Does pregnancy provide vaccine-like protection against rheumatoid arthritis?

The 'communicatome' of pregnancy: spotlight on cellular and extravesicular chimerism

Communication via biological mediators between mother and fetus are key to reproductive success and offspring's future health. The repertoire of mediators coding signals between mother and fetus is broad and includes soluble factors, membrane-bound particles and immune as well as non-immune cells. Based on the emergence of technological advancements over the last years, considerable progress has been made toward deciphering the "communicatome" between fetus and mother during pregnancy and even after birth. In this context, pregnancy-associated chimerism has sparked the attention among immunologists, since chimeric cells-although low in number-are maintained in the allogeneic host (mother or fetus) for years after birth. Other non-cellular structures of chimerism, e.g. extracellular vesicles (EVs), are increasingly recognized as modulators of pregnancy outcome and offspring's health. We here discuss the origin, distribution and function of pregnancy-acquired microchimerism and chimeric EVs in mother and offspring. We also highlight the pioneering concept of maternal microchimeric cell-derived EVs in offspring. Such insights expand the understanding of pregnancy-associated health or disease risks in mother and offspring.

Impact of frailty severity and severe pain on cognitive function for community-dwelling older adults with arthritis: a cross-sectional study in Korea

Pain is a major symptom of arthritis in older adults, often leading to frailty and cognitive decline. However, few studies have investigated the relationship among pain, frailty, and cognitive function in older adults with arthritis. This study aimed to investigate the factors influencing cognitive function and the impact of frailty severity and pain on cognitive function in older adults with arthritis using a Korean population-based dataset. This cross-sectional descriptive study involved the secondary data of 1089 participants from the seventh and eighth waves of the Korean Longitudinal Study on Aging. We examined general characteristics, health behaviors, health conditions (including severe pain and frailty), and cognitive function. Participants were categorized based on the presence or absence of pain severity and frailty status as follows: robust, only severe pain, only prefrail, prefrail with severe pain, only frail, and frail with severe pain. Multiple linear regression analysis was performed to establish correlations between groups and cognitive function. The only-prefrail group was the largest (19.7%) among participants experiencing either pain or frailty. Advanced age, sex, level of education, and visual and hearing impairments were significantly associated with cognitive function. Compared to the robust group, only prefrail (β = -1.54, confidence interval [CI] = - 2.33; - 0.76), prefrail with severe pain (β = - 2.69, CI = - 3.52; - 1.87), only frail (β = - 4.02, CI = - 5.08; - 2.97), and frail with severe pain (β = - 5.03, CI = - 5.99; - 4.08) groups were associated with lower Mini-Mental State Examination scores. The study confirmed that severe pain alone does not significantly impact cognitive function in older adults with arthritis. To prevent cognitive decline in this group, assessment of both pain and frailty severity is essential to predict high-risk groups and provide appropriate interventions, such as transfer to hospitals or primary clinics according to the severity of pain and frailty.

A history of cesarean section and future maternal long-term risk for neoplasms: a population-based cohort study

OBJECTIVE

Mode of delivery has long-term implications on the mother, including recent data regarding the level of transmission of fetal microchimeric cells (FMc) and their possible effect on cancer development. We aimed to evaluate the association between cesarean section (CS) and future risk for neoplasms.

STUDY DESIGN

A population-based cohort analysis comparing the long-term risk for neoplasms between patients that delivered only by CS to those that delivered only vaginally (VD). Neoplasms were pre-defined based on ICD-9 codes. Deliveries occurred between the years 1991-2017 in a tertiary medical center. Kaplan-Meier survival curves were used to compare the cumulative incidence of neoplasms and Cox proportional hazards models were constructed to control for confounders.

RESULTS

During the study period 105,992 patients met the inclusion criteria; 14150 (13.4%) of patients had only CS and 91842 (86.6%) had VD (comparison group). The CS group had significantly higher incidence of benign and malignant neoplasms (4.73 per 1000 patient-years versus 3.88 per 1000 patient-years, OR = 1.26, 95% CI 1.16-1.37; p = 0.001; 2.19 per 1000 patient-years of follow up versus 1.93 per 1000 patient-years, OR = 1.16, 95% CI 1.03-1.31; p = 0.013). Specifically, the CS group had higher incidence of uterine cancer (1.2 versus 0.06 per 1000 patient-years, OR = 1.97, 95% CI 1.14-3.39; p = 0.013). The cumulative incidence of benign, malignant and uterine neoplasms was significantly higher in the CS group (Log rank test p = 0.001; 0.036 and 0.014; respectively). Importantly, no significant association was found with breast and ovarian malignancies." When performing a Cox regression model controlling for confounders, the risk for malignancy-related hospitalizations remained significant (adjusted HR = 1.22, 95% CI 1.01-1.48; p = 0.031) but not for uterine cancer (adjusted HR = 1.6, 95% CI 0.9-2.8; p = 0.103).

CONCLUSION

Our findings provide support to linkage between delivery by cesarean section and future maternal malignancy.

Global epidemiology of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that predominantly affects the joints. The prevalence of RA varies globally, with generally a higher prevalence in industrialized countries, which may be explained by exposures to environmental risk factors, but also by genetic factors, differing demographics and under-reporting in other parts of the world. Over the past three decades, strong trends of the declining severity of RA probably reflect changes in treatment paradigms and overall better management of the disease. Other trends include increasing RA prevalence. Common risk factors for RA include both modifiable lifestyle-associated variables and non-modifiable features, such as genetics and sex. A better understanding of the natural history of RA, and of the factors that contribute to the development of RA in specific populations, might lead to the introduction of specific prevention strategies for this debilitating disease.

What is the impact of sex hormones on the pathogenesis of rheumatoid arthritis?

Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease and has a female predominance of around 3:1. The relationship between sex hormones and RA has been of great interest to researchers ever since Philip Hench's observations in the 1930's regarding spontaneous disease amelioration in pregnancy. Extensive basic scientific work has demonstrated the immunomodulatory actions of sex hormones but this therapeutic potential has not to date resulted in successful clinical trials in RA. Epidemiological data regarding both endogenous and exogenous hormonal factors are inconsistent, but declining estrogen and/or progesterone levels in the menopause and post-partum appear to increase the risk and severity of RA. This review assimilates basic scientific, epidemiological and clinical trial data to provide an overview of the current understanding of the relationship between sex hormones and RA, focusing on estrogen, progesterone and androgens.

Gynecological/Obstetric Background and Rheumatoid Arthritis: A Cross-sectional Study in Brazilian Patients

OBJECTIVE

 To study a sample of rheumatoid arthritis (RA) patients for their gynecological/obstetric history and compare them to controls to determine their influences on number of pregnancies, menarche, menopause and reproductive years following RA onset.

METHODS

 This is a cross-sectional study of 122 RA patients and 126 controls. Patients and controls were questioned about age of menarche, age of menopause, number of pregnancies and abortions. Reproductive years were calculated as the difference between age at menopause and age at menarche. For comparison, we used the Mann-Whitney, unpaired t, chi-squared, and Spearman tests. The adopted significance was 5%.

