Colon mucosa of patients both with spondyloarthritis and Crohn's disease is enriched with macrophages expressing the scavenger receptor CD163

Urinary soluble CD163 is a putative non-invasive biomarker for primary sclerosing cholangitis

Soluble CD163 (sCD163) is a selective marker of macrophages whose circulating levels have been found to be induced in patients with active inflammatory bowel disease (IBD). Urinary proteins are emerging as non-invasive diagnostic biomarkers, and here, sCD163 levels were measured in the urine of 18 controls and 63 patients with IBD by enzyme-linked immunosorbent assay. Urinary sCD163 levels did, however, not differentiate IBD patients from controls. Analysis of sCD163 in the serum of 51 of these patients did not show higher levels in IBD. Primary sclerosing cholangitis (PSC) is often associated with IBD, and sCD163 was higher in the urine of the 21 patients and in the serum of the 13 patients with PSC compared to patients with IBD. Of clinical relevance, urinary sCD163 levels were higher in PSC patients compared to those with other chronic liver diseases (n = 16), while serum sCD163 levels were comparable between the two groups. Serum sCD163 of IBD and PSC patients positively correlated with serum C-reactive protein. Serum creatinine and glomerular filtration rate, surrogate markers for renal function, did not significantly correlate with urinary or serum sCD163 levels in IBD or PSC patients. Moreover, urinary sCD163 was not related to fecal calprotectin levels whereas serum sCD163 of IBD patients showed a positive trend. PSC associated with IBD and PSC without underlying IBD had similar levels of urinary sCD163 while serum sCD163 tended to be higher in the latter group. In PSC patients, urinary sCD163 did not correlate with serum aminotransferase levels, gamma glutamyl transferase, alkaline phosphatase, bilirubin or the Model for End Stage Liver Disease score. Ursodeoxycholic acid was prescribed to our PSC patients and fecal levels of ursodeoxycholic acid and its conjugated forms were increased in PSC compared to IBD patients. Otherwise, fecal bile acid levels of IBD and PSC patients were almost identical, and were not correlated with urinary and serum sCD163 in PSC. In summary, our study identified urinary sCD163 as a potential biomarker for PSC.

Immune Cell-Mediated Autoimmune Responses in Severe Asthma

Severe asthma (SA) has heterogeneous inflammatory phenotypes characterized by persistent airway inflammation (eosinophilic and/or neutrophilic inflammation) and remodeling. Various immune cells (eosinophils, neutrophils, and macrophages) become more activated and release inflammatory mediators and extracellular traps, damaging the protective barrier of airway epithelial cells and further activating other immune and structural cells. These cells play a role in autoimmune responses in asthmatic airways, where the adaptive immune system generates autoantibodies, inducing immunoglobulin G-dependent airway inflammation. Recent studies have suggested that adult asthmatics had high titers of autoantibodies associated with asthma severity, although pathogenic factors or diagnostic criteria are not well-defined. This challenge is further compounded by asthmatics with the autoimmune responses showing therapy insensitivity or failure to current pharmacological and biological treatment. This review updates emerging mechanisms of autoimmune responses in asthmatic airways and provides insights into their roles, proposing potential biomarkers and therapeutic targets for SA.

CD83 Regulates the Immune Responses in Inflammatory Disorders

Activating the immune system plays an important role in maintaining physiological homeostasis and defending the body against harmful infections. However, abnormalities in the immune response can lead to various immunopathological responses and severe inflammation. The activation of dendritic cells (DCs) can influence immunological responses by promoting the differentiation of T cells into various functional subtypes crucial for the eradication of pathogens. CD83 is a molecule known to be expressed on mature DCs, activated B cells, and T cells. Two isotypes of CD83, a membrane-bound form and a soluble form, are subjects of extensive scientific research. It has been suggested that CD83 is not only a ubiquitous co-stimulatory molecule but also a crucial player in monitoring and resolving inflammatory reactions. Although CD83 has been involved in immunological responses, its functions in autoimmune diseases and effects on pathogen immune evasion remain unclear. Herein, we outline current immunological findings and the proposed function of CD83 in inflammatory disorders.

Netrin-1: A Modulator of Macrophage Driven Acute and Chronic Inflammation

Netrins belong to the family of laminin-like secreted proteins, which guide axonal migration and neuronal growth in the developing central nervous system. Over the last 20 years, it has been established that netrin-1 acts as a chemoattractive or chemorepulsive cue in diverse biological processes far beyond neuronal development. Netrin-1 has been shown to play a central role in cell adhesion, cell migration, proliferation, and cell survival in neuronal and non-neuronal tissue. In this context, netrin-1 was found to orchestrate organogenesis, angiogenesis, tumorigenesis, and inflammation. In inflammation, as in neuronal development, netrin-1 plays a dichotomous role directing the migration of leukocytes, especially monocytes in the inflamed tissue. Monocyte-derived macrophages have long been known for a similar dual role in inflammation. In response to pathogen-induced acute injury, monocytes are rapidly recruited to damaged tissue as the first line of immune defense to phagocyte pathogens, present antigens to initiate the adaptive immune response, and promote wound healing in the resolution phase. On the other hand, dysregulated macrophages with impaired phagocytosis and egress capacity accumulate in chronic inflammation sites and foster the maintenance-and even the progression-of chronic inflammation. In this review article, we will highlight the dichotomous roles of netrin-1 and its impact on acute and chronic inflammation.

The arthritis connection to inflammatory bowel disease (IBD): why has it taken so long to understand it?

Inflammatory bowel disease (IBD) associated arthritis is a subgroup of spondyloarthritis (SpA) that has suffered from lack of recognition in rheumatology clinical and research circles for over 100 years. Although clinically distinguishable from rheumatoid arthritis and ankylosing spondylitis, it took advances in detection systems in the middle of the last century (rheumatoid factor, HLA-B27) to convincingly make the final separations. We now know that significant numbers of patients with SpA have associated clinical IBD and almost half of them show subclinical gut inflammation, yet the connection between the gut and the musculoskeletal system has remained a vexing problem. Two publications from Nathan Zvaifler (one in 1960, the other in 1975) presciently described the relationship between the gut and the spine/peripheral joints heralding much of the work present today in laboratories around the world trying to examine basic mechanisms for the connections (there are likely to be many) between the gut, the environment (presumably our intestinal flora) and the downstream effect on the musculoskeletal system. The role of dysregulated microbiome along with microbiome-driven T helper 17 cell expansion and immune cell migration to the joints has been recognised, all of which occur in the appropriate context of genetic background inside and outside of the human leucocyte antigen system. Moreover, different adhesion molecules that mediate immune cells homing to the gut and joints have been noted. In this review, we studied the origins and evolution of IBD-arthritis, proposed pathogenic mechanisms and the current gaps that need to be filled for a complete understanding of IBD-arthritis.

