Human immunodeficiency virus transmission-Mechanisms underlying the cell-to-cell spread of human immunodeficiency virus

Despite the success of combined antiretroviral therapy in controlling viral load and reducing the risk of human immunodeficiency virus (HIV) transmission, an estimated 1.5 million new infections occurred worldwide in 2021. These new infections are mainly the result of sexual intercourse and thus involve cells present on the genital mucosa, such as dendritic cells (DCs), macrophages (Mø) and CD4+ T lymphocytes. Understanding the mechanisms by which HIV interacts with these cells and how HIV exploits these interactions to establish infection in a new human host is critical to the development of strategies to prevent and control HIV transmission. In this review, we explore how HIV has evolved to manipulate some of the physiological roles of these cells, thereby gaining access to strategic cellular niches that are critical for the spread and pathogenesis of HIV infection. The interaction of HIV with DCs, Mø and CD4+ T lymphocytes, and the role of the intercellular transfer of viral particles through the establishment of the infectious or virological synapses, but also through membrane protrusions such as filopodia and tunnelling nanotubes (TNTs), and cell fusion or cell engulfment processes are presented and discussed.

Immune parameters of HIV susceptibility in the female genital tract before and after penile-vaginal sex

Background

In women, most HIV infections are acquired through penile-vaginal sex. Inflammation in the female genital tract (FGT) increases the risk of HIV acquisition and transmission, likely through recruitment of HIV target cells and disruption of epithelial barrier integrity. Although sex may have important immune and epithelial effects, the impact of receptive penile-vaginal sex on the immune correlates of HIV susceptibility in the female genital tract is not well described.

Methods

STI-free heterosexual couples were recruited to the Sex, Couples and Science (SECS) Study, with the serial collection of cervical secretions (CVS), endocervical cytobrushes, blood and semen before and up to 72 h after either condomless (n = 29) or condom-protected (n = 8) penile-vaginal sex. Immune cells were characterized by flow cytometry, and immune factors including cytokines and soluble E-cadherin (sE-cad; a marker of epithelial disruption) were quantified by multiplex immunoassay. Co-primary endpoints were defined as levels of IP-10 and IL-1α, cytokines previously associated with increased HIV susceptibility.

Results

Here we show that cervicovaginal levels of vaginal IP-10, sE-cad and several other cytokines increase rapidly after sex, regardless of condom use. The proportion of endocervical HIV target cells, including Th17 cells, activated T cells, and activated or mature dendritic cells (DCs) also increase, particularly after condomless sex. Although most of these immune changes resolve within 72 h, increases in activated cervical CD4 + T cells and Tcm persist beyond this time.

Conclusions

Penile-vaginal sex induces multiple genital immune changes that may enhance HIV susceptibility during the 72 h post-sex window that is critical for virus acquisition. This has important implications for the mucosal immunopathogenesis of HIV transmission.

Women who acquire HIV most commonly do so during penile-vaginal sex. Although the risk of HIV acquisition is higher when there is pre-existing inflammation in the female genital tract, the impact of receptive penile-vaginal sex itself on immune markers of HIV susceptibility in the genital tract has not been widely studied. We recruited heterosexual couples, without HIV or sexually-transmitted infections, and studied the impact of a single episode of penile-vaginal sex on immune cells and proteins in the female genital tract. We found that some markers within the cervix and vagina increased immediately after sex, then returned to normal. We noticed differences in these changes depending on whether the sex was condom-protected and whether the male partner was circumcised. Our findings might help us to understand how sex impacts the immune system and how this might contribute to HIV acquisition.

Mohammadi et al. evaluate immune markers and cell types associated with HIV susceptibility in the female genital tract before and after penile-vaginal sex. The authors report that these immune parameters increase rapidly and transiently after sex, with condom use affecting some of the changes observed.

Insertive condom-protected and condomless vaginal sex both have a profound impact on the penile immune correlates of HIV susceptibility

The penis is the primary site of HIV acquisition in heterosexual men. Elevated penile inflammatory cytokines increase sexual acquisition risk, and topically applied cytokines enhance foreskin HIV susceptibility in an explant model. However, the impact of penile-vaginal sex on these immune parameters is undefined. Heterosexual couples were recruited to the Sex, Couples and Science (SECS) Study, with the collection of penile swabs, semen, cervico-vaginal secretions, and blood after a period of abstinence, and repeated sampling up to 72 hours after either condomless (n = 30) or condom-protected (n = 8) penile-vaginal sex. Soluble immune parameters were quantified by multiplex immunoassay. Co-primary immune endpoints were penile levels of IL-8 and MIG, cytokines previously linked to penile HIV acquisition. One hour after sex there were dramatic increases in penile IL-8 and MIG levels, regardless of condom use, with a gradual return to baseline by 72 hours; similar patterns were observed for other chemoattractant chemokines. Penile cytokine changes were similar in circumcised and uncircumcised men, and repeated measures ANOVA and ANCOVA models demonstrated that the degree of change after condomless sex was explained by cytokine levels in their partners’ cervico-vaginal secretions. This may have important implications for the biology of penile HIV acquisition.

In heterosexual men, the penis is the primary site of Human Immunodeficiency Virus (HIV) acquisition. Levels of inflammatory cytokines in the coronal sulcus are associated with an increased HIV risk, and we hypothesized that these may be altered after insertive penile sex. Therefore, we designed the Sex, Couples and Science Study (SECS study) to define the impact of penile-vaginal sex on the penile immune correlates of HIV susceptibility. We found that multiple coronal sulcus cytokines increased dramatically and rapidly after sex, regardless of condom use, with a return to baseline levels by 72 hours. The changes observed after condomless sex were strongly predicted by cytokine concentrations in the vaginal secretions of the female partner, and were similar in circumcised and uncircumcised men. We believe that these findings have important implications for understanding the immunopathogenesis of penile HIV acquisition; in addition, they have important implications for the design of clinical studies of penile HIV acquisition and prevention.

The use of PSA as a biomarker of recent semen exposure in female reproductive health studies

Semen contains potent soluble proteins, bacteria, viruses, activated immune cells as well as anti- and pro-inflammatory cytokines that may influence the inflammatory response and alter microbial composition of the female genital tract. The presence of semen in the female genital mucosa may be a significant confounder that most studies have failed to control for in their analysis. Prostate-specific antigen (PSA), a protein secreted by the prostate into the urethra during ejaculation, is a well-established biomarker of semen exposure. Several studies have demonstrated discordance between self-reports of sexual behavior and the presence of PSA. Recent semen exposure has been shown to promote pro-inflammatory responses, stimulate the recruitment of activated immune cells and decrease Lactobacilli abundance in the female genital mucosa. As a result, it is important to understand the concordance between self-reported consistent condom use and the presence of semen biomarkers. Furthermore, to ensure that the interpretation of data in clinical studies of the immunological and microbial environment in the female genital mucosa are accurate, it is essential to establish whether semen is present in the vaginal fluid. This review explores the impact of semen exposure on the mucosal microenvironment and assesses the use of the PSA as an objective biomarker of semen exposure to reduce reliance on self-reported sexual intercourse.

Protective efficacy of the anti-HIV broadly neutralizing antibody PGT121 in the context of semen exposure

BACKGROUND

HIV-1 infections occur following viral exposure at anogenital mucosal surfaces in the presence of semen. Semen contains immunosuppressive and pro-inflammatory factors. Semen from HIV-1-infected donors contains anti-HIV-1 antibodies. We assessed if passively infused anti-HIV-1 neutralizing antibody conferred protection from rectal SHIV_SF162P3 challenge at semen exposed mucosae.

