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Neto FTL, Viana MC, Cariati F, Conforti A, Alviggi C, Esteves SC. Effect of environmental factors on seminal microbiome and impact on sperm quality. Front Endocrinol (Lausanne) 2024; 15:1348186. [PMID: 38455659 PMCID: PMC10918436 DOI: 10.3389/fendo.2024.1348186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 01/29/2024] [Indexed: 03/09/2024] Open
Abstract
Objective This review provides a comprehensive overview of the existing research on the seminal microbiome and its association with male infertility, while also highlighting areas that warrant further investigation. Methods A narrative review was conducted, encompassing all relevant studies published between 1980-2023 on the male reproductive tract microbiome in humans. This review considered studies utilizing culture-based, polymerase chain reaction (PCR)-based, and next-generation sequencing (NGS)-based methodologies to analyze the microbiome. Data extraction encompassed sample types (semen or testicular tissue), study designs, participant characteristics, employed techniques, and critical findings. Results We included 37 studies comprising 9,310 participants. Among these, 16 studies used culture-based methods, 16 utilized NGS, and five employed a combination of methods for microorganism identification. Notably, none of the studies assessed fungi or viruses. All NGS-based studies identified the presence of bacteria in all semen samples. Two notable characteristics of the seminal microbiome were observed: substantial variability in species composition among individuals and the formation of microbial communities with a dominant species. Studies examining the testicular microbiome revealed that the testicular compartment is not sterile. Interestingly, sexually active couples shared 56% of predominant genera, and among couples with positive cultures in both partners, 61% of them shared at least one genital pathogen. In couples with infertility of known causes, there was an overlap in bacterial composition between the seminal and vaginal microbiomes, featuring an increased prevalence of Staphylococcus and Streptococcus genera. Furthermore, the seminal microbiome had discernible effects on reproductive outcomes. However, bacteria in IVF culture media did not seem to impact pregnancy rates. Conclusion Existing literature underscores that various genera of bacteria colonize the male reproductive tract. These organisms do not exist independently; instead, they play a pivotal role in regulating functions and maintaining hemostasis. Future research should prioritize longitudinal and prospective studies and investigations into the influence of infertility causes and commonly prescribed medication to enhance our understanding of the seminal microbiota's role in reproductive health.
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Affiliation(s)
| | - Marina C. Viana
- ANDROFERT, Andrology and Human Reproduction Clinic, Campinas, Brazil
| | - Federica Cariati
- Department of Public Health, University of Naples Federico II, Napoli, Italy
| | - Alessandro Conforti
- Department of Neuroscience, Reproductive Science and Odontostomatology, University of Naples, Federico II, Naples, Italy
| | - Carlo Alviggi
- Department of Public Health, University of Naples Federico II, Napoli, Italy
| | - Sandro C. Esteves
- ANDROFERT, Andrology and Human Reproduction Clinic, Campinas, Brazil
- Department of Surgery (Division of Urology), University of Campinas (UNICAMP), Campinas, Brazil
- Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
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Salas-Espejo E, Terrón-Camero LC, Ruiz JL, Molina NM, Andrés-León E. Exploring the Microbiome in Human Reproductive Tract: High-Throughput Methods for the Taxonomic Characterization of Microorganisms. Semin Reprod Med 2023; 41:125-143. [PMID: 38320576 DOI: 10.1055/s-0044-1779025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Microorganisms are important due to their widespread presence and multifaceted roles across various domains of life, ecology, and industries. In humans, they underlie the proper functioning of multiple systems crucial to well-being, including immunological and metabolic functions. Emerging research addressing the presence and roles of microorganisms within human reproduction is increasingly relevant. Studies implementing new methodologies (e.g., to investigate vaginal, uterine, and semen microenvironments) can now provide relevant insights into fertility, reproductive health, or pregnancy outcomes. In that sense, cutting-edge sequencing techniques, as well as others such as meta-metabolomics, culturomics, and meta-proteomics, are becoming more popular and accessible worldwide, allowing the characterization of microbiomes at unprecedented resolution. However, they frequently involve rather complex laboratory protocols and bioinformatics analyses, for which researchers may lack the required expertise. A suitable pipeline would successfully enable both taxonomic classification and functional profiling of the microbiome, providing easy-to-understand biological interpretations. However, the selection of an appropriate methodology would be crucial, as it directly impacts the reproducibility, accuracy, and quality of the results and observations. This review focuses on the different current microbiome-related techniques in the context of human reproduction, encompassing niches like vagina, endometrium, and seminal fluid. The most standard and reliable methods are 16S rRNA gene sequencing, metagenomics, and meta-transcriptomics, together with complementary approaches including meta-proteomics, meta-metabolomics, and culturomics. Finally, we also offer case examples and general recommendations about the most appropriate methods and workflows and discuss strengths and shortcomings for each technique.