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.

Gut epithelial impairment, microbial translocation and immune system activation in inflammatory bowel disease-associated spondyloarthritis

OBJECTIVES

Gut microbiota has been widely reported to be involved in systemic inflammation through microbial translocation and T cell activation in several diseases. In this work we aimed to investigate bacterial infiltration and epithelial impairment in the gut of patients with IBD-associated SpA (SpA-IBD), as well as the relationship of microbial translocation with immune system activation and their putative role in the pathogenesis of joint inflammation in IBD patients.

METHODS

Tight-junction proteins (TJPs) occludin and claudin-1/-4 and bacteria were assessed by real-time PCR analysis and immunohistochemical staining of the ileum. Intestinal fatty acid binding protein (I-FABP), lipopolysaccharides (LPS), soluble CD14 (sCD14), sclerostin and anti-sclerostin antibodies (anti-sclerostin-IgG) were assayed with ELISAs and peripheral mononuclear blood cells with flow cytometry. LPS and sCD14 were used in vitro to stimulate a human osteoblast cell line.

RESULTS

Compared with IBD, ileal samples from SpA-IBD patients showed bacterial infiltration, epithelial damage and downregulation of TJPs. In sera, they showed higher serum levels of I-FABP, LPS, sCD14 (the latter correlating with sclerostin and anti-sclerostin-IgG) and higher CD80+/CD163+ and lower CD14+ mononuclear cells. In vitro experiments demonstrated that only the LPS and sCD14 synergic action downregulates sclerostin expression in osteoblast cells.

CONCLUSION

SpA-IBD patients are characterized by gut epithelium impairment with consequent translocation of microbial products into the bloodstream, immune system activation and an increase of specific soluble biomarkers. These findings suggest that gut dysbiosis could be involved in the pathogenesis of SpA-IBD and it could hopefully prompt the use of these biomarkers in the follow-up and management of IBD patients.

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.

Targeting of CD163+ Macrophages in Inflammatory and Malignant Diseases

The macrophage is a key cell in the pro- and anti-inflammatory response including that of the inflammatory microenvironment of malignant tumors. Much current drug development in chronic inflammatory diseases and cancer therefore focuses on the macrophage as a target for immunotherapy. However, this strategy is complicated by the pleiotropic phenotype of the macrophage that is highly responsive to its microenvironment. The plasticity leads to numerous types of macrophages with rather different and, to some extent, opposing functionalities, as evident by the existence of macrophages with either stimulating or down-regulating effect on inflammation and tumor growth. The phenotypes are characterized by different surface markers and the present review describes recent progress in drug-targeting of the surface marker CD163 expressed in a subpopulation of macrophages. CD163 is an abundant endocytic receptor for multiple ligands, quantitatively important being the haptoglobin-hemoglobin complex. The microenvironment of inflammation and tumorigenesis is particular rich in CD163⁺ macrophages. The use of antibodies for directing anti-inflammatory (e.g., glucocorticoids) or tumoricidal (e.g., doxorubicin) drugs to CD163⁺ macrophages in animal models of inflammation and cancer has demonstrated a high efficacy of the conjugate drugs. This macrophage-targeting approach has a low toxicity profile that may highly improve the therapeutic window of many current drugs and drug candidates.

Drug delivery to macrophages: A review of targeting drugs and drug carriers to macrophages for inflammatory diseases

Macrophages play a key role in defending against foreign pathogens, healing wounds, and regulating tissue homeostasis. Driving this versatility is their phenotypic plasticity, which enables macrophages to respond to subtle cues in tightly coordinated ways. However, when this coordination is disrupted, macrophages can aid the progression of numerous diseases, including cancer, cardiovascular disease, and autoimmune disease. The central link between these disorders is aberrant macrophage polarization, which misguides their functional programs, secretory products, and regulation of the surrounding tissue microenvironment. As a result of their important and deterministic roles in both health and disease, macrophages have gained considerable attention as targets for drug delivery. Here, we discuss the role of macrophages in the initiation and progression of various inflammatory diseases, summarize the leading drugs used to regulate macrophages, and review drug delivery systems designed to target macrophages. We emphasize strategies that are approved for clinical use or are poised for clinical investigation. Finally, we provide a prospectus of the future of macrophage-targeted drug delivery systems.

The Role of Monocytes and Macrophages in Autoimmune Diseases: A Comprehensive Review

Monocytes (Mo) and macrophages (Mϕ) are key components of the innate immune system and are involved in regulation of the initiation, development, and resolution of many inflammatory disorders. In addition, these cells also play important immunoregulatory and tissue-repairing roles to decrease immune reactions and promote tissue regeneration. Several lines of evidence have suggested a causal link between the presence or activation of these cells and the development of autoimmune diseases. In addition, Mo or Mϕ infiltration in diseased tissues is a hallmark of several autoimmune diseases. However, the detailed contributions of these cells, whether they actually initiate disease or perpetuate disease progression, and whether their phenotype and functional alteration are merely epiphenomena are still unclear in many autoimmune diseases. Additionally, little is known about their heterogeneous populations in different autoimmune diseases. Elucidating the relevance of Mo and Mϕ in autoimmune diseases and the associated mechanisms could lead to the identification of more effective therapeutic strategies in the future.

