Recent advances and future directions in understanding and treating Chlamydia-induced reactive arthritis

Tracking Chlamydia - Host interactions and antichlamydial activity in Caenorhabditis elegans

The fading efficacy of antibiotics is a growing global health concern due to its life-threatening consequences and increased healthcare costs. Non-genetic mechanisms of antimicrobial resistance, such as those employed by Chlamydia pneumoniae and Chlamydia trachomatis, complicate treatment as these bacteria can enter a non-replicative, persistent state under stress, evading antibiotics and linking to inflammatory conditions. Understanding chlamydial persistence at the molecular level is challenging, and new models for studying Chlamydia-host interactions in vivo are urgently needed. Caenorhabditis elegans offers an alternative given its immune system and numerous orthologues of human genes. This study established C. elegans as an in vivo model for chlamydial infection. Both Chlamydia species reduced the worm's lifespan, their DNA being detectable at three- and six-days post-infection. Azithromycin at its MIC (25 nM) failed to prevent the infection-induced lifespan reduction, indicating a persister phenotype. In contrast, the methanolic extract of Schisandra chinensis berries showed anti-chlamydial activity both in vitro (in THP-1 macrophages) and in vivo, significantly extending the lifespan of infected C. elegans and reducing the bacterial load. Moreover, S. chinensis increased the transcriptional activity of SKN-1 in the worms, but was unable to impact the bacterial load or lifespan in a sek-1 defective C. elegans strain. In summary, this study validated C. elegans as a chlamydial infection model and showcased S. chinensis berries' in vivo anti-chlamydial potential, possibly through SEK/SKN-1 signaling modulation.

Distinct characteristics of the gut virome in patients with osteoarthritis and gouty arthritis

BACKGROUND/PURPOSE(S)

The gut microbiota and its metabolites play crucial roles in pathogenesis of arthritis, highlighting gut microbiota as a promising avenue for modulating autoimmunity. However, the characterization of the gut virome in arthritis patients, including osteoarthritis (OA) and gouty arthritis (GA), requires further investigation.

METHODS

We employed virus-like particle (VLP)-based metagenomic sequencing to analyze gut viral community in 20 OA patients, 26 GA patients, and 31 healthy controls, encompassing a total of 77 fecal samples.

RESULTS

Our analysis generated 6819 vOTUs, with a considerable proportion of viral genomes differing from existing catalogs. The gut virome in OA and GA patients differed significantly from healthy controls, showing variations in diversity and viral family abundances. We identified 157 OA-associated and 94 GA-associated vOTUs, achieving high accuracy in patient-control discrimination with random forest models. OA-associated viruses were predicted to infect pro-inflammatory bacteria or bacteria associated with immunoglobulin A production, while GA-associated viruses were linked to Bacteroidaceae or Lachnospiraceae phages. Furthermore, several viral functional orthologs displayed significant differences in frequency between OA-enriched and GA-enriched vOTUs, suggesting potential functional roles of these viruses. Additionally, we trained classification models based on gut viral signatures to effectively discriminate OA or GA patients from healthy controls, yielding AUC values up to 0.97, indicating the clinical utility of the gut virome in diagnosing OA or GA.

CONCLUSION

Our study highlights distinctive alterations in viral diversity and taxonomy within gut virome of OA and GA patients, offering insights into arthritis etiology and potential treatment and prevention strategies.

