[Ovarian autoimmunity and ovarian pathologies: antigenic targets and diagnostic significance]

The preclinical evaluation of immunocontraceptive vaccines based on canine zona pellucida 3 (cZP3) in a mouse model

BACKGROUND

Stray dogs are the reservoirs and carriers of rabies and are definitive hosts of echinococcosis. To control the overpopulation of stray dogs, zona pellucida 3 (ZP3), a primary receptor for sperm, is a potential antigen for developing contraceptive vaccines. To enhance the immune responses and contraceptive effects of canine ZP3 (cZP3), dog gonadotropin-releasing hormone (GnRH) and a T cell epitope of chicken ovalbumin (OVA) were selected to construct two fusion proteins with cZP3, ovalbumin-GnRH-ZP3 (OGZ) and ovalbumin-ZP3 (OZ), and their contraceptive effects were evaluated in mice.

METHODS

The synthesized DNA sequences of OGZ and OZ were cloned into plasmid pET-28a respectively. The fusion proteins OGZ and OZ were identified by SDS-PAGE and Western blot. Mice were immunized with OGZ, OZ and cZP3, and the infertility rates were monitored. Mice immunized with mouse ZP3 (mZP3) or adjuvant alone were used as positive control and negative control, respectively. cZP3- and GnRH-specific antibodies (Abs) were detected by ELISA. The bindings of the Abs to oocytes were detected by indirect immunofluorescence assay. The paraffin sections of mice ovaries were observed under microscope for analyzing pathological characteristics.

RESULTS

SDS-PAGE and Western blot analyses showed that the two fusion proteins OGZ and OZ were correctly expressed. ELISA results showed that OGZ vaccine induced both cZP3- and GnRH-specific Abs, and OZ vaccine induced cZP3-specific Ab, which lasted for up to 168 days. The levels of follicle stimulating hormone (FSH) and estradiol (E2) in sera were significantly decreased in OGZ immunized mice. Indirect immunofluorescence results showed that Abs induced by cZP3 and mZP3 could bind to the mouse ZP and dog ZP each other. Compared with the adjuvant group, all vaccine immunized groups significantly decreased the fertility rate and mean litter size. Interestingly, the fertility rate in OGZ-immunized group is the lowest, and only 1 mouse out of 10 mice is fertile. Histological analysis of murine ovarian sections indicated that most of the infertile mice in the immunized groups lacked mature follicles as well as accompanied by inflammatory infiltration. Meanwhile, immunization with OGZ decreased the number of corpora lutea in the infertile mice.

CONCLUSIONS

The fusion protein OGZ resulted in the lowest fertility rate and the least mean litter size in the immunized mice. OGZ might be a promising antigen for developing a new contraceptive vaccine for stray dog controlling.

The effects of GM-CSF and IL-5 as molecular adjuvants on immune responses and contraception induced by mZP3 DNA vaccination

PROBLEM

Various approaches have been developed to improve the antibody response of zona pellucida glycoprotein-3 (ZP3) vaccination. In this study, we investigated whether GM-CSF and IL-5 can be used as cytokine adjuvants to increase the humoral immune response generated by mouse ZP3 (mZP3) DNA vaccine.

METHOD OF STUDY

Mice in experimental group were injected by GM-CSF 4 days before the co-immunization of IL-5 and mZP3 DNA vaccine. The contraception and the correlation with humoral and cellular immune responses were analyzed after immunization and mating. The effect of cytokine adjuvant on the maturation of DCs was evaluated.

RESULTS

Co-immunization of GM-CSF and IL-5 with mZP3 DNA vaccine induced the highest level of serum IgG and IL-4 expression in CD4(+) T cells. Importantly, this strategy reduced mice fertility without disrupting normal ovarian morphology. GM-CSF enhanced the maturation of DCs evidenced by up-regulating the expression of MHC-II and CD86.

CONCLUSION

GM-CSF and IL-5 co-administration enhanced humoral immune responses to mZP3, and this may be a potential strategy for development of immunocontraceptive vaccine.

Intranasal co-delivery with the mouse zona pellucida 3 and GM-CSF expressing constructs enhances humoral immune responses and contraception in mice

Granulocyte-monocyte colony-stimulating factor (GM-CSF) regulates the function of antigen-presenting cells (APCs) and has been broadly used as the adjuvant. Here, we tested whether intranasal delivery of GM-CSF can improve the contraception of mouse zona pellucida 3 (mZP3) DNA vaccine. Our results showed that co-administration of GM-CSF and mZP3 DNA vaccine increased the levels of secretory IgA (sIgA) and IgG antibodies in vaginal washes and serum, respectively. Co-administration enhanced Th2 responses through improving the maturation of dendritic cells. Importantly, GM-CSF significantly reduced the fertility rate and mean litter size induced by mZP3 DNA vaccine alone without interfering the normal follicular development. These data suggest that GM-CSF could be used as adjuvant to develop immunocontraceptive vaccine.

Autoantibodies to mesothelin in infertility

BACKGROUND

According to extensive epidemiologic data, infertility is associated with increased ovarian cancer risk. Previous studies showed that both women with infertility and those with ovarian cancer have autoantibodies to ovarian antigens. The objective was to determine if women with infertility have antibodies to mesothelin, a well-characterized ovarian cancer antigen.

METHODS

Sera were obtained from women with infertility (n = 109), ovarian cancer (n = 28), benign ovarian tumors or cysts (n = 24), and from healthy women (n = 152). Infertility included those with a risk for ovarian cancer; endometriosis (n = 23), ovulatory dysfunction (n = 17), premature ovarian failure (POF; n = 25) and unexplained infertility (n = 44). Sera were assayed for mesothelin antibodies and for circulating mesothelin antigen by immunoassay and compared with assay control sera (n = 16) to determine a positive result.

RESULTS

Mesothelin antibodies were significantly more frequent in women with prematurely reduced ovarian function including ovulatory dysfunction (59%), ovarian failure (44%) and unexplained infertility (25%) compared with controls. In contrast, women with endometriosis, who also have a high risk for ovarian cancer, did not have mesothelin antibodies. Serum levels of mesothelin were rarely elevated in women with infertility but were high in most patients with ovarian cancer.

CONCLUSIONS AND IMPACT

We show for the first time that antibodies to mesothelin, a well-characterized ovarian cancer antigen, occur in some women with epidemiologic risk for ovarian cancer. The results suggest it may be possible to identify which women with infertility have ovarian cancer risk.