Patients with rheumatic disorders have an increased risk of cardiovascular disease (CVD). This excess co-morbidity is not fully explained by traditional risk factors. Disease severity is a major risk factor for CVD in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Shared disease mechanisms in atherosclerosis and rheumatic disorders include immune dysregulation and inflammatory pathways, which are potential targets for therapy. Lessons from RA and SLE may have implications for future research on the pathogenesis of atherosclerotic vascular disease in general. Recent data indicate that suppression of inflammation reduces the risk of CVD morbidity and mortality in patients with severe RA. The modest, but clinically relevant, efficacy of atorvastatin treatment in RA adds to the evidence for important anti-inflammatory properties for statins. There is increased recognition of the need for structured preventive strategies to reduce the risk of CVD in patients with rheumatic disease. Such strategies should be based on insights into the role of inflammation in CVD, as well as optimal management of life style related risk factors. In this review, the research agenda for understanding and preventing CVD co-morbidity in patients with rheumatic disorders is discussed.
rheumatoid arthritis; systemic lupus erythematosus; cardiovascular disease; inflammation
Despite identifying that rheumatic fever (RF) is the result of an immunological reaction following group-A beta-hemolytic streptococcal infection, the pathogenesis remains elusive. RF has been incorrectly designated as causing pancarditis, since it does not cause myocarditis. Research directed toward myocarditis, targeting myosin to unravel the pathogenesis has not succeeded in more than 60 years. RF causes permanent damage to cardiac valves. The mitral valve (MV), derived from the wall of the left ventricle, is composed of a central core of connective tissue, covered on both sides by endothelium. The left ventricle does not have either myocardial or intermyocardial connective tissue involvement in RF. By exclusion, therefore, the primary site of RF damage appears to be the endothelium. Evaluation of the histopathology and immunopathology indicates that RF is a disease of the valvular and vascular endothelium. It is not a connective tissue disorder. Research to identify pathogenesis needs to be focused toward valvular endothelium.
Endothelium; pathogenesis; poststreptococcal; acute glomerulonephritis; myocarditis; myosin; rheumatic fever
Since 2003, the tropical arthritogenic chikungunya (CHIK) virus has become an increasingly medical and economic burden in affected areas as it can often result in long-term disabilities. The clinical spectrum of post-CHIK (pCHIK) rheumatic disorders is wide. Evidence-based recommendations are needed to help physicians manage the treatment of afflicted patients.
Patients and methods
We conducted a 6-year case series retrospective study in Reunion Island of patients referred to a rheumatologist due to continuous rheumatic or musculoskeletal pains that persisted following CHIK infection. These various disorders were documented in terms of their clinical and therapeutic courses. Post-CHIK de novo chronic inflammatory rheumatisms (CIRs) were identified according to validated criteria.
We reviewed 159 patient medical files. Ninety-four patients (59%) who were free of any articular disorder prior to CHIK met the CIR criteria: rheumatoid arthritis (n=40), spondyloarthritis (n=33), undifferentiated polyarthritis (n=21). Bone lesions detectable by radiography occurred in half of the patients (median time: 3.5 years pCHIK). A positive therapeutic response was achieved in 54 out of the 72 patients (75%) who were treated with methotrexate (MTX). Twelve out of the 92 patients (13%) received immunomodulatory biologic agents due to failure of contra-indication of MTX treatment. Other patients mainly presented with mechanical shoulder or knee disorders, bilateral distal polyarthralgia that was frequently associated with oedema at the extremities and tunnel syndromes. These pCHIK musculoskeletal disorders (MSDs) were managed with pain-killers, local and/or general anti-inflammatory drugs, and physiotherapy.
Rheumatologists in Reunion Island managed CHIK rheumatic disorders in a pragmatic manner following the outbreak in 2006. This retrospective study describes the common mechanical and inflammatory pCHIK disorders. We provide a diagnostic and therapeutic algorithm to help physicians deal with chronic patients, and to limit both functional and economic impacts. The therapeutic indication of MTX in pCHIK CIR could be approved in future efficacy trials.
