Enrichment of HLA Types and Single-Nucleotide Polymorphism Associated With Non-progression in a Strictly Defined Cohort of HIV-1 Controllers

The CD56-CD16+ NK cell subset in chronic infections

Long-term human diseases can shape the immune system, and natural killer (NK) cells have been documented to differentiate into distinct subsets specifically associated with chronic virus infections. One of these subsets found in large frequencies in HIV-1 are the CD56-CD16+ NK cells, and this population's association with chronic virus infections is the subject of this review. Human NK cells are classically defined by CD56 expression, yet increasing evidence supports the NK cell status of the CD56-CD16+ subset which we discuss herein. We then discuss the evidence linking CD56-CD16+ NK cells to chronic virus infections, and the potential immunological pathways that are altered by long-term infection that could be inducing the population's differentiation. An important aspect of NK cell regulation is their interaction with human leukocyte antigen (HLA) class-I molecules, and we highlight work that indicates both virus and genetic-mediated variations in HLA expression that have been linked to CD56-CD16+ NK cell frequencies. Finally, we offer a perspective on CD56-CD16+ NK cell function, taking into account recent work that implies the subset is comparable to CD56+CD16+ NK cell functionality in antibody-dependent cell cytotoxicity response, and the definition of CD56-CD16+ NK cell subpopulations with varying degranulation capacity against target cells.

FcγRIIIa receptor polymorphism influences NK cell mediated ADCC activity against HIV

BACKGROUND

HIV-specific Antibody Dependent Cell Cytotoxicity (ADCC) has shown to be important in HIV control and resistance. The ADCC is mediated primarily by natural killer cell activated through the binding of FcγRIIIa receptor to the Fc portion of antibody bound to the antigen expressed on the infected cells. However, no data is available on the influence of the polymorphism in FcγRIIIa receptor on HIV-specific ADCC response.

METHODS

The Sanger's method of sequencing was used to sequence the exon of FcγRIIIa receptor while the ADCC activity was determined using NK cell activation assay. The polymorphism in FcγRIIIa receptor was assessed in HIV-infected Indian individuals with or without HIV-specific ADCC antibodies and its influence on the magnitude of HIV-specific ADCC responses was analyzed.

RESULTS

Two polymorphisms: V176F (rs396991) and Y158H (rs396716) were observed. The Y158H polymorphism is reported for the first time in Indian population. Both, V176F (V/V genotype) (p = 0.004) and Y158H (Y/H genotype) (p = 0.032) were found to be significantly associated with higher magnitude of HIV-specific ADCC response.

CONCLUSION

The study underscores the role of polymorphism in the FcγRIIIa receptor on HIV-specific ADCC response and suggests that the screening of the individuals for FcγRIIIa-V176F and Y158H polymorphisms could be useful for prediction of efficient treatment in monoclonal antibody-based therapies aimed at ADCC in HIV infection.

Deciphering natural control of HIV-1: A valuable strategy to achieve antiretroviral therapy termination

Antiretroviral therapy (ART) has dramatically reduced HIV-1-associated morbidity and mortality, and has transformed HIV-1 infection into a manageable chronic condition by suppressing viral replication. However, despite recent patient care improvements, ART still fails to cure HIV-1 infection due to the inability to counteract immune defects and metabolic disturbances that are associated with residual inflammation alongside viral persistence. Life-long drug administration also results in multiple side-effects in patients including lipodystrophy and insulin resistance. Thus, it is critical to find new ways to reduce the length of treatment and facilitate the termination of ART, for example by boosting protective immunity. The rare ability of some individuals to naturally control HIV-1 infection despite residual inflammation could be exploited to identify molecular mechanisms involved in host protection that may function as potential therapeutic targets. In this review, we highlight evidence illustrating the molecular and metabolic advantages of HIV-1 controllers over ART treated patients that contribute to the maintenance of effective antiviral immunity.

Class-modeling analysis reveals T-cell homeostasis disturbances involved in loss of immune control in elite controllers

BACKGROUND

Despite long-lasting HIV replication control, a significant proportion of elite controller (EC) patients may experience CD4 T-cell loss. Discovering perturbations in immunological parameters could help our understanding of the mechanisms that may be operating in those patients experiencing loss of immunological control.

METHODS

A case-control study was performed to evaluate if alterations in different T-cell homeostatic parameters can predict CD4 T-cell loss in ECs by comparing data from EC patients showing significant CD4 decline (cases) and EC patients showing stable CD4 counts (controls). The partial least-squares-class modeling (PLS-CM) statistical methodology was employed to discriminate between the two groups of patients, and as a predictive model.

RESULTS

Herein, we show that among T-cell homeostatic alterations, lower levels of naïve and recent thymic emigrant subsets of CD8 cells and higher levels of effector and senescent subsets of CD8 cells as well as higher levels of exhaustion of CD4 cells, measured prior to CD4 T-cell loss, predict the loss of immunological control.

CONCLUSIONS

These data indicate that the parameters of T-cell homeostasis may identify those EC patients with a higher proclivity to CD4 T-cell loss. Our results may open new avenues for understanding the mechanisms underlying immunological progression despite HIV replication control, and eventually, for finding a functional cure through immune-based clinical trials.