Microchimerism in the rheumatoid nodules of patients with rheumatoid arthritis

Deciphering the Role of Maternal Microchimerism in Offspring Autoimmunity: A Narrative Review

Feto-maternal microchimerism is the bidirectional transfer of cells through the placenta during pregnancy that can affect the health of both the mother and the offspring, even in childhood or adulthood. However, microchimerism seems to have different consequences in the mother, who already has a developed immune system, than in the fetus, which is vulnerable with immature defense mechanisms. Studies have shown that the presence of fetal microchimeric cells in the mother can be associated with reduced fetal growth, pre-eclampsia, miscarriage, premature birth, and the risk of autoimmune disease development in the future. However, some studies report that they may also play a positive role in the healing of maternal tissue, in cancer and cardiovascular disease. There are few studies in the literature regarding the role of maternal microchimeric cells in fetal autoimmunity. Even fewer have examined their association with the potential triggering of autoimmune diseases later in the offspring's life. The objectives of this review were to elucidate the mechanisms underlying the potential association between maternal cells and autoimmune conditions in offspring. Based on our findings, several hypotheses have been proposed regarding possible mechanisms by which maternal cells may trigger autoimmunity. In Type 1 diabetes, maternal cells have been implicated in either attacking the offspring's pancreatic β-cells, producing insulin, differentiating into endocrine and exocrine cells, or serving as markers of tissue damage. Additionally, several potential mechanisms have been suggested for the onset of neonatal lupus erythematosus. In this context, maternal cells may induce a graft-versus-host or host-versus-graft reaction in the offspring, function as effectors within tissues, or contribute to tissue healing. These cells have also been found to participate in inflammation and fibrosis processes, as well as differentiate into myocardial cells, potentially triggering an immune response. Moreover, the involvement of maternal microchimeric cells has been supported in conditions such as juvenile idiopathic inflammatory myopathies, Sjögren's syndrome, systemic sclerosis, biliary atresia, and rheumatoid arthritis. Conversely, no association has been found between maternal cells and celiac disease in offspring. These findings suggest that the role of maternal cells in autoimmunity remains a controversial topic that warrants further investigation.

Fetal-origin cells in maternal circulation correlate with placental dysfunction, fetal sex, and severe hypertension during pregnancy

Fetal microchimerism (FMc) arises when fetal cells enter maternal circulation, potentially persisting for decades. Increased FMc is associated with fetal growth restriction, preeclampsia, and anti-angiogenic shift in placenta-associated proteins in diabetic and normotensive term pregnancies. The two-stage model of preeclampsia postulates that placental dysfunction causes such shift in placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFLt-1), triggering maternal vascular inflammation and endothelial dysfunction. We investigated whether anti-angiogenic shift, fetal sex, fetal growth restriction, and severe maternal hypertension correlate with FMc in hypertensive disorders of pregnancy with new-onset features (n = 125). Maternal blood was drawn pre-delivery at > 25 weeks' gestation. FMc was detected by quantitative polymerase chain reaction targeting paternally inherited unique fetal alleles. PlGF and sFlt-1 were measured by immunoassay. We estimated odds ratios (ORs) by logistic regression and detection rate ratios (DRRs) by negative binomial regression. PlGF correlated negatively with FMc quantity (DRR = 0.2, p = 0.005) and female fetal sex correlated positively with FMc prevalence (OR = 5.0, p < 0.001) and quantity (DRR = 4.5, p < 0.001). Fetal growth restriction no longer correlated with increased FMc quantity after adjustment for correlates of placental dysfunction (DRR = 1.5, p = 0.272), whereas severe hypertension remained correlated with both FMc measures (OR = 5.5, p = 0.006; DRR = 6.3, p = 0.001). Our findings suggest that increased FMc is independently associated with both stages of the two-stage preeclampsia model. The association with female fetal sex has implications for microchimerism detection methodology. Future studies should target both male and female-origin FMc and focus on clarifying which placental mechanisms impact fetal cell transfer and how FMc impacts the maternal vasculature.