With a 6-year insight, we extensively and retrospectively describe clinical profiles and specific treatments of mechanical and inflammatory post-chikungunya rheumatic disorders. In the current context of chikungunya’s global spread, we provide the first diagnostic and therapeutic algorithm to guide physicians according to the amount of time that has elapsed since the acute CHIK infection.
Patients with rheumatic diseases have an increased risk of mortality by cardiovascular events. In fact, several rheumatic diseases such as rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, and ankylosing spondylitis are associated with a higher prevalence of cardiovascular diseases (CVDs). Although traditional cardiovascular risk factors have been involved in the pathogenesis of cardiovascular diseases in rheumatic patients, these alterations do not completely explain the enhanced cardiovascular risk in this population. Obesity and its pathologic alteration of fat mass and dysfunction, due to an altered pattern of secretion of proinflammatory adipokines, could be one of the links between cardiovascular and rheumatic diseases. Indeed, the incidence of CVDs is augmented in obese individuals with rheumatic disorders. Thus, in this paper we explore in detail the relationships among adipokines, rheumatic diseases, and cardiovascular complications by giving to the reader a holistic vision and several suggestions for future perspectives and potential clinical implications.
MicroRNAs (miRNAs) are endogenous, non-coding, single-stranded RNAs about 21 nucleotides in length. miRNAs have been shown to regulate gene expression and thus influence a wide range of physiological and pathological processes. Moreover, they are detected in a variety of sources, including tissues, serum, and other body fluids, such as saliva. The role of miRNAs is evident in various malignant and nonmalignant diseases, and there is accumulating evidence also for an important role of miRNAs in systemic rheumatic diseases. Abnormal expression of miRNAs has been reported in autoimmune diseases, mainly in systemic lupus erythematosus and rheumatoid arthritis. miRNAs can be aberrantly expressed even in the different stages of disease progression, allowing miRNAs to be important biomarkers, to help understand the pathogenesis of the disease, and to monitor disease activity and effects of treatment. Different groups have demonstrated a link between miRNA expression and disease activity, as in the case of renal flares in lupus patients. Moreover, miRNAs are emerging as potential targets for new therapeutic strategies of autoimmune disorders. Taken together, recent data demonstrate that miRNAs can influence mechanisms involved in the pathogenesis, relapse, and specific organ involvement of autoimmune diseases. The ultimate goal is the identification of a miRNA target or targets that could be manipulated through specific therapies, aiming at activation or inhibition of specific miRNAs responsible for the development of disease.
Rheumatic fever (RF) and rheumatic heart disease (RHD) continue to be a major health hazard in most developing countries as well as sporadically in developed economies. Despite reservations about the utility, echocardiographic and Doppler (E&D) studies have identified a massive burden of RHD suggesting the inadequacy of the Jones’ criteria updated by the American Heart Association in 1992. Subclinical carditis has been recognized by E&D in patients with acute RF without clinical carditis as well as by follow up of RHD patients presenting as isolated chorea or those without clinical evidence of carditis. Over the years, the medical management of RF has not changed. Paediatric and juvenile mitral stenosis (MS), upto the age of 12 and 20 yr respectively, severe enough to require operative treatement was documented. These negate the belief that patients of RHD become symptomatic ≥20 years after RF as well as the fact that congestive cardiac failure in childhood indicates active carditis and RF. Non-surgical balloon mitral valvotomy for MS has been initiated. Mitral and/or aortic valve replacement during active RF in patients not responding to medical treatment has been found to be life saving as well as confirming that congestive heart failure in acute RF is due to an acute haemodynamic overload. Pathogenesis as well as susceptibility to RF continue to be elusive. Prevention of RF morbidity depends on secondary prophylaxis which cannot reduce the burden of diseases. Primary prophylaxis is not feasible in the absence of a suitable vaccine. Attempts to design an antistreptococcal vaccine utilizing the M-protein has not succeeded in the last 40 years. Besides pathogenesis many other questions remain unanswered.