RESULTS

 In the RA patients with disease beginning in the postmenopausal years, the period of reproductive years (age at menopause - age of menarche) showed a positive correlation with age at disease onset (rho = 0.46; 95% confidence interval [CI] = 0.20-0.55 with p = 0.0008). The number of pregnancies was higher in patients with postmenopausal disease onset when compared with those with premenopausal disease onset (median of 3 with interquartile range [IQR] = 2-4 versus median of 2 with IQR = 1-3; p = 0.009), and RA patients had more pregnancies than controls (p = 0.0002).

CONCLUSION

 The present study shows that, in our population, the duration of reproductive years and the number of pregnancies are linked to the onset of RA.

The Emerging Roles of Endocrine Hormones in Different Arthritic Disorders

The relationship between endocrine hormones and the spectrum of rheumatic conditions has long been discussed in the literature, focusing primarily on sexual hormones, such as estrogens, androgens, prolactin (PRL). Estrogens are indeed involved in the pathogenesis of the main inflammatory arthritis thanks to their effects on the immune system, both stimulatory and inhibitory. The PRL system has been discovered in synovial tissue of rheumatoid arthritis (RA) and psoriatic arthritis (PsA), patients and has been propose as a new potential therapeutic target. Besides sexual hormones, in the last years scientific interest about the crosstalk of immune system with other class of hormones has grown. Hormones acting on the bone tissue (i.e. parathyroid hormone, vitamin D) and modulators of the Wnt pathway (i.e. Dickkopf-1) have been demonstrated to play active role in inflammatory arthritis course, defining a new field of research named osteoimmunology. PTH, which is one of the main determinants of Dkkopf-1, plays a crucial role in bone erosions in RA and a correlation between PTH, Trabecular Bone Score (TBS) and disease activity has been found in ankylosing spondylitis (AS). In PSA is under studying the interaction among IL-17 and bone metabolism. The purpose of this review is to discuss and summarize the recent data about the interaction between endocrine hormone and immune system in the main rheumatic disorders, covering in particular the role of bone-related hormones and cytokines. We will describe this relationship from a biochemical, diagnostic and therapeutic perspective, with a particular focus on RA, PsA and AS.

Radiographically Occult Manifestation of Rheumatoid Arthritis in a Patient With Prolonged Clinical and Laboratory Evidence of Rampant Disease: A Case Report

Objective

The purpose of this case report is to present a case of rampant rheumatoid synovitis and arthritis of a patient with a long duration of symptoms and no radiographic abnormalities of rheumatoid arthritis at the initial diagnosis.

Clinical Features

A 49-year-old Hispanic woman presented to a chiropractic teaching clinic with an 8-month history of bilateral, symmetrical hand pain and stiffness noted specifically in her second and third metacarpophalangeal joints. The patient has reported no other health changes and no history of rheumatoid arthritis in the family.

Intervention and Outcome

Based on this patient's complaint, initial bilateral 3-view radiographic examination of the hands using computed radiography was performed. Despite prolonged history of inflammatory joint pain and rheumatoid arthritis confirmed by abnormally high levels of rheumatoid factor, C-reactive protein, and anti-cyclic citrulline peptide antibodies, the patient had no radiographic evidence of rheumatoid arthritis during the initial and repeat radiographic studies.

Conclusion

Some patients with rheumatoid arthritis may present with rampant clinical and laboratory abnormalities despite an apparent lack of radiographically detectable rheumatoid arthritis. This case demonstrates that astute clinicians should primarily rely on the results of clinical and laboratory abnormalities of rheumatoid arthritis and not be deterred or mislead by an apparent lack of radiographic changes at diagnosis. If the diagnosis of rheumatoid arthritis requires diagnostic imaging confirmation, then magnetic resonance imaging or diagnostic ultrasound of the hands should be used, especially if the initial radiographic assessment remains unrewarding.

Menopausal factors and risk of seropositive rheumatoid arthritis in postmenopausal women: a nationwide cohort study of 1.36 million women

In previous literature regarding development of rheumatoid arthritis (RA), female reproductive factors have been described as protective factors, risk factors, or irrelevant, leading to inconsistent results. The aim of this study was to investigate the effect of female reproductive factors on the incidence of seropositive RA. A large population-based retrospective cohort of the National Health Insurance Service data in South Korea was used. Postmenopausal women who participated in both cardiovascular and breast cancer screening in 2009 were included and followed until date of seropositive RA diagnosis, death, or December 31, 2018. Multivariable-adjusted Cox proportional hazards model was used to assess the association between reproductive factors and incident seropositive RA. Of 1,357,736 postmenopausal women, 6056 women were diagnosed with seropositive RA, and the incidence rate was 54.16 cases/100,000 person-years. Reproductive factors other than hormone replacement therapy (HRT) were not significantly associated with seropositive RA incidence. Postmenopausal women who used HRT ≥ 5 years were associated with a higher aHR of incident seropositive RA than never-users (aHR 1.25; 95% CI 1.09–1.44). Alcohol consumption less than 30 g per day (aHR 0.80; 95% CI 0.74–0.87), regular physical activity (aHR 0.90; 95% CI 0.84–0.97), diabetes mellitus (aHR 0.85; 95% CI 0.78–0.93), and cancer (aHR 0.77; 95% CI 0.64–0.92) were associated with lower risk of seropositive RA. Most female reproductive factors did not significantly affect the development of seropositive RA in postmenopausal women. Only HRT is associated with a small but significant increase in risk of seropositive RA.

Environment and Lifestyle: Their Influence on the Risk of RA

Background: Rheumatoid arthritis (RA) is a complex disease in which environmental agents are thought to interact with genetic factors that lead to triggering of autoimmunity. Methods: We reviewed environmental, hormonal, and dietary factors that have been suggested to be associated with the risk of RA. Results: Smoking is the most robust factor associated with the risk of RA, with a clear gene–environment interaction. Among other inhalants, silica may increase the risk of RA in men. There is less evidence for pesticides, pollution, and other occupational inhalants. Regarding female hormonal exposures, there is some epidemiological evidence, although not consistent in the literature, to suggest a link between hormonal factors and the risk of RA. Regarding dietary factors, available evidence is conflicting. A high consumption of coffee seems to be associated with an increased risk of RA, whereas a moderate consumption of alcohol is inversely associated with the risk of RA, and there is less evidence regarding other food groups. Dietary pattern analyses (Mediterranean diet, the inflammatory potential of the diet, or diet quality) suggested a potential benefit of dietary modifications for individuals at high risk of RA. Conclusion: To date, smoking and silica exposure have been reproducibly demonstrated to trigger the emergence of RA. However, many other environmental factors have been studied, mostly with a case-control design. Results were conflicting and studies rarely considered potential gene–environment interactions. There is a need for large scale prospective studies and studies in predisposed individuals to better understand and prevent the disease and its course.

Modulatory Effects of Pregnancy on Inflammatory Bowel Disease

The disease course of autoimmune diseases such as rheumatoid arthritis is altered during pregnancy, and a similar modulatory role of pregnancy on inflammatory bowel disease (IBD) has been proposed. Hormonal, immunological, and microbial changes occurring during normal pregnancy may interact with the pathophysiology of IBD. IBD consists of Crohn's disease and ulcerative colitis, and because of genetic, immunological, and microbial differences between these disease entities, they may react differently during pregnancy and should be described separately. This review will address the pregnancy-induced physiological changes and their potential effect on the disease course of ulcerative colitis and Crohn's disease, with emphasis on the modulation of epithelial barrier function and immune profiles by pregnancy hormones, microbial changes, and microchimerism.