METHODS

We pooled seminal plasma from HIV-1-infected donors. The pool was screened by ELISA for antibodies against HIV-1_SF162 gp140. The ability of seminal plasma to inhibit macaque NK cells from responding to direct and antibody-dependent stimulation was assessed. The ability of seminal plasma to inhibit macaque granulocytes from mediating oxidative burst was also assessed. To demonstrate viral infectivity in the presence of seminal plasma, macaques (n = 4) were rectally challenged with SHIV_SF162P3 following exposure to 2.5 mL of seminal plasma. To evaluate if anti-HIV-1 neutralizing antibody confers protection against rectal SHIV challenge at semen exposed mucosae, eight macaques were intravenously infused with PGT121, either wild type (n = 4) or the Fc receptor binding deficient LALA variant (n = 4), and rectally challenged with SHIV_SF162P3 following exposure to 2.5 mL of seminal plasma.

FINDINGS

Anti-HIV-1_SF162 gp140 antibodies were detected in seminal plasma. Seminal plasma inhibited direct and antibody-dependent NK cell activation and granulocyte oxidative burst in vitro. Rectal SHIV_SF162P3 challenge of control macaques following seminal plasma exposure resulted in infection of all animals. All macaques infused with wild type or LALA PGT121 and challenged with SHIV_SF162P3 following seminal plasma exposure were protected.

INTERPRETATION

PGT121 conferred protection against rectal SHIV_SF162P3 challenge at semen exposed mucosae. Future research should investigate if semen alters protection conferred by antibodies more dependent on non-neutralizing functions.

FUNDING

This work was supported by a grant from the Australian National Health and Medical Research Council (APP1124680).

Leukocytospermia induces intraepithelial recruitment of dendritic cells and increases SIV replication in colorectal tissue explants

Mucosal exposure to infected semen accounts for the majority of HIV-1 transmission events, with rectal intercourse being the route with the highest estimated risk of transmission. Yet, the impact of semen inflammation on colorectal HIV-1 transmission has never been addressed. Here we use cynomolgus macaques colorectal tissue explants to explore the effect of leukocytospermia, indicative of male genital tract inflammation, on SIVmac251 infection. We show that leukocytospermic seminal plasma (LSP) has significantly higher concentration of a number of pro-inflammatory molecules compared to normal seminal plasma (NSP). In virus-exposed explants, LSP enhance SIV infection more efficiently than NSP, being the increased viral replication linked to the level of inflammatory and immunomodulatory cytokines. Moreover, LSP induce leukocyte accumulation on the apical side of the colorectal lamina propria and the recruitment of a higher number of intraepithelial dendritic cells than with NSP. These results suggest that the outcome of mucosal HIV-1 infection is influenced by the inflammatory state of the semen donor, and provide further insights into mucosal SIV/HIV-1 pathogenesis.

Recent sexual violence exposure is associated with immune biomarkers of HIV susceptibility in women

PROBLEM

HIV/AIDS and sexual violence act synergistically and compromise women's health. Yet, immuno-biological mechanisms linking sexual violence and increased HIV susceptibility are poorly understood.

METHODS

We conducted a cross-sectional pilot study of HIV-uninfected women, comparing 13 women exposed to forced vaginal penetration within the past 12 weeks (Exposed) with 25 Non-Exposed women. ELISA assays were conducted for 49 biomarkers associated with HIV pathogenesis in plasma and cervicovaginal lavage (CVL). Differences between Exposed and Non-Exposed were analyzed by linear and logistic regression, using propensity score weighting to control for age, race, socioeconomic status, menstrual cycle, and contraceptive use.

RESULTS

In CVL, Exposed women had significantly reduced chemokines MIP-3α (p < .01), MCP-1 (p < .01), and anti-HIV/wound-healing thrombospondin-1 (p = .03). They also had significantly increased inflammatory cytokine IL-1α (p < 0.01) and were more likely to have detectable wound-healing PDGF (p = .02). In plasma, Exposed women had reduced chemokines MIP-3α (p < .01) and IL-8 (p < .01), anti-inflammatory cytokine TGF-β (p = .02), anti-HIV/antimicrobial HBD-2 (p = .02), and wound-healing MMP-1 (p = 0.02). They also had increased thrombospondin-1 (p < .01) and Cathepsin B (p = .01). After applying the stringent method of false discovery rate adjustment, differences for IL-1α (p = .05) and MCP-1 (p = .03) in CVL and MIP-3α (p = .03) in plasma remained significant.

CONCLUSIONS

We report systemic and mucosal immune dysregulation in women exposed to sexual violence. As these biomarkers have been associated with HIV pathogenesis, dysregulation may increase HIV susceptibility.

Cytokine Network and Sexual Human Immunodeficiency Virus Transmission in Men Who Have Sex With Men

BACKGROUND

Seminal human immunodeficiency virus (HIV) transmission from men to their partners remains the main driver of HIV epidemics worldwide. Semen is not merely a carrier of the virus, but also provides an immunological milieu that affects HIV transmission.

METHODS

We collected blood and semen from people with HIV whose epidemiologically linked sexual partners either did or did not acquire HIV. Viral transmission was confirmed by phylogenetic linkage (HIV pol). We measured the concentration of 34 cytokines/chemokines by Luminex in the blood and semen of 21 source partners who transmitted HIV (transmitters) and 22 who did not transmit HIV (nontransmitters) to their sexual partners. Differences between cytokine profiles in transmitters versus nontransmitters were analyzed using the multivariate statistical technique of partial least square discriminant analysis.

RESULTS

The cytokine profile in seminal fluid, but not in peripheral blood, was significantly different between men who have sex with men (MSM) who transmitted HIV and those who did not transmit HIV to their sexual partners (E = 19.77; P < .01). This difference persisted after excluding people with undetectable HIV RNA levels in nontransmitters.

CONCLUSIONS

Seminal cytokine profiles correlated with transmission or nontransmission of HIV from the infected MSM to their partners, independently from seminal viral load. Seminal cytokine spectra might be a contributing determinant of sexual HIV transmission, thus providing new directions for the development of strategies aimed at preventing HIV transmission.

Concomitant Imbalances of Systemic and Mucosal Immunity Increase HIV Acquisition Risk

BACKGROUND

We previously reported association of increased cervical RANTES and decreased secretory leukocyte protease inhibitor (SLPI) with higher risk of HIV acquisition in reproductive-age women. We now examine the interaction of concomitantly altered systemic and cervical immunity on such risk.

METHODS

We measured immune biomarkers in 4390 cervical and 2390 paired serum specimens at quarterly visits in 218 HIV seroconverters and 784 seronegative women. We assessed proinflammatory (IL-1β, IL-6, IL-8, MIP-3α, and RANTES), anti-inflammatory (IL-1RA and SLPI), vascular activation (vascular endothelial growth factor and Intercellular Adhesion Molecule-1) and defensin (BD2) cervical biomarkers and systemic (peripheral blood) C reactive protein (CRP), IL-6, IL-7, and sCD14 as indicators of immune dysregulation. Biomarker levels were Box-Cox transformed and odds ratios for HIV acquisition calculated based on top quartile or higher/lower than median levels for all HIV-negative visits.

RESULTS

Subsequent HIV acquisition was associated with 5 of 14 individual biomarkers: low systemic CRP [odds ratio (OR) = 1.49, 1.21-1.83] and IL-6 (OR = 1.23, 1.00-1.51), high cervical BD-2 (OR = 1.33, 1.11-1.58) and RANTES (OR = 1.20, 1.01-1.43), and low cervical IL-1RA (OR = 0.65, 0.48-0.86). Low systemic CRP concomitant with altered cervical immunity, especially high BD2, conveyed highest HIV risk (1.63, 1.29-2.05). Additional markers of increased risk emerged when low systemic CRP coincided with: low systemic IL-6 and IL-7 (OR = 1.53, 1.18-1.97); high cervical IL-8 and MIP-3α (OR = 1.40, 1.07-1.83); high cervical IL-1β and IL-6 (OR = 1.43, 1.09-1.86); or low cervical SLPI (OR = 1.36, 1.08-1.71).

