mBIO：研究确定男性感染艾滋病的又一大危险因素
来自乔治华盛顿大学梅肯研究院公共卫生学院的研究人员发布了他们的最新研究报告，报告中指出男性包皮中存在的某种细菌将艾滋病感染风险提高了63%。研究的完整报告发表于《生物学》期刊中，此次研究首次将艾滋病风险与阴茎细菌想联系，找到并确定了男性感染艾滋病毒前所未有的危险因素。此外，研究人员认为，这种风险因素可能来自于性传播。
研究表明微生物生活在在人类身体的各个部位，与人们的健康息息相关，阴茎微生物的作用也与男性健康有关。通过检查男性包皮细菌，即感染艾滋病病毒的风险因素，研究人员发现厌氧菌细菌在低氧环境下，增加感染艾滋病毒的风险。
研究人员表示：“这项研究首次表明，以阴茎为栖息地的细菌可能是男性感染艾滋病毒的一个独立危险因素，除此之外，还有更多不耐氧细菌都与艾滋病风险增加有关。
针对这项研究，科学家进行了为期两年的试验，参与者来自于乌干达的异性恋男性。研究人员利用分子生物学方法，测量了生活在包皮中的大量细菌，他们发现在四个厌氧细菌普氏菌属会将感染艾滋病毒的风险增加63%。
这一发现使研究人员将男性艾滋病的预防和治疗靶向阴茎，通过减少生殖器上的厌氧细菌，降低免疫反应，从而降低艾滋病毒的感染风险。
Cindy M. Liua, Jessica L. Prodger, Aaron A. R. Tobiand,et al.Penile Anaerobic Dysbiosis as a Risk Factor for HIV Infection. mBio.2017. 8:e00996-17. https://doi.org/10.1128/mBio.00996-17.
ABSTRACT
Sexual transmission of HIV requires exposure to the virus and infection of activated mucosal immune cells, specifically CD4+ T cells or dendritic cells. The foreskin is a major site of viral entry in heterosexual transmission of HIV. Although the probability of acquiring HIV from a sexual encounter is low, the risk varies even after adjusting for known HIV risk factors. The genital microbiome may account for some of the variability in risk by interacting with the host immune system to trigger inflammatory responses that mediate the infection of mucosal immune cells. We conducted a case-control study of uncircumcised participants nested within a randomized-controlled trial of male circumcision in Rakai, Uganda. Using penile (coronal sulcus) swabs collected by study personnel at trial enrollment, we characterized the penile microbiome by sequencing and real-time PCR and cytokine levels by electrochemiluminescence assays. The absolute abundances of penile anaerobes at enrollment were associated with later risk of HIV seroconversion, with a 10-fold increase in Prevotella, Dialister, Finegoldia, and Peptoniphilus increasing the odds of HIV acquisition by 54 to 63%, after controlling for other known HIV risk factors. Increased abundances of anaerobic bacteria were also correlated with increased cytokines, including interleukin-8, which can trigger an inflammatory response that recruits susceptible immune cells, suggesting a mechanism underlying the increased risk. These same anaerobic genera can be shared between heterosexual partners and are associated with increased HIV acquisition in women, pointing to anaerobic dysbiosis in the genital microbiome and an accompanying inflammatory response as a novel, independent, and transmissible risk factor for HIV infection.
IMPORTANCE
We found that uncircumcised men who became infected by HIV during a 2-year clinical trial had higher levels of penile anaerobes than uncircumcised men who remained HIV negative. We also found that having higher levels of penile anaerobes was also associated with higher production of immune factors that recruit HIV target cells to the foreskin, suggesting that anaerobes may modify HIV risk by triggering inflammation. These anaerobes are known to be shared by heterosexual partners and are associated with HIV risk in women. Therefore, penile anaerobes may be a sexually transmissible risk factor for HIV, and modifying the penile microbiome could potentially reduce HIV acquisition in both men and women.
来源：来宝网
本期编辑：Tony