Risk of breast cancer before and after rheumatoid arthritis, and the impact of hormonal factors

Objectives

To examine the risk of incident breast cancer in women with rheumatoid arthritis (RA), and the risk of RA in women with a history of breast cancer, taking antihormonal treatment for breast cancer into account.

Methods

Using nationwide Swedish registers, women with new-onset RA diagnosed in 2006–2016 were identified and analysed using a cohort and a case–control design. Each patient with RA was matched on age, sex and place of residence to five randomly selected subjects from the general population. Through register linkages, we collected information on breast cancer, breast cancer risk factors (reproductive history and hormone replacement therapy) and socio-economy. The relative risk of breast cancer after RA was assessed using Cox regression, and the relative risk of RA in women with a history of breast cancer was assessed using conditional logistic regression.

Results

The risk of incident breast cancer in women with RA was reduced and the association was not attenuated by adjustment for breast cancer risk factors (HR=0.80, 95% CI 0.68 to 0.93). The risk of RA in women with a history of breast cancer was similarly reduced (OR=0.87, 95% CI 0.79 to 0.95). Women with breast cancer treated with tamoxifen (OR=0.86, 95% CI 0.62 to 1.20) or aromatase inhibitors (OR=0.97, 95% CI 0.69 to 1.37) did not have an increased risk of RA compared with women with breast cancer treated differently.

Conclusions

The decreased occurrence of breast cancer in patients with RA is present already before RA diagnosis; these reduced risks are not readily explained by hormonal risk factors. Adjuvant antihormonal therapy for breast cancer does not seem to increase RA risk.

Immunogenicity of a rheumatoid arthritis protective sequence when acquired through microchimerism

HLA class II genes provide the strongest genetic contribution to rheumatoid arthritis (RA). HLA-DRB1 alleles encoding the sequence DERAA are RA-protective. Paradoxically, RA risk is increased in women with DERAA⁺ children born prior to onset. We developed a sensitive qPCR assay specific for DERAA, and found 53% of DERAA^-/- women with RA had microchimerism (Mc; pregnancy-derived allogeneic cells) carrying DERAA (DERAA-Mc) vs. 6% of healthy women. DERAA-Mc quantities correlated with an RA-risk genetic background including DERAA-binding HLA-DQ alleles, early RA onset, and aspects of RA severity. CD4⁺ T cells showed stronger response against DERAA⁺ vs. DERAA^- allogeneic cell lines in vitro, in line with an immunogenic role of allogeneic DERAA. Results indicate a model where DERAA-Mc activates DERAA-directed T cells that are naturally present in DERAA^-/- individuals and can have cross-reactivity against joint antigens. Moreover, we provide an explanation for the enigmatic observation that the same HLA sequence differentially affects RA risk through Mendelian inheritance vs. microchimeric cell acquisition.

Disease progression in relation to pre-onset parity among women with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) often ameliorates during pregnancy and flares postpartum, but the relationship of pregnancy and childbirth to RA prognosis is unclear. We examined RA severity for association with parity prior to RA onset and asked whether time from birth (latency) and/or the mother's HLA genotype influenced results.

METHODS

A cohort study was conducted of 222 women previously identified in a prospective study of newly diagnosed RA, who returned for follow-up evaluation a median of 8 years later. Stratified analyses using Mantel-Haenszel methods were conducted to evaluate 5 RA severity measures based on hand and wrist radiographs, physical exams, and Health Assessment Questionnaires for association with parity.

RESULTS

Overall, we observed little evidence of altered risk of progression to severe RA in relation to pre-onset parity, adjusting for RA onset age and time to follow-up. Stratifying parous women who had only live births by latency (<15 years/15+ years) showed no difference in risk of severe RA compared to nulligravid women. Live birth deliveries were significantly protective for women with 0 but not for those with 1 or 2 copies of the RA risk-associated HLA-DRB1 shared epitope sequence for erosion score (RR 0.26 95% CI 0.09-0.89) and joint count (RR 0.28 95% CI 0.09-0.87).

CONCLUSION

We observed little evidence of difference in severe RA by pre-onset parity overall. However, among women not predisposed to RA by possessing the risk-associated HLA genotype, parous women who had only live births had lower risk of progression to severe RA as measured by erosion score and joint count.

Feto-Maternal Microchimerism: The Pre-eclampsia Conundrum

Feto-maternal microchimerism (FMM) involves bidirectional cross-placental trafficking during pregnancy, leading to a micro-chimeric state that can persist for decades. In this manner a pregnant woman will harbor cells from her mother, as well as, cells from her child. Historically, eclampsia, a severe disorder of pregnancy provided the basis for FMM following the detection of trophoblast cells in the lungs of deceased women. Bi-directional cell trafficking between mother and fetus is also altered in pre-eclampsia and has been suggested to contribute to the underlying etiology. FMM has been implicated in tolerance promotion, remission of auto-inflammatory disorders during pregnancy, or the development of autoimmune conditions post-partum. The underlying mechanism whereby the host immune system is modulated is unclear but appears to involve HLA class II molecules, in that incompatibility between mother and fetus promotes remission of rheumatoid arthritis, whereas feto-maternal HLA compatibility may assist in the post-partum initiation of scleroderma. Couples having a high degree of HLA class II compatibility have an increased risk for pre-eclampsia, while the occurrence of scleroderma and rheumatoid arthritis is greater in pre-eclamptic cases than in women with normal pregnancies, suggesting a long term autoimmune predisposition. Since pregnant women with pre-eclampsia exhibit significantly lower levels of maternally-derived micro-chimerism, the question arises whether pre-eclampsia and post-partum development of autoimmune conditions occur due to the failure of the grandmothers cells to adequately regulate an inappropriate micro-chimeric constellation.

Specific Donor HLA-DR Types Correlate With Altered Susceptibility to Development of Chronic Lung Allograft Dysfunction

BACKGROUND

The greatest challenge to long-term graft survival is the development of chronic lung allograft dysfunction. Th17 responses to collagen type V (colV) predispose lung transplant patients to the severe obstructive form of chronic lung allograft dysfunction, known as bronchiolitis obliterans syndrome (BOS). In a previous study cohort (n = 54), pretransplant colV responses were increased in recipients expressing HLA-DR15, consistent with the high binding avidity of colV (α1) peptides for HLA-DR15, whereas BOS incidence, which was known to be strongly associated with posttransplant autoimmunity to colV, was higher in patients who themselves lacked HLA-DR15, but whose lung donor expressed it.

METHODS

To determine if this DR-restricted effect on BOS incidence could be validated in a larger cohort, we performed a retrospective analysis of outcomes for 351 lung transplant recipients transplanted between 1988 and 2008 at the University of Wisconsin. All subjects were followed until graft loss, death, loss to follow-up, or through 2014, with an average follow-up of 7 years. Comparisons were made between recipients who did or did not develop BOS. Grading of BOS followed the recommendations of the international society for heart and lung transplantation.

RESULTS

Donor HLA-DR15 was indeed associated with increased susceptibility to severe BOS in this population. We also discovered that HLA-DR7 expression by the donor or HLA-DR17 expression by the recipient decreased susceptibility.

CONCLUSIONS

We show in this retrospective study that specific donor HLA class II types are important in lung transplantation, because they are associated with either protection from or susceptibility to development of severe BOS.