Antistreptococcal vaccine; heart disease; myocarditis; rheumatic fever; rheumatic heart disease; streptococcal infections; subclinical carditis
The pattern of rheumatic disease in Africa differs from that in Europe and the United States and these differences may provide clues to its cause or pathogenesis. In a six month prospective analysis of 141 patients (83 female) attending a rheumatic diseases clinic rheumatoid arthritis was the commonest disorder, occurring in 49 patients. Twenty seven of the 49 (55%) were seropositive, 25 (51%) had erosive disease with rheumatoid nodules (13/49, 27%), and extra-articular complications (6/49, 12%), indicating a pattern of disease unlike the early reports from Africa. Systemic lupus erythematosus found in 18/141 (13%), gout in 12 (9%), ankylosing spondylitis in six (4%), and Reiter's syndrome in five (4%), in contrast with their rarity in previous reports from Africa, were not uncommon, whereas tropical polyarthritis was seldom diagnosed. The pattern of rheumatic disease in Harare, a large city, is changing to approximate more closely the pattern seen in developed countries.
The glucocorticoid receptor (GR), a member of the nuclear receptor superfamily, mediates most of the known biologic effects of glucocorticoids. The human GR gene consists of 9 exons and expresses 2 alternative splicing isoforms, the GRα and GRβ. GRα is the classic receptor that binds to glucocorticoids and mediates most of the known actions of glucocorticoids, while GRβ does not bind to these hormones and exerts a dominant negative effect upon the GRα-induced transcriptional activity. Each of the two GR splice isoforms has 8 translational variants with specific transcriptional activity and tissue distribution. GRα consists of three subdomains, translocates from the cytoplasm into the nucleus upon binding to glucocorticoids, and regulates the transcriptional activity of numerous glucocorticoid-responsive genes either by binding to its cognate DNA sequences or by interacting with other transcription factors. In addition to these genomic actions, the GR also exerts rapid, non-genomic effects, which are possibly mediated by membrane-localized receptors or by translocation into the mitochondria. All these actions of the GR appear to play an important role in the regulation of the immune system. Specifically, the splicing variant GRβ may be involved in the pathogenesis of rheumatic diseases, while the circadian regulation of the GR activity via acetylation by the Clock transcription factor may have therapeutic implications for the preferential timing of glucocorticoid administration in autoimmune inflammatory disorders.
The hepatitis C virus (HCV) is both hepatotropic and lymphotropic, responsible for a great number of hepatic and extrahepatic immune-system disorders that comprise the so-called HCV syndrome. HCV-associated rheumatic diseases are characterized by frequent clinico-serological overlap; therefore, correct classification of individual patients is necessary before therapeutic decisions are made. This is particularly difficult to do, however, because of the coexistence of viral infection and complex autoimmune alterations. In this context, mixed cryoglobulinemia syndrome (MCs) represents the prototype of virus-related autoimmune-lymphoproliferative diseases. MCs can be treated at different levels by means of etiological treatment with antivirals (peg-interferon-alpha plus ribavirin) aimed at HCV eradication and/or pathogenetic/symptomatic treatments directed to both immune-system alterations and the vasculitic process (rituximab, cyclophosphamide, steroids, plasmapheresis, and so on). In clinical practice, the therapeutic strategy should be modulated according to severity/activity of the MCs and possibly tailored to each individual patient's conditions. Cryoglobulinemic skin ulcers may represent a therapeutic challenge, which should be managed by means of both local and systemic treatments. HCV-associated arthritis should be differentiated from the simple comorbidity of HCV infection and classical rheumatoid arthritis. It may be treated with low doses of steroids and/or hydroxychloroquine; the use of biologics (rituximab) may be considered in more severe cases. Primary Sjögren's syndrome is rarely associated with HCV infection, while sicca syndrome and myalgia are frequently detectable in hepatitis C patients, with or without cryoglobulinemic vasculitis. Other autoimmune rheumatic disorders (poly/dermatomyositis, polyarteritis nodosa, osteosclerosis, fibromyalgia, and so on) have been reported as potentially associated with HCV infection in patient populations from different countries, suggesting the role of genetic and/or environmental co-factors. The therapeutic approach to these disorders should be decided according to each individual patient's evaluation, including hepatic, virological, and immunological findings.
