Foeto-maternal compatibility in HLA-DR, -DQ, and -DP loci in Finnish couples suffering from recurrent spontaneous abortions

HLA allele associations in idiopathic recurrent spontaneous abortion patients from India

BACKGROUND:

Rejection of semiallogenic foetus in recurrent spontaneous abortion (RSA) has been postulated to be a consequence of genetic and immunological phenomena.

AIM:

To evaluate the role of human leukocyte antigen (HLA) alleles in RSA in Indian couples.

SETTINGS AND DESIGN:

A case-control study.

MATERIALS AND METHODS:

Eighty-one randomly selected couples with unexplained three or more RSAs and a control group of 97 couples with live birth belonging to the same ethnic background, referred to the Gynaecology Department, KEM Hospital were included in the case-control study. Serological HLA A and B typing was done followed by molecular subtypes, defined using PCR-SSOP technique for HLA A, B, and C in 40 couples and DRB1* and DQB1* in 28 couples which were then compared with appropriate case 46 and 88 controls.

RESULTS:

Serologically A3 (15.43% vs. 4.43%; odds ratio (OR) = 4.34; P = 0.0002) and B17 (25.3% vs. 11.34%; OR = 3.49; P = 0.0001) were increased. Haplotype A1-B17 was significantly increased. Molecular subtyping revealed that A*030102 (11.25% vs. 4.34%; OR = 3.00; P = 0.07), B*5701 (11.25% vs. 1.08%; OR = 13.10; P = 0.003), Cw*120201 (25% vs. 4.34%; OR = 10.50; P = 2.05E-05), HLA DRB1*030101 (17.85% vs. 3.40%; OR = 7.6; P = 0.0001), DRB1*150101 (32.14% vs. 13.63%; OR = 4.8; P = 0.0003), and DQB1*060101 (35.71% vs. 29.34%; OR = 2.3; P = 0.004) were significantly increased in patients. A differential association was noticed when compared with reported world RSA patients.

CONCLUSION:

The HLA alleles A*030101, B*5701, Cw*120201, DRB1*030101, and DRB1*150101 as well as their associated ancestral haplotype may play a significant role in development of RSA in India.

Novel alleles of HLA-DQ and -DR loci show association with recurrent miscarriages among South Indian women

BACKGROUND In this study, recurrent miscarriages (RMs) are defined as loss of two or more clinically detectable pregnancies before 20 weeks of gestation. HLA has been thought to play a role in RM. However, the results of earlier studies on the role of different human leucocyte antigen (HLA) genes were conflicting and inconclusive. In the present study, we investigate HLA genes (HLA-DRA, HLA-DRB1, HLA-DQA1 and HLA-DQB1) in RM couples with unknown etiology and normal couples. METHODS Blood samples from 143 RM couples and 150 control couples were analyzed, firstly to validate previously reported association studies and secondly to explore whether any novel alleles or haplotypes specific to Indian populations can be observed to be associated with RM. HLA typing was carried out by DNA sequencing. RESULTS Results suggest an association of the DQB1*03:03:02 allele with RM (odd ratio = 2.66; p(c) = 0.02; confidence interval = 1.47-4.84). Haplotypes of the DQA1 and DQB1 risk alleles also showed a significant association with RM, albeit not after Bonferroni correction for multiple comparisons. CONCLUSIONS HLA-DQB1 appears to have a strong involvement in the manifestation of RM in this population from South India. The current genetic analysis of RM and control couples not only highlights the genes exhibiting a strong etiological role but also reflects the protective nature of some HLA genes against RM. Nevertheless, most of these alleles/haplotypes were not those that are implicated in RM in other ethnic backgrounds, and hence require further validation in other populations of India, from different ethnic and/or geographic backgrounds.

Immunological analogy between allograft rejection, recurrent abortion and pre-eclampsia - the same basic mechanism?

