Disease mechanisms in reactive arthritis

Immunologic derangement caused by intestinal dysbiosis and stress is the intrinsic basis of reactive arthritis

Reactive arthritis (ReA) is defined as arthritis resulting from infections in other body parts, such as the gastrointestinal and urogenital tracts. The primary clinical manifestations involve acute-onset and self-limiting asymmetric large joint inflammation in the lower limbs. Although bacterial or chlamydia infections have long been recognized as playing a pivotal role in its pathogenesis, recent studies suggest that antibiotic treatment may perpetuate rather than eradicate chlamydia within the host, indicating an involvement of other mechanisms in Reactive arthritis. Reactive arthritis is currently believed to be associated with infection, genetic marker (HLA-B27), and immunologic derangement. As an autoimmune disease, increasing attention has been given to understanding the role of the immune system in Reactive arthritis. This review focuses on elucidating how the immune system mediates reactive arthritis and explores the roles of intestinal dysbiosis-induced immune disorders and stress-related factors in autoimmune diseases, providing novel insights into understanding reactive arthritis.

Reactive Arthritis Post-SARS-CoV-2

Reactive arthritis (ReA) following bacterial infection from the urogenital and gastrointestinal tract is widely described but is not typical post-viral infections. This report presents the second case of ReA after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States. A 45-year-old black male with chronic low back pain was hospitalized for 45 days with coronavirus disease 2019 (COVID-19), complicated due to the development of multiorgan failure managed with intubation, extracorporeal membrane oxygenation, and hemodialysis. He was subsequently discharged to an acute rehabilitation facility where he complained of new-onset pain in his shoulders, left elbow, and left knee three weeks after a negative SARS-CoV-2 test. He was readmitted from his acute rehabilitation facility due to recurrent fever and the development of a swollen, warm left knee. Laboratory studies at readmission showed elevated inflammatory markers, negative extensive infectious disease workup, and aseptic inflammatory left knee synovial fluid without crystals. Testing returned negative for most common antibodies seen in immune-mediated arthritides (e.g., rheumatoid arthritis, systemic lupus erythematosus), as well as for common respiratory and gastrointestinal tract pathogens responsible for viral arthritis. The multidisciplinary inpatient medical team deemed the clinical presentation and laboratory findings most consistent with ReA. The patient received a course of oral corticosteroids, followed by a second course due to the recurrence of symptoms weeks after initial treatment and recovery. The current body of medical literature on SARS-CoV-2 pathophysiology supports plausible mechanisms on how this infection may induce ReA. Such a scenario should be considered in the differential of COVID-19-recovered patients presenting with polyarthritis as prompt steroid treatment may help patient recovery.

Reactive arthritis: a clinical review

Reactive arthritis (ReA) is a form of inflammatory arthritis triggered by a remote antecedent infection, usually in the genitourinary or gastrointestinal tract. It is part of the spondyloarthropathy (SpA) spectrum, an umbrella term for a group of distinct conditions with shared clinical features. Typically, it presents with an asymmetric oligoarthritis of the lower limb joints, and patients may also have sacroiliitis, enthesitis and dactylitis. Other features often seen include anterior uveitis, urethritis and skin manifestations such as pustular lesions on the plantar areas. Although ReA was characterised initially as a sterile arthritis, the detection of metabolically active Chlamydia species in the joint fluid of some affected patients has generated further questions on the pathophysiology of this condition. There are no formal diagnostic criteria, and the diagnosis is mainly clinical. HLA-B27 can support the diagnosis in the correct clinical context, and serves as a prognostic indicator. The majority of patients have a self-limiting course, but some develop chronic SpA and require immunomodulatory therapy.

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.

Reactive Arthritis: Update

Purpose of Review

The aim of this paper is to provide an overview about reactive arthritis, with an update regarding pathophysiology and therapeutic approach of the disease, outlining the clinical features and diagnostic approach, based on recent literature review.

Recent Findings

Reactive arthritis is considered to be part of the spectrum of the spondyloarthritis. Its epidemiology is changing worldwide due to several reasons, among them are as follows: different diagnosis approach and clinical presentations, different grades of infection, microbiome changes, etc. The understanding of pathophysiological models is challenging, but recent studies contribute to elucidate the major factors involved in the development of the disease. The management of ReA depends on the triggering agent and the phase of disease, whether it is acute or chronic.

Summary

The association between the microbiome changes and spondyloarthropathies (ReA) is becoming increasingly evident. The results regarding the biologic treatment on refectory ReA are promising.

