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Almomani O, Nnamutete J, Shao Z, Biribawa VM, Ssemunywa H, Namuniina A, Okech B, Ulanova S, Zuanazzi D, Liu CM, Tobian AAR, Galiwango RM, Kaul R, Prodger JL. Effect of cryopreservation on CD4+ T cell subsets in foreskin tissue. PLoS One 2024; 19:e0297884. [PMID: 38427640 PMCID: PMC10906856 DOI: 10.1371/journal.pone.0297884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/03/2024] [Indexed: 03/03/2024] Open
Abstract
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.
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Affiliation(s)
- Omar Almomani
- Department of Microbiology and Immunology, Western University, London, Canada
| | | | - Zhongtian Shao
- Department of Microbiology and Immunology, Western University, London, Canada
| | | | | | | | - Brenda Okech
- UVRI-IAVI HIV Vaccine Program Limited, Entebbe, Uganda
| | - Sofya Ulanova
- Department of Microbiology and Immunology, Western University, London, Canada
| | - David Zuanazzi
- Department of Microbiology and Immunology, Western University, London, Canada
| | - Cindy M. Liu
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, United States of America
| | - Aaron A. R. Tobian
- Department of Pathology, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | | | - Rupert Kaul
- Departments of Medicine and Immunology, University of Toronto, Toronto, Canada
- University Health Network, Toronto, Canada
| | - Jessica L. Prodger
- Department of Microbiology and Immunology, Western University, London, Canada
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2
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Day E, Galiwango RM, Park D, Huibner S, Aziz M, Anok A, Nnamutete J, Isabirye Y, Wasswa JB, Male D, Kigozi G, Tobian AA, Prodger JL, Liu CM, Kaul R. Insertive vaginal sex is associated with altered penile immunology and enrichment of Gardnerella vaginalis in uncircumcised Ugandan men. Am J Reprod Immunol 2024; 91:e13801. [PMID: 38282609 PMCID: PMC10825315 DOI: 10.1111/aji.13801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 07/13/2023] [Accepted: 11/17/2023] [Indexed: 01/30/2024] Open
Abstract
PROBLEM HIV susceptibility is linked to the penile immune milieu (particularly IL-8 levels) and microbiome. The effects of insertive vaginal sex itself on penile immunology and microbiota are not well described. METHOD OF STUDY We compared the immune milieu and microbiology of the coronal sulcus (CS) and distal urethra in 47 uncircumcised Ugandan men reporting ever (n = 42) or never (n = 5) having had vaginal intercourse. Soluble immune factors were assayed by multiplex ELISA, and penile bacteria abundance by 16S rRNA qPCR and sequencing. Co-primary endpoints were penile levels of IL-8 and soluble E-cadherin. RESULTS Independent of classical STIs, men reporting prior vaginal sex demonstrated elevated IL-8 levels in both the coronal sulcus (1.78 vs. 0.81 log10 pg/mL, p = .021) and urethra (2.93 vs. 2.30 log10 pg/mL; p = .003), with a strong inverse relationship between urethral IL-8 levels and the time from last vaginal sex (r = -0.436; p = .004). Vaginal sex was also associated with elevated penile IL-1α/β and soluble E-cadherin (sEcad), a marker of epithelial disruption. Gardnerella vaginalis (Gv) was only present in the penile microbiome of men reporting prior vaginal sex, and urethral Gv absolute abundance was strongly associated with urethral inflammation (r = 0.556; p < .001); corynebacteria were enriched in the CS of men reporting no prior vaginal sex and were associated with reduced CS inflammation. CONCLUSIONS Sexual intercourse was associated with sustained changes in penile immunology, potentially mediated through microbial alterations, in particular the urethral abundance of G. vaginalis. Future studies should further characterize the effects of sexual debut on penile bacteria and immunology.
