Detection of Chlamydia trachomatis in peripheral blood leukocytes of reactive arthritis patients by polymerase chain reaction

[History of reactive arthritis. Historical milestones and future]

The introduction of the term reactive arthritis (ReA) for the joint inflammation observed after infection with Yersinia enterocolitica, in which "a causative pathogen cannot be isolated from the synovial fluid", and the association with the HLA-B27 were the historical milestones for a new classification and assignment to the spondylarthritides (SpA). The division into postinfectious and reactive arthritis proposed in 1976 was put into perspective in the 1990s because of investigations with the newly available molecular biological method of the polymerase chain reaction. Microbial products could be identified from joint samples of patients with ReA. Therefore, it was proposed to abandon the distinction between the two groups of diseases and to prefer the term ReA for both. This created a terminological and nosological issue. On the one hand, there are generally accepted classification and diagnostic criteria for the classical HLA-B27-associated ReA that are assigned to SpA. On the other hand, an increasing number of bacterial pathogens, viruses, amoebas, helminths as well as antiviral and antibacterial vaccinations are described as triggers of arthritis, which have been published under the term ReA. Since the beginning of the SARS-CoV‑2 pandemic, cases of acute post-COVID-19 arthritis have been described, which were also classified as ReA because of comparable clinical features.

Putative Pathobionts in HLA-B27-Associated Spondyloarthropathy

Spondyloarthritis (SpA) is a group of immune mediated inflammatory diseases with a strong association to the major histocompatibility (MHC) class I molecule, HLA-B27. Although the association between HLA-B27 and AS has been known for almost 50 years, the mechanisms underlying disease pathogenesis are elusive. Over the years, three hypotheses have been proposed to explain HLA-B27 and disease association: 1) HLA B27 presents arthritogenic peptides and thus creates a pathological immune response; 2) HLA-B27 misfolding causes endoplasmic reticulum (ER) stress which activates the unfolded protein response (UPR); 3) HLA-B27 dimerizes on the cell surface and acts as a target for natural killer (NK) cells. None of these hypotheses explains SpA pathogenesis completely. Evidence supports the hypothesis that HLA-B27-related diseases have a microbial pathogenesis. In animal models of various SpAs, a germ-free environment abrogates disease development and colonizing these animals with gut commensal microbes can restore disease manifestations. The depth of microbial influence on SpA development has been realized due to our ability to characterize microbial communities in the gut using next-generation sequencing approaches. In this review, we will discuss various putative pathobionts in the pathogenesis of HLA-B27-associated diseases. We pursue whether a single pathobiont or a disruption of microbial community and function is associated with HLA-B27-related diseases. Furthermore, rather than a specific pathobiont, metabolic functions of various disease-associated microbes might be key. While the use of germ-free models of SpA have facilitated understanding the role of microbes in disease development, future studies with animal models that mimic diverse microbial communities instead of mono-colonization are indispensable. We discuss the causal mechanisms underlying disease pathogenesis including the role of these pathobionts on mucin degradation, mucosal adherence, and gut epithelial barrier disruption and inflammation. Finally, we review the various uses of microbes as therapeutic modalities including pre/probiotics, diet, microbial metabolites and fecal microbiota transplant. Unravelling these complex host-microbe interactions will lead to the development of new targets/therapies for alleviation of SpA and other HLA-B27 associated diseases.

Chlamydia Trachomatis Associated Reactive Arthritis: A Urinary PCR Based Study

Background and Objective:

Chlamydia trachomatis is increasingly being associated with reactive arthritis (ReA). The present study was undertaken to assess the role of C. trachomatis in patients with ReA since such data is lacking from the Indian population.

Materials and Methods:

PCR using specific primers for C. trachomatis was carried out from urine samples of 65 patients with ReA, 20 of other inflammatory arthritis, and 20 healthy controls.

Results:

C. trachomatis DNA was detected from urinary samples with PCR in 24 (36%) of 65 ReA patients. PCR was negative in the patients of other inflammatory arthritis as well as in normal healthy control group. Out of the 24 patients with urinary PCR positivity, 14 (58.33%) were males and 10 (41.66%) were females.

