HIV-1 efficient entry in inner foreskin is mediated by elevated CCL5/RANTES that recruits T cells and fuels conjugate formation with Langerhans cells

Molecular mechanisms of viral oncogenesis in haematological malignancies: perspectives from metabolic reprogramming, epigenetic regulation and immune microenvironment remodeling

Haematological malignancies are one of the most common tumors, with a rising incidence noted over recent decades. Viral infections play significant roles in the pathogenesis of these malignancies globally. This review delves into the contributions of various known viruses-specifically Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), human cytomegalovirus (HCMV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human papillomavirus (HPV)-in the development of haematological malignancies. These viruses are shown to drive tumorigenesis through mechanisms, such as metabolic reprogramming, epigenetic modifications, and remodeling of the immune microenvironment. By directly disrupting fundamental cellular functions and altering metabolic and epigenetic pathways, these viruses foster an immune milieu that supports both viral persistence and tumor growth. A thorough understanding of these viral oncogenic processes is crucial not only for etiological discovery but also for developing targeted interventions. This review emphasizes the need for continued research into the specific ways these viruses manipulate the host cell's metabolic and epigenetic environments, aiming to provide insights that could guide future advancements in treatment modalities.

The spatial biology of HIV infection

HIV infection implicates a spectrum of tissues in the human body starting with viral transmission in the anogenital tract and subsequently persisting in lymphoid tissues and brain. Though studies using isolated cells have contributed significantly towards our understanding of HIV infection, the tissue microenvironment is characterised by a complex interplay of a range of factors, all of which can influence the course of infection but are otherwise missed in ex vivo studies. To address this knowledge gap, it is necessary to investigate the dynamics of infection and the host immune response in situ using imaging-based approaches. Over the last decade, emerging imaging techniques have continually redefined the limits of detection, both in terms of the scope and the scale of the targets. In doing so, this has opened up new questions that can be answered by in situ studies. This review discusses the high-dimensional imaging modalities that are now available and their application towards understanding the spatial biology of HIV infection.

The elusive male microbiome: revealing the link between the genital microbiota and fertility. Critical review and future perspectives

There is a growing focus on understanding the role of the male microbiome in fertility issues. Although research on the bacterial communities within the male reproductive system is in its initial phases, recent discoveries highlight notable variations in the microbiome's composition and abundance across distinct anatomical regions like the skin, foreskin, urethra, and coronary sulcus. To assess the relationship between male genitourinary microbiome and reproduction, we queried various databases, including MEDLINE (available via PubMed), SCOPUS, and Web of Science to obtain evidence-based data. The literature search was conducted using the following terms "gut/intestines microbiome," "genitourinary system microbiome," "microbiome and female/male infertility," "external genital tract microbiome," "internal genital tract microbiome," and "semen microbiome." Fifty-one relevant papers were analyzed, and eleven were strictly semen quality or male fertility related. The male microbiome, especially in the accessory glands like the prostate, seminal vesicles, and bulbourethral glands, has garnered significant interest because of its potential link to male fertility and reproduction. Studies have also found differences in bacterial diversity present in the testicular tissue of normozoospermic men compared to azoospermic suggesting a possible role of bacterial dysbiosis and reproduction. Correlation between the bacterial taxa in the genital microbiota of sexual partners has also been found, and sexual activity can influence the composition of the urogenital microbiota. Exploring the microbial world within the male reproductive system and its influence on fertility opens doors to developing ways to prevent, diagnose, and treat infertility. The present work emphasizes the importance of using consistent methods, conducting long-term studies, and deepening our understanding of how the reproductive tract microbiome works. This helps make research comparable, pinpoint potential interventions, and smoothly apply microbiome insights to real-world clinical practices.

The impact of sex on HIV immunopathogenesis and therapeutic interventions

Globally, the majority of people living with HIV are women or girls, but they have been a minority of participants in clinical trials and observational studies of HIV. Despite this underrepresentation, differences in the pathogenesis of HIV have been observed between men and women, with contributions from both gender- and sex-based factors. These include differences in the risk of HIV acquisition, in viral load set point and immune activation in responses to viremia, and differences in HIV reservoir maintenance. These differences obligate adequate study in both males and females in order to optimize treatments, but also provide a powerful leverage point for delineating the mechanisms of HIV pathogenesis. The shifts in exposure to sex steroid hormones across a lifespan introduce additional complexity, which again can be used to focus on either genetic or hormonal influences as the driver of an outcome. In this Review, we discuss consistent and reproducible differences by sex across the spectrum of HIV, from acquisition through pathogenesis, treatment, and cure, and explore potential mechanisms and gaps in knowledge.

Effect of cryopreservation on CD4+ T cell subsets in foreskin tissue

Voluntary medical male circumcision (VMMC) reduces HIV acquisition by at least 60%, but the determinants of HIV susceptibility in foreskin tissues are incompletely understood. Flow cytometry is a powerful tool that helps us understand tissue immune defenses in mucosal tissue like the inner foreskin, but foreskin flow cytometry has only been validated using fresh tissue samples. This restricts immune analyses to timepoints immediately after surgical acquisition and hinders research in this area. We compared fresh analysis with whole tissue cryopreservation and later thawing and digestion to analyze CD4+ T cell populations relevant to HIV susceptibility (CCR5, CD25, CD127, CCR4, CXCR3, CCR6, CCR10, HLA-DR, and CD38). Eight foreskin samples from HIV-negative males aged >18 years were collected after VMMC. For each sample, half the foreskin was immediately cryopreserved for later digestion and flow cytometry analysis, while the remaining tissues were analyzed fresh. We demonstrate no significant impact of cryopreservation on CD4+ T cell expression of CD25, CCR4, CCR6, HLA-DR, CCR10, or CD127. Although expression levels of CCR5, CD38, and CXCR3 were increased after cryopreservation, the relative ranking of participants was retained. In conclusion, cryopreserved foreskin tissues may be suitable for subsequent digestion and flow cytometry phenotyping of HIV-susceptible T cell populations.

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.

TRPV1 activation in human Langerhans cells and T cells inhibits mucosal HIV-1 infection via CGRP-dependent and independent mechanisms

Upon its mucosal transmission, HIV type 1 (HIV-1) rapidly targets genital antigen-presenting Langerhans cells (LCs), which subsequently transfer infectious virus to CD4+ T cells. We previously described an inhibitory neuroimmune cross talk, whereby calcitonin gene-related peptide (CGRP), a neuropeptide secreted by peripheral pain-sensing nociceptor neurons innervating all mucosal epithelia and associating with LCs, strongly inhibits HIV-1 transfer. As nociceptors secret CGRP following the activation of their Ca2+ ion channel transient receptor potential vanilloid 1 (TRPV1), and as we reported that LCs secret low levels of CGRP, we investigated whether LCs express functional TRPV1. We found that human LCs expressed mRNA and protein of TRPV1, which was functional and induced Ca2+ influx following activation with TRPV1 agonists, including capsaicin (CP). The treatment of LCs with TRPV1 agonists also increased CGRP secretion, reaching its anti-HIV-1 inhibitory concentrations. Accordingly, CP pretreatment significantly inhibited LCs-mediated HIV-1 transfer to CD4+ T cells, which was abrogated by both TRPV1 and CGRP receptor antagonists. Like CGRP, CP-induced inhibition of HIV-1 transfer was mediated via increased CCL3 secretion and HIV-1 degradation. CP also inhibited direct CD4+ T cells HIV-1 infection, but in CGRP-independent manners. Finally, pretreatment of inner foreskin tissue explants with CP markedly increased CGRP and CCL3 secretion, and upon subsequent polarized exposure to HIV-1, inhibited an increase in LC-T cell conjugate formation and consequently T cell infection. Our results reveal that TRPV1 activation in human LCs and CD4+ T cells inhibits mucosal HIV-1 infection, via CGRP-dependent/independent mechanisms. Formulations containing TRPV1 agonists, already approved for pain relief, could hence be useful against HIV-1.

