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Nelson SG, Liu CM. Penile microbiome: decoding its impact on HIV risk. Curr Opin HIV AIDS 2024:01222929-990000000-00098. [PMID: 38935058 DOI: 10.1097/coh.0000000000000865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
PURPOSE OF REVIEW The penile microbiome has been linked to local inflammation and increased risk for sexually transmitted infections, including HIV. This review explores recent studies of this emerging area of HIV research. RECENT FINDINGS The male urogenital tract supports multiple distinct niches, where their associated microbiome are shaped by abiotic (e.g., oxygen, moisture) and biotic (e.g., host immunity) environmental factors and host behaviors, particularly sexual activity. In addition, male circumcision is a significant drivers of male genital microbiome in both children and adults. Recent sexual partner studies provide new insight into the exchange of genital bacteria and concurrent local immune changes that may impact HIV risk. SUMMARY The male genital microbiome is shaped by the local microenvironment and host behaviors including sexual activity. Improving our understanding of the connection between the male genital microbiome, local inflammation, and HIV susceptibility, as well as how pro-inflammatory genital bacteria are transmitted between sexual partners may inform new strategies to prevent HIV transmission.
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Affiliation(s)
- Sydney G Nelson
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA
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2
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Armstrong E, Kaul R, Cohen CR. Optimizing the vaginal microbiome as a potential strategy to reduce heterosexual HIV transmission. J Intern Med 2023; 293:433-444. [PMID: 36544257 DOI: 10.1111/joim.13600] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bacterial vaginosis (BV) is a proinflammatory genital condition characterized by high vaginal bacterial diversity and a paucity of Lactobacillus species. BV has been linked to an elevated risk of HIV acquisition among HIV-negative women and of forward HIV transmission to male sex partners among women living with HIV (adjusted hazard ratios of 1.69 and 3.17, respectively), potentially by eliciting genital inflammation in women with BV and their male sex partners. BV is also highly prevalent among women in sub-Saharan Africa, suggesting that BV treatment may have potential as an HIV prevention strategy. BV is typically treated with antibiotics but recurrence rates are high, possibly because treatment does not directly promote Lactobacillus growth. More recently, BV treatment strategies incorporating live biotherapeutic lactobacilli have led to sustained optimization of the vaginal microbiome and a decrease in inflammatory biomarkers previously associated with HIV susceptibility. Future studies are urgently needed to evaluate BV treatment strategies that can optimize the vaginal microbiome in the long term through colonization with H2 O2 -producing vaginal lactobacilli and to assess whether vaginal microbiota optimization is able to reduce the risk of HIV transmission.
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Affiliation(s)
- Eric Armstrong
- Department of Medicine, University of Toronto, Toronto, Canada
| | - Rupert Kaul
- Department of Medicine, University of Toronto, Toronto, Canada.,Department of Medicine, University Health Network, Toronto, Canada
| | - Craig R Cohen
- Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Francisco, San Francisco, USA
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Prodger JL, Galiwango RM, Tobian AAR, Park D, Liu CM, Kaul R. How Does Voluntary Medical Male Circumcision Reduce HIV Risk? Curr HIV/AIDS Rep 2022; 19:484-490. [PMID: 36308579 PMCID: PMC9617235 DOI: 10.1007/s11904-022-00634-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2022] [Indexed: 01/31/2023]
Abstract
PURPOSE OF REVIEW Voluntary medical male circumcision (VMMC) is a surgical procedure that reduces HIV acquisition risk by almost two-thirds. However, global implementation is lagging, in part due to VMMC hesitancy. A better understanding of the mechanism(s) by which this procedure protects against HIV may increase acceptance of VMMC as an HIV risk reduction approach among health care providers and their clients. RECENT FINDINGS HIV acquisition in the uncircumcised penis occurs preferentially across the inner foreskin tissues, due to increased susceptibility that is linked to elevated inflammatory cytokine levels in the sub-preputial space and an increased tissue density of HIV-susceptible CD4 + T cells. Inflammation can be caused by sexually transmitted infections, but is more commonly induced by specific anaerobic components of the penile microbiome. Circumcision protects by both directly removing the susceptible tissues of the inner foreskin, and by inducing a less inflammatory residual penile microbiome. VMMC reduces HIV susceptibility by removing susceptible penile tissues, and also through impacts on the penile immune and microbial milieu. Understanding these mechanisms may not only increase VMMC acceptability and reinvigorate global VMMC programs, but may also lead to non-surgical HIV prevention approaches focused on penile immunology and/or microbiota.
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Affiliation(s)
- Jessica L Prodger
- Departments of Microbiology and Immunology and Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 5C1, Canada
| | | | - Aaron A R Tobian
- Department of Pathology, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Daniel Park
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, 20052, USA
| | - Cindy M Liu
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, 20052, USA
| | - Rupert Kaul
- Departments of Medicine and Immunology, University of Toronto, Medical Sciences Building Rm. 6356, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
- University Health Network, Toronto, ON, Canada.