Reactive arthritis after SARS-CoV-2 infection

SARS-CoV-2 has been recognised as a potential trigger of inflammatory arthritis in individuals with inflammatory rheumatic diseases as well as in previously unaffected individuals. However, new-onset arthritis after COVID-19 is a heterogeneous phenomenon that complicates differential diagnosis. For example, acute arthritis with features of viral arthritis has been reported after COVID-19, as has crystal-induced arthritis. Arthritides mimicking reactive arthritis (ReA) have also been described, but these patients often do not fulfil the typical features of ReA: several reports describe cases of patients older than 45 years at the onset of arthritis, and the characteristic genetic feature of ReA, HLA-B27, is rarely found. Because viral infections are much less likely to cause ReA than bacterial infections, and respiratory infections are rarely the cause of ReA, it is currently unknown whether SARS-CoV-2 can cause true ReA. Here, we report the case of a 30-year-old patient who presented with acute pain, swelling and redness in the left metatarsophalangeal (MTP) joint and ankle 7 days after resolution of a SARS-CoV-2 infection. Diagnostics revealed arthritis of the MTP2, synovitis of the upper ankle with significant joint effusion and peritendinitis of the flexor tendons. Based on the clinical manifestations and diagnostic test results, ReA appeared to be the most likely cause. A screening for typical ReA-associated infections was negative. The patient was treated with NSAIDs and intra-articular and systemic glucocorticoids. At a follow-up visit after discontinuation of glucocorticoids, the patient was symptom-free. Overall, we observed a ReA with typical clinical, genetic and patient characteristics after SARS-CoV-2 infection, and we conclude that a direct association with COVID-19 is highly plausible.

Quo vadis reactive arthritis?

PURPOSE OF REVIEW

We provide an overview of recent articles which describe new thinking regarding HLA-B27-associated reactive arthritis (ReA), including those additional infection-related arthritides triggered by microbes that often are grouped under the term ReA.

RECENT FINDINGS

With the advent and continuation of the pandemic, an increasing number of cases and case series of post-COVID-19 arthritis have been reported and classified as ReA. Further, arthritis after COVID-19 vaccination is a new entity included within the spectrum of ReA. New causative microorganisms identified in case reports include Clostridium difficile, Mycoplasma pneumoniae, Giardia lamblia, Leptospira , and babesiosis. SARS-CoV-2 is emerging as a significant etiologic agent for apparent ReA.

SUMMARY

It is now clear that comprehensive clinical and laboratory investigations, synovial fluid analyses, and close follow-up of patients all are essential to differentiate ReA from diseases that may present with similar clinical attributes. Further, and importantly, additional research is required to define the wide diversity in causative agents, epidemiology, and rare case presentations of these arthritides. Finally, new classification and diagnostic criteria, and updated treatment recommendations, are essential to the advancement of our understanding of ReA.

Comparison of immune checkpoint inhibitor-induced arthritis and reactive arthritis to inform therapeutic strategy

INTRODUCTION

Immune checkpoint inhibitor-induced inflammatory arthritis (ICI-IA) is a relatively new disease entity caused by ICI agents during cancer therapy. Reactive arthritis (ReA) is a well-known disease entity caused by urogenital or gastrointestinal bacterial infection or pneumonia. In this sense, ICI-IA and ReA are both defined by a reaction to a well-specified causal event. As a result, comparing these diseases may help to determine therapeutic strategies.

METHODS

We compared ICI-IA and ReA with special focus on pharmacological management. Specifically regarding treatment, we conducted a literature search of studies published in the PubMed database. Inclusion criteria were studies on treatment with non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids (GC), or disease modifying antirheumatic drugs (DMARDs) in ICI-IA or ReA. During systematic selection, 21 studies evaluating ICI-IA and 14 studies evaluating ReA were included.

RESULTS

In ICI-IA, prospective and retrospective studies have shown effects of non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoid (GC), sulfasalazine (SSZ), methotrexate (MTX), hydroxychloroquine (HCQ) and TNFi. In ReA, retrospective studies evaluated NSAIDs and GC. A randomized controlled trial reported the effect of SSZ, and a retrospective study reported the effect of MTX and SSZ in combination with tumor necrosis factor alpha inhibition (TNFi). For both entities, small case reports show treatment effects of interleukin 6 receptor inhibition (IL-6Ri).

DISCUSSION

This literature review identified both similarities and differences regarding the pathogenesis and clinical features of ReA and ICI-IA. Studies on treatment reported effectiveness of NSAIDs, GC, MTX, SSZ and TNFi in both diseases. Further, small case reports showed effects of IL-6Ri.

