Intervention in B7 (CD80/CD86)/B7-ligand (CD28/CTLA-4) pathways is an effective way of preventing unwanted immune responses, such as allograft rejection. Pregnancy maintenance represents maternal tolerance to the fetal allograft, which is accompanied by a type 2 helper cell (Th2) bias at the maternalfetal interface. Here, the costimulatory signal of CD86 was selectively blocked, and that of CD80 was kept unimpaired by administration of anti-murine CD86 monoclonal antibody at the early gestational stage in abortion-prone CBA/J3DBA/2 matings and normal pregnant CBA/J3BALB/c matings. It was demonstrated that in vivo blockade of CD86 costimulation could suppress maternal immune attack to the fetus by shifting cytokines from Th1 predominance to Th2 bias at the maternal-fetal interface, and expanding peripheral CD41CD251 regulatory T cells, which play an important role in the development and maintenance of maternal-fetal tolerance. Furthermore, the expression of CD28 and its ligands CD80/CD86 on peripheral lymphocytes was down-regulated, whereas that of CTLA-4 was up-regulated, which might facilitate the suppressive effect of CD4+CD25- regulatory T cells on the alloreactive T cells. The maternal-fetal immunotolerance induced by CD86 blockade decreased fetal resorption in CBA/J3DBA/2 matings, but did not affect normal pregnant CBA/J3BALB/c matings. These results suggest that selective blockade of CD86 costimulation leads to maternal immune tolerance to embryo antigen, and might contribute to a rational immunoregulatory regimen for recurrent spontaneous abortion.

CD28/CTLA-4 interactions with their specific B7-ligands (CD80 and CD86) play a decisive role in antigenic and allogenic responses. Recently, experimental transplant studies demonstrated that donor-specific tolerance was achieved by blocking these interactions. However, the role of blockade of CD28/B7 costimulatory pathway in the maintenance of materno-fetal tolerance has received little attention. In the present study, abortion-prone CBA/J females mated with DBA/2 males were administered with anti-CD80 and anti-CD86 monoclonal antibodies (mAbs) on day 4 of gestation (time of murine implantation). We demonstrated that the combined use of anti-CD80 and anti-CD86 mAbs induced maternal tolerance to the fetus in the abortion-prone CBA/J mice, and displayed expansion of the maternal CD4+CD25+ regulatory T cell population and up-regulated expression of CTLA-4, suggesting an active mechanism of regulatory T cells in suppressing maternal rejection to the fetus. In addition, the anti-CD80/86 mAbs treatment enhanced Th2 and reduced Th1 cytokine production in mice, implying that the development of Th2 cells might contribute to maternal tolerance to her fetus. Together, these findings indicated that blocking CD80 and CD86 enhanced maternal tolerance to her fetus in mice by increasing regulatory T cell function and skewing toward a Th2 response. Our data might provide an enhanced understanding of the maternal-fetal immune relationship and be helpful in clinical trials for immunotherapy of recurrent spontaneous abortion.

More than 70% of decidual lymphocytes are NK cells characterized by CD56brightCD16- phenotype, but the mechanisms by which these NK cells are recruited in the decidua are still almost unrevealed. In this study, we first analyzed the transcription of 18 chemokine receptors in the first-trimester decidual CD56brightCD16- NK cells. Among these receptors, CXCR4 and CXCR3 were found highly transcribed, and the expression of CXCR4 was verified in most of the decidual CD56brightCD16-NK cells by flow cytometry. The first-trimester human trophoblasts were found expressing CXCL12/stromal cell-derived factor 1, the specific ligand of CXCR4, by way of in situ hybridization and immunohistochemistry. The primary cultured trophoblast cells were also found to secrete stromal cell-derived factor 1-spontaneously, and its concentration was 384.6-90.7pg/ml after the trophoblast cells had been cultured for 60 h. All of the ligands for CXCR3 were below the minimal detectable concentration when trophoblast cells were cultured for up to 48 h. Both recombinant human SDF-1-and supernatants of the cultured trophoblast cells exhibited chemotactic activity on decidual CD56brightCD16- NK cells. Our findings suggest that human first-trimester trophoblast cells produce CXCL12, which in turn chemoattracts decidual CD56brightCD16- NK cells. This activity could contribute to the recruitment mechanism of decidual lymphocytes, especially CD56brightCD16-NK cells, in decidua, and may be used at a local level to modulate the immune milieu at the materno-fetal interface.