Microbes, helminths, and rheumatic diseases

There has been a progressive interest on modifications of the human defense system following insults occurring in the interface between our body and the external environment, as they may provoke or worsen disease states. Studies suggest that billions of germs, which compose the gut microbiota influence one's innate and adaptive immune responses at the intestinal level, but these microorganisms may also impact rheumatic diseases. The microbiota of the skin, respiratory, and urinary tracts may also be relevant in rheumatology. Evidence indicates that changes in the gut microbiome alter the pathogenesis of immune-mediated diseases such as rheumatoid arthritis and ankylosing spondylitis but also of other disorders like atherosclerosis and osteoarthritis. Therapeutic strategies to modify the microbiota, including probiotics and fecal microbiota transplantation, have been received with skepticism, which, in turn, has drawn attention back to previously developed interventions such as antibiotics. Helminths adapted to humans over the evolution process, but their role in disease modulation, particularly immune-mediated diseases, remains to be understood. The present review focuses on data concerning modifications of the immune system induced by interactions with microbes and pluricellular organisms, namely helminths, and their impact on rheumatic diseases. Practical aspects, including specific microbiota-targeted therapies, are also discussed.

NMR-Based Serum Metabolomics Revealed Distinctive Metabolic Patterns in Reactive Arthritis Compared with Rheumatoid Arthritis

Reactive arthritis (ReA) is a member of seronegative spondyloarthropathy (SSA), which involves an acute/subacute onset of asymmetrical lower limb joint inflammation weeks after a genitourinary/gastrointestinal infection. The diagnosis is clinical because it is difficult to culture the microbes from synovial fluid. Arthritis patients with a similar clinical picture but lapsed history of an immediate preceding infection that do not fulfill the diagnostic criteria of other members of SSA, such as ankylosing spondylitis, psoriatic arthritis, and arthritis associated with inflammatory bowel disease, are labeled as peripheral undifferentiated spondyloarthropathy (uSpA). Both ReA and uSpA patients show a strong association with class I major histocompatibility complex allele, HLA-B27, and a clear association with an infectious trigger; however, the disease mechanism is far from clear. Because the clinical picture is largely dominated by rheumatoid-arthritis (RA)-like features including elevated levels of inflammatory markers (such as ESR, CRP, etc.), these overlapping symptoms often confound the clinical diagnosis and represent a clinical dilemma, making treatment choice more generalized. Therefore, there is a compelling need to identify biomarkers that can support the diagnosis of ReA/uSpA. In the present study, we performed NMR-based serum metabolomics analysis and demonstrated that ReA/uSpA patients are clearly distinguishable from controls and further that these patients can also be distinguished from the RA patients based on the metabolic profiles, with high sensitivity and specificity. The discriminatory metabolites were further subjected to area under receiver operating characteristic curve analysis, which led to the identification of four metabolic entities (i.e., valine, leucine, arginine/lysine, and phenylalanine) that could differentiate ReA/uSpA from RA.

Yersinia enterocolitica biotype 1A: a possible new trigger of reactive arthritis

Yersinia enterocolitica (YE) biotype 1A is generally considered non-pathogenic, and the role of it in causing reactive musculoskeletal complications is unclear. We evaluated the capability of YE biotype 1A to induce reactive arthritis (ReA) and other reactive musculoskeletal symptoms. Analysis of self-reported musculoskeletal symptoms was supplemented with a telephone interview (with a permission to acquire copies of patient files from a local physician or hospital) and/or clinical examination of subjects with recent musculoskeletal symptoms after a positive stool culture for YE. The diagnoses of ReA and reactive tendinitis and enthesitis (ReTe) were defined as "definite" when based on clinical examination and/or on interview by phone and "probable" when based solely on the questionnaire. Of 120 subjects, who reported musculoskeletal symptoms, 100 were included in the final analysis. Among these 100 patients, 68% had YE biotype 1A, 16% YE bio/serotype 4, and 1% biotype 2 infection; the remaining 15% had different YE-like strains or a non-biotypable strain. Of the 21 patients with ReA and of the 14 patients with ReTe, the diagnosis was definite in 9 and 7 patients and probable in 12 and 7 patients, respectively. The clinical picture of ReA caused by YE biotype 1A was similar with other bio/serotypes of YE. The definite ReA due to YE biotype 1A occurred in middle-aged adults (5 men, 4 women) with the most frequently affected joints being the knees and ankles. We suggest that YE biotype 1A should be taken into account as a new trigger of ReA.

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.