We now stand at a critical juncture for rheumatic fever (RF) and rheumatic heart disease (RHD) control. In recent years, we have seen a surge of interest in these diseases in regions of the world where RF/RHD mostly occur. This brings real opportunities to make dramatic progress in the next few years, but also real risks if we miss these opportunities. Most public health and clinical approaches in RF/RHD arose directly from programmes of research. Many unanswered questions remain, including those around how to implement what we know will work, so research will continue to be essential in our efforts to bring a global solution to this disease. Here we outline our proposed research priorities in RF/RHD for the coming decade, grouped under the following four challenges: Translating what we know already into practical RHD control; How to identify people with RHD earlier, so that preventive measures have a higher chance of success; Better understanding of disease pathogenesis, with a view to improved diagnosis and treatment of ARF and RHD; and Finding an effective approach to primary prevention. We propose a mixture of basic, applied, and implementation science. With concerted efforts, strong links to clinical and public health infrastructure, and advocacy and funding support from the international community, there are good prospects for controlling these RF and RHD over the next decade.
Rheumatic fever; rheumatic heart disease; prevention
Rheumatic diseases are a diverse group of disorders. Most of these diseases are heterogeneous in nature and show varying responsiveness to treatment. Because our understanding of the molecular complexity of rheumatic diseases is incomplete and criteria for categorization are limited, we mainly refer to them in terms of group averages. The advent of DNA microarray technology has provided a powerful tool to gain insight into the molecular complexity of these diseases; this technology facilitates open-ended survey to identify comprehensively the genes and biological pathways that are associated with clinically defined conditions. During the past decade, encouraging results have been generated in the molecular description of complex rheumatic diseases, such as rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome and systemic sclerosis. Here, we describe developments in genomics research during the past decade that have contributed to our knowledge of pathogenesis, and to the identification of biomarkers for diagnosis, patient stratification and prognostication.
Many rheumatologic disorders, most notably Sjögren's syndrome, are associated with dental complications and in some cases oral diseases may trigger or drive connective tissue disease. During the past three decades the treatment in rheumatology was revolutionized by the introduction of disease-modifying anti-rheumatic drugs. Advances in our understanding of the pathogenesis of rheumatic diseases have led to the discovery of critical mechanisms of inflammation and autoimmunity and the invention of new target-specific biologic agents. In this review, we will summarize the current state of biologic therapies in rheumatology and discuss the implications of these on oral health and disease.
autoimmunity; biologic therapies; monoclonal antibodies; rheumatic diseases; Sjögren's syndrome
Inflammatory joint diseases such as rheumatoid arthritis, as well as other rheumatic conditions, such as systemic lupus erythematosus (SLE) and ankylosing spondylitis, comprise a heterogeneous group of joint disorders that are all associated with extra-articular side effects, including bone loss and fractures. The concept of osteoimmunology is based on growing insights into the links between the immune system and bone. The pathogenesis of osteoporosis in these patients is multifactorial. We have, more or less as an example, described this extensively for patients with SLE. High disease activity (inflammation) and immobility are common factors that substantially increase fracture risk in these patients, on top of the background fracture risk based on, among other factors, age, body mass index, and gender. Although no fracture reduction has been shown in intervention studies in patients with inflammatory rheumatic diseases, we present treatment options that might be useful for clinicians who are treating these patients.
