Whole embryonic detection of maternal microchimeric cells highlights significant differences in their numbers among individuals.

During pregnancy in placental mammals, small numbers of maternal cells (maternal microchimeric cells, or MMc cells) migrate into the fetus and persist decades, or perhaps for the rest of their lives, and higher frequencies of MMc cells are reported to correlate with variety of phenomena, such as immune tolerance, tissue repair, and autoimmune diseases. While detection of these MMc cells is considered in all pregnancies, their frequency differs largely according to tissue type and disease cases, and it remains unclear whether the number of MMc cells differs significantly among embryos in normal pregnancies. Here, for the first time, we developed a whole embryonic detection method for MMc cells using transgenic mice and counted live MMc cells in each individual embryo. Using this technique, we found that the number of MMc cells was comparable in most of the analyzed embryos; however, around 500 times higher number of MMc cells was detected in one embryo at the latest stage. This result suggests that the number of MMc cells could largely differ in rare cases with unknown underlying mechanisms. Our methodology provides a basis for testing differences in the numbers of MMc cells among individual embryos and for analyzing differences in MMc cell type repertoires in future studies. These data could provide a hint toward understanding the mechanisms underlying the variety of apparently inconsistent MMc-related phenomena.

Peripheral Plasmodium falciparum Infection in Early Pregnancy Is Associated With Increased Maternal Microchimerism in the Offspring.

BACKGROUND: Placental malaria has been associated with increased cord blood maternal microchimerism (MMc), which in turn may affect susceptibility to malaria in the offspring. We sought to determine the impact of maternal peripheral Plasmodium falciparum parasitemia during pregnancy on MMc and to determine whether maternal cells expand during primary parasitemia in the offspring. METHODS: We conducted a nested cohort study of maternal-infant pairs from a prior pregnancy malaria chemoprevention study. Maternal microchimerism was measured by quantitative polymerase chain reaction targeting a maternal-specific marker in genomic DNA from cord blood, first P falciparum parasitemia, and preparasitemia. Logistic and negative binomial regression were used to assess the impact of maternal peripheral parasitemia, symptomatic malaria, and placental malaria on cord blood MMc. Generalized estimating equations were used to assess predictors of MMc during infancy. RESULTS: Early maternal parasitemia was associated with increased detection of cord blood MMc (adjusted odds ratio = 3.91, P = .03), whereas late parasitemia, symptomatic malaria, and placental malaria were not. The first parasitemia episode in the infant was not associated with increased MMc relative to preparasitemia. CONCLUSIONS: Maternal parasitemia early in pregnancy may increase the amount of MMc acquired by the fetus. Future work should investigate the impact of this MMc on immune responses in the offspring.

Cytogenetic profile of patients with clinical spectrum of ambiguous genitalia, amenorrhea, and Turner phenotype: A 21-year single-center experience.

The aim of the present study was to determine the frequency and nature of chromosomal abnormalities involved in patients with the clinical spectrum of ambiguous genitalia (AG), amenorrhea, and Turner phenotype, in order to compare them with those reported elsewhere. The study was conducted in the Cytogenetic Department of Pasteur Institute of Morocco, and it reports on the patients who were recruited between 1996 and 2016. Cytogenetic analysis was performed according to the standard method. Among 1,415 patients, chromosomal abnormalities were identified in 7.13% (48/673) of patients with AG, 17.39% (28/161) of patients with primary amenorrhea (PA), 4% (1/25) of patients with secondary amenorrhea, and 23.20% (129/556) of patients with Turner phenotype. However, Turner syndrome was diagnosed in 0.89% (6/673) of patients with AG, 10.56% (17/161) of patients with PA, and 19.78% (110/556) of patients with Turner phenotype. In addition, Klinefelter syndrome and mixed gonadal dysgenesis were confirmed in 2.97% and 1.93% of patients, respectively, with AG, while, chimerism, trisomy 8, and trisomy 13 were confirmed only in 0.15% each. Trisomy 21 was confirmed in patients with AG and Turner phenotype (0.15% and 0.36%, respectively). Moreover, 5.60% (9/161) of patients with PA have been diagnosed as having sex reversal. Thus, the frequency of chromosomal abnormalities observed in Moroccan patients with PA is comparable to that reported in Tunisia, Turkey, Iran, and Hong Kong. However, the frequency is significantly less than that identified in India, Malaysia, Italy, and Romania.

