The functional consequences of the microbiome in HIV: insights from metabolomic studies

Purpose of review It is critical to gain insight into the metabolic pathways by which the microbiota might influence HIV immunopathogenesis to exploit host-microbiota interactions. The aim of this review is to sketch a very broad picture of recent advances in our knowledge of how HIV might affect the microbiota, with a focus on specific gene products, particularly, metabolites produced by the microbiota that may affect HIV immunopathogenesis. Recent findings First, we describe the different approaches used to explore imbalances in effector microbial products during HIV infection. Then, we review the mechanisms by which the microbiota might affect HIV immunopathogenesis. We cover several aspects of HIV immunopathogenesis, including systemic inflammation, mucosal immunity, enterocyte barrier integrity, HIV persistence and effects on HIV-specific humoral and cytotoxic responses. The altered interplay between mucosal immunity and dysbiotic bacteria helps to explain poorly understood observations in HIV infection, including susceptibility to HIV acquisition or the risk of HPV-related cancers, lung infections and cardiovascular disease. Summary Although there is an urgent need to standardize the methods used for assessing the functional level of the microbiota, it is recognized that functional modulation of the microbiota for therapeutic purposes should be evaluated to improve HIV care.