Infectious aspects and the etiopathogenesis of rheumatoid arthritis

Increased incidence of rheumatoid arthritis after COVID-19

An increase in the incidence of inflammatory arthritis after COVID-19 has been reported. Since many diseases exhibit population-specific causal effect sizes, we aimed to evaluate the incidence trends of inflammatory arthritis, including rheumatoid arthritis (RA), after COVID-19 in a large admixed Colombian population. Data analysis for this retrospective, population-based cohort study was carried out using the COOSALUD EPS registry. The following codes were selected for analyses: M059, seropositive RA, M069, unspecified RA, M060 seronegative RA, and other RA-related diagnoses: M064, M139, M068, M058, M130 and M053. The study period was limited to January 01, 2018, through December 31, 2022. Incidence rates (IRs) and incidence rate ratios (IRRs) were assessed. A Cox survival model was built to evaluate the influence of age, gender, and COVID-19 vaccination status on the development of inflammatory arthritis. A bioinformatic analysis was performed to evaluate the homology between SARS-CoV-2 and autoantigen peptides related to RA. The entire population study comprised 3,335,084 individuals. During the pandemic period (2020-2022) the total IIR for seropositive and unspecified RA were 1.60 (95% CI, 1.16-2.22) and 2.93 (95% CI, 2.04-4.19), respectively, and the IIR for overall RA-related diagnosis was 2.01 (95% CI 1.59-2.53). The age groups hazard ratios (HRs) were increased until the age group of 51-60 years (HR: 9.16; 95% CI, 7.24-11.59) and then decreased slightly in the age group 61 years or older (HR: 5.364; 95% CI, 4.24-6.78) compared to those within 18-30 years. Men were less at risk than women to develop inflammatory arthritis (HR: 0.21; 95% CI, 0.18-0.24). The greater time since COVID-19 diagnosis was associated with a lower likelihood of developing inflammatory arthritis (HR: 0.99; 95% CI:0.998-0.999). Vaccination (all types of COVID-19 vaccines included) did not prevent the development of inflammatory arthritis after COVID-19. Low identity was found between the SARS-CoV-2 ORF1ab antigen and the human antigens Poly ADP-ribose polymerase 14 and Protein mono-ADP-ribosyltransferase PARP9 isoform D (39% and 29%, respectively). In conclusion, our study confirms increased incidence of inflammatory arthritis, including RA, after COVID-19, with the greatest increase occurring before the first year post-covid. Women in their fifties were more susceptible. Further research is required to examine the effectiveness of vaccination in preventing post-COVID inflammatory arthritis and the mechanisms implicated in the development of RA after COVID-19.

Helicobacter pylori-Related Extraintestinal Manifestations—Myth or Reality

It is well documented that Helicobacter pylori (H. pylori) can cause both gastrointestinal and extraintestinal manifestations. The latter one represents a major burden in terms of diagnosis and treatment. H. pylori-associated systemic subclinical inflammation is mostly responsible for the development of extraintestinal manifestations, and its early eradication might result in preventing all adverse events related to their occurrence. Thus, it was suggested that H. pylori might be associated with iron deficiency anemia, thrombocytopenia (immune thrombocytopenic purpura), Schonlein Henoch purpura, failure to thrive, vitamin B12 deficiency, diabetes mellitus, body mass index, cardiovascular diseases, as well as certain neurological conditions. Nevertheless, studies showed both pros and cons in terms of the role of H. pylori in the development of previously mentioned clinical entity underlining the crucial need for further studies on these topics. Although most of these extraintestinal manifestations occur during adulthood, we must not forget that H. pylori infection is acquired mainly during childhood, and thus its early diagnosis and eradication might represent the cornerstone in the prevention of H. pylori-induced inflammatory status and consequently of all related extraintestinal conditions.