Conclusion:

Urinary PCR plays an important role in rapid diagnosis of ReA associated with C. trachomatis.

Evolving patterns of reactive arthritis

OBJECTIVE

To characterize rheumatologists' perspectives on evolving trends of reactive arthritis (ReA).

METHODS

After ethics approval, 548 members of the Canadian Rheumatology Association were surveyed with 37 questions covering their demographic information, subspecialty, level of experience, practice setting and opinions on prevalence, treatment, and causes of ReA. Results were analyzed with descriptive statistics.

RESULTS

Ninety-seven responded to the survey (18% response rate); 66 fully completed it. Nearly half of respondents believed that the incidence of ReA is declining and causes of ReA may be changing. Physicians reported that most of the ReA cases in their practices were caused by an unknown organism, sexually transmitted, or gastrointestinal infection. Full triad ReA increased the chance of recurrence according to their impressions. Common investigations in ReA included inflammatory markers, HLA-B27, chlamydia and gonorrhea testing, stool cultures, synovial fluid analyses, SI joint imaging. ReA treatment included NSAIDs, intra-articular corticosteroid injections, and DMARDs. Two-thirds said they used TNF alpha inhibitors in chronic ReA occasionally or more frequently.

CONCLUSION

ReA may be decreasing in frequency and severity in Canada. Changes could be due to less food borne illness, cleaner water, or more rapid treatment of sexually transmitted infections. The cause is often unknown in clinical practice.Key Points• Reactive arthritis (ReA) is likely decreasing in prevalence and severity.• Patients with classic trial of arthritis, urethritis, and conjunctivitis are more likely to have recurrent and/or chronic ReA.• The causal organisms are often not detected and seem to be changing over time.

Coinfection of Chlamydiae and other Bacteria in Reactive Arthritis and Spondyloarthritis: Need for Future Research

Reactive (inflammatory) arthritis has been known for many years to follow genital infection with the intracellular bacterial pathogen Chlamydia trachomatis in some individuals. Recent studies from several groups have demonstrated that a related bacterium, the respiratory pathogen Chlamydia pneumoniae, can elicit a similar arthritis. Studies of these organisms, and of a set of gastrointestinal pathogens also associated with engendering inflammatory arthritis, have been relatively extensive. However, reports focusing on coinfections with these and/or other organisms, and the effects of such coinfections on the host immune and other systems, have been rare. In this article, we review the extant data regarding infections by multiple pathogens in the joint as they relate to engendering arthritis, and we suggest a number of research areas that must be given a high priority if we are to understand, and therefore to treat in an effective manner, such arthritides.

Ultrasonography Role in Evaluation of Achilles Tendon Enthesis in Reactive Arthritis Patients

Reactive arthritis is an inflammatory joint disease which develops after 1-4 weeks following an enteral, genital or ORL infection, with a higher frequency in HLA-B27 positive patients. As a group feature, enthesitis is defined as inflammation in bone insertions of tendons, ligaments and muscular fascia. Aims: the main object of this study was to demonstrate the importance of musculoskeletal ultrasonography in Achilles tendon evaluation in patients with reactive arthritis. Patients and methods: we designed a transversal, retrospective study which included 15 patients diagnosed, based on ESSG criteria, with reactive arthritis (ReA), in Rheumatology Department, Emergency County Hospital. From those 15 patients, 9 were positive for a genital infection with Chlamydia trachomatis and 6 patients with enteral infection, 2 with Shigella, respectively 4 with Yersinia. Healthy control group included 15 patients, with no inflammatory joint diseases. After clinical examination, all patients and controls underwent ultrasound (US) evaluation for Achilles tendon changes, using an Esaote MyLab 25 machine, with a linear high frequency probe (10-18 MHz), using EULAR recommendations and OMERACT definitions for enthesitis, tendinitis and erosions. The cutoff value for the Achilles tendon thickness was 5.29mm, as described by Balint et al. Results: We examined 30 Achilles tendons in 15 patients, with a mean age of 35,2years±10,19 standard deviation (SD) and 30 tendons in 15 controls with a mean age of 35,8 years ±12,00 SD. In both groups sex prevalence showed more males than females (66,66% males in controls vs. 60,00% in patients group). We found a statistic significant higher ESR and CRP in patients group, compared to controls (24,86mm/h vs. 11,8mm/h; 18.90mg/dl vs. 6.22mg/dl). Most frequent finding in patients group was retrocalcaneal bursitis (56.66%), followed by tendon thickening (46.66%), compared to control group in which we found more frequently osteophytes (36.66%) and calcifications (23.33%). Tendon thickness was significantly higher in the patients group compared to control group 5.30mm±1.39SD vs. 4.42mm±0.77SD, p=0.008). When compared to clinical examination, US found at least one change in all patients (100% vs. 40.0%). Conclusions: A higher prevalence of retrocalcaneal bursitis and tendon thickening were found in reactive arthritis patients compared to control group. The US found more changes compared to clinical examination and manage to discriminate between the types of changes found more frequently in inflammatory conditions.

