Ankylosing spondylitis monocyte-derived macrophages express increased level of A2A adenosine receptor and decreased level of ectonucleoside triphosphate diphosphohydrolase-1 (CD39), A1 and A2B adenosine receptors

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.

Role of adenosine A2a receptor in cancers and autoimmune diseases

Adenosine receptors are P1 class of purinergic receptors that belong to G protein-coupled receptors. There are 4 subtypes of adenosine receptors, namely A1, A2A, A2B, and A3. A2AR has a high affinity for the ligand adenosine. Under pathological conditions or external stimuli, ATP is sequentially hydrolyzed to adenosine by CD39 and CD73. The combination of adenosine and A2AR can increase the concentration of cAMP and activate a series of downstream signaling pathways, and further playing the role of immunosuppression and promotion of tumor invasion. A2AR is expressed to some extent on various immune cells, where it is abnormally expressed on immune cells in cancers and autoimmune diseases. A2AR expression also correlates with disease progression. Inhibitors and agonists of A2AR may be potential new strategies for treatment of cancers and autoimmune diseases. We herein briefly reviewed the expression and distribution of A2AR, adenosine/A2AR signaling pathway, expression, and potential as a therapeutic target.

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.

The role of adenosine A1 receptor on immune cells

BACKGROUND

Adenosine, acting as a regulator by mediating the activation of G protein-coupled adenosine receptor families (A₁, A₂A, A₂B, and A₃), plays an important role under physiological and pathological conditions. As the receptor with the highest affinity for adenosine, the role of adenosine A₁ receptor (A₁R)-mediated adenosine signaling pathway in the central nervous system has been well addressed. However, functions of A₁R on immune cells are less summarized. Considering that some immune cells express multiple types of adenosine receptors with distinct effects and varied density, exogenous adenosine of different concentrations may induce divergent immune cell functions.

MATERIALS AND METHODS

The literatures about the expression of A₁R and its regulation on immune cells and how it regulates the function of immune cells were searched on PubMed and Google Scholar.

CONCLUSION

In this review, we discussed the effects of A₁R on immune cells, including monocytes, macrophages, neutrophils, dendritic cells, and microglia, and focused on the role of A₁R in regulating immune cells in diseases, which may facilitate our understanding of the mechanisms by which adenosine affects immune cells through A₁R.

The serum uric acid is longitudinally related to patients global assessment of disease activity in male patients with axial spondyloarthritis

Objectives

To investigate longitudinal relationship between serum uric acid (SUA) and disease activity among Chinese males with axial spondyloarthritis (axSpA).

Methods

Two-year data from the NASA study cohort of male patients with axial spondyloarthritis were analyzed. Patients global assessment of disease activity (PtGA), BASDAI, ASDAS-CRP, BASFI, and SF-36 were used as the outcomes. The autoregressive Generalized Estimation Equation (GEE) model was used to investigate the longitudinal relationship between SUA and the above outcomes. Age and gender and symptom duration were tested as effect modifiers or confounders.

Results

In total, 102 male axSpA patients were included, 33.3% of who were hyperuricemia at baseline. Over time,serum uric acid levels associated with the global assessment of patient global assessment of disease activity (PtGA)[P=0.041, β=-2.059,95%CI(-4.032, -0.086)], SF-36: Vitality (VT) [P=0.01, β=1.751, 95%CI (0.415,3.087)], SF-36: Social Functioning (SF)[P=0.002, β= 2.968,95%CI (1.067,4.869)]). And these relationgships were independent of age, symptom duration, baseline uric acid levels, and medication use.

Conclusions

In summary, SUA levels is longitudinally related to PtGA and mental health assessment. Age, gender and symptom duration do not have an impact on the relationships.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05657-3.

Monocyte-derived and M1 macrophages from ankylosing spondylitis patients released higher TNF-α and expressed more IL1B in response to BzATP than macrophages from healthy subjects

Macrophages participate in the pathogenesis of ankylosing spondylitis (AS) by producing inflammatory cytokines. Extracellular adenosine triphosphate (eATP), released during cell stress, acts through purinergic receptors (P2XR and P2YR) and induces inflammatory responses. We investigated the effect of 2ʹ(3ʹ)-O-(4-benzoyl benzoyl) ATP (BzATP) (a prototypic agonist of P2X7R) on the production of inflammatory cytokines in both monocyte-generated (M2-like) and M1 macrophages from patients and controls. Macrophages were differentiated from isolated periphery-monocytes (n = 14 in each group) by macrophage colony-stimulating factor (M-CSF). Using LPS and IFN-γ, macrophages were skewed toward M1 type and were treated with BzATP. Gene expression and protein release of IL-1β, IL-23, and TNF-α were evaluated by real-time PCR and ELISA methods respectively before and after treatment. BzATP significantly increased the protein release of TNF-α and the expression of TNFA and IL1B in monocyte-generated macrophages. Besides, BzATP treatment significantly upregulated IL1B expression, reduced TNFA and IL23A expression, and TNF-α release in M1 macrophages from both groups. Monocyte-generated and M1 macrophages from AS patients released higher TNF-α and expressed more IL1B in response to the same concentration of BzATP treatment respectively. Based on our results, AS macrophages were more sensitive to BzATP treatment and responded more intensively. Besides, the diverse effects of BzATP on monocyte-derived and M1 macrophages in our study may represent the differed inflammatory properties of these two groups of macrophages in response to eATP in the body.