Helicobacter Pylori and Autoimmune Diseases: Involving Multiple Systems

The modern Gastroenterology have witnessed an essential stride since Helicobacter pylori was first found in the stomach and then its pathogenic effect was discovered. According to the researches conducted during the nearly 40 years, it has been found that this bacterium is associated with a natural history of many upper gastrointestinal diseases. Epidemiological data show an increased incidence of autoimmune disorders with or after infection with specific microorganisms. The researches have revealed that H. pylori is a potential trigger of gastric autoimmunity, and it may be associated with other autoimmune diseases, both innate and acquired. This paper reviews the current support or opposition about H. pylori as the role of potential triggers of autoimmune diseases, including inflammatory bowel disease, autoimmune thyroiditis, type 1 diabetes mellitus, autoimmune liver diseases, rheumatoid arthritis, idiopathic thrombocytopenic purpura, systemic lupus erythematosus, as well as Sjogren’s syndrome, chronic urticaria and psoriasis, and tried to explain the possible mechanisms.

Helicobacter pylori and its association with autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis and Sjögren syndrome

Helicobacter pylori (H. pylori) is a gram-negative bacterium that adapts to the gastric mucosa and provokes symptoms associated with gastritis. Chronic H. pylori infection in patients with a genetic predisposition can trigger autoimmune diseases due to the immune interaction of cellular and humoral responses. Infections are a triggering factor for systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren syndrome (SS), although the association between H. pylori and these diseases is unclear. Therefore, we reviewed this interaction and its clinical importance.

Cytomegalovirus infection: friend or foe in rheumatoid arthritis?

Human cytomegalovirus (HCMV) is a β-herpesvirus that causes inflammation and remains for life in a latent state in their host. HCMV has been at the center of many hypotheses regarding RA.

We have recently shown that HCMV infection impairs bone erosion through the induction of the mRNA-binding protein QKI5. Latently infected RA patients display a slower progression of bone erosion in patients from a national cohort. Our observations question the possible association between HCMV and the pathophysiology of RA. In this review, we examine the possibility that HCMV may be an aggravating factor of inflammation in RA while protecting from bone erosion. We also assess its relationship with other pathogens such as bacteria causing periodontitis and responsible for ACPA production.

This review thus considers whether HCMV can be regarded as a friend or a foe in the pathogenesis and the course of RA.

Association between rheumatoid arthritis and genetic variants of natural resistance-associated macrophage protein 1 gene: A meta-analysis

AIM

To evaluate the association between natural resistance-associated macrophage protein 1 (NRAMP1) polymorphisms and rheumatoid arthritis (RA).

METHOD

All related studies were retrieved and screened from PubMed, CNKI and Web of Science. Pooled odds ratios (ORs) and 95% CIs were assessed for the strength of association between NRAMP1 and RA. Publication bias was measured by Begg's funnel plot and Egger's regression test. The robustness of this meta-analysis was detected by sensitivity analysis.

RESULTS

A total of five eligible publications were included in the present meta-analysis. The polled data showed no association between RA and NRAMP1 D543N and 1729 + 55del4 in the allele model. However, the relationship between RA and NRAMP1 INT4 was statistically significant (OR 1.65, 95% CI 1.14-2.38). Genotypic analysis demonstrated that there were no associations between RA and NRAMP1 D543N, 1729 + 55del4 and INT4 in homozygous comparison (D543N: OR 0.97, 95% CI 0.15-6.09; 1729 + 55del4: OR 1.19, 95% CI 0.29-24.88; INT4: OR 3.18, 95% CI 0.62-16.26), dominant model (D543N: OR 1.04, 95% CI 0.61-61.78; 1729 + 55del4: OR 1.41, 95% CI 0.81-2.47; INT4: OR 1.22, 95% CI 0.72-2.06) and recessive model (D543N: OR 0.93, 95% CI 0.15-5.91; 1729 + 55del4: OR 0.99, 95% CI 0.26-3.86; INT4: OR 2.95, 95% CI 0.61-14.16). In heterozygous comparison, it no association was shown between RA and NRAMP1 D543N and INT4, excepting NRAMP1 1729 + 55del4 (OR 1.73, 95% CI 1.17-2.56). Further subgroup analysis indicated that NRAMP1 1729 + 55del4 and INT4 were related to RA in Asia and in the Hardy-Weinberg equilibrium group. There exists no publication bias in this meta-analysis.