Fetal microchimerism by mode of delivery: a prospective cohort study

OBJECTIVE

To compare fetal microchimerism (FMc) in pregnancies with uncomplicated vaginal delivery (VD) versus caesarean delivery (CD).

DESIGN

Prospective cohort study.

SETTING

University of Washington and Fred Hutchinson Cancer Research Center, USA.

POPULATION

Women delivering singleton pregnancies without pertinent antenatal complications with uncomplicated deliveries (n = 36).

METHODS

We collected maternal predelivery, postdelivery and umbilical cord blood for each mother-baby pair. Following maternal and fetal genotyping, FMc was measured with quantitative polymerase chain reaction assays targeting fetus-specific polymorphisms. Quantification of FMc is expressed as genome equivalents (gEq) of fetal DNA/100 000 total gEq tested. FMc detection was evaluated by logistic regression while controlling for total number of cell equivalents tested and clinically relevant covariates. FMc concentrations were compared using negative binomial regression while controlling for the same covariates and predelivery FMc positivity.

MAIN OUTCOME MEASURE

Detection and concentration of FMc by mode of delivery.

RESULTS

Twenty-four mother-baby pairs had a VD and 12 had a CD. Postdelivery FMc detection was higher following CD than after VD (58.3% versus 16.7%, P = 0.02). After controlling for covariates, the likelihood of postdelivery FMc detection was almost nine-fold higher after CD than VD (odds ratio 8.8, 95% CI 1.6-47.6; P = 0.01). With respect to postdelivery FMc concentration, the detection rate ratio for CD versus VD in the adjusted negative binomial regression model was 14.7 (95% CI 3.2-66.8; P = 0.001).

CONCLUSION

Postdelivery peripheral FMc detection and concentration are significantly higher after CD than after VD. As FMc is associated with long-term maternal health, our findings suggest that the mode of delivery may impact this risk.

TWEETABLE ABSTRACT

Greater fetal microchimerism found in maternal blood following caesarean delivery compared with vaginal delivery.

Parity and HLA alleles in risk of rheumatoid arthritis

Specific HLA II alleles are associated with rheumatoid arthritis (RA) risk and others with protection. Risk-associated alleles encode similar amino acid sequences from 70 through 74 of HLA-DRβ1 (QKRAA, QRRAA, RRRAA), referred to as the "shared epitope" (SE) and protective alleles encode DERAA at the same location. Fetal-maternal cell exchange results in long-term microchimerism i.e. harboring small numbers of genetically disparate cells. Women with RA who lack the SE were recently found to harbor microchimerism with the SE more often than healthy women. This finding raises the question whether microchimerism with DERAA confers benefit against RA and is underscored by the observation that overall parity reduces RA risk. While there is currently no test for microchimerism with DERAA, we conducted studies to ask whether parity benefits women at risk for RA, either because they have the SE or lack the protective DERAA sequence. HLA genotyping was conducted for 310 RA and 571 healthy women. Parity was associated with reduced RA risk in women aged <45 years (RR 0.53, 95% CI 0.34-0.82) and further analyses examined this group. RA risk reduction with parity was greater among women with the SE than SE-negative women (RR 0.42, 95%CI 0.22-0.79 vs. RR 0.79, 0.38-1.64). Among women without DERAA, RA risk was significantly reduced with parity (RR 0.44, 95% CI 0.26-0.74) but not among DERAA-positive women (RR 0.95 95% CI 0.34-2.65). In summary, results indicate the effect of parity varied according to a woman's HLA-genotype, and women at increased risk of RA benefited most.

Immunological implications of pregnancy-induced microchimerism

Immunological identity is traditionally defined by genetically encoded antigens, with equal maternal and paternal contributions as a result of Mendelian inheritance. However, vertically transferred maternal cells also persist in individuals at very low levels throughout postnatal development. Reciprocally, mothers are seeded during pregnancy with genetically foreign fetal cells that persist long after parturition. Recent findings suggest that these microchimeric cells expressing non-inherited, familially relevant antigenic traits are not accidental 'souvenirs' of pregnancy, but are purposefully retained within mothers and their offspring to promote genetic fitness by improving the outcome of future pregnancies. In this Review, we discuss the immunological implications, benefits and potential consequences of individuals being constitutively chimeric with a biologically active 'microchiome' of genetically foreign cells.

Rheumatoid arthritis: Forward and reverse inheritance - the yin and the yang

The theory of Mendelian inheritance states that half our genes are maternal and half are paternal. This view is incomplete, as maternal–fetal exchange creates a legacy of non-native cells within an individual that can affect their health for better or worse, including contributing to their risk of developing autoimmune disease.

Environmental factors and hormones in the development of rheumatoid arthritis

The etiopathogenesis of rheumatoid arthritis (RA) is partially understood. Genetic, environmental, and hormonal factors and their interactions are considered to play an important role on disease development. The relative contribution of environmental factors to RA development is probably larger than previously thought. The aim of this review is to appraise robust evidence about the role of environmental and hormonal risk factors for RA. We will discuss inhaled pollutants, nutritional habits, infectious, hormonal, and reproductive factors. As some of these factors are potentially modifiable, understanding their impact on RA development opens new opportunities for potential interventions and disease prevention.

Genetic and environmental risk factors for rheumatoid arthritis

Multiple genetic and environmental factors have been associated with an increased risk for rheumatoid arthritis (RA). Of these, the strongest associations have been seen with female sex, a family history of RA, the genetic factor the "shared epitope," and exposure to tobacco smoke. There is also renewed interest in mucosal inflammation and microbial factors as contributors to the development of RA. However, the identification of a "preclinical" period of RA that can be defined as local or systemic autoimmunity as measured by autoantibodies and other biomarkers prior to the development of clinically apparent synovitis suggests that the risk factors for RA are acting long prior to first clinical evidence of IA. As such, a major challenge to the field will be to investigate the full spectrum of the development of RA, from initiation and propagation of autoimmunity during preclinical RA and transition to clinically apparent synovitis and classifiable RA, to determine which genetic and environmental factors are important at each stage of disease development. Understanding the exact role and timing of action of risk factors for RA is especially important given the advent of prevention trials in RA, and the hope that a full understanding of genetic and environmental factors in RA could lead to effective preventive interventions.

Pregnancy and autoimmune connective tissue diseases

Autoimmune connective tissue diseases predominantly affect women and often occur during the reproductive years. Thus, specialized issues in pregnancy planning and management are commonly encountered in this patient population. This chapter provides a current overview of pregnancy as a risk factor for onset of autoimmune disease, considerations related to the course of pregnancy in several autoimmune connective tissue diseases, and disease management and medication issues before pregnancy, during pregnancy, and in the postpartum period. A major theme that has emerged across these inflammatory diseases is that active maternal disease during pregnancy is associated with adverse pregnancy outcomes, and that maternal and fetal health can be optimized when conception is planned during times of inactive disease and through maintaining treatment regimens compatible with pregnancy.

Pregnancy-Induced Changes in Systemic Gene Expression among Healthy Women and Women with Rheumatoid Arthritis

Background

Pregnancy induces drastic biological changes systemically, and has a beneficial effect on some autoimmune conditions such as rheumatoid arthritis (RA). However, specific systemic changes that occur as a result of pregnancy have not been thoroughly examined in healthy women or women with RA. The goal of this study was to identify genes with expression patterns associated with pregnancy, compared to pre-pregnancy as baseline and determine whether those associations are modified by presence of RA.