Immune activation of vaginal human Langerhans cells increases susceptibility to HIV-1 infection

Vaginal inflammation increases the risk for sexual HIV-1 transmission but underlying mechanisms remain unclear. In this study we assessed the impact of immune activation on HIV-1 susceptibility of primary human vaginal Langerhans cells (LCs). Vaginal LCs isolated from human vaginal tissue expressed a broad range of TLRs and became activated after exposure to both viral and bacterial TLR ligands. HIV-1 replication was restricted in immature vaginal LCs as only low levels of infection could be detected. Notably, activation of immature vaginal LCs by bacterial TLR ligands increased HIV-1 infection, whereas viral TLR ligands were unable to induce HIV-1 replication in vaginal LCs. Furthermore, mature vaginal LCs transmitted HIV-1 to CD4 T cells. This study emphasizes the role for vaginal LCs in protection against mucosal HIV-1 infection, which is abrogated upon activation. Moreover, our data suggest that bacterial STIs can increase the risk of HIV-1 acquisition in women.

Women for science and science for women: Gaps, challenges and opportunities towards optimizing pre-exposure prophylaxis for HIV-1 prevention

Preventing new HIV infections remains a global challenge. Young women continue to bear a disproportionate burden of infection. Oral pre-exposure prophylaxis (PrEP), offers a novel women-initiated prevention technology and PrEP trials completed to date underscore the importance of their inclusion early in trials evaluating new HIV PrEP technologies. Data from completed topical and systemic PrEP trials highlight the role of gender specific physiological and social factors that impact PrEP uptake, adherence and efficacy. Here we review the past and current developments of HIV-1 prevention options for women with special focus on PrEP considering the diverse factors that can impact PrEP efficacy. Furthermore, we highlight the importance of inclusion of female scientists, clinicians, and community advocates in scientific efforts to further improve HIV prevention strategies.

Subtype C HIV-1 reservoirs throughout the body in ART-suppressed individuals

Subtype B HIV-1 reservoirs have been intensively investigated, but reservoirs in other subtypes and how they respond to antiretroviral therapy (ART) is substantially less established. To characterize subtype C HIV-1 reservoirs, we implemented postmortem frozen, as well as formalin fixed paraffin embedded (FFPE) tissue sampling of central nervous system (CNS) and peripheral tissues. HIV-1 LTR, gag, envelope (env) DNA and RNA was quantified using genomic DNA and RNA extracted from frozen tissues. RNAscope was used to localize subtype C HIV-1 DNA and RNA in FFPE tissue. Despite uniform viral load suppression in our cohort, PCR results showed that subtype C HIV-1 proviral copies vary both in magnitude and tissue distribution, with detection primarily in secondary lymphoid tissues. Interestingly, the appendix harbored proviruses in all subjects. Unlike subtype B, subtype C provirus was rarely detectable in the CNS, and there was no detectable HIV-1 RNA. HIV-1 RNA was detected in peripheral lymphoid tissues of 6 out of 8 ART-suppressed cases. In addition to active HIV-1 expression in lymphoid tissues, RNAscope revealed HIV RNA detection in CD4-expressing cells in the appendix, suggesting that this tissue was a previously unreported potential treatment-resistant reservoir for subtype C HIV-1.

Contribution of Sex Differences to HIV Immunology, Pathogenesis, and Cure Approaches

Approximately 38 million people were living with human immunodeficiency virus (HIV) in 2020 and 53% of those infected were female. A variety of virological and immunological sex-associated differences (sexual dimorphism) in HIV infection have been recognized in males versus females. Social, behavioral, and societal influences play an important role in how the HIV pandemic has affected men and women differently. However, biological factors including anatomical, physiologic, hormonal, and genetic differences in sex chromosomes can each contribute to the distinct characteristics of HIV infection observed in males versus females. One striking example of this is the tendency for women to have lower HIV plasma viral loads than their male counterparts early in infection, though both progress to AIDS at similar rates. Sex differences in acquisition of HIV, innate and adaptive anti-HIV immune responses, efficacy/suitability of specific antiretroviral drugs, and viral pathogenesis have all been identified. Sex differences also have the potential to affect viral persistence, latency, and cure approaches. In this brief review, we summarize the major biological male/female sex differences in HIV infection and their importance to viral acquisition, pathogenesis, treatment, and cure efforts.

HIV Latency in Myeloid Cells: Challenges for a Cure

The use of antiretroviral therapy (ART) for Human Immunodeficiency Virus (HIV) treatment has been highly successful in controlling plasma viremia to undetectable levels. However, a complete cure for HIV is hindered by the presence of replication-competent HIV, integrated in the host genome, that can persist long term in a resting state called viral latency. Resting memory CD4+ T cells are considered the biggest reservoir of persistent HIV infection and are often studied exclusively as the main target for an HIV cure. However, other cell types, such as circulating monocytes and tissue-resident macrophages, can harbor integrated, replication-competent HIV. To develop a cure for HIV, focus is needed not only on the T cell compartment, but also on these myeloid reservoirs of persistent HIV infection. In this review, we summarize their importance when designing HIV cure strategies and challenges associated to their identification and specific targeting by the “shock and kill” approach.

CGRP inhibits human Langerhans cells infection with HSV by differentially modulating specific HSV-1 and HSV-2 entry mechanisms

Herpes simplex virus (HSV) is widespread globally, with both HSV-1 and HSV-2 responsible for genital herpes. During sexual transmission, HSV targets epithelial cells, sensory peripheral pain neurons secreting the mucosal neuropeptide calcitonin gene-related peptide (CGRP), and mucosal immune cells including Langerhans cells (LCs). We previously described a neuro-immune crosstalk, whereby CGRP inhibits LCs-mediated human immunodeficiency virus type 1 (HIV-1) transmission. Herein, to further explore CGRP-mediated anti-viral function, we investigated whether CGRP affects LCs infection with HSV. We found that both HSV-1 and HSV-2 primary isolates productively infect monocyte-derived LCs (MDLCs) and inner foreskin LCs. Moreover, CGRP significantly inhibits infection with both HSV subtypes of MDLCs and langerin^high, but not langerin^low, inner foreskin LCs. For HSV-1, infection is mediated via the HSV-1-specific entry receptor 3-O sulfated heparan sulfate (3-OS HS) in a pH-depended manner, and CGRP down-regulates 3-OS HS surface expression, as well as abrogates pH dependency. For HSV-2, infection involves langerin-mediated endocytosis in a pH-independent manner, and CGRP up-regulates surface expression of atypical langerin double-trimer oligomers. Our results show that CGRP inhibits mucosal HSV infection by differentially modulating subtype-specific entry receptors and mechanisms in human LCs. CGRP could turn out useful for prevention of LCs-mediated HSV infection and HSV/HIV-1 co-infection.

Experimental Models to Study HIV Latency Reversal from Male Genital Myeloid Cells

HIV reservoirs in tissues are poorly understood and their establishment largely depends on the nature of tissues that interact with the virus. In this chapter, we will describe in vitro and ex vivo models of human urethral mucosal macrophages used in the investigation of the establishment and maintenance of tissue HIV reservoirs. In addition, we will describe how macrophage latent HIV infection was assessed in these models by reverting a nonproductive state of infection back into a productive state. Consequently, infectious particles are released to the macrophage extracellular milieu and detected by adapted viral outgrowth assays. Altogether, these approaches provide invaluable tools for the investigation on tissue-specific pathways that HIV-1 employs to reach host cells and form reservoirs in the genital mucosa. These models will contribute to the development of an efficient and targeted prophylaxis against HIV and of a HIV cure.

HIV transmitting mononuclear phagocytes; integrating the old and new

In tissue, mononuclear phagocytes (MNP) are comprised of Langerhans cells, dendritic cells, macrophages and monocyte-derived cells. They are the first immune cells to encounter HIV during transmission and transmit the virus to CD4 T cells as a consequence of their antigen presenting cell function. To understand the role these cells play in transmission, their phenotypic and functional characterisation is important. With advancements in high parameter single cell technologies, new MNPs subsets are continuously being discovered and their definition and classification is in a state of flux. This has important implications for our knowledge of HIV transmission, which requires a deeper understanding to design effective vaccines and better blocking strategies. Here we review the historical research of the role MNPs play in HIV transmission up to the present day and revaluate these studies in the context of our most recent understandings of the MNP system.