CONCLUSIONS

Changes in both peripheral and mucosal immunity may precede and predispose women to HIV infection. Suppressed systemic immunity (ie, low CRP) alone or in combination with imbalanced cervical innate immunity (high proinflammatory and low anti-inflammatory mediators) indicated increased vulnerability to infection. Understanding these combined effects on HIV susceptibility is essential to preventing new infections.

Seminal plasma contains TGF-β and CXCL10 but sperm washing before cryopreservation is beneficial for post-thawing sperm motility in Black Bengal goats (Capra hircus)

PROBLEM

Artificial insemination, which requires cryopreservation of semen, is not completely optimized in goats because bucks discharge a small volume of ejaculate and seminal plasma (SP) contains specific proteins that are detrimental to spermatozoa at cryopreservation. However, it is not known the effects of sperm washing (removal of SP) before cryopreservation on the post-thawing frozen spermatozoa of Black Bengal bucks. Moreover, it is completely unknown whether SP of goats contains TGF-β and CXCL10 that have been proven essential for fertility in other mammals.

METHODS

Thirty-five ejaculates were collected from six mature Black Bengal bucks at one-week intervals and were subjected to microscopic evaluation for semen characteristics at pre- and post-freezing condition. The concentrations of TGF-β and CXCL10 in the SP using ELISA were determined. SP was harvested with centrifugation of fresh semen at 1500 g for 15 minutes twice at room temperature.

RESULTS

Semen characteristics were significantly varied between bucks. Seminal plasma of all ejaculates contained TGF-β and CXCL10 while significant variation of concentrations between bucks was observed in case of CXCL10. Cryopreservation of semen reduced total motility and progressive motility, while sperm washing before cryopreservation was beneficial to the total motility and progressive motility of post-thawing spermatozoa.

CONCLUSION

Black Bengal buck seminal plasma was affluent of TGF-β and CXCL10 and washing of spermatozoa before cryopreservation was beneficial to the post-thawing sperm motility. The results of the current investigation will be helpful for future research on the roles of SP in female reproductive tract and pregnancy in Black Bengal goats.

Viruses in the reproductive tract: On their way to the germ line?

Studies of vertebrate genomes have indicated that all species contain in their chromosomes stretches of DNA with sequence similarity to viral genomes. How such 'endogenous' viral elements (EVEs) ended up in host genomes is usually explained in general terms such as 'they entered the germ line at some point during evolution'. This seems a correct statement, but is also rather imprecise. The vast number of endogenous viral sequences suggest that common routes to the 'germ line' may exist, as relying on chance alone may not easily explain the abundance of EVEs in modern mammalian genomes. An increasing number of virus types have been detected in human semen and a growing number of studies have reported on viral infections that cause male infertility or subfertility and on viral infections that threaten in vitro fertilisation practices. Thus, it is timely to survey the pathway(s) that viruses can use to gain access to the human germ line. Embryo transfer and semen quality studies in livestock form another source of relevant information because virus infection during reproduction is clearly unwanted, as is the case for the human situation. In this review, studies on viruses in the male and female reproductive tract and in the early embryo will be discussed to propose a plausible viral route to the mammalian germ line.

The importance of semen leukocytes in HIV-1 transmission and the development of prevention strategies

HIV-1 sexual transmission occurs mostly through contaminated semen, which is a complex mixture of soluble factors with immunoregulatory functions and cells. It is well established that semen cells from HIV-1-infected men are able to produce the virus and that are harnessed to efficiently interact with mucosal barriers exposed during sexual intercourse. Several cofactors contribute to semen infectivity and may enhance the risk of HIV-1 transmission to a partner by increasing local HIV-1 replication in the male genital tract, thereby increasing the number of HIV-1-infected cells and the local HIV-1 shedding in semen. The introduction of combination antiretroviral therapy has improved the life expectancy of HIV-1 infected individuals; however, there is evidence that systemic viral suppression does not always reflect full viral suppression in the seminal compartment. This review focus on the role semen leukocytes play in HIV-1 transmission and discusses implications of the increased resistance of cell-mediated transmission to immune-based prevention strategies.

Effect of Hormonal Contraception on Pharmacokinetics of Vaginal Tenofovir in Healthy Women: Increased Tenofovir Diphosphate in Injectable Depot Medroxyprogesterone Acetate Users

OBJECTIVE

Endogenous and exogenous contraceptive hormones may affect mucosal pharmacokinetics (PKs) of topical antiretrovirals such as tenofovir. We present PK data from healthy women using tenofovir vaginal gel, at baseline (follicular and luteal phases) and after oral contraceptive pill (OCP) or depot medroxyprogesterone acetate (DMPA) use.

METHODS

CONRAD A10-114 was a prospective, interventional, open-label, parallel study. We enrolled 74 women and 60 completed the study (32 and 28 who selected OCPs or DMPA, respectively). Participants used 2 doses of tenofovir gel separated by 2 hours, without intercourse, and were examined 3 or 11 hours after the last dose. We assessed pharmacokinetics in plasma, cervicovaginal (CV) aspirate, and vaginal tissue.

RESULTS

In general, there were no significant differences in mucosal tenofovir and tenofovir diphosphate concentrations (P > 0.23) in the follicular and luteal phases, except for lower mean tenofovir tissue concentrations (P < 0.01) in the follicular phase. Tenofovir concentrations significantly decreased in CV aspirate (P < 0.01) after contraceptive use, but overall remained very high (>10 ng/mL). Mean tissue tenofovir diphosphate increased to 6229 fmol/mg after DMPA use compared with 3693 and 1460 fmol/mg in the follicular and luteal phases, respectively (P < 0.01). The molecular conversion of tenofovir into tenofovir diphosphate was more effective in DMPA users (molecular ratio of 2.02 versus 0.65 luteal phase, P < 0.01).

CONCLUSIONS

Both menstrual cycle phase and exogenous hormones affect topical tenofovir mucosal and systemic PKs. However, high levels of tenofovir and tenofovir diphosphate were observed in the CV mucosa in the presence or absence of OCPs and DMPA, with tissue levels exceeding benchmarks of predicted mucosal anti-HIV efficacy (tenofovir >1.00 ng/mL in CV aspirate and tenofovir diphosphate >1000 fmol/mg).

A phase I randomized safety study of a single-size silicone rubber diaphragm used with or without a lactic-acid-containing diaphragm gel

OBJECTIVES

To evaluate a lactic-acid-containing diaphragm gel (Contragel®) approved outside the United States for use with a silicone rubber diaphragm (Caya®). The study gel is being evaluated as a safer alternative to nonoxynol-9 (N-9) gel, which has been associated with risk of increasing susceptibility to human immunodeficiency virus (HIV).

STUDY DESIGN

This was a Phase I randomized, parallel study evaluating the safety of the novel diaphragm gel versus hydroxyethylcellulose (HEC) universal placebo gel delivered by the study diaphragm for two 7-day test cycles of daily use, without and with intercourse. The primary clinical safety endpoint was treatment emergent adverse events. Mucosal safety endpoints included colposcopic findings, anti-Escherichia coli activity of endocervical and vaginal fluid, immune mediators, Nugent score and ectocervical immune cell density. Endpoints were assessed prior to each test cycle and at day 7 of each test cycle. We compared the two independent groups and also evaluated paired changes from baseline in each gel cohort.

