Inflammation, NK Cells, Antisense Protein and Exosomes, and Correlation With Immune Response During HIV Infection

Overview

More than 90% of HIV-infected patients on antiretroviral therapy have an undetectable viral load. However, approximately 15% of these individuals do not sufficiently restore their TCD4 lymphocytes and have an unfavorable CD4/CD8 ratio despite good adherence and an undetectable viral load. Factors associated with immunovirological discordance include low CD4 cell counts prior to antiretroviral therapy, low CD4/CD8 ratios and positive cytomegalovirus (CMV) serology. These patients are at risk of significant non-AIDS events and mortality. The anti-sense protein (ASP) is synthesized from the anti-sense strand of HIV-1. A cytotoxic anti-ASP response of CD8 T lymphocytes and anti-ASP antibodies have been demonstrated in infected patients. The conservation of the ASP gene in HIV-1, the virus responsible for the pandemic, suggests that its maintenance confers an advantage to the virus. ASP induces an inflammatory phenotype in surrounding cells. ASP can be externalized by the cell through its interaction with its cellular partner Bat-3. Once externalized in soluble or exosomal form, Bat-3 has the ability to regulate NK cell activity. During HIV infection, NK functions are disrupted, including those related to the expression of the Bat-3 receptor, NKp30. In patients, the inflammatory phenomenon is strongly associated with chronic HIV-1 infection. The efficacy of antiviral treatments does not allow a complete normalization of either the immune system function or the inflammatory status of the patient. The observed effect of ASP on inflammation raises the question of the involvement of ASP in the maintenance of a chronic inflammatory state in patients under treatment. Increased inflammation has also been associated in HIV-infected patients with elevated plasma exosome levels. In patients undergoing treatment, chronic inflammation remains a major problem and an important source of comorbidities (cardiovascular in particular) and probably contributes to the immunovirological non-response in immunodiscordant HIV-infected patients. It is hypothesized that ASP bound to its cellular partner Bat-3 in exosomes would disrupt the cytotoxic activity of NK cells, sustain inflammation and have a deleterious effect on immune reconstitution.

The main objective of the project is to characterize the presence of ex vivo NK cell perturbations in patients living with HIV (PLHIV) with immunovirological discordance, in relation to ASP expression and plasmatic exosomes. The secondary objectives will be to identify new biological parameters to study and to establish mechanistic hypothesis explaining the results obtained during the study. The study has a pathophysiological aim and is approved by the committee for the protection of individuals. Two groups of patients will be constituted: one group of PLWHIV with immunovirological discordance (20 patients) and the other group of PLWHIV with a good immune reconstitution (40 patients).