CONCLUSION

This meta-analysis indicated that NRAMP1 1729 + 55del4 and INT4 confer susceptibility to RA.

In seroconverted rheumatoid arthritis patients a multi-reactive anti-herpes IgM profile is associated with disease activity

Conflicting results have been reported regarding human herpes virus (HHV) reactivation in patients with rheumatoid arthritis (RA). To explore this link, 74 RA patients were selected and compared to 42 first degree relatives (FDR) from probands with RA and 25 healthy controls from the Tatarstan women cohort. The serological analysis was done by testing anti-HSV/CMV/EBV IgM, IgG, plus the IgG avidity index, and completed by evaluating HSV/CMV/EBV DNA by PCR. Results from these analyses reveal: (i) a long lasting infection of HHV in RA, FDR and healthy controls (IgG seroconversion >97%); (ii) an elevated IgM anti-HHV response in seroconverted RA patients which is related to HSV1/2 reactivation (HSV1/2 PCR+); and (iii) a multi-reactive IgM HHV burden profile associated with disease activity (DAS28). In conclusion, HSV1/2 reactivation in seroconverted RA patients is associated with an abnormal anti-HHV immune response, which was reflected in IgM HHV burden, and in activity disease profile.

Frequency and significance of parvovirus B19 infection in patients with rheumatoid arthritis

The present study aims to clarify the possible involvement of parvovirus B19 (B19V) infection in rheumatoid arthritis (RA) pathogenesis by investigating the presence of B19V infection markers (genomic sequences and virus-specific antibodies) in association with the level of cytokines and RA clinical activity and aggressiveness. A total of 118 RA patients and 49 age- and sex-matched healthy volunteers were enrolled in the study. Nested PCR was used to detect B19V sequences in whole blood and cell-free plasma DNA, ELISA to detect virus-specific antibodies and cytokine levels in plasma and recomLine dot blot assay for antibodies to separate B19V antigens. The detection frequency of B19V DNA was higher in patients with RA (25.4 %) in comparison with healthy persons (18.4 %). B19V DNA in cell-free plasma (B19⁺p) was detected significantly often in RA patients in comparison with healthy controls (13.6 vs 2 %; P=0.0002). RA B19⁺p patients had higher disease activity and aggressiveness, decreased haemoglobin and increased erythrocyte sedimentation rates. IL-6 plasma levels were significantly higher in RA patients than in controls. Within the RA patients’ group the IL-6 level was significantly increased in B19⁺p patients with disease activity scores of DAS28>5.2, high C-reactive protein and low haemoglobin. Contrary to the healthy controls, the majority of RA B19⁺p patients did not have antibodies to VP-1S (VP1u) and VP-N (N-terminal half of structural proteins VP1 and VP2), which correspond to the epitopes of neutralizing antibodies. These results indicate that B19V infection at least in some patients is involved in RA pathogenesis.

Ins and outs of Helicobacter pylori association with autoimmune rheumatic diseases

Helicobacter pylori (H. pylori) infection is widely prevalent throughout worldwide. H. pylori manage a long-term survival in hostile environment of human stomach leading to peptic ulcer diseases and gastric cancer. But mostly infected person remains asymptomatic. Its chronic interaction with immune system makes H. pylori as an attractive candidate for the researchers to study its association with autoimmune diseases. This article presents a review of the literature on the association of H. pylori infection in selective autoimmune rheumatic diseases (RD). The authors used MeSH terms “Helicobacter pylori” with “rheumatoid arthritis,”“systemic lupus erythematosus,” or “fibromyalgia” to search PubMed database. All relevant studies identified were included. Despite extensive medical advancement many questions on role of H. pylori infection in autoimmune RD still remain unanswered. Further studies are therefore needed to address the role of H. pylori in pathogenesis of RD.