Native CGRP Neuropeptide and Its Stable Analogue SAX, But Not CGRP Peptide Fragments, Inhibit Mucosal HIV-1 Transmission

Background

The vasodilator neuropeptide calcitonin gene-related peptide (CGRP) plays both detrimental and protective roles in different pathologies. CGRP is also an essential component of the neuro-immune dialogue between nociceptors and mucosal immune cells. We previously discovered that CGRP is endowed with anti-viral activity and strongly inhibits human immunodeficiency virus type 1 (HIV-1) infection, by suppressing Langerhans cells (LCs)-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission ex-vivo. This inhibition is mediated via activation of the CGRP receptor non-canonical NFκB/STAT4 signaling pathway that induces a variety of cooperative mechanisms. These include CGRP-mediated increase in the expression of the LC-specific pathogen recognition C-type lectin langerin and decrease in LC-T-cell conjugates formation. The clinical utility of CGRP and modalities of CGRP receptor activation, for inhibition of mucosal HIV-1 transmission, remain elusive.

Methods

We tested the capacity of CGRP to inhibit HIV-1 infection in-vivo in humanized mice. We further compared the anti-HIV-1 activities of full-length native CGRP, its metabolically stable analogue SAX, and several CGRP peptide fragments containing its binding C-terminal and activating N-terminal regions. These agonists were evaluated for their capacity to inhibit LCs-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission in human mucosal tissues ex-vivo.

Results

A single CGRP intravaginal topical treatment of humanized mice, followed by HIV-1 vaginal challenge, transiently restricts the increase in HIV-1 plasma viral loads but maintains long-lasting higher CD4+ T-cell counts. Similarly to CGRP, SAX inhibits LCs-mediated HIV-1 trans-infection in-vitro, but with lower potency. This inhibition is mediated via CGRP receptor activation, leading to increased expression of both langerin and STAT4 in LCs. In contrast, several N-terminal and N+C-terminal bivalent CGRP peptide fragments fail to increase langerin and STAT4, and accordingly lack anti-HIV-1 activities. Finally, like CGRP, treatment of human inner foreskin tissue explants with SAX, followed by polarized inoculation with cell-associated HIV-1, completely blocks formation of LC-T-cell conjugates and HIV-1 infection of T-cells.

Conclusion

Our results show that CGRP receptor activation by full-length CGRP or SAX is required for efficient inhibition of LCs-mediated mucosal HIV-1 transmission. These findings suggest that formulations containing CGRP, SAX and/or their optimized agonists/analogues could be harnessed for HIV-1 prevention.

Semen: A modulator of female genital tract inflammation and a vector for HIV-1 transmission

In order to establish productive infection in women, HIV must transverse the vaginal epithelium and gain access to local target cells. Genital inflammation contributes to the availability of HIV susceptible cells at the female genital mucosa and is associated with higher HIV transmission rates in women. Factors that contribute to genital inflammation may subsequently increase the risk of HIV infection in women. Semen is a highly immunomodulatory fluid containing several bioactive molecules with the potential to influence inflammation and immune activation at the female genital tract. In addition to its role as a vector for HIV transmission, semen induces profound mucosal changes to prime the female reproductive tract for conception. Still, most studies of mucosal immunity are conducted in the absence of semen or without considering its immune impact on the female genital tract. This review discusses the various mechanisms by which semen exposure may influence female genital inflammation and highlights the importance of routine screening for semen biomarkers in vaginal specimens to account for its impact on genital inflammation.

Preventive HIV Vaccines-Leveraging on Lessons from the Past to Pave the Way Forward

Almost four decades on, since the 1980’s, with hundreds of HIV vaccine candidates tested in both non-human primates and humans, and several HIV vaccines trials later, an efficacious HIV vaccine continues to evade us. The enormous worldwide genetic diversity of HIV, combined with HIV’s inherent recombination and high mutation rates, has hampered the development of an effective vaccine. Despite the advent of antiretrovirals as pre-exposure prophylaxis and preventative treatment, which have shown to be effective, HIV infections continue to proliferate, highlighting the great need for a vaccine. Here, we provide a brief history for the HIV vaccine field, with the most recent disappointments and advancements. We also provide an update on current passive immunity trials, testing proof of the concept of the most clinically advanced broadly neutralizing monoclonal antibodies for HIV prevention. Finally, we include mucosal immunity, the importance of vaccine-elicited immune responses and the challenges thereof in the most vulnerable environment–the female genital tract and the rectal surfaces of the gastrointestinal tract for heterosexual and men who have sex with men transmissions, respectively.

Circumcision as an Intervening Strategy against HIV Acquisition in the Male Genital Tract

Unsafe sex with HIV-infected individuals remains a major route for HIV transmission, and protective strategies, such as the distribution of free condoms and pre-or post-prophylaxis medication, have failed to control the spread of HIV, particularly in resource-limited settings and high HIV prevalence areas. An additional key strategy for HIV prevention is voluntary male circumcision (MC). International health organizations (e.g., the World Health Organization, UNAIDS) have recommended this strategy on a larger scale, however, there is a general lack of public understanding about how MC effectively protects against HIV infection. This review aims to discuss the acquisition of HIV through the male genital tract and explain how and why circumcised men are more protected from HIV infection during sexual activity than uncircumcised men who are at higher risk of HIV acquisition.

An IRF1-IRF4 Toggle-Switch Controls Tolerogenic and Immunogenic Transcriptional Programming in Human Langerhans Cells

Langerhans cells (LCs) reside in the epidermis as a dense network of immune system sentinels, coordinating both immunogenic and tolerogenic immune responses. To determine molecular switches directing induction of LC immune activation, we performed mathematical modelling of gene regulatory networks identified by single cell RNA sequencing of LCs exposed to TNF-alpha, a key pro-inflammatory signal produced by the skin. Our approach delineated three programmes of LC phenotypic activation (immunogenic, tolerogenic or ambivalent), and confirmed that TNF-alpha enhanced LC immunogenic programming. Through regulon analysis followed by mutual information modelling, we identified IRF1 as the key transcription factor for the regulation of immunogenicity in LCs. Application of a mathematical toggle switch model, coupling IRF1 with tolerance-inducing transcription factors, determined the key set of transcription factors regulating the switch between tolerance and immunogenicity, and correctly predicted LC behaviour in LCs derived from different body sites. Our findings provide a mechanistic explanation of how combinatorial interactions between different transcription factors can coordinate specific transcriptional programmes in human LCs, interpreting the microenvironmental context of the local tissue microenvironments.

Oncogenic Effects of HIV-1 Proteins, Mechanisms Behind

People living with human immunodeficiency virus (HIV-1) are at increased risk of developing cancer, such as Kaposi sarcoma (KS), non-Hodgkin lymphoma (NHL), cervical cancer, and other cancers associated with chronic viral infections. Traditionally, this is linked to HIV-1-induced immune suppression with depletion of CD4+ T-helper cells, exhaustion of lymphopoiesis and lymphocyte dysfunction. However, the long-term successful implementation of antiretroviral therapy (ART) with an early start did not preclude the oncological complications, implying that HIV-1 and its antigens are directly involved in carcinogenesis and may exert their effects on the background of restored immune system even when present at extremely low levels. Experimental data indicate that HIV-1 virions and single viral antigens can enter a wide variety of cells, including epithelial. This review is focused on the effects of five viral proteins: envelope protein gp120, accessory protein negative factor Nef, matrix protein p17, transactivator of transcription Tat and reverse transcriptase RT. Gp120, Nef, p17, Tat, and RT cause oxidative stress, can be released from HIV-1-infected cells and are oncogenic. All five are in a position to affect "innocent" bystander cells, specifically, to cause the propagation of (pre)existing malignant and malignant transformation of normal epithelial cells, giving grounds to the direct carcinogenic effects of HIV-1.