Osteoporosis; Fractures; Rheumatoid arthritis; Systemic lupus erythematosus; SLE; Ankylosing spondylitis; Metabolic bone disease; Inflammation; Bone; Medicine & Public Health; Rheumatology
Immunologic research has clarified many aspects of the pathogenesis of inflammatory rheumatic disorders. Biologic drugs acting on different steps of the immune response, including cytokines, B- and T-cell lymphocytes, have been marketed over the past 10 years for the treatment of rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA). Randomized controlled trials (RCTs) of anti-cytokine agents in RA (including the anti-tumor necrosis factor alpha (TNFα) drugs infliximab, etanercept, adalimumab, golimumab, certolizumab, anti-interleukin (IL)-1 anakinra, and anti-IL-6 tocilizumab) demonstrated a significant efficacy compared to traditional therapies, if combined with methotrexate (MTX), as measured by ACR 20, 50 and 70 response criteria. The new therapies have also been demonstrated to be superior to MTX in slowing or halting articular damage. RCTs have shown the efficacy of anti-TNFα in AS patients through significant improvement of symptoms and function. Trials of anti-TNFα in PsA patients showed marked improvement of articular symptoms for psoriasis and radiological disease progression. More recent studies have demonstrated the efficacy of B-cell depletion with rituximab, and T-cell inactivation with abatacept. All these drugs have a satisfactory safety profile. This paper reviews the different aspects of efficacy and tolerability of biologics in the therapy of RA, AS, and PsA.
anti-TNF; anti-cytokine agents; rituximab; abatacept; rheumatoid arthritis; psoriatic arthritis; ankylosing spondylitis
Rheumatic fever in childhood is the most common cause of Mitral Stenosis in developing countries. The disease is characterized by damaged and deformed mitral valves predisposing them to scarring and narrowing (stenosis) that results in left atrial hypertrophy followed by heart failure. Presently, echocardiography is the main imaging technique used to diagnose Mitral Stenosis. Despite the high prevalence and increased morbidity, no biochemical indicators are available for prediction, diagnosis and management of the disease. Adopting a proteomic approach to study Rheumatic Mitral Stenosis may therefore throw some light in this direction. In our study, we undertook plasma proteomics of human subjects suffering from Rheumatic Mitral Stenosis (n = 6) and Control subjects (n = 6). Six plasma samples, three each from the control and patient groups were pooled and subjected to low abundance protein enrichment. Pooled plasma samples (crude and equalized) were then subjected to in-solution trypsin digestion separately. Digests were analyzed using nano LC-MSE. Data was acquired with the Protein Lynx Global Server v2.5.2 software and searches made against reviewed Homo sapiens database (UniProtKB) for protein identification. Label-free protein quantification was performed in crude plasma only.
A total of 130 proteins spanning 9–192 kDa were identified. Of these 83 proteins were common to both groups and 34 were differentially regulated. Functional annotation of overlapping and differential proteins revealed that more than 50% proteins are involved in inflammation and immune response. This was corroborated by findings from pathway analysis and histopathological studies on excised tissue sections of stenotic mitral valves. Verification of selected protein candidates by immunotechniques in crude plasma corroborated our findings from label-free protein quantification.
We propose that this protein profile of blood plasma, or any of the individual proteins, could serve as a focal point for future mechanistic studies on Mitral Stenosis. In addition, some of the proteins associated with this disorder may be candidate biomarkers for disease diagnosis and prognosis. Our findings might help to enrich existing knowledge on the molecular mechanisms involved in Mitral Stenosis and improve the current diagnostic tools in the long run.
Electronic supplementary material
The online version of this article (doi:10.1186/1559-0275-11-35) contains supplementary material, which is available to authorized users.
Rheumatic fever; Mitral Stenosis; Plasma proteomics; Inflammation; Immunotechniques
Tripterygium wilfordii Hook F (TwHF), a medicinal plant that has been widely used in Chinese traditional medicine, is proven effective for treating rheumatoid arthritis (RA), but its clinical efficacy and safety remain largely undefined in comparison with conventional synthetic disease modifying anti-rheumatic drugs (DMARDs).
PubMed, Embase, Cochrane Library, CNKI, VIP, CBM, and WanFang Databases. Endpoints were ACR 20, 50, and 70, and the number of withdrawals due to adverse events. Initially, traditional pairwise meta-analysis was performed by using a random-effects model. Then, we performed network meta-analysis to compare different therapies by using frequentist approach.