Results

In our RNA sequencing (RNA-seq) dataset from 5 healthy women and 20 women with RA, normalized expression levels of 4,710 genes were significantly associated with pregnancy status (pre-pregnancy, first, second and third trimesters) over time, irrespective of presence of RA (False Discovery Rate (FDR)-adjusted p value<0.05). These genes were enriched in pathways spanning multiple systems, as would be expected during pregnancy. A subset of these genes (n = 256) showed greater than two-fold change in expression during pregnancy compared to baseline levels, with distinct temporal trends through pregnancy. Another 98 genes involved in various biological processes including immune regulation exhibited expression patterns that were differentially associated with pregnancy in the presence or absence of RA.

Conclusions

Our findings support the hypothesis that the maternal immune system plays an active role during pregnancy, and also provide insight into other systemic changes that occur in the maternal transcriptome during pregnancy compared to the pre-pregnancy state. Only a small proportion of genes modulated by pregnancy were influenced by presence of RA in our data.

Parity influences the severity of ACPA-negative early rheumatoid arthritis: a cohort study based on the Swedish EIRA material

BACKGROUND

In women with rheumatoid arthritis (RA) it has been observed that during pregnancy a majority of patients experience amelioration, but after delivery a relapse of the disease is common. However, there are few studies, with diverging results, addressing the effect of parity on the severity of RA over time. Our aim was to explore the impact of parity, with stratification for anti-citrullinated protein antibody (ACPA) status as well as for onset during reproductive age or not.

METHODS

Female RA cases aged 18-70 years were recruited for the Epidemiological Investigation of Rheumatoid Arthritis (EIRA). Information on disease severity (the health assessment questionnaire (HAQ) and the disease activity score 28 (DAS28)) was retrieved from the Swedish Rheumatology Quality Register at inclusion and 3, 6, 12 and 24 months after diagnosis. Mixed models were used to compare mean DAS28 and HAQ scores over time in parous and nulliparous women. Mean differences at individual follow-up visits were compared using analysis of covariance. The odds of having DAS28 or HAQ above the median in parous verus nulliparous women were estimated in logistic regression models.

RESULTS

A total of 1237 female cases (mean age 51 years, 65 % ACPA-positive) were included. ACPA-negative parous women, aged 18-44 years, had on average 1.17 units higher DAS28 (p < 0.001) and 0.43 units higher HAQ score (p < 0.001) compared to nulliparous women during the follow-up time, adjusted for age. In this subgroup, the average DAS28 and HAQ scores were significantly higher in parous women at all follow-up time points. Younger parous ACPA-negative women were significantly more likely to have DAS28 and HAQ values above the median compared to nulliparous women at all follow-up visits. No association between parity and severity of ACPA-positive disease was observed.

CONCLUSIONS

Parity was a predictor of a more severe RA among ACPA-negative younger women, which might indicate that immunomodulatory changes during and after pregnancy affect RA severity, in particular for the ACPA-negative RA phenotype.

Postmenopausal hormone therapy and the risk of rheumatoid arthritis: results from the Swedish EIRA population-based case-control study

To study the association between postmenopausal hormone therapy (PMH) use and the risk of rheumatoid arthritis (RA) stratifying the cases by the presence/absence of antibodies against citrullinated peptides (ACPA). A subset of the Epidemiological Investigation of RA (EIRA), a population-based case-control study, comprising postmenopausal women aged 50–70 living in Sweden, between 2006 and 2011 was analysed (523 cases and 1057 controls). All participants answered an extensive questionnaire, including questions regarding PMH use and potential confounders (education, smoking, BMI, oral contraceptives, reproductive factors). We calculated odds ratios (OR) of developing ACPA-positive/-negative RA, with 95 % confidence intervals (CI) and adjusted for age, residential area and smoking. Current users of PMH had a decreased risk of ACPA-positive RA compared with never users (OR 0.6, 95 % CI 0.3–0.9). The decreased risk was observed mainly in the age-group 50–59 years (OR 0.3, 95 % CI 0.1–0.8) but not in the age-group 60–70 years (OR 0.8, 95 % CI 0.4–1.4). Among current users of a combined therapy (estrogen plus progestogens) an OR of 0.3 (95 % CI 0.1–0.7) of ACPA-positive RA was observed, while no significant association was found among women who used estrogen only (OR 0.8, 95 % CI 0.5–1.6). No association between PMH use and ACPA-negative RA was found. PMH use might reduce the risk of ACPA-positive RA in post-menopausal women over 50 years of age, but not of ACPA-negative RA. The negative influence of this treatment on the risk of other chronic conditions cannot be overlooked.

Adverse pregnancy outcomes and risk of subsequent rheumatoid arthritis

OBJECTIVE

Pregnancy and reproductive outcomes have been associated with altered risk of some autoimmune diseases, including rheumatoid arthritis (RA). We sought to determine whether prior pregnancy resulting in a low birth weight (LBW) infant or preterm birth is associated with a risk of subsequent RA in the mother.

METHODS

We conducted an analysis of RA risk in parous women from a population-based prospective study of newly diagnosed cases of RA and age-matched healthy controls. The primary outcome measure was disease status (RA versus control), with exposures of prior preterm birth and prior delivery of an infant with LBW (≤2,500 gm), very low birth weight (VLBW; ≤1,500 gm), or extremely low birth weight (ELBW; ≤1,000 gm). A preplanned analysis including only rheumatoid factor (RF)-positive RA cases was also conducted.

RESULTS

A total of 202 RA cases and 1,102 controls were analyzed. Prior delivery of an infant with ELBW was associated with RA in the mother (relative risk [RR] 3.7 [95% confidence interval (95% CI) 1.0-13.2]). Prior VLBW (RR 4.0 [95% CI 1.3-11.4]) and ELBW (RR 5.5 [95% CI 1.4-22.5]) infants were associated with RF-positive RA. Prior LBW deliveries and preterm births were more common among RA cases than controls, but the differences were not statistically significant.

CONCLUSION

Compared to those with uncomplicated pregnancies, women with a prior VLBW or ELBW delivery had a higher risk of RA, particularly RF-positive RA. This association may reflect common risk factors for pregnancy complications and RA. Alternatively, complicated pregnancy itself may confer risk of subsequent RA.

Is pregnancy a risk factor for rheumatic autoimmune diseases?

PURPOSE OF REVIEW

To review the association of pregnancy with the risk of subsequent development of rheumatic autoimmune diseases in women, including rheumatoid arthritis (RA), systemic lupus erythematosus, and scleroderma.

RECENT FINDINGS

There is a small but growing literature related to the risk of autoimmune rheumatic disease in association with pregnancy history. However, results conflict both in terms of the direction and magnitude of risk of disease in relationship to prior pregnancy history. Although anecdotal evidence tends to favor the premise that pregnancy is protective against certain diseases, such as RA, the heterogeneity of results precludes the ability to confirm an association in either direction. There is indication that time elapsed since pregnancy may influence risk, with the postpartum year being of particular relevance.

SUMMARY

To date, a clear pattern has not emerged regarding pregnancy and the future risk of autoimmune rheumatic diseases. This topic requires greater study, and given the strong female preponderance of these diseases, future research efforts should seek to resolve this important issue.