Fetal microchimerism and the two-stage model of preeclampsia

Fetal cells cross the placenta during pregnancy and some have the ability to persist in maternal organs and circulation long-term, a phenomenon termed fetal microchimerism. These cells often belong to stem cell or immune cell lineages. The long-term effects of fetal microchimerism are likely mixed, potentially depending on the amount of fetal cells transferred, fetal-maternal histocompatibility and fetal cell-specific properties. Both human and animal data indicate that fetal-origin cells partake in tissue repair and may benefit maternal health overall. On the other hand, these cells have been implicated in inflammatory diseases by studies showing increased fetal microchimerism in women with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. During pregnancy, preeclampsia is associated with increased cell-transfer between the mother and fetus, and an increase in immune cell subsets. In the current review, we discuss potential mechanisms of transplacental transfer, including passive leakage across the compromised diffusion barrier and active recruitment of cells residing in the placenta or fetal circulation. Within the conceptual framework of the two-stage model of preeclampsia, where syncytiotrophoblast stress is a common pathophysiological pathway to maternal and fetal clinical features of preeclampsia, we argue that microchimerism may represent a mechanistic link between stage 1 placental dysfunction and stage 2 maternal cardiovascular inflammation and endothelial dysfunction. Finally, we postulate that fetal microchimerism may contribute to the known association between placental syndromes and increased long-term maternal cardiovascular disease risk. Fetal microchimerism research represents an exciting opportunity for developing new disease biomarkers and targeted prophylaxis against maternal diseases.

The development of an indel panel for microchimerism detection

OBJECTIVES

The aim of the study was to create a simple assay for microchimerism detection independent of sex and without HLA genotyping.

METHODS

The method is based on detection of insertion or deletions utilizing a multiplex PCR followed by fragment analysis by capillary electrophoresis, and probe-based qPCR assays. A total of 192 samples, taken either before pregnancy, during 1st trimester, or either during 2nd trimester or at miscarriage, obtained from a cohort of 97 female patients with either primary or secondary recurrent pregnancy loss, were screened for fetal microchimerism by the indel panel as well as an existing assay based on detection of the Y-chromosome marker; DYS14.

RESULTS

The overall prevalence of DYS14 positive samples was 29% (55/192) whereas 32% (61/192) tested positive by the indel method. There was an overall agreement of 64% (122/192) between the results obtained by the two methods. A Fisher's Exact test showed no statistic significant difference in the prevalence of microchimerism detected by the two methods at any of the three times of sampling. The distribution of the number of positive wells detected by both methods were compared by a Mann-Whitney U test, which showed no statistically significant difference at any of the three times of sampling.

CONCLUSION

The data indicates that microchimerism can be detected efficiently by the indel method. This makes it possible to detect both female and male cells without the need of HLA-genotyping. Furthermore, the indel method has potential to be implemented as a routine analysis. This will remove the sex bias in future explorations of the role microchimerism plays in health and disease.

Male microchimerism in peripheral blood from women with multiple sclerosis in Isfahan Province

Multiple sclerosis (MS) is referred to as an organ-specific T-cell-mediated autoimmune disease of the central nervous system (CNS). Different genetic and environmental factors increase the risk of developing MS. In recent years, microchimerism (Mc) has been widely studied in autoimmune diseases, although the exact role of this phenomenon in human health is not known well. Microchimerism is the low level presence of DNA or cells from one individual into the tissue or circulation of another individual. In the current study, we evaluated the association of fetal microchimerism (FMc) with MS in Isfahan province. In this study, we enrolled 68 women in four groups. Two groups were MS patients with or without a pregnancy for a son, and the other two groups were MS-negative patients with or without a pregnancy for a son. The presence of the male genome assessed and compared in these groups. Four millilitres of peripheral blood were collected from all subjects in the tube containing EDTA and DNA was extracted. Real-time PCR assay was used for the DAZ (deleted in azoospermia) region Yq 11.23 as a marker for male microchimerism in all subjects. Our results showed that the percentage of DAZ (male genome)-positive women was significantly higher in MS-positive women given birth to a son in comparison with the other three groups. Our results also revealed no significant correlation between the percentage of DAZ-positive women and Expanded Disability Status Scale (EDSS) score and age of onset in the patients' group. For future studies, we suggest enrolling subjects who MS diagnosis occurred before and after pregnancy with a son. Comparing FMc in these two groups might provide a better understanding of the possible role of FMc in later development of MS.