A total of 22 trials (5255 participants) were identified. By direct comparison, TwHF was superior to sulphasalazine according to ACR 20, 50 and 70. TwHF was superior to placebo according to ACR 20 and 50. By indirect comparisons, TwHF was superior to methotrexate, leflunomide, sulphasalazine, tacrolimus, minocycline and placebo according to ACR 20. Ranking by the Surface under the Cumulative Ranking curve (SUCRA) values showed that TwHF had the greatest probability for being the best treatment option according to ACR 20 (92.0 %) and ACR 50 (81.3 %), and the highest probability to be in the second (57.8 %) ranking position after leflunomide (69.6 %) according to ACR 70. By both direct and indirect comparisons, TwHF caused no more significant withdrawals than the placebo. The SUCRA values showed that TwHF had the highest probability to rank sixth (26.7 %) after the placebo (45.6 %) in causing withdrawals.
Our data suggest that TwHF is effective and safe in the treatment of RA and has better clinical efficacy in terms of ACR 20 and 50 than existing conventional synthetic DMARDs. In the absence of head-to-head treatment comparison, the confidence in these estimates is low. Future comparative efficacy studies are warranted.
Electronic supplementary material
The online version of this article (doi:10.1186/s12906-016-1194-x) contains supplementary material, which is available to authorized users.
Tripterygium wilfordii Hook F; Conventional synthetic DMARDs; Systematic review; Network meta-analysis; Rheumatoid arthritis
Rheumatic fever (RF) and rheumatic heart disease (RHD) are the most-common cardiovascular disease in young people aged <25 years, globally. They are important contributors to cardiovascular morbidity and mortality in Bangladesh. Classical risk factors, i.e. poverty, overcrowding, ignorance, and insufficient health care services were responsible for the high incidence and prevalence of these diseases over the last century. In concert with the progresses in socioeconomic indicators, advances in health sectors, improved public awareness, and antibiotic prophylaxis, acute RF came into control. However, chronic RHD continues to be prevalent, and the actual disease burden may be much higher. RHD predominantly affects the young adults, seriously incapacitates them, follows a protracted course, gets complicated because of delayed diagnosis and is sometimes maltreated. The treatment is often palliative and expensive. Large-scale epidemiological and clinical researches are needed to formulate evidence-based national policy to tackle this important public health issue in future.
Acute rheumatic fever; Rheumatic heart diseases; Bangladesh; Streptococcus; Pharyngitis
Pain patterns vary greatly in the different types of arthritis, from the localized agony without mental overtones in acute gout to the diffuse disorder we call rheumatoid arthritis, where inflammation of many joints, systemic illness, anaemia, anxiety, and depression are usually all present in some degree. Each pain pattern calls for a different therapeutic approach, physical, psychological, and pharmacological. Few patients suffer as much pain and suffering over many years as do chronic arthritics. It is all the more important to instruct them in the essentials of their own treatment. A patient with an occupied and instructed mind usually suffers less than an ignorant and depressed one, fearful of her disease and its complications and of the dark uncertain future that lies ahead.
Rheumatic fever (RF) and rheumatic heart disease (RHD) are still major medical and public health problems mainly in developing countries. Pilot studies conducted during the last five decades in developed and developing countries indicated that the prevention and control of RF/RHD is possible. During the 1970s and 1980s, epidemiological studies were carried out in selected areas of Cuba in order to determine the prevalence and characteristics of RF/RHD, and to test several long-term strategies for prevention of the diseases.
Between 1986 and 1996 we carried out a comprehensive 10-year prevention programme in the Cuban province of Pinar del Rio and evaluated its efficacy five years later. The project included primary and secondary prevention of RF/RHD, training of personnel, health education, dissemination of information, community involvement and epidemiological surveillance. Permanent local and provincial RF/RHD registers were established at all hospitals, policlinics and family physicians in the province. Educational activities and training workshops were organised at provincial, local and health facility level. Thousands of pamphlets and hundreds of posters were distributed, and special programmes were broadcast on the public media to advertise the project.
