Macrophage phenotype in the subclinical gut inflammation of patients with ankylosing spondylitis

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.

Increased gut permeability and intestinal inflammation precede arthritis onset in the adjuvant-induced model of arthritis

BACKGROUND

Intestinal inflammation, dysbiosis, intestinal permeability (IP), and bacterial translocation (BT) have been identified in patients with spondyloarthritis but the time at which they appear and their contribution to the pathogenesis of the disease is still a matter of debate.

OBJECTIVES

To study the time-course of intestinal inflammation (I-Inf), IP, microbiota modification BT in a rat model of reactive arthritis, the adjuvant-induced arthritis model (AIA).

METHODS

Analysis was performed at 3 phases of arthritis in control and AIA rats: preclinical phase (day 4), onset phase (day 11), and acute phase (day 28). IP was assessed by measuring levels of zonulin and ileal mRNA expression of zonulin. I-inf was assessed by lymphocyte count from rat ileum and by measuring ileal mRNA expression of proinflammatory cytokines. The integrity of the intestinal barrier was evaluated by levels of iFABP. BT and gut microbiota were assessed by LPS, soluble CD14 levels, and 16S RNA sequencing in mesenteric lymph node and by 16S rRNA sequencing in stool, respectively.

RESULTS

Plasma zonulin levels increased at the preclinical and onset phase in the AIA group. Plasma levels of iFABP were increased in AIA rats at all stages of the arthritis course. The preclinical phase was characterized by a transient dysbiosis and increased mRNA ileal expression of IL-8, IL-33, and IL-17. At the onset phase, TNF-α, IL-23p19, and IL-8 mRNA expression were increased. No changes in cytokines mRNA expression were observed at the acute phase. Increased CD4⁺ and CD8⁺ T cell number was measured in the AIA ileum at day 4 and day 11. No increase in BT was observed.

CONCLUSION

These data show that intestinal changes precede the development of arthritis but argue against a strict "correlative" model in which arthritis and gut changes are inseparable.

Prostaglandin E2/EP4 axis is upregulated in Spondyloarthritis and contributes to radiographic progression

Ankylosing spondylitis (AS) is an inflammatory disease leading to spine ankylosis; however, the mechanisms behind new bone formation are still not fully understood. Single Nucleotide Polymorphisms (SNPs) in PTGER4, encoding for the receptor EP4 of prostaglandin E2 (PGE2), are associated with AS. Since the PGE2-EP4 axis participates in inflammation and bone metabolism, this work aims at investigating the influence of the prostaglandin-E2 axis on radiographic progression in AS. In 185 AS (97 progressors), baseline serum PGE2 predicted progression, and PTGER4 SNP rs6896969 was more frequent in progressors. Increased EP4/PTGER4 expression was observed in AS circulating immune cells, synovial tissue, and bone marrow. CD14highEP4 + cells frequency correlated with disease activity, and when monocytes were cocultured with mesenchymal stem cells, the PGE2/EP4 axis induced bone formation. In conclusion, the Prostaglandin E2 axis is involved in bone remodelling and may contribute to the radiographic progression in AS due to genetic and environmental upregulation.

Joint together: The etiology and pathogenesis of ankylosing spondylitis

Spondyloarthritis (SpA) refers to a group of diseases with inflammation in joints and spines. In this family, ankylosing spondylitis (AS) is a rare but classic form that mainly involves the spine and sacroiliac joint, leading to the loss of flexibility and fusion of the spine. Compared to other diseases in SpA, AS has a very distinct hereditary disposition and pattern of involvement, and several hypotheses about its etiopathogenesis have been proposed. In spite of significant advances made in Th17 dynamics and AS treatment, the underlying mechanism remains concealed. To this end, we covered several topics, including the nature of the immune response, the microenvironment in the articulation that is behind the disease's progression, and the split between the hypotheses and the evidence on how the intestine affects arthritis. In this review, we describe the current findings of AS and SpA, with the aim of providing an integrated view of the initiation of inflammation and the development of the disease.

Role of macrophage-associated chemokines in the assessment of initial axial spondyloarthritis

OBJECTIVES

To identify biomarkers that reflect disease activity scores and to investigate the role of macrophage-associated chemokines in initial axial spondyloarthritis (axSpA).

METHOD

Patients with axSpA were enrolled. The SpondyloArthritis Research Consortium of Canada (SPARCC) method was used to score bone marrow oedema (BMO) in the inflammatory lesions on magnetic resonance imaging (MRI). Radiographic assessment of the spine was performed using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Clinical variables, including inflammatory markers, serum CC chemokine ligand 2 (CCL2), CCL3, CCL7, CCL8 and C-X3-C motif ligand 1 (CX3CL1), were measured. Correlation analysis between serum levels of these macrophage-associated chemokines and clinical data was performed.

RESULTS

There were no significant differences between the axSpA group and the healthy control group in terms of serum levels of CCL2, CCL3 or CCL8. Compared to the healthy control group, the serum levels of CCL7 and CX3CL1 were significantly higher in ankylosing spondylitis (AS) (p = 0.045, p = 0.017, respectively). In the AS subgroup, the serum level of CX3CL1 had a positive correlation with SPARCC scores.

CONCLUSIONS

In AS, serum CCL7 and CX3CL1 levels are elevated. The serum level of CX3CL1 is associated with MRI-determined oedema in AS. CX3CL1 may be useful as a biomarker to predict active inflammation in the sacroiliac joint (SIJ) in AS. Key Points • Serum levels of CX3CL1 are associated with MRI-determined oedema in AS. • CX3CL1 may be a useful biomarker to predict active inflammation in the sacroiliac joint in AS.