Microchimerism in Ghanaian children recipients of whole blood transfusion for severe anaemia.

BACKGROUND AND OBJECTIVES: Transfusion-acquired microchimerism (TA-Mc) has been reported in major trauma but not in young children despite relative immunodeficiency who, in sub-Saharan Africa, often suffer severe anaemia related to haemoglobinopathies or primary malaria infections. We examined the hypothesis that such massive red cell destructions might provide conditions favourable to TA-Mc, particularly when exposed to massive amounts of parasite antigens. MATERIALS AND METHODS: Twenty-seven female children <5 years transfused with male whole blood for severe anaemia (13 with acute malaria and 14 with other causes) were retrospectively identified, and a blood sample was collected >6 months post-transfusion. Four whole blood samples from paediatric females transfused with blood from female donors and five secondary school female students never pregnant, never transfused were used as negative controls. RESULTS: Nineteen patients (70%) carried male Mc with four (15%) having high levels of Mc (>100 genome equivalent of male cells/million of host cells) compared to three controls (37·5%). There was no difference in frequency or quantity of male Mc between paediatric patients with severe malaria and paediatric patients with other causes of severe anaemia. TA-Mc was not correlated with patient age, duration of whole blood storage or lymphocyte load transfused. After a median of 7 months post-transfusion, acute malaria did not increase the frequency of TA-Mc. One negative control appeared to carry low-level male cells. CONCLUSION: Transfusion-acquired microchimerism appears frequent in young children transfused with whole blood for severe anaemia.

Evaluation of Chimerism Dynamics after Allogeneic Hematopoietic Stem Cell Transplantation in Children with Nonmalignant Diseases.

It is recognized that chimerism following hematopoietic stem cell transplantation (HSCT) is a dynamic process. The aims of this study were to describe the evolution of chimerism in children with nonmalignant diseases who underwent allogeneic HSCT, and to analyze the risk factors influencing chimerism status. A total of 101 HSCTs were performed in 85 patients with nonmalignant diseases. The donor was unrelated in 62.4% of HSCTs. Reduced-intensity conditioning (RIC) regimen was administered in 48.5% of patients. Acute graft-versus-host disease (aGVHD) occurred in 51.7% and chronic GVHD (cGVHD) in 39.7% of patients. Analysis of chimerism was performed through amplification of 9 specific short tandem repeats by polymerase chain reaction at engraftment and 1, 6, and 12 months after HSCT. Upon first evaluation, complete chimerism (CC) was detected in 34.7% and mixed chimerism (MC) in 55.4%, whereas graft failure occurred in 9.9% of patients. Severe aGVHD was associated with CC (P = .031). The last chimerism evaluation showed CC in 72.1%, stable MC in 12.8%, and progressive MC in 3.5%. CC was associated with a higher incidence of aGVHD (P = .016) and cGVHD (P = .022), whereas the RIC regimen was associated with graft failure (P = .026). One- and 3-year overall survival (OS) was 87.4% and 80.5%, respectively, with a lower OS at 3 years in patients with CC compared with those with MC (P = .008). aGVHD and cGVHD represent factors favoring CC, thus close, careful follow-up of chimerism is recommended in patients affected by nonmalignant disease.

Maternal Microchimerism Predicts Increased Infection but Decreased Disease due to Plasmodium falciparum During Early Childhood.

Background: A mother's infection with placental malaria (PM) can affect her child's susceptibility to malaria, although the mechanism remains unclear. The fetus acquires a small amount of maternal cells and DNA known as maternal microchimerism (MMc), and we hypothesized that PM increases MMc and that MMc alters risk of Plasmodium falciparum malaria during infancy. Methods: In a nested cohort from Muheza, Tanzania, we evaluated the presence and level of cord blood MMc in offspring of women with and without PM. A maternal-specific polymorphism was identified for each maternal-infant pair, and MMc was assayed by quantitative polymerase chain reaction. The ability of MMc to predict malaria outcomes during early childhood was evaluated in longitudinal models. Results: Inflammatory PM increased the detection rate of MMc among offspring of primigravidae and secundigravidae, and both noninflammatory and inflammatory PM increased the level of MMc. Detectable MMc predicted increased risk of positive blood smear but, interestingly, decreased risk of symptomatic malaria and malaria hospitalization. Conclusions: The acquisition of MMc may result in increased malaria infection but protection from malaria disease. Future studies should be directed at the cellular component of MMc, with attention to its ability to directly or indirectly coordinate anti-malarial immune responses in the offspring.