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Affiliation(s)
- Erin Day
- Department of Microbiology and Immunology, Western University, Ontario, Canada
| | - Ronald M. Galiwango
- Departments of Immunology and Medicine, University of Toronto, Ontario, Canada
- Rakai Health Sciences Program, Kalisizo, Uganda
| | - Daniel Park
- George Washington Milken Institute School of Public Health, Washington DC, USA
| | - Sanja Huibner
- Departments of Immunology and Medicine, University of Toronto, Ontario, Canada
| | - Maliha Aziz
- George Washington Milken Institute School of Public Health, Washington DC, USA
| | - Aggrey Anok
- Rakai Health Sciences Program, Kalisizo, Uganda
| | | | | | | | - Deo Male
- Rakai Health Sciences Program, Kalisizo, Uganda
| | | | - Aaron A.R. Tobian
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jessica L. Prodger
- Department of Microbiology and Immunology, Western University, Ontario, Canada
| | - Cindy M. Liu
- George Washington Milken Institute School of Public Health, Washington DC, USA
| | - Rupert Kaul
- Departments of Immunology and Medicine, University of Toronto, Ontario, Canada
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3
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Maust BS, Petkov S, Herrera C, Feng C, Brown BP, Lebina L, Opoka D, Ssemata A, Pillay N, Serwanga J, Seatlholo P, Namubiru P, Odoch G, Mugaba S, Seiphetlo T, Gray CM, Kaleebu P, Webb EL, Martinson N, Chiodi F, Fox J, Jaspan HB. Bacterial microbiome and host inflammatory gene expression in foreskin tissue. Heliyon 2023; 9:e22145. [PMID: 38053902 PMCID: PMC10694185 DOI: 10.1016/j.heliyon.2023.e22145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 10/20/2023] [Accepted: 11/05/2023] [Indexed: 12/07/2023] Open
Abstract
The penile epithelial microbiome remains underexplored. We sequenced human RNA and a segment of the bacterial 16S rRNA gene from the foreskin tissue of 144 adolescents from South Africa and Uganda collected during penile circumcision after receipt of 1-2 doses of placebo, emtricitabine + tenofovir disoproxil fumarate, or emtricitabine + tenofovir alafenamide to investigate the microbiome of foreskin tissue and its potential changes with antiretroviral use. We identified a large number of anaerobic species, including Corynebacterium acnes, which was detected more frequently in participants from South Africa than Uganda. Bacterial populations did not differ by treatment received, and no differentially abundant taxa were identified between placebo versus active drug recipients. The relative abundance of specific bacterial taxa was negatively correlated with expression of genes downstream of the innate immune response to bacteria and regulation of inflammation. Our results show no difference in the tissue microbiome of the foreskin with short-course antiretroviral use but that bacterial taxa were largely inversely correlated with inflammatory gene expression, consistent with commensal colonization.
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Affiliation(s)
- Brandon S. Maust
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, 98109, USA
- Division of Infectious Disease, Dept of Pediatrics, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Stefan Petkov
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
| | - Carolina Herrera
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W2 1PG, UK
| | - Colin Feng
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, 98109, USA
| | - Bryan P. Brown
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, 98109, USA
- Division of Infectious Disease, Dept of Pediatrics, University of Washington School of Medicine, Seattle, WA, 98195, USA
| | - Limakatso Lebina
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, 2000, South Africa
| | - Daniel Opoka
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Andrew Ssemata
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Natasha Pillay
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, 2000, South Africa
| | - Jennifer Serwanga
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Portia Seatlholo
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, 2000, South Africa
| | - Patricia Namubiru
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Geoffrey Odoch
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Susan Mugaba
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Thabiso Seiphetlo
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
| | - Clive M. Gray
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Stellenbosch, 7602, South Africa
| | - Pontiano Kaleebu
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
| | - Emily L. Webb
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Neil Martinson
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, 2000, South Africa
| | - Francesca Chiodi
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
| | - Julie Fox
- Faculty of Life Sciences & Medicine, School of Immunology & Microbial Sciences, Kings College, London, WC2R 2LS, UK
| | - Heather B. Jaspan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, 98109, USA
- Division of Infectious Disease, Dept of Pediatrics, University of Washington School of Medicine, Seattle, WA, 98195, USA
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
| | - CHAPS team
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, 98109, USA
- Division of Infectious Disease, Dept of Pediatrics, University of Washington School of Medicine, Seattle, WA, 98195, USA
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W2 1PG, UK
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, 2000, South Africa
- Medical Research Council, Uganda Virus Research Institute, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Stellenbosch, 7602, South Africa
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Faculty of Life Sciences & Medicine, School of Immunology & Microbial Sciences, Kings College, London, WC2R 2LS, UK
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4
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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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5
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Mishra K, Isali I, Sindhani M, Prunty M, Bell S, Mahran A, Damiani G, Ghannoum M, Retuerto M, Kutikov A, Ross J, Woo LL, Abbosh PH, Bukavina L. Characterization of Changes in Penile Microbiome Following Pediatric Circumcision. Eur Urol Focus 2022:S2405-4569(22)00290-5. [PMID: 36566099 DOI: 10.1016/j.euf.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/25/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022]
Abstract
BACKGROUND While microbiome and host regulation contribute independently to many disease states, it is unclear how circumcision in pediatric population influences subsequent changes in penile microbiome. OBJECTIVE Our study aims to analyze jointly paired taxonomic profiles and assess pathways implicated in inflammation, barrier protection, and energy metabolism. DESIGN, SETTING, AND PARTICIPANTS We analyzed 11 paired samples, periurethral collection, before and after circumcision, to generate microbiome and mycobiome profiling. Sample preparation of 16S ribosomal RNA and internal transcribed spacer sequencing was adapted from the methods developed by the National Institutes of Health Human Microbiome Project. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS We obtained the predictive functional attributes of the microbial communities between samples using Silva-Tax4Fun and the Greengenes-Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) approach. The predictive functioning of the microbial communities was determined by linearly combining the normalized taxonomic abundances into the precomputed association matrix of Kyoto Encyclopedia of Genes and Genomes orthology reference profiles. RESULTS AND LIMITATIONS Several notable microbiome and mycobiome compositional differences were observed between pre- and postcircumcision patients. Pairwise comparisons across taxa revealed a significant decrease (p < 0.05, false discovery rate corrected) of microbiome organisms (Clostridiales, Bacteroidales, and Campylobacterales) and mycobiome (Saccharomycetales and Pleosporales) following circumcision. A total of 14 pathways were found to differ in abundance between the pre- and postcircumcision groups (p < 0.005, false discovery rate <0.1 and linear discriminant analysis score >3; five enriched and nine depleted). The pathways reduced after circumcision were mostly involved with amino acid and glucose metabolism, while pathways prior to circumcision were enriched in genetic information processing and transcription processes. As expected, enrichment in methyl-accepting chemotaxis protein, an integral membrane protein involved in directed motility of microbes to chemical cues and environment, occurred prior to circumcision, while the filamentous hemagglutinin pathway (a strong immunogenic protein) was depleted after circumcision CONCLUSIONS: Our results offer greater insight into the host-microbiota relationship of penile circumcision and may serve to lay the groundwork for future studies focused on drivers of inflammation, infection, and oncogenesis. PATIENT SUMMARY Our study showed a significant reduction in bacteria and fungi after circumcision, particularly anaerobic bacteria, which are known to be potential inducers of inflammation and cancer. This is the first study of its kind showing the changes in microbiome after circumcision, and some of the changes that occur in healthy infants after circumcision that may explain the differences in cancer and inflammatory disorders in adulthood.