Long-Term Environmental Hypoxia Exposure and Haematopoietic Prolyl Hydroxylase-1 Deletion Do Not Impact Experimental Crohn's Like Ileitis

Simple Summary

Hypoxia-induced signalling represents an important contributor to inflammatory bowel disease (IBD) pathophysiology. However, available data solely focus on colonic inflammation while the primary disease location in Crohn’s disease patients is the terminal ileum. Therefore, we explored the effects of environmental hypoxia and immune cell-specific deletion of oxygen sensor prolyl hydroxylase (PHD) 1 in a Crohn’s like ileitis mouse model. Five-week-old TNF^∆ARE/+ mice and wildtype (WT) littermates were housed in normoxia (21% O₂) or hypoxia (8% O₂) for 10 weeks. Although environmental hypoxia increased both systemic as ileal markers of hypoxia, the body weight evolution in both WT and TNF^∆ARE/+ mice was not affected. Interestingly, hypoxia did increase circulatory monocytes, ileal mononuclear phagocytes and proinflammatory cytokine expression in WT mice. However, no histological or inflammatory gene expression differences in the ileum could be identified between TNF^∆ARE/+ mice housed in hypoxia versus normoxia nor between TNF^∆ARE/+ and WT mice with additional loss of immune cell-specific Phd1 expression. This is the first study showing that long-term environmental hypoxia or haematopoietic Phd1-deletion does not impact experimental ileitis. Therefore, it strongly questions whether targeting hypoxia-induced signalling via currently available PHD inhibitors would exert an immune suppressive effect in IBD patients with ileal inflammation.

Abstract

Environmental hypoxia and hypoxia-induced signalling in the gut influence inflammatory bowel disease pathogenesis, however data is limited to colitis. Hence, we investigated the effect of environmental hypoxia and immune cell-specific deletion of oxygen sensor prolyl hydroxylase (PHD) 1 in a Crohn’s like ileitis mouse model. Therefore, 5-week-old C57/BL6 TNF^∆ARE/+ mice and wildtype (WT) littermates were housed in normoxia (21% O₂) or hypoxia (8% O₂) for 10 weeks. Systemic inflammation was assessed by haematology. Distal ileal hypoxia was evaluated by pimonidazole staining. The ileitis degree was scored on histology, characterized via qPCR and validated in haematopoietic Phd1-deficient TNF^∆ARE/+ mice. Our results demonstrated that hypoxia did not impact body weight evolution in WT and TNF^∆ARE/+ mice. Hypoxia increased red blood cell count, haemoglobin, haematocrit and increased pimonidazole intensity in the ileum. Interestingly, hypoxia evoked an increase in circulatory monocytes, ileal mononuclear phagocytes and proinflammatory cytokine expression in WT mice. Despite these alterations, no histological or ileal gene expression differences could be identified between TNF^∆ARE/+ mice housed in hypoxia versus normoxia nor between haematopoietic Phd1-deficient TNF^∆ARE/+ and their WT counterparts. Therefore, we demonstrated for the first time that long-term environmental hypoxia or haematopoietic Phd1-deletion does not impact experimental ileitis development.

Influence of IL10 (rs1800896) Polymorphism and TNF-α, IL-10, IL-17A, and IL-17F Serum Levels in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic autoimmune inflammatory disease that mainly affects the axial and sacroiliac joints. Single-nucleotide polymorphisms (SNPs) in genes encoding cytokines have been associated with AS, which can interfere with the production of these cytokines and contribute to the development of AS. In order to contribute to a better understanding of the pathology of AS, our objective was to investigate a possible association of the IL10 −1082 A>G SNP (rs1800896) with AS and to evaluate the serum levels of TNF-α, IL-10, IL-17A, and IL-17F in AS patients and controls comparing them with their respective genotypes (TNF rs1800629, IL10 rs1800896, IL17A rs2275913, and IL17F rs763780). Patients and controls were selected from the Maringá University Hospital and the Maringá Rheumatism Clinic, in Paraná State, Southern Brazil, and they were diagnosed by the ASAS Criteria. In total, 149 patients and 169 controls were genotyped for the IL10 −1082 A>G polymorphism using a polymerase chain reaction with sequence specific primers (PCR-SSP); the measurement of TNF-α serum levels was performed through the immunofluorimetric test and IL-10, IL-17A, and IL-17F using an ELISA test. There was a high frequency of the IL10 −1082 G allele in AS patients compared with controls with an odds ratio of 1.83 and 95% confidence interval of 1.32 to 2.54, and a significant difference in the genotype frequencies of the IL10 −1082 A/G+G/G between patients and healthy controls, with an odds ratio of 3.01 and 95% confidence interval of 1.75 to 5.17. In addition, increased serum levels of IL-10 were observed in AS patients: 2.38 (IQR, 0.91) pg/ml compared with controls 1.72 (IQR 0.93) pg/ml (P = 0.01). Our results also showed an association between IL17F rs763780 C/T+T/T genotypes and increased serum levels of IL-17F in patients with AS and also in controls. We can conclude that patients with the A/G and G/G genotypes for −1082 A>G (rs1800896) in the IL10 gene are three times more likely to develop AS, that the serum level of IL-10 was higher in AS patients and that the IL17F rs763780 polymorphism can affect the levels of IL-17F in the serum of patients and controls in the same way.

Ankylosing spondylitis: an autoimmune or autoinflammatory disease?

