L’impact du stress dans le dialogue materno-fœtal : une approche immunologique

Implications from early life stress on the development of mouse ovarian follicles: Focus on oxidative stress

AIM

The early life stress has significant long-term effects on the development of the offspring. This study was undertaken to verify if maternal separation as a stressor agent affects the oxidative status and developmental competence of mouse pre-antral follicles (PF) during in vitro culture period.

METHODS

Female litters of National Medical Research Institute mice were divided into two groups: maternally separated group (MS), separated from the mothers for 6 h per day from postnatal days 2-16; and the rest considered as the control group, which left undisturbed over the 14 days. The litters were sacrificed and the ovarian tissue was harvested to isolate the PF. The PF were in vitro cultured up to 12th day when ovulation was induced. The developmental parameters and oxidative status (i.e., total antioxidant capacity and Malondialdehyde levels, as well as the activities of superoxide dismutase, glutathione peroxidase and catalase) were assessed.

RESULTS

The rates of survival, antrum formation, ovulation and oocyte maturation of PF derived from the MS group were significantly lower compared with those of the control group. Furthermore, the Malondialdehyde level of the MS group was significantly higher than that of the control group. By contrast, the total antioxidant capacity level was lower in the MS group with respect to the control group. Also, the activity of superoxide dismutase, glutathione peroxidase and catalase of PF, derived from the MS group, was significantly lower compared with those of the control group.

CONCLUSION

Early life stress damages the developmental competence of mouse PF through induction of oxidative stress.

Leukemia inhibitory factor gene mutations in the population of infertile women are not restricted to nulligravid patients

OBJECTIVE

Leukemia inhibitory factor (LIF) is one of the key cytokines in the embryo implantation regulation. We investigated the prevalence of the LIF gene mutations in the population of infertile women that consisted of nulligravid and secondary infertile patients.

STUDY DESIGN

We designed a LIF gene mutation screening method that is based on the Temperature Gradient Gel Electrophoresis (TGGE). The population to screen consisted of 176 infertile women including group A of 147 nulligravid women and group B of 29 women with secondary infertility that had a history of either miscarriage or an ectopic pregnancy but no live births. The control population was comprised of 75 healthy fertile subjects. The groups of fertile controls and infertile patients were compared for statistically significant differences using the t-test.

RESULTS

Six potentially functional LIF gene mutations, the G to A transitions at the position 3400 leading to the valin to methionin exchange at codon 64 (V64M) in the AB loop region of the LIF protein, were detected. All of the six positive women were infertile. Four of them were nulligravid and two of them had history of spontaneous conception followed by early miscarriage. No positive TGGE samples were identified in the control group, which means that the frequency of functionally relevant mutations of the LIF gene in infertile women is significantly enhanced in comparison with controls (P<0.05, t-test).

CONCLUSION

The results suggest that the LIF gene mutations affect fertility. Even though they occur infrequently, their impact on molecular events during early phases of pregnancy should be further established.

Histamine regulates placental cytokine expression--in vivo study on HDC knockout mice

Successful pregnancy is closely related to polarization toward a Th2 type immune response. As histamine is known to initiate Th2 dominance during inflammatory processes we raised the question whether histamine has any effect on the actual tuning of proper cytokine balance for the proceeding of the gestation. Histamine has multiple functions in the process of pregnancy, different studies have shown the direct and/or indirect presence of histamine action in the placenta as well. As HDC is the unique histamine producing enzyme in eukaryotes, we used HDC (so endogenous histamine)-deficient knockout mice as reliable model for studying histamine-related processes in vivo. We examined the placental histamine content and the expression of histamine receptors and Th1/Th2/Th3 type cytokines in the placenta. We showed for the first time the influence of histamine on the orchestrated regulation of placental cytokine expression. In the absence of local histamine the cytokine balance is shifted toward Th1 types at the maternal-placental interface, threatening pregnancy. We also measured splenic lymphocyte subpopulation ratios in pregnant and non-pregnant mice and found that in pregnancy they are independent of the presence of histamine.

Role of the leukemia-inhibitory factor gene mutations in infertile women: the embryo-endometrial cytokine cross talk during implantation--a delicate homeostatic equilibrium

Locally secreted cytokines of both the embryonic and the endometrial origin control the implantation process. The defects in their signaling that lead to unfavorable environment within the uterus may cause embryo implantation failure. The leukemia inhibitory factor (LIF), interleukin-11 (IL-11) as well as IL-12/IL-15/IL-18 system are regarded to be important signaling vectors. LIF plays an essential role in the preimplantation embryo development and the blastocyst implantation and its gene mutations in women contribute to the implantation failure and subsequent infertility. IL-11 signaling has been shown to be required for the uterine decidualization response as well as for the hatching and attachment of blastocysts. The IL-12/IL-15/IL-18 system interacts with endometrial leukocytes, particularly with NK cells, and influences directly the local angiogenesis and tissue remodeling. Differences in the levels of endometrial leukocytic subpopulations and in the patterns of intra-uterine cytokine concentrations that are observed between fertile and infertile women contribute to infertility probably by affecting the embryonic maternal dialogue during the implantation and early placentation period. Focusing on this cross talk promises to open new era in assisted reproduction techniques that will be based on diagnostics of missing signaling molecules and impairments of uterine receptivity as well as on therapeutic applications of individualized embryo culture and transfer media.