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Cepeda-Emiliani A, Gándara-Cortés M, Otero-Alén M, García H, Suárez-Quintanilla J, García-Caballero T, Gallego R, García-Caballero L. Immunohistological study of the density and distribution of human penile neural tissue: gradient hypothesis. Int J Impot Res 2022; 35:286-305. [PMID: 35501394 DOI: 10.1038/s41443-022-00561-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 03/03/2022] [Accepted: 03/08/2022] [Indexed: 01/12/2023]
Abstract
Immunohistological patterns of density and distribution of neural tissue in the human penis, including the prepuce, are not fully characterized, and effects of circumcision (partial or total removal of the penile prepuce) on penile sexual sensation are controversial. This study analyzed extra- and intracavernosal innervation patterns on the main penile axes using formalin-fixed, paraffin-embedded human adult and fetal penile tissues, single- and double-staining immunohistochemistry and a variety of neural and non-neural markers, with a special emphasis on the prepuce and potential sexual effects of circumcision. Immunohistochemical profiles of neural structures were determined and the most detailed immunohistological characterizations to date of preputial nerve supply are provided. The penile prepuce has a highly organized, dense, afferent innervation pattern that is manifest early in fetal development. Autonomically, it receives noradrenergic sympathetic and nitrergic parasympathetic innervation. Cholinergic nerves are also present. We observed cutaneous and subcutaneous neural density distribution biases across our specimens towards the ventral prepuce, including a region corresponding in the adult anatomical position (penis erect) to the distal third of the ventral penile aspect. We also describe a concept of innervation gradients across the longitudinal and transverse penile axes. Results are discussed in relation to the specialized literature. An argument is made that neuroanatomic substrates underlying unusual permanent penile sensory disturbances post-circumcision are related to heightened neural levels in the distal third of the ventral penile aspect, which could potentially be compromised by deep incisions during circumcision.
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Affiliation(s)
- Alfonso Cepeda-Emiliani
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
| | - Marina Gándara-Cortés
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain.,Department of Pathology, University Clinical Hospital, Santiago de Compostela, Spain
| | - María Otero-Alén
- Health Research Institute of Santiago (IDIS), Santiago de Compostela, Spain
| | - Heidy García
- National Institute of Legal Medicine and Forensic Sciences of Colombia, Barranquilla, Colombia
| | - Juan Suárez-Quintanilla
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Tomás García-Caballero
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain.,Department of Pathology, University Clinical Hospital, Santiago de Compostela, Spain
| | - Rosalía Gallego
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Lucía García-Caballero
- Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain
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The Role of Tissue Resident Memory CD4 T Cells in Herpes Simplex Viral and HIV Infection. Viruses 2021; 13:v13030359. [PMID: 33668777 PMCID: PMC7996247 DOI: 10.3390/v13030359] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
Tissue-resident memory T cells (TRM) were first described in 2009. While initially the major focus was on CD8+ TRM, there has recently been increased interest in defining the phenotype and the role of CD4+ TRM in diseases. Circulating CD4+ T cells seed CD4+ TRM, but there also appears to be an equilibrium between CD4+ TRM and blood CD4+ T cells. CD4+ TRM are more mobile than CD8+ TRM, usually localized deeper within the dermis/lamina propria and yet may exhibit synergy with CD8+ TRM in disease control. This has been demonstrated in herpes simplex infections in mice. In human recurrent herpes infections, both CD4+ and CD8+ TRM persisting between lesions may control asymptomatic shedding through interferon-gamma secretion, although this has been more clearly shown for CD8+ T cells. The exact role of the CD4+/CD8+ TRM axis in the trigeminal ganglia and/or cornea in controlling recurrent herpetic keratitis is unknown. In HIV, CD4+ TRM have now been shown to be a major target for productive and latent infection in the cervix. In HSV and HIV co-infections, CD4+ TRM persisting in the dermis support HIV replication. Further understanding of the role of CD4+ TRM and their induction by vaccines may help control sexual transmission by both viruses.
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Yegorov S, Joag V, Galiwango RM, Good SV, Okech B, Kaul R. Impact of Endemic Infections on HIV Susceptibility in Sub-Saharan Africa. TROPICAL DISEASES TRAVEL MEDICINE AND VACCINES 2019; 5:22. [PMID: 31798936 PMCID: PMC6884859 DOI: 10.1186/s40794-019-0097-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Human immunodeficiency virus (HIV) remains a leading cause of global morbidity with the highest burden in Sub-Saharan Africa (SSA). For reasons that are incompletely understood, the likelihood of HIV transmission is several fold higher in SSA than in higher income countries, and most of these infections are acquired by young women. Residents of SSA are also exposed to a variety of endemic infections, such as malaria and various helminthiases that could influence mucosal and systemic immunology. Since these immune parameters are important determinants of HIV acquisition and progression, this review explores the possible effects of endemic infections on HIV susceptibility and summarizes current knowledge of the epidemiology and underlying immunological mechanisms by which endemic infections could impact HIV acquisition. A better understanding of the interaction between endemic infections and HIV may enhance HIV prevention programs in SSA.