Imbalanced oxidative stress causes chlamydial persistence during non-productive human herpes virus co-infection

Both human herpes viruses and Chlamydia are highly prevalent in the human population and are detected together in different human disorders. Here, we demonstrate that co-infection with human herpes virus 6 (HHV6) interferes with the developmental cycle of C. trachomatis and induces persistence. Induction of chlamydial persistence by HHV6 is independent of productive virus infection, but requires the interaction and uptake of the virus by the host cell. On the other hand, viral uptake is strongly promoted under co-infection conditions. Host cell glutathione reductase activity was suppressed by HHV6 causing NADPH accumulation, decreased formation of reduced glutathione and increased oxidative stress. Prevention of oxidative stress restored infectivity of Chlamydia after HHV6-induced persistence. We show that co-infection with Herpes simplex virus 1 or human Cytomegalovirus also induces chlamydial persistence by a similar mechanism suggesting that Chlamydia -human herpes virus co-infections are evolutionary shaped interactions with a thus far unrecognized broad significance.

Heavy metal exposure reverses genetic resistance to Chlamydia-induced arthritis

INTRODUCTION

We have previously observed that Brown Norway (BN) rats display a relative resistance to experimental Chlamydia-induced arthritis. In the present study, we examine an environmental toxin, mercuric chloride (HgCl2), as a modulator of this innate resistance to arthritis.

METHODS

To assess the effect of the heavy metal exposure, one group of rats received two subcutaneous injections of HgCl2 (1 mg/kg) 48 hours apart. Seven days later, the animals received the intra-articular injection of synoviocyte-packaged Chlamydia.

RESULTS

Histopathology revealed that BN rats receiving only Chlamydia had a minimal cellular infiltration in the joint, which was predominantly mononuclear in character. In contrast, mercury-exposed rats had a marked exacerbation of the histopathological severity of the arthritis, and the infiltration was predominantly neutrophilic. Mercury exposure was also associated with marked enhancement in IgE levels and an alteration in IgG2a/IgG1 ratio, reflecting a Th2 shift. The local cytokine profile in the joint was markedly altered after mercury exposure, with a suppression of tumour necrosis factor-alpha and interferon-gamma but an enhancement of vascular endothelial growth factor. This was associated with decreased host clearance capacity reflected in enhanced bacterial load in both the spleen and the joint and was accompanied by enhanced detection of microbial antigens in the synovial tissues by immunohistological staining.

CONCLUSIONS

Genetically defined cytokine production in the joint defines the severity of reactive arthritis by dictating the local clearance of the pathogen. This interplay can be altered dramatically by heavy metal exposure, which results in suppression of protective cytokines in the microenvironment of the joint.