Genomic evidence of Y chromosome microchimerism in the endometrium during endometriosis and in cases of infertility

BACKGROUND

Previous studies, which were primarily based on the fluorescent in-situ hybridisation (FISH) technique, revealed conflicting evidence regarding male foetal microchimerism in endometriosis. FISH is a relatively less sensitive technique, as it is performed on a small portion of the sample. Additionally, the probes used in the previous studies specifically detected centromeric and telomeric regions of Y chromosome, which are gene-sparse heterochromatised regions. In the present study, a panel of molecular biology tools such as qPCR, expression microarray, RNA-seq and qRT-PCR were employed to examine the Y chromosome microchimerism in the endometrium using secretory phase samples from fertile and infertile patients with severe (stage IV) ovarian endometriosis (OE) and without endometriosis.

METHODS

Microarray expression analysis followed by validation using RNA-seq and qRT-PCR experiments at the RNA levels and further validation at the DNA level by qPCR of target inserts for selected targets in eutopic endometrium samples obtained from control (CON) and stage IV ovarian endometriosis (OE), either from fertile (FCON and FOE; n = 30/each) or infertile (ICON and IOE; n = 30/each) women, were performed.

RESULTS

Six coding (AMELY, PCDH11, SRY, TGIF2LY, TSPY3, and USP9Y) and 10 non-coding (TTTY2, TTTY4C, TTTY5, TTTYY6, TTTY8, TTTY10, TTTY14, TTTY21, TTTY22, and TTTY23) genes exhibited a bimodal pattern of expression characterised by low expression in samples from fertile patients and high expression in samples from infertile patients. Seven coding MSY-linked genes (BAGE, CD24, EIF1AY, NLGN4Y, PRKY, VCY and ZFY) exhibited differential regulation in microarray analysis, and this change was validated by RNA-seq or qRT-PCR. DNA inserts for 7 genes in various samples were validated by qPCR. The prevalence and concentration of PCR-positive target inserts for BAGE, PRKY, TTTY9A and ZFY displayed higher values in the fertile, control (FCON) patients compared with the fertile, endometriosis patients (FOE).

CONCLUSION

Several coding and non-coding MSY-linked genes displayed microchimerism as evidenced by the presence of their respective DNA inserts, along with their differential transcript expression, in the endometrium during endometriosis and in cases of infertility.

A case of maternal-foetal chimerism identified during routine histocompatibility testing for hematopoietic stem cell transplantation

This report describes a case of maternal-foetal chimerism identified in a boy diagnosed with SCID, who underwent HLA testing in preparation for HSCT. The first analysis was carried out on DNA from peripheral blood and included HLA-A, HLA-B, HLA-DRB1 typing using PCR-SSO. The patient's HLA-B typing results were noninterpretable. All samples were re-typed for HLA-B using PCR-SSP, again resulting in noninterpretable typing of patient's HLA-B. In both cases, several weak positive probes/reactions interfered with the interpretation when using commercial software. Next round of HLA typing, using PCR-SSP and PCR-SSO methods, included the patient's bone marrow sample and HLA-C locus, but interpretation was again not possible. The PCR-STR analysis performed on both peripheral blood and bone marrow samples revealed seven STRs for which two maternal and one paternal allele were detected. Retrospective manual interpretation of HLA-B and HLA-C typing revealed that weak positive reactions were indeed owed to paternal HLA-B and HLA-C alleles and that the patient had both maternal and one paternal allele. Retyping of HLA-B and HLA-C loci and STR analysis on the patient's buccal cells sample revealed the expected one maternal/one paternal allele pattern. In summary, the combination of several different typing methods and manual interpretation were necessary to obtain the patient's HLA typing results.

Lack of Evidence That Male Fetal Microchimerism is Present in Endometriosis

INTRODUCTION

Fetal microchimerism has been implicated in the etiology of autoimmune diseases. This study was done to test the hypothesis that male fetal microchimerism is present in eutopic and ectopic endometrium (EM) obtained from women with endometriosis but not in eutopic EM from women without endometriosis.

METHODS

A total of 31 patients were selected, including women with endometriosis (paired eutopic and ectopic EM; n = 19) and women without endometriosis (eutopic EM; n = 12). Tricolor interphase fluorescence in situ hybridization analysis was performed by cohybridization of CEP Y SpectrumAqua and CEP X SpectrumGreen (SG)/CEP Y SpectrumOrange probes.