Ankylosing spondylitis (AS) is a chronic inflammatory disorder of unknown aetiology. Unlike other systemic autoimmune diseases, in AS, the innate immune system has a dominant role characterized by aberrant activity of innate and innate-like immune cells, including γδ T cells, group 3 innate lymphoid cells, neutrophils, mucosal-associated invariant T cells and mast cells, at sites predisposed to the disease. The intestine is involved in disease manifestations, as it is at the forefront of the interaction between the mucosal-associated immune cells and the intestinal microbiota. Similarly, biomechanical factors, such as entheseal micro-trauma, might also be involved in the pathogenesis of the articular manifestation of AS, and sentinel immune cells located in the entheses could provide links between local damage, genetic predisposition and the development of chronic inflammation. Although these elements might support the autoinflammatory nature of AS, studies demonstrating the presence of autoantibodies (such as anti-CD74, anti-sclerostin and anti-noggin antibodies) and evidence of activation and clonal expansion of T cell populations support an autoimmune component to the disease. This Review presents the evidence for autoinflammation and the evidence for autoimmunity in AS and, by discussing the pathophysiological factors associated with each, aims to reconcile the two hypotheses.

Haptoglobin and Its Related Protein, Zonulin-What Is Their Role in Spondyloarthropathy?

Haptoglobin (Hp) is an acute phase protein which supports the immune response and protects tissues from free radicals. Its concentration correlates with disease activity in spondyloarthropathies (SpAs). The Hp polymorphism determines the functional differences between Hp1 and Hp2 protein products. The role of the Hp polymorphism has been demonstrated in many diseases. In particular, the Hp 2-2 phenotype has been associated with the unfavorable course of some inflammatory and autoimmune disorders. Its potential role in modulating the immune system in SpA is still unknown. This article contains pathophysiological considerations on the potential relationship between Hp, its polymorphism and SpA.

The gut-joint axis in spondyloarthritis: immunological, microbial, and clinical insights

The strong genetic and clinical overlaps between spondyloarthritis (SpA) and inflammatory bowel disease (IBD) have placed much needed focus on the gut-joint axis of inflammation in SpA, leading to three key hypotheses that attempt to unravel this complex relationship. The arthritogenic peptide hypothesis and the aberrant cellular trafficking hypothesis have been put forth to rationalize the manner by which the innate and adaptive immune systems cooperate and converge during SpA pathogenesis. The bacterial dysbiosis hypothesis discusses how changes in the microbiome lead to architectural and immunological consequences in SpA. These theories are not mutually exclusive, but can provide an explanation as to why subclinical gut inflammation may sometimes precede joint inflammation in SpA patients, thereby implying a causal relationship. Such investigations will be important in informing therapeutic decisions which may be common to both SpA and IBD. However, these hypotheses can also offer insights for a coincident inflammatory relationship between the gut and the joint, particularly when assessing the immunological players involved. Insights from understanding how these systems might affect the gut and joint differently will be equally imperative to address where the therapeutic differences lie between the two diseases. Collectively, this knowledge has practical implications in predicting the likelihood of IBD development in SpA or presence of coincident SpA-IBD, uncovering novel therapeutic targets, and redesigning currently approved treatments. It is evident that a multidisciplinary approach between the rheumatology and gastroenterology fields cannot be ignored, when it comes to the care of SpA patients at risk of IBD or vice versa.

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.

Revisiting the gut-joint axis: links between gut inflammation and spondyloarthritis

Gut inflammation is strongly associated with spondyloarthritis (SpA), as exemplified by the high prevalence of inflammatory bowel disease (IBD) and the even higher occurrence of subclinical gut inflammation in patients with SpA. The gut-joint axis of inflammation in SpA is further reinforced by similarities in immunopathogenesis at both anatomical sites and by the clinical success of therapies blocking TNF and IL-23 in IBD and in some forms of SpA. Many genetic risk factors are shared between SpA and IBD, and changes in the composition of gut microbiota are seen in both diseases. Current dogma is that inflammation in SpA initiates in the gut and leads to joint inflammation; however, although conceptually attractive, some research does not support this causal relationship. For example, therapies targeting IL-17A are efficacious in the joint but not the gut, and interfering with gut trafficking by targeting molecules such as α4β7 in IBD can lead to onset or flares of SpA. Several important knowledge gaps remain that must be addressed in future studies. Determining the true nature of the gut-joint axis has real-world implications for the treatment of patients with co-incident IBD and SpA and for the repurposing of therapeutics from one disease to the other.

GM-CSF drives dysregulated hematopoietic stem cell activity and pathogenic extramedullary myelopoiesis in experimental spondyloarthritis

Dysregulated hematopoiesis occurs in several chronic inflammatory diseases, but it remains unclear how hematopoietic stem cells (HSCs) in the bone marrow (BM) sense peripheral inflammation and contribute to tissue damage in arthritis. Here, we show the HSC gene expression program is biased toward myelopoiesis and differentiation skewed toward granulocyte-monocyte progenitors (GMP) during joint and intestinal inflammation in experimental spondyloarthritis (SpA). GM-CSF-receptor is increased on HSCs and multipotent progenitors, favoring a striking increase in myelopoiesis at the earliest hematopoietic stages. GMP accumulate in the BM in SpA and, unexpectedly, at extramedullary sites: in the inflamed joints and spleen. Furthermore, we show that GM-CSF promotes extramedullary myelopoiesis, tissue-toxic neutrophil accumulation in target organs, and GM-CSF prophylactic or therapeutic blockade substantially decreases SpA severity. Surprisingly, besides CD4+ T cells and innate lymphoid cells, mast cells are a source of GM-CSF in this model, and its pathogenic production is promoted by the alarmin IL-33.

The Pathogenesis of Ankylosing Spondylitis: an Update

PURPOSE OF REVIEW

Ankylosing spondyloarthritis (AS) is a chronic inflammatory disease that involves the axial joints and entheses. Extra-spinal manifestations such as anterior uveitis, psoriasis, and colitis also occur frequently. This review on the pathogenesis of AS includes an update on the recent discoveries within the field.

