KIR-HLA genotypes in HIV-infected patients lacking immunological recovery despite effective antiretroviral therapy

Multi-omics in HIV: searching insights to understand immunological non-response in PLHIV

Antiretroviral therapy (ART) induces persistent suppression of HIV-1 replication and gradual recovery of T-cell counts, and consequently, morbidity and mortality from HIV-related illnesses have been significantly reduced. However, in approximately 30% of people living with HIV (PLHIV) on ART, CD4+ T-cell counts fail to normalize despite ART and complete suppression of HIV viral load, resulting in severe immune dysfunction, which may represent an increased risk of clinical progression to AIDS and non-AIDS events as well as increased mortality. These patients are referred to as "immune inadequate responders", "immunodiscordant responders" or "immune nonresponders (INR)". The molecular mechanisms underlying poor CD4+ T-cell recovery are still unclear. In this sense, the use of omics sciences has shed light on possible factors involved in the activity and metabolic dysregulation of immune cells during the failure of CD4+ T-cell recovery in INR. Moreover, identification of key molecules by omics approaches allows for the proposal of potential biomarkers or therapeutic targets to improve CD4+ T-cell recovery and the quality of life of these patients. Hence, this review aimed to summarize the information obtained through different omics concerning the molecular factors and pathways associated with the INR phenotype to better understand the complexity of this immunological status in HIV infection.

CD4+ T lymphocyte recovery in the modern antiretroviral therapy era: Toward a new threshold for defining immunological non-responders

Introduction

Despite the high level of efficacy of modern antiretroviral therapy (ART) in reducing HIV viremia and the control of viral replication, some people living with HIV (PLWH) do not recover their CD4+ T cell count.

Methods

To evaluate the frequency and predictive factors of discordant immune responses, we performed a retrospective cohort study of 324 antiretroviral-naïve PLWH who initiated first-line ART between 2008 and 2018 and maintained HIV RNA < 50 copies/ml during 36 months of follow-up. PLWH were defined as immunological non-responders (INRs) when CD4+ T cell count was < 20% compared with baseline (INR20%), or < 500 cells/mm3 (INR500) or < 200 cells/mm3 (INR200) at 36 months.

Results

The prevalence of INR20%, INR500, and INR200 was 12.5%, 34.6%, and 1.5%, respectively. After adjustment for possible confounders, CD4 nadir showed a significant association with all INR definitions, with lower values predicting INR500 (aOR 0.98, 95% CI 0.98–0.99, p < 0.001) and INR200 (aOR 0.98, 95% CI 0.95–1.01, p = 0.096). Moreover, a higher baseline CD4/CD8 ratio was inversely related to the probability of being INR500 (OR 0.03, 95% CI 0.01–0.12, p < 0.001) and INR200 (OR 0.002, 95% CI 18–7–67.72, p = 0.255). By contrast, INR20% had a higher CD4 nadir and CD4/CD8 ratio than other INRs, suggesting the identification of an heterogenous population with such definition.

Discussion

The present study highlights how INR200 has become rare in the contemporary ART era, and about one-third of PLWH meet the criteria for INR500. Overcoming the threshold of 500 CD4/mm3 could be an appropriate definition of immune response, in contrast with the older definitions of INR200 and INR20%. Early diagnosis and rapid treatment initiation, before CD4 counts and the CD4/CD8 ratio begin to decline, are critical for achieving an optimal immune response.

HLA-B*13, B*35 and B*39 Alleles Are Closely Associated With the Lack of Response to ART in HIV Infection: A Cohort Study in a Population of Northern Brazil

Introduction

Immune reconstitution failure after HIV treatment is a multifactorial phenomenon that may also be associated with a single polymorphism of human leukocyte antigen (HLA); however, few reports include patients from the Brazilian Amazon. Our objective was to evaluate the association of the immunogenic profile of the “classical” HLA-I and HLA-II loci with treatment nonresponse in a regional cohort monitored over 24 months since HIV diagnosis.

Materials and Methods

Treatment-free participants from reference centers in the state of Pará, Brazil, were enrolled. Infection screening was performed using enzyme immunoassays (Murex AG/AB Combination DiaSorin, UK) and confirmed by immunoblots (Bio-Manguinhos, FIOCRUZ). Plasma viral load was quantified by real-time PCR (ABBOTT, Chicago, Illinois, USA). CD4⁺/CD8⁺ T lymphocyte quantification was performed by immunophenotyping and flow cytometry (BD Biosciences, San Jose, CA, USA). Infection was monitored via test and logistics platforms (SISCEL and SICLOM). Therapeutic response failure was inferred based on CD4⁺ T lymphocyte quantification after 1 year of therapy. Loci A, B and DRB1 were genotyped using PCR-SSO (One Lambda Inc., Canoga Park, CA, USA). Statistical tests were applied using GENEPOP, GraphPad Prism 8.4.3 and BioEstat 5.3.

Results

Of the 270 patients monitored, 134 responded to treatment (CD4⁺ ≥ 500 cells/µL), and 136 did not respond to treatment (CD4⁺ < 500 cells/µL). The allele frequencies of the loci were similar to heterogeneous populations. The allelic profile of locus B was statistically associated with treatment nonresponse, and the B*13, B*35 and B*39 alleles had the greatest probabilistic influence. The B*13 allele had the highest risk