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Affiliation(s)
- Sergey Yegorov
- 1Departments of Immunology and Medicine, University of Toronto, Toronto, Canada.,2Department of Pedagogical Mathematics and Natural Science, Faculty of Education and Humanities, Suleyman Demirel University, Almaty, Kazakhstan
| | - Vineet Joag
- 3Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN USA
| | - Ronald M Galiwango
- 1Departments of Immunology and Medicine, University of Toronto, Toronto, Canada
| | - Sara V Good
- 4Genetics & Genome Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON Canada.,5Community Health Sciences, University of Manitoba, Winnipeg, MB Canada
| | | | - Rupert Kaul
- 1Departments of Immunology and Medicine, University of Toronto, Toronto, Canada.,7Department of Medicine, University Health Network, Toronto, Canada
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Galiwango RM, Bagaya B, Mpendo J, Joag V, Okech B, Nanvubya A, Ssetaala A, Muwanga M, Kaul R. Protocol for a randomized clinical trial exploring the effect of antimicrobial agents on the penile microbiota, immunology and HIV susceptibility of Ugandan men. Trials 2019; 20:443. [PMID: 31324206 PMCID: PMC6642556 DOI: 10.1186/s13063-019-3545-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 06/29/2019] [Indexed: 04/16/2023] Open
Abstract
Background The foreskin is the main site of HIV acquisition in a heterosexual uncircumcised man, but many men in endemic countries are reluctant to undergo penile circumcision (PC). Observational studies suggest that proinflammatory anaerobic bacteria are enriched on the uncircumcised penis, where they may enhance HIV susceptibility through increased foreskin inflammatory cytokines and the recruitment of HIV-susceptible CD4+ target cells. This trial will examine the impact of systemic and topical antimicrobials on ex vivo foreskin HIV susceptibility. Methods/design This randomized, open-label clinical trial will randomize 125 HIV-negative Ugandan men requesting voluntary PC to one of five arms (n = 25 each). The control group will receive immediate PC, while the four intervention groups will defer PC for 1 month and be provided in the interim with either oral tinidazole, penile topical metronidazole, topical clindamycin, or topical hydrogen peroxide. The impact of these interventions on HIV entry into foreskin-derived CD4+ T cells will be quantified ex vivo at the time of PC using a clade A, R5 tropic HIV pseudovirus assay (primary endpoint); secondary endpoints include the impact of antimicrobials on immune parameters and the microbiota of the participant’s penis and of the vagina of their female partner (if applicable), assessed by multiplex enzyme-linked immunosorbent assay and 16S rRNA sequencing. Discussion There is a critical need to develop acceptable, simple, and effective means of HIV prevention in men unwilling to undergo PC. This trial will provide insight into the causative role of the foreskin microbiota on HIV susceptibility, and the impact of simple microbiota-focused clinical interventions. This may pave the way for future clinical trials using low-cost, nonsurgical intervention(s) to reduce HIV risk in uncircumcised heterosexual men. Trial registration ClinicalTrials.gov, NCT03412071. Retrospectively registered on 26 January 2018. Electronic supplementary material The online version of this article (10.1186/s13063-019-3545-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ronald M Galiwango
- Department of Immunology, University of Toronto, St. George Campus Medical Sciences Building #6356 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Bernard Bagaya
- HIV Vaccine Program, Uganda Virus Research Institute-International AIDS Vaccine Initiative, Entebbe, Uganda.,Department of Microbiology, Makerere University College of Health Sciences, Kampala, Uganda
| | - Juliet Mpendo
- HIV Vaccine Program, Uganda Virus Research Institute-International AIDS Vaccine Initiative, Entebbe, Uganda
| | - Vineet Joag
- Department of Immunology, University of Toronto, St. George Campus Medical Sciences Building #6356 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Brenda Okech
- HIV Vaccine Program, Uganda Virus Research Institute-International AIDS Vaccine Initiative, Entebbe, Uganda
| | - Annet Nanvubya
- HIV Vaccine Program, Uganda Virus Research Institute-International AIDS Vaccine Initiative, Entebbe, Uganda
| | - Ali Ssetaala
- HIV Vaccine Program, Uganda Virus Research Institute-International AIDS Vaccine Initiative, Entebbe, Uganda
| | | | - Rupert Kaul
- Department of Immunology, University of Toronto, St. George Campus Medical Sciences Building #6356 1 King's College Circle, Toronto, ON, M5S 1A8, Canada. .,Department of Medicine, University of Toronto, Toronto, ON, Canada. .,Department of Medicine, University Health Network, Toronto, ON, Canada.
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