Antiviral factors and type I/III interferon expression associated with regulatory factors in the oral epithelial cells from HIV-1-serodiscordant couples

Abstract

Individuals who remain HIV-seronegative despite repeated unprotected exposure to the virus are defined as exposed seronegative (ESN) individuals. Innate and adaptive immunity, as well as genetic factors, provide ESNs with important advantages that allow for low infection susceptibility. The majority of HIV-1-infected individuals undergo antiretroviral therapy, which can decrease the level of HIV-1 exposure in ESNs. We analyzed type I interferon (IFN)-related antiviral and regulatory factors in peripheral blood mononuclear cells (PBMCs) and oral epithelial cells from serodiscordant couples. Our findings revealed that ESNs did not induce the expression of antiviral factors (APOBEC-3G, TRIM5-α, SAMDH1, STING, TBk1) or regulatory factors (Trex, Foxo3, Socs3, IL-10) in PBMCs, unlike their HIV-1-infected partners. In contrast, ESNs upregulated APOBEC-3G and type I/III IFNs (IFNs-α,-β/-λ) in oral mucosal epithelial cells similar to their HIV-infected partners. The serodiscordant groups exhibited an increased expression of type I IFN-induced regulators, such as Trex and Foxo3, in oral epithelial cells. TLR7, TLR8 and TLR9 were expressed in oral epithelial cells of both ESNs and HIV-1-infected subjects. These findings revealed evidence of antiviral factors, type I/III interferon and regulatory factor expression only in the oral mucosal compartment of ESNs, while HIV-1-infected partners systemically and oral mucosal expressed the antiviral profile.

Figure 1. Increased antiviral restriction factor expression in PBMCs of HIV-1-infected partners from serodiscordant couples.

Real-time PCR analysis of mRNA expression levels of antiviral factors, such as (A) A3G, TRIM-5α, SAMDH1, (B) STING, TBk1, and IFN-β in PBMCs of healthy controls (HCs, n = 15), exposed seronegative (ESNs, n = 14) individuals and the corresponding HIV-1 infected partners (n = 13). The data represent the median values. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.

Figure 2. Expression of regulatory factors in PBMCs of serodiscordant couples.

The mRNA expression levels of Trex, Foxo3, Socs3 and IL-10 in PBMCs of healthy controls (HCs, n = 14), exposed seronegative (ESNs, n = 11–15) individuals and the corresponding HIV-1 infected partners (n = 11–15) were evaluated by real-time PCR. The data represent the median values. *p ≤ 0.05, ***p ≤ 0.001.

Figure 3. The upregulation of antiviral factor expression in the mucosal oral epithelial cells of serodiscordant couples.

The mRNA expression levels of (A) A3G, Trex, Foxo3 and (B) IFN-α, IFN-β and IFN-λ are shown. (C) Correlations between ESN IFN-β expression and antiviral factors are presented. Cells from buccal washes were obtained from healthy controls (HCs, n = 10–14), exposed seronegative individuals (ESNs, n = 11–15) and HIV-1-infected partners (n = 11–15), and assessed by real-time PCR. The data represent the median values. *p ≤ 0.05.

Figure 4. Increased TLR7, TLR8 and TLR9 expression in the mucosal oral epithelial cells from serodiscordant couples.

The antiviral mRNA expression levels in cells from buccal washes from healthy controls (HCs, n = 5–10), exposed seronegative individuals (ESNs, n = 13) and HIV-1-infected partners (n = 13) were evaluated by real-time PCR. The data represent the median values. *p ≤ 0.05.