RESULTS

Twenty-three participants used the study diaphragm with the novel gel (n=11) or with HEC (n=12). Use of either gel resulted in few genital AEs and no colposcopic findings. There were no differences in ectocervical histology and lymphocyte density or phenotype between the two cohorts at baseline or after each test cycle. We found no clinically important differences in the anti-microbial (anti Escherichia coli) activity of endocervical or vaginal fluid or concentrations of genital immune mediators (e.g. anti-inflammatory secretory leukocyte protease inhibitor (SLPI) or pro-inflammatory mediator RANTES) between the two gel cohorts at any visit. There were no important paired changes from baseline among participants using either gel in Nugent score, ectocervical histology or anti-microbial activity of genital secretions.

CONCLUSIONS

We found no clinically significant differences in clinical and mucosal safety endpoints between the two cohorts. The mucosal safety profiles of the study gel and HEC placebo gel were similar.

IMPLICATIONS

Our data demonstrate no clinically important differences between the safety profiles of the lactic-acid-containing diaphragm gel versus HEC placebo gel when used with the study diaphragm. N-9 can no longer be used with contraceptive diaphragms in high HIV prevalence regions. Although larger studies are needed, the novel gel appears safe for use with the study diaphragm, which is the first over-the-counter, non-hormonal, diaphragm.

The Potential Role of Seminal Plasma in the Fertilization Outcomes

For human infertility both male and female factors may be equally important. Searching for molecular biomarkers of male infertility, neglected for decades, and the attempts to explain regulatory mechanisms of fertilization become thus extremely important. Apart from examination of the structure and function of male gametes, also the possible importance of seminal plasma components should be considered. In this article we discuss data that indicate for the substantial significance of active seminal plasma components for conception and achievement of healthy pregnancy. Seminal plasma impact on the storage and cryopreservation of human and animal sperm and regulatory role of glycodelin on human sperm capacitation as well as hypothesized course of female immune response to allogenic sperm and conceptus has been discussed. The possible involvement of carbohydrates in molecular mechanism of fetoembryonic defense has been also mentioned.

Inhibition of influenza virus activity by the bovine seminal plasma protein PDC-109

A number of viruses causing sexually transmissible diseases are transmitted via mammalian seminal plasma. Several components of seminal plasma have been shown to influence those viruses and their physiological impact. To unravel whether components of seminal plasma could affect viruses transmitted via other pathways, it was investigated here whether the bovine seminal plasma protein PDC-109, belonging to the Fn-type 2 protein family, influences the activity of influenza A viruses, used as a model for enveloped viruses. We found that PDC-109 inhibits the fusion of influenza virus with human erythrocyte membranes and leads to a decreased viral infection in MDCK cells. In the presence of the head group of the phospholipid phosphatidylcholine, phosphorylcholine, the inhibitory effect of PDC-109 was attenuated. This indicates that the impact of the protein is mainly caused by its binding to viral and to erythrocyte membranes thereby interfering with virus-cell binding. Our study underlines that Fn-type 2 proteins have to be considered as new antiviral components present in mammalian seminal plasma.

Short Communication: Effect of Seminal Plasma on Functions of Monocytes and Granulocytes

Most HIV-1 transmissions occur at mucosae and involve exposure to semen. Semen contains immunomodulatory factors, which inhibit anti-HIV-1 natural killer cell and T cell responses. We demonstrate high concentrations (1:2 dilution) of seminal plasma (SP) inhibit monocyte phagocytosis and anti-HIV-1 Fc-dependent functions of both neutrophils and monocytes. In addition, slightly lower SP concentrations (1:2-1:10 dilutions) inhibit granulocyte phagocytosis and oxidative burst of both monocytes and granulocytes. These observations may have implications for HIV-1 infectivity after mucosal exposure.

Seminal exosomes and HIV-1 transmission

Exosomes are endosomal‐derived membrane‐confined nanovesicles secreted by many (if not all) cell types and isolated from every human bodily fluid examined up to now including plasma, semen, vaginal secretions and breast milk. Exosomes are thought to represent a new player in cell‐to‐cell communication pathways and immune regulation, and be involved in many physiological and pathological processes. Susceptibility to HIV‐1 infection can be impacted by exosomes, while HIV‐1 pathogenesis can alter exosomal function and composition. Exosomes isolated from semen and vaginal fluid of healthy individuals can inhibit HIV‐1 infection and/or potently block viral transfer in vitro. However, the role of exosomes in HIV‐1 transmission and progression is not fully understood yet and some studies show conflicting results, mainly for exosomes isolated from plasma and breast milk. Determining the composition of exosomes from infected donors and studying their interaction with HIV‐1 in vitro compared to exosomes isolated from uninfected donors will provide insights into the role exosomes play in HIV‐1 transmission during sexual intercourse and breastfeeding.

Modulation of the CCR5 Receptor/Ligand Axis by Seminal Plasma and the Utility of In Vitro versus In Vivo Models

Sexual HIV-1 transmission occurs primarily in the presence of semen. Although data from macaque studies suggest that CCR5⁺ CD4⁺ T cells are initial targets for HIV-1 infection, the impact of semen on T cell CCR5 expression and ligand production remains inconclusive. To determine if semen modulates the lymphocyte CCR5 receptor/ligand axis, primary human T cell CCR5 expression and natural killer (NK) cell anti-HIV-1 antibody-dependent beta chemokine production was assessed following seminal plasma (SP) exposure. Purified T cells produce sufficient quantities of RANTES to result in a significant decline in CCR5^bright T cell frequency following 16 h of SP exposure (P = 0.03). Meanwhile, NK cells retain the capacity to produce limited amounts of MIP-1α/MIP-1β in response to anti-HIV-1 antibody-dependent stimulation (median, 9.5% MIP-1α⁺ and/or MIP-1β⁺), despite the immunosuppressive nature of SP. Although these in vitro experiments suggest that SP-induced CCR5 ligand production results in the loss of surface CCR5 expression on CD4⁺ T cells, the in vivo implications are unclear. We therefore vaginally exposed five pigtail macaques to SP and found that such exposure resulted in an increase in CCR5⁺ HIV-1 target cells in three of the animals. The in vivo data support a growing body of evidence suggesting that semen exposure recruits target cells to the vagina that are highly susceptible to HIV-1 infection, which has important implications for HIV-1 transmission and vaccine design.IMPORTANCE The majority of HIV-1 vaccine studies do not take into consideration the impact that semen exposure might have on the mucosal immune system. In this study, we demonstrate that seminal plasma (SP) exposure can alter CCR5 expression on T cells. Importantly, in vitro studies of T cells in culture cannot replicate the conditions under which immune cells might be recruited to the genital mucosa in vivo, leading to potentially erroneous conclusions about the impact of semen on mucosal HIV-1 susceptibility.

Exogenous oestrogen inhibits genital transmission of cell-associated HIV-1 in DMPA-treated humanized mice

Introduction

HIV affects more women than any other life‐threatening infectious agent, and most infections are sexually transmitted. HIV must breach the female genital tract mucosal barrier to establish systemic infection, and clinical studies indicate virus more easily evades this barrier in women using depot‐medroxyprogesterone acetate (DMPA) and other injectable progestins for contraception. Identifying a potential mechanism for this association, we learned DMPA promotes susceptibility of wild‐type mice to genital herpes simplex virus type 2 (HSV‐2) infection by reducing genital tissue expression of the cell‐cell adhesion molecule desmoglein‐1 (DSG‐1) and increasing genital mucosal permeability. Conversely, DMPA‐mediated increases in genital mucosal permeability and HSV‐2 susceptibility were eliminated in mice concomitantly administered exogenous oestrogen (E). To confirm and extend these findings, herein we used humanized mice to define effects of systemic DMPA and intravaginal (ivag) E administration on susceptibility to genital infection with cell‐associated HIV‐1.