Long-term persistence and effects of fetal microchimerisms on disease onset and status in a cohort of women with rheumatoid arthritis and systemic lupus erythematosus

Background

The discovery of a fetal cells transfer to the mother is a phenomenon with multiple implications for autoimmunity and tolerance. The prevalence and meaning of the feto-maternal microchimerism (MC) in rheumatic diseases has not been thoroughly investigated. The aim of this study was to analyze the prevalence of fetal MC in patients with inflammatory rheumatic diseases and to investigate the association of MC with disease onset and current status.

Methods

A total of 142 women who gave birth to at least one male offspring were recruited: 72 women with rheumatoid arthritis (RA), 16 women with systemic lupus erythematosus (SLE), and 54 healthy women. For the detection of fetal microchimerism a nested PCR method was used to amplify a Y chromosome specific sequence (TSPY1). For characterization of disease activity we analyzed autoantibody profiles and X-rays in RA, and in addition complement levels in SLE respectively.

Results

A significant higher prevalence of fetal MC was found in RA (18%) and SLE (31%) compared to controls (3.7%) (p = 0.02 and p = 0.006, resp.). The mean age at disease onset was comparable in MC + and MC- RA patients. Disease onset occurred 18.7 (MC +) and 19.8 (MC-) years post partum of the first son, respectively. The presence of anti-CCP and RF did not differ significantly, anti-CCP were found in 75% of MC + and 87% of MC- patients, RF in 75% of both MC + and MC- patients. A slightly higher mean Steinbrocker score in MC + patients was associated with longer disease duration in MC + compared to MC- RA. In SLE patients the mean age at disease onset was 42.6 years in MC + and 49.1 years in MC- patients. Disease onset occurred 24.0 and 26.4 years post partum of the first son for MC + and MC- patients, respectively. The presence of ANA and anti-dsDNA antibodies, C3, C4 and CH50 did not differ significantly.

Conclusion

Our results indicate a higher frequency of long-term male MC in RA and SLE patients compared with controls without impact on disease onset and status in RA and SLE.

Predicting the risk of rheumatoid arthritis and its age of onset through modelling genetic risk variants with smoking

The improved characterisation of risk factors for rheumatoid arthritis (RA) suggests they could be combined to identify individuals at increased disease risks in whom preventive strategies may be evaluated. We aimed to develop an RA prediction model capable of generating clinically relevant predictive data and to determine if it better predicted younger onset RA (YORA). Our novel modelling approach combined odds ratios for 15 four-digit/10 two-digit HLA-DRB1 alleles, 31 single nucleotide polymorphisms (SNPs) and ever-smoking status in males to determine risk using computer simulation and confidence interval based risk categorisation. Only males were evaluated in our models incorporating smoking as ever-smoking is a significant risk factor for RA in men but not women. We developed multiple models to evaluate each risk factor's impact on prediction. Each model's ability to discriminate anti-citrullinated protein antibody (ACPA)-positive RA from controls was evaluated in two cohorts: Wellcome Trust Case Control Consortium (WTCCC: 1,516 cases; 1,647 controls); UK RA Genetics Group Consortium (UKRAGG: 2,623 cases; 1,500 controls). HLA and smoking provided strongest prediction with good discrimination evidenced by an HLA-smoking model area under the curve (AUC) value of 0.813 in both WTCCC and UKRAGG. SNPs provided minimal prediction (AUC 0.660 WTCCC/0.617 UKRAGG). Whilst high individual risks were identified, with some cases having estimated lifetime risks of 86%, only a minority overall had substantially increased odds for RA. High risks from the HLA model were associated with YORA (P<0.0001); ever-smoking associated with older onset disease. This latter finding suggests smoking's impact on RA risk manifests later in life. Our modelling demonstrates that combining risk factors provides clinically informative RA prediction; additionally HLA and smoking status can be used to predict the risk of younger and older onset RA, respectively.

Rheumatoid arthritis (RA) is a common, incurable disease with major individual and health service costs. Preventing its development is therefore an important goal. Being able to predict who will develop RA would allow researchers to look at ways to prevent it. Many factors have been found that increase someone's risk of RA. These are divided into genetic and environmental (such as smoking) factors. The risk of RA associated with each factor has previously been reported. Here, we demonstrate a method that combines these risk factors in a process called “prediction modelling” to estimate someone's lifetime risk of RA. We show that firstly, our prediction models can identify people with very high-risks of RA and secondly, they can be used to identify people at risk of developing RA at a younger age. Although these findings are an important first step towards preventing RA, as only a minority of people tested had substantially increased disease risks our models could not be used to screen the general population. Instead they need testing in people already at risk of RA such as relatives of affected patients. In this context they could identify enough numbers of high-risk people to allow preventive methods to be evaluated.

Parity and the risk of developing rheumatoid arthritis: results from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study

OBJECTIVE

To study the impact of parity history on the risk of antibodies to citrullinated peptide antigens (ACPA) positive and ACPA-negative rheumatoid arthritis (RA), in different age-groups.

METHOD

Data from a population-based case-control study of female incident RA cases were analysed (2035 cases and 2911 controls, aged 18-70 years ). Parity history was assessed through a questionnaire. Parous women were compared with nulliparous, by calculating odds ratios (ORs) with 95% confidence interval (CI).

RESULTS

Parity was associated with an increased risk of ACPA-negative RA in women aged 18-44 years (OR=2.1, 95% CI 1.4 to 3.2), but not in those aged 45-70 years (OR=0.9, 95% CI 0.7 to 1.3). Among young women, an increased risk of ACPA-negative RA was found in those who gave birth during the year of symptom onset (OR=2.6, 95% CI 1.4 to 4.8) and who were at a young age at first birth (<23) (OR=2.5, 95% CI 1.5 to 4.1). Parity and the postpartum period were not associated with ACPA-positive RA, but older age at first birth was weakly associated with a decreased risk.

CONCLUSIONS

The increased risk of ACPA-negative RA in parous women of reproductive age seemed to be associated with an increased postpartum risk and with young age at first birth. Further research is needed to explore the biological mechanisms behind our findings.

Using lifestyle factors to identify individuals at higher risk of inflammatory polyarthritis (results from the European Prospective Investigation of Cancer-Norfolk and the Norfolk Arthritis Register--the EPIC-2-NOAR Study)

Objectives

To investigate the association of lifestyle factors with risk of inflammatory polyarthritis (IP) and rheumatoid arthritis (RA).

Methods

The European Prospective Investigation of Cancer, Norfolk, UK (EPIC-Norfolk) gathered lifestyle data from participants aged 40–79 years from 1993 to 1997. Individuals who subsequently developed IP were identified by linkage with the Norfolk Arthritis Register. A Cox proportional hazard model was developed, and a score assigned to each risk factor to calculate the odds of developing IP.

