstrating a functional interaction between ERAP1 and HLA-B27-positive cases. Our analysis revealed a significant association between the ERAP1 SNP rs27037 "GT and TT" genotypes and Bath Ankylosing Spondylitis Disease Activity Index, in addition to an association between the ERAP1 SNP rs27037 "TT" genotype and active enthesitis. The ERAP1 SNP rs27044 "GG" genotype was significantly associated with active enthesitis, but not with clinical axial involvement. Finally, we did not observe a significant relationship between HLA-B27 positivity and disease severity in the studied cases.

CONCLUSION

Three SNPs (rs30187, rs27044, and rs27037) in ERAP1 do not confer susceptibility to axSpA in Egyptian patients. This association existed exclusively between the ERAP1 SNP (rs27037) "GT" genotype and axSpA HLA-B27-positive cases.

Screening Tools for Spondyloarthritis in Patients With Psoriasis, Uveitis, and Inflammatory Bowel Disease: A Scoping Review

OBJECTIVE

Extramusculoskeletal manifestations of spondyloarthritis (SpA) may precede the development of articular features. Patients seen in ophthalmology, dermatology, and gastroenterology clinics with uveitis, psoriasis, or inflammatory bowel disease (IBD) may have undiagnosed SpA. We set out to identify and evaluate screening tools for SpA in patients with psoriasis, uveitis, and IBD and determine factors that influence the performance of these instruments.

METHODS

This scoping review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase, and Web of Science were searched from inception to January 2022.

RESULTS

We identified 13 screening tools for psoriatic arthritis, 2 SpA screening tools for uveitis, and 3 SpA screening tools for IBD. All screening tools were patient-oriented questionnaires except for the Dublin Uveitis Evaluation Tool, a physician-applied algorithm. The questionnaires varied in length, scoring method, cutoff score, and spectrum of included SpA features. Average completion time was less than five minutes. Across the three patient populations, the sensitivities and specificities of these screening tools were comparable in the primary validation cohorts. Sensitivities and specificities were generally lower in secondary validation studies, with marked variability among cohorts.

CONCLUSION

Our results highlight the heterogeneity and limitations of existing SpA screening tools. Although these tools show promise for use within a specific target population, none are generalizable to all patients with extramusculoskeletal manifestations at risk of SpA. Future studies should explore the utility of a generic patient-oriented SpA screening tool that can be applied to patients with psoriasis, uveitis, or IBD; is easy to use and comprehend; and captures all clinical domains of SpA.

A short review on deciphering Vyadhikshamatva: insights from HLA-B27-ankylosing spondylitis relation

OBJECTIVES

Various aspects of the concept of Vyadhikshamatva have been thoroughly explored, highlighting its profound significance in resisting disease manifestation, particularly in the context of Ankylosing spondylitis. Investigated the relationship between HLA-B27 and Ankylosing spondylitis (AS) by examining current knowledge and hypotheses Furthermore, efforts were made to portray the influence of prakruti (constitution) and balam (strength) on disease manifestation and progression.

METHODS

Ayurvedic literature along with contemporary research works was analyzed for correlating various aspects like vyadhikshamatva,oja (The final essence of all body elements), and balam along with their influence on the defensive mechanism of the body. A thorough literature search was conducted to explore the strong association between HLA-B27 and AS by examining various hypotheses like the Arthritogenic peptide hypothesis, the Misfolding hypothesis, the Surface Homodimer hypothesis, and the β2 microglobulin hypothesis that attempts to explain the pathogenic role of HLA-B27 in AS. Alongside classical Ayurvedic texts, databases like PubMed and Scopus were searched using keywords such as Immunity, Ankylosing spondylitis, Vyadhikshamatva, HLA-B27, Balam, and Autoimmune disorder with the help of Boolean operators.

RESULTS

The review highlighted the critical role of Vyadhikshamatva in disease prevention, particularly in influencing the manifestation of conditions like AS despite genetic predisposition (HLA-B27). Further, the understanding of the Ayurvedic concepts can clearly explain the conflict that has arisen in the determination of the positive HLAB27 gene in Ankylosing Spondylitis as a definite diagnosing criteria.

CONCLUSIONS

This comprehensive understanding will uplift the need for personalized medicine in disease management. Further research must be needed to understand the interaction between genetic factors (HLAb27), individual constitution, and their vyadikshamatva.

Alarming serum antiprotease levels in axial spondyloarthritis

Objectives

The objective was to assess the serum levels of secretory leukocyte protease inhibitor (SLPI) and elafin in individuals diagnosed with axial spondyloarthritis (AxSpA) and analyze their diagnostic significance and correlation with disease activity.

Patients and methods

The case-controlled, cross-sectional study was conducted between August 2021 and April 2023. Sixty patients diagnosed with AxSpA (n=60) were classified according to imaging results as nonradiographic AxSpA (nr-AxSpA [n=30]; 15 males, 15 females; median age: 30 years; range, 27.6 to 34.1 years) and radiographic AxSpA (r-AxSpA [n=30]; 19 males, 11 females; median age: 33 years; range, 30.6 to 38.1 years), forming two patient groups (the nr-axSpA and r-axSpA groups). A total of 30 age- and sex-matched healthy controls (16 females, 14 males; median age: 33 years; range, 29.2 to 37.1 years) were included. Demographic data, laboratory, and clinical characteristics of the participants were recorded.