RECENT FINDINGS

HLA-B*27 is still considered of major importance in the pathogenesis, and it has recently been shown to profoundly affect the gut microbiome and its metabolites and the handling of bacteria during infection. Biochemical and biophysical properties of HLA-B*27 influence its ability to misfold, to induce an endoplasmic reticulum stress response, and to promote autophagy/unfolded protein responses (UPR). HLA-B*27 free heavy chains may induce inflammation through T cells, NK cells, and myeloid cells. Induction of UPR genes results in release of tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), IL-23, and interferon-γ and increase in T helper (Th) 17 cells. Several other HLA-B and non-B molecules have been associated with AS, although their role in the pathogenesis is unknown. Genotypes of endoplasmic reticulum aminopeptidases (ERAP) 1 and 2 have been associated with alterations in the antigenic pool expressed by HLA-B*27 molecules. In the gut, innate immune cells type 3 (ILC3) influence T cell expression of IL-17 and IL-22. Gamma-delta (γ/δ) T cells are induced by IL-23 to produce IL-17. IL-7 induces mucosa-associated invariant T (MAIT) cells to produce IL-17. Besides the microbiome, zonulin may be important through its effects on the permeability of tight junctions in the intestinal epithelial barrier.

Proinflammatory CX3CR1+CD59+Tumor Necrosis Factor-Like Molecule 1A+Interleukin-23+ Monocytes Are Expanded in Patients With Ankylosing Spondylitis and Modulate Innate Lymphoid Cell 3 Immune Functions

OBJECTIVE

Gut-derived innate lymphoid cell 3 (ILC3) has been shown to participate in the pathogenesis of ankylosing spondylitis (AS). CX₃ CR1+ mononuclear phagocytes (MNPs) have been demonstrated to modulate ILC3 function in the gut. This study was undertaken to investigate the role of proinflammatory CX₃ CR1+CD59+ MNPs in modulating ILC3 function in AS patients.

METHODS

MNP subsets in the blood of AS patients and controls were analyzed by flow cytometry. The presence of CX₃ CR1+CD59+ cells in tissue was confirmed by confocal microscopy. Expression of the proinflammatory chemokines CX₃ CL1 and CCL2 and decoy receptor 6 (DcR-6) was analyzed. Peripheral CX₃ CR1+CD59+ cells were cocultured with ILC3, and changes in their frequency were evaluated by flow cytometry. Transcriptome analysis of circulating CX₃ CR1+ monocytes was also performed.

RESULTS

DcR-6 deficiency and CCL2 overexpression were observed in inflamed tissues from AS patients. In the gut, the proinflammatory CX₃ CR1+CD59+ MNP population was expanded, correlated with the presence of bacteria, and produced high levels of tumor necrosis factor-like molecule 1A (TL1A) and interleukin-23 (IL-23). MNPs positive for CD11b, CD11c, and major histocompatibility complex class II, predominantly expressing CX₃ CR1, were also expanded in the small intestines of treatment-naive SKG relative to BALB/c mice. The frequency of gut-derived CX₃ CR1+CD59+CCR9+TL1A+IL-23+ MNPs was significantly higher in the peripheral blood and synovial fluid of AS patients than controls. CCR9+CX₃ CR1+CD59+ monocytes were also expanded in AS synovial and bone marrow samples. Transcriptome analysis of isolated CX₃ CR1+CD59+ monocytes demonstrated a specific proinflammatory profile in AS. Isolated proinflammatory CX₃ CR1+CD59+ MNPs from AS patients induced the expansion and activation of ILC3.

CONCLUSION

Proinflammatory CX₃ CR1+CD59+TL1A+IL-23+ MNPs are expanded in AS patients and display a specific proinflammatory transcriptome profile. Given the ability of these cells to support ILC3 expansion, they may promote a sustained proinflammatory status in AS.

Deregulation of microRNA expression in monocytes and CD4+ T lymphocytes from patients with axial spondyloarthritis

Background

MicroRNAs (MiRs) play an important role in the pathogenesis of chronic inflammatory diseases. This study is the first to investigate miR expression profiles in purified CD4⁺ T lymphocytes and CD14⁺ monocytes from patients with axial spondyloarthritis (axSpA) using a high-throughput qPCR approach.

Methods

A total of 81 axSpA patients fulfilling the 2009 ASAS classification criteria, and 55 controls were recruited from October 2014 to July 2017. CD14⁺ monocytes and CD4⁺ T lymphocytes were isolated from peripheral blood mononuclear cells. MiR expression was investigated by qPCR using the Exiqon Human MiRnome panel I analyzing 372 miRNAs. Differentially expressed miRNAs identified in the discovery cohort were validated in the replication cohort.

Results

We found a major difference in miR expression patterns between T lymphocytes and monocytes regardless of the patient or control status. Comparing disease-specific differentially expressed miRs, 13 miRs were found consistently deregulated in CD14⁺ cells in both cohorts with miR-361-3p, miR-223-3p, miR-484, and miR-16-5p being the most differentially expressed. In CD4⁺ T cells, 11 miRs were differentially expressed between patients and controls with miR-16-1-3p, miR-28-5p, miR-199a-5p, and miR-126-3p were the most strongly upregulated miRs among patients. These miRs are involved in disease relevant pathways such as inflammation, intestinal permeability or bone formation. Mir-146a-5p levels correlated inversely with the degree of inflammation in axSpA patients.

Conclusions

We demonstrate a consistent deregulation of miRs in both monocytes and CD4⁺ T cells from axSpA patients, which could contribute to the pathophysiology of the disease with potential interest from a therapeutic perspective.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1829-7) contains supplementary material, which is available to authorized users.