The CH1α domain of mucosal gp41 IgA contributes to antibody specificity and antiviral functions in HIV-1 highly exposed Sero-Negative individuals

The antibody molecule comprises a variable domain conferring antigen specificity and affinity distinct from the heavy chain constant (CH) domains dictating effector functions. We here interrogate this paradigm by evaluating the unique influence of the CH1α domain on epitope specificity and functions using two mucosal gp41-specific Fab-IgAs (FabA) derived from HIV-1 highly-exposed but persistently seronegative individuals (HESN). These HESN develop selectively affinity-matured HIV-1-specific mucosal IgA that target the gp41 viral envelope and might provide protection although by unclear mechanisms. Isotype-switching FabAs into Fab-IgGs (FabGs) results in a >10-fold loss in affinity for HIV-1 clade A, B, and C gp41, together with reduced neutralization of HIV-1 cross-clade. The FabA conformational epitopes map selectively on gp41 in 6-Helix bundle and pre-fusion conformations cross-clade, unlike FabGs. Finally, we designed in silico, a 12 amino-acid peptide recapitulating one FabA conformational epitope that inhibits the FabA binding to gp41 cross-clade and its neutralizing activity. Altogether, our results reveal that the CH1α domain shapes the antibody paratope through an allosteric effect, thereby strengthening the antibody specificity and functional activities. Further, they clarify the mechanisms by which these HESN IgAs might confer protection against HIV-1-sexual acquisition. The IgA-specific epitope we characterized by reverse vaccinology could help designing a mucosal HIV-1 vaccine.

Human immunodeficiency virus interaction with oral and genital mucosal epithelia may lead to epithelial-mesenchymal transition and sequestration of virions in the endosomal compartments

Oral and genital mucosal epithelia are multistratified epithelial barriers with well-developed tight and adherens junctions. These barriers serve as the first line of defense against many pathogens, including human immunodeficiency virus (HIV). HIV interaction with the surface of mucosal epithelial cells, however, may activate transforming growth factor-beta (TGF-β) and mitogen-activated protein kinase signaling pathways. When activated, these pathways may lead to the disruption of epithelial junctions and epithelial-mesenchymal transition (EMT). HIV-induced impairment of the mucosal barrier may facilitate the spread of pathogenic viral, bacterial, fungal, and other infectious agents. HIV-induced EMT promotes highly motile/migratory cells. In oral and genital mucosa, if EMT occurs within a human papillomavirus (HPV)-infected premalignant or malignant cell environment, the HPV-associated neoplastic process could be accelerated by promoting viral invasion of malignant cells. HIV also internalizes into oral and genital mucosal epithelial cells. The majority (90%) of internalized virions do not cross the epithelium, but are retained in endosomal compartments for several days. These sequestered virions are infectious. Upon interaction with activated peripheral blood mononuclear cells and CD4+ T lymphocytes, epithelial cells containing the virus can be transferred. The induction of HIV-1 release and the cell-to-cell spread of virus from epithelial cells to lymphocytes is mediated by interaction of lymphocyte receptor function-associated antigen-1 with the epithelial cell receptor intercellular adhesion molecule-1. Thus, mucosal epithelial cells may serve as a transient reservoir for HIV, which could play a critical role in viral transmission.

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.

HSV-2 Cellular Programming Enables Productive HIV Infection in Dendritic Cells

Genital herpes is a common sexually transmitted infection caused by herpes simplex virus type 2 (HSV-2). Genital herpes significantly enhances the acquisition and transmission of HIV-1 by creating a microenvironment that supports HIV infection in the host. Dendritic cells (DCs) represent one of the first innate cell types that encounter HIV-1 and HSV-2 in the genital mucosa. HSV-2 infection has been shown to modulate DCs, rendering them more receptive to HIV infection. Here, we investigated the potential mechanisms underlying HSV-2-mediated augmentation of HIV-1 infection. We demonstrated that the presence of HSV-2 enhanced productive HIV-1 infection of DCs and boosted inflammatory and antiviral responses. The HSV-2 augmented HIV-1 infection required intact HSV-2 DNA, but not active HSV-2 DNA replication. Furthermore, the augmented HIV infection of DCs involved the cGAS-STING pathway. Interestingly, we could not see any involvement of TLR2 or TLR3 nor suppression of infection by IFN-β production. The conditioning by HSV-2 in dual exposed DCs decreased protein expression of IFI16, cGAS, STING, and TBK1, which is associated with signaling through the STING pathway. Dual exposure to HSV-2 and HIV-1 gave decreased levels of several HIV-1 restriction factors, especially SAMHD1, TREX1, and APOBEC3G. Activation of the STING pathway in DCs by exposure to both HSV-2 and HIV-1 most likely led to the proteolytic degradation of the HIV-1 restriction factors SAMHD1, TREX1, and APOBEC3G, which should release their normal restriction of HIV infection in DCs. This released their normal restriction of HIV infection in DCs. We showed that HSV-2 reprogramming of cellular signaling pathways and protein expression levels in the DCs provided a setting where HIV-1 can establish a higher productive infection in the DCs. In conclusion, HSV-2 reprogramming opens up DCs for HIV-1 infection and creates a microenvironment favoring HIV-1 transmission.

HIV-1 Reverse Transcriptase Promotes Tumor Growth and Metastasis Formation via ROS-Dependent Upregulation of Twist

HIV-induced immune suppression results in the high prevalence of HIV/AIDS-associated malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer. HIV-infected people are also at an increased risk of "non-AIDS-defining" malignancies not directly linked to immune suppression but associated with viral infections. Their incidence is increasing despite successful antiretroviral therapy. The mechanism behind this phenomenon remains unclear. Here, we obtained daughter clones of murine mammary gland adenocarcinoma 4T1luc2 cells expressing consensus reverse transcriptase of HIV-1 subtype A FSU_A strain (RT_A) with and without primary mutations of drug resistance. In in vitro tests, mutations of resistance to nucleoside inhibitors K65R/M184V reduced the polymerase, and to nonnucleoside inhibitors K103N/G190S, the RNase H activities of RT_A. Expression of these RT_A variants in 4T1luc2 cells led to increased production of the reactive oxygen species (ROS), lipid peroxidation, enhanced cell motility in the wound healing assay, and upregulation of expression of Vimentin and Twist. These properties, particularly, the expression of Twist, correlated with the levels of expression RT_A and/or the production of ROS. When implanted into syngeneic BALB/C mice, 4T1luc2 cells expressing nonmutated RT_A demonstrated enhanced rate of tumor growth and increased metastatic activity, dependent on the level of expression of RT_A and Twist. No enhancement was observed for the clones expressing mutated RT_A variants. Plausible mechanisms are discussed involving differential interactions of mutated and nonmutated RTs with its cellular partners involved in the regulation of ROS. This study establishes links between the expression of HIV-1 RT, production of ROS, induction of EMT, and enhanced propagation of RT-expressing tumor cells. Such scenario can be proposed as one of the mechanisms of HIV-induced/enhanced carcinogenesis not associated with immune suppression.

Biologic interactions between HSV-2 and HIV-1 and possible implications for HSV vaccine development

Development of a safe and effective vaccine against herpes simplex virus type 2 (HSV-2) has the potential to limit the global burden of HSV-2 infection and disease, including genital ulcer disease and neonatal herpes, and is a global sexual and reproductive health priority. Another important potential benefit of an HSV-2 vaccine would be to decrease HIV infections, as HSV-2 increases the risk of HIV-1 acquisition several-fold. Acute and chronic HSV-2 infection creates ulcerations and draws dendritic cells and activated CD4+ T cells into genital mucosa. These cells are targets for HIV entry and replication. Prophylactic HSV-2 vaccines (to prevent infection) and therapeutic vaccines (to modify or treat existing infections) are currently under development. By preventing or modifying infection, an effective HSV-2 vaccine could limit HSV-associated genital mucosal inflammation and thus HIV risk. However, a vaccine might have competing effects on HIV risk depending on its mechanism of action and cell populations generated in the genital mucosa. In this article, we review biologic interactions between HSV-2 and HIV-1, consider HSV-2 vaccine development in the context of HIV risk, and discuss implications and research needs for future HSV vaccine development.

Voluntary medical male circumcision and HIV in Zambia: expectations and observations

The study analysed the HIV/AIDS situation in Zambia six years after the onset of mass campaigns of Voluntary Medical Male Circumcision (VMMC). The analysis was based on data from Demographic and Health Surveys (DHS) conducted in 2001, 2007 and 2013. Results show that HIV prevalence among men aged 15-29 (the target group for VMMC) did not decrease over the period, despite a decline in HIV prevalence among women of the same age group (most of their partners). Correlations between male circumcision and HIV prevalence were positive for a variety of socioeconomic groups (urban residence, province of residence, level of education, ethnicity). In a multivariate analysis, based on the 2013 DHS survey, circumcised men were found to have the same level of infection as uncircumcised men, after controlling for age, sexual behaviour and socioeconomic status. Lastly, circumcised men tended to have somewhat riskier sexual behaviour than uncircumcised men. This study, based on large representative samples of the Zambian population, questions the current strategy of mass circumcision campaigns in southern and eastern Africa.