RESULTS

Ectopic EM from women with endometriosis had 75% XX chromosomes (double SG signals) and 25% X chromosomes (single SG signal). Y chromosomes were not observed in any of the eutopic/ectopic endometrial tissues from cases or controls.

CONCLUSIONS

We were unable to confirm our hypothesis that male fetal microchimerism is present in eutopic and/or ectopic EM obtained from women with endometriosis.

Fetal microchimerism and maternal health: a review and evolutionary analysis of cooperation and conflict beyond the womb

The presence of fetal cells has been associated with both positive and negative effects on maternal health. These paradoxical effects may be due to the fact that maternal and offspring fitness interests are aligned in certain domains and conflicting in others, which may have led to the evolution of fetal microchimeric phenotypes that can manipulate maternal tissues. We use cooperation and conflict theory to generate testable predictions about domains in which fetal microchimerism may enhance maternal health and those in which it may be detrimental. This framework suggests that fetal cells may function both to contribute to maternal somatic maintenance (e.g. wound healing) and to manipulate maternal physiology to enhance resource transmission to offspring (e.g. enhancing milk production). In this review, we use an evolutionary framework to make testable predictions about the role of fetal microchimerism in lactation, thyroid function, autoimmune disease, cancer and maternal emotional, and psychological health.

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Microchimerism in recurrent miscarriage

Maternal-fetal cell exchange during pregnancy results in acquisition of microchimerism, which can durably persist in both recipients. Naturally acquired microchimerism may impact maternal-fetal interaction in pregnancy. We conducted studies to ask whether microchimerism that a woman acquired from her own mother is detectable before or during pregnancy in women with recurrent miscarriage. Fetal microchimerism was also assayed. Women with primary idiopathic recurrent miscarriage (n=23) and controls (n=31) were studied. Genotyping was conducted for probands, their mothers and the fetus, a non-shared polymorphism identified and quantitative polymerase chain reaction performed to measure microchimerismin peripheral blood mononuclear cells. Preconception comparisons were made between recurrent miscarriage subjects and controls, using logistic regression and Wilcoxon rank sum. Longitudinal microchimerism in subsequent pregnancies of recurrent miscarriage subjects was described. There was a trend toward lower preconception detection of microchimerism in recurrent miscarriage versus controls, 6% vs. 19% (1/16 vs. 6/31, P=0.2). During pregnancy, 3/11 (27%) of recurrent miscarriage subjects who went on to have a birth had detection of microchimerism from their own mother, whereas neither of two subjects who went on to miscarry had detection (0/2). This initial data suggest that microchimerism from a woman's own mother, while detectable in women with recurrent miscarriage, may differ from controls and according to subsequent pregnancy outcome. Further studies are needed to determine the cell types, quantities and any potential functional role of microchimerism in recurrent miscarriage.

Toxoplasmosis--a global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries

BACKGROUND

Toxoplasmosis is becoming a global health hazard as it infects 30-50% of the world human population. Clinically, the life-long presence of the parasite in tissues of a majority of infected individuals is usually considered asymptomatic. However, a number of studies show that this 'asymptomatic infection' may also lead to development of other human pathologies.

AIMS OF THE STUDY

The purpose of the study was to collect available geoepidemiological data on seroprevalence of toxoplasmosis and search for its relationship with mortality and disability rates in different countries.

METHODS AND FINDINGS

Prevalence data published between 1995-2008 for women in child-bearing age were collected for 88 countries (29 European). The association between prevalence of toxoplasmosis and specific disease burden estimated with age-standardized Disability Adjusted Life Year (DALY) or with mortality, was calculated using General Linear Method with Gross Domestic Product per capita (GDP), geolatitude and humidity as covariates, and also using nonparametric partial Kendall correlation test with GDP as a covariate. The prevalence of toxoplasmosis correlated with specific disease burden in particular countries explaining 23% of variability in disease burden in Europe. The analyses revealed that for example, DALY of 23 of 128 analyzed diseases and disease categories on the WHO list showed correlations (18 positive, 5 negative) with prevalence of toxoplasmosis and another 12 diseases showed positive trends (p<0.1). For several obtained significant correlations between the seroprevalence of toxoplasmosis and specific diseases/clinical entities, possible pathophysiological, biochemical and molecular explanations are presented.