Inflammatory bowel diseases and spondyloarthropathies: From pathogenesis to treatment

Spondyloarthropathies (SpA) include many different forms of inflammatory arthritis and can affect the spine (axial SpA) and/or peripheral joints (peripheral SpA) with Ankylosing spondylitis (AS) being the prototype of the former. Extra-articular manifestations, like uveitis, psoriasis and inflammatory bowel disease (IBD) are frequently observed in the setting of SpA and are, in fact, part of the SpA classification criteria. Bowel involvement seems to be the most common of these manifestations. Clinically evident IBD is observed in 6%-14% of AS patients, which is significantly more frequent compared to the general population. Besides, it seems that silent microscopic gut inflammation, is evident in around 60% in AS patients. Interestingly, occurrence of IBD has been associated with AS disease activity. For peripheral SpA, two different forms have been proposed with diverse characteristics. Of note, SpA (axial or peripheral) is more commonly observed in Crohn's disease than in ulcerative colitis. The common pathogenetic mechanisms that explain the link between IBD and SpA are still ill-defined. The role of dysregulated microbiome along with migration of T lymphocytes and other cells from gut to the joint ("gut-joint" axis) has been recognized, in the context of a genetic background including associations with alleles inside or outside the human leukocyte antigen system. Various therapeutic modalities are available with monoclonal antibodies against tumour necrosis factor, interleukin-23 and interleukin-17, being the most effective. Both gastroenterologists and rheumatologists should be alert to identify the co-existence of these conditions and ideally follow-up these patients in combined clinics.

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.

Lack of high BMI-related features in adipocytes and inflammatory cells in the infrapatellar fat pad (IFP)

Background

Obesity is associated with the development and progression of osteoarthritis (OA). Although the infrapatellar fat pad (IFP) could be involved in this association, due to its intracapsular localization in the knee joint, there is currently little known about the effect of obesity on the IFP. Therefore, we investigated cellular and molecular body mass index (BMI)-related features in the IFP of OA patients.

Methods

Patients with knee OA (N = 155, 68% women, mean age 65 years, mean (SD) BMI 29.9 kg/m2 (5.7)) were recruited: IFP volume was determined by magnetic resonance imaging in 79 patients with knee OA, while IFPs and subcutaneous adipose tissue (SCAT) were obtained from 106 patients undergoing arthroplasty. Crown-like structures (CLS) were determined using immunohistochemical analysis. Adipocyte size was determined by light microscopy and histological analysis. Stromal vascular fraction (SVF) cells were characterized by flow cytometry.

Results

IFP volume (mean (SD) 23.6 (5.4) mm³) was associated with height, but not with BMI or other obesity-related features. Likewise, volume and size of IFP adipocytes (mean 271 pl, mean 1933 μm) was not correlated with BMI. Few CLS were observed in the IFP, with no differences between overweight/obese and lean individuals. Moreover, high BMI was not associated with higher SVF immune cell numbers in the IFP, nor with changes in their phenotype. No BMI-associated molecular differences were observed, besides an increase in TNFα expression with high BMI. Macrophages in the IFP were mostly pro-inflammatory, producing IL-6 and TNFα, but little IL-10. Interestingly, however, CD206 and CD163 were associated with an anti-inflammatory phenotype, were the most abundantly expressed surface markers on macrophages (81% and 41%, respectively) and CD163⁺ macrophages had a more activated and pro-inflammatory phenotype than their CD163^- counterparts.

Conclusions

BMI-related features usually observed in SCAT and visceral adipose tissue could not be detected in the IFP of OA patients, a fat depot implicated in OA pathogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1395-9) contains supplementary material, which is available to authorized users.

Macrophages Versus Escherichia coli: A Decisive Fight in Crohn's Disease

The pathophysiology of Crohn's disease (CD), a chronic inflammatory bowel disease, remains imperfectly elucidated. Consequently, the therapeutic armamentarium remains limited and has not changed the natural history of CD hitherto. Accordingly, physicians need to identify new therapeutic targets to be able to alter the intestinal damage. The most recent hypothesis considered CD as resulting from an abnormal interaction between microbiota and host immune system influenced by genetics and environmental factors. Several experimental and genetic evidence point out intestinal macrophages in CD etiology. An increase of macrophages number and the presence of granulomas are especially observed in the intestinal mucosa of patients with CD. These macrophages could be defective and particularly in responses to infectious agents like CD-associated Escherichia coli. This review focuses on, what is currently known regarding the role of macrophages, macrophages/E. coli interaction, and the impact of CD therapies on macrophages in CD. We also speculate that macrophages modulation could lead to important translational implications in CD with the end goal of promoting gut health.

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.

Diversity of Intestinal Macrophages in Inflammatory Bowel Diseases

Macrophages as innate immune cells and fast responders to antigens play a central role in protecting the body from the luminal content at a huge interface. Chronic inflammation in inflammatory bowel diseases massively alters the number and the subset diversity of intestinal macrophages. We here address the diversity within the human intestinal macrophage compartment at the level of similarities and differences between homeostasis and chronic intestinal inflammation as well as between UC and CD, including the potential role of macrophage subsets for intestinal fibrosis. Hallmark of macrophages is their enormous plasticity, i.e., their capacity to integrate signals from their environment thereby changing their phenotype and functions. Tissue-resident macrophages located directly beneath the surface epithelium in gut homeostasis are mostly tolerogenic. The total number of macrophages increases with luminal contents entering the mucosa through a broken intestinal barrier in ulcerative colitis (UC) as well as in Crohn's disease (CD). Although not fully understood, the resulting mixtures of tissue-resident and tissue-infiltrating macrophages in both entities are diverse with respect to their phenotypes and their distribution. Macrophages in UC mainly act within the intestinal mucosa. In CD, macrophages can also be found in the muscularis and the mesenteric fat tissue compartment. Taken together, the present knowledge on human intestinal macrophages so far provides a good starting point to dig deeper into the similarities and differences of functional subsets and to finally use their phenotypical diversity as markers for complex local milieus in health and disease.