Methods

Effects of DMPA or an intravaginal (ivag) E cream on engraftment of NOD‐scid‐IL‐2Rgc^null (NSG) mice with human peripheral blood mononuclear cells (hPBMCs) were defined with flow cytometry. Confocal microscopy was used to evaluate effects of DMPA, DMPA and E cream, or DMPA and the pharmacologically active component of the cream on vaginal tissue DSG‐1 expression and genital mucosal permeability to low molecular weight (LMW) molecules and hPBMCs. In other studies, hPBMC‐engrafted NSG mice (hPBMC‐NSG) received DMPA or DMPA and ivag E cream before genital inoculation with 10⁶ HIV‐1‐infected hPBMCs. Mice were euthanized 10 days after infection, and plasma HIV‐1 load quantified by qRT‐PCR and splenocytes used to detect HIV‐1 p24 antigen via immunohistochemistry and infectious virus via TZM‐bl luciferase assay.

Results

Whereas hPBMC engraftment was unaffected by DMPA or E treatment, mice administered DMPA and E (cream or the pharmacologically active cream component) displayed greater vaginal tissue expression of DSG‐1 protein and decreased vaginal mucosal permeability to LMW molecules and hPBMCs versus DMPA‐treated mice. DMPA‐treated hPBMC‐NSG mice were also uniformly susceptible to genital transmission of cell‐associated HIV‐1, while no animal concomitantly administered DMPA and E cream acquired systemic HIV‐1 infection.

Conclusion

Exogenous E administration reduces susceptibility of DMPA‐treated humanized mice to genital HIV‐1 infection.

Seminal Plasma Exposures Strengthen Vaccine Responses in the Female Reproductive Tract Mucosae

HIV-1 sexual transmission occurs mainly via mucosal semen exposures. In the female reproductive tract (FRT), seminal plasma (SP) induces physiological modifications, including inflammation. An effective HIV-1 vaccine should elicit mucosal immunity, however, modifications of vaccine responses by the local environment remain to be characterized. Using a modified vaccinia virus Ankara (MVA) as a vaccine model, we characterized the impact of HIV-1⁺ SP intravaginal exposure on the local immune responses of non-human primates. Multiple HIV-1⁺ SP exposures did not impact the anti-MVA antibody responses. However, SP exposures revealed an anti-MVA responses mediated by CD4⁺ T cells, which was not observed in the control group. Furthermore, the frequency and the quality of specific anti-MVA CD8⁺ T cell responses increased in the FRT exposed to SP. Multi-parameter approaches clearly identified the cervix as the most impacted compartment in the FRT. SP exposures induced a local cell recruitment of antigen presenting cells, especially CD11c⁺ cells, and CD8⁺ T cell recruitment in the FRT draining lymph nodes. CD11c⁺ cell recruitment was associated with upregulation of inflammation-related gene expression after SP exposures in the cervix. We thus highlight the fact that physiological conditions, such as SP exposures, should be taken into consideration to test and to improve vaccine efficacy against HIV-1 and other sexually transmitted infections.

Mucosa: Key Interactions Determining Sexual Transmission of the HIV Infection

In the context of HIV sexual transmission at the genital mucosa, initial interactions between the virus and the mucosal immunity determine the outcome of the exposure. Hence, these interactions have been deeply explored in attempts to undercover potential targets for developing preventative strategies. The knowledge gained has led to propose a hypothetical model for mucosal HIV transmission. Subsequent research studies on this topic further revealed new mechanisms and identified new host-HIV interactions. This review aims at integrating these findings to inform better and update the current model of HIV transmission. At the earliest stage of virus exposure, the epithelial integrity and the presence of antiviral factors are critical in preventing viral entry to the submucosa. However, the virus has been shown to enter to the submucosa in the presence of physical abrasion or via epithelial transmigration using paracellular passage or transcytosis mechanisms. The efficiency of these processes is greater with cell-associated viral inoculums and can be influenced by the presence of viral and immune factors, and by the structure of the exposed epithelium. Once the virus reaches the submucosa, dendritic cells and fibroblasts, as recently described, have been shown in vitro of being capable of facilitating the transfer of viral particles to susceptible cells, leading to viral dissemination, most likely in a trans-infection manner. The presence of activated CD4⁺ T cells in submucosa increases the probability of infection, where the predominant microbiota could be implicated through the modulation of an inflammatory microenvironment. Other factors such as genital fluids and hormones could also play an essential role in HIV transmission. Here, we review the most recent evidence described for mucosal HIV-transmission contributing with the understanding of this phenomenon.

Vehicles of intercellular communication: exosomes and HIV-1

The terms extracellular vesicles, microvesicles, oncosomes, or exosomes are often used interchangeably as descriptors of particles that are released from cells and comprise a lipid membrane that encapsulates nucleic acids and proteins. Although these entities are defined based on a specific size range and/or mechanism of release, the terminology is often ambiguous. Nevertheless, these vesicles are increasingly recognized as important modulators of intercellular communication. The generic characterization of extracellular vesicles could also be used as a descriptor of enveloped viruses, highlighting the fact that extracellular vesicles and enveloped viruses are similar in both composition and function. Their high degree of similarity makes differentiating between vesicles and enveloped viruses in biological specimens particularly difficult. Because viral particles and extracellular vesicles are produced simultaneously in infected cells, it is necessary to separate these populations to understand their independent functions. We summarize current understanding of the similarities and differences of extracellular vesicles, which henceforth we will refer to as exosomes, and the enveloped retrovirus, HIV-1. Here, we focus on the presence of these particles in semen, as these are of particular importance during HIV-1 sexual transmission. While there is overlap in the terminology and physical qualities between HIV-1 virions and exosomes, these two types of intercellular vehicles may differ depending on the bio-fluid source. Recent data have demonstrated that exosomes from human semen serve as regulators of HIV-1 infection that may contribute to the remarkably low risk of infection per sexual exposure.

Inflammatory Cytokine Profiles of Semen Influence Cytokine Responses of Cervicovaginal Epithelial Cells

Genital inflammatory cytokine responses increase HIV risk. Since male partner semen is a complex mixture of immune-modulatory prostaglandins and cytokines, we hypothesized that exposure to semen may influence genital inflammation in women. Here, we investigated cytokine response kinetics of cervical cells following stimulation with seminal plasma from HIV-negative and HIV-positive men characterized as having low or high concentrations of inflammatory cytokines. Irrespective of the HIV status or semen cytokine profile, in vitro stimulation of cervical cells with seminal plasma resulted in significantly elevated concentrations of secreted IL-6, IL-8, TNF-β, MCP-1, GM-CSF, and VEGF within 8 h of stimulation, which tended to decline by 24 h, although this was only significant for TNF-β. Consistent with this, cervical cells responded to seminal plasma with increases in IL-8 and IL-1β mRNA expression of 10-fold. These findings suggest that the impact of semen on local female genital cytokines is likely transient. Although these findings suggest that the impact of semen on local female genital cytokines may not be sustained long-term, this heightened genital inflammation may have implications for HIV risk in women.