Evidence for M2 macrophage activation in patients with enthesitis-related arthritis category of juvenile idiopathic arthritis

Recently, an increase in CD163⁺ macrophages in ileal biopsies from ankylosing spondylitis patients and an increase in intermediate monocytes in enthesitis-related arthritis (ERA) have been reported. Thus, we studied sCD163 levels as M2 macrophage marker in serum and synovial fluid (SF) of ERA children and CD163 expression on monocyte subsets. Serum samples from ERA patients and healthy controls (HC) were assayed for sCD163 (ELISA). Serum and SF from ERA patients were analyzed when available from same patient (paired samples). In 10 patients, the CD163 expression level was analyzed on monocyte subsets by flow cytometry. Results are expressed as median (interquartile range (IQR)). Sera from 85 patients, SF from 32 ERA patients, and serum from 46 HC were analyzed. The average age at inclusion was 16 ± 3.24 years and age at onset was 11.2 ± 2.79 years. Seventy-nine of them were boys and HLA-B27 was positive in 64/80 patients. The median serum sCD163 levels were higher in patients [1080 (1305.2) ng/ml] than HC [780 (812.5) ng/ml; p < 0.001]. The SF levels [9000 (1250) ng/ml] were much higher than serum [3800 (3287.66) ng/ml; p < 0.001]. Disease activity data was available in 56 patients. Mean tender joint count was 2 (3), swollen joint count was 2 (2), ESR was 70 (65) mm and CRP was 7.1 (8.9) mg/dl. Serum sCD163 levels correlated with SF but not with disease activity. Intermediate monocytes (CD14⁺CD16⁺) from ERA patients had higher CD163 expression than HC. Elevated sCD163 levels in ERA patient's sera and even higher levels in paired SF suggest towards activation of alternatively activated macrophages in ERA. Lack of correlation with activity may suggest that they have an immune-regulatory role in ERA.

Changes in duodenal CD163-positive cells in dogs with chronic enteropathy after successful treatment

Chronic enteropathy (CE) in dogs is characterized retrospectively per treatment response as food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE) - the latter most resembling inflammatory bowel disease in people. The aim of this study was to characterize duodenal macrophages (Mϕ) in CE using immunohistochemistry; with calprotectin (CAL) as a marker of early differentiated Mϕ and CD163 expression as a marker for resident Mϕ in the duodenum before and after treatment. Prior to treatment, dogs with FRE and IRE had a lower CD163⁺/CAL⁺ ratio than control dogs (CTRL) in crypts; this increased significantly and normalized compared with CTRL after treatment. Conversely, the CD163⁺/CAL⁺ ratio in dogs with ARE was comparable to that in healthy dogs before and after treatment. In summary, these results suggest that Mϕ play a role in the pathogenesis of CE in FRE and IRE, with a decrease in resident Mϕ and an increase in early differentiated Mϕ, but not in ARE dogs. Mϕ normalize after successful treatment.

Role of Stem Cells in Pathophysiology and Therapy of Spondyloarthropathies-New Therapeutic Possibilities?

Considerable progress has been made recently in understanding the complex pathogenesis and treatment of spondyloarthropathies (SpA). Currently, along with traditional disease modifying anti-rheumatic drugs (DMARDs), TNF-α, IL-12/23 and IL-17 are available for treatment of such diseases as ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Although they adequately control inflammatory symptoms, they do not affect the abnormal bone formation processes associated with SpA. However, the traditional therapeutic approach does not cover the regenerative treatment of damaged tissues. In this regards, stem cells may offer a promising, safe and effective therapeutic option. The aim of this paper is to present the role of mesenchymal stromal cells (MSC) in pathogenesis of SpA and to highlight the opportunities for using stem cells in regenerative processes and in the treatment of inflammatory changes in articular structures.

M2 polarization of monocytes in ankylosing spondylitis and relationship with inflammation and structural damage

The aim of this study was to evaluate the polarization of peripheral blood monocytes in the patients with ankylosing spondylitis (AS) and to determine the correlations between monocyte polarization and inflammation and structural damage. A total of 120 AS patients, 50 rheumatoid arthritis (RA) patients and 100 healthy controls were enrolled in the study. M1 (CD68+CD192+) and M2 (CX3CR1+CD163+) monocytes were characterized by flow cytometry. Demographic, clinical, radiographic and laboratory data were collected and analyzed. A large increase in M2 (CX3CR1+CD163+) monocytes was observed in AS, and M2/M1 ratio was 7.18 ± 6.12, 2.54 ± 3.14 and 35.61 ± 20.04 in control, RA and AS, respectively. The M2/M1 ratio correlated with modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) (r = 0.565; p < 0.001), ESR (r = -0.321; p < 0.001, CRP (r = -0.265; p < 0.001) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (r = -0.201; p = 0.028). Anti-TNF-α therapy induced a significant reduction in the percentage of M1 monocyte, ESR, CRP and BASDAI in AS patients. The present results demonstrated that M2 type polarized monocytes are predominant in the peripheral blood in AS and the M2/M1 ratio is correlated with structural damage (mSASSS), inflammatory biomarkers (ESR and CRP) and BASDAI.