Results

There was no significant difference between SLPI and elafin serum levels in the disease groups. SLPI and elafin levels in AxSpA and nr-AxSpA groups were significantly higher compared to the control group (p<0.05). Based on receiver operating characteristic analysis, the diagnostic values of both parameters were found to be significant in the Ax-SpA and nr-AxSpA groups (p<0.05). There was no significant correlation between serum levels of SLPI and elafin and disease activity parameters. Significant positive correlations were found between SLPI and elafin in both the nr-AxSpA (p<0.05, r=0.870) and r-AxSpA (p<0.05, r=0.725) groups.

Conclusion

The levels of SLPI and elafin were found to be significantly elevated in patients with AxSpA, particularly in those with nr-AxSpA, compared to the control group. Therefore, SLPI and elafin can be used as therapeutic biomarkers for the diagnosis of AxSpA and nr-AxSpA. However, no relationship was found with disease activity.

Identification and Clinical Correlation of Circulating MAIT, γδ T, ILC3, and Pre-Inflammatory Mesenchymal Cells in Patients with Rheumatoid Arthritis and Spondyloarthritis

Inflammatory rheumatic diseases (IRDs), such as rheumatoid arthritis (RA) and spondyloarthropathy (SpA), comprise a heterogeneous group of immune-mediated disorders, characterised by the presence of localised and/or systemic inflammation. The limited knowledge of the pathogenesis and the complex mechanisms involved in the induction and maintenance of inflammation in IRDs have impeded the development of reliable biomarkers and the discovery of new therapeutic targets. Although the involvement of heterogeneous cell populations in the pathogenesis of IRDs has been recognised, the characterisation of these cellular subsets in the peripheral blood of patients has not been studied yet. Mass cytometry, allowing the simultaneous detection of more than 120 different parameters in single-cell resolution, will enable the identification of circulating cell subpopulations that might play a pivotal role in IRDs pathophysiology and their potential use as therapeutic targets.

Dysbiosis in Inflammatory Bowel Disease and Spondyloarthritis: Still a Long Way to Go?

The association between Inflammatory Bowel Disease (IBD) and Spondyloarthritis (SpA) has been known for years, as has the concept that IBD is associated with an altered intestinal bacterial composition, a condition known as "dysbiosis". Recently, a state of intestinal dysbiosis has also been found in SpA. Dysbiosis in the field of IBD has been well characterized so far, as well as in SpA. The aim of this review is to summarize what is known to date and to emphasize the similarities between the microbiota conditions in these two diseases: particularly, an altered distribution in the gut of Enterobacteriaceae, Streptococcus, Haemophilus, Clostridium, Akkermansia, Ruminococcus, Faecalibacterium Prausnitzii, Bacteroides Vulgatus, Dialister Invisus, and Bifidubacterium Adolescentis is common to both IBD and SpA. At the same time, little is known about intestinal dysbiosis in IBD-related SpA. Only a single recent study has found an increase in Escherichia and Shigella abundances and a decrease in Firmicutes, Ruminococcaceae, and Faecalibacterium abundances in an IBD-related SpA group. Based on what has been discovered so far about the altered distribution of bacteria that unite both pathologies, it is appropriate to carry out further studies aiming to improve the understanding of IBD-related SpA for the purpose of developing new therapeutic strategies.

Male spondyloarthritis patients and those with longer disease duration have less severe disc degeneration: propensity score-matched comparison

Objective

Using whole spine sagittal T2 MRI, we aimed to compare the severity and prevalence of disc degeneration (DD) in axial SpA patients vs the general population and to determine any association between spinal inflammation, structural changes, mobility and DD among SpA patients.

Methods

Two prospectively collected cohorts of SpA patients (n = 411) and the general population (n = 2007) were recruited. Eventually, 967 participants from the populational cohort and 304 participants from the SpA cohort were analysed. Two hundred and nineteen matched pairs were generated by propensity score matching. Imaging parameters, including Pfirrmann grading, disc herniation, high-intensity zone, Schmorl's node, Modic change and anterior marrow change were studied and compared from C2/3 to L5/S1. DD was defined as Pfirrmann grade 4 or 5. Demographic factors, including age, sex and BMI, were collected. Multivariable linear regression was used to determine the association between spinal inflammation [Spondyloarthritis Research Consortium of Canada (SPARCC) spine MRI index], structural changes [modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS)] and mobility (BASMI) with lumbar Pfirrmann score.

Results

SpA patients had lower prevalence of DD (P < 0.001). The disease stage-stratified regression model showed that SPARCC spinal MRI index was associated with higher lumbar Pfirrmann scores in early disease (β = 0.196, P = 0.044), whereas mSASSS was associated with lower lumbar Pfirrmann scores in later disease (β = -0.138, P = 0.038). Males had higher mSASSS (P < 0.001) and lower odds of whole spine DD (odds ratio = 0.622, P = 0.028).

Conclusion

SpA patients had lower DD severity than the general population. Males had higher mSASSSs, and increased mSASSS at later disease was associated with less severe DD.

PLCG2 and IFNAR1: The Potential Biomarkers Mediated by Immune Infiltration and Osteoclast Differentiation of Ankylosing Spondylitis in the Peripheral Blood

Objectives

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease characterized by chronic spinal inflammation, arthritis, gut inflammation, and enthesitis. We aimed to identify the key biomarkers related to immune infiltration and osteoclast differentiation in the pathological process of AS by bioinformatic methods.

