Ankylosing spondylitis patients display altered dendritic cell and T cell populations that implicate pathogenic roles for the IL-23 cytokine axis and intestinal inflammation

Angiogenesis-related immune response may be the prelude to the syndesmophyte formation in Ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic autoimmune arthritis that mainly affects spine joints. To date, the pathogenesis of AS remains unclear, although immune cells and innate immune response cytokines have been suggested to be crucial players.

METHODS

By adopting a single-cell RNA sequencing approach in the AS cynomolgus model, we profiled and characterized PBMC proportions along disease progression.

RESULTS

Here, our primary focus was on the activation of an immune cascade-initiating lymphocyte subtype known as CD4+CXCR5+ T follicular helper (Tfh) cells. These Tfhs demonstrated a localized residence in AS bone lesion as an ectopic lymphoid structure. Moreover, Tfhs would serve as an upstream initiator for a pro-angiogenic cascade. Then, an expansion in CD14+ monocytes and DC cells subsets resulted in enhanced expression of angiogenesis genes in these AS cynomolgus monkeys. With a confirmed higher abundance of TNF-α accompanying H-type vascular invasion in the osteophytic region, pronounced expansion of Tfhs at such lesion site signaling for monocytes and DCs intrusion is considered as the prelude to the characteristic angiogenic bony outgrowth in AS known as syndesmophytes.

CONCLUSIONS

We explored the intimate relationship between local inflammation and bone formation in AS from the perspective of nascent vascularisation. Hence, our study lays the foundation for elucidating a unified AS pathogenesis through the immune-angiogenesis-osteogenesis axis.

Causal relationship between the immune cells and ankylosing spondylitis: univariable, bidirectional, and multivariable Mendelian randomization

Background

Ankylosing spondylitis (AS) is an autoimmune disease that affects millions of individuals. Immune cells have been recognized as having a crucial role in the pathogenesis of AS. However, their relationship has not been fully explored.

Methods

We chose to employ Mendelian randomization (MR) to investigate the potential correlation between immune cells and AS. We sourced the data on immune cells from the latest genome-wide association studies (GWASs). We obtained data on AS from the FinnGen consortium. Our comprehensive univariable MR analysis covered 731 immune cells to explore its potential causal relationship with AS. The primary analysis method was inverse-variance weighted (IVW). Additionally, we used Cochran's Q test and the MR-Egger intercept test to assess the presence of pleiotropy and heterogeneity. We examined whether our results could be influenced by individual single-nucleotide polymorphisms (SNPs) using the leave-one-out test. We conducted a bidirectional MR to investigate the reverse relationship. We also applied multivariable MR to decrease the potential influence between the immune cells.

Results

Overall, our univariable MR analysis revealed eight immune cells associated with AS. Among these, four immune cells contributed to an increased risk of AS, while four immune cells were identified as protective factors for AS. However, the Bonferroni test confirmed only one risk factor and one protective factor with a significance level of p < 6.84E-05. CD8 on effector memory CD8+ T cell could increase the risk of AS (p: 1.2302E-05, OR: 2.9871, 95%CI: 1.8289-4.8786). HLA DR on CD33dim HLA DR+ CD11b+ could decrease the risk of AS (p: 1.2301E-06, OR: 0.5446, 95%CI: 0.4260-0.6962). We also identified a bidirectional relationship between CD4 on CD39+ activated CD4 regulatory T cells and AS utilizing the bidirectional MR. To address potential confounding among immune cells, we employed multivariable MR analysis, which revealed that only one immune cell had an independent effect on AS. HLA DR on CD33dim HLA DR+ CD11b+ could decrease the risk of AS (p: 2.113E-06, OR: 0.0.5423, 95%CI: 0.4210-0.6983). Our findings were consistently stable and reliable.

Conclusions

Our findings indicated a potential link between immune cells and AS, which could provide a new idea for future research. Nevertheless, the specific underlying mechanisms require further exploration.