Prediction of Response to Therapy for Autoimmune/Inflammatory Diseases Using an Activated Macrophage-Targeted Radioimaging Agent

The ability to select patients who will respond to therapy is especially acute for autoimmune/inflammatory diseases, where the costs of therapies can be high and the progressive damage associated with ineffective treatments can be irreversible. In this article we describe a clinical test that will rapidly predict the response of patients with an autoimmune/inflammatory disease to many commonly employed therapies. This test involves quantitative assessment of uptake of a folate receptor-targeted radioimaging agent ((99m)Tc-EC20) by a subset of inflammatory macrophages that accumulate at sites of inflammation. Murine models of four representative inflammatory diseases (rheumatoid arthritis, inflammatory bowel disease, pulmonary fibrosis, and atherosclerosis) show markedly decreased uptake of (99m)Tc-EC20 in inflamed lesions upon initiation of successful therapies, but no decrease in uptake upon administration of ineffective therapies, in both cases long before changes in clinical symptoms can be detected. This predictive capability should reduce costs and minimize morbidities associated with failed autoimmune/inflammatory disease therapies.

Occult spondyloarthritis in inflammatory bowel disease

Spondyloarthritis (SpA) is a frequent extra-intestinal manifestation in patients with inflammatory bowel disease (IBD), although its real diffusion is commonly considered underestimated. Abnormalities in the microbioma and genetic predisposition have been implicated in the link between bowel and joint inflammation. Otherwise, up to date, pathogenetic mechanisms are still largely unknown and the exact influence of the bowel activity on rheumatic manifestations is not clearly explained. Due to evidence-based results of clinical studies, the interest on clinically asymptomatic SpA in IBD patients increased in the last few years. Actually, occult enthesitis and sacroiliitis are discovered in high percentages of IBD patients by different imaging techniques, mainly enthesis ultrasound (US) and sacroiliac joint X-ray examinations. Several diagnostic approaches and biomarkers have been proposed in an attempt to correctly classify and diagnose clinically occult joint manifestations and to define clusters of risk for patient screening, although definitive results are still lacking. The correct recognition of occult SpA in IBD requires an integrated multidisciplinary approach in order to identify common diagnostic and therapeutic strategies. The use of inexpensive and rapid imaging techniques, such as US and X-ray, should be routinely included in daily clinical practice and trials to correctly evaluate occult SpA, thus preventing future disability and worsening of quality of life in IBD patients.

Immunopathology of synovitis: from histology to molecular pathways

Increased knowledge about pathological processes active in inflammatory joint diseases is needed to initiate personalized medicine based on targeted treatments in the future. The molecular and cellular pathways that are active during joint inflammation may differ between the various inflammatory joint diseases, between different patient subgroups within one disease, or even between different stages of the disease in a single patient. In this review, we evaluate synovial inflammation in terms of descriptive histopathology through to more functional studies on human synovial tissue inflammation in RA and SpA, in phenotypic subgroups of RA and SpA patients, and during the disease course of both diseases.

Drug Trafficking into Macrophages via the Endocytotic Receptor CD163

In inflammatory diseases, macrophages are a main producer of a range of cytokines regulating the inflammatory state. This also includes inflammation induced by tumor growth, which recruits so-called tumor-associated macrophages supporting tumor growth. Macrophages are therefore relevant targets for cytotoxic or phenotype-modulating drugs in the treatment of inflammatory and cancerous diseases. Such targeting of macrophages has been tried using the natural propensity of macrophages to non-specifically phagocytose circulating foreign particulate material. In addition, the specific targeting of macrophage-expressed receptors has been used in order to obtain a selective uptake in macrophages and reduce adverse effects of off-target delivery of drugs. CD163 is a highly expressed macrophage-specific endocytic receptor that has been studied for intracellular delivery of small molecule drugs to macrophages using targeted liposomes or antibody drug conjugates. This review will focus on the biology of CD163 and its potential role as a target for selective macrophage targeting compared with other macrophage targeting approaches.

Soluble CD163, a specific macrophage activation marker, is decreased by anti-TNF-α antibody treatment in active inflammatory bowel disease

Activated macrophages shed the haemoglobin-haptoglobin scavenger receptor CD163 into the circulation as soluble(s)-CD163. We measured sCD163 as an in vivo macrophage activation marker in patients with Crohn's disease (CD) or ulcerative colitis (UC) receiving antitumour necrosis factor (TNF)-α antibody or prednisolone treatment. We also investigated the CD163 expression on circulating monocytes. 58 patients with CD, 40 patients with UC and 90 healthy controls (HC) were included. All patients had active disease at inclusion and were followed for 6 weeks of anti-TNF-α antibody or prednisolone treatment. We measured plasma sCD163 levels at baseline, 1 day, 1 week and 6 weeks after initiating treatment. CD163 expression on circulating CD14(+) monocytes was measured in 21 patients with CD receiving anti-TNF-α antibody treatment. Baseline sCD163 levels were elevated in patients with CD [1.99 (1.80-2.18) mg/l] and in patients with UC [2.07 (1.82-2.32) mg/l] compared with HC [1.51 (1.38-1.63) mg/l] (P < 0.001). Anti-TNF-α antibody treatment induced a rapid decrease in sCD163 levels in patients with CD and in patients with UC 1 day after treatment initiation (P < 0.05). One week of prednisolone treatment did not induce a reduction in sCD163 levels. Anti-TNF-α treatment normalized sCD163 levels in patients with UC, whereas patients with CD exhibited sustained increased sCD163 levels. In patients with CD, CD163 expression on CD14(+) monocytes was increased compared with HC. This study highlights that active CD and UC are associated with increased macrophage activation, as indicated by elevated sCD163 levels and monocytic CD163 expression. Anti-TNF-α antibody treatment induced a rapid decrease in sCD163 levels, suggesting a specific effect on macrophage activation in inflammatory bowel diseases.

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

OBJECTIVE

Long-term evolution of subclinical gut inflammation to overt Crohn's disease (CD) has been described in AS patients. The aim of this study was to evaluate macrophage polarization occurring in the inflamed gut of patients with AS.

METHODS

Twenty-seven HLA-B27(+) AS patients, 20 CD patients and 17 normal controls were consecutively enrolled. Classic M1 (iNOS(+)IL-10(-)), resolution phase (iNOS(+)IL-10(+)), M2 and CD14(+) macrophages were characterized by immunohistochemistry and flow cytometry. Quantitative gene expression analysis of IFN-γ, IL-4, IL-5, IL-33 and STAT6 was performed by real time PCR.