Occasional presence of herpes viruses in synovial fluid and blood from patients with rheumatoid arthritis and axial spondyloarthritis

Viral agents have been suspected as participants of immune-mediated disorders. In the case of rheumatic diseases, the synovial joint cavity represents a secluded area of inflammation which could harbor etiological agents. We analyzed by polymerase chain reaction the possible presence of DNA from various herpes viruses in blood and synovial fluid from patients with either rheumatoid arthritis (n = 18), axial spondyloarthritis (n = 11), or osteoarthritis (n = 8). Relevant findings were as follows: DNA from varicella zoster virus was found in synovial fluid but not in blood mononuclear cells from 33 % of patients with rheumatoid arthritis and in 45 % of patients with axial spondyloarthritis but not in patients with osteoarthritis. Also, DNA from herpes simplex viruses 1 and 2 was found both in the blood and in the synovial fluid from 33 % of patients with rheumatoid arthritis. Our results indicate the occasional presence of DNA from herpes viruses in patients with rheumatoid arthritis or with axial spondyloarthritis. However, these findings might represent a parallel epiphenomenon of viral activation associated either with immunosuppressive therapy or with primary immune disturbances, rather than the etiological participation of herpes viruses in these disorders.

Prevalence of celiac disease in latin america: a systematic review and meta-regression

BACKGROUND

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of gluten in susceptible individuals, and its prevalence varies depending on the studied population. Given that information on CD in Latin America is scarce, we aimed to investigate the prevalence of CD in this region of the world through a systematic review and meta-analysis.

METHODS AND FINDINGS

This was a two-phase study. First, a cross-sectional analysis from 981 individuals of the Colombian population was made. Second, a systematic review and meta-regression analysis were performed following the Preferred Reporting Items for Systematic Meta- Analyses (PRISMA) guidelines. Our results disclosed a lack of celiac autoimmunity in the studied Colombian population (i.e., anti-tissue transglutaminase (tTG) and IgA anti-endomysium (EMA)). In the systematic review, 72 studies were considered. The estimated prevalence of CD in Latin Americans ranged between 0.46% and 0.64%. The prevalence of CD in first-degree relatives of CD probands was 5.5%. The coexistence of CD and type 1 diabetes mellitus varied from 4.6% to 8.7%, depending on the diagnosis methods (i.e., autoantibodies and/or biopsies).

CONCLUSIONS

Although CD seems to be a rare condition in Colombians; the general prevalence of the disease in Latin Americans seemingly corresponds to a similar scenario observed in Europeans.

Role of Helicobacter pylori infection in autoimmune systemic rheumatic diseases

The relationship between infection and autoimmunity has been increasingly defined over the last 20 years. The systemic rheumatic diseases are characterized by dysregulation of the immune system resulting in a loss of tolerance to self-antigen. The exact etiology for the majority of these diseases is unknown; however, a complex combination of host and environmental factors are believed to play a pivotal role. Helicobacter pylori (H. pylori) is one of the most widely studied infectious agents proposed as agents triggering autoimmune response. The persistent presence of H. pylori in the gastric mucosa results in chronic immune system activation with ongoing cytokine signaling, infiltration of gastric mucosa by neutrophils, macrophages, lymphocytes, as well as production of antibodies and effector T-cells. Various mechanisms have been proposed in an attempt to explain the extra-intestinal manifestations of H. pylori infections. These include: molecular mimicry, endothelial cell damage, superantigens and microchimerism. I performed a systematic literature review using the keywords “rheumatoid arthritis”, “Sjögren’s syndrome”, “systemic sclerosis”, “systemic lupus erythematosus”, “Helicobacter pylori” and “pathogenesis”. A systematic literature search was carried out in MEDLINE; EMBASE; Cochrane Library and ACR/EULAR meeting abstracts. In systemic rheumatic diseases H. pylori infection prevalence alone should not be expected to provide sufficient evidence for or against a pathologic role in the disease. In this article I review studies examining the potential involvement of H. pylori infection in autoimmune systemic rheumatic diseases. Further studies of the immunological response to H. pylori and its role in the pathogenesis of systemic rheumatic diseases are warranted.