A Study of Human Leukocyte Antigen Mismatched Cellular Therapy (Stem Cell Microtransplantation) in High-Risk Myelodysplastic Syndrome or Transformed Acute Myelogenous Leukemia.

UNLABELLED: The treatment outcomes of myelodysplastic syndrome (MDS) and transformed acute myelogenous leukemia (tAML) remain very unsatisfactory. We designed a combination of human leukocyte antigen (HLA)-mismatched hematopoietic stem cell microtransplantation (MST) with chemotherapy for patients with MDS and tAML and evaluated its effects and toxicity. Patients were between 13 and 79 years old. Patients with MDS (n=21) were given HLA-mismatched MST combined with decitabine and cytarabine; patients with tAML (n=22) were given HLA-mismatched MST combined with decitabine and cytarabine, and also mitoxantrone. Patients in complete remission (CR) also received MST plus decitabine and medium-dose cytarabine chemotherapy without graft-versus-host disease (GVHD) prophylaxis. The overall response rate of the patients with MDS was significantly higher than that of those with tAML (81% vs. 50%; p=.03). The CR rates were 52.4% and 36.4% in the two groups, respectively. There was no difference in the cytogenetic CR rate between the MDS and tAML groups (85.7% vs. 70%, respectively; p=.7). The 24-month overall survival of the patients with MDS was significantly higher than that of the patients with tAML (84.7% and 34.1%, respectively; p=.003). The median recovery times of neutrophils and platelets were, respectively, 14 and 17 days in the patients with MDS, and 16 and 19 days in those with tAML. The treatment-related mortality rates were 4.8% and 18.2%, respectively, in the MDS and tAML groups (p=.34). No GVHD was observed in any patient. Microtransplantation combined with decitabine and chemotherapy may provide a novel, effective, and safe treatment for high-risk MDS and tAML. SIGNIFICANCE: Microtransplantation (MST) refers to regular chemotherapy combined with granulocyte colony-stimulating factor-mobilized peripheral blood stem cell infusion of human leukocyte antigen-mismatched donor cells without using immunosuppressive agents. It aims to support hematopoietic recovery and perform graft-versus-leukemia (GVL) effects but differs from traditional allogeneic stem cell transplantation because the rate of donor cell chimerism is low and there is and no graft-versus-host disease (GVHD) risk. Thus, a trial was designed to evaluate the safety and efficacy of MST in patients with myelodysplastic syndrome and those with transformed acute myelogenous leukemia. Higher complete remission and cytogenetic complete response rates were observed, and the treatment improved disease progress-free survival, sped hematopoietic recovery, and avoided GVHD.

Fetal microchimerism in kidney biopsies of lupus nephritis patients may be associated with a beneficial effect.

INTRODUCTION: Microchimeric male fetal cells (MFCs) have been associated with systemic lupus erythematosus, and published studies have further correlated MFC with lupus nephritis (LN). In the present study, we evaluated the frequency of MFC in the renal tissue of patients with LN. METHODS: Twenty-seven renal biopsies were evaluated: Fourteen were from women with clinical and laboratory findings of LN, and thirteen were from controls. Genomic DNA was extracted from kidney biopsies, and the male fetal DNA was quantified using real-time quantitative polymerase chain reactions for the detection of specific Y chromosome sequences. RESULTS: MFCs were detected in 9 (64%) of 14 of patients with LN, whereas no MFCs were found in the control group (P = 0.0006). No differences in pregnancy history were found between patients with LN and the control group. Significantly higher amounts of MFCs were found in patients with LN with serum creatinine ≤1.5 mg/dl. Furthermore, women with MFCs had significantly better renal function at the time of biopsy (P = 0.03). In contrast, patients with LN without MFCs presented with more severe forms of glomerulonephritis (World Health Organization class IV = 60% and class V = 40%). CONCLUSIONS: Our data indicate a high prevalence of MFCs in renal biopsy specimens from women with LN, suggesting a role for MFCs in the etiology of LN. The present report also provides some evidence that MFCs could have a beneficial effect in this disease.