A Longitudinal Assessment of Cervical Inflammation and Immunity Associated with HIV-1 Infection, Hormonal Contraception, and Pregnancy

Hormonal contraception (HC), particularly injectable depot-medroxyprogesterone acetate (DMPA), has been associated with increased HIV acquisition and higher levels of cervical regulated upon activation, normal T-cell expressed, and secreted (RANTES), also associated with HIV seroconversion. Longitudinal changes in cervical immunity associated with DMPA and combined oral contraceptives (COCs) have not been studied. Cervical samples from 216 HIV seroconverters in Uganda and Zimbabwe with matched samples from 727 HIV-uninfected controls were collected at two quarterly visits before (t - 2, t - 1), at (t0), and two visits following (t + 1, t + 2) HIV seroconversion and corresponding visits for HIV-negative controls. We measured 10 biomarkers of inflammation and immunity and used generalized linear models to estimate and compare biomarker levels across HIV status, contraceptive, and pregnancy groups. Biomarkers remained relatively stable across visits for controls, while in HIV-infected women cervical immunity started to change before seroconversion with RANTES and BD-2 increased and secretory leukocyte protease inhibitor (SLPI) decreased at t - 1 and continued to change at t0 with ICAM-1 up and IL-8 down and with more biomarkers after seroconversion (IL-1β, IL-6, MIP-3α, VEGF, and IL-1RA down and IL-1RA:IL-1β ratio up). In multivariable analyses, seroconverters had higher BD-2 at t - 1, higher RANTES and lower SLPI from t - 1 through t + 2, and lower IL-8 and IL-1RA at and/or after seroconversion compared to nonseroconverters. Compared to non-HC users, DMPA users had higher RANTES at all visits and lower BD-2 at t - 2 through t0, while COC users and pregnant women had higher IL-8 and SLPI at all visits; COC users also had lower BD-2 preseroconversion; pregnant women had lower RANTES at t0 - t + 2. Longitudinal patterns of cervical immunity differ between HIV seroconverters and HIV-negative women; seroconverters demonstrate increased RANTES and decreased SLPI starting before and continuing postseroconversion. Furthermore, these patterns are differentially regulated by DMPA, COC, and pregnancy.

Zika Virus Trafficking and Interactions in the Human Male Reproductive Tract

Sexual transmission of Zika virus (ZIKV) is a matter of great concern. Infectious viral particles can be shed in semen for as long as six months after infection and can be transferred to male and female sexual partners during unprotected sexual intercourse. The virus can be found inside spermatozoa and could be directly transferred to the oocyte during fertilization. Sexual transmission of ZIKV can contribute to the rise in number of infected individuals in endemic areas as well as in countries where the mosquito vector does not thrive. There is also the possibility, as has been demonstrated in mouse models, that the vaginal deposition of ZIKV particles present in semen could lead to congenital syndrome. In this paper, we review the current literature to understand ZIKV trafficking from the bloodstream to the human male reproductive tract and viral interactions with host cells in interstitial spaces, tubule walls, annexed glands and semen. We hope to highlight gaps to be filled by future research and potential routes for vaccine and antiviral development.

Wnt Signaling Pathway in Uterus of Normal and Seminal Vesicle Excised Mated Mice during Pre-implantation Window

Introduction

The importance of seminal vesicle secretion and uterine Wnt signaling for uterus preparation and embryo implantation has been described.

Materials and Methods

In this study, we evaluated the gene expression of Wnt ligands (Wnt4 and Wnt5a) and their corresponding receptors (Fzd2 and Fzd6) using qRT-PCR and active β-catenin protein levels using western blotting in the uterine tissue of female mice mated with intact and seminal vesicle-excised (SVX) males during the pre-implantation window. We evaluated the association between these factors and implantation rates and embryo spacing.

Results

mRNA expression of Wnt4 and Wnt5a and active β-catenin protein levels decreased from Day 1 to Day 4, but reached a peak on the fifth day of pregnancy. Fzd2 also reached its highest level on Day 5. Fzd6 expression showed a decreasing trend towards the day of implantation. Lack of seminal vesicle secretion decreased Wnt4 and Wnt5a expression on Days 1 and 5 and β-catenin levels on Day 5. There were almost no significant differences in expression levels of the Fzd2 and Fzd6 receptors between groups. There were positive and negative correlations, respectively, between implantation rates and embryo spacing and Wnt4, Wnt5a and active β-catenin in the control group, but such correlations were not observed in the SVX-mated mice.

Conclusions

Significant changes occurred in the expression of several Wnt signaling members and there was a significant association between Wnt signaling and embryo implantation. Seminal vesicle secretion affects Wnt signaling in mice and consequently also affects murine embryo implantation.

Immune biomarkers and anti-HIV activity in the reproductive tract of sexually active and sexually inactive adolescent girls

PROBLEM

Adolescent girls are disproportionately affected by the HIV/AIDS pandemic, accounting for 22% of all new HIV infections globally. Yet little is known regarding the immune microenvironment of the adolescent female reproductive tract, especially regarding differences among sexually active and inactive girls, a critical parameter to evaluate HIV susceptibility associated with young age and sexual debut.

METHODS

Cervico-vaginal lavage (CVL) was collected from sexually active (10) and inactive (8) girls aged 11-19 years and analyzed by ELISA for inflammation-associated biomarkers IL-6, IL-8, TNF-α, MIP-3α, IL-1α, IL-1β, matrix metalloproteinases (MMP) 1, 2, 7, 8, and 9, as well as anti-HIV mediators, Elafin, SLPI, human beta-defensin 2, and tissue inhibitor of matrix metalloproteinases (TIMP) 1 and 2. Cervical ectopy was analyzed using Volocity. Anti-HIV activity was determined by TZM-bl assay. Statistical analyses were performed using GraphPad Prism and R.

RESULTS

Sexually inactive girls had significantly higher levels of TNF-α (P = .029) in CVL compared to sexually active girls. In contrast, sexually active girls showed a trend toward higher levels of IL-1α (P = .051) compared to the sexually inactive girls. Heat-map correlations between cervical ectopy and immune biomarkers were also distinct between the 2 populations with significant positive associations between % ectopy and inflammation-associated biomarkers IL-6, IL-1β, IL-8, MIP-3α, MMP-8, and MMP-9 observed in the sexually inactive but not sexually active group.

CONCLUSION

Higher pro-inflammatory biomarker TNF-α, as well as a distinct inflammation-associated immune clustering in sexually inactive girls, can potentially increase risk for infections including HIV upon sexual debut. Future studies with larger sample sizes are needed to characterize the immune parameters associated with sexual activity.

Seminal vesicle fluid increases the efficacy of intravaginal HSV-2 vaccination

Once considered merely as a vehicle for spermatozoa, it is now clear that seminal plasma (SP) induces a variety of biological actions on the female reproductive tissues able to modulate the immune response against paternal antigens. To our knowledge, the influence of SP on the immune response against sexually transmitted pathogens has not been yet evaluated. We here analyzed whether the seminal vesicle fluid (SVF), which contributes almost 60% of the SP volume in mice, could modulate the immune response against herpes simplex virus type 2 (HSV-2). We found that SVF does not modify the course of primary infection, but markedly improved protection conferred by vaginal vaccination with inactivated HSV-2 against a lethal challenge. This protective effect was shown to be associated to a robust memory immune response mediated by CD4+ and CD8+ T cells in both the lymph nodes draining the vagina and the vaginal mucosa, the site of viral replication. In contrast with the widespread notion that SP acts as an immunosuppressive agent, our results suggest that SVF might improve the female immune response against sexually transmitted pathogens.

In vitro models for deciphering the mechanisms underlying the sexual transmission of viruses at the mucosal level

Sexually transmitted viruses infect the genital and colorectal mucosa of the partner exposed to contaminated genital secretions through a wide range of mechanisms, dictated in part by the organization of the mucosa. Because understanding the modes of entry into the organism of viruses transmitted through sexual intercourse is a necessary prerequisite to the design of treatments to block those infections, in vitro modeling of the transmission is essential. The aim of this review is to present the models and methodologies available for the in vitro study of the interactions between viruses and mucosal tissue and for the preclinical evaluation of antiviral compounds, and to point out their advantages and limitations according to the question being studied.