Salmonella as an Inducer of Autoimmunity

A clear etiological link has been established between infection with several gram-negative enteric pathogens, including Salmonella spp., and the incidence of reactive arthritis (ReA), an autoimmune disease that largely affects the joints. ReA is sometimes referred to as Reiter's syndrome, particularly when accompanied by uveitis and urethritis. This review reviews the evidence etiologically linking Salmonella infection with autoimmune disease and addresses the roles that bacterial and host elements play in controlling disease outcome. ReA is an autoimmune disease that largely consists of painful joint inflammation but also can include inflammation of the eye, gastrointestinal tract, and skin. ReA is a member of a broad spectrum of chronic inflammatory disorders termed the seronegative spondyloarthropathies (SNSpAs) that includes ankylosing spondylitis (AS), psoriatic arthritis, and enteropathic arthritis. Salmonella species, as well as other enteric pathogens associated with postgastroenteritis ReA, are facultative intracellular gram-negative bacteria. Many studies have analyzed the association of the HLA class I molecule, HLA-B27, with SNSpAs. Whereas B27 has been shown to be present in 90 to 95% of cases of AS, the association of the B27 haplotype with other SNSpAs is more tenuous. The clear association between ReA and infection with Salmonella or other gram-negative enteric pathogens has led to the suggestion that the adaptive immune response to infection has an autoimmune component. In addition to various Salmonella species, other gram-negative enteric pathogens have been linked to the development of ReA. Given their close relationship to Salmonella, this review considers the involvement of Shigella species in ReA.

Developmental plasticity of murine and human Foxp3(+) regulatory T cells

Murine and human CD4(+) regulatory T (Treg) cells expressing the Forkhead box p3 (Foxp3) transcription factor represent a distinct, highly differentiated CD4(+) T cell lineage that is programmed for dominant self-tolerance and control of immune responses against a variety of foreign antigens. Sustained Foxp3 expression in these cells drives the differentiation of a regulatory phenotype and ensures the stability of their suppressive functions under a variety of inflammatory settings. Some recent studies have challenged this premise and advanced the notion that Foxp3(+) Treg cells manifest a high degree of functional plasticity that enables them to adapt and reprogram into effector-like T cells in response to various inflammatory stimuli. The concept of Treg cell plasticity remains highly contentious, with a high degree of variation in measured plasticity potential observed under different experimental conditions. In this chapter, we propose a unifying model of Treg cell plasticity, which hypothesizes that the stable fates of regulatory and effector T (Teff) cell lineages allow transient plasticity into the alternative lineage under a discrete set of microenvironmental influences associated with, respectively, the initiation and resolution phases of infection. This model utilizes a theoretical framework consistent with the requirements for effective immune regulation and accounts for both the extraordinary long-term stability of Treg cells and the observed fate plasticity.

Circulating soluble interleukin‐2 receptor level predicts remission in very early reactive arthritis

OBJECTIVES

To assess the predictive value of serum soluble interleukin-2 receptor (sIL-2R) levels in patients with acute reactive arthritis (ReA).

METHODS

The study includes 26 patients with acute ReA who had participated in a prospective population-based cohort study of very early arthritis. The patients had had arthritis of at least one joint with a maximum duration of 3 months. They were assessed by a rheumatologist on presentation and 6 months later. Serum sIL-2R levels on presentation were measured by the Immulite automated immunoassay analyser. Remission at 6 months, defined by the absence of swollen and tender joints, was related to the baseline sIL-2R level using a permutation test with general scores. Bootstrap estimation was used to derive the 95% confidence interval (CI).

RESULTS

A total of 17 patients (65%) were in remission at 6 months and nine patients (35%) still had joint symptoms. In patients reaching remission within 6 months, the mean baseline sIL-2R level, 891 U/mL (95% CI: 658 to 1123), was higher than in patients not reaching remission, 501 U/mL (95% CI: 436 to 566), p = 0.022.

CONCLUSIONS

A high serum sIL-2R level at baseline is a predictor of remission in patients with acute ReA.

Association of various inflammatory diseases with human leukocyte antigens B27, B7, Bw4 and Bw6 in patients with SSA

Seronegative spondyloarthropathies (SSA) are a group of inflammatory disorders, which clinically involve the axial skeleton and the sacroiliiac and shoulder joints. The aim of the present study was to study the association of HLA B27, B7, Bw4 and Bw6 with some inflammatory diseases, in SSA patients in our area. A total of 220 SSA patients were studied and HLA typing for these antigens were done by the complement-mediated microcytotoxicity method. The total positivity of B27 was found to be 68.64% in SSA patients. Tubercular infection (chi(2) = 8.06) and acute anterior uveitis (chi(2) = 6.19) were found to be statistically significant (P < 0.05) in B27-positive SSA patients. Tuberculosis was also found to be significantly (chi(2) = 6.40) associated with Bw4. In SSA urinary tract infection, gastrointestinal infection and streptococcal infection were not significantly associated with B27, B7, Bw4 or Bw6 antigens. Our study concludes that microbial infections do have some pathogenic role in causing SSA.