There was a progressive decline in the occurrence and severity of acute RF and RHD, with a marked decrease in the prevalence of RHD in school children from 2.27 patients per 1 000 children in 1986 to 0.24 per 1 000 in 1996. A marked and progressive decline was also seen in the incidence and severity of acute RF in five- to 25-year-olds, from 18.6 patients per 100 000 in 1986 to 2.5 per 100 000 in 1996. There was an even more marked reduction in recurrent attacks of RF from 6.4 to 0.4 patients per 100 000, as well as in the number and severity of patients requiring hospitalisation and surgical care. Regular compliance with secondary prophylaxis increased progressively and the direct costs related to treatment of RF/RHD decreased with time. The implementation of the programme did not incur much additional cost for healthcare. Five years after the project ended, most of the measures initiated at the start of the programme were still in place and occurrence of RF/RHD was low.
D8/17, an alloantigen found on B lymphocytes, has been reported to be elevated in patients susceptible to rheumatic fever and may be associated with autoimmune types of neuropsychiatric disorders. The pediatric-autoimmune-neuropsychiatric-disorders-associated-with-streptococci model is a putative model of pathogenesis for a group of children whose symptoms of obsessive-compulsive disorder and Tourette's disorder (TD) are abrupt and may be triggered by an infection with group A streptococci. As a test of this model, we have examined D8/17 levels on the B cells of patients with TD and acute rheumatic fever (ARF) along with those on the B cells of normal controls by flow cytometry. We have utilized several different preparations of D8/17 antibody along with a variety of secondary antibodies but have been unable to show an association with an elevated percentage of D8/17-positive, CD19-positive B cells in either ARF or TD. We did find, however, that the percentages of CD19-positive B cells in ARF and TD patients were significantly elevated compared to those in normal controls. Group A streptococcal pharyngitis patients also had an elevated percentage of CD19 B cells, however. These studies failed to confirm the utility of determining the percentage of B cells expressing the D8/17 alloantigen in ARF patients or our sample of TD patients. In contrast, the percentage of CD19-positive B cells was significantly elevated in ARF and TD patients, as well as group A streptococcal pharyngitis patients, suggesting a role for inflammation and/or autoimmunity in the pathogenesis of these disorders.
Acute rheumatic fever (ARF) and rheumatic heart disease are serious autoimmune sequelae to infections with Streptococcus pyogenes. Streptococcal M-proteins have been implicated in ARF pathogenesis. Their interaction with collagen type IV (CIV) is a triggering step that induces generation of collagen-specific auto-antibodies. Electron microscopy of the protein complex between M-protein type 3 (M3-protein) and CIV identified two prominent binding sites of which one is situated in the CB3-region of CIV. In a radioactive binding assay, M3-protein expressing S. pyogenes and S. gordonii bound the CB3-fragment. Detailed analysis of the interactions by surface plasmon resonance measurements and site directed mutagenesis revealed high affinity interactions with dissociation constants in the nanomolar range that depend on the recently described collagen binding motif of streptococcal M-proteins. Because of its role in the induction of disease-related collagen autoimmunity the motif is referred to as “peptide associated with rheumatic fever” (PARF). Both, sera of mice immunized with M3-protein as well as sera from patients with ARF contained anti-CB3 auto-antibodies, indicating their contribution to ARF pathogenesis. The identification of the CB3-region as a binding partner for PARF directs the further approaches to understand the unusual autoimmune pathogenesis of PARF-dependent ARF and forms a molecular basis for a diagnostic test that detects rheumatogenic streptococci.
Understanding disease susceptibility factors and gene-environment interactions may offer valuable insights into the biological mechanisms for the etiology of rheumatic diseases. Defining the contributions of genetic and environmental factors to the pathogenesis of rheumatic diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and ankylosing spondylitis (AS), may have important implications for understanding risk prediction, pathogenic mechanisms, cellular pathways, drug discovery, and prevention strategies. However, rheumatic diseases offer distinct challenges to researchers due to heterogeneity in disease phenotypes, low disease incidence, and geographic variation in both genetic and environmental factors. Emerging research areas, including epigenetics, metabolomics, and the microbiome, may provide additional links between genetic and environmental risk factors in rheumatic disease pathogenesis. This article reviews the methods used to establish genetic and environmental risk factors and to study gene-environment interactions in rheumatic diseases and provides specific examples of successes and challenges for identifying gene-environment interactions in RA, SLE, and AS. Finally, we describe how emerging research strategies may build upon previous discoveries as well as future challenges.