Results

25 455 EPIC participants were followed for a median (IQR) of 14.2 (12.9, 15.3) years; 184 developed incident IP (138 cumulatively fulfilled criteria for RA; 107 were seropositive). Pack-years of smoking were associated with increased risk of IP and RA in men (HR 1.21 (95% CI 1.08 to 1.37) per 10-pack-years) and seropositive IP (HR 1.24 (95% CI 1.10 to 1.41)) for all. Diabetes mellitus was associated with increased risk of IP (HR 2.54 (95% CI 1.26 to 5.09)), while alcohol (HR 0.86 (95% CI 0.74 to 0.99) per unit/day) and higher social class (HR 0.36 (95% CI 0.15 to 0.89) for professionals vs manual workers) were associated with reduced risk. Body mass index was associated with seronegative IP (HR 2.75 (95% CI 1.39 to 5.46) for obese vs normal-weight participants). In women, parity (HR 2.81 (95% CI 1.37 to 5.76) for ≥2 vs no children) was associated with increased risk, and breast feeding (HR 0.66 (95% CI 0.46 to 0.94) for every 52 weeks of breast feeding) was inversely associated with risk. Risk factors from the model were used to generate a ‘risk score’. A total of 1159 (8.4%) women had scores reflecting a >3-fold increased risk of IP over those with a score of 0.

Conclusions

Several easily ascertained clinical and lifestyle factors can be used to stratify populations for risk of IP.

Acquisition of the rheumatoid arthritis HLA shared epitope through microchimerism

OBJECTIVE

HLA-DRB1 alleles associated with risk of rheumatoid arthritis (RA) encode similar HLA-DRB1 sequences, called the shared epitope (SE). The most common SE sequences are QKRAA and QRRAA. Nevertheless, a substantial number of RA patients lack the SE. Bidirectional fetal-maternal trafficking results in long-term persistence of fetal cells in the mother and maternal cells in her offspring, a process known as microchimerism. This study was undertaken to discover whether RA patients who lack the SE can acquire it through microchimerism.

METHODS

We studied a total of 86 female subjects who were genotypically negative for the SE, comprising 52 patients with RA and 34 healthy controls. We developed specific real-time quantitative polymerase chain reaction assays for the SE-encoded sequences QKRAA and QRRAA, and used them to test DNA extracted from peripheral blood mononuclear cells.

RESULTS

Microchimerism with the SE was found significantly more often in RA patients than controls (odds ratio 4.1 [95% confidence interval 1.6-10.0], P = 0.003). Concentrations of SE microchimerism were also significantly higher among RA patients than controls (P = 0.002). In separate analyses for SE type, the prevalence of QKRAA microchimerism in RA patients versus healthy controls was 17% versus 3% (9 of 52 versus 1 of 34; P = 0.03) and the prevalence of QRRAA microchimerism was 40% versus 18% (21 of 52 versus 6 of 34; P = 0.04), respectively. Microchimerism concentrations were also higher in RA patients than healthy subjects for QKRAA (P = 0.03) and QRRAA (P = 0.03).

CONCLUSION

These results indicate that RA patients who genotypically lack the SE can acquire the SE as persistent microchimerism from fetal-maternal cell exchange, suggesting that SE-encoding microchimerism could be a risk factor for RA.

Microchimerism in the rheumatoid nodules of patients with rheumatoid arthritis

OBJECTIVE

The rheumatoid nodule is a lesion commonly found on extraarticular areas prone to mechanic trauma. When present with inflammatory symmetric polyarthritis, it is pathognomonic of rheumatoid arthritis (RA), an autoimmune disease in which naturally acquired microchimerism has previously been described and can sometimes contribute to RA risk. Since RA patients harbor microchimerism in the blood, we hypothesized that microchimerism is also present in rheumatoid nodules and could play a role in rheumatoid nodule formation. This study was undertaken to investigate rheumatoid nodules for microchimerism.

METHODS

Rheumatoid nodules were tested for microchimerism by real-time quantitative polymerase chain reaction (qPCR). The rheumatoid nodules of 29 female patients were tested for a Y chromosome-specific sequence. After HLA genotyping of patients and family members, rheumatoid nodules from 1 man and 14 women were tested by HLA-specific qPCR, targeting a nonshared HLA allele of the potential microchimerism source. Results were expressed as genome equivalents of microchimeric cells per 10(5) patient genome equivalents (GE/10(5)).

RESULTS

Rheumatoid nodules from 21% of the female patients contained male DNA (range <0.5, 10.3 GE/10(5)). By HLA-specific qPCR, 60% of patients were microchimeric (range 0, 18.5 GE/10(5)). Combined microchimerism prevalence was 47%. A fetal or maternal source was identified in all patients who tested positive by HLA-specific qPCR. Unexpectedly, a few rheumatoid nodules also contained microchimerism without evidence of a fetal or maternal source, suggesting alternative sources.

CONCLUSION

Our findings indicate that microchimerism is frequently present in the rheumatoid nodules of RA patients. Since microchimerism is genetically disparate, whether microchimerism in rheumatoid nodules serves as an allogeneic stimulus or allogeneic target warrants further investigation.

Prospective assessment of fetal-maternal cell transfer in miscarriage and pregnancy termination

BACKGROUND

Fetal cells (microchimerism) are acquired by women during pregnancy. Fetal microchimerism persists decades later and includes cells with pluripotent capacity. Persistent microchimerism has the capacity for both beneficial and detrimental maternal health consequences. Both miscarriage and termination of pregnancy can result in fetal microchimerism. We sought to determine whether cellular fetal microchimerism is acquired during management of pregnancy loss and further explored factors that could influence fetal cell transfer, including viability of fetal tissue, surgical versus medical management and gestational age.

METHODS

Pregnant women (n= 150 samples from 75 women) with singleton pregnancies undergoing a TOP (n= 63) or treatment for embryonic or fetal demise (miscarriage, n= 12) were enrolled. Mononuclear cells were isolated from blood samples drawn before, and 30 min after, treatment. Fetal cellular microchimerism concentrations were determined using quantitative PCR for a Y chromosome-specific sequence, expressed as genome equivalents of fetal DNA per 100 000 maternal cell equivalents (gEq/10(5)). Detection rate ratios were determined according to clinical characteristics.

RESULTS

Cellular fetal microchimerism was found more often in post- compared with pretreatment samples, 24 versus 5% (P= 0.004) and at higher concentrations, 0-36 versus 0-0.7 gEq/10(5) (P< 0.001). Likelihood of microchimerism was higher in surgical than medical management, detection rate ratio 24.7 (P= 0.02). The detection rate ratio for TOP versus miscarriage was 16.7 for known male fetuses (P= 0.02). Microchimerism did not vary with gestational age.

CONCLUSIONS

Significant fetal cell transfer occurs during miscarriage and TOP. Exploratory analyses support relationships between obstetric clinical factors and acquisition of fetal cellular microchimerism; however, our limited sample size precludes definitive analysis of these relationships, and confirmation is needed. In addition, the long-term persistence and potential consequences of fetal microchimerism on maternal health merit further investigation.

The otherness of self: microchimerism in health and disease

Microchimerism (Mc) refers to the harboring of a small number of cells (or DNA) that originated in a different individual. Naturally acquired Mc derives primarily from maternal cells in her progeny, or cells of fetal origin in women. Both maternal and fetal Mc are detected in hematopoietic cells including T and B cells, monocyte/macrophages, natural killer (NK) cells and granulocytes. Mc appears also to generate cells such as myocytes, hepatocytes, islet β cells and neurons. Here, the detrimental and beneficial potential of Mc is examined. The prevalence, diversity and durability of naturally acquired Mc, including in healthy individuals, indicates that a shift is needed from the conventional paradigm of 'self versus other' to a view of the normal 'self' as constitutively chimeric.