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Affiliation(s)
- Kirtishri Mishra
- Department of Urology, New York University, Langone Medical Center, New York, NY, USA; Department of Urology, University Hospitals, Cleveland Medical Center, Cleveland, OH, USA
| | - Ilaha Isali
- Department of Urology, University Hospitals, Cleveland Medical Center, Cleveland, OH, USA
| | | | - Megan Prunty
- Department of Urology, University Hospitals, Cleveland Medical Center, Cleveland, OH, USA
| | | | - Amr Mahran
- Department of Urology, University of Tennessee, Knoxville, TN, USA; Department of Urology, Assiut University, Assiut, Egypt
| | - Giovanni Damiani
- Department of Dermatology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA; Department of Biomedical, Surgical, and Dental Sciences, University of Milan, Milan, Italy
| | - Mahmoud Ghannoum
- Department of Dermatology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA; Case Western Reserve School of Medicine, Center for Medical Mycology, Cleveland, OH, USA
| | - Mauricio Retuerto
- Case Western Reserve School of Medicine, Center for Medical Mycology, Cleveland, OH, USA
| | | | - Jonathan Ross
- Department of Urology, Rush University, Chicago, IL, USA
| | - Lynn L Woo
- Einstein Medical Center, Department of Urology, Philadelphia, PA, USA
| | - Philip H Abbosh
- Fox Chase Cancer Center, Philadelphia, PA, USA; Department of Urology, Rainbow Babies and Children's Hospital, Cleveland, OH, USA
| | - Laura Bukavina
- Department of Urology, University Hospitals, Cleveland Medical Center, Cleveland, OH, USA; Fox Chase Cancer Center, Philadelphia, PA, USA.
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6
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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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7
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Kaul R, Liu CM, Park DE, Galiwango RM, Tobian AAR, Prodger JL. The Penis, the Vagina and HIV Risk: Key Differences (Aside from the Obvious). Viruses 2022; 14:v14061164. [PMID: 35746636 PMCID: PMC9227947 DOI: 10.3390/v14061164] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 12/14/2022] Open
Abstract
Globally, most Human Immunodeficiency Virus type 1 (HIV) transmission occurs through vaginal–penile sex (heterosexual transmission). The local immune environment at the site of HIV exposure is an important determinant of whether exposure during sex will lead to productive infection, and the vaginal and penile immune milieus are each critically shaped by the local microbiome. However, there are key differences in the microbial drivers of inflammation and immune quiescence at these tissue sites. In both, a high abundance of anaerobic taxa (e.g., Prevotella) is associated with an increased local density of HIV target cells and an increased risk of acquiring HIV through sex. However, the taxa that have been associated to date with increased risk in the vagina and penis are not identical. Just as importantly, the microbiota associated with comparatively less inflammation and HIV risk—i.e., the optimal microbiota—are very different at the two sites. In the vagina, Lactobacillus spp. are immunoregulatory and may protect against HIV acquisition, whereas on the penis, “skin type” flora such as Corynebacterium are associated with reduced inflammation. Compared to its vaginal counterpart, much less is known about the dynamics of the penile microbiome, the ability of clinical interventions to alter the penile microbiome, or the impact of natural/induced microbiome alterations on penile immunology and HIV risk.
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Affiliation(s)
- Rupert Kaul
- Departments of Medicine and Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada;
- Department of Medicine, University Health Network, Toronto, ON M5S 1A8, Canada
| | - Cindy M. Liu
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC 20052, USA; (C.M.L.); (D.E.P.)
| | - Daniel E. Park
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC 20052, USA; (C.M.L.); (D.E.P.)
| | | | - Aaron A. R. Tobian
- Department of Pathology, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA;
| | - Jessica L. Prodger
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
- Correspondence:
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