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Testicular microbiome in azoospermic men-first evidence of the impact of an altered microenvironment.

ABSTRACT: STUDY QUESTION:Given the relevant role of the extracellular microenvironment in regulating tissue homeostasis, is testicular bacterial microbiome (BM) associated with germ cell aplasia in idiopathic non-obstructive azoospermia (iNOA)? SUMMARY ANSWER:A steady increase of dysbiosis was observed among testis with normal spermatogenesis vs. iNOA with positive sperm retrieval and iNOA with complete germ cell aplasia. WHAT IS KNOWN ALREADY:Tissue-associated BM has been reported to be a biologically important extracellular microenvironment component for numerous body habitats, but not yet for the human testis. STUDY DESIGN, SIZE, DURATION:Cross-sectional study, investigating tissue-associated BM in the testis of (i) five men with iNOA and negative sperm retrieval at microdissection testicular sperm extraction (microTESE); (ii) five men with iNOA and positive sperm retrieval at microTESE; and (iii) five normozoospermic men upon orchiectomy. Every testicular specimen was histologically classified and analyzed in terms of bacterial community. PARTICIPANTS/MATERIALS, SETTING, METHODS:Massive ultra-deep pyrosequencing was applied to investigate testis microbiome. Metagenome was analyzed using Quantitative Insights Into Microbial Ecology (QIIME). Tissue-associated bacterial load was quantified by digital droplet PCR. MAIN RESULTS AND THE ROLE OF CHANCE:Normozoospermic men showed small amounts of bacteria in the testis, with Actinobacteria, Bacteroidetes, Firmicutes Proteobacteria as the dominating phyla; iNOA individuals had increased amounts of bacterial DNA (P = 0.02), associated with decreased taxa richness due to the lack of Bacteroidetes and Proteobacteria (P = 2 × 10-5). Specimens with negative sperm retrieval at microTESE depicted complete germ cell aplasia and a further decrease in terms of Firmicutes and Clostridia (P < 0.05), a complete lack of Peptoniphilus asaccharolyticus, but increased amount of Actinobacteria. LIMITATIONS, REASONS FOR CAUTION:The limited number of specimens analyzed in this preliminary study deserves external validation. The paraneoplastic microenvironment could have an impact on the residential bacterial flora. WIDER IMPLICATION OF THE FINDINGS:Human testicular microenvironment is not microbiologically sterile, containing low amounts of Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. A dysbiotic bacterial community was associated with iNOA and complete germ cell aplasia. Novel findings on testicular BM could support future translational therapies of male-factor infertility. STUDY FUNDING/COMPETING INTEREST(S):This work was supported by URI-Urological Research Institute free funds. Authors declared no conflict of interest. TRIAL REGISTRATION NUMBER:N/A.

SUBMITTER: Alfano M

PROVIDER: S-EPMC6012977 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Men presenting with non-obstructive azoospermia are the most challenging clinical scenario for an infertile couple. Intracytoplasmic Sperm Injection (ICSI) with testicular sperm retrieval gave a chance for biological fatherhood once sperm can be found, but unfortunately sperm recovery rate (SSR) is something near 50%, leading to a discussion about what surgical retrieval technique is the best. Historically sperm have been retrieved using conventional Testicular Sperm Extraction (c-TESE), Testicular Sperm Aspiration (TESA), a combination of Testicular Fine Needle Aspiration (TfNA)/c-TESE, Testicular Microdissection (TM) and Open Testicular Mapping (OTEM). c-TESE published in 1995 by Devroey and cols. consists of testis delivery, a large unique albuginea incision and extraction of a portion from the majority of testicular tubules. TESA published in 1996 by Lewin and cols. is done percutaneously using a 21–23 gauge needle and a syringe to aspire testicular tubules. TfNA was published in 1965 by Obrant and Persson as an aspiration biopsy and cytological exam to verify sperm production. In 1999 Turek and cols. published the use of TfNA combined with c-TESE for sperm retrieval. In 1999, Peter Schlegel published a technique using a microsurgical approach to identify more probable sperm production areas inside the testicle that could be excised with better precision and less tissue. OTEM is a multiple biopsy approach, published in 2020 by Vieira and cols., based on TfNA principles but done at the same time without albuginea opening or surgical microscope need. Since Testicular Microdissection publication, the method became the gold standard for sperm retrieval, allowing superior SSR with minimal tissue removal, but the amount of testicular dissection to find more probable spermatogenesis areas, difficulties in comparative design studies, diversity TM results among doctors and other methods that can achieve very similar results we question TM superiority. The objective is review existing literature and discuss advantages and disadvantages of all the methods for sperm retrieval in non-obstructive azoospermia.

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Testicular microbiome in azoospermic men-first evidence of the impact of an altered microenvironment.

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