The study of the effect of HLA-B27 on THP-1 monocytic cells survival and its mechanism

OBJECTIVE

Previous studies have shown that human leukocyte antigen (HLA)-B27 induces the accumulation of unfolded proteins in the endoplasmic reticulum (ER) to cause ER stress, resulting in the unfold protein response (UPR), apoptosis and autophagy. However, it is still unknown whether it affects the survival of monocytes. In this study, we attempted to examine the effect of HLA-B27 gene knockout on the proliferation and apoptosis of THP-1 monocytic cell line and its potential mechanism.

METHODS

HLA-B27 gene knockout THP-1 cell line was constructed by lentivirus infection, and knockout efficiency was detected by immunofluorescence, quantitative reverse transcription - polymerase chain reaction (qRT-PCR) and western blot. Cell Counting Kit-8 (CCK-8) method and Annexin-V/PI double staining were used to detect the proliferation and apoptosis of the constructed THP-1 cell line, respectively. qRT-PCR was used to detect the effect of HLA-B27 inhibition on the expressions of ER molecular chaperone binding immunoglobulin protein (BiP) and genes about the UPR pathway. The proliferation rate of human BiP protein-stimulated THP-1 cells was detected by CCK-8 method.

RESULTS

HLA-B27 gene knockout THP-1 cells were successfully constructed by lentivirus infection. Knockout of HLA-B27 effectively promoted the proliferation of THP-1 cells and inhibited the apoptosis induced by cisplatin. qRT-PCR showed that BiP was synchronously increased, while activation of UPR pathway was inhibited. Stimulation with human BiP promoted the proliferation of THP-1 cells in a concentration-dependent manner.

CONCLUSIONS

HLA-B27 inhibition can promote the proliferation and inhibit the apoptosis of THP-1 cells. The inhibition function may be achieved through promotion of BiP and inhibition of UPR pathway activation.

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.

Efficacy and Safety of Curcumin and Curcuma longa Extract in the Treatment of Arthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trial

Background

Modern pharmacological research found that the chemical components of Curcuma longa L. are mainly curcumin and turmeric volatile oil. Several recent randomized controlled trials (RCT) have shown that curcumin improves symptoms and inflammation in patients with arthritis.

Methods

Pubmed, Cochran Library, CNKI, and other databases were searched to collect the randomized controlled trials (RCTs). Then, the risk of bias of RCTs were assessed and data of RCTs were extracted. Finally, RevMan 5.3 was utilized for meta-analysis.

Results

Twenty-nine (29) RCTs involving 2396 participants and 5 types of arthritis were included. The arthritis included Ankylosing Spondylitis (AS), Rheumatoid Arthritis (RA), Osteoarthritis (OA), Juvenile idiopathic arthritis (JIA) and gout/hyperuricemia. Curcumin and Curcuma longa Extract were administered in doses ranging from 120 mg to 1500 mg for a duration of 4-36 weeks. In general, Curcumin and Curcuma longa Extract showed safety in all studies and improved the severity of inflammation and pain levels in these arthritis patients. However, more RCTs are needed in the future to elucidate the effect of Curcumin and Curcuma longa Extract supplementation in patients with arthritis, including RA, OA, AS and JIA.

Conclusion

Curcumin and Curcuma longa Extract may improve symptoms and inflammation levels in people with arthritis. However, due to the low quality and small quantity of RCTs, the conclusions need to be interpreted carefully.

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.