Chlamydia spreads to the large intestine lumen via multiple pathways

Chlamydia in the genital tract is known to spread via the blood circulation system to the large intestinal lumen to achieve long-lasting colonization. However, the precise pathways for genital Chlamydia to access to the large intestinal lumen remain unclear. The spleen was recently reported to be critical for the chlamydial spreading. In the current study, it was found that following intravaginal inoculation with Chlamydia, mice with or without splenectomy both produced infectious Chlamydia in the rectal swabs, indicating that spleen is not essential for genital Chlamydia to spread to the gastrointestinal tract. This conclusion was validated by the observation that intravenously inoculated Chlamydia was also detected in the rectal swabs of mice regardless of splenectomy. Careful comparison of the tissue distribution of live chlamydial organisms following intravenous inoculation revealed redundant pathways for Chlamydia to reach the large intestine lumen. The intravenously inoculated Chlamydia was predominantly recruited to the spleen within 12h and then detected in the stomach lumen by 24h, the intestinal lumen by 48h and rectal swabs by 72h. These observations suggest a potential spleen-to-stomach pathway for hematogenous Chlamydia to reach the large intestine lumen. This conclusion was supported by the observation made in mice under coprophagy-free condition. However, in the absence of spleen, hematogenous Chlamydia was predominantly recruited to the liver and then simultaneously detected in the intestinal tissue and lumen, suggesting a potential liver-to-intestine pathway for Chlamydia to reach the large intestine lumen. Thus, genital/hematogenous Chlamydia may reach the large intestinal lumen via multiple redundant pathways.

Reactive Arthritis Update: Spotlight on New and Rare Infectious Agents Implicated as Pathogens

Purpose of Review

This article presents a comprehensive narrative review of reactive arthritis (ReA) with focus on articles published between 2018 and 2020. We discuss the entire spectrum of microbial agents known to be the main causative agents of ReA, those reported to be rare infective agents, and those reported to be new candidates causing the disease. The discussion is set within the context of changing disease terminology, definition, and classification over time. Further, we include reports that present at least a hint of effective antimicrobial therapy for ReA as documented in case reports or in double-blind controlled studies. Additional information is included on microbial products detected in the joint, as well as on the positivity of HLA-B27.

Recent Findings

Recent reports of ReA cover several rare causative microorganism such as Neisseria meningitides, Clostridium difficile, Escherichia coli, Hafnia alvei, Blastocytosis, Giardia lamblia, Cryptosporidium, Cyclospora cayetanensis, Entamoeba histolytica/dispar, Strongyloides stercoralis, β-haemolytic Streptococci, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Mycobacterium bovis bacillus Calmette-Guerin, and Rickettsia rickettsii. The most prominent new infectious agents implicated as causative in ReA are Staphylococcus lugdunensis, placenta- and umbilical cord–derived Wharton’s jelly, Rothia mucilaginosa, and most importantly the SARS-CoV-2 virus.

Summary

In view of the increasingly large spectrum of causative agents, diagnostic consideration for the disease must include the entire panel of post-infectious arthritides termed ReA. Diagnostic procedures cannot be restricted to the well-known HLA-B27-associated group of ReA, but must also cover the large number of rare forms of arthritis following infections and vaccinations, as well as those elicited by the newly identified members of the ReA group summarized herein. Inclusion of these newly identified etiologic agents must necessitate increased research into the pathogenic mechanisms variously involved, which will engender important insights for treatment and management of ReA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11926-021-01018-6.

Oxidative Stress and Inflammation in SARS-CoV-2- and Chlamydia pneumoniae-Associated Cardiovascular Diseases

Throughout the years, a growing number of studies have provided evidence that oxidative stress and inflammation may be involved in the pathogenesis of infectious agent-related cardiovascular diseases. Amongst the numerous respiratory pathogens, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus responsible for the global ongoing pandemic, and Chlamydia pneumoniae, a widely known intracellular obligate bacteria, seem to have an essential role in promoting reactive oxygen species and cytokine production. The present review highlights the common oxidative and inflammatory molecular pathways underlying the cardiovascular diseases associated with SARS-CoV-2 or C. pneumoniae infections. The main therapeutic and preventive approaches using natural antioxidant compounds will be also discussed.