Correlation of the expression of miR-146a in peripheral blood mononuclear cells of patients with ankylosing spondylitis and inflammatory factors

We investigated the expression of miR-146a in peripheral blood mononuclear cell (PBMC) of patients with ankylosing spondylitis (AS) and its correlation with inflammatory factors to explore the clinical significance. In total 45 patients with AS were selected at the Weifang People's Hospital from June, 2014 to January, 2016. At the same time, 30 healthy volunteers were also selected to serve as control group. Expression level of miR-146a in PBMC cells of patients in each group was detected by quantitative real-time-polymerase chain reaction (qRT-PCR). Levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 in serum and the supernatant of culture medium of PBMC derived from each group were detected by enzyme-linked immunosorbent assay (ELISA). Correlations between expression level of miR-146a and serum inflammatory factors, and clinical indicators were analyzed. Clinical indicators included bath ankylosing spondylitis disease activity index (BASDAI), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and duration of morning stiffness. Expression level of miR-146a in PBMC of AS patients was significantly higher than that of healthy control (P<0.01); levels of TNF-α, IL-1β and IL-6 in serum and the supernatant of culture medium of PBMC derived from AS patients were significant compared to those of control group (P<0.01); expression of miR-146a in PBMC of patients with AS was positively correlated with the levels of TNF-α, IL-1β and IL-6 in serum (r=0.632, P<0.01; r=0.574, P<0.01; r=0.483, P<0.01). In addition, expression level of miR-146a in PBMC of patients with AS was positively correlated with BASDAI, ESR, CRP and duration of morning stiffness (r=0.551, P<0.01; r=0.738, P<0.01; r=0.685, P<0.01; r=0.497, P<0.01). Expression level of miR-146a in PBMC of AS patients was significantly increased and the expression level was positively correlated with the levels of TNF-α, IL-1β and IL-6 in serum (P<0.05). In addition, expression level of miR-146a in PBMC of AS patients was also positively correlated with BASDAI, ESR, CRP and duration of morning stiffness. Those results suggest that miR-146a may be involved in the pathogenesis of AS, and the expression level of miR-146a in PBMC cells may be helpful for diagnosis of AS and judgment of disease activity.

M1 and M2 macrophages' clinicopathological significance in cutaneous melanoma

Skin malignant melanoma (MM) is an aggressive cancer with an increasing incidence with limited therapies in advanced stages. Tumor-associated macrophages (TAMs) are the major immune constituent of the MM microenvironment and contribute toward its prognosis. TAMs' characterization and localization in human cancer is important to understand cancer progression and to identify molecular personalized therapies. M2 TAMs in stage I-II MMs are associated with worse prognostic parameters. A comprehensive M1-macrophage and M2-macrophage intratumoral localization and quantification in all stages of skin MMs is documented here with its clinical significance. To highlight immune pathways and possible early indicators of MM progression, we evaluated the number of M1 and M2 TAMs and intratumoral distribution in a large series of skin MMs. CD68 double immunostaining with MRP8-14 or inducible nitric oxide synthase (M1 macrophages) and with CD163 or CD204 (M2 macrophages) was performed in 94 stage I-IV skin MMs with a long duration of follow-up. The accumulation and distribution of M1 and M2 TAMs in intratumoral nests, stroma, and at the invasive front was correlated with clinicopathological variables. Since the early stage of MMs, M1 intratumoral macrophages were fewer than the M2 population; their recruitment was rapidly and progressively overwhelmed by an increase in M2 TAMs during MM progression. Independent of their intratumoral distribution, the accumulation of both M1 and M2 TAMs is associated with poor prognostic indicators and patients' survival. M1-recruited macrophages shift to the M2 phenotype early in MM development, possibly induced by high inducible nitric oxide synthase intratumoral increase peculiarly occurring since the initial MM stages. M2-recruited TAMs overwhelm M1 accumulation in all stages of MM progression, thus favoring neoplastic growth and dissemination. Independent of their intratumoral distribution, the prevalent accumulation of M2 TAMs in MM is statistically confirmed to be a poor indicator of patients' outcome and a potential target of immune therapies.

Dual polarization of human alveolar macrophages progressively increases with smoking and COPD severity

Background

It is known that tissue macrophages derive not only from blood monocytes but also from yolk sac or fetal liver, and the tissue of residence guides their function. When isolated, they lose tissue specific signatures, hence studies of human macrophages should be ideally done directly in the tissue. The aim of this study was to investigate directly in human lung tissue the polarization of alveolar macrophage (AM), classic (M1) or alternative (M2), in health and disease, using COPD as a model.

Methods

Surgical lungs from 53 subjects were studied: 36 smokers whose FEV₁ varied from normal to severe COPD, 11 non-smokers and 6 normal donors. iNOS and CD206 immunohistochemistry was used to quantify the percentage of AM polarized as M1 or M2 in lung sections.

Results and Discussion

The percentage of M1 and M2 increased progressively with smoking and COPD severity, from 26% to 84% for M1 and from 7% to 78% for M2. In donors 74% of AM were negative for M1 and 93% for M2. Confocal microscopy showed co-localization of M1 and M2 in the same AM in severe COPD.

Conclusion

In normal lungs alveolar macrophages were mostly non-polarized. With smoking and COPD severity, M1 and M2 polarization increased significantly and so did the co-expression of M1 and M2 in the same alveolar macrophage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0522-0) contains supplementary material, which is available to authorized users.

Dysbiosis and zonulin upregulation alter gut epithelial and vascular barriers in patients with ankylosing spondylitis

BACKGROUND

Dysbiosis has been recently demonstrated in patients with ankylosing spondylitis (AS) but its implications in the modulation of intestinal immune responses have never been studied. The aim of this study was to investigate the role of ileal bacteria in modulating local and systemic immune responses in AS.

METHODS

Ileal biopsies were obtained from 50 HLA-B27⁺ patients with AS and 20 normal subjects. Silver stain was used to visualise bacteria. Ileal expression of tight and adherens junction proteins was investigated by TaqMan real-time (RT)-PCR and immunohistochemistry. Serum levels of lipopolysaccharide (LPS), LPS-binding protein (LPS-BP), intestinal fatty acid-BP (iFABP) and zonulin were assayed by ELISA. Monocyte immunological functions were studied in in vitro experiments. In addition the effects of antibiotics on tight junctions in human leukocyte antigen (HLA)-B27 transgenic (TG) rats were assessed.