rheumatoid arthritis; systemic lupus erythematosus; ankylosing spondylitis; RA; SLE; AS; environment; genetics; interaction; smoking
Rheumatic diseases affect a significant portion of the population and lead to increased health care costs, disability and even premature mortality; as such, effective preventive measures for these diseases could lead to substantial improvements in public health. Importantly, established and emerging data from natural history studies show that for most rheumatic diseases there is a period of ‘preclinical’ disease development during which abnormal biomarkers or other processes can be detected. These changes are useful to understand mechanisms of disease pathogenesis; in addition, they may be applied to estimate a personal risk of future disease, while individuals are still relatively asymptomatic. Based on this, a hope is to implement effective screening and preventive approaches for some rheumatic diseases, perhaps in the near future. However, a key part of such approaches is a deep understanding of the mechanisms of disease development as well as evidence-based and effective screening and preventive interventions that incorporate disease biology as well as ethical and public health concerns.
Prevention; Rheumatic Diseases
Fc receptors (FcR) interacting with immune complexes (ICs) is a central event in the immune pathogenesis of rheumatoid arthritis (RA). Here we asked if a specific FcR is linked to RA pathogenesis and if FcR activities relate to disease and treatment outcome in early RA.
Material and Methods
Twenty autoantibody-positive RA patients and 33 HC were included. The patients were evaluated before and after treatment with methotrexate and prednisolone. At follow-up, the EULAR response criteria were applied to determine the individual treatment outcomes. Serum immunoglobulin levels were measured and the expression of FcR for IgG (FcγR) and IgA (FcαR) on peripheral blood monocytes were determined by flow cytometry. The monocytic FcγR function was evaluated by human IgG1 and IgG3 IC-binding and TNFα stimulated release. Plasma levels of soluble FcRs (sFcRs) were determined with ELISA.
The IgG1 and IgG3 levels were elevated in the RA sera. The RA monocytes expressed more CD64 and cell surface-bound IgG than HC monocytes, and showed an impaired FcγR function as reflected by changes in IC-binding and decreased IC-stimulated TNFα secretion. These findings correlated significantly with different disease activity markers. Furthermore, sFcRs were elevated in the patient plasma, and sCD64 was specific for RA (compared with a reference group of patients with active psoriatic arthritis). Following treatment, immunoglobulins and sFcR levels were reduced, whereas membrane CD64 was only decreased in patients with good response to treatment.
Early RA patients display increased membrane and soluble CD64 and an impaired FcγR function correlating with joint disease activity. Beneficial responses of anti-rheumatic treatment in patients reduce CD64. These data suggest sCD64 as an important objective biomarker in RA.
Major developments have taken place to further our understanding of the relationship between genetics and the environment in the pathogenesis of rheumatic disorders. The association between HLA markers and human disease is becoming clearer. For instance, HLA-DRW4 frequently occurs in patients with rheumatoid disease, and penicillamine and gold toxicity are seen most often in patients with HLA-DRW2 or DRW3. Antisera to B alloantigens help define the genetic differences between systemic lupus erythematosus and rheumatoid arthritis. As yet, the most dramatic link is that between HLA-B27 and primary ankylosing spondylitis. This same antigen is related, to varying degrees, with other members of the seronegative spondylarthritides and there is strong evidence that this association is related to HLA-B27, itself, rather than an associated disease gene. Nevertheless, some data refute a single gene theory. We are just beginning to learn more about interactions between different genes on the sixth chromosome and genes on other chromosomes.
The sex ratio of the spondylarthritides is now better defined. Sacroiliitis may have a comparable sex distribution although females have more peripheral joint disease and males have greater spinal involvement. Unfortunately, the explanation for these differences remains elusive.
The specific infective agents related to the development of rheumatic disorders are becoming clarified. Chlamydia, Salmonella, Yersinia and Shigella flexneri types 1b and 2a are arthritogenic, while Shigella sonnei appears not to cause disease. Although the Reiter syndrome is now considered a chronic disease, the reason for remissions and relapses remains unclear.