Treatment of reactive arthritis with biological agents: a review

The pathogenesis of reactive arthritis (ReA) has not been fully elucidated. In recent years, many researchers have confirmed that multiple cytokines are involved in the occurrence and development of ReA. Although ReA is self-limiting, it is still incurable for some patients who have no or a weak response to traditional drugs, such as non-steroidal anti-inflammatory agents, glucocorticoids and immunosuppressive agents. This is called refractory reactive arthritis. Currently, there is insufficient evidences for the treatment of refractory ReA with biological agents, though biological agents against cytokines have been developed over the past few years. This review summarizes the current development of clinical treatments of ReA with biological agents, which provides future investigations on refractory ReA with more evidence and references.

Effects of Immunomodulatory Drug Fingolimod (FTY720) on Chlamydia Dissemination and Pathogenesis

Fingolimod (FTY720), an FDA-approved immunomodulatory drug for treating multiple sclerosis, is an agonist of sphingosine-1-phosphate receptor (S1PR), which has been used as a research tool for inhibiting immune cell trafficking. FTY720 was recently reported to inhibit Chlamydia dissemination. Since genital Chlamydia spreading to the gastrointestinal tract correlated with its pathogenicity in the upper genital tract, we evaluated the effect of FTY720 on chlamydial pathogenicity in the current study. Following an intravaginal inoculation, live chlamydial organisms were detected in mouse rectal swabs. FTY720 treatment significantly delayed live organism shedding in the rectal swabs. However, FTY720 failed to block chlamydial spreading to the gastrointestinal tract. The live chlamydial organisms recovered from rectal swabs reached similar levels between mice with or without FTY720 treatment by day 42 in C57BL/6J and day 28 in CBA/J mice, respectively. Thus, genital Chlamydia is able to launch a 2nd wave of spreading via an FTY720-resistant pathway after the 1st wave of spreading is inhibited by FTY720. As a result, all mice developed significant hydrosalpinx. The FTY720-resistant spreading led to stable colonization of chlamydial organisms in the colon. Consistently, FTY720 did not alter the colonization of intracolonically inoculated Chlamydia Thus, we have demonstrated that, following a delay in chlamydial spreading caused by FTY720, genital Chlamydia is able to both spread to the gastrointestinal tract via an FTY720-resistant pathway and maintain its pathogenicity in the upper genital tract. Further characterization of the FTY720-resistant pathway(s) explored by Chlamydia for spreading to the gastrointestinal tract may promote our understanding of Chlamydia pathogenic mechanisms.

Gastrointestinal Coinfection Promotes Chlamydial Pathogenicity in the Genital Tract

Sexually transmitted Chlamydia, which can cause fibrotic pathology in women's genital tracts, is also frequently detected in the gastrointestinal tract. However, the medical significance of the gastrointestinal Chlamydia remains unclear. A murine Chlamydia readily spreads from the mouse genital tract to the gastrointestinal tract while inducing oviduct fibrotic blockage or hydrosalpinx. We previously proposed a two-hit model in which the mouse gastrointestinal Chlamydia might induce the second hit to promote genital tract pathology, and we are now providing experimental evidence for testing the hypothesis. First, chlamydial mutants that are attenuated in inducing hydrosalpinx in the genital tract also reduce their colonization in the gastrointestinal tract, leading to a better correlation of chlamydial induction of hydrosalpinx with chlamydial colonization in the gastrointestinal tract than in the genital tract. Second, intragastric coinoculation with a wild-type Chlamydia rescued an attenuated Chlamydia mutant to induce hydrosalpinx, while the chlamydial mutant infection in the genital tract alone was unable to induce any significant hydrosalpinx. Finally, the coinoculated gastrointestinal Chlamydia failed to directly spread to the genital tract lumen, suggesting that gastrointestinal Chlamydia may promote genital pathology via an indirect mechanism. Thus, we have demonstrated a significant role of gastrointestinal Chlamydia in promoting pathology in the genital tract possibly via an indirect mechanism. This study provides a novel direction/dimension for further investigating chlamydial pathogenic mechanisms.