RESULTS

Adherent and invasive bacteria were observed in the gut of patients with AS with the bacterial scores significantly correlated with gut inflammation. Impairment of the gut vascular barrier (GVB) was also present in AS, accompanied by significant upregulation of zonulin, and associated with high serum levels of LPS, LPS-BP, iFABP and zonulin. In in vitro studies zonulin altered endothelial tight junctions while its epithelial release was modulated by isolated AS ileal bacteria. AS circulating monocytes displayed an anergic phenotype partially restored by ex vivo stimulation with LPS+sCD14 and their stimulation with recombinant zonulin induced a clear M2 phenotype. Antibiotics restored tight junction function in HLA-B27 TG rats.

CONCLUSIONS

Bacterial ileitis, increased zonulin expression and damaged intestinal mucosal barrier and GVB, characterises the gut of patients with AS and are associated with increased blood levels of zonulin, and bacterial products. Bacterial products and zonulin influence monocyte behaviour.

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.

Collaborative Interferon-γ and Interleukin-17 Signaling Protects the Oral Mucosa from Staphylococcus aureus

Infections with Staphylococcus aureus are a continuing and growing problem in community and hospital settings. Preclinical animal modeling of S. aureus relies on experimental infection, which carries some limitations. We describe here a novel, spontaneous model of oral staphylococcal infection in double knockout mice, deficient in the receptors for IL-17 (IL-17RA) and interferon (IFN)-γ (IFNγRI), beginning at 6 to 8 weeks of age. IFNγRI(-/-)IL17RA(-/-) (GRAKO) mice developed progressive oral abscesses. Cytometric methods revealed extensive neutrophilic infiltration of oral tissues in GRAKO mice; further investigation evidenced that IL-17 predominated neutrophil defects in these mice. To investigate the contribution of IFN-γ signaling to this native host defense to S. aureus, we observed perturbations of monocyte recruitment and macrophage differentiation in the oral tissues of GRAKO mice, and CXCL9/chemokine ligand receptor (CXCR)3-driven recruitment of T-cell oral tissues and draining lymph nodes. To address the former finding, we depleted macrophages and monocytes in vivo from IL17RA(-/-) mice using liposomes loaded with clodronate. This treatment elicited oral abscesses, recapitulating the phenotype of GRAKO mice. From these findings, we propose novel collaborative functions of IL-17 and IFN-γ, acting through neutrophils and macrophages, respectively, in native mucocutaneous host defenses to S. aureus.

Subclinical gut inflammation in ankylosing spondylitis

PURPOSE OF REVIEW

Subclinical gut inflammation has been described in a significant proportion of patients with ankylosing spondylitis (AS), up to 10% of them developing it during the time of clinically overt inflammatory bowel disease. Histologic, immunologic, and intestinal microbiota alterations characterize the AS gut.

RECENT FINDINGS

Microbial dysbiosis as well as alterations of innate immune responses have been demonstrated in the gut of AS. Furthermore, a growing body of evidence suggests that the gut of AS patients may be actively involved in the pathogenesis of AS through the production of proinflammatory cytokines, such as IL-23p19, and the differentiation of potentially pathogenic innate lymphoid cells producing IL-22 and IL-17. Finally, a strong correlation between the presence of subclinical gut inflammation and the degree of spine inflammation have been also proved in AS.

SUMMARY

Subclinical gut inflammation and innate immune responses in AS may be considered a possible consequence of microbial dysbiosis. Relationships between cause and effect remain, however, to be answered.

CD163+ M2c-like macrophages predominate in renal biopsies from patients with lupus nephritis

Background

The role of macrophages in the pathogenesis of lupus nephritis, in particular their differentiation to a certain subtype (e.g., M1- or M2-like) modulating the inflammatory reaction, is unknown. Here we investigated whether the differentiation in M1- or M2-like macrophages depends on the stage of lupus nephritis and whether this correlates with clinical parameters.

Method

Using immunohistochemical analysis we analyzed renal biopsies from 68 patients with lupus nephritis (ISN/RPS classes II–V) for infiltration with M1-like (iNOS+/CD68+), M2a-like (CD206+/CD68+), M2c-like macrophages (CD163+/CD68+), and FoxP3+ regulatory T-cells. In addition, clinical parameters at the time of renal biopsy, i.e., blood pressure, proteinuria and serum urea were correlated with the macrophage infiltration using the Spearman test.

Results

The mean number of CD68+ macrophages was related to the diagnosed ISN/RPS class, showing the highest macrophage infiltration in biopsies with diffuse class IV and the lowest number in ISN/RPS class V. In all ISN/RPS classes we detected more M2c-like CD163+/CD68+ than M2a-like CD206+/CD68+ cells, while M1-macrophages played only a minor role. Cluster analysis using macrophage subtype numbers in different renal compartments revealed three main clusters showing cluster 1 dominated by class V. Clusters 2 and 3 were dominated by lupus class IV indicating that this class can be further differentiated by its macrophage population. The number of tubulointerstitial FoxP3+ cells correlated with all investigated macrophage subtypes showing the strongest association to numbers of M2a-like macrophages. Kidney function, as assessed by serum creatinine and serum urea, correlated positively with the number of total CD68+, M2a-like and M2c-like macrophages in the tubulointerstitium. In addition, total CD68+ and M2c-like macrophage numbers highly correlated with Austin activity score. Interestingly, in hypertensive lupus patients only the number of M2a-like macrophages was significantly increased compared to biopsies from normotensive lupus patients.

Conclusion

M2-like macrophages are the dominant subpopulation in human lupus nephritis and particularly, M2a subpopulations were associated with disease progression, but their role in disease progression remains unclear.

