The Influence of Constitutive Cervical Interleukin-17 Cytokines on Hiv-1 Infection Transmission Outcomes

Abstract

Background: Human Immunodeficiency Virus (HIV)-1 infection is still a major global health concern, with women and young girls in the sub-Saharan region disproportionately infected. The natural transmission of HIV primarily occurs through mucosal tissues, which also serv as the major reservoir for its replication. It is therefore important to understand the initial interplay between HIV-1 and mucosal immune factors which will steer prevention and curative strategies. Interleukin (IL)-17A, C, E, and F cytokines have been seen to shape immune responses to microbial pathogens in the female genital tract by maintaining mucosal integrity and enhancement of other immune responses. However, their role in HIV-1 infection is not well known. Aim: To quantify constitutive expression of IL-17A, C, E, and F cytokines in the cervical mucosa and assess their influence on HIV-1 infection outcomes. Methodology: This exploratory cross-sectional study conveniently recruited thirty-six (36) HIV-1 seronegative female participants, aged 18-60 years, with a mean age of 47.05 years, who were undergoing hysterectomy at Kenyatta National Hospital between January and August 2024 with no known cancer of the female genital tract at the time of surgery. The participant’s demographic data was collected and recorded in a Microsoft Excel sheet. Endo and ectocervical tissue explants (n=36) were processed and IL- 17A, C, E, and F cytokines were quantified by Enzyme-Linked Immunosorbent Assay (ELISA) using the Duoset ELISA kit (R&D Systems) following the manufacturer’s protocol. Deoxyribonucleic acid (DNA) was extracted from HIV-1 BaL in-vitro infected tissue explants (n=15) to test for infectivity by real-time quantitative polymerase chain reaction (RT-qPCR) using the Qiagen Rotor-Gene Q model. Results: Age, history of hormonal contraceptive use, sexual activity, and parity did not seem to influence the constitutive expression of the cytokines across endo and ectocervical tissue explants. Though there was no significant difference in constitutive expression of IL-17A, C, E, and F cytokines between endo and ectocervical tissue explants within the same donor (n=7), their expressions varied significantly within endocervix (n=10) and ectocervix (n=33). In both endo and ectocervical tissue explants, constitutive IL- 17A was the least expressed compared to IL-17C, E, and F cytokines. Upon in-vitro exposure of endocervical tissue explants to HIV-1 BaL, though insignificant for IL-17A, C, and E, a trend of reduced expression of these cytokines was observed. There was no significant difference observed in constitutive cytokine expression between the in-vitro HIV-1 infected and uninfected ectocervical tissue explants after 24 hours of incubation, indicating that their expression did not influence in-vitro HIV-1 BaL infection outcomes. However, interestingly, an elevated expression of IL-17A cytokine expression upon HIV-1 invitro infection observed in one sample resulted in susceptibility to in-vitro HIV-1BaL infection acquisition. Overall, it was observed that these cytokines were more constitutively expressed in endocervical tissue explants compared with their expression levels in ectocervical tissue explants. Conclusion: Though there were significant differences in constitutive expression of IL-17A, C, E, and F cytokines in the endo and ectocervical tissue explants, this did not seem to influence in-vitro HIV-1 BaL infection outcomes except for the sample whose observable increase in expression of IL-17A correlated with infectivity. This seems to indicate that IL-17A expression increases the susceptibility to invitro HIV- 1 BaL infection