RESULTS

Classic M1 macrophages were expanded in CD and AS, where resolution phase macrophages predominate. A large increase in CD163(+) (M2) macrophages was observed in AS strictly correlated with the expression of IL-33, a Th2 cytokine involved in M2 polarization. Unlike in CD, CD14(+) macrophages were virtually absent in the gut of AS patients and controls.

CONCLUSION

The absence of CD14(+) macrophages together with the expansion of resolution phase and M2 macrophages is the immunological signature of subclinical ileal inflammation in AS.

Caspase-1 level in synovial fluid is high in patients with spondyloarthropathy but not in patients with gout

Activation of caspase-1 by NALP3 inflammasomes has been shown to be important in initiating acute gouty arthritis. The objectives of this study were to measure the levels of caspase-1 in synovial fluid in gout and various arthritides, and to elucidate the clinical significance of caspase-1 levels in synovial fluid. Caspase-1, IL-1β, IL-18, and uric acid were measured in synovial fluid from 112 patients with gout and other arthritides, such as rheumatoid arthritis, osteoarthritis, and spondyloarthropathy. Caspase-1 in synovial fluid from patients with crystal-induced arthritis, inflammatory arthritis, osteoarthritis, and spondyloarthropathy was 35.9 ± 86.7, 49.7 ± 107.7, 2.1 ± 7.0, and 152.6 ± 155.7 pg/mL, respectively. The mean level and the frequency of high levels (≥125 pg/mL) of caspase-1 in spondyloarthropathy were significantly higher than those in the other arthritides including gout. Caspase-1 was detectible in the synovial fluid of patients with the various arthritides. Contrary to our hypothesis, the caspase-1 level in the synovial fluid of patients with gout was not higher than in that of other arthritides. High levels of caspase-1 may be helpful in differentiating spondyloarthropathy from other arthritides.

Lesional accumulation of CD163-expressing cells in the gut of patients with inflammatory bowel disease

Monocytes/macrophages displaying different markers of activation/differentiation infiltrate the inflamed gut of patients with inflammatory bowel diseases (IBD), but the role that each monocyte/macrophage subpopulation plays in the pathogenesis of IBD is not fully understood. The hemoglobin scavenger receptor CD163, a specific marker of monocytes/macrophages, has been associated with either anti-inflammatory or inflammatory functions of macrophages in several pathologies. In this study we examined the tissue distribution and function of CD163-expressing monocytes/macrophages in IBD. CD163 RNA and protein expression was more pronounced in IBD in comparison to normal controls, with no significant difference between Crohn's disease and Ulcerative colitis. In IBD, over-expression of CD163 was restricted to areas with active inflammation and not influenced by current therapy. Immunohistochemical analysis confirmed the accumulation of CD163-expressing cells in IBD, mostly around and inside blood vessels, thus suggesting that these cells are partly recruited from the systemic circulation. Indeed, FACS analysis of circulating mononuclear cells showed that the fractions of CD163-positive monocytes were increased in IBD patients as compared to controls. Functionally, interleukin-6 up-regulated CD163 expression in lamina propria mononuclear cells and mucosal explants of normal subjects. In IBD blood and mucosal cell cultures, cross-linking of CD163 with a specific monoclonal anti-CD163 antibody enhanced tumor necrosis factor-α synthesis. These findings indicate that IBD mucosa is abundantly infiltrated with CD163-positive cells, which could contribute to amplify the inflammatory cytokine response.

Pathophysiology and role of the gastrointestinal system in spondyloarthritides

Inflammatory bowel disease (IBD) is a well-known extra-articular manifestation in spondyloarthritis (SpA); about 6.5% of patients with ankylosing spondylitis develop IBD during the course of the disease. The pathogenesis of both SpA and IBD is considered to be the result of a complex interplay between the host (genetic predisposition), the immune system and environmental factors, notably microorganisms, leading to a disturbed immune system and chronic inflammation. Over the past decade, the role of tumor necrosis factor inhibition (infliximab, etanercept, adalimumab, golimumab) in improving signs and symptoms and overall quality of life has been well documented in various forms of SpA. Future research will clarify the role of other potential targets.

Pathogenesis of spondyloarthritis: autoimmune or autoinflammatory?

PURPOSE OF REVIEW

Spondyloarthritis (SpA) is a chronic immune-mediated inflammatory disease of unknown origin. Here we aim to review whether SpA is driven by T-cell and/or B-cell autoreactivity or by abnormal innate immune responses.

RECENT FINDINGS

SpA does not share genetic risk factors, female predominance, presence of disease-specific autoantibodies and response to T-cell or B-cell-targeted therapies with prototypical autoimmune diseases like rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Growing evidence indicates that increased responsiveness of innate immune cells such as macrophages, mast cells and neutrophils drives inflammation in SpA. The altered innate immune response may be related to nonantigen-presenting functions of HLA-B27, including the induction of an unfolded protein response, and can be triggered by bacterial and mechanical stress. Innate immune cells appear to be the main producers of both pro-inflammatory (tumor necrosis factor, IL-1, IL-23, IL-17) and anti-inflammatory (IL-10) cytokines in SpA.

SUMMARY

The predominance of myeloid above lymphoid alterations suggests an autoinflammatory rather than autoimmune origin of inflammation in SpA. Therefore, targeting innate cells or their inflammatory mediators may be more effective than T-cell or B-cell-directed therapies.

Synovial Tissue Response to Treatment with TNF Blockers in Peripheral Spondyloarthritis

This review describes the synovial response to treatment in peripheral spondyloarthritis (SpA). A series of recent studies demonstrates that the synovial histopathology is largely homogenous between different SpA subtypes and can be strongly modulated by effective treatment such as tumor necrosis factor (TNF) blockade. This includes a dramatic reduction of the infiltration with inflammatory cells (with the intriguing exception of B lymphocytes and plasma cells), a modulation of structural features such as vascularity, intimal lining layer hyperplasia, and ectopic lymphoid neogenesis, and a down-regulation of a variety of mediators involved in tissue damage. The analysis of tissue response to targeted therapies appears to be a novel and elegant approach to study the immunopathology of human peripheral SpA in vivo. Moreover, detailed cellular and molecular analysis of synovial features allows to identify synovial biomarkers of clinical response to therapeutic interventions which can be used in future early phase clinical trials in SpA.