Characterization of CD4+ T cell subsets and HIV susceptibility in the inner and outer foreskin of Ugandan men

PROBLEM

Biological mechanisms of foreskin HIV acquisition are poorly defined. The inner foreskin is preferentially infected in explant models, so we hypothesized that this site would be enriched for HIV-susceptible CD4⁺ T cells and proinflammatory/chemoattractant cytokines.

METHOD OF STUDY

A total of 42 HIV-uninfected Ugandan men without genital symptoms provided foreskin tissues and swabs at the time of elective penile circumcision. The immune phenotype of foreskin-derived CD4⁺ T cells and entry of a CCR5-tropic HIV pseudovirus was characterized, and specific cytokine levels assayed by multiplexed chemiluminescent ELISA.

RESULTS

Unexpectedly, outer foreskin CD4⁺ T cells more frequently expressed CCR5 (median 29.2% vs 22.9%, P = 0.01) and CD69 (median 36.5% vs 15%, P < 0.01), and on a per-cell basis, HIV entry was higher. However, overall CD4⁺ T cell density was approximately twofold higher in the inner foreskin, and several highly susceptible T cell subsets were increased at this site, including Th17 cells (20.0% vs 14.1%, P = 0.0021). Specific pro-inflammatory cytokine levels were also higher on the inner foreskin surface (IL-17, IL-8, RANTES and IL-1β; all P < 0.05).

CONCLUSION

There was marked heterogeneity in CD4⁺ T cell populations and immune milieu between inner and outer foreskin tissues. Despite higher per-cell viral entry into CD4⁺ T cells from the outer foreskin, the higher target cell density and enriched pro-inflammatory cytokines of the inner foreskin suggest that this may be a preferential site for HIV acquisition.

Human Dendritic Cell Subsets, Ontogeny, and Impact on HIV Infection

Dendritic cells (DCs) play important roles in orchestrating host immunity against invading pathogens, representing one of the first responders to infection by mucosal invaders. From their discovery by Ralph Steinman in the 1970s followed shortly after with descriptions of their in vivo diversity and distribution by Derek Hart, we are still continuing to progressively elucidate the spectrum of DCs present in various anatomical compartments. With the power of high-dimensional approaches such as single-cell sequencing and multiparameter cytometry, recent studies have shed new light on the identities and functions of DC subtypes. Notable examples include the reclassification of plasmacytoid DCs as purely interferon-producing cells and re-evaluation of intestinal conventional DCs and macrophages as derived from monocyte precursors. Collectively, these observations have changed how we view these cells not only in steady-state immunity but also during disease and infection. In this review, we will discuss the current landscape of DCs and their ontogeny, and how this influences our understanding of their roles during HIV infection.

The role of Langerhans cells in pathologies of the skin

Langerhans cells (LCs) are epidermal immune cells of myeloid origin. Although these cells were primarily thought to play a defensive role in the skin, evidence now indicates a diverse range of LC-mediated effects including the relay of viral antigens in herpes simplex infection, recruitment of eosinophils in atopic dermatitis and promotion of a Th17 response in Candida infection. LCs may have a protective or suppressive function in pathologies of the skin, with differing functions being driven by the skin milieu. Understanding LC function will help guide the development of interventions that modulate these cells for therapeutic benefit.

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.

HIV-1 reservoirs in urethral macrophages of patients under suppressive antiretroviral therapy

Human immunodeficiency virus type 1 (HIV-1) eradication is prevented by the establishment on infection of cellular HIV-1 reservoirs that are not fully characterized, especially in genital mucosal tissues (the main HIV-1 entry portal on sexual transmission). Here, we show, using penile tissues from HIV-1-infected individuals under suppressive combination antiretroviral therapy, that urethral macrophages contain integrated HIV-1 DNA, RNA, proteins and intact virions in virus-containing compartment-like structures, whereas viral components remain undetectable in urethral T cells. Moreover, urethral cells specifically release replication-competent infectious HIV-1 following reactivation with the macrophage activator lipopolysaccharide, while the T-cell activator phytohaemagglutinin is ineffective. HIV-1 urethral reservoirs localize preferentially in a subset of polarized macrophages that highly expresses the interleukin-1 receptor, CD206 and interleukin-4 receptor, but not CD163. To our knowledge, these results are the first evidence that human urethral tissue macrophages constitute a principal HIV-1 reservoir. Such findings are determinant for therapeutic strategies aimed at HIV-1 eradication.

Short Communication: Decreased Plasma Calcitonin Gene-Related Peptide as a Novel Biomarker for HIV-1 Disease Progression

HIV-1 mucosal transmission in genital epithelia occurs through infection of Langerhans cells and subsequent transinfection of CD4⁺ T cells. We previously reported that the vasodilator neuropeptide calcitonin gene-related peptide (CGRP), secreted upon activation of sensory peripheral neurons that innervate all mucosal epithelia, significantly inhibits transinfection. To investigate the association between CGRP and HIV-1 during infection, we evaluated circulating CGRP levels in HIV-1-infected patients. Plasma was obtained from combination antiretroviral therapy (cART)-naive or cART-treated patients with primary/acute (PHI) or chronic (CHI) HIV-1 infection, as well as from individuals who naturally control HIV-1 infection, namely exposed seronegatives (ESNs), elite controllers (ECs), and long-term nonprogressors (LTNPs). CGRP plasma levels were measured using an enzyme immunoassay. Compared with healthy HIV-1-negative controls, CGRP plasma levels significantly decreased in PHI patients and even further in CHI patients, but remained unchanged in ESNs, ECs, and LTNPs. Moreover, CGRP plasma levels were restored to baseline upon cART in both PHI and CHI. Finally, CGRP plasma levels directly correlated with CD4⁺ T cell counts and inversely with viral loads. Altogether, CGRP could serve as a novel diagnostic plasma biomarker for progression of HIV-1 infection. Moreover, administration of CGRP to cART-naive HIV-1-infected patients, to compensate for CGRP decline, could help controlling on-going HIV-1 infection.

Mucosal Vaccine Approaches for Prevention of HIV and SIV Transmission

Optimal protective immunity to HIV will likely require that plasma cells, memory B cells and memory T cells be stationed in mucosal tissues at portals of viral entry. Mucosal vaccine administration is more effective than parenteral vaccine delivery for this purpose. The challenge has been to achieve efficient vaccine uptake at mucosal surfaces, and to identify safe and effective adjuvants, especially for mucosally administered HIV envelope protein immunogens. Here, we discuss strategies used to deliver potential HIV vaccine candidates in the intestine, respiratory tract, and male and female genital tract of humans and nonhuman primates. We also review mucosal adjuvants, including Toll-like receptor agonists, which may adjuvant both mucosal humoral and cellular immune responses to HIV protein immunogens.

Seminal Simian Immunodeficiency Virus in Chronically Infected Cynomolgus Macaques Is Dominated by Virus Originating from Multiple Genital Organs

The sexual transmission of viruses is responsible for the spread of multiple infectious diseases. Although the human immunodeficiency virus (HIV)/AIDS pandemic remains fueled by sexual contacts with infected semen, the origin of virus in semen is still unknown. In a substantial number of HIV-infected men, viral strains present in semen differ from the ones in blood, suggesting that HIV is locally produced within the genital tract. Such local production may be responsible for the persistence of HIV in semen despite effective antiretroviral therapy. In this study, we used single-genome amplification, amplicon sequencing (env gene), and phylogenetic analyses to compare the genetic structures of simian immunodeficiency virus (SIV) populations across all the male genital organs and blood in intravenously inoculated cynomolgus macaques in the chronic stage of infection. Examination of the virus populations present in the male genital tissues of the macaques revealed compartmentalized SIV populations in testis, epididymis, vas deferens, seminal vesicles, and urethra. We found genetic similarities between the viral strains present in semen and those in epididymis, vas deferens, and seminal vesicles. The contribution of male genital organs to virus shedding in semen varied among individuals and could not be predicted based on their infection or proinflammatory cytokine mRNA levels. These data indicate that rather than a single source, multiple genital organs are involved in the release of free virus and infected cells into semen. These findings have important implications for our understanding of systemic virus shedding and persistence in semen and for the design of eradication strategies to access viral reservoirs.