CONCLUSIONS

The seroprevalence of toxoplasmosis correlated with various disease burden. Statistical associations does not necessarily mean causality. The precautionary principle suggests however that possible role of toxoplasmosis as a triggering factor responsible for development of several clinical entities deserves much more attention and financial support both in everyday medical practice and future clinical research.

Analysis of maternal microchimerism in rhesus monkeys (Macaca mulatta) using real-time quantitative PCR amplification of MHC polymorphisms

Although pregnancy-associated microchimerism is known to exist in humans, its clinical significance remains unclear. Fetal microchimerism has been documented in rhesus monkeys, but the trafficking and persistence of maternal cells in the monkey fetus and infant have not been fully explored. To investigate the frequency of maternal microchimerism in the rhesus monkey (Macaca mulatta), a real-time polymerase chain reaction (PCR) strategy was developed and validated to target polymorphic major histocompatibility complex (MHC) gene sequences. Informative PCR assays were identified for 19 of 25 dams and their respective offspring. Analyses were performed on tissues (thymus, liver, spleen, lymph nodes, and bone marrow) and peripheral blood mononuclear cells (PBMCs) collected prenatally and postnatally in a subset of animals. Seven of 19 monkeys had detectable maternal microchimerism in at least one compartment (range: 0.001-1.9% chimeric cells). In tissues, maternal microchimerism was found in 2 of 7 fetuses and 3 of 12 juveniles (1-1.5 years of age), and most of the animals that were positive had microchimeric cells in more than one tissue. Maternal microchimerism was detected in PBMCs from all (4 of 4) fetuses. These observations suggest that maternal microchimerism occurs in the rhesus monkey fetus and can be detected in tissues in a subset of offspring after birth.

Maternal microchimerism protects against the development of asthma

BACKGROUND

Maternal asthma and child's sex are among the most significant and reproducible risk factors for the development of asthma. Although the mechanisms for these effects are unknown, they likely involve nonclassical genetic mechanisms. One such mechanism could involve the transfer and persistence of maternal cells to her offspring, a common occurrence known as maternal microchimerism (MMc). MMc has been associated with many autoimmune diseases but has not been investigated for a role in asthma or allergic disease.

OBJECTIVE

We hypothesized that some of the observed risks for asthma may be due to different rates of transmission or persistence of maternal cells to children of mothers with asthma compared with children of mothers without asthma, or to sons compared with daughters. We further hypothesized that rates of MMc differ between children with and without asthma.

METHODS

We tested these hypotheses in 317 subjects from 3 independent cohorts by using a real-time quantitative PCR assay to detect a noninherited HLA allele in the child.

RESULTS

MMc was detected in 20.5% of the subjects (range 16.8%-27.1% in the 3 cohorts). We observed lower rates of asthma among MMc-positive subjects than among MMc-negative subjects (odds ratio, 0.38; 95% CI, 0.19-0.79; P = .029). Neither maternal asthma nor sex of the child was a significant predictor of MMc in the child (P = .81 and .15, respectively).

CONCLUSIONS

Our results suggest for the first time that MMc may protect against the development of asthma.

Male microchimerism in the human female brain

In humans, naturally acquired microchimerism has been observed in many tissues and organs. Fetal microchimerism, however, has not been investigated in the human brain. Microchimerism of fetal as well as maternal origin has recently been reported in the mouse brain. In this study, we quantified male DNA in the human female brain as a marker for microchimerism of fetal origin (i.e. acquisition of male DNA by a woman while bearing a male fetus). Targeting the Y-chromosome-specific DYS14 gene, we performed real-time quantitative PCR in autopsied brain from women without clinical or pathologic evidence of neurologic disease (n=26), or women who had Alzheimer's disease (n=33). We report that 63% of the females (37 of 59) tested harbored male microchimerism in the brain. Male microchimerism was present in multiple brain regions. Results also suggested lower prevalence (p=0.03) and concentration (p=0.06) of male microchimerism in the brains of women with Alzheimer's disease than the brains of women without neurologic disease. In conclusion, male microchimerism is frequent and widely distributed in the human female brain.