Peptidomic analysis of human peripheral monocytes persistently infected by Chlamydia trachomatis

Peptidomic analysis using Differential Peptide Display (DPD) of human peripheral blood mononuclear cells (PBMC) mock-infected or persistently infected by Chlamydia trachomatis (CT) revealed 10 peptides, expressed upon CT infection. Analysis of these 10 candidates by tandem mass spectrometry enabled the determination of seven candidates as fragments from the precursors (I) ferritin heavy chain subunit, (II) HLA class II histocompatibility antigen, (III) vimentin, (IV) indoleamine 2,3-dioxygenase, (V and VI) pre-B cell enhancing factor (PBEF), and (VII) Interleukin-8 (CXCL8). The identified candidates proved the presence of anti-bacterial and immunologically active monocytic proteins after CT infection.

When is arthritis reactive?

Reactive arthritis is an important cause of lower limb oligoarthritis, mainly in young adults. It is one of the spondyloarthropathy family; it is distinguishable from other forms of inflammatory arthritis by virtue of the distribution of affected sites and the high prevalence of characteristic extra-articular lesions. Many terms have been used to refer to this and related forms of arthritis leading to some confusion. Reactive arthritis is precipitated by an infection at a distant site and genetic susceptibility is marked by possession of the HLA-B27 gene, although the mechanism remains uncertain. Diagnosis is a two stage process and requires demonstration of a temporal link with a recognised "trigger" infection. The identification and management of "sexually acquired" and "enteric" forms of reactive arthritis are considered. Putative links with HIV infection are also discussed. The clinical features, approach to investigation, diagnosis, and management of reactive arthritis are reviewed.

Mechanisms of disease: infection and spondyloarthritis

There is compelling evidence that some infections can initiate a chronic nonseptic arthritis. This has proved to be an important area of investigation into gene-environment interactions, particularly since HLA-B27 confers increased susceptibility to reactive arthritis. This research has investigated the microbiology of these events, and the strategies used by pathogens to induce chronic joint inflammation. Insights into the HLA-orchestrated immune response in this context have also shed light on the impact of HLA-B27 on immunity, which might provide insights into the mechanism of other HLA-B27-associated diseases. Despite the genetic link to reactive arthritis, there is no proven relationship between ankylosing spondylitis and an inciting infection. In general, most trials have found antibiotics to be ineffective in modifying the course of spondyloarthritis.

Pathogenesis of ankylosing spondylitis and reactive arthritis

PURPOSE OF REVIEW

The hallmark of ankylosing spondylitis is acute and chronic spinal inflammation initiating in the sacroiliac joints, often coupled with enthesitis, presenting as chronic inflammation at the sites of ligamentous and tendinous insertions into bone. Peripheral joint synovitis can be a prominent feature as well. Reactive arthritis is a sterile synovitis arising after an extra-articular infection of enteric or urogenital tracts. HLA-B27 has been known for about the past 30 years to be associated with ankylosing spondylitis and reactive arthritis, but the pathogenesis of ankylosing spondylitis and reactive arthritis is still not well defined. Although the clinical manifestations of ankylosing spondylitis and reactive arthritis may differ, this update discusses the two diseases together and focuses on recent evidence in both.

RECENT FINDINGS

With respect to HLA-B27 several recent studies address arthritogenic peptides, molecular mimicry, and aberrant forms of B27. Several candidate genes in addition to B27 have been implicated in recent genetic studies. With respect to bacterial infection, recent findings in bacterial antigenicity, host response through interactions of antigen-presenting cells, T cells, and cytokines are providing new understanding of host-pathogen interactions and the pathogenesis of arthritis. Endogenous host factors such as proteoglycans may play a role as autoantigens and contribute to chronic inflammation on that basis.

SUMMARY

Recent advances provide additional new insights into distinct pathogenetic mechanisms in AS and ReA that arise from a complex interplay between genetic factors including HLA-B27 and environmental factors.