Methods

GSE25101 from the Gene Expression Omnibus was used to obtain AS-associated microarray datasets. We performed bioinformatics analysis using R software to validate different expression levels. The purpose of the GO and KEGG enrichment analyses of DEGs was to exclude key genes. Using weighted correlation network analysis (WGCNA), we examined all expression profile data and identified differentially expressed genes. The objective was to investigate the interaction between genetic and clinical features and to identify the essential relationships underlying coexpression modules. The CIBERSORT method was used to make a comparison of the immune infiltration in whole blood between the AS group and the control group. The WGCNA R program from Bioconductor was used to identify hub genes. RNA extraction reverse transcription and quantitative polymerase chain reaction were conducted in the peripheral blood collected from six AS patients and six health volunteers matched by age and sex.

Results

125 DEGs were identified, consisting of 36 upregulated and 89 downregulated genes that are involved in the cell cycle and replication processes. In the WGCNA, modules of MCODE with different algorithms were used to find 33 key genes that were related to each other in a strong way. Immune infiltration analysis found that naive CD4+ T cells and monocytes may be involved in the process of AS. PLCG2 and IFNAR1 genes were obtained by screening genes meeting the conditions of immune cell infiltration and osteoclast differentiation in AS patients among IGF2R, GRN, SH2D1A, LILRB3, IFNAR1, PLCG2, and TNFRSF1B. The results demonstrated that the levels of PLCG2 mRNA expression in AS were considerably higher than those in healthy individuals (P=0.003). IFNAR1 mRNA expression levels were considerably lower in AS than in healthy individuals (P < 0.0001).

Conclusions

Dysregulation of PLCG2 and IFNAR1 are key factors in disease occurrence and development of AS through regulating immune infiltration and osteoclast differentiation. Explaining the differences in immune infiltration and osteoclast differentiation between AS and normal samples will contribute to understanding the development of spondyloarthritis.

Beyond the horizon: Innovations and future directions in axial-spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease of the spine and sacroiliac joints. This review discusses recent advances across multiple scientific fields that promise to transform axSpA management. Traditionally, axSpA was considered an immune-mediated disease driven by human leukocyte antigen B27 (HLA-B27), interleukin (IL)-23/IL-17 signaling, biomechanics, and dysbiosis. Diagnosis relies on clinical features, laboratory tests, and imaging, particularly magnetic resonance imaging (MRI) nowadays. Management includes exercise, lifestyle changes, non-steroidal anti-inflammatory drugs and if this is not sufficient to achieve disease control also biological and targeted-synthetic disease modifying anti-rheumatic drugs. Beyond long-recognized genetic risks like HLA-B27, high-throughput sequencing has revealed intricate gene-environment interactions influencing dysbiosis, immune dysfunction, and aberrant bone remodeling. Elucidating these mechanisms promises screening approaches to enable early intervention. Advanced imaging is revolutionizing the assessment of axSpA's hallmark: sacroiliac bone-marrow edema indicating inflammation. Novel magnetic resonance imaging (MRI) techniques sensitively quantify disease activity, while machine learning automates complex analysis to improve diagnostic accuracy and monitoring. Hybrid imaging like synthetic MRI/computed tomography (CT) visualizes structural damage with new clarity. Meanwhile, microbiome analysis has uncovered gut ecosystem alterations that may initiate joint inflammation through HLA-B27 misfolding or immune subversion. Correcting dysbiosis represents an enticing treatment target. Moving forward, emerging techniques must augment patient care. Incorporating patient perspectives will be key to ensure innovations like genetics, microbiome, and imaging biomarkers translate into improved mobility, reduced pain, and increased quality of life. By integrating cutting-edge, multidisciplinary science with patients' lived experience, researchers can unlock the full potential of new technologies to deliver transformative outcomes. The future is bright for precision diagnosis, tightly controlled treatment, and even prevention of axSpA.

The gut ecosystem and immune tolerance

The gastrointestinal tract is home to the largest microbial population in the human body. The gut microbiota plays significant roles in the development of the gut immune system and has a substantial impact on the maintenance of immune tolerance beginning in early life. These microbes interact with the immune system in a dynamic and interdependent manner. They generate immune signals by presenting a vast repertoire of antigenic determinants and microbial metabolites that influence the development, maturation and maintenance of immunological function and homeostasis. At the same time, both the innate and adaptive immune systems are involved in modulating a stable microbial ecosystem between the commensal and pathogenic microorganisms. Hence, the gut microbial population and the host immune system work together to maintain immune homeostasis synergistically. In susceptible hosts, disruption of such a harmonious state can greatly affect human health and lead to various auto-inflammatory and autoimmune disorders. In this review, we discuss our current understanding of the interactions between the gut microbiota and immunity with an emphasis on: a) important players of gut innate and adaptive immunity; b) the contribution of gut microbial metabolites; and c) the effect of disruption of innate and adaptive immunity as well as alteration of gut microbiome on the molecular mechanisms driving autoimmunity in various autoimmune diseases.