Surface AMP deaminase 2 as a novel regulator modifying extracellular adenine nucleotide metabolism

Adenine nucleotides represent crucial immunomodulators in the extracellular environment. The ectonucleotidases CD39 and CD73 are responsible for the sequential catabolism of ATP to adenosine via AMP, thus promoting an anti-inflammatory milieu induced by the "adenosine halo". AMPD2 intracellularly mediates AMP deamination to IMP, thereby both enhancing the degradation of inflammatory ATP and reducing the formation of anti-inflammatory adenosine. Here, we show that this enzyme is expressed on the surface of human immune cells and its predominance may modify inflammatory states by altering the extracellular milieu. Surface AMPD2 (eAMPD2) expression on monocytes was verified by immunoblot, surface biotinylation, mass spectrometry, and immunofluorescence microscopy. Flow cytometry revealed enhanced monocytic eAMPD2 expression after TLR stimulation. PBMCs from patients with rheumatoid arthritis displayed significantly higher levels of eAMPD2 expression compared with healthy controls. Furthermore, the product of AMPD2-IMP-exerted anti-inflammatory effects, while the levels of extracellular adenosine were not impaired by an increased eAMPD2 expression. In summary, our study identifies eAMPD2 as a novel regulator of the extracellular ATP-adenosine balance adding to the immunomodulatory CD39-CD73 system.

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.

Activation of adenosine A2A receptor induced interleukin-23 mRNA expression in macrophages of ankylosing spondylitis patients

BACKGROUND

Ankylosing spondylitis (AS) is an auto-inflammatory debilitating disorder with a complex pathogenesis. The adenosinergic pathway is an immunologic regulating pathway with a potential role in AS pathophysiology. In the present study, we have aimed to investigate the influence of A_2A adenosine receptor (A_2AAR) activation on tumor necrosis factor-α (TNF-α) and interleukin-23 (IL-23) expression and secretion by monocyte-generated macrophages of AS patients.

METHODS

Whole-blood separated monocytes were extracted from 14 AS patients and 14 healthy controls. Macrophages were differentiated by macrophage colony-stimulating factor (M-CSF), and surface markers were confirmed by flow cytometer. Cells were treated with CGS-21680 as a known agonist of A_2AAR. Analysis of ADORA2A, TNFA, and IL23A gene expression was performed by SYBR green real-time PCR. The concentration of secreted cytokines was also measured by ELISA kits.

RESULTS

Based on our analysis, CGS-21680 significantly decreased TNF-α secretion by monocyte-derived macrophages of AS patients. Moreover, A_2AAR agonist increased the IL23A mRNA expression level in monocyte-derived macrophages of AS patients considerably. Whereas, CGS-21680 did not have any influence on macrophages of healthy individuals.

CONCLUSION

According to our results, it appears that A_2AAR activation can increase IL-23 secretion by monocyte-derived macrophages of AS patients. Although the TNF-α reducing effect of A_2AAR agonists can be a potential target in AS treatment, robust increasing of IL-23 should be considered as the undesirable effect of these agents.

P2 receptors mRNA expression profiles in macrophages from ankylosing spondylitis patients and healthy individuals

BACKGROUND

Ankylosing spondylitis (AS) is a multifactorial rheumatic disease which mainly involves the axial skeleton. Macrophages and extracellular nucleotides have been shown to contribute to the inflammation process in autoimmune diseases. Membrane-bound purinergic P2 receptors might be involved in the modulation of immune cells in AS. Therefore, we aimed to analyze the messenger RNA (mRNA) expression of P2 receptors in the macrophages of AS patients and healthy controls.

METHODS

Twenty-three AS patients and 23 age- and sex-matched healthy individuals were included in our study. Whole blood-separated monocytes of study participants were stimulated by macrophage colony-stimulating factor for 7 days and differentiated to macrophages. Monocyte and macrophage markers were analyzed by flow cytometry. SYBR green real-time polymerase chain reaction was used to measure the relative expression levels of P2RX₁ , P2RX₂ , P2RX₃ , P2RX₄ , P2RX₅ , P2RX₆ , P2RX₇ , P2RY₁ , P2RY₂ , P2RY₄ , P2RY₆ , P2RY₁₁ , P2RY₁₂ , P2RY₁₃ , P2RY₁₄ , and PANX1 genes.

RESULTS

P2RY₁₃ and P2RY₆ genes had the highest expression levels in macrophages among P2RY genes. P2RY₁ mRNA expression was significantly down-regulated (-1.75 fold) and P2RY₁₄ was up-regulated (2.6 fold) in macrophages of AS patients compared to healthy individuals. P2RX₄ gene had the highest expression in monocyte-derived macrophages, followed by P2RX₇ and P2RX₁  genes. There was no significant difference in P2X receptor mRNA expression level between macrophages of AS patients and healthy individuals.

CONCLUSIONS

Our results indicate that AS patients show altered expression levels of P2 receptor genes. Moreover, these changes might be associated with disease activity and patients' status.

Expression and Metabolomic Profiling in Axial Spondyloarthritis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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