Spondyloarthritides: Theories and beyond

Spondyloarthritides (SpA) are a family of interrelated rheumatic disorders with a typical disease onset ranging from childhood to middle age. If left untreated, they lead to a severe decrease in patients' quality of life. A succesfull treatment strategy starts with an accurate diagnosis which is achieved through careful analysis of medical symptoms. Classification criterias are used to this process and are updated on a regular basis. Although there is a lack of definite knowledge on the disease etiology of SpA, several studies have paved the way for understanding plausible risk factors and developing treatment strategies. The significant increase of HLA-B27 positivity in SpA patients makes it a strong candidate as a predisposing factor and several theories have been proposed to explain HLA-B27 driven disease progression. However, the presence of HLA-B27 negative patients underlines the presence of additional risk factors. The current treatment options for SpAs are Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), TNF inhibitors (TNFis), Disease-Modifying Anti-Rheumatic Drugs (DMARDs) and physiotherapy yet there are ongoing clinical trials. Anti IL17 drugs and targeted synthetic DMARDs such as JAK inhibitors are also emerging as treatment alternatives. This review discusses the current diagnosis criteria, treatment options and gives an overview of the previous findings and theories to clarify the possible contributors to SpA pathogenesis with a focus on Ankylosing Spondylitis (AS) and enthesitis-related arthritis (ERA).

Cellular and molecular diversity in spondyloarthritis

The spondyloarthritides are a cluster of inflammatory rheumatic diseases characterized by different diagnostic entities with heterogeneous phenotypes. The current classification system groups spondyloarthritis patients in two main categories, axial and peripheral spondyloarthritis, providing a framework wherein the clinical picture guides the treatment. However, the heterogeneity of the clinical manifestations of the pathologies, even when residing in the same group, highlights the importance of analyzing the smallest features of each entity to understand how different cellular subsets evolve, what the underlying mechanisms are and what biological markers can be identified and validated to evaluate the stage of disease and the corresponding efficacy of treatments. In this review, we will focus mostly on axial spondyloarthritis, report current knowledge concerning the cellular populations involved in its pathophysiology, and their molecular diversity. We will discuss the implications of such a diversity, and their meaning in terms of patients' stratification.

Immunopathophysiology of Juvenile Spondyloarthritis (jSpA): The "Out of the Box" View on Epigenetics, Neuroendocrine Pathways and Role of the Macrophage Migration Inhibitory Factor (MIF)

Juvenile spondyloarthritis (jSpA) is a an umbrella term for heterogeneous group of related seronegative inflammatory disorders sharing common symptoms. Although it mainly affects children and adolescents, it often remains active during adulthood. Genetic and environmental factors are involved in its occurrence, although the exact underlying immunopathophysiology remains incompletely elucidated. Accumulated evidence suggests that, in affected patients, subclinical gut inflammation caused by intestinal dysbiosis, is pivotal to the future development of synovial-entheseal complex inflammation. While the predominant role of IL17/23 axis, TNF-α, and IL-7 in the pathophysiology of SpA, including jSpA, is firmly established, the role of the cytokine macrophage migration inhibitory factor (MIF) is generally overlooked. The purpose of this review is to discuss and emphasize the role of epigenetics, neuroendocrine pathways and the hypothalamic-pituitary (HPA) axis, and to propose a novel hypothesis of the role of decreased NLRP3 gene expression and possibly MIF in the early phases of jSpA development. The decreased NLRP3 gene expression in the latter, due to hypomethylation of promotor site, is (one of) the cause for inflammasome malfunction leading to gut dysbiosis observed in patients with early jSpA. In addition, we highlight the role of MIF in the complex innate, adaptive cellular and main effector cytokine network, Finally, since treatment of advanced bone pathology in SpA remains an unmet clinical need, I suggest possible new drug targets with the aim to ultimately improve treatment efficacy and long-term outcome of jSpA patients.

Genetics of Ankylosing Spondylitis-Focusing on the Ethnic Difference Between East Asia and Europe

Ankylosing spondylitis (AS) is a common, highly heritable inflammatory arthritis affecting the mainly axial joints in both East Asia and Europe. To date, the pathogenesis of AS is still unknown, although we know that genetics play a vital role in it. The HLA-B27 allele is found in over 85% of AS patients. However, strong evidence suggests that other major histocompatibility complex (MHC) and non-MHC genes are also involved in the pathogenesis. In addition, current data showed that there were significant differences in both genomics and metagenomics among the different ethnic populations. The investigation of the key role of the microbiome in AS pathogenesis also highlighted the host–microbiome genetic interactions. Here, we systematically review current AS genetic research data and further compare genetic differences, especially between East Asian and European groups, which may highlight the challenge in future genetic studies.