Inflammatory bowel disease associated arthropathy

Arthritis is the most common extraintestinal manifestation of inflammatory bowel disease (IBD) and can have a significant impact on morbidity and quality of life. IBD-associated arthropathy is considered a subtype of seronegative spondyloarthropathy, with axial, peripheral, or a combination of both joint manifestations. Peripheral arthritis is generally non-erosive and the oligoarticular variant particularly may correlate with intestinal disease activity. Axial arthritis may include inflammatory back pain, sacroiliitis, or ankylosing spondylitis, and is less likely to correlate with gastrointestinal symptoms. While there have been advances in identifying predisposing genetic factors and in elucidating pathophysiology of inflammatory bowel disease, the mechanisms surrounding the development of arthritis in IBD remain unclear. Treatment of inflammatory bowel disease is not always sufficient for control of arthritis. While treatment with biologic agents is promising, there remains a great need for larger, randomized studies to address optimal therapy of IBD associated arthropathy.

Comprehensive study of cardiovascular morbidity in hospitalized inflammatory bowel disease patients

BACKGROUND

The full extent of cardiovascular morbidity in inflammatory bowel disease is not well understood.

OBJECTIVE

To comprehensively study the association of different cardiovascular diseases in hospitalized patients with inflammatory bowel disease (IBD) using a large database.

METHODS

We used the Nationwide Inpatient Sample (NIS) database to perform a cross-sectional study. The study group was defined as all hospitalized patients between ages 18-60 years included in the NIS 2006 database with a discharge diagnosis of IBD, as per the International Classification of Diseases - Clinical Modification, 9th revision (ICD-9-CM) codes. Individuals in the same age group whose hospital discharge records did not note IBD were identified as the control group. Cardiovascular diseases, identified by the ICD-9-CM codes, were studied comprehensively for their association with IBD using multivariate logistic regression analysis. Odds ratios were calculated adjusting for relevant patient comorbidities.

RESULTS

IBD was found to be strongly associated with mesenteric ischemia (adjusted odds ratio (aOR), 3.4; 95% confidence interval (CI), 2.9-4.0) and venous thrombotic diseases (aOR, 1.38; 95% CI, 1.25-1.53). Age and gender stratified analysis revealed that IBD is positively associated with dysrhythmias in females aged 18-39 years (aOR, 2.05; 95% CI, 1.72-2.44). We did not find an increased risk of other cardiovascular diseases in IBD patients.

CONCLUSIONS

Our study substantiates the previously reported associations of mesenteric ischemia and venous thrombotic disorders with IBD. Our study also suggests that young females with IBD might have an increased risk for dysrhythmias.

Bacterial agents in spondyloarthritis: a destiny from diversity?

The spondyloarthritides (SpAs) are a group of diseases that share clinical, radiographic and laboratory features; these arthritides also display a tendency for family aggregation. Given the intimate relationship that these types of arthritis share, it suggests that the SpAs might share a common aetiology. Of all the SpAs, the role of bacteria is most clearly defined in reactive arthritis. Tremendous recent insights into the pathophysiology of reactive arthritis have been made, demonstrating that the causative bacteria play a much more complex role than previously thought. The bacteria that are proven to cause reactive arthritis, one of the five types of SpA, will be reviewed and their role in the pathophysiology of reactive arthritis will be examined. The speculative data suggesting links between various other bacteria and the other types of SpAs will be critically analysed. Although these data are not definitive, when viewed using the paradigm that the SpAs might actually represent a common end point from several diverse starting points, they are provocative, suggesting that bacteria might, indeed, be aetiological for the entire group of SpAs.

Interactions between gut inflammation and arthritis/spondylitis

PURPOSE OF REVIEW

The spectrum of spondyloarthritis is characterized by the intriguing co-occurrence of gut and joint inflammation, although no obvious anatomical link exists.

RECENT FINDINGS

Data from animal models identify stromal cells as important players in pathogenesis, although signalling through TNFRI appeared to be sufficient for development of combined gut and joint inflammation. Interleukin-23 receptor was identified as a susceptibility locus for ankylosing spondylitis.

SUMMARY

Human genome studies combined with animal model research provide us with new evidence in the fascinating field of the gut-joint axis. However, how these newly identified genetic associations can influence the immunological environment remains to be elucidated.

The joint-gut axis in inflammatory bowel diseases

Inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are associated with a variety of extraintestinal manifestations. The most common extraintestinal manifestation, articular involvement, occurs in 16% to 33% of inflammatory bowel disease patients. These arthropathies may increase morbidity, resulting in a worse quality of life compared with inflammatory bowel disease patients without arthropathies. Thus, arthropathies in inflammatory bowel diseases represent a major medical problem in these patients. Arthritis associated with inflammatory bowel diseases is one of the diseases captured under the umbrella of spondyloarthritis. Spondyloarthritis is a group of inflammatory diseases with overlapping features and is linked to Human Leukocyte Antigen-B27. Arthropathy in inflammatory bowel diseases is clinically divided into peripheral and axial involvement. Peripheral arthritis often flares with relapses of bowel disease resulting in a different treatment approach than axial arthritis in which the course is independent of inflammatory bowel disease activity. Definitions, prevalence, pathophysiology and treatment of the arthropathies commonly seen in inflammatory bowel diseases such as peripheral arthritis, dactylitis, enthesitis, arthralgia, sacroiliitis, inflammatory back pain and ankylosing spondylitis are summarized.

Mucosal biomarkers in inflammatory bowel disease: Key pathogenic players or disease predictors?

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the bowel, including ulcerative colitis and Crohn’s disease. A single etiology has not been identified, but rather the pathogenesis of IBD is very complex and involves several major and minor contributors, employing different inflammatory pathways which have different roles in different patients. Although new and powerful medical treatments are available, many are biological drugs or immunosuppressants, which are associated with significant side effects and elevated costs. As a result, the need for predicting disease course and response to therapy is essential. Major attempts have been made at identifying clinical characteristics, concurrent medical therapy, and serological and genetic markers as predictors of response to biological agents. Only few reports exist on how mucosal/tissue markers are able to predict clinical behavior of the disease or its response to therapy. The aim of this paper therefore is to review the little information available regarding tissue markers as predictors of response to therapy, and reevaluate the role of tissue factors associated with disease severity, which can eventually be ranked as “tissue factor predictors”. Five main categories are assessed, including mucosal cytokines and chemokines, adhesion molecules and markers of activation, immune and non-immune cells, and other mucosal components. Improvement in the design and specificity of clinical studies are mandatory to be able to classify tissue markers as predictors of disease course and response to specific therapy, obtain the goal of achieving “personalized pathogenesis-oriented therapy” in IBD.