Axial Spondyloarthritis: Evolving concepts regarding the disease's diagnosis and treatment

Spondyloarthritis (SpA) is a chronic inflammatory disease that affects the axial skeleton (axSpA) and/or the peripheral joints (p-SpA) and entheses. The natural history of SpA in the decades of the 80 and 90 s involved a progressive disease with pain, spinal stiffness, ankylosis of the axial skeleton, structural damage of peripheral joints, and a poor prognosis. In the last 20 years, enormous advances in understanding and managing SpA have occurred. With the introduction of the ASAS classification criteria and MRI, early disease recognition is now possible. The ASAS criteria widened the spectrum of SpA to include all the disease phenotypes, such as radiographic (r-axSpA), non-radiographic (nr-axSpA), and p-SpA and extraskeletal manifestations. Nowadays, the treatment of SpA is based on a shared decision between patients and rheumatologists and includes non-pharmacological and pharmacological therapies. Moreover, the discovery of TNFα, IL-17, which play a pivotal role in disease pathophysiology, has revolutionized disease management. Thus, new targeted therapies and many biological agents are now available and used in SpA patients. TNFα inhibitors (TNFi), IL-17, and JAK inhibitors were proven to be efficacious, with an acceptable toxicity profile. Overall, their efficacy and safety are comparable with some differences. Sustained clinical disease remission, low disease activity, improvement of patient's quality of life, and prevention of progression of structural damage, are the results of the above interventions. The concept of SpA has changed in the last 20 years. The disease burden can be ameliorated by early and accurate diagnosis and targeting therapies.

Shedding Light on the Role of ERAP1 in Axial Spondyloarthritis

Spondyloarthritis (SpA) is a multifactorial chronic inflammatory disease affecting the axial skeleton (axSpA) and/or peripheral joints (p-SpA) and entheses. The disease's pathogenesis depends on genetic, immunological, mechanical, and environmental factors. Endoplasmic reticulum aminopeptidase 1 (ERAP1) is a multifunctional enzyme that shapes the peptide repertoire presented by major histocompatibility complex (MHC) class I molecules. Genome-wide association studies (GWAS) have identified different single nucleotide polymorphisms (SNPs) in ERAP1 that are associated with several autoimmune diseases, including axSpA. Therefore, a deeper understanding of the ERAP1 role in axSpA could make it a potential therapeutic target for this disease and offer greater insight into its impact on the immune system. Here, we review the biological functions and structure of ERAP1, discuss ERAP1 polymorphisms and their association with axSpA, highlight the interaction between ERAP1 and human leukocyte antigen (HLA)-B27, and review the association between ERAP1 SNPs and axSpA clinical parameters.

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.

Transcriptome-wide association study identifies new susceptibility genes and pathways for spondyloarthritis

BACKGROUND

Spondyloarthritis (SpA) is a group of multifactorial bone diseases influenced by genetic factors, the environment and lifestyle. However, current studies have found a limited number of SpA-related genes, and the genetic and pathogenic mechanisms of SpA are still unclear.

METHODS

A tissue-specific transcriptome-wide association study (TWAS) of SpA was performed using GWAS (including 3966 SpA patients and 448,298 controls) summary data and gene expression weights of whole blood and skeletal muscle. The SpA-associated genes identified by TWAS were further compared with the differentially expressed genes (DEGs) identified in the SpA gene expression profile acquired from the Gene Expression Omnibus database (GEO, GSE58667). Finally, functional enrichment and annotation analyses of the identified genes were performed.

RESULTS

The TWAS detected 499 suggestive genes associated with SpA in whole blood and skeletal muscle, such as CTNNAL1 (PSM = 3.04 × 10-2, PWB = 9.58 × 10-3). The gene expression profile of SpA identified 20 candidate genes that overlapped in the TWAS data, such as MCM4 (PTWAS = 1.32 × 10-2, PDEG = 2.75 × 10-2) and KIAA1109 (PTWAS = 3.71 × 10-2, PDEG = 4.67 × 10-2). Enrichment analysis of the genes identified by TWAS identified 93 significant GO terms and 33 KEGG pathways, such as mitochondrion organization (GO: 0007005) and axon guidance (hsa04360).

CONCLUSION

We identified multiple candidate genes that were genetically related to SpA. Our study may provide novel clues regarding the genetic mechanism, diagnosis, and treatment of SpA.

Spondyloarthritis with inflammatory bowel disease: the latest on biologic and targeted therapies

Spondyloarthritis (SpA) encompasses a heterogeneous group of chronic inflammatory diseases that can affect both axial and peripheral joints, tendons and entheses. Among the extra-articular manifestations, inflammatory bowel disease (IBD) is associated with considerable morbidity and effects on quality of life. In everyday clinical practice, treatment of these conditions requires a close collaboration between gastroenterologists and rheumatologists to enable early detection of joint and intestinal manifestations during follow-up and to choose the most effective therapeutic regimen, implementing precision medicine for each patient's subtype of SpA and IBD. The biggest issue in this field is the dearth of drugs that are approved for both diseases, as only TNF inhibitors are currently approved for the treatment of full-spectrum SpA-IBD. Janus tyrosine kinase inhibitors are among the most promising drugs for the treatment of peripheral and axial SpA, as well as for intestinal manifestations. Other therapies such as inhibitors of IL-23 and IL-17, phosphodiesterase 4 inhibitor, α4β7 integrin blockers and faecal microbiota transplantation seem to only be able to control some disease domains, or require further studies. Given the growing interest in the development of novel drugs to treat both conditions, it is important to understand the current state of the art and the unmet needs in the management of SpA-IBD.