Production of prostaglandin E2 in monocytes stimulated in vitro by Chlamydia trachomatis, Chlamydophila pneumoniae, and Mycoplasma fermentans

Chlamydia trachomatis (CT) as well as Chlamydophila pneumoniae (CP) cause chronic inflammatory diseases in humans. Persistently infected monocytes are involved in the pathogenesis by inducing mediators of inflammation. An in vitro system of chlamydial persistence in human peripheral blood monocytes (HPBM) was used to investigate prostaglandin E(2) (PGE(2)) production and the expression of the key enzyme for prostaglandin production, cyclooxygenase-2 (COX-2). PGE(2) production was determined by PGE(2)-ELISA of HPBM-culture supernatants. Cox-2 mRNA expression was measured by real-time RT-PCR of total RNA isolated from HPBM. Both, CT and CP, stimulated PGE(2) production of HPBM in vitro. Equivalent numbers of CT per host cell induced a higher PGE(2)-response compared to CP. The amount of synthesized PGE(2) depended on the chlamydial multiplicity of infection (MOI). Even at an MOI of 10 the amount of CT- and CP-induced prostaglandin, respectively, was lower than the amount of prostaglandin induced by E. coli lipopolysaccharide (LPS) at a concentration of 10microg/ml. In contrast to stimulation with LPS, Chlamydia-induced PGE(2) production as well as cox-2 mRNA decreased after day 1 post infection (p.i.). These data indicate that Chlamydia stimulate PGE(2) production in human monocytes. Since Chlamydia are often contaminated by mycoplasma, the influence of mycoplasma on the prostaglandin production was investigated additionally. Mycoplasma fermentans (MF) also stimulated PGE(2) production. The co-infection of mycoplasma and Chlamydia resulted in an additive effect in the production of PGE(2). Thus it is important to use host cells and Chlamydia free of mycoplasma contamination for the analysis of Chlamydia-induced prostaglandin production.

HLA-B27-associated reactive arthritis: pathogenetic and clinical considerations

Current evidence supports the concept that reactive arthritis (ReA) is an immune-mediated synovitis resulting from slow bacterial infections and showing intra-articular persistence of viable, non-culturable bacteria and/or immunogenetic bacterial antigens synthesized by metabolically active bacteria residing in the joint and/or elsewhere in the body. The mechanisms that lead to the development of ReA are complex and basically involve an interaction between an arthritogenic agent and a predisposed host. The way in which a host accommodates to invasive facultative intracellular bacteria is the key to the development of ReA. The details of the molecular pathways that explain the articular and extra-articular manifestations of the disease are still under investigation. Several studies have been done to gain a better understanding of the pathogenesis of ReA; these constitute the basis for a more rational therapeutic approach to this disease.

How does Chlamydia cause arthritis?

Because the bacterial cause of CIA has been identified and proven to persist at the site of inflammation, the understanding of how Chlamydia cause arthritis has made much progress. The site of entry and the route of dissemination have been identified, the molecular state of persistence is increasingly described, some mechanisms of how Chlamydia can persist despite an actively reacting immune system have been identified, and data regarding how persistent Chlamydia induce inflammation have been obtained. What needs to be achieved in the future--in addition to better understanding the molecular basis of persistence--is to reveal how persisting bacteria can be eliminated. If this information is insufficient for a cure of the disease, it must be determined how the inflammation can be treated more specifically and effectively to cure CIA early and prevent the development of chronic forms that develop into spondyloarthritis.

Role of bacteria and HLA-B27 in the pathogenesis of reactive arthritis

Strictly speaking, "reactive arthritis" is a conventional term with no study-verified definition. This review will focus on the type of arthritis that is induced by the following species: Chlamydia, Shigella, Salmonella, Yersinia, and Campylobacter. The types of arthritis caused by these pathogens share a clinical pattern that is common in the spondyloarthropathies, especially undifferentiated spondyloarthropathy and Reiter's syndrome. All these diseases, including ankylosing spondylitis, must also share major pathogenetic pathways.

Reactive arthritis or chronic infectious arthritis?

Microbes reach the synovial cavity either directly during bacteraemia or by transport within lymphoid cells or monocytes. This may stimulate the immune system excessively, triggering arthritis. Some forms of ReA correspond to slow infectious arthritis due to the persistence of microbes and some to an infection triggered arthritis linked to an extra-articular site of infection.