Arthritis susceptibility and the gut microbiome

Rheumatoid arthritis (RA) is an autoimmune disease with unknown etiology though both genetic and environmental factors have been suggested to be involved in its pathogenesis. While infections and other environmental factors (e.g. smoking) have been studied extensively and show some association, a direct link between all the factors has been difficult to prove. With the recent advances in technology, it has become possible to sequence the commensals that are residing in our gut. The gut microbiome may provide the missing link to this puzzle and help solve the mystery of many leaky gut syndromes. The gut commensals are involved in maintaining host immune homeostasis and function suggesting that they might be critical in altering the immune system, which leads to autoimmune diseases like RA. Mouse models support the role of the gut microbiota in predisposition to RA. If that is true, the power of gut-derived commensal can be harnessed to our benefit by generating a biomarker profile along with genetic factors to define individuals at risk and by altering the gut microbial composition using various means.

Immunomodulation in human and experimental arthritis: including vitamin D, helminths and heat-shock proteins

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that is mainly directed to the joints, affecting the synovial membrane, the cartilage and also the bone. This disease affects 1% to 2% of the world population and is associated with significant morbidity and increased mortality. RA experimental models have allowed a great deal of information to be translated to the corresponding human disease. This review summarizes some of the most relevant findings targeting immunomodulation in arthritis. Some general guidelines to choose an adequate experimental model and also our experience with arthritis are supplied.

Gene-environment interaction in autoimmune disease

Autoimmune disease manifests in numerous forms, but as a disease group is relatively common in the population. It is complex in aetiology, with genetic and environmental determinants. The involvement of gene variants in autoimmune disease is well established, and evidence for significant involvement of the environment in various disease forms is growing. These factors may act independently, or they may interact, with the effect of one factor influenced by the presence of another. Identifying combinations of genetic and environmental factors that interact in autoimmune disease has the capacity to more fully explain disease risk profile, and to uncover underlying molecular mechanisms contributing to disease pathogenesis. In turn, such knowledge is likely to contribute significantly to the development of personalised medicine, and targeted preventative approaches. In this review, we consider the current evidence for gene-environment (G-E) interaction in autoimmune disease. Large-scale G-E interaction research efforts, while well-justified, face significant practical and methodological challenges. However, it is clear from the evidence that has already been generated that knowledge on how genes and environment interact at a biological level will be crucial in fully understanding the processes that manifest as autoimmunity.

Helicobacter pylori and autoimmune disease: Cause or bystander

Helicobacter pylori (H. pylori) is the main cause of chronic gastritis and a major risk factor for gastric cancer. This pathogen has also been considered a potential trigger of gastric autoimmunity, and in particular of autoimmune gastritis. However, a considerable number of reports have attempted to link H. pylori infection with the development of extra-gastrointestinal autoimmune disorders, affecting organs not immediately relevant to the stomach. This review discusses the current evidence in support or against the role of H. pylori as a potential trigger of autoimmune rheumatic and skin diseases, as well as organ specific autoimmune diseases. We discuss epidemiological, serological, immunological and experimental evidence associating this pathogen with autoimmune diseases. Although over one hundred autoimmune diseases have been investigated in relation to H. pylori, we discuss a select number of papers with a larger literature base, and include Sjögrens syndrome, rheumatoid arthritis, systemic lupus erythematosus, vasculitides, autoimmune skin conditions, idiopathic thrombocytopenic purpura, autoimmune thyroid disease, multiple sclerosis, neuromyelitis optica and autoimmune liver diseases. Specific mention is given to those studies reporting an association of anti-H. pylori antibodies with the presence of autoimmune disease-specific clinical parameters, as well as those failing to find such associations. We also provide helpful hints for future research.