Progesterone and autoimmune disease

Sexual dimorphism in human immune systems is most apparent in the female predominance of certain autoimmune diseases (ADs) like systemic lupus erythematosus (SLE). Epidemiologic, observational and experimental evidence strongly suggest sex steroids are important modulators of genetic risk in human AD. In this regard, the roles of progesterone (Pg), an immunomodulatory female sex steroid, are poorly understood. Several lines of investigation indicate Pg and synthetic progestins impact risk of AD and immune-mediated injury in different ways depending on their concentrations and their engagement of various Pg receptors expressed in immune organs, immune cells or tissues targeted by immune attack. At low physiologic levels, Pg may enhance interferon-alpha (IFN-α) pathways important in SLE pathogenesis. Commonly used synthetic progestins may have the opposite effect. At pregnancy levels, Pg may suppress disease activity in rheumatoid arthritis (RA) and multiple sclerosis (MS) via inhibition of T helper type 1 (Th1) and Th17 pathways and induction of anti-inflammatory molecules. Importantly, Pg's immunomodulatory effects differ from those of estrogens and androgens. An additional layer of complexity arises from apparent interdependence of sex hormone signaling pathways. Identifying mechanisms by which Pg and other sex steroids modulate risk of AD and immune-mediated injury will require clarification of their cellular and molecular targets in vivo. These future studies should be informed by recent genetic discoveries in human AD, particularly those revealing their sex-specific genetic associations.

Modifiable risk factors for RA: prevention, better than cure?

Objective. To perform a meta-synthesis of the evidence for modifiable lifestyle risk factors for inflammatory polyarthritis (IP) and RA.

Methods. We performed a MEDLINE literature search. Case–control and cohort studies and systematic reviews published from 1948 through February 2011 and studying modifiable risk factors for RA were retrieved. The main outcome measure was diagnosis of RA according to the standard criteria.

Results. Smoking contributes up to 25% of the population burden of RA. The risk is dose related, stronger in males and especially strong for anti-citrullinated peptide antibody positive (ACPA⁺) RA through an interaction with the shared epitope. After smoking cessation, there is, however, a latency of up to 20 years to return to baseline risk. Other associations are less definitive; however, prospective studies suggest that dietary antioxidants and breastfeeding may be protective and that high coffee consumption may increase RA risk. An inverse association with alcohol intake (especially in smokers) and with education/social class (especially seropositive RA) and an increased risk with obesity (seronegative RA) is also noted.

Conclusion. There is a need for further large-scale prospective studies with a consistent definition of RA phenotype (undifferentiated IP through to ACPA⁺/RF⁺ disease). This will ultimately afford the opportunity to evaluate preventative population strategies for RA akin to the well-established programmes for cardiovascular disease and cancer, targeting common risk factors.

Rheumatoid arthritis and pregnancy: evolution of disease activity and pathophysiological considerations for drug use

It has long been known that pregnancy and childbirth have a profound effect on the disease activity of rheumatic diseases. For clinicians, the management of patients with RA wishing to become pregnant involves the challenge of keeping disease activity under control and adequately adapting drug therapy during pregnancy and post-partum. This article aims to summarize the current evidence on the evolution of RA disease activity during and after pregnancy and the use of anti-rheumatic drugs around this period. Of recent interest is the potential use of anti-TNF compounds in the preconception period and during pregnancy. Accumulating experience with anti-TNF therapy in other immune-mediated inflammatory diseases, such as Crohn's disease, provides useful insights for the use of TNF blockade in pregnant women with RA, or RA patients wishing to become pregnant.

Antigenic challenge in the etiology of autoimmune disease in women

Infection has long been implicated as a trigger for autoimmune disease. Other antigenic challenges include receipt of allogeneic tissue or blood resulting in immunomodulation. We investigated antigenic challenges as possible risk factors for autoimmune disease in women using the Health and Retirement Study, a nationally representative longitudinal study, linked to Medicare files, years 1991-2007. The prevalence of autoimmune disease (rheumatoid arthritis, Hashimoto's disease, Graves' disease, systemic lupus erythematosus, celiac disease, systemic sclerosis, Sjögren syndrome and multiple sclerosis) was 1.4% in older women (95% CI: 1.3%, 1.5%) with significant variation across regions of the United States. The risk of autoimmune disease increased by 41% (95% CI of incidence rate ratio (IRR): 1.10, 1.81) with a prior infection-related medical visit. The risk of autoimmune disease increased by 90% (95% CI of IRR: 1.36, 2.66) with a prior transfusion without infection. Parity was not associated with autoimmune disease. Women less than 65 years of age and Jewish women had significantly elevated risk of developing autoimmune disease, as did individuals with a history of heart disease or end-stage renal disease. Antigenic challenges, such as infection and allogeneic blood transfusion, are significant risk factors for the development of autoimmune disease in older women.

[Fetal microchimerism: self and non-self, finally who are we?]

For a long time, the conventional view was that the fetus and maternal vascular system are kept separate. In fact there is a two-way traffic of immune cells through the placenta and the transplacental passage of cells is in fact the norm. The fetal cells can persist in a wide range of woman's tissue following a pregnancy or an abortion and she becomes a chimera. Fetal cells have been found in the maternal circulation and they were shown to persist for almost three decades in humans, thus demonstrating long-term engraftment and survival capabilities. Microchimerism is a subject of much interest for a number of reasons. Studies of fetal microchimerism during pregnancy may offer explanations for complications of pregnancy, such as preeclampsia, as well as insights into the pathogenesis of autoimmune disease which usually ameliorates during pregnancy. The impact that the persistence of allogenic cells of fetal origin and the maternal immunological response to them has on the mother's health and whether it is detrimental or beneficial to the mother is still not clear. Although microchimerism has been implicated in some autoimmune diseases, fetal microchimerism is common in healthy individuals. On the beneficial side, it has been proposed that genetically disparate fetal microchimerism provides protection against some cancers, that fetal microchimerism can afford the mother new alleles of protection to some diseases she has not, that fetal microchimerism can enlarge the immunological repertoire of the mother improving her defense against aggressor. Fetal cells are often present at sites of maternal injury and may have an active role in the repair of maternal tissues.

Effect of parity on fetal and maternal microchimerism: interaction of grafts within a host?

Small amounts of genetically foreign cells (microchimerism, Mc) traffic between a mother and fetus during pregnancy. Commonly, these grafts durably persist. For women, multiple naturally acquired Mc grafts can accrue, as they harbor Mc from their own mothers (maternal Mc, MMc) and subsequently acquire fetal Mc (FMc) through pregnancy. The nature of interactions between these naturally acquired grafts may inform, and be informed by, observations in transplantation, including the effect of noninherited maternal HLA antigens (NIMA) and double-unit cord blood transplantation (CBT). We asked whether FMc and MMc are impacted by the addition of new grafts as evaluated by increasing parity. Mc was identified by quantitative PCR for a nonshared polymorphism unique to the Mc source. Despite increasing sources of Mc, FMc did not increase with increasing parity. MMc concentration was significantly lower with increasing parity. The odds ratio for detection of MMc for 2 or more births compared with 1 birth was .11 (95% CI 0.03-0.42, P = .001). These observations suggest that interactions occur among naturally acquired grafts and are of interest in light of recent observations of graft-graft interaction resulting in predominance of 1 unit in double-unit CBT and the correlation of MMc with the NIMA effect.