Gut barrier structure, mucosal immunity and intestinal microbiota in the pathogenesis and treatment of HIV infection

Microbiota and Probiotics in Health and HIV Infection

Microbiota play a key role in various body functions, as well as in physiological, metabolic, and immunological processes, through different mechanisms such as the regulation of the development and/or functions of different types of immune cells in the intestines. Evidence indicates that alteration in the gut microbiota can influence infectious and non-infectious diseases. Bacteria that reside on the mucosal surface or within the mucus layer interact with the host immune system, thus, a healthy gut microbiota is essential for the development of mucosal immunity. In patients with human immunodeficiency virus (HIV), including those who control their disease with antiretroviral drugs (ART), the gut microbiome is very different than the microbiome of those not infected with HIV. Recent data suggests that, for these patients, dysbiosis may lead to a breakdown in the gut’s immunologic activity, causing systemic bacteria diffusion and inflammation. Since in HIV-infected patients in this state, including those in ART therapy, the treatment of gastrointestinal tract disorders is frustrating, many studies are in progress to investigate the ability of probiotics to modulate epithelial barrier functions, microbiota composition, and microbial translocation. This mini-review analyzed the use of probiotics to prevent and attenuate several gastrointestinal manifestations and to improve gut-associated lymphoid tissue (GALT) immunity in HIV infection.

HIV and its relationship to insulin resistance and lipid abnormalities

Antiretroviral therapy has revolutionized the care of people with human immunodeficiency virus (HIV) by reducing morbidity and mortality from acquired immunodeficiency syndrome-related conditions. Despite longer life expectancy, however, HIV-infected individuals continue to have a higher risk of death compared with the general population. This has been attributed to the increasing incidence of noncommunicable diseases, in particular, atherosclerotic cardiovascular diseases. This is driven, in part, by the emergence of metabolic disorders, particularly dyslipidemia, insulin resistance, and lipodystrophy, in those on antiretroviral therapy. The pathogenesis of these metabolic derangements is complex and multifactorial, and could be a consequence of an interplay between traditional age-related risk factors, HIV infection, antiretroviral therapy effects, and the inflammatory state and immune activation in this population. Understanding the contributions of each of these factors could not just impact the current management of these individuals and help mitigate the risk for premature cardiovascular disease, but also shape the future direction of research in HIV.

Marked Enteropathy in an Accelerated Macaque Model of AIDS

Enteropathy in HIV infection is not eliminated with combination antiretroviral therapy and is possibly linked to microbial translocation. We used a rapidly progressing SIV/pigtailed macaque model of HIV to examine enteropathy and microbial translocation. Histologic evidence of intestinal disease was observed in only half of infected macaques during late-stage infection (LSI). Combination antiretroviral therapy initiated during acute infection prevented intestinal disease. In the ileum and colon, enteropathy was associated with increased caspase-3 staining, decreased CD3⁺ T cells, and increased SIV-infected cells. CD3⁺ T cells were preserved in LSI animals without intestinal disease, and levels of CD3 staining in all LSI animals strongly correlated with the number of infected cells in the intestine and plasma viral load. Unexpectedly, there was little evidence of microbial translocation as measured by soluble CD14, soluble CD163, lipopolysaccharide binding protein, and microbial 16s ribosomal DNA. Loss of epithelial integrity indicated by loss of the tight junction protein claudin-3 was not observed during acute infection despite significantly fewer T cells. Claudin-3 was reduced in LSI animals with severe intestinal disease but did not correlate with increased microbial translocation. LSI animals that did not develop intestinal disease had increased T-cell intracytoplasmic antigen 1-positive cytotoxic T lymphocytes, suggesting a robust adaptive cytotoxic T-lymphocyte response may, in part, confer resilience to SIV-induced intestinal damage.