Exploring the common diagnostic gene KCNJ15 and shared pathway of ankylosing spondylitis and ulcerative colitis through integrated bioinformatics

Introduction: The similarity between ankylosing spondylitis (AS) and ulcerative colitis (UC) in incidence rate and pathogenesis has been revealed. But the common pathogenesis that explains the relationship between AS and UC is still lacked, and the related genetic research is limited. We purposed to explore shared biomarkers and pathways of AS and UC through integrated bioinformatics. Methods: Gene expression data of AS and UC were obtained in the GEO database. We applied weighted gene co-expression network analysis (WGCNA) to identify AS-related and UC-related co-expression gene modules. Subsequently, machine learning algorithm was used to further screen hub genes. We validated the expression level and diagnostic efficiency of the shared diagnostic gene of AS and UC in external datasets. Gene set enrichment analysis (GSEA) was applied to analyze pathway-level changes between disease group and normal group. Finally, we analyzed the relationship between hub biomarker and immune microenvironment by using the CIBERSORT deconvolution algorithm. Results: 203 genes were obtained by overlapping AS-related gene module and UC-related gene module. Through SVM-RFE algorithm, 19 hub diagnostic genes were selected for AS in GSE25101 and 6 hub diagnostic genes were selected for UC in GSE94648. KCNJ15 was obtained as a common diagnostic gene of AS and UC. The expression of KCNJ15 was validated in independent datasets, and the results showed that KCNJ15 were similarly upregulated in AS samples and UC samples. Besides, ROC analysis also revealed that KCNJ15 had good diagnostic efficacy. The GSEA analysis revealed that oxidative phosphorylation pathway was the shared pathway of AS and UC. In addition, CIBERSORT results revealed the correlation between KCNJ15 gene and immune microenvironment in AS and UC. Conclusion: We have explored a common diagnostic gene KCNJ15 and a shared oxidative phosphorylation pathway of AS and UC through integrated bioinformatics, which may provide a potential diagnostic biomarker and novel insight for studying the mechanism of AS-related UC.

Relationship between rs4349859 and rs116488202 polymorphisms close to MHC-I region and serum urate levels in patients with gout

BACKGROUND

Gout is the most common inflammatory rheumatic disease and elevated levels of serum urate (SU) are the main cause for its development. Major histocompatibility complex class 1 (MHC-1) plays an important role in the development of multiple inflammatory diseases; however, there is little evidence of its involvement in gout. The present study focused on evaluating the association of the rs4349859 and rs116488202 single nucleotide polymorphisms (SNPs) close to the MHC-1 region in patients with gout.

METHODS AND RESULTS

One hundred and seventy-six individuals of Mexican origin were included, of which 81 were patients with primary gout and 95 were healthy controls. The rs4349859 and rs116488202 SNPs were genotyped using TaqMan probes by allelic discrimination by real-time PCR. Serum concentrations of biochemical parameters were measured with enzymatic methods. Descriptive statistics were applied and P-values < 0.05 were considered significant. It was observed that the rs4349859 and rs116488202 SNPs showed significant association with the risk of gout (OR = 146, 95%CI = 44.8-480.2, P < 0.01; OR = 2885, 95%CI = 265-31398, P < 0.01, respectively). Our results also showed significantly higher serum SU levels in gout patients with respect to controls (P < 0.01) in the carriers of the GA genotype compared with the GG genotype of the rs4349859 variant, and in the carriers of the CT genotype compared with the CC genotype of the rs116488202 variant.

CONCLUSION

The study revealed that rs4349859 and rs116488202 SNPs close to MHC-I region confers strong susceptibility to gout in Mexican population, and the heterozygous genotypes of both were associated with higher levels of SU.

Air pollution exposure and auto-inflammatory and autoimmune diseases of the musculoskeletal system: a review of epidemiologic and mechanistic evidence

Auto-inflammatory and autoimmune diseases of the musculoskeletal system can be perceived as a spectrum of rheumatic diseases, with the joints and connective tissues are eroded severely that progressively develop chronic inflammation and lesion. A wide range of risk factors represented by genetic and environmental factors have been uncovered by population-based surveys and experimental studies. Lately, the exposure to air pollution has been found to be potentially involved in the mechanisms of occurrence or development of such diseases, principally manifest in oxidative stress, local and systemic inflammation, and epigenetic modifications, as well as the mitochondrial dysfunction, which has been reported to participate in the intermediate links. The lungs might serve as a starting area of air pollutants, which would cause oxidative stress-induced bronchial-associated lymphoid tissue (iBALT) to further to influence T, B cells, and the secretion of pro-inflammatory cytokines. The binding of aromatic hydrocarbon receptor (AhR) to the corresponding contaminant ligands tends to regulate the reaction of Th17 and Tregs. Furthermore, air pollution components might spur on immune and inflammatory responses by damaging mitochondria that could interact with and exacerbate oxidative stress and pro-inflammatory cytokines. In this review, we focused on the association between air pollution and typical auto-inflammatory and autoimmune diseases of the musculoskeletal system, mainly including osteoarthritis (OA), rheumatoid arthritis (RA), spondyloarthritis (SpA) and juvenile idiopathic arthritis (JIA), and aim to collate the mechanisms involved and the potential channels. A complete summary and in-depth understanding of the autoimmune and inflammatory effects of air pollution exposure should hopefully contribute new perspectives on how to formulate better public health policies to alleviate the adverse health effects of air pollutants.

How Has Molecular Biology Enhanced Our Undertaking of axSpA and Its Management

PURPOSE

This review aims at investigating pathophysiological mechanisms in spondyloarthritis (SpA). Analysis of genetic factors, immunological pathways, and abnormalities of bone metabolism lay the foundations for a better understanding of development of the axial clinical manifestations in patients, allowing physician to choose the most appropriate therapeutic strategy in a more targeted manner.