Joint involvement in inflammatory bowel disease: managing inflammation outside the digestive system

Joint inflammation is present in approximately 30% of patients with inflammatory bowel disease. Peripheral arthritis can frequently be controlled by an optimal treatment of the gut inflammation in association with short-term use of NSAIDs. Recurrent inflammation requires the use of sulfasalazine. More therapy-resistant forms and axial arthropathy can be treated with anti-TNF drugs, predominantly infliximab and adalimumab. An intensified multidisciplinary approach in research and in the clinic may help to unravel the question of why common etiopathogenic mechanisms ultimately lead to different disease phenotypes. Animal models may help to identify the most promising therapeutic strategies including in the near future modulation of adhesion molecules, costimulatory molecules and the Th17 pathway.

Progress in spondylarthritis. Immunopathogenesis of spondyloarthritis: which cells drive disease?

Spondyloarthritides, or SpA, form a cluster of chronic inflammatory diseases with the axial skeleton as the most typical disease localisation, although extra-articular manifestations such as intestinal inflammation may frequently occur during the course of the disease. This review summarises recent progress in our understanding of the immunopathogenesis of SpA with special emphasis on the cellular constituents considered to be responsible for the initiation and/or perpetuation of inflammation. There are several arguments favouring a role for haematopoietic cells in the pathophysiology of spondyloarthritis, including HLA-B27-associated dendritic cell disturbances, HLA-B27 misfolding properties and T helper 17 cells. In addition, recent studies have pointed toward a pivotal role for stromal cells. A major challenge, however, remains to determine how recently identified genetic associations such as interleukin-23 receptor polymorphisms may influence cellular targets in spondyloarthritis.

Indications and challenges of probiotics, prebiotics, and synbiotics in the management of arthralgias and spondyloarthropathies in inflammatory bowel disease

Arthralgia and spondyloarthropathy of the peripheral and the axial joints are common in patients with inflammatory bowel diseases. Evidence for this association has been provided by clinical, epidemiologic, and immunologic studies confirming the presence of shared inflammatory pathways in gut and joint. Bacterial gut infections such as Salmonella typhimurium, Yersinia enterocolitica, Shigella, Campylobacter jejuni may induce reactive peripheral arthritis and 20% of these patients may develop chronic spondyloarthropathy. It is not certain that arthralgias in inflammatory bowel diseases are more frequent than in the general population but clinical articular manifestations compatible with spondyloarthropathy are present in 10% to 40% of patients with inflammatory bowel diseases. These enteropathic peripheral arthropathies without axial involvement are subdivided into a pauciarticular of large joints and a bilateral symmetrical polyarthropathy. The rationale and the challenges of using prebiotics, probiotics, and synbiotics in the management of patients with inflammatory bowel diseases with arthralgias and spondyloarthropathy are briefly reviewed. The rationale is based on the modulation of the ubiquitous intestinal flora by bacteria and their products that have been proven to be safe. The challenge is to find the "window of opportunity" to treat the evolutionary stage of joint inflammation. It seems to us that the major aim is not to treat patients who have a self-limited inflammatory joint disorder, but those patients with persistent arthralgias in an early phase of the disease. Seronegative and seropositive patients with early arthritis, before damage may occur, could be managed by this approach to improve the quality of life and to positively influence the natural course of the disease.

Joint expedition: linking gut inflammation to arthritis

The tight connection between intestinal inflammation and arthritis in spondyloarthritis (SpA) has been studied extensively. Subclinical gut inflammation, which can be considered as a model for early Crohn's disease, was shown to be strongly associated with joint inflammation. Several early mucosal abnormalities were uncovered even in the absence of histological signs of inflammation, providing clues into the pathogenesis of SpA. Nevertheless, many questions remain unanswered. In this review, we highlight recent progress on this intimate relationship between gut and joint inflammation. Emerging evidence exists favoring a role for genes beyond human leukocyte antigen B27 in the genetic predisposition of SpA and intestinal inflammation. Furthermore, the role of these predisposing genes in modulating host-pathogen interaction at mucosal surfaces and the subsequent link between gut and joint inflammation are of utmost importance in understanding the pathogenesis of SpA.

Emergence of Crohn's disease during treatment with the anti-tumor necrosis factor agent etanercept for ankylosing spondylitis: possible mechanisms of action

OBJECTIVES

To report on the clinical evolution of a patient with ankylosing spondylitis (AS) treated with etanercept who subsequently developed Crohn's disease, to review the literature for similar cases, and to discuss possible mechanisms responsible for these observations.

METHODS

We describe the medical history, diagnostic tests, and disease progression of a 26-year-old man with AS who developed the clinical manifestations of Crohn's disease after 16 months of successful treatment of his rheumatologic symptoms with etanercept. A Medline search, as well as cases presented in abstract form at European Leaque Against Rheumatism (EULAR) and American College of Rheumotology (ACR) meetings, describing emergent bowel symptoms in patients treated with etanercept was undertaken.

RESULTS

Eight other cases were identified, with gastrointestinal symptoms appearing after a few weeks to several years, while receiving etanercept treatment. These observations raise the possibility that etanercept unmasks inflammatory bowel disease in patients with AS whose gastrointestinal symptoms were silent.

CONCLUSION

The reactivation or the unmasking of gastrointestinal symptoms during etanercept treatment raises the issue of differences between etanercept and the other antitumor necrosis factor monoclonal antibodies in their molecular structure, tumor necrosis factor neutralizing effect, mode of administration, and pharmacokinetics that may account for these observations.

Gene expression analysis of macrophages derived from ankylosing spondylitis patients reveals interferon-gamma dysregulation

OBJECTIVE

To determine whether macrophages, a type of cell implicated in the pathogenesis of ankylosing spondylitis (AS), exhibit a characteristic gene expression pattern.