There are still controversies concerning the role of immunological mechanisms engaged both in recurrent abortions (RA) and pre-eclampsia (PE). According to some opinions, recurrent miscarriage is comparable to organ-specific autoimmune disease. Analysis of immune reactions shows that graft rejection shares many similar mechanisms with RA and PE. This fact allows us to conclude that rejection of transplanted alloantigenic organs and pregnancy loss have probably the same evolutionary origin. Subsets and functions of immunocompetent cells (T CD4, suppressor gammadeltaT, cytotoxic T CD8, Treg, Tr1, uterine NK cells), over-activation of innate immunity (activation of NK cytotoxic cells, macrophages, neutrophils and complement), changes of Th1/Th2 cytokine balance (IL-2, IL-12, IL-15, IL-18, IFNgamma, TNFalpha vs. IL-4, IL-10, TGFbeta), importance of HLA-G molecule, CD200/CD200R interaction, over-expression of adhesion molecules, fgl2 prothrombinase activation and stimulation of IDO and HO expression, all suggest that RA and PE are syndromes of fetal allograft rejection, and not organ-specific autoimmune diseases. According to that supposition, an analogy might exist between acute graft rejection and recurrent abortion, and between chronic graft rejection and pre-eclampsia.

Association of human leucocyte antigen sharing with recurrent spontaneous abortions

An estimated 15% of clinically recognized pregnancies abort spontaneously. Recurrent spontaneous abortion (RSA) is defined as three or more consecutive miscarriages conceived with the same partner in the absence of uterine, genetic or autoimmune abnormalities. Evidence points to human leucocyte antigens (HLA) as playing a role in the successful development of the foetus. In particular, HLA compatibility is more prevalent in couples experiencing reproductive failure, especially RSA couples, compared to fertile couples. According to the immunological hypothesis, an adequate immune response is necessary for proper implantation of the embryo; conversely, a depressed response of maternal lymphocytes to the stimulation by paternal antigens because of HLA sharing can result in disorders, such as RSA. The genetic hypothesis implicates homozygosity for recessive lethal alleles in linkage disequilibrium with specific HLA haplotypes. The specificity of HLA alleles or haplotypes responsible for or linked to other RSA susceptibility genes remains unclear. In this study, we identified 40 observational studies (32 case-control, five cohort, one cross-sectional, one case series and one basic science) that examined the associations between HLA and RSA, focusing on HLA allele couple and maternal-foetal sharing, and the special role of HLA-G. We sought to identify consistent findings among studies examining similar questions. Evidence remains divided concerning the role of HLA allele couple sharing. Of major concern is the focus of many studies on couple sharing as a proxy measure of maternal-foetal sharing. Therefore, adequately powered studies are needed, which employ standard case definitions and reproducible methodologies to directly assess the role of maternal-foetal HLA sharing on the risk of RSA.

Transmission of Parentally Shared Human Leukocyte Antigen Alleles and the Risk of Preterm Delivery

OBJECTIVE

Our objective was to examine our hypothesis that the transmission of parentally shared human leukocyte antigen (HLA) alleles to offspring increases the risk of preterm delivery.

METHODS

A population-based family study with participating children and their parents was conducted in Kaiser Permanente Medical Care Program, an integrated healthcare delivery system, in the Northern California Region. A total of 234 participants from 78 families with early preterm deliveries (35 weeks of gestation or greater) and 60 participants from 20 families with full-term births were included in the study. Buccal cells were collected from the first-born preterm cases and their parents to determine HLA-B (class I) and DRB1 (class II) types and the transmission of parental alleles to the offspring. The buccal samples were also collected from full-term deliveries to rule out possible segregation distortion at the studied HLA loci.

RESULTS

Compared with the expected transmission probability based on Mendel's laws (25%), transmission of parentally shared HLA-B or DRB1 alleles from both heterozygous parents to offspring (48% of 23 heterozygous parents) was associated with a more than 5-fold increased risk of preterm delivery (odds ratio 5.5; 95% confidence interval 1.2-51). Transmission of parentally shared HLA alleles from heterozygous mothers (83%) appears to be more important in the etiology of preterm delivery than transmission from fathers (57%). The transmission pattern of parentally shared HLA alleles in our full-term controls was almost identical to the expected pattern based on Mendel's laws and demonstrated no segregation distortion at those HLA loci.

CONCLUSION

Our findings provide evidence that the transmission of parentally shared HLA alleles may be an underlying mechanism for preterm delivery.