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Affiliation(s)
- Eduardo Salas-Espejo
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada, Spain
| | - Laura C Terrón-Camero
- Bioinformatics Unit, Institute of Parasitology and Biomedicine "López-Neyra" (IPBLN), CSIC, Granada, Spain
| | - José L Ruiz
- Bioinformatics Unit, Institute of Parasitology and Biomedicine "López-Neyra" (IPBLN), CSIC, Granada, Spain
| | - Nerea M Molina
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada, Spain
| | - Eduardo Andrés-León
- Bioinformatics Unit, Institute of Parasitology and Biomedicine "López-Neyra" (IPBLN), CSIC, Granada, Spain
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Alqawasmeh O, Fok E, Yim H, Li T, Chung J, Chan D. The microbiome and male infertility: looking into the past to move forward. HUM FERTIL 2023; 26:450-462. [PMID: 36039770 DOI: 10.1080/14647273.2022.2098540] [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: 11/12/2021] [Accepted: 03/12/2022] [Indexed: 11/04/2022]
Abstract
The human body harbours trillions of microbes, and their influence on human health has been explored in many parts of the human body, including the male reproductive system. From routine culturing to polymerise chain reaction (PCR) and high throughput DNA sequencing, several studies have identified bacteria in the male reproductive system. In this review, we discuss the past and current literature surrounding the testicular and semen microbiome in correlation with male infertility. We further highlight the potential benefits of probiotics as an alternative therapeutic option for male infertility. Although not conclusive, emerging data are indicating potential implications of certain bacterial members on male fertility. There is a general agreement on the negative impact of some pathogenic bacterial species on semen parameters, including sperm counts, motility, morphology, and DNA integrity. On the other hand, Lactobacillus, known as a human-friendly bacteria, has shown protective effects on semen parameters, which makes it a potentially good probiotic. In order to confirm the findings of previous studies, more clinical studies with larger sample sizes and the right controls are needed.
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Affiliation(s)
- Odai Alqawasmeh
- Assisted Reproductive Technology, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ellis Fok
- Department of Biomedical Science, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China
| | - Howard Yim
- Microbiome Research Centre, Department of Medicine, St George & Sutherland Clinical School, Faculty of Medicine, UNSW, Sydney, Australia
| | - Tin Li
- Assisted Reproductive Technology, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jacqueline Chung
- Assisted Reproductive Technology, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - David Chan
- Assisted Reproductive Technology, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
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Garcia-Segura S, del Rey J, Closa L, Garcia-Martínez I, Hobeich C, Castel AB, Vidal F, Benet J, Ribas-Maynou J, Oliver-Bonet M. Seminal Microbiota of Idiopathic Infertile Patients and Its Relationship With Sperm DNA Integrity. Front Cell Dev Biol 2022; 10:937157. [PMID: 35837328 PMCID: PMC9275566 DOI: 10.3389/fcell.2022.937157] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/06/2022] [Indexed: 11/17/2022] Open
Abstract
The development of new biomarkers for human male infertility is crucial to improve the diagnosis and the prognosis of this disease. Recently, seminal microbiota was shown to be related to sperm quality parameters, suggesting an effect in human fertility and postulating it as a biomarker candidate. However, its relationship to sperm DNA integrity has not been studied yet. The aim of the present study is to characterize the seminal microbiota of a western Mediterranean population and to evaluate its relationship to sperm chromatin integrity parameters, and oxidative stress. For that purpose, 14 samples from sperm donors and 42 samples from infertile idiopathic patients were obtained and were analyzed to assess the composition of the microbiota through full-length 16S rRNA gene sequencing (Illumina MiSeq platform). Microbial diversity and relative abundances were compared to classic sperm quality parameters (macroscopic semen parameters, motility, morphology and concentration), chromatin integrity (global DNA damage, double-stranded DNA breaks and DNA protamination status) and oxidative stress levels (oxidation-reduction potential). The seminal microbiota observed of these samples belonged to the phyla Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. The most abundant genera were Finegoldia, Peptoniphilus, Anaerococcus, Campylobacter, Streptococcus, Staphylococcus, Moraxella, Prevotella, Ezakiella, Corynebacterium and Lactobacillus. To our knowledge, this is the first detection of Ezakiella genus in seminal samples. Two clusters of microbial profiles were built based on a clustering analysis, and specific genera were found with different frequencies in relation to seminal quality defects. The abundances of several bacteria negatively correlate with the sperm global DNA fragmentation, most notably Moraxella, Brevundimonas and Flavobacterium. The latter two were also associated with higher sperm motility and Brevundimonas additionally with lower oxidative-reduction potential. Actinomycetaceae, Ralstonia and Paenibacillus correlated with reduced chromatin protamination status and increased double-stranded DNA fragmentation. These effects on DNA integrity coincide in many cases with the metabolism or enzymatic activities of these genera. Significant differences between fertile and infertile men were found in the relative presence of the Propionibacteriaceae family and the Cutibacterium, Rhodopseudomonas and Oligotropha genera, which supports its possible involvement in male fertility. Our findings sustain the hypothesis that the seminal microbiome has an effect on male fertility.
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Affiliation(s)
- Sergio Garcia-Segura
- Unit of Cell Biology and Medical Genetics, Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Javier del Rey
- Unit of Cell Biology and Medical Genetics, Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Laia Closa
- Histocompatibility and Immunogenetics Laboratory, Banc de Sang i Teixits (BST), Barcelona, Spain
- Medicina Transfusional, Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Iris Garcia-Martínez
- Medicina Transfusional, Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
- Grup de Coagulopaties Congènites, Banc de Sang i Teixits (BST), Barcelona, Spain
| | - Carlos Hobeich
- Medicina Transfusional, Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
- Grup de Coagulopaties Congènites, Banc de Sang i Teixits (BST), Barcelona, Spain
| | | | - Francisco Vidal
- Medicina Transfusional, Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
- Grup de Coagulopaties Congènites, Banc de Sang i Teixits (BST), Barcelona, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Barcelona, Spain
| | - Jordi Benet
- Unit of Cell Biology and Medical Genetics, Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Jordi Ribas-Maynou
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, Girona, Spain
- Unit of Cell Biology, Department of Biology, University of Girona, Girona, Spain
- *Correspondence: Jordi Ribas-Maynou, ; Maria Oliver-Bonet,
| | - Maria Oliver-Bonet
- Unit of Cell Biology and Medical Genetics, Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
- *Correspondence: Jordi Ribas-Maynou, ; Maria Oliver-Bonet,
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