METHODS

Macrophages were derived from the peripheral blood of 8 AS patients (median disease duration 13 years [range <1-43 years]) and 9 healthy control subjects over 7 days with the use of granulocyte-macrophage colony-stimulating factor. Cells were stimulated for 24 hours with interferon-gamma (IFN gamma; 100 units/ml), were left untreated for 24 hours, or were treated for 3 hours with lipopolysaccharide (LPS; 10 ng/ml). RNA was isolated and examined by microarray and real-time quantitative reverse transcription-polymerase chain reaction analysis.

RESULTS

Microarray analysis revealed 198 probe sets detecting the differential expression of 141 unique genes in untreated macrophages from AS patients compared with healthy controls. Clustering and principal components analysis clearly distinguished AS patients and controls. Of the differentially expressed genes, 78 (55%) were IFN-regulated, and their relative expression indicated a "reverse" IFN signature in AS patient macrophages, where IFN gamma-up-regulated genes were underexpressed and down-regulated genes were overexpressed. Treatment of macrophages with exogenous IFN gamma normalized the expression of these genes between patients and controls. In addition, the messenger RNA encoded by the IFN gamma gene was approximately 2-fold lower in AS patient macrophages at baseline (P = 0.004) and was poorly responsive to LPS (P = 0.018), as compared with healthy controls.

CONCLUSIONS

Our findings reveal consistent differences in gene expression in macrophages from AS patients, with evidence of a striking "reverse" IFN signature. Together with poor expression and responsiveness of the IFN gamma gene, these results suggest that there may be a relative defect in IFN gamma gene regulation, with autocrine consequences and implications for disease pathogenesis.

Mucosal macrophages and the regulation of immune responses in the intestine

The healthy intestinal mucosa is home to one of the largest populations of macrophages (mvarphi) in the body [Lee SH, Starkey PM, Gordon S. Quantitative analysis of total macrophage content in adult mouse tissues. Immunochemical studies with monoclonal antibody F4/80. J Exp Med 1985;161:475-89], yet little is known about their function. Resident mvarphi in the large and small intestine are distinct from other mvarphi populations in the body, with regards to both their functional properties and surface phenotype. They respond in an unconventional manner to inflammatory stimuli, with little upregulation of proteins involved in antigen presentation and T cell co-stimulation, and no production of pro-inflammatory cytokines. This suggests that under resting conditions, intestinal mvarphi may be conditioned to be anti-inflammatory in response to local stimuli such as commensal bacteria. In contrast, during inflammation, intestinal mvarphi exhibit increased bactericidal and inflammatory abilities, promote protective immunity and/or mediate pathology. Thus the status of this cell may be the key to understanding how the intestine maintains a balance between being able to generate protective immunity against pathogens, but still prevent pathological inflammation under normal conditions. In this review, we discuss the current knowledge of intestinal mvarphi biology, and highlight the different levels of immunoregulation which influence these cells, with particular focus on innate pathogen recognition receptor (PRR) function and responsiveness to microbial stimuli.

Tumor-infiltrating macrophages and dendritic cells in human colorectal cancer: relation to local regulatory T cells, systemic T-cell response against tumor-associated antigens and survival

Introduction

Although systemic T-cell responses against tumor antigens and tumor infiltration by T cells have been investigated in colorectal cancer (CRC), the initiation of spontaneous immune responses in situ is not well understood. Macrophages and dendritic cells (DC) play an important role as a link between innate and adaptive immune response. The aim of the present study was to analyze macrophage and DC infiltration in CRC and to investigate whether there is a correlation to systemic T-cell response, regulatory T cell (Treg) infiltration, and survival.

Methods

Immunohistological staining was performed with nine markers for macrophages and DC (CD68, CD163, S100, CD11c, CD208, CD209, CD123, CD1a, Langerin) in 40 colorectal cancer samples from patients, in whom the state of systemic T-cell responses against tumor-associated antigens (TAA) and Treg infiltration had previously been determined.

Results

All specimens contained cells positive for CD68, CD163, S100 and CD1a in epithelial tumor tissue and tumor stroma. Only a very few (less than median 3/HPF) CD123+, CD1a+, CD11c+, CD 208+, CD209+, or Langerin+ cells were detected in the specimens. Overall, we found a trend towards increased infiltration by S100-positive DC and a significantly increased number of stromal S100-positive DC in patients without T-cell response. There was an increase of stromal S100 DC and CD163 macrophages in limited disease (S100: 11.1/HPF vs. 7.3/HPF, p = 0.046; CD163: 11.0/HPF vs. 8.1/HPF, p = 0.06). We found a significant, positive correlation between S100-positive DC and FOXP3-positive Tregs. Survival in patients with high DC infiltration was significantly better than that in those with low DC infiltration (p < 0.05). Furthermore, we found a trend towards better survival for increased infiltration with CD163-positive macrophages (p = 0.07).

Conclusion

The present in situ study adds new data to the discussion on the interaction between the innate and adoptive immune system. Our data strongly support the hypothesis that tumor-infiltrating DC are a key factor at the interface between innate and adaptive immune response in malignant disease. Tumor infiltrating S100-positive DC show an inverse relationship with the systemic antigen-specific T-cell response, a positive correlation with regulatory T cells, and a positive association with survival in CRC. These data put tumor-infiltrating DC at the center of the relevant immune response in CRC.

The intimate relationship between gut and joint in spondyloarthropathies

PURPOSE OF REVIEW

The aim of this article is to highlight recent progress in the combined joint and gut disease in spondyloarthropathies.

RECENT FINDINGS

A set of genes has been identified that are differentially expressed in the colon of spondyloarthropathy and Crohn's disease patients. Reduction of human leukocyte antigen B27 (HLA B27) misfolding by additional beta2-microglobulin in HLA B27 transgenic rats unexpectedly increased disease severity, with more similarities to spondyloarthropathies. By contrast, colitis disappeared.

SUMMARY

Human genomic studies combined with animal model research provide new clues concerning the common pathogenesis of spondyloarthropathy and Crohn's disease, further substantiating the unique relationship between gut and joint inflammation.