Semen of HIV-1-infected individuals: local shedding of herpesviruses and reprogrammed cytokine network

Abstract

Background: Semen is the main carrier of sexually transmitted viruses, including human immunodeficiency virus type 1 (HIV-1). However, semen is not just a mere passive transporter of virions but also plays an active role in HIV-1 transmission through cytokines and other biological factors.

Methods: To study the relationship between viruses and the chemokine-cytokine network in the male genital tract, we measured the concentrations of 21 cytokines/chemokines and the loads of HIV-1 and of 6 herpesviruses in seminal and blood plasma from HIV-1-infected and HIV-uninfected men.

Results: We found that (1) semen is enriched in cytokines and chemokines that play key roles in HIV-1 infection or transmission; (2) HIV-1 infection changes the chemokine-cytokine network in semen, further enriching it in cytokines that modulate its replication; (3) HIV-1 infection is associated with Epstein-Barr virus (EBV) and cytomegalovirus (CMV) compartmentalized seminal reactivation; (4) CMV and EBV concomitant seminal shedding is associated with higher HIV-1 loads in blood and seminal plasma; and (5) CMV seminal reactivation increases the seminal levels of the CCR5 ligands RANTES and eotaxin, and of the CXCR3 ligand monokine induced by gamma interferon (MIG).

Conclusions: HIV-1 infection results in an aberrant production of cytokines and reactivation of EBV and CMV that further changes the seminal cytokine network. The altered seminal milieu in HIV-1 infection may be a determinant of HIV-1 sexual transmission.

Figure 1.

Human immunodeficiency virus type 1 (HIV-1), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) loads in blood and seminal plasma. A, Correlation between the HIV-1 load in blood and seminal plasma. B, Correlation between HIV-1 blood plasma load and the CD4⁺ T-cell count. C, D, For each HIV-1–infected individual, a dotted line connects the EBV (C) and CMV (D) loads in blood and seminal plasma. Note that there is a significant positive correlation between the blood and seminal HIV-1 loads and a significant negative correlation between the HIV-1 blood plasma load and the CD4⁺ T-cell count. Note also that high CMV and EBV seminal plasma loads are often found in patients in whom blood plasma HIV-1 is undetectable.

Figure 2.

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) seminal shedding is associated with higher human immunodeficiency virus type 1 (HIV-1) loads and higher levels of seminal RANTES. A, B, HIV-1 loads in seminal (A) and blood plasma (B). C, Levels of seminal RANTES. Presented are medians and interquartile ranges. On the basis of the pattern of seminal EBV and CMV DNA, the HIV-1–infected patients were divided into 4 subgroups: (1) EBV-CMV dual shedders, (2) EBV shedders, (3) CMV shedders, and (4) nonshedders (neither EBV nor CMV). Note that the concomitant seminal shedding of EBV and CMV is associated with higher levels of HIV-1 seminal shedding, whereas CMV shedding is associated with higher levels of seminal RANTES.

Figure 3.

Cytokine spectra are different in blood and seminal plasma. Median and interquartile ranges of cytokine concentration ratios in seminal plasma and blood plasma samples (S:B) are shown for human immunodeficiency virus (HIV)–uninfected (white bars) and HIV-1–infected individuals (black bars). Asterisks denote a significant differences between the S:B ratios in HIV-uninfected versus HIV-1–infected individuals; ratios >1 or <1 indicate enrichment of a cytokine in semen or blood plasma, respectively. Note that HIV-1 infection significantly changes the compartmentalization of 11 of the 20 cytokines measured in blood and seminal plasma. Abbreviations: GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; IP, interferon gamma-induced protein; MCP, monocyte chemotactic protein; MIG, monokine induced by gamma interferon; MIP, macrophage inflammatory protein; SDF, stromal cell-derived factor; TGF, transforming growth factor; TNF, tumor necrosis factor.

Figure 4.

Two-way hierarchical cluster analysis of cytokine concentrations in blood and semen. A, Cluster analysis for human immunodeficiency virus (HIV)–uninfected individuals. B, Cluster analysis for HIV-1–infected individuals. The analysis was performed using Ward`s method on log-transformed blood and semen cytokine concentrations. Cytokine levels are expressed as color scales (blue represents low levels; red, high levels). Dendrograms under color scales classify 2 clusters according to cytokine profiles in different individuals. Dendrograms on left side reflect proximities of cytokines. Comparisons of relative cytokine levels and cytokine profiles in samples of blood and seminal plasma disclose 2 distinct cytokine profiles in both HIV-uninfected and HIV-1–infected individuals. Abbreviations: GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; IP, interferon gamma-induced protein; MCP, monocyte chemotactic protein; MIG, monokine induced by gamma interferon; MIP, macrophage inflammatory protein; SDF, stromal cell-derived factor; TGF, transforming growth factor; TNF, tumor necrosis factor.

Figure 5.

Differential effect of human immunodeficiency virus type 1 (HIV-1) infection on cytokines in blood and seminal plasma. A, Levels of cytokines in seminal plasma of HIV-uninfected (open circles) and HIV-1–infected individuals (filled circles). B, Levels of cytokines in blood plasma of HIV-uninfected (open circles) and HIV-1–infected individuals (filled circles). Values presented are medians and interquartile ranges. Asterisks denote a significant difference between median levels of a cytokine in HIV-uninfected and HIV-1–infected individuals. Interleukin (IL) 2 and interferon (IFN) γ were not detected in any sample of seminal plasma, and no granulocyte-macrophage colony-stimulating factor (GM-CSF) was found in blood plasma. The levels of RANTES in blood plasma are not presented because the aspecific spontaneous degranulation of this chemokine from platelets on venipuncture renders its measurement not representative of its specific release. Note that HIV-1 infection differently affects the production of each cytokine in blood and seminal plasma. Abbreviations: IP, interferon gamma-induced protein; MCP, monocyte chemotactic protein; MIG, monokine induced by gamma interferon; MIP, macrophage inflammatory protein; SDF, stromal cell-derived factor; TGF, transforming growth factor; TNF, tumor necrosis factor.