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.

The occurrence of fetal microchimeric cells in endometrial tissues is a very common phenomenon in benign uterine disorders, and the lower prevalence of fetal microchimerism is associated with better uterine cancer prognoses.

This is the first study carried out to describe the role of fetal microchimerism (FM) in the pathogenesis of uterine cancer. The prevalence and concentration of male fetal microchimeric cells (FMCs) were examined in endometrial tissues in relation to subtypes of uterine cancer, and the histological grade and stage of the tumor. FM occurrence was analyzed in relation to risk factors, including hypertension, obesity, type 2 diabetes, dyslipidemia, age at cancer diagnosis, and patient pregnancy history. The prevalence and concentration of FMCs were examined in endometrial tissues using real-time polymerase chain reaction, SRY and ß-globin sequences as markers for male fetal FMCs and total DNA. The studied group involved 47 type 1 endometrial cancers, 28 type 2 endometrial cancers, and 41 benign uterine diseases. While the prevalence of FM was decreased only in type 1 endometrial cancer, compared with benign uterine disorders (38.3% vs.70.7%; odds ratio [OR]=0.257, 95% confidence interval [CI]: 0.105 to 0.628, p=0.003), FMC concentrations did not differ within examined groups. The lower FM prevalence was detected in low-grade (grade 1 and grade 2) endometrioid cancer (38.3% vs. 70.7%, OR=0.256, 95% CI: 0.105 to 0.627, p=0.003) and in FIGO 1 tumors (40.7% vs. 70.7%, OR=0.285, 95% CI: 0.120 to 0.675, p=0.004). No correlation between FM prevalence or FMC concentrations and risk factors was demonstrated. A lower prevalence of male FM seemed to be associated with better prognoses in uterine cancer based on tumor subtype, histological grade, and stage of the tumor.

Male microchimerism at high levels in peripheral blood mononuclear cells from women with end stage renal disease before kidney transplantation.

Patients with end stage renal diseases (ESRD) are generally tested for donor chimerism after kidney transplantation for tolerance mechanism purposes. But, to our knowledge, no data are available on natural and/or iatrogenic microchimerism (Mc), deriving from pregnancy and/or blood transfusion, acquired prior to transplantation. In this context, we tested the prevalence of male Mc using a real time PCR assay for DYS14, a Y-chromosome specific sequence, in peripheral blood mononuclear cells (PBMC) from 55 women with ESRD, prior to their first kidney transplantation, and compared them with results from 82 healthy women. Male Mc was also quantified in 5 native kidney biopsies obtained two to four years prior to blood testing and in PBMC from 8 women collected after female kidney transplantation, several years after the initial blood testing. Women with ESRD showed statistically higher frequencies (62%) and quantities (98 genome equivalent cells per million of host cells, gEq/M) of male Mc in their PBMC than healthy women (16% and 0.3 gEq/M, p<0.00001 and p = 0.0005 respectively). Male Mc was increased in women with ESRD whether they had or not a history of male pregnancy and/or of blood transfusion. Three out of five renal biopsies obtained a few years prior to the blood test also contained Mc, but no correlation could be established between earlier Mc in a kidney and later presence in PBMC. Finally, several years after female kidney transplantation, male Mc was totally cleared from PBMC in all women tested but one. This intriguing and striking initial result of natural and iatrogenic male Mc persistence in peripheral blood from women with ESRD raises several hypotheses for the possible role of these cells in renal diseases. Further studies are needed to elucidate mechanisms of recruitment and persistence of Mc in women with ESRD.

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.

Aggregation of thyroid autoantibodies in twins from opposite-sex pairs suggests that microchimerism may play a role in the early stages of thyroid autoimmunity.