Epigallocatechin Gallate Inhibits Macaque SEVI-Mediated Enhancement of SIV or SHIV Infection

BACKGROUND

Human semen contains a factor that can enhance HIV infection up to 10-fold in cultures. This factor is termed semen-derived enhancer of virus infection (SEVI) and is composed of proteolytic fragments (PAP248-286) from prostatic acid phosphatase in semen. In this study, we examined whether macaque SEVI can facilitate simian immunodeficiency virus (SIV) or chimeric simian/human immunodeficiency virus (SHIV) infection. We also studied the effect of epigallocatechin gallate (EGCG) on macaque SEVI-mediated SIV or SHIV enhancement.

METHODS

SIV or SHIV was mixed with different concentrations of macaque SEVI in the presence or absence of EGCG. The mixture was added to cultures of TZM-bl cells or macaque PBMCs. The effect of EGCG on macaque SEVI was measured by Congo-red staining assay and thioflavin T (ThT) fluorescence assay and was visualized by a transmission electron microscope.

RESULTS

We identified that there is one amino acid difference at the site of 277 between human PAP248-286 and macaque PAP248-286. Macaque SEVI significantly enhanced SIV or SHIV infection of TZM-bl cells and macaque PBMCs. EGCG could block macaque SEVI-mediated enhancement of SIV or SHIV infection. Mechanistically, EGCG could degrade the formation of macaque SEVI amyloid fibrils that facilitates HIV attachment to the target cells.

CONCLUSIONS

The finding that macaque SEVI could enhance SIV or SHIV infection indicates the possibility to use the macaque SEVI in vivo studies with the macaque models. In addition, future studies are necessary to examine whether EGCG can be used as an effective microbicide for preventing SIV or SHIV mucosal transmission.

Seminal plasma induces inflammation and enhances HIV-1 replication in human cervical tissue explants

The most immediate and evident effect of mucosal exposure to semen in vivo is a local release of proinflammatory mediators accompanied by an influx of leukocytes into the female genital mucosa (FGM). The implication of such response in HIV-1 transmission has never been addressed due to limitations of currently available experimental models. Using human tissue explants from the uterine cervix, we developed a system of mucosal exposure to seminal plasma (SP) that supports HIV-1 replication. Treatment of ectocervical explants with SP resulted in the upregulation of inflammatory and growth factors, including IL-6, TNF, CCL5, CCL20, CXCL1, and CXCL8, and IL1A, CSF2, IL7, PTGS2, as evaluated by measuring protein levels in explant conditioned medium (ECM) and gene expression in tissue. SP treatment was also associated with increased recruitment of monocytes and neutrophils, as observed upon incubation of peripheral blood leukocytes with ECM in a transwell system. To evaluate the impact of the SP-mediated response on local susceptibility to HIV-1, we infected ectocervical explants with the CCR5-tropic variant HIV-1BaL either in the presence of SP, or after explant pre-incubation with SP. In both experimental settings SP enhanced virus replication as evaluated by HIV-1 p24gag released in explant culture medium over time, as well as by HIV-1 DNA quantification in explants infected in the presence of SP. These results suggest that a sustained inflammatory response elicited by SP soon after coitus may promote HIV-1 transmission to the FGM. Nevertheless, ectocervical tissue explants did not support the replication of transmitted/founder HIV-1 molecular clones, regardless of SP treatment. Our system offers experimental and analytical advantages over traditional models of HIV-1 transmission for the study of SP immunoregulatory effect on the FGM, and may provide a useful platform to ultimately identify new determinants of HIV-1 infection at this site.

High Levels of Chemokine C-C Motif Ligand 20 in Human Milk and Its Production by Oral Keratinocytes

BACKGROUND

Chemokine C-C motif ligand 20 (CCL20) is implicated in the formation and function of mucosal lymphoid tissues. Although CCL20 is secreted by many normal human tissues, no studies have evaluated the presence of CCL20 in human milk or its production by oral keratinocytes stimulated by human milk.

OBJECTIVE

To evaluate the presence of CCL20 in breast milk and verify CCL20 secretion in vitro by oral keratinocytes stimulated with human and bovine milk, as well as its possible association with breast milk lactoferrin levels.

MATERIALS AND METHODS

The levels of CCL20 and lactoferrin were measured by enzyme-linked immunosorbent assay in human milk at three different stages of maturation from 74 healthy breastfeeding mothers. In vitro, oral keratinocytes were stimulated with human and bovine milk, and CCL20 was measured in their supernatant.

RESULTS

High concentrations of CCL20 were detected in the human breast milk samples obtained during the first week (1,777.07 pg/mL) and second week postpartum (1,523.44 pg/mL), with a significantly low concentration in samples at 3-6 weeks postpartum (238.42 pg/mL; p < 0.0001). Human breast milk at different weeks postpartum stimulated higher CCL20 secretion by oral keratinocytes compared with bovine milk (p < 0.05). Such stimulation had no association with breast milk lactoferrin concentration.

CONCLUSION

CCl20 is present at high levels in human milk, predominantly in the first and second week postpartum, but at significantly lower levels at 3-6 weeks postpartum. Human milk is capable of stimulating CCL20 secretion by oral keratinocytes, and this induction had no association with breast milk lactoferrin concentration.

Modulation of innate and adaptive cellular immunity relevant to HIV-1 vaccine design by seminal plasma

OBJECTIVES

Mucosal exposure to HIV-1 infection generally occurs in the presence of semen. Immunomodulation by seminal plasma is well described in the reproductive biology literature. Little is known, however, about the impact of seminal plasma on innate and adaptive anti-HIV-1 cellular immunity.

DESIGN

The study investigated the effects of seminal plasma on immune responses considered important for prophylactic HIV-1 vaccine development, namely innate and adaptive cellular immunity mediated by natural killer (NK) cells and T cells, respectively.

METHODS

The ability of seminal plasma to modulate direct, antibody-dependent and cytokine-stimulated NK cell activation was assessed utilizing intracellular cytokine staining. Direct and antibody-dependent cellular cytotoxicity was assessed using lactate dehydrogenase release assays. The effects of seminal plasma on T-cell activation upon stimulation with staphylococcus enterotoxin B or HIV-1 Gag peptides were assessed by intracellular cytokine staining. The impact of seminal plasma on redirected cytolysis mediated by T cells was measured using lactate dehydrogenase release assays.

RESULTS

Both direct and antibody-dependent NK cell activation were dramatically impaired by the presence of either HIV-1-uninfected or HIV-1-infected seminal plasma in a dose-dependent manner. Additionally, seminal plasma suppressed both direct and antibody-dependent NK cell-mediated cytolysis, including anti-HIV-1 antibody-dependent cytolysis of gp120-pulsed CEM.NKr-CCR5 cells. Finally, seminal plasma attenuated both HIV-1 Gag-specific and staphylococcus enterotoxin B-induced CTL activation.

CONCLUSIONS

Semen contains potent immunosuppressors of both NK cell and CD8 T-cell-mediated anti-HIV-1 immune responses. This could impede attempts to provide vaccine-induced immunity to HIV-1.

Nanomedicine in the development of anti-HIV microbicides

Prevention plays an invaluable role in the fight against HIV/AIDS. The use of microbicides is considered an interesting potential approach for topical pre-exposure prophylaxis of HIV sexual transmission. The prospects of having an effective product available are expected to be fulfilled in the near future as driven by recent and forthcoming results of clinical trials. Different dosage forms and delivery strategies have been proposed and tested for multiple microbicide drug candidates presently at different stages of the development pipeline. One particularly interesting approach comprises the application of nanomedicine principles to the development of novel anti-HIV microbicides, but its implications to efficacy and safety are not yet fully understood. Nanotechnology-based systems, either presenting inherent anti-HIV activity or acting as drug nanocarriers, may significantly influence features such as drug solubility, stability of active payloads, drug release, interactions between active moieties and virus/cells, intracellular drug delivery, drug targeting, safety, antiviral activity, mucoadhesive behavior, drug distribution and tissue penetration, and pharmacokinetics. The present manuscript provides a comprehensive and holistic overview of these topics as relevant to the development of vaginal and rectal microbicides. In particular, recent advances pertaining inherently active microbicide nanosystems and microbicide drug nanocarriers are discussed.