Osteoimmunological insights into the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS.

LACC1 Required for NOD2-Induced, ER Stress-Mediated Innate Immune Outcomes in Human Macrophages and LACC1 Risk Variants Modulate These Outcomes

LACC1 genetic variants are associated with multiple immune-mediated diseases. However, laccase domain containing-1 (LACC1) functions are incompletely defined. We find that upon stimulation of the pattern-recognition receptor (PRR) NOD2, LACC1 localizes to the endoplasmic reticulum (ER) and forms a complex with ER-stress sensors. All three ER-stress branches, PERK, IRE1α, and ATF6, are required for NOD2-induced signaling, cytokines, and antimicrobial pathways in human macrophages. LACC1, and its localization to the ER, is required for these outcomes. Relative to wild-type (WT) LACC1, transfection of the common Val254 and rare Arg284 immune-mediated disease-risk LACC1 variants into HeLa cells and macrophages, as well as macrophages from LACC1 Val254 carriers, shows reduced NOD2-induced ER stress-associated outcomes; these downstream outcomes are restored by rescuing ER stress. Therefore, we identify ER stress to be essential in PRR-induced outcomes in macrophages, define a critical role for LACC1 in these ER stress-dependent events, and elucidate how LACC1 disease-risk variants mediate these outcomes.

Quantitative Proteomic Analyses To Reveal the Key Features of Proteins in New Onset Ankylosing Spondylitis Patients

Ankylosing spondylitis (AS) is a chronic immune-mediated disease. Various immune cells play an essential role in the AS pathogenesis. However, the specific pathogenesis of AS has not been well understood. Proteomic profiles of peripheral blood mononuclear cells (PBMCs) were applied to reveal the specific pathogenesis of AS. Quantitative proteomic analyses were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based methods to investigate the protein profiling of PBMCs from new-onset AS patients (n = 9) and healthy controls (n = 9). We identified 782 differentially expressed proteins (DEPs) and 527 differentially phosphorylated proteins (DPPs) between AS patients and healthy controls. The subcellular location of DEPs and DPPs showed that most of the DEPs were from the cytoplasm (n = 296, 38%), were extracellular (n = 141, 18%), and from the nucleus (n = 114, 15%); most of the DPPs were from the cytoplasm (n = 37, 34%), nucleus (n = 35, 32%), and plasma membrane (n = 10, 9%). We further identified 89 proteins with both expression and phosphorylation differences. The functional annotation of the 89 differentially expressed and phosphorylated proteins enriched in the antigen processing and presentation pathway. Four DEPs with six phosphorylated positions were found in the antigen processing and presentation pathway. The differentially expressed and phosphorylated proteins may be helpful to uncover the pathogenesis of AS. The six AS-specific proteins may serve as candidate markers for AS diagnosis and new treatment targets.

Aberrant distribution and function of plasmacytoid dendritic cells in patients with ankylosing spondylitis are associated with unfolded protein response

Although human leucocyte antigen (HLA)-B27 is strongly associated with ankylosing spondylitis (AS), the association of unfolded protein response (UPR) induced by HLA-B27 misfolding in AS remains controversial. Since dendritic cells (DCs) are crucial in induction of AS in HLA-B27-transgenic rats, and plasmacytoid DCs (pDCs) belong to one type of DCs, we here aim to study the relevance of pDCs and UPR in AS. Peripheral pDCs were isolated from 27 HLA-B27(+) AS patients and 37 controls. The bone marrow (BM) and synovium of inflamed hips from AS patients and controls were obtained. We found a significantly higher frequency of pDCs in the peripheral blood, BM, or inflamed synovium of hips, which is associated with the enhanced expression of pDC trafficking molecules, CCR6 and CCL20 in the synovium of AS patients. Functional analysis further revealed that several inflammatory cytokines, including TNFα, IL-6, and IL-23, secreted by pDCs were significantly increased in AS patients as compared with those in controls. Remarkably, protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway in UPR was up-regulated in pDCs of AS patients. Notably, PERK inhibitor treatment significantly inhibited the enhanced cytokine production by pDCs of AS patients. Further, the extent of PERK activation was significantly associated with the increased disease severity of AS patients. Our data uncover the aberrant distribution and function of pDCs in AS patients. The up-regulated PERK pathway in UPR of pDCs not only contributes to enhanced cytokine production of pDCs, but also is associated with increased disease activity of AS patients.