IMPORTANCE Semen is instrumental for the dissemination of viruses through sexual contacts. Worryingly, a number of systemic viruses, such as HIV, can persist in this body fluid in the absence of viremia. The local source(s) of virus in semen, however, remains unknown. To elucidate the anatomic origin(s) of the virus released in semen, we compared viral populations present in semen with those in the male genital organs and blood of the Asian macaque model, using single-genome amplification, amplicon sequencing (env gene), and phylogenetic analysis. Our results show that multiple genital tissues harbor compartmentalized strains, some of them (i.e., from epididymis, vas deferens, and seminal vesicles) displaying genetic similarities with the viral populations present in semen. This study is the first to uncover local genital sources of viral populations in semen, providing a new basis for innovative targeted strategies to prevent and eradicate HIV in the male genital tract.

HIV internalization into oral and genital epithelial cells by endocytosis and macropinocytosis leads to viral sequestration in the vesicles

Recently, we showed that HIV-1 is sequestered, i.e., trapped, in the intracellular vesicles of oral and genital epithelial cells. Here, we investigated the mechanisms of HIV-1 sequestration in vesicles of polarized tonsil, foreskin and cervical epithelial cells. HIV-1 internalization into epithelial cells is initiated by multiple entry pathways, including clathrin-, caveolin/lipid raft-associated endocytosis and macropinocytosis. Inhibition of HIV-1 attachment to galactosylceramide and heparan sulfate proteoglycans, and virus endocytosis and macropinocytosis reduced HIV-1 sequestration by 30-40%. T-cell immunoglobulin and mucin domain 1 (TIM-1) were expressed on the apical surface of polarized tonsil, cervical and foreskin epithelial cells. However, TIM-1-associated HIV-1 macropinocytosis and sequestration were detected mostly in tonsil epithelial cells. Sequestered HIV-1 was resistant to trypsin, pronase, and soluble CD4, indicating that the sequestered virus was intracellular. Inhibition of HIV-1 intraepithelial sequestration and elimination of vesicles containing virus in the mucosal epithelium may help in the prevention of HIV-1 mucosal transmission.

The HIV-1 viral synapse signals human foreskin keratinocytes to secrete thymic stromal lymphopoietin facilitating HIV-1 foreskin entry

The complexity of signal transduction resulting from the contact of human immunodeficiency virus type 1 (HIV-1)-infected cells and mucosal cells has hampered our comprehension of HIV-1 mucosal entry. Such process is driven efficiently only by viral synapse contacts, whereas cell-free HIV-1 remains poorly infectious. Using CD4⁺ T-cells expressing only HIV-1 envelope inoculated on human adult foreskin tissues, we designed methodologies to identify the signals transduced in foreskin keratinocytes following HIV-1-envelope-dependent viral synapse formation. We find that the viral synapse activates the MyD88-independent TLR-4-nuclear factor (NfκB) signaling pathway in keratinocytes and the subsequent secretion of cytokines including thymic stromal lymphopoietin (TSLP), a cytokine linking innate and T-helper type 2-adaptive immune responses. Moreover, the viral synapse upregulates the non-coding microRNA miR-375, known to control TSLP, and transfection of keratinocytes with anti-miR-375 blocks significantly TSLP secretion. Thus, the secretion of TSLP by keratinocytes is induced by the viral synapse in a miR-375 controlled manner. At the tissue level, these signals translate into the epidermal redistribution of Langerhans cells and formation of conjugates with T-cells, recapitulating the initial events observed in human foreskin infection by HIV-1. These results open new possibilities for designing strategies to block mucosal HIV-1 transmission, the major pathway by which HIV-1 spreads worldwide.

The Human Penis Is a Genuine Immunological Effector Site

The human penis is a main portal of entry for numerous pathogens, and vaccines able to control resulting infections locally are highly desirable. However, in contrast to the gastrointestinal or vaginal mucosa, the penile immune system and mechanisms inducing a penile immune response remain elusive. In this descriptive study, using multiparametric flow cytometry and immunohistochemistry, we characterized mucosal immune cells such as B, T, and natural killer (NK) cells from the urethra, fossa, and glans of human adult penile tissues. We show that memory B lymphocytes and CD138⁺ plasma cells are detected in all penile compartments. CD4⁺ and CD8⁺ T lymphocytes reside in the epithelium and lamina propria of the penile regions and have mostly a resting memory phenotype. All penile regions contain CD56^dim NK cells surface expressing the natural cytotoxicity receptor NKp44 and the antibody-dependent cell cytotoxicity receptor CD16. These cells are also able to spontaneously secrete pro- and anti-inflammatory cytokines, such as IL-17 and IL-22. Finally, CCR10 is the main homing receptor detected in these penile cells although, together with CCR3, CCR6, and CCR9, their expression level differs between penile compartments. Unlike antigen-presenting cells which type differ between penile regions as we reported earlier, urethral, fossa, and glans content in immune B, T, and NK cells is comparable. However, median values per each analysis suggest that the glans, containing higher number and more activated NK cells together with higher number of terminally differentiate effector CD8⁺ T cells, is a superior effector site than the urethra and the fossa. Thus, the human penis is an immunologically active tissue containing the cellular machinery required to induce and produce a specific and effective response against mucosal pathogens. It can therefore be considered as a classic mucosal effector site, a feature that must be taken into account for the elaboration of efficient strategies, including vaccines, against sexually transmitted infections.

Calcitonin Gene-Related Peptide Induces HIV-1 Proteasomal Degradation in Mucosal Langerhans Cells

The neuroimmune dialogue between peripheral neurons and Langerhans cells (LCs) within mucosal epithelia protects against incoming pathogens. LCs rapidly internalize human immunodeficiency virus type 1 (HIV-1) upon its sexual transmission and then trans-infect CD4⁺ T cells. We recently found that the neuropeptide calcitonin gene-related peptide (CGRP), secreted mucosally from peripheral neurons, inhibits LC-mediated HIV-1 trans-infection. In this study, we investigated the mechanism of CGRP-induced inhibition, focusing on HIV-1 degradation in LCs and its interplay with trans-infection. We first show that HIV-1 degradation occurs in endolysosomes in untreated LCs, and functionally blocking such degradation with lysosomotropic agents results in increased trans-infection. We demonstrate that CGRP acts via its cognate receptor and at a viral postentry step to induce faster HIV-1 degradation, but without affecting the kinetics of endolysosomal degradation. We reveal that unexpectedly, CGRP shifts HIV-1 degradation from endolysosomes toward the proteasome, providing the first evidence for functional HIV-1 proteasomal degradation in LCs. Such efficient proteasomal degradation significantly inhibits the first phase of trans-infection, and proteasomal, but not endolysosomal, inhibitors abrogate CGRP-induced inhibition. Together, our results establish that CGRP controls the HIV-1 degradation mode in LCs. The presence of endogenous CGRP within innervated mucosal tissues, especially during the sexual response, to which CGRP contributes, suggests that HIV-1 proteasomal degradation predominates in vivo Hence, proteasomal, rather than endolysosomal, HIV-1 degradation in LCs should be enhanced clinically to effectively restrict HIV-1 trans-infection.IMPORTANCE During sexual transmission, HIV-1 is internalized and degraded in LCs, the resident antigen-presenting cells in mucosal epithelia. Yet during trans-infection, infectious virions escaping degradation are transferred to CD4⁺ T cells, the principal HIV-1 targets. We previously found that the neuroimmune dialogue between LCs and peripheral neurons, innervating mucosal epithelia, significantly inhibits trans-infection via the action of the secreted neuropeptide CGRP on LCs. In this study, we investigated whether CGRP-induced inhibition of trans-infection is linked to CGRP-controlled HIV-1 degradation in LCs. We show that in untreated LCs, HIV-1 is functionally degraded in endolysosomes. In sharp contrast, we reveal that in CGRP-treated LCs, HIV-1 is diverted toward and degraded via another cytosolic protein degradative pathway, namely, the proteasome. These results establish that CGRP regulates HIV-1 degradation in LCs. As CGRP contributes to the sexual response and present within mucosal epithelia, HIV-1 proteasomal degradation in LCs might predominate in vivo and should be enhanced clinically.