Autoimmune thyroid disease in rheumatoid arthritis: a global perspective

Objective. To determine the prevalence and impact of autoimmune thyroid disease (AITD) in patients with rheumatoid arthritis (RA). Methods. Eight-hundred patients were included. The association between AITD and RA was analyzed was analyzed by bivariate and multivariate analysis. In addition, a literature review was done focusing on geographical variations. Results. In our cohort the prevalence of AITD was 9.8% while the presence of antibodies was 37.8% for antithyroperoxidase enzyme (TPOAb) and 20.8% for antithyroglobulin protein (TgAb). The presence of type 2 diabetes, thrombosis, abnormal body mass index, and a high educational level was positively associated with AITD. The literature review disclosed a geographical variation of AITD in RA ranging from 0.5% to 27%. Autoantibody prevalence ranges from 6% to 31% for TgAb, 5% to 37% for TPOAb, and from 11.4% to 32% for the presence of either of the two. Conclusion. AITD is not uncommon in RA and should be systematically assessed since it is a risk factor for developing diabetes and cardiovascular disease. These results may help to further study the common mechanisms of autoimmune diseases, to improve patients' outcome, and to define public health policies. An international consensus to accurately diagnose AITD is warranted.

Role of Helicobacter pylori infection in autoimmune diseases

PURPOSE OF REVIEW

The etiology of most autoimmune diseases remains elusive. Prevailing evidence suggests an environmental trigger in a genetically susceptible individual. Helicobacter pylori (H. pylori) have managed to survive in a hostile environment in their host for long period and have evaded eradication by the immune system. Its chronic interaction with the immune system and the ubiquitous presence worldwide makes H. pylori an ideal candidate to study as a trigger of autoimmune phenomena. In this review, we would present data regarding the interplay between H. pylori and various components of the immune system and its association with various autoimmune diseases.

RECENT FINDINGS

Strong associations of H. pylori with some autoimmune diseases such as immune thrombocytopenia have been found; but most other autoimmune disease studies have revealed conflicting data. The chronic survival of H. pylori in humans is possible because of an overall downregulation of the body's immune response. In addition to this overall effect on the immune system, there are clinical and epidemiological data suggestive of H. pylori infection having a protective role in some autoimmune diseases.

SUMMARY

Based on our review H. pylori status should be checked and treated only in certain autoimmune diseases such as ITP. For the majority of the autoimmune diseases, the role of H. pylori remains controversial signifying need for further research.

The immunopathology of liver granulomas in primary biliary cirrhosis

Liver granulomas and elevated serum IgM are commonly observed in patients with primary biliary cirrhosis (PBC) but their pathogenetic significance remains largely unknown. To address this issue we performed an extensive immunostaining and colocalization study of markers associated with dendritic cells and IgM in a large cohort of tissue samples from PBC and control livers as well as from non-hepatic granulomatous diseases. First, the classical dendritic cell CD11c marker is highly expressed and more sensitive than classical hematoxylin-eosin staining in detecting granulomas associated with PBC and other conditions. Second, PBC cases with CD11c-positive granulomas have significantly higher serum IgM levels and earlier disease stages. Third, granulomas from PBC and other diseases demonstrate markers of dendritic cell immaturity, i.e. CD11b, reduced MHC II, IL-23, CCR7 and CD83 expression, and elevated C1q expression. Lastly, B cells and IgM-positive plasma cells are largely represented around PBC granulomas along with macrophages. In conclusion, our comprehensive immunohistochemical study suggests that dendritic cells are key to the pathogenesis of granulomas, regardless of their origin. More specifically, PBC liver granulomas may result from the interaction between immature dendritic cells and IgM.

