Induction of messenger RNA for the 70 kDa heat shock protein in HeLa cells and the human endocervix following exposure to semen: implications for antisperm antibody production and susceptibility to sexually transmitted infections.

The 70 kDa heat shock protein (HSP70) is induced in cells exposed to chemical or physical stress. HSP70 facilitates cell survival by preventing protein denaturation and incorrect assembly of polypeptides. Induction of HSP70 messenger RNA (mRNA) synthesis also inhibits transcription of genes coding for pro-inflammatory cytokines. We analyzed whether HSP70 mRNA was expressed in a cultured human cervical cell line (HeLa cells) following exposure to human semen, or in cells obtained from the endocervices of sexually active women. HeLa cells were co-cultured with a 1:50 dilution of semen from four men, with purified spermatozoa, or with cell-free seminal fluid. Endocervical swabs were obtained at mid-cycle from 53 women. HSP70 mRNA was detected in HeLa cells by a reverse transcriptase-polymerase chain reaction (RT-PCR) and analysis on agarose gels. HSP70 mRNA in cervical cells was measured by RT-PCR followed by hybridization with an HSP70-specific internal probe and detection by ELISA. Cervical IgA antibodies to HSP70 were measured by ELISA. HeLa cell-semen co-culture led in each case to induction of HSP70 mRNA. Cell-free seminal fluid and isolated motile spermatozoa also induced HSP70 mRNA when incubated individually with HeLa cells. HSP70 mRNA was detected in 28 (52.8%) of 53 endocervical cell samples obtained from women at varying times after sexual intercourse. The percentage of samples expressing HSP70 mRNA was 37.5% at <10 h, 64.3% at 10 h, 70.0% at 11 h and between 36 and 50% at later times after semen exposure. Cervical IgA antibodies to HSP70 were also detected in some women and their occurrence was highly correlated with HSP70 gene transcription (P < 0.0001). The data demonstrate that exposure to semen induces HSP70 mRNA in endocervical cells.