Penile coital injuries in men decline after circumcision: Results from a prospective study of recently circumcised and uncircumcised men in western Kenya

Background

Penile coital injuries are one of the suggested mechanisms behind the increased risk of HIV among uncircumcised men. We evaluated the prevalence and correlates of self-reported penile coital injuries in a longitudinal community-based cohort of young (18–24 years old), newly circumcised and uncircumcised men in Western Kenya.

Methods

Self-reported penile coital injuries were assessed at baseline, 6, 12, 18 and 24 months of follow-up, and were defined as scratches, cuts or abrasions during sex, penile soreness during sex, and skin of the penis bleeding during sex. Associations between penile coital injuries, circumcision, sexual satisfaction, and other covariates were estimated with mixed effect models.

Results

Between November 2008 and April 2010 3,186 participants were enrolled (1,588 into circumcision group and 1,598 as age-matched controls). Among 2,106 (66%) participants sexually active at baseline, 53% reported any penile injury, including 44% scratches, cuts or abrasions; 32% penile pain/soreness; and 22% penile bleeding. In multivariable modeling, risk was lower for circumcised men than uncircumcised men for scratches, cuts and abrasions (aOR = 0.39; 95% CI 0.34–0.44); penile pain/soreness (aOR = 0.58; 95% CI 0.51–0.65), penile bleeding (aOR = 0.53; 95% CI 0.46–0.62), and any penile coital injuries (aOR = 0.47; 95%CI 0.42–0.53). Other significant risk factors included increasing age, history of STIs and genital sores, and multiple sex partners, while condom use was protective. Coital injuries were significantly associated with lower levels of sexual satisfaction in longitudinal analyses (scratches, cuts or abrasions: aOR = 0.87, 95% CI: 0.76–0.98; penile pain/soreness: aOR = 0.82, 95% CI: 0.72–0.93; and penile bleeding: aOR = 0.65, 95% CI: 0.55–0.76).

Conclusions

Self-reported penile coital injuries were common and decreased significantly following circumcision. Improving sexual experience through the removal of a potential source of sexual discomfort may resonate with many men targeted for circumcision services. The role of penile coital injuries in sexual satisfaction, HIV, HSV-2, and as a motivator for seeking circumcision services should be explored further.

The biology of how circumcision reduces HIV susceptibility: broader implications for the prevention field

Circumcision reduces heterosexual HIV-1 acquisition in men by at least 60%. However, the biological mechanisms by which circumcision is protective remain incompletely understood. We test the hypothesis that the sub-preputial microenvironment created by the foreskin drives immune activation in adjacent foreskin tissues, facilitating HIV-1 infection through a combination of epithelial barrier disruption, enhanced dendritic cell maturation, and the recruitment/activation of neutrophils and susceptible CD4 T cell subsets such as Th17 cells. Furthermore, we provide evidence that the genital microbiome may be an important driver of this immune activation. This suggests that new modalities to reduce genital immune activation and/or alter the genital microbiome, used alone or in combination with topical microbicides, may be of significant benefit to HIV prevention.

G2-S16 dendrimer as a candidate for a microbicide to prevent HIV-1 infection in women

Unprotected heterosexual intercourse is the first route for sustaining the global spread of human immunodeficiency virus type 1 (HIV-1), being responsible for 80% of new HIV-1 infections in the world. The presence of inflammation in the female reproductive tract and the presence of semen increases the risk of heterosexual HIV-1 transmission. This state-of-the-art research based on an innovative nanotechnology design was focused on a toxicological study of the limitation of the activity of the novel H₂O-soluble anionic carbosilane dendrimer G2-S16 in the adult cervical and foreskin epithelia. The G2-S16 dendrimer did not cause any irritation or inflammation in the vaginal epithelium, proving that this dendrimer is a safe nanocompound for vaginal application to control viral transmission. It was shown that no significant differences were found in mortality, sublethal or teratogenic effects when the zebra fish embryos were treated with G2-S16. In short, G2-S16 seems to be an ideal candidate for the development of a topical microbicide against HIV-1 infection and the next step is try in clinical trials, because of its great in vivo biocompatibility, as well as its ability to halt HIV-1 infection in the presence of semen.

Immunological function of Langerhans cells in HIV infection

BACKGROUND

Langerhans cells (LCs) are one of the initial target cells for HIV following sexual exposure and they are productively infected by HIV. HIV-infected LCs migrate to the draining lymph nodes (dLNs) and transmit the virus to CD4⁺ T cells, leading to the dissemination of HIV. In contrast with the role of LCs in initial HIV acquisition, little is known about the modulation of immune responses by HIV-infected LCs.

OBJECTIVE

We aimed to elucidate the induction of HIV-specific CD8⁺ T cells and regulatory T cells (Tregs), both of which play important roles in regulating the progression of HIV infection.

METHODS

We examined the inducibility of HLA-A*0201 restricted HIV-specific CD8⁺ T cells and Tregs by HIV-primed LCs or HIV-primed dendritic cells (DCs) as a control.

RESULTS

The number of HIV-specific CD8⁺ T cells induced by HIV-primed monocyte-derived LCs (mLCs) was significantly higher than that by HIV-primed monocyte-derived DCs (mDCs). Additionally, HIV-specific CD8⁺ T cells induced by HIV-primed mLCs produced more IFN-γ than HIV-nonspecific CD8⁺ T cells. HIV-primed human epidermal LCs also induced IFN-γ-producing HIV-specific CD8⁺ T cells. As for the induction of Tregs, HIV-primed mLCs and human epidermal LCs significantly impaired the induction of FoxP3^hiCD45RA^- effector Tregs than HIV-unprimed mLCs and human epidermal LCs.

CONCLUSIONS

HIV-primed LCs trigger beneficial immune responses against HIV infection through the increased induction of HIV-specific CD8⁺ T cells and the decreased induction of effector Tregs in the initial phase of HIV infection, thereby contributing to the prolonged onset of AIDS.

Release of HIV-1 sequestered in the vesicles of oral and genital mucosal epithelial cells by epithelial-lymphocyte interaction

Oropharyngeal mucosal epithelia of fetuses/neonates/infants and the genital epithelia of adults play a critical role in HIV-1 mother-to-child transmission and sexual transmission of virus, respectively. To study the mechanisms of HIV-1 transmission through mucosal epithelium, we established polarized tonsil, cervical and foreskin epithelial cells. Analysis of HIV-1 transmission through epithelial cells showed that approximately 0.05% of initially inoculated virions transmigrated via epithelium. More than 90% of internalized virions were sequestered in the endosomes of epithelial cells, including multivesicular bodies (MVBs) and vacuoles. Intraepithelial HIV-1 remained infectious for 9 days without viral release. Release of sequestered intraepithelial HIV-1 was induced by the calcium ionophore ionomycin and by cytochalasin D, which increase intracellular calcium and disrupt the cortical actin of epithelial cells, respectively. Cocultivation of epithelial cells containing HIV-1 with activated peripheral blood mononuclear cells and CD4+ T lymphocytes led to the disruption of epithelial cortical actin and spread of virus from epithelial cells to lymphocytes. Treatment of epithelial cells with proinflammatory cytokines tumor necrosis factor-alpha and interferon gamma also induced reorganization of cortical actin and release of virus. Inhibition of MVB formation by small interfering RNA (siRNA)-mediated silencing of its critical protein hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) expression reduced viral sequestration in epithelial cells and its transmission from epithelial cells to lymphocytes by ~60-70%. Furthermore, inhibition of vacuole formation of epithelial cells by siRNA-inactivated rabankyrin-5 expression also significantly reduced HIV-1 sequestration in epithelial cells and spread of virus from epithelial cells to lymphocytes. Interaction of the intercellular adhesion molecule-1 of epithelial cells with the function-associated antigen-1 of lymphocytes was important for inducing the release of sequestered HIV-1 from epithelial cells and facilitating cell-to-cell spread of virus from epithelial cells to lymphocytes. This mechanism may serve as a pathway of HIV-1 mucosal transmission.