Microbiome and probiotics: link to arthritis

PURPOSE OF REVIEW

The gut microbiome plays an integral role in the development and maintenance of the host immune system. Expanding knowledge about this microbial microenvironment has raised the possibility of new treatments based on this knowledge. In this review, we describe the recent evidence of the impact of the gut microbiome on arthritis and possible novel therapeutic approaches to alter the gut flora.

RECENT FINDINGS

Recent studies support the growing evidence of microbiome as a causative agent underlying certain rheumatic diseases like ankylosing spondylitis and rheumatoid arthritis. There is intriguing yet still inconclusive evidence to support the use of probiotics as a treatment for these diseases.

SUMMARY

There is recently a new level of understanding how the microbiome interacts with the immune system. Gene-environment interaction is another important element that sets the stage for initiation of autoimmune disease, which calls for further investigation. Probiotics could be an appealing therapeutic strategy, but further interventional studies exploring the dynamic interaction of microbiome and probiotics are still needed.

Update on ankylosing spondylitis: current concepts in pathogenesis

Ankylosing spondylitis is an insidiously progressive and debilitating form of arthritis involving the axial skeleton. The long delay in diagnosis and insufficient response to currently available therapeutics both advocate for a greater understanding of disease pathogenesis. Genome-wide association studies of this highly genetic disease have implicated specific immune pathways, including the interleukin (IL)-17/IL-23 pathway, control of nuclear factor kappa B (NF-κB) activation, amino acid trimming for major histocompatibility complex (MHC) antigen presentation, and other genes controlling CD8 and CD4 T cell subsets. The relevance of these pathways has borne out in animal and human subject studies, in particular, the response to novel therapeutic agents. Genetics and the findings of autoantibodies in ankylosing spondylitis revisit the question of autoimmune vs. autoinflammatory etiology. As environmental partners to genetics, recent attention has focused on the roles of microbiota and biomechanical stress in initiating and perpetuating inflammation. Herein, we review these current developments in the investigation of ankylosing spondylitis pathogenesis.

Raised incidence of ankylosing spondylitis among Inuit populations could be due to high HLA-B27 association and starch consumption

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis mainly affecting the spinal joints. It would appear that the most likely causative agent in the development of AS is an environmental factor in the genetically susceptible, HLA-B27 positive, individuals. Extensive data from several countries support the notion that Klebsiella pneumonia bacteria are the most likely culprit in the causation of AS. These microbes possess antigens which resemble HLA-B27 and spinal collagens. Increased intake of high-starch diet is directly proportional to the gut-associated bacterial load, especially in the large intestine, and among these microbial agents, Klebsiella is considered as one of the main constituting components. Therefore, a low-starch diet intake alongside the currently used medical therapeutic modalities could be beneficial in the management of patients with early AS. It is suggested that a change in the dietary habits from high protein, low-starch marine components to the Westernized high-starch diet among the Inuit peoples of Alaska and Canada could be considered as one of the main contributing factors in the increased prevalence of AS during the last few decades within this genetically unmixed native population.

Islet amyloid with macrophage migration correlates with augmented β-cell deficits in type 2 diabetic patients

AIMS

Islet amyloid is a hallmark in type 2 diabetic subjects, but its implication in clinical features and development of islet pathology is still unclear.

METHODS

From 118 autopsy cases with type 2 diabetes, 26 cases with islet amyloid deposition (DA+) were selected. Twenty diabetic subjects without obvious amyloid deposition (DA-) matched for the age and diabetes duration and 20 non-diabetic subjects (ND) served for comparison. We examined the severity of amyloid deposition and its relationships with population of endocrine cells, expression of cell damage markers or macrophage infiltration. Correlation of clinical profile with islet pathology was also sought on the subset of the investigated patients.

RESULTS

β-Cell volume density was nearly 40% less in DA+ and 20% less in DA- when compared to ND. Severity of amyloid deposition correlated with reduced volume densities of β-cell and α-cell, and increased body mass index (BMI), but not with duration of diabetes, age or HbA1c. Amyloid-rich islets contained an increased number of macrophages mixed with β-cells with oxidative stress-related DNA damage, characterized by γH2AX expression, and suppressed (pro)insulin mRNA expression.

CONCLUSIONS

In Japanese type 2 diabetic patients, islet amyloid was more common with severe β-cell loss and high BMI, associated with macrophage infiltration.

Anti-inflammatory activity of extracts of Bushen-Qiangdu-Zhilv decoction, a Chinese medicinal formula, in M1-polarized RAW264.7

Background

Bushen-Qiangdu-Zhilv Decoction (BQZ) is one of famous traditional Chinese medical formula for treating ankylosing spondylitis (AS). However, the mechanisms underlying effects of BQZ remains unknown. Pro-inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1, play an important role in AS. We therefore evaluated if BQZ could affect the expression of these cytokines.

Methods

Crude extracts were prepared and fractioned with petroleum ether (PE), ethyl acetate (EA), n-butanol (BU) and finally water (ACE). The stability of the extracts was confirmed by high-pressure liquid chromatography (HPLC) analysis. M1-polarized RAW264.7 was induced and subsequently treated with BQZ extracts. Quantitative real-time PCR experiments were performed to measure mRNA expression of TNF-α and IL-1.

Results

It was found that TNF-α could be significantly suppressed by ACE extracts, whereas IL-1 was dramatically inhibited by BU extracts, which was further confirmed by dose-dependent experiments. Importantly, MTS assays showed that both ACE and BU extracts had a low cytotoxicity.

Conclusion

Altogether, our study indicates that BQZ decoction exerts anti-AS effects via its anti-inflammatory activity and may have a low side-effect. Further analysis of the extracts of BQZ decoction could lead to a discovery of some novel drugs adding to therapeutic strategy for AS patients.