RECENT FINDINGS

In addition to the contribution of MHC system, findings emerged about the role of non-HLA genes (as ERAP1 and 2, whose inhibition could represent a new therapeutic approach) and of epigenetic mechanisms that regulate the expression of genes involved in SpA pathogenesis. Increasing evidence of bone metabolism abnormalities secondary to the activation of immunological pathways suggests the development of various bone anomalies that are present in axSpA patients. SpA are a group of inflammatory diseases with a multifactorial origin, whose pathogenesis is linked to the genetic predisposition, the action of environmental risk factors, and the activation of immune response. It is now well known how bone metabolism leads to long-term structural damage via increased bone turnover, bone loss and osteoporosis, osteitis, erosions, osteosclerosis, and osteoproliferation. These effects can exist in the same patient over time or even simultaneously. Evidence suggests a cross relationship among innate immunity, autoimmunity, and bone remodeling in SpA, making treatment approach a challenge for rheumatologists. Specifically, treatment targets are consistently increasing as new drugs are upcoming. Both biological and targeted synthetic drugs are promising in terms of their efficacy and safety profile in patients affected by SpA.

Interactions between NSAIDs, opioids and the gut microbiota - Future perspectives in the management of inflammation and pain

The composition of intestinal microbiota is influenced by a number of factors, including medications, which may have a substantial impact on host physiology. Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics are among those widely used medications that have been shown to alter microbiota composition in both animals and humans. Although much effort has been devoted to identify microbiota signatures associated with these medications, much less is known about the underlying mechanisms. Mucosal inflammation, changes in intestinal motility, luminal pH and bile acid metabolism, or direct drug-induced inhibitory effect on bacterial growth are all potential contributors to NSAID- and opioid-induced dysbiosis, however, only a few studies have addressed directly these issues. In addition, there is a notable overlap between the microbiota signatures of these drugs and certain diseases in which they are used, such as spondyloarthritis (SpA), rheumatoid arthritis (RA) and neuropathic pain associated with type 2 diabetes (T2D). The aims of the present review are threefold. First, we aim to provide a comprehensive up-to-date summary on the bacterial alterations caused by NSAIDs and opioids. Second, we critically review the available data on the possible underlying mechanisms of dysbiosis. Third, we review the current knowledge on gut dysbiosis associated with SpA, RA and neuropathic pain in T2D, and highlight the similarities between them and those caused by NSAIDs and opioids. We posit that drug-induced dysbiosis may contribute to the persistence of these diseases, and may potentially limit the therapeutic effect of these medications by long-term use. In this context, we will review the available literature data on the effect of probiotic supplementation and fecal microbiota transplantation on the therapeutic efficacy of NSAIDs and opioids in these diseases.

Sex differences in musculoskeletal injury and disease risks across the lifespan: Are there unique subsets of females at higher risk than males for these conditions at distinct stages of the life cycle?

Sex differences have been reported for diseases of the musculoskeletal system (MSK) as well as the risk for injuries to tissues of the MSK system. For females, some of these occur prior to the onset of puberty, following the onset of puberty, and following the onset of menopause. Therefore, they can occur across the lifespan. While some conditions are related to immune dysfunction, others are associated with specific tissues of the MSK more directly. Based on this life spectrum of sex differences in both risk for injury and onset of diseases, a role for sex hormones in the initiation and progression of this risk is somewhat variable. Sex hormone receptor expression and functioning can also vary with life events such as the menstrual cycle in females, with different tissues being affected. Furthermore, some sex hormone receptors can affect gene expression independent of sex hormones and some transitional events such as puberty are accompanied by epigenetic alterations that can further lead to sex differences in MSK gene regulation. Some of the sex differences in injury risk and the post-menopausal disease risk may be "imprinted" in the genomes of females and males during development and sex hormones and their consequences only modulators of such risks later in life as the sex hormone milieu changes. The purpose of this review is to discuss some of the relevant conditions associated with sex differences in risks for loss of MSK tissue integrity across the lifespan, and further discuss several of the implications of their variable relationship with sex hormones, their receptors and life events.

Novel peripheral blood diagnostic biomarkers screened by machine learning algorithms in ankylosing spondylitis

Background: Ankylosing spondylitis (AS) is a chronic inflammatory disorder of unknown etiology that is hard to diagnose early. Therefore, it is imperative to explore novel biomarkers that may contribute to the easy and early diagnosis of AS. Methods: Common differentially expressed genes between normal people and AS patients in GSE73754 and GSE25101 were screened by machine learning algorithms. A diagnostic model was established by the hub genes that were screened. Then, the model was validated in several data sets. Results: IL2RB and ZDHHC18 were screened using machine learning algorithms and established as a diagnostic model. Nomograms suggested that the higher the expression of ZDHHC18, the higher was the risk of AS, while the reverse was true for IL2RB in vivo. C-indexes of the model were no less than 0.84 in the validation sets. Calibration analyses suggested high prediction accuracy of the model in training and validation cohorts. The area under the curve (AUC) values of the model in GSE73754, GSE25101, GSE18781, and GSE11886 were 0.86, 0.84, 0.85, and 0.89, respectively. The decision curve analyses suggested a high net benefit offered by the model. Functional analyses of the differentially expressed genes indicated that they were mainly clustered in immune response-related processes. Immune microenvironment analyses revealed that the neutrophils were expanded and activated in AS while some T cells were decreased. Conclusion: IL2RB and ZDHHC18 are potential blood biomarkers of AS, which might be used for the early diagnosis of AS and serve as a supplement to the existing diagnostic methods. Our study deepens the insight into the pathogenesis of AS.