Role of HLA in congenital heart block: susceptibility alleles in children

Congenital heart block (CHB) is a syndrome of uncertain pathogenesis leading to cardiac conduction disturbances in the foetus and newborns. It has been proposed that maternal antibodies transmit immunological injury in the developing foetal heart, thus causing irreversible damage of the atrioventricular node, leading to third-degree atrioventricular block. However, some genetic or environmental factors may also be involved. We have searched for genetic markers that play a role in immune response and that would be pathognomonic for the disease, either in mothers by regulating their immune response or in children by affecting antigen presentation and target for the maternal immune response. We have compared HLA class I and II alleles of the children with their mother and with healthy individuals and searched for HLA markers that would be emphasized in children. We have shown that particular DQ alleles in the child predispose to CHB, perhaps serving as antigen-presenting molecules on site. In addition, the HLA-Cw3 allele is involved, although its function remains to be clarified. In our results, children with CHB were often identical to their mothers in alleles of DRB, DQA and DQB loci, thus affecting foetomaternal recognition and suggesting that cell-mediated mechanisms could be involved in the pathogenesis.

Analyses of HLA-DQ alleles in recurrent spontaneous abortion (RSA) couples

PROBLEM

The influence of HLA sharing on pregnancy outcome is controversial. In renal transplantation, HLA-DQB1 donor-recipient mismatches have been shown beneficial for long-term transplant success. Since pregnancy is defined as Nature's allograft, we investigated the relevance of HLA-DQ mismatching in normal reproducing couples compared to couples experiencing RSA.

METHOD

Unexplained RSA couples referred to our laboratory for immunological testing were classified by immunological findings and obstetrical history. Primary RSA couples shared > or = 2 HLA-A, B, or DR antigens, had no cytotoxic anti-paternal antibodies, and no gestation beyond 20 weeks. Secondary RSA couples had cytotoxic anti-paternal antibodies and RSA after a live birth. HLA-DQA1 and DQB1 alleles were identified by PCR-SSP.

RESULTS

No differences in DQA1 and DQB1 mismatch were observed among RSA patients and controls. DQA1-DQB1 haplotype mismatches were not different among the three groups of couples.

CONCLUSIONS

In contrast to renal transplant, HLA-DQ incompatibility did not differ among RSA couples compared with successful reproducing couples.

Unexpected HLA haplotype sharing in dizygotic twin pairs discordant for rheumatoid arthritis

Dizygotic twins are generally believed to be no more genetically similar than sibs born from separate pregnancies. In the present study, a panel of 93 dizygotic twin pairs discordant for rheumatoid arthritis were typed for HLA-A, -B, -Cw, and -DR antigens. HLA haplotype sharing identical by descent between the twins showed a trend towards increased sharing of both HLA haplotypes; this increased sharing was statistically significant when the female/female twin pairs were considered separately. In contrast, the pattern of HLA haplotype sharing in sib pairs (n = 128) was consistent with a 1:2:1 ratio of 2, 1, or 0 haplotypes shared. An analysis of 16 normal dizygotic twin pairs was consistent with these results raising the possibility that dizygotic twins in general are genetically more similar at the HLA complex than sibs born from separate pregnancies.

Expression of human leukocyte antigens in patients with autogenic and allogenic circulating antisperm antibodies

Circulating antisperm antibodies have been shown to have an adverse effect on a couple's ability to achieve fertilization. This study investigated the HLA class II pattern in couples with infertility associated with antisperm antibodies. Forty-nine couples with significant circulating antisperm antibodies confirmed with immunofluorescence technique and 15 control couples had HLA class II-DR, DQ typing. The Terasaki lymphotoxicity test was used. In women with antisperm antibodies, HLA class II haplotypes DR4, DR6, and DQW3 were more common than in the control group. For the men, DR6 and DQ7 were more common in those with antisperm antibodies, than in controls. With sharing of the haplotypes by the couples, DR4, DR6, and DQ7 were more common in couples with antisperm antibodies, but deficient in DQW3. HLA class II-DR4, DR6, and DR7 sharing in couples and deficiency of DQW3 may be associated with circulating antisperm antibody production.

Maternal HLA class II alleles predispose to pregnancy losses in Danish women with recurrent spontaneous abortions and their female relatives

PROBLEM

If damage to the trophoblast mediated through autoimmune mechanisms is responsible for recurrent spontaneous abortions (RSA), maternal class II HLA antigens might be expected to be involved. We wanted to evaluate the impact of these antigens on pregnancy outcome in RSA women and their relatives.