A review of pediatric uveitis: part II. Autoimmune diseases and treatment modalities

Uveitis is a manifestation of complex processes that can represent an infectious process or a dysfunction of the immune system that may have grave effects on the eye. Although infectious causes, once properly identified, may be successfully treated by addressing the inciting organism with recognized interventions, the immune-modulated chronic forms of uveitis often provide more complex challenges in management. Recent strides in understanding the inflammatory pathway and better bioengineering capabilities have resulted in some new modalities of treatment.

A Mariner with Crippling Arthritis and Bleeding Eyes

A 41-year-old mariner developed acute arthritis affecting his legs more than his arms or hands during a violent storm on his return from the first of four voyages of discovery. He experienced repeated attacks of the arthritis over the ensuing 14 years, which on at least two occasions were accompanied by painful eyes "much affected with bleeding." He died shortly before his 55 birthday "quite paralyzed and bedridden." Who was he, and what was the likely etiology of his disorder?

Infection and work stress are potential triggers of ankylosing spondylitis

The objective of the study was to investigate potential triggering events for the onset of ankylosing spondylitis (AS). A large retrospective population survey of 1,080 AS patients was carried out by multi-faceted questionnaire. A nested case-control study compared the cohort to 102 patients with lumbar disc prolapse. Participants with AS had a mean age of 49.8 years, mean age of disease onset was 25.2 years and 63% of the cohort were male. Seventy-nine per cent knew they were human leucocyte antigen (HLA)-B27-positive, and a further 12.5% were unaware of their HLA-B27 status. Infections were relatively common in the 3 months leading to the first symptoms, 4.6% reporting gastrointestinal infection, 2.5% reporting urinary tract infection and 2.6% respiratory infection. Five per cent reported heavy physical activity in the 3 months prior to the onset of symptoms, 4.2% emotional stressors and 3.1% work stressors. Injury and surgery were less commonly reported (1.7 and 0.7%, respectively). Pregnancy was reported by 7.4% of the female participants. When the 12 months leading up to the first symptoms was compared to the 12 months previous to that, work stressors (OR 1.5), and pregnancy (OR 2.5) infection (OR 1.5 to 1.8) were significantly more common closer to disease onset. Infection and work stressors are potential triggers for the onset of AS; however, low rates suggest they are only a small part of the environmental milieu that combines with a genetic predisposition to cause the development of this chronic inflammatory disease.

Newer Therapeutic Approaches: Spondyloarthritis and Uveitis

Over the last 5 years considerable progress has taken place in the therapeutic approach to spondyloarthritis (SpA). This progress is due in large part to the development of effective biologic therapies and to improved clinical trial design and implementation. This article summarizes treatment advances in SpA with emphasis on the efficacy and safety of biologic agents in the treatment of psoriatic arthritis, ankylosing spondylitis, undifferentiated spondyloarthropathy, and uveitis.

Treatment update on spondyloarthropathy

PURPOSE OF REVIEW

The unexpected success of the tumor necrosis factor antagonists in ankylosing spondylitis and psoriatic arthritis has generated considerable enthusiasm regarding the therapeutic potential of these drugs. By contrast, concerns regarding the high cost and long-term safety of the tumor necrosis factor blocking agents have prompted investigators to take a closer look at more traditional anti-inflammatory agents and to explore novel therapeutic targets. The purpose of this review is to summarize treatment advances in spondylarthropathy over the past year and to discuss potential future therapies.

RECENT FINDINGS

Recent studies indicate that the morbidity of ankylosing spondylitis and PsA are considerably higher than previously reported. Etanercept, infliximab and adalimumab safely and effectively relieved the signs and symptoms of psoriatic arthritis patients in phase III trials. Etanercept and infliximab were also effective in phase III trials in ankylosing spondylitis. Etanercept slowed radiographic progression in psoriatic arthritis trials, but it is not known whether tumor necrosis factor antagonists can prevent structural damage in ankylosing spondylitis. One trial showed that methotrexate may be effective for relieving the pain of axial disease in ankylosing spondylitis but these findings contradict two previous studies. For reactive arthritis and undifferentiated spondylarthropathy, a combination of antibiotics may be more effective than a single antibiotic for the relief of musculoskeletal symptoms. Last, potential therapeutic targets include interleukin-1, interleukin-12, B lymphocytes, accessory molecules on T lymphocytes, and angiogenic factors.

SUMMARY

Phase III trials have confirmed that tumor necrosis factor antagonists are effective and safe for the treatment of ankylosing spondylitis and psoriatic arthritis. For patients who do not respond to tumor necrosis factor blockade, several treatment options are under study. Information from these trials will more clearly define the role of disease-modifying antirheumatic drugs, novel therapeutic agents, and antibiotics in the treatment of spondylarthropathy.