Pathogenesis of reactive arthritis

There is good evidence that bacteria persist in vivo in patients with reactive arthritis (ReA). While Chlamydia seem to hide inside the joint, other areas such as gut mucosa or lymph nodes seem to be more likely places for Salmonella and Yersinia. T-helper (Th) 1 cells secreting cytokines such as IFN gamma and TNF alpha are crucial for an effective elimination of these bacteria. An inhibited Th1-response could be demonstrated in ReA, probably contributing to bacterial persistence. While HLA-B27 is found in only approximately 50% of patients with acute ReA, HLA-B27 seems to be crucial for the development of features typical with chronic spondyloarthropathy, such as sacroiliitis. Among several hypotheses to explain the interaction of bacteria with HLA-B27, the most likely seems to be that until now unknown bacterial or self- antigens were presented by HLA-B27 to CD8(+) T-cells. An important site where the immunopathology takes place seems to be at the insertion of tendons and ligaments at bone. Because antibiotics have failed so far in the treatment of ReA immunomodulatory therapies, based on a better understanding of the pathogenesis, alone or in combination with antibiotics might be an option for the future.

Insights into the Role of Infection in the Spondyloarthropathies

Certain infections play an important role in the pathogenesis of the human leukocyte antigen (HLA)-B27-associated reactive arthritis. Whether infections play a role in other forms of spondyloarthropathies is not as clear. The role of HLA-B27 as an antigen-presenting molecule is important in the pathogenesis of these diseases. Recent evidence has been obtained indicating that this molecule may have other functions unrelated to antigen-presentation in the interaction of reactive arthritis-triggering microbes and host. This paper reviews the recent studies on the role of infection in the spondyloarthropathies.

Expression of host defense scavenger receptors in spondylarthropathy

OBJECTIVE

Reactive arthritis (ReA) is postulated to be caused by a defective host defense against gram-negative bacteria. HLA-B27 could play a role in this process, but does not account for the many HLA-B27 negative patients. The objective of this study was to test the expression of 3 macrophage scavenger receptors (SRs) that are responsible for innate immunity against gram-negative bacteria: SR class A type I (SR-AI), SR-AII, and the macrophage receptor with collagenous structure (MARCO). We postulate that defects in such receptors might also contribute to the host risk factors that increase the predisposition to ReA and perhaps other subtypes of spondylarthropathy (SpA).

METHODS

Peripheral blood, synovial fluid, and synovial tissue samples were obtained from patients with recent Salmonella infection, ReA, other SpA, and rheumatoid arthritis (RA). The expression of SRs receptors was assessed by semiquantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Evaluation of the peripheral blood mononuclear cells (PBMC) from 4 patients who were recently infected with Salmonella, showed that PBMC from 2 patients who developed ReA expressed positive levels of MARCO, while PBMC from 2 patients who recovered from infection without sequelae did not. The synovial fluid mononuclear cells (SFMC) from some ReA patients expressed MARCO, but the levels were only moderate. The level of MARCO in the SFMC from the SpA patient group was low. In marked contrast, MARCO expression was high in almost all samples of RA SFMC. These findings also extended to synovial tissues.

CONCLUSION

Expression of the host defense gene MARCO was susceptible to modulation, not only during infections, but also in the inflammatory arthritis conditions RA and SpA. MARCO is a variable to be considered as a candidate factor that might contribute to ReA.

Reactive arthritis

During the past year, no big advances were reported in understanding the pathogenesis or treatment of reactive arthritis (ReA). The need for generally accepted diagnostic criteria has become a central issue. Regarding pathogenesis, attention has been drawn to a similarity between ReA and the experimental antigen-induced arthritis. Molecular mechanisms of the HLA-B27-associated pathogenesis have remained, in spite of intensive research, so far a mystery. It is apparent that antibiotics have no effect on the fully developed reactive arthritis, with the exception of patients with Chlamydia-triggered ReA, who might benefit from a course of antibiotics.