Ankylosing spondylitis: etiology, pathogenesis, and treatments

Ankylosing spondylitis (AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain; additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis. However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.

Ankylosing spondylitis and mesenchymal stromal/stem cell therapy: a new therapeutic approach

Ankylosing spondylitis (AS) is an inflammatory rheumatoid disease categorized within spondyloarthropathies (SpA) and manifested by chronic spinal arthritis. Several innate and adaptive immune cells and secreted-mediators have been indicated to play a role in AS pathogenesis. Considering the limitations of current therapeutic approaches (NSAIDs, glucocorticoids, DMARDs and biologic drugs), finding new treatments with fewer side effects and high therapeutic potentials are required in AS. Mesenchymal stem cells (MSCs) with considerable immunomodulatory and regenerative properties could be able to attenuate the inflammatory responses and help tissue repair by cell-to-cell contact and secretion of soluble factors. Moreover, MSCs do not express HLA-DR, which renders them a favorable therapeutic choice for transplantation in immune-mediated disorders. In the present review, we describe immunopathogenesis and current treatments restrictions of AS. Afterwards, immunomodulatory properties and applications of MSCs in immune-mediated disorders, as well as recent findings of clinical trials involving mesenchymal stem cell therapy (MSCT) in ankylosing spondylitis, will be discussed in detail. Additional studies are required to investigate several features of MSCT such as cell origin, dosage, administration route and, specifically, the most suitable stage of disease for ideal intervention.

The role of HLA-B*27 in spondyloarthritis

The mechanism by which HLA-B*27 predisposes to spondyloarthritis remains unresolved. Arthritogenic peptides have not been defined in humans and are not involved in experimental models of spondyloarthritis. Aberrant properties of HLA-B*27 can activate the IL-23/IL-17 axis in HLA-B*27 transgenic rats and humans. In HLA-B*27-independent rodent models, spondyloarthritis can be driven by IL-23 triggering entheseal-resident CD4^-/CD8^- T cells or CD4⁺ Th17 T cells. These findings point toward noncanonical mechanisms linking HLA-B*27 to the disease and provide a potential explanation for HLA-B*27-negative spondyloarthritis. Gut microbial dysbiosis may be important in the development of spondyloarthritis. HLA-B*27-induced changes in gut microbiota are complex and suggest an ecological model of dysbiosis in rodents. The importance of the IL-23/IL-17 axis in ankylosing spondylitis has been demonstrated by studies showing efficacy of IL-17. Although deciphering the precise role(s) of HLA-B*27 in disease requires further investigation, considerable progress has been made in understanding this complex relationship.

Functional intraepithelial lymphocyte changes in inflammatory bowel disease and spondyloarthritis have disease specific correlations with intestinal microbiota

Background

Dysbiosis occurs in spondyloarthritis (SpA) and inflammatory bowel disease (IBD), which is subdivided into Crohn’s disease (CD) and ulcerative colitis (UC). The immunologic consequences of alterations in microbiota, however, have not been defined. Intraepithelial lymphocytes (IELs) are T cells within the intestinal epithelium that are in close contact with bacteria and are likely to be modulated by changes in microbiota. We examined differences in human gut-associated bacteria and tested correlation with functional changes in IELs in patients with axial SpA (axSpA), CD, or UC, and in controls.

Methods

We conducted a case-control study to evaluate IELs from pinch biopsies of grossly normal colonic tissue from subjects with biopsy-proven CD or UC, axSpA fulfilling Assessment of SpondyloArthritis International Society (ASAS) criteria and from controls during endoscopy. IELs were harvested and characterized by flow cytometry for cell surface markers. Secreted cytokines were measured by ELISA. Microbiome analysis was by 16S rRNA gene sequencing from rectal swabs. Statistical analyses were performed with the Kruskal-Wallis and Spearman’s rank tests.