A2A adenosine receptor agonist reduced MMP8 expression in healthy M2-like macrophages but not in macrophages from ankylosing spondylitis patients

BACKGROUND

Ankylosing spondylitis (AS) is an inflammatory autoimmune disease that mostly affects different joints of the body. Macrophages are the predominant cells that mediate disease progression by secreting several pro-inflammatory mediators. Different receptors are involved in macrophages' function including the adenosine receptors (AR). Our main objective in this study was to assess the effect of applying A_2A adenosine receptor agonist (CGS-21,680) on the gene expression of inflammatory mediators including bone morphogenetic proteins (BMP)-2, 4 and matrix metalloproteinases (MMP)-3, 8, 9, and 13 on the macrophages from AS patients compared to healthy macrophages.

METHODS

Monocytes were isolated from the whole blood of 28 individuals (AS patients and healthy controls in a 1:1 ratio). Macrophages were differentiated using macrophage colony-stimulating factor (M-CSF), and flow cytometry was performed to confirm surface markers. CGS-21,680 was used to treat cells that had been differentiated. Using SYBR green real-time PCR, relative gene expression was determined.

RESULTS

Activating A_2AAR diminished MMP8 expression in healthy macrophages while it cannot reduce MMP8 expression in patients' macrophages. The effect of A_2AAR activation on the expression of BMP2 and MMP9 reached statistical significance neither in healthy macrophages nor in the patients' group. We also discovered a significant positive connection between MMP8 expression and patient scores on the Bath ankylosing spondylitis functional index (BASFI).

CONCLUSION

Due to the disability of A_2AAR activation in the reduction of MMP8 expression in patients' macrophages and the correlation of MMP8 expression with BASFI index in patients, these results represent defects and dysregulations in the related signaling pathway in patients' macrophages.

Gut Microbiota and Inflammatory Cytokine Changes in Patients with Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by sacroiliac joint lesions and spinal ascending involvement. The aim of this work was at investigating the gut microbiota profile and proinflammatory cytokines in AS patients. Gut microbiota of AS patients was clearly different from that of healthy human controls. 16S rRNA sequencing analysis demonstrated a changed microbial diversity in the AS patients, and there was a significant increase in the abundance of Cyanobacteria, Deinococcota, Patescibacteria, Actinobacteriota, and Synergistota at a phyla level increased in AS, while the relative abundance of Acidobacteriota, Bdellovibrionota, Campylobacterota, Chloroflexi, Gemmatimonadota, Myxococcota, Nitrospirota, Proteobacteria, and Verrucomicrobiota declined in AS patients. ELISA results for the markers of inflammation in the AS patients revealed increased concentrations of proinflammatory cytokines such as IL-23, IL-17, and IFN-γ. Our findings support the fact that the intestinal microbiota are altered in AS with an inflammatory status, which indicates that gut microbiota should be a potential target for ankylosing spondylitis therapy.

Interim 2-Year Analysis from SERENA: A Real-World Study in Patients with Psoriatic Arthritis or Ankylosing Spondylitis Treated with Secukinumab

INTRODUCTION

Sustained improvement of high degree in clinical outcomes have been demonstrated in phase 3 trials with secukinumab in both psoriatic arthritis (PsA) and ankylosing spondylitis (AS). The objective of the SERENA study was to evaluate the effectiveness, retention rates, and safety of secukinumab in patients with PsA and AS.

METHODS

SERENA is an ongoing, longitudinal, real-world observational study involving patients with moderate-to-severe psoriasis, PsA, or AS. Patients had received at least 16 weeks of secukinumab treatment before recruitment to the study. Retention rate was defined as percentage of patients who continued secukinumab treatment over the course of study. Effectiveness of secukinumab in AS and PsA cohorts was assessed using descriptive statistics.

RESULTS

The current interim analysis included 1004 patients with PsA or AS. Overall secukinumab retention rates at 2 years after enrolment were 74.9 and 78.9% in patients with PsA and AS, respectively. At baseline and at 2 years, swollen joint count [3.3 (5.8) vs. 2.9 (5.8)], tender joint count [6.3 (9.4) vs. 5.6 (7.2)] in patients with PsA and BASDAI scores [3.2 (2.3) vs. 2.9 (2.3)] in patients with AS, suggest sustained effectiveness for patients remaining on secukinumab for at least 2 years after enrolment. A total of 73 patients had treatment interruption; 78% of these patients reinitiated secukinumab without a loading dose. No new or unexpected safety signals were reported.

CONCLUSIONS

After more than 2 years since initiation, secukinumab demonstrated high retention rates and favorable safety profile as well as sustained effectiveness in patients who continued secukinumab treatment.