To show that an anti-human chorionic gonadotrophin-β (hCGβ) antibody response can be induced by inoculating Lb. Expressing hCGβ through diVerent mucosal pathways in mice of two strains, female BALB/c and C57BL/6 mice were immunized via vaginal, oral or nasal routes with 108, 109, and 1010 Lb.hCGβ (a recombinant Lactobacillus expressing hCGβ). The mice were immunized twice with a booster in study week 3. An indirect ELISA was used to determine anti-hCGβ IgG and IgA antibodies in vaginal lavage and serum, obtained from the 2nd to 8th week after the primary immunization. Flow cytometry was used to analyze the lymphocyte proliferation from these tissues, 1 week after the primary immunization. The hCGβ antigen-speciWc antibody-secreting cells of spleen, uterus, and vagina were evaluated by enzyme-linked immunospot assay (ELISpot), 2 weeks after the booster. The analysis showed that 109 and 1010 Lb.hCGβ inoculations induced similar anti-hCGβ antibody responses, while the three mucosal pathways induced similar antibody responses. The antiserum obtained after boosters with 109 and 1010 Lb. hCGβ was able to neutralize more than 100 ng/ml hCGβantigen, both in BALB/c and C57BL/6 mice. The highest antibody titer induced by vaginal mucosal immunization was stronger than that obtained via the other mucosal pathways. The B cells in the vagina appeared to proliferate after vaginal immunization (P <0.05). The numbers of anti-hCGβ IgG and IgA antibody-secreting cells in the uterus and vagina were greater than in the spleen. Therefore, the vaginal mucosal route appears to be a better immunization pathway to induce higher anti-hCGβ antibody levels in the reproductive tract.

BACKGROUND: Chemokines play an important role in the pathogenesis of endometriosis. In the present study, the transcription of 18 chemokine receptors in eutopic endometrium and ectopic tissue with endometriosis was first analysed by RT–PCR. Dioxin, an air pollutant, and estrogen are reported to be associated with endometriosis. The regulatory mechanisms of dioxin and estrogen in the expression of CXCR1/IL-8 in the corresponding cells will help in elucidating roles of the chemokine in the aetiology of endometriosis. METHODS AND RESULTS: CXCR1, a type of chemokine receptor, was over-expressed in endometriotic tissue. The high translation of the receptor and its ligand, interleukin (IL-8), in endometriotic tissue was then demonstrated by immunochemistry. Estradiol and 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) alone inhibited expression of CXCR1, whereas the combination of estradiol with TCDD up-regulated the expression. TCDD promoted IL-8 secretion by human pelvic mesothelial cells (HPMC), and 17 -estradiol magnified the stimulatory effect. Both 17-estradiol and TCDD alone inhibited IL-8 secretion of U937 (a cell line of monocyte), but combination of 17-stradiol and TCDD had no further inhibitory effect. The co-culture of endometrial stromal cells (ESC) with HPMC produced more IL-8 than respective or total production of either of the cells alone, and estradiol played a synergistic stimulatory role with TCDD in IL-8 secretion of the co-culture. Interaction of HPMC and the monocytes significantly stimulated IL-8 secretion, suggesting a main resource of IL-8 in peritoneal cavity with endometriosis. TCDD promoted IL-8 secretion by HPMC-U937 co-culture, but exerted a contrary effect for IL-8 secretion when combined with estradiol. CONCLUSION: Estradiol and TCDD in the peritoneal cavity can lead to a persistent and serious inflammation, which gives a new insight into the interactions of estrogen and TCDD in endometriosis.