The future of autoimmunity

There have been enormous strides in our understanding of autoimmunity. These strides have come under the umbrellas of epidemiology, immunological phenotype and function, disease definitions and classification and especially new therapeutic reagents. However, while these advances have been herculean, there remains enormous voids. Some of these voids include genetic susceptibility and the interaction of genes and environment. The voids include induction of tolerance in preclinical disease and definitions of host susceptibility and responses to the expensive biologic agents. The voids include the so-called clustering of human autoimmune diseases and the issues of whether the incidence is rising in our western society. Other voids include the relationships between microbiology, vaccination, gut flora, overzealous use of antibiotics, and the role of nanoparticles and environmental pollution in either the induction or the natural history of disease. One cannot even begin to address even a fraction of these issues. However, in this special issue, we are attempting to discuss clinical issues in autoimmunity that are not usually found in generic reviews. The goal is to bring to the readership provocative articles that ultimately will lead to improvement in patient care.

Geographical differences in autoantibodies and anti-infectious agents antibodies among healthy adults

Much is known about the geoepidemiology of defined autoimmune diseases (AD); however, there is currently limited data regarding the prevalence of autoantibodies among healthy populations of different geographical areas. The aim of this study was to evaluate a large profile of autoantibodies in healthy adults from distinct global regions as well as the prevalence of anti-infectious agents antibodies in those regions. Sera samples from 557 healthy donors were obtained at six centers located in different countries (i.e., Italy, Netherlands, Israel, Mexico, Columbia, Papua New Guinea (Kitavans)). Sera were tested for the presence of antinuclear antibodies (ANA) and autoantibodies associated with thrombophilia, vasculitis, and gastrointestinal (GI) disease. Sera samples were also screened for antibodies against infectious agents (i.e., EBV, CMV, HBV, Helicobacter pylori, Treponema pallidum, and Toxoplasma gondii). Tests were performed using the BioPlex 2200 or ELISA kits (Bio-Rad Laboratories, USA). We found a significant gradient of ANA positivity among the groups: 45% of Columbians, 38% of Kitavans, 26% of Mexicans, 12% of Italians, 12% of Dutch, and 11% of Israelis were ANA positive. Geographical differences were also observed regarding the prevalence of specific autoantibodies, namely ANA: anti-dsDNA, chromatin, SmRNP, Ro/SSA, La/SSB, Scl70; GI associated: antigliadin; and thrombophilia-associated: anti-β2GP1 and prothrombin. Additionally, significant differences were observed regarding serological markers of all infectious agents screened. The observed variance between healthy ethno-geographical distinct populations in prevalence of autoantibodies may represent different genetic or environmental (e.g., prior exposure to infection) influences. Thus may illuminate possible causes of geoepidemiological differences in AD.

Infection and rheumatoid arthritis: still an open question

PURPOSE OF REVIEW

This review focuses on recent research that explores the role of infectious organisms in the development of autoimmunity and rheumatoid arthritis (RA).

RECENT FINDINGS

Human and animal studies provide further evidence supporting a role for the periodontal pathogen, Porphyromonas gingivalis, in the development of RA. The microbiome plays a key role in the developing immune system. Alterations in the bowel microbiome lead to altered innate and adaptive immune responses potentially relevant to the development or persistence of RA.

SUMMARY

Microbes and the host response to microbes are important factors in the maintenance of health. Abnormalities or imbalances in these responses can lead to the development of autoimmune inflammatory conditions such as RA.

Arthritis after infection with Chikungunya virus

Chikungunya virus (CHIKV) is an emerging alphavirus responsible for several infectious outbreaks in the world. After an acute stage of illness characterised by a fever-arthralgia syndrome and rash, joint disorders due to CHIKV infection can sometimes persist for several months or years. Chronic arthritis after this emerging disease is well documented, and similarities to rheumatoid arthritis have been described. Knowledge of the geographical epidemiology of CHIKV infection is crucial for better control of the disease. Thus, recent outbreaks have led to several studies, which have highlighted the need for a better understanding of the clinical features of Chikungunya (CHIK) and beginning knowledge of the pathophysiogenesis, which can lead to further research.