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.

Chlamydia-Induced Reactive Arthritis: Disappearing Entity or Lack of Research?

PURPOSE OF REVIEW

Recent studies regarding the frequency of Chlamydia-induced reactive arthritis (ReA) are reviewed, with a focus on the question of whether the entity is in fact disappearing or whether it is simply being underdiagnosed/underreported. Epidemiological reports indicate diversity in the frequency of Chlamydia-associated ReA in various parts of the world, with evidence of declining incidence in some regions.

RECENT FINDINGS

The hypothesis that early effective treatment with antibiotics prevents the manifestation of Chlamydia-associated ReA requires further investigation. For clinicians, it is important to remember that ReA secondary to Lymphogranuloma venereum (LGV) serovars L1-L3 of C. trachomatis is probably underestimated due to a limited awareness of this condition, the re-emergence in Western countries of LGV overall, and the present increasingly rare classical inguinal presentation.

Infectious versus non-infectious causes of oligoarticular inflammatory arthritis: A prospective study from a tertiary care hospital in north India

Oligoarticular arthritis (inflammation of upto 4 joints) has a wide range of infectious and non-infectious etiologies. The aim of our study was to identify the features which could help in the differentiation of infectious from non-infectious arthritis. The study was prospective and observational, and included 100 patients with oligoarticular inflammatory arthritis. The final diagnosis was made using standard diagnostic criteria and the patients were categorized into infectious and non-infectious groups. Among the 100 patients who were recruited, the following final diagnosis were made: peripheral spondyloarthritis (n = 37), axial spondyloarthritis (n = 11), tuberculosis (n = 19), brucellosis (n = 6), septic arthritis (n = 6), gouty arthritis (n = 5), early rheumatoid arthritis (n = 5), non-tubercular mycobacteria (n = 2), SLE (n = 2), post-chikungunya arthritis (n = 2), acute lymphocytic leukaemia (n = 1), pachydermoperiostosis (n = 1), sarcoidosis (n = 1) and juvenile idiopathoic arthritis (n = 1). The patients were categorized into two groups: infectious (33) and non-infectious (60). The presence of monoarthritis, clinically-significant weight loss, hepatomegaly, splenomegaly and erosive arthritis were significantly more common in the infectious group as compared to the non-infectious group.

Chlamydia trachomatis and Chlamydia pneumoniae Interaction with the Host: Latest Advances and Future Prospective

Research in Chlamydia trachomatis and Chlamydia pneumoniae has gained new traction due to recent advances in molecular biology, namely the widespread use of the metagenomic analysis and the development of a stable genomic transformation system, resulting in a better understanding of Chlamydia pathogenesis. C. trachomatis, the leading cause of bacterial sexually transmitted diseases, is responsible of cervicitis and urethritis, and C. pneumoniae, a widespread respiratory pathogen, has long been associated with several chronic inflammatory diseases with great impact on public health. The present review summarizes the current evidence regarding the complex interplay between C. trachomatis and host defense factors in the genital micro-environment as well as the key findings in chronic inflammatory diseases associated to C. pneumoniae.