METHOD

HLA-DR and -DQ typing using RFLP and PCR-SSP methods was carried out in 234 Danish women with unexplained RSA and 360 controls. The HLA-DR types were correlated to outcome of the next pregnancy in 94 patients. Sisters, brothers, and wives of brothers of 146 consecutive patients were HLA typed and their pregnancy outcomes were correlated to the HLA-DR types.

RESULTS

HLA-DR1/Br and -DR3 were each significantly increased in women with at least four previous pregnancy losses (both P-values < 0.05 after correction for multiple comparisons). In the prospective study, 62% of the HLA-DR1/Br and/or -DR3 positive patients miscarried the next pregnancy compared with only 29% of those negative for both allogenotypes (P = 0.025). The family studies indicated that female relatives of RSA patients had a greater risk (odds ratio = 5.0, 95% CI = 2.0-11.0) of pregnancy losses when positive for HLA-DR1/Br and/or -DR3 than those negative for the allogenotypes.

CONCLUSIONS

Maternal HLA-DR allogenotypes DR1/Br and -DR3 or closely linked genes seem to predispose to pregnancy losses in RSA patients and their first degree relatives.

Maternal HLA class II allogenotypes are markers for the predisposition to fetal losses in families of women with unexplained recurrent fetal loss

The HLA allogenotypes DR1/Br, DR3 and DR10 (entitled risk HLA markers) have been reported as being genetic markers for the predisposition to experience unexplained recurrent fetal losses. The aim of the study was to determine whether the putative risk HLA markers might also be markers for the risk of pregnancy loss in sisters and wives of brothers of women with unexplained recurrent fetal losses. Information concerning pregnancy outcomes among the relatives of 146 consecutive women with unexplained recurrent fetal losses was collected. Ninety-five of the full sisters, 69 of the full brothers and 50 of the wives of the brothers were HLA typed. Sisters who had experienced at least one previous pregnancy loss (affected women) shared more HLA haplotypes with the proband than unaffected sisters, when the proband was positive for the risk markers (P = 0.02). More affected than unaffected sisters and brothers' wives were positive for the risk markers (P < 0.005 and P < 0.03; respectively). The lowest estimate of the odds ratio for experiencing pregnancy loss among sisters and brothers' wives who were positive compared with those negative for the risk markers was 3.5 (95% credible interval = 1.9-5.8). It is concluded that maternal DR1/Br, DR3 and DR10 allogenotypes seem to be genetic markers for the risk of pregnancy loss among relatives of women with unexplained recurrent fetal losses. The pattern of inheritance suggests a polygenic mode of inheritance with alleles linked to the risk HLA markers interacting with non-HLA linked genes expressed on the fetus or the trophoblast.

HLA class II alleles confer susceptibility to recurrent fetal losses in Danish women

HLA-DR and -DQ typings were performed by a combination of RFLP and PCR-SSP techniques in 234 Danish women with at least three consecutive unexplained fetal losses (recurrent fetal losses) and 360 controls and the DRB1, DQA1 and DQB1 alleles were deduced. In the total group of patients, the frequency of no DRB1-DQA1-DQB1 haplotype was significantly increased compared with controls. In the subgroup of 97 women with four or more fetal losses (multiple fetal loss group), the frequency of women carrying the DRB1*0101, DQA1*0101, DQB1*0501; DRB1*0102, DQA1*0101, DQB1*0501 and DRB1*0103, DQA1*0101, DQB1*0501 haplotypes or the DRB1*0301, DQA1*0501, DQB1*0201 haplotype were significantly increased compared with controls (RR = 2.1; pc < 0.05 with regard to former three haplotypes combined and RR = 2.2; pc < 0.05 for the latter). The frequency of women with at least one of the four haplotypes was significantly (p < 0.002) increased with the number of previous fetal losses in the women's history. Analysis of the DQA1 and DQB1 phenotypes in women with at least four fetal losses showed that DQA1*0501 and DQB1*0501 were increased compared with controls (RR = 1.9; pc < 0.05 and RR = 2.2; pc < 0.025, respectively). Analysis of DRB1-DQA1-DQB1/DRB1-DQA1-DQB1 genotypes suggested that genotypes comprising both DQA1*0501 and DQB1*0501 alleles (in trans) exhibited a higher RR for experiencing at least four fetal losses (RR = 3.4, p = 0.002) than each of the alleles did alone.(ABSTRACT TRUNCATED AT 250 WORDS)