Cutting-edge issues in organ-specific autoimmunity

There have been numerous methods and ways to classify autoimmune diseases. By far, the most traditional has been to separate immune-mediated pathology into organ-specific and organ-non-specific diseases. The classic systemic autoimmune diseases are, of course, rheumatoid arthritis and systemic lupus. The classic organ-specific autoimmune diseases have been autoimmune thyroiditis and autoimmune gastritis. However, as our understanding of the loss of tolerance has expanded, so has the long list of autoimmune diseases. In many cases, the distinction between organ-specific and organ-non-specific or systemic autoimmunity becomes a blur. In this issue, we discuss recent concepts in autoimmune pancreatitis, primary sclerosing cholangitis, Goodpasture's syndrome, myofasciitis, type I diabetes, polymyositis, autoimmune thyroid disease, IgA nephropathy, autoimmune uveitis, and ANCA-associated vasculitis. Common themes on both etiology and effector mechanisms are described throughout these papers with an attempt to provide a cutting-edge overview.

Autoimmune bullous diseases the spectrum of infectious agent antibodies and review of the literature

Pemphigus and bullous pemphigoid are two autoimmune diseases that have a similar pathogenesis. Both have a genetic predisposition which promotes the production of auto-antibodies targeted against different components of the epidermal desmosome and hemidesmosome. Environmental factors play an important role in the pathogenesis of this autoimmune disease. Among these, the role of infectious agents was debated as a causative factor. We sought to determine a possible connection between various infectious agents and autoimmune bullous disease (ABD). A cohort of 148 serum samples of patients with pemphigus, bullous pemphigoid and controls was screened for evidence of a prior infection with HBV, HCV, EBV, CMV, Helicobacter pylori, Toxoplasma gondii and Treponema pallidum, utilizing the Bio-Rad BioPlex 2200 system as well as ELISA assays to complete the panel. HBV, HCV, H. pylori, T. gondii and CMV were demonstrated to have significantly higher prevalence of antibodies in patients with pemphigus and bullous pemphigoid in comparison to controls. Among them, we found a novel association between H. pylori and ABD. Our study suggests a contributing role for HBV, HCV, H. pylori, T. gondii and CMV in inducing ABD in the genetically susceptible host.

Helicobacter pylori and autoimmune diseases

Helicobacter pylori (H. pylori) is a widely prevalent microbe, with between 50 and 80% of the population infected worldwide. Clinically, infection with H. pylori is commonly associated with peptic ulcer disease, but many of those infected remain asymptomatic. H. pylori has evolved a number of means to affect the host immune response and has been implicated in many diseases mitigated by immune dysregulation, such as immune thrombocytopenic purpura (ITP), atrophic gastritis, and mucosa associated lymphoid tissue (MALT) lymphoma. Autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Sjogren's syndrome, are the result of a dysregulated host immune system which targets otherwise healthy tissues. The exact etiology of autoimmune diseases is unclear, but it has long been suggested that exposure to certain environmental agents, such as viral and bacterial infection or chemical exposures, in genetically susceptible individuals may be the catalyst for the initiation of autoimmune processes. Because of its prevalence and ability to affect human immune function, many researchers have hypothesized that H. pylori might contribute to the development of autoimmune diseases. In this article, we review the available literature regarding the role of chronic H. pylori infection in various autoimmune disease states.

Presence of autoimmune antibody in chikungunya infection

Chikungunya infection has recently re-emerged as an important arthropod-borne disease in Thailand. Recently, Southern Thailand was identified as a potentially endemic area for the chikungunya virus. Here, we report a case of severe musculoskeletal complication, presenting with muscle weakness and swelling of the limbs. During the investigation to exclude autoimmune muscular inflammation, high titers of antinuclear antibody were detected. This is the report of autoimmunity detection associated with an arbovirus infection. The symptoms can mimic autoimmune polymyositis disease, and the condition requires close monitoring before deciding to embark upon prolonged specific treatment with immunomodulators.