Interactions of antisera to different Chlamydia and Chlamydophila species with the ribosomal protein RPS27a correlate with impaired protein synthesis in a human choroid plexus papilloma cell line

Chlamydia trachomatis (CT) and the Chlamydophila species (CS) Chlamydophila pneumoniae (CPn), and Chlamydophila psittaci (CPs) are suggested to induce autoantibodies causative of several human autoimmune disorders like rheumatoid arthritis and systemic lupus erythematosus (SLE). The aim of the present study was therefore to identify cellular protein interaction partners with antisera to CT (α-CT) or CS (α-CS) and to identify functional consequences of such interaction in vitro. As detected with a commercial first trimester human prenatal brain multiprotein array (hEXselect, Engine, Germany), the most frequent interaction partner with both α-CT and α-CS was the ribosomal small subunit protein RPS27a. This could be confirmed by Western blot analysis with a recombinant RPS27a sample. In addition, immunocytochemistry with both antisera in the human choroid plexus papilloma cell line HIBCPP revealed a granular cytoplasmic staining, and Western blot analysis with whole-cell protein samples of HIBCPP cells revealed both antisera to label protein bands of different molecular weights and intensity. By 2D Western blot analysis and mass spectrometry, one of the protein spots interacting with α-CT could be identified as the RPS27a. Finally, two different methods for the detection of protein synthesis activity, the SUnSET technique and an HPG fluorescence assay revealed both antisera to cause reduced translational activity in HIBCPP cells. Together with previous findings of RPS27a as an autoimmune target in a mouse model of systemic lupus erythematosus (SLE), these results suggest that infections with CT and/or CS could induce SLE-associated immune modifications. However, direct evidence for a pathogenic role of these interactions for SLE demands further investigations.

Chlamydiales, Anaplasma and Bartonella: persistence and immune escape of intracellular bacteria

Intracellular bacteria, such as Chlamydiales, Anaplasma or Bartonella, need to persist inside their host in order to complete their developmental cycle and to infect new hosts. In order to escape from the host immune system, intracellular bacteria have developed diverse mechanisms of persistence, which can directly impact the health of their host.

Potential risk factors for reactive arthritis and persistence of symptoms at 2 years: a case-control study with longitudinal follow-up

The objective of the study is to determine the risk factors for the development of reactive arthritis (ReA) and examine the factors associated with the persistence of symptoms. Patients with a new diagnosis of ReA and controls with a gastrointestinal (GI), urogenital, or sexually transmitted infection in the 3-6 months prior to study entry were prospectively enrolled in Guatemala City. ReA patients fulfilled the Assessment in Spondyloarthritis International Society criteria for peripheral spondyloarthropathy (SpA). Patients underwent history, examination, Achilles tendon ultrasound, and blood draw. Human leukocyte antigen (HLA) type and serum biomarkers were measured. t tests and nonparametric equivalents were used to examine the association of clinical, laboratory, and imaging factors with ReA. Patients were contacted 2 years later to assess for persistence of symptoms. Study subjects included patients with ReA (N = 32) and controls (N = 32). ReA patients were most frequently infected in April whereas controls were most frequently infected in August. Two ReA patients and two controls were HLA-B27-positive. Serum cathepsin K and C-reactive protein were higher in ReA patients compared to controls (p = 0.03 for both), while total cholesterol and low-density lipoprotein were lower (p = 0.008 and 0.045, respectively). Among those with ReA, 15 (47%) patients had continued symptoms at 2 years. These patients had a lower matrix metalloproteinase-3 level at diagnosis than patients for whom ReA resolved (p = 0.004). HLA-B27 was not associated with development of ReA in Guatemala; however, the month of infection was associated with ReA. The most striking finding was the persistence of arthritis at 2 years in nearly half of the patients.

Reactive Arthritis

Reactive arthritis is classified as a spondyloarthropathy. Current concepts of disease suggest an infectious trigger, followed by inflammatory arthritis. Several mechanisms have been proposed to explain the interaction of host susceptibility and microorganism. Diagnosis relies on a compatible clinical syndrome and microbiologic confirmation of the pathogen. Antibiotic therapy seems useful in Chlamydia-triggered arthritis. The role of antibiotics in arthritis triggered by enteric pathogens is less clear. The role of tumor necrosis factor alpha inhibitors in therapy is evolving. Many patients have a course limited to a few months, but others experience extraarticular disease and more prolonged courses.