Modulation of Inflammation by Plant-Derived Nutraceuticals in Tendinitis

Tendinitis (tendinopathy) is a pro-inflammatory and painful tendon disease commonly linked with mechanical overuse and associated injuries, drug abuse, and lifestyle factors (including poor diet and physical inactivity) that causes significant healthcare expenditures due to its high incidence. Nuclear factor kappa B (NF-κB) is one of the major pro-inflammatory transcription factors, along with other inflammation signaling pathways, triggered by a variety of stimuli, including cytokines, endotoxins, physical and chemical stressors, hypoxia, and other pro-inflammatory factors. Their activation is known to regulate the expression of a multitude of genes involved in inflammation, degradation, and cell death. The pathogenesis of tendinitis is still poorly understood, whereas efficient and sustainable treatment is missing. Targeting drug suppression of the key inflammatory regulators represents an effective strategy for tendinitis therapy, but requires a comprehensive understanding of their principles of action. Conventional monotherapies are often ineffective and associated with severe side effects in patients. Therefore, agents that modulate multiple cellular targets represent therapeutic treatment potential. Plant-derived nutraceuticals have been shown to act as multi-targeting agents against tendinitis via various anti-oxidant and anti-inflammatory mechanisms, whereat they were able to specifically modulate numerous signaling pathways, including NF-κB, p38/MAPK, JNK/STAT3, and PI3K/Akt, thus down-regulating inflammatory processes. This review discusses the utility of herbal nutraceuticals that have demonstrated safety and tolerability as anti-inflammatory agents for the prevention and treatment of tendinitis through the suppression of catabolic signaling pathways. Limitations associated with the use of nutraceuticals are also described.

Comparison of immune cells and diagnostic markers between spondyloarthritis and rheumatoid arthritis by bioinformatics analysis

Background

Spondyloarthritis (SpA) and rheumatoid arthritis (RA) are chronic autoimmune diseases, but they are usually difficult to distinguish in the early stage of the diseases. The purpose of this study is to explore the differences of immune mechanism and diagnostic markers through bioinformatics analysis.

Methods

First, microarray datasets from patients with SpA, RA and normal controls were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between groups were identified in R software. Functional and pathway enrichment of DEGs were analyzed by David database. Then, we screened the hub genes using Cytoscape plugin, and constructed the protein–protein interaction (PPI) network and heatmap of hub genes. After that, CIBERSORT was used to evaluate the differences and connections of immune cells in SpA and RA, and screened out diagnostic markers. Correlation analysis was used to analyze the relationship between immune cells and diagnostic markers. Finally, quantitative real-time polymerase chain reaction (qRT‐PCR) was used to verify the effectiveness of immunodiagnostic markers.

Results

We obtained three datasets, from which we can see that the functional enrichment of DEGs is mainly in cell chemotaxis, lymphocyte activation, primary immunodeficiency and other immune responses. The difference of immune cells between SpA, RA and normal control was concentrated in B, T lymphocytes cells, macrophages and dendritic cells. C19orf12 + S1PR3 is most associated with these immune cells and S1PR3 can be used as a diagnostic marker of this kind of immune diseases. In addition, MZB1 + XIST is closely related to T cells, NK cells and dendritic cells, and is expected to be used as a marker to distinguish the two diseases.

Conclusion

Although the clinical manifestations of SpA and RA are similar, the pathogenesis is different. The screening of immune cells and diagnostic markers provides a more accurate target for the treatment of this kind of diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03390-y.

A Short ERAP2 That Binds IRAP Is Expressed in Macrophages Independently of Gene Variation

The M1 zinc metalloproteases ERAP1, ERAP2, and IRAP play a role in HLA-I antigen presentation by refining the peptidome either in the ER (ERAP1 and ERAP2) or in the endosomes (IRAP). They have also been entrusted with other, although less defined, functions such as the regulation of the angiotensin system and blood pressure. In humans, ERAP1 and IRAP are commonly expressed. ERAP2 instead has evolved under balancing selection that maintains two haplotypes, one of which undergoing RNA splicing leading to nonsense-mediated decay and loss of protein. Hence, likewise in rodents, wherein the ERAP2 gene is missing, about a quarter of the human population does not express ERAP2. We report here that macrophages, but not monocytes or other mononuclear blood cells, express and secrete an ERAP2 shorter form independent of the haplotype. The generation of this "short" ERAP2 is due to an autocatalytic cleavage within a distinctive structural motif and requires an acidic micro-environment. Remarkably, ERAP2 "short" binds IRAP and the two molecules are co-expressed in the endosomes as well as in the cell membrane. Of note, the same phenomenon could be observed in some cancer cells. These data prompt us to reconsider the role of ERAP2, which might have been maintained in humans due to fulfilling a relevant function in its "short" form.

Effects of Biological/Targeted Therapies on Bone Mineral Density in Inflammatory Arthritis

Inflammatory arthritis has been reported to be associated with the development of osteoporosis. Recent research has investigated the mechanisms of bone metabolism in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Progress in both animal and clinical studies has provided a better understanding of the osteoclastogenesis-related pathways regarding the receptor activator of nuclear factor-κB ligand (RANKL), anti-citrullinated protein antibodies (ACPAs), and Wnt signaling and Dickkopf-related protein 1 (Dkk-1). The complex interplay between inflammatory cytokines and bone destruction has been elucidated, especially that in the interleukin-17/23 (IL-17/23) axis and Janus kinase and signal transducer and activator of transcription (JAK-STAT) signaling. Moreover, advances in biological and targeted therapies have achieved essential modifications to the bone metabolism of these inflammatory arthritis types. In this narrative review, we discuss recent findings on the pathogenic effects on bone in RA and SpA. Proinflammatory cytokines, autoantibodies, and multiple signaling pathways play an essential role in bone destruction in RA and SpA patients. We also reviewed the underlying pathomechanisms of bone structure in biological and targeted therapies of RA and SpA. The clinical implications of tumor necrosis factor inhibitors, abatacept, rituximab, tocilizumab, Janus kinase inhibitors, and inhibitors of the IL-17/23 axis are discussed. Since these novel therapeutics provide new options for disease improvement and symptom control in patients with RA and SpA, further rigorous evidence is warranted to provide a clinical reference for physicians and patients.