Chemokine Levels in the Penile Coronal Sulcus Correlate with HIV-1 Acquisition and Are Reduced by Male Circumcision in Rakai, Uganda

Individual susceptibility to HIV is heterogeneous, but the biological mechanisms explaining differences are incompletely understood. We hypothesized that penile inflammation may increase HIV susceptibility in men by recruiting permissive CD4 T cells, and that male circumcision may decrease HIV susceptibility in part by reducing genital inflammation. We used multi-array technology to measure levels of seven cytokines in coronal sulcus (penile) swabs collected longitudinally from initially uncircumcised men enrolled in a randomized trial of circumcision in Rakai, Uganda. Coronal sulcus cytokine levels were compared between men who acquired HIV and controls who remained seronegative. Cytokines were also compared within men before and after circumcision, and correlated with CD4 T cells subsets in foreskin tissue. HIV acquisition was associated with detectable coronal sulcus Interleukin-8 (IL-8 aOR 2.26, 95%CI 1.04–6.40) and Monokine Induced by γ-interferon (MIG aOR 2.72, 95%CI 1.15–8.06) at the visit prior to seroconversion, and the odds of seroconversion increased with detection of multiple cytokines. Coronal sulcus chemokine levels were not correlated with those in the vagina of a man’s female sex partner. The detection of IL-8 in swabs was significantly reduced 6 months after circumcision (PRR 0.59, 95%CI 0.44–0.87), and continued to decline for at least two years (PRR 0.29, 95%CI 0.16–0.54). Finally, prepuce IL-8 correlated with increased HIV target cell density in foreskin tissues, including highly susceptible CD4 T cells subsets, as well as with tissue neutrophil density. Together, these data suggest that penile inflammation increases HIV susceptibility and is reduced by circumcision.

The per-contact risk of infection with HIV through sexual exposure is low and highly variable. Understanding the biological basis for this variability could help in the development of new methods to prevent infection. There is some evidence that penile inflammation, even in the absence of any clinical symptoms, may increase HIV-susceptibility by recruiting CD4 T cells, the immune cell type that is the principal target of HIV. We analyzed soluble inflammatory mediators in prepuce swabs collected longitudinally from initially HIV-negative men enrolled in a randomized controlled trial of adult circumcision. We found that these inflammatory mediators were elevated in men who went on to acquire HIV. We also found that higher levels of these mediators were associated with an increased density of HIV-susceptible target cells in the underlying foreskin tissue and that circumcision reduced their levels, which may help to explain why circumcision reduces HIV risk by 60% or more. Together, these data suggest that penile inflammation, in the absence of genital infections, increases HIV susceptibility and is reduced by adult male circumcision.

Does HIV Exploit the Inflammatory Milieu of the Male Genital Tract for Successful Infection?

In many parts of the World, medical male circumcision (MMC) is used as standard prevention of care against HIV infection. This is based on seminal reports made over 10 years ago that removal of the foreskin provides up to 60% protection against HIV infection in males and seems currently the best antiretroviral-free prevention strategy yet against the global epidemic. We explore the potential mechanisms by which MMC protects against HIV-1 acquisition and that one of the oldest, albeit re-invented, rituals of removing a foreskin underscores the exploitative nature of HIV on the anatomy and tissue of the uncircumcised penis. Furthermore, foreskin removal also reveals how males acquire HIV, and in reality, the underlying mechanisms of MMC are not known. We argue that the normal sequelae of inflammation in the male genital tract (MGT) for protection from sexually transmitted infections (STI)-induced pathology represents a perfect immune and microbial ecosystem for HIV acquisition. The accumulation of HIV-1 target cells in foreskin tissue and within the urethra in response to STIs, both during and after resolution of infection, suggests that acquisition of HIV-1, through sexual contact, makes use of the natural immune milieu of the MGT. Understanding immunity in the MGT, the movement of HIV-1 target cells to the urethra and foreskin tissue upon encounter with microbial signals would provide more insight into viral acquisition and lay the foundation for further prevention strategies in males that would be critical to curb the epidemic in all sexual partners at risk of infection. The global female-centric focus of HIV-1 transmission and acquisition research has tended to leave gaps in our knowledge of what determines HIV-1 acquisition in men and such understanding would provide a more balanced and complete view of viral acquisition.

Reversing Gut Damage in HIV Infection: Using Non-Human Primate Models to Instruct Clinical Research

Antiretroviral therapy (ART) has led to dramatic improvements in the lives of HIV-infected persons. However, residual immune activation, which persists despite ART, is associated with increased risk of non-AIDS morbidities. Accumulating evidence shows that disruption of the gut mucosal epithelium during SIV/HIV infections allows translocation of microbial products into the circulation, triggering immune activation. This disruption is due to immune, structural and microbial alterations. In this review, we highlighted the key findings of gut mucosa studies of SIV-infected macaques and HIV-infected humans that have revealed virus-induced changes of intestinal CD4, CD8 T cells, innate lymphoid cells, myeloid cells, and of the local cytokine/chemokine network in addition to epithelial injuries. We review the interplay between the host immune response and the intestinal microbiota, which also impacts disease progression. Collectively, these studies have instructed clinical research on early ART initiation, modifiers of microbiota composition, and recombinant cytokines for restoring gut barrier integrity.

Redundant prepuce increases the odds of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)

Some published evidence has revealed that the dendritic cells can interact with pathogens that exist in the inner foreskin. This information provides a new vision that pathogens could play a role through the redundant prepuce; numerous studies have failed to find pathogens in prostates of patients who had chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). However, no studies have reported an association between foreskin length and CP/CPPS. Hence, we conducted a retrospective case-control study of clinical data from 322 CP/CPPS patients (case group) and 341 nonCP/CPPS patients (control group). Demographic characteristics, lifestyle factors, and foreskin lengths were collected and analyzed. Multivariate logistic regression was adopted to calculate the odds of foreskin length for CP/CPPS. According to the multivariate logistic regression results, when the foreskin length covered up more than half of the glans penis, the odds for CP/CPPS were higher with an increased foreskin (odds ratio (OR): 1.66, 95% confidence interval (CI): 1.04–2.66). In comparison, when the glans penis was completely covered by the foreskin, the OR value increased to 1.86 (95% CI, 1.2–2.88). The study results showed an association between foreskin length and the odds of CP/CPPS. When the foreskin length covered up more than half of the glans penis, there were greater odds for CP/CPPS. This possible mechanism might result from interaction between pathogens and DCs in the inner foreskin, consequently activating T-cells to mediate allergic inflammation in the prostate and producing the autoimmunizations causing CP/CPPS.

Herpes simplex virus type 2-infected dendritic cells produce TNF-α, which enhances CCR5 expression and stimulates HIV production from adjacent infected cells

Prior HSV-2 infection enhances the acquisition of HIV-1 >3-fold. In genital herpes lesions, the superficial layers of stratified squamous epithelium are disrupted, allowing easier access of HIV-1 to Langerhans cells (LC) in the epidermis and perhaps even dendritic cells (DCs) in the outer dermis, as well as to lesion infiltrating activated T lymphocytes and macrophages. Therefore, we examined the effects of coinfection with HIV-1 and HSV-2 on monocyte-derived DCs (MDDC). With simultaneous coinfection, HSV-2 significantly stimulated HIV-1 DNA production 5-fold compared with HIV-1 infection alone. Because <1% of cells were dually infected, this was a field effect. Virus-stripped supernatants from HSV-2-infected MDDCs were shown to enhance HIV-1 infection, as measured by HIV-1-DNA and p24 Ag in MDDCs. Furthermore these supernatants markedly stimulated CCR5 expression on both MDDCs and LCs. TNF-α was by far the most prominent cytokine in the supernatant and also within HSV-2-infected MDDCs. HSV-2 infection of isolated immature epidermal LCs, but not keratinocytes, also produced TNF-α (and low levels of IFN-β). Neutralizing Ab to TNF-α and its receptor, TNF-R1, on MDDCs markedly inhibited the CCR5-stimulating effect of the supernatant. Therefore, these results suggest that HSV-2 infection of DCs in the skin during primary or recurrent genital herpes may enhance HIV-1 infection of adjacent DCs, thus contributing to acquisition of HIV-1 through herpetic lesions.