CONTEXT: Microchimerism is the presence of small populations of cells from one individual in another genetically distinct individual. This phenomenon can arise from pregnancy, blood transfusion, or bidirectional cell trafficking between twins in utero. Microchimerism has recently been proposed to play a role in the pathogenesis of thyroid autoimmunity. In that case, twins from opposite-sex pairs (OS) should have an increased risk of thyroid autoantibodies (TA). AIM: The aim of the study was to compare the frequency of TA in twin individuals from OS and monozygotic (MZ) twin pairs. DESIGN: This was a case-control study of 240 individuals (120 females and 120 males) from OS twin pairs (cases) and 568 control individuals from MZ pairs (284 females and 284 males). METHODS: Antibodies toward thyroid peroxidase (TPOAb), thyroglobulin (TgAb), and the TSH receptor (TSHRAb) were measured and considered positive if greater than 60 U/ml, greater than 60 U/ml, and greater than 1.0 U/liter, respectively. RESULTS: The frequency of TPOAb, TgAb, and TSHRAb among female cases was 15.0, 5.0, and 4.2%, respectively, which was higher than the corresponding prevalences in the female control population: 7.4% (P = 0.018), 1.1% (P = 0.023), and 0.7% (P = 0.026), respectively. However, when corrected for the number of phenotypes studied (TPOAb, TgAb, TSHRAb, and any thyroid antibody), the association remained significant only in the combined group, P(corrected) = 0.012. Essentially similar results were obtained in males. CONCLUSION: Both female and male twins from OS pairs, as opposed to MZ pairs, have an increased frequency of TA, indicating a potential role of microchimerism in developing TA.

Female predominance and X chromosome defects in autoimmune diseases.

It is known that autoimmune diseases cumulatively affect 5-10% of the general population. Although knowledge of pathogenesis has become more refined, laboratory diagnosis more accurate, and therapy more effective, the reasons for the female preponderance of these conditions remain unclear. The most intriguing theory to explain the female preponderance is currently related to sex chromosomes, as women with autoimmune diseases manifest a higher rate of circulating cells with a single X chromosome (i.e. X monosomy). In addition, there have been several reports on the role of X chromosome gene dosage through inactivation or duplication in autoimmunity. Taken together, sex chromosome changes might constitute the common trait of the susceptibility to autoimmune diseases.

High prevalence of microchimerism in female patients.

Evaluation of free plasma DNA has been suggested as one of the option to detect organ rejection in transplanted patients. However, the presence of chimeric cells in organs could make this approach complicated. To study the presence of Y-chromosome chimeric cells, we examined biopsy samples of 40 thoracic aortas of female donors and recipients. Using nested polymerase chain reaction, the presence of Y-chromosome-specific DNA sequences was detected in 19 (47.5%) analyzed tissue samples. Thus, free DNA originating from more than two genomes could be present in plasma in such a high proportion of cases. This phenomenon makes the use of plasma free DNA for the detection of organ rejection difficult and impractical.

[Chimerism: origin and medical implications]. / Quimerismo: origen e implicaciones médicas.

The organism whose cells come from different individuals is called chimera. It is frequently observed in nature: pregnancy, organ transplantation or transfusion are considered chimeric cell sources. It has been involved in autoimmune diseases development such as scleroderma, because of similarities between it and graft versus host disease, long term persistence of fetal cells in women and the finding of greater number of chimeric cells in affected women than healthy ones. It is not strictly a disease but might be considered helpful in non-invasive prenatal diagnosis and damaged organs regeneration.

Association of maternal histocompatibility at class II HLA loci with maternal microchimerism in the fetus.

For investigating the possible influence of maternal-fetal HLA compatibility on maternal microchimerism, DNA samples from blood of 120 maternal-fetal pairs were genotyped at two polymorphic loci: glutathione-S-transferase M1 (GSTM1) and angiotensin-converting enzyme (ACE). Informative pairs (mother heterozygous/fetus homozygous at one of the two loci) were then tested by quantitative real-time PCR for the noninherited maternal allele(s) and genotyped at the HLA-A, B, and C class I loci and/or at the DRB1 and/or DQB1 class II loci. Small numbers of maternal cells were detected in the circulation of 16 of the 30 informative second- and third-trimester fetuses. Comparison with HLA data suggested an association between microchimerism and maternal compatibility at the class II DRB1 and/or DQB1 HLA loci and with the maternal HLA-DQB1*0301 allele. There was no relationship between maternal microchimerism and maternal-fetal HLA compatibility at other HLA loci or with gestational age, fetal anomalies, or red cell or platelet isoimmunity.