Biomarkers of Cervical Inflammation and Immunity Associated with Cervical Shedding of HIV-1

BACKGROUND

Cervicovaginal HIV shedding is associated with increased female-to-male and mother-to-child transmission. Genital inflammation may increase shedding through cytokines/chemokines which recruit and activate HIV target cells. We evaluated whether cervical immune mediators present before seroconversion affected HIV shedding and whether mediators differed between shedders and nonshedders.

METHODS

We used cervical samples from 187 African women with documented HIV seroconversion in the Hormonal Contraception and HIV study. Samples were from the two visits before seroconversion (T-2 and/or T-1), and/or at seroconversion (T0), and/or the two visits (T + 1 and/or T + 2) after seroconversion. We measured interleukin (IL)-1β, IL-1 Receptor Antagonist (IL-1RA), IL-6, IL-8, RANTES (Regulated on Activation, Normal T-Cell Expressed and Secreted), MIP-3α, vascular endothelial growth factor (VEGF), Intercellular Adhesion Molecule-1 (ICAM-1), secretory leukocyte protease inhibitor (SLPI), and BD-2 and used the Wilcoxon test and generalized linear models to evaluate the association between mediators and shedding.

RESULTS

The only immune mediator that differed at T-1 was RANTES, which was higher among shedders (p ≤ .05). HIV seroconversion was followed by significant decreases in many mediators, but a significant increase in RANTES. The magnitude of the change was significantly different for shedders versus nonshedders with regard to RANTES (increased in both groups, significantly more so in shedders), SLPI (decreased in both groups, significantly more so in shedders), and MIP-3α (decreased in shedders and increased in nonshedders). At T0, shedders had lower levels of SLPI and MIP-3α than nonshedders.

CONCLUSIONS

In this study, a specific immune mediator profile was associated with risk of cervical HIV shedding. Higher and increasing levels of RANTES and lower and decreasing levels of SLPI and MIP-3α were associated with increased risk of HIV shedding.

Broadly Neutralizing Anti-HIV Antibodies Prevent HIV Infection of Mucosal Tissue Ex Vivo

Broadly neutralizing monoclonal antibodies (nAbs) specific for HIV are being investigated for use in HIV prevention. Due to their ability to inhibit HIV attachment to and entry into target cells, nAbs may be suitable for use as topical HIV microbicides. As such, they would present an alternative intervention for individuals who may not benefit from using antiretroviral-based products for HIV prevention. We theorize that nAbs can inhibit viral transmission through mucosal tissue, thus reducing the incidence of HIV infection. The efficacy of the PG9, PG16, VRC01, and 4E10 antibodies was evaluated in an ex vivo human model of mucosal HIV transmission. nAbs reduced HIV transmission, causing 1.5- to 2-log10 reductions in HIV replication in ectocervical tissues and ≈3-log10 reductions in HIV replication in colonic tissues over 21 days. These antibodies demonstrated greater potency in colonic tissues, with a 50-fold higher dose being required to reduce transmission in ectocervical tissues. Importantly, nAbs retained their potency and reduced viral transmission in the presence of whole semen. No changes in tissue viability or immune activation were observed in colonic or ectocervical tissue after nAb exposure. Our data suggest that topically applied nAbs are safe and effective against HIV infection of mucosal tissue and support further development of nAbs as a topical microbicide that could be used for anal as well as vaginal protection.

Critical Review: Immunomodulation by Seminal Factors and Implications for Male-to-Female HIV-1 Transmission

The role of semen in heterosexual transmission of the HIV-1 has been marginally viewed as an inert vehicle for the delivery of virus. However, studies from the field of reproductive biology have made it clear that seminal fluid is a complex and dynamic medium containing high concentrations of factors that play key roles in modulating the local immune response in the female reproductive tract during fertilization and embryogenesis. It is therefore strongly implied that the same seminal factors responsible for guiding the immune response in reproduction also play a role in male-to-female transmission of HIV-1. To begin to understand how these factors affect male-to-female HIV-1 transmission, multiple studies have comparatively profiled the contents of seminal fluid collected from uninfected and HIV-1-infected men. This review provides an overview of these studies, as well as a discussion of the potential impact of semen on HIV-1 transmission.

Vaginal microbiota and sexually transmitted infections that may influence transmission of cell-associated HIV

Vaginal microbiota and sexually transmitted infections (STIs) are likely to influence the transmission of cell-associated human immunodeficiency virus (HIV). Lactic acid produced by Lactobacillus-dominated microbiota (Nugent score 0-3) will likely inhibit transmission, especially female-to-male transmission. In contrast, polymicrobial microbiota (Nugent score 4-10), community state types IV-A and IV-B, and STIs will likely increase transmission of cell-associated HIV.

Characteristics and quantities of HIV host cells in human genital tract secretions

Human immunodeficiency virus (HIV)-infected leukocytes have been detected in genital secretions from HIV-infected men and women and may play an important role in the sexual transmission of HIV. However, they have been largely overlooked in studies on mechanisms of HIV transmission and in the design and testing of HIV vaccine and microbicide candidates. This article describes the characteristics and quantities of leukocytes in male and female genital secretions under various conditions and also reviews evidence for the involvement of HIV-infected cells in both horizontal and vertical cell-associated HIV transmission. Additional research is needed in this area to better target HIV prevention strategies.

Role of Seminal Plasma in Human Female Reproductive Failure: Immunomodulation, Inflammation, and Infections

Human seminal plasma contains factors that can regulate the female immune system and potentially promote reproductive fitness. Adverse effects on fertility and pregnancy may occur when seminal plasma provides insufficient, excessive, or altered signals or when the female partner is incapable of receiving these signals.

Transforming growth factor beta 1 up-regulates CD169 (sialoadhesin) expression on monocyte-derived dendritic cells: role in HIV sexual transmission

OBJECTIVE

Recent data describe CD169 (also called sialoadhesin or Siglec-1) as the main HIV-1 receptor expressed by mucosal dendritic cells involved in the capture of the virus and its transmission to target cells. In this study, we investigated the effect of transforming growth factor beta 1 (TGF-β1), a cytokine found in abundance in semen, on the expression of CD169 on dendritic cells in order to characterize its potential role in the capture of HIV-1 particles by these antigen-presenting cells.

METHODS

Monocyte-derived dendritic cells (MDDCs) were cultured in the presence of lipopolysaccharide, pro-inflammatory cytokines [interleukin (IL)-1β and tumor necrosis factor alpha (TNF-α)] or different concentrations of TGF-β1, and analyzed for maturation marker and Siglec expression. The ability of MDDCs to capture HIV particles following the different treatments was also analyzed.

RESULTS

TGF-β1 treatment promotes a significant increase of CD169 expression on MDDCs. This effect was specific since neither DC-SIGN nor other Siglec expressions were changed. The CD169 increase was due to a de-novo synthesis as evidenced by Western blot experiment. This up-regulation was well correlated to the concentration of TGF-β1 and associated with an increase of the MDDC ability to bind HIV particles. Interestingly, this phenomenon was independent of the maturation status of MDDCs.

CONCLUSION

This study demonstrates that the most abundant cytokine present in semen (TGF-β1) is able to enhance specifically the expression of an important molecule (CD169) involved in the capture and transmission of HIV-1 particles from the mucosal lumen to the submucosal compartment. Our results suggest that this mechanism may play a relevant role in sexual HIV transmission.