Results

The total number of IELs was significantly decreased in subjects with axSpA compared to those with IBD and controls, likely due to a decrease in TCRβ+ IELs. We found strong, significant negative correlation between peripheral lymphocyte count and IEL number. IELs secreted significantly increased IL-1β in patients with UC, significantly increased IL-17A and IFN-γ in patients with CD, and significantly increased TNF-α in patients with CD and axSpA as compared to other cohorts. For each disease subtype, IELs and IEL-produced cytokines were positively and negatively correlated with the relative abundance of multiple bacterial taxa.

Conclusions

Our data indicate differences in IEL function among subjects with axSpA, CD, and UC compared to healthy controls. We propose that the observed correlation between altered microbiota and IEL function in these populations are relevant to the pathogenesis of axSpA and IBD, and discuss possible mechanisms.

Trial registration

ClinicalTrials.gov, NCT02389075. Registered on 17 March 2015.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1639-3) contains supplementary material, which is available to authorized users.

The pathogenic role of dendritic cells in non-infectious anterior uveitis

BACKGROUND

Anterior uveitis (AU) is characterised by infiltration of immune cells into the anterior chamber of the eye. Dendritic cells (DC) are professional antigen presenting cells that initiate and promote inflammation. This study aims to characterise DC in AU and to examine the effects of aqueous humor (AqH) on DC maturation and function.

METHODS

The frequency and phenotype of AU and healthy control (HC) circulating DC was examined. AU and HC AqH was immunostained and assessed by flow cytometry. The effect of AU and HC AqH on DC activation and maturation was examined and subsequent effects on CD4⁺ T cell proliferation assessed.

RESULTS

AU peripheral blood demonstrated decreased circulating myeloid and plasmacytoid DC. Within AU AqH, three populations of CD45⁺ cells were significantly enriched compared to HC; DCs (CD11c⁺ HLA-DR⁺), neutrophils (CD15⁺ CD11c⁺) and T cells (CD4⁺ and CD8⁺). A significant increase in IFNγ, IL8 and IL6 was observed in the AU AqH, which was also significantly higher than that of paired serum. AU AqH induced expression of CD40 and CD80 on DC, which resulted in increased T cell proliferation and the production of GM-CSF, IFNγ and TNFα.

CONCLUSION

DC are enriched at the site of inflammation in AU. Our data demonstrate an increase in inflammatory mediators in the AU inflamed microenvironment. AU AqH can activate DC, leading to subsequent proliferation and activation of effector T cells. Thus, the AU microenvironment contributes to immune cell responses and intraocular inflammation.

IL-23R and IL-17A polymorphisms correlate with susceptibility of ankylosing spondylitis in a Southwest Chinese population

The association between the IL-23R and IL-17A polymorphisms and ankylosing spondylitis (AS) in the Southwest Chinese Population is still unclear. The purpose of this study is to detect the association between IL-23R and IL-17A polymorphisms and AS. A case-control study consisting of 486 AS patients and 480 healthy controls was performed. We used the high-resolution melting methods (HRM) to genotype five selected single nucleotide polymorphisms (SNPs), rs6693831, rs7517847, rs1884444, rs10889677 in the IL-23R gene and rs2275913 in the IL-17A gene. Meanwhile, the laboratory indexes were recorded. In this study, patients with genotype CC (p = 8.574E-8) and allele C (p = 3.206E-31) on SNP rs6693831 (IL-23R) showed decreased risk of AS. The genotype TT (p = 4.551E-6) and allele T (p = 0.02) on SNP rs1884444 (IL-23R) showed significant lower risk of AS. Individuals carrying the allele A of rs2275913 showed higher morbidity of AS (p = 0.04). We first detected that rs6693831 and rs1884444 in IL-23R gene and rs2275913 in IL-17A gene have genetic association with AS.

Genome-wide DNA methylation profile analysis identifies differentially methylated loci associated with ankylosis spondylitis

Background

Ankylosing spondylitis (AS) is a chronic rheumatic and autoimmune disease. Little is known about the potential role of DNA methylation in the pathogenesis of AS. This study was undertaken to explore the potential role of DNA methylation in the genetic mechanism of AS.

Methods

In this study, we compared the genome-wide DNA methylation profiles of peripheral blood mononuclear cells (PBMCs) between five AS patients and five healthy subjects, using the Illumina Infinium HumanMethylation450 BeadChip. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was performed to validate the relevance of the identified differentially methylated genes for AS, using another independent sample of five AS patients and five healthy subjects.

Results

Compared with healthy controls, we detected 1915 differentially methylated CpG sites mapped to 1214 genes. The HLA-DQB1 gene achieved the most significant signal (cg14323910, adjusted P = 1.84 × 10^–6, β difference = 0.5634) for AS. Additionally, the CpG site cg04777551 of HLA-DQB1 presented a suggestive association with AS (adjusted P = 1.46 × 10^–3, β difference = 0.3594). qRT-PCR observed that the mRNA expression level of HLA-DQB1 in AS PBMCs was significantly lower than that in healthy control PBMCs (ratio = 0.48 ± 0.10, P < 0.001). Gene Ontology (GO) and KEGG pathway enrichment analysis of differentially methylated genes identified four GO terms and 10 pathways for AS, functionally related to antigen dynamics and function.

Conclusions

Our results demonstrated the altered DNA methylation profile of AS and implicated HLA-DQB1 in the development of AS.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1382-1) contains supplementary material, which is available to authorized users.

Targeting the interleukin-23/17 axis in axial spondyloarthritis

PURPOSE OF REVIEW

This article highlights and emphasizes how new knowledge of mechanisms linked to the interleukin-23 (IL-23)/IL-17 pathway is relevant to the pathophysiology of axial spondyloarthritis (axSpA) and demonstrates how molecules in IL-23/IL-17 pathway provide novel therapeutic targets for axSpA patients.

RECENT FINDINGS

Similarly to ankylosing spondylitis (AS), the increased frequency of Th17 cells in nr-axSpA patients underscores the concept that these disorders can be viewed on a spectrum. Recent findings suggest that the contribution of IL-23/IL-17 signaling pathways possibly differs in male and female AS patients. The finding that IL-17 and IL-22 secreting-type 3 innate lymphoid cells are increased in AS patients point to their potential role in the pathogenesis of axSpA. Reports of dysbiosis in the gut microbiome of AS patients support previous work indicating a possible causal relationship between altered gut flora, ileocolonic inflammation and axSpA. Of important clinical relevance are results from clinical trials supporting the efficacy and safety of agents that block IL-12/23 (ustekinumab) and IL-17 (secukinumab and ixekizumab) in AS patients.

SUMMARY

Recent studies further establish the central position of the IL-23/IL-17 pathway in the pathogenesis of axSpA. Targeting the IL-23/IL-17 pathway appears to be a safe and effective strategy for treatment of axSpA patients.

A Possible Role of Intestinal Microbiota in the Pathogenesis of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the sacroiliac joints and the spine, for which the pathogenesis is thought to be a result of the combination of host genetic factors and environmental triggers. However, the precise factors that determine one’s susceptibility to AS remain to be unraveled. With 100 trillion bacteria residing in the mammalian gut having established a symbiotic relation with their host influencing many aspects of host metabolism, physiology, and immunity, a growing body of evidence suggests that intestinal microbiota may play an important role in AS. Several mechanisms have been suggested to explain the potential role of the microbiome in the etiology of AS, such as alterations of intestinal permeability, stimulation of immune responses, and molecular mimicry. In this review, the existing evidence for the involvement of the microbiome in AS pathogenesis was discussed and the potential of intestinal microbiome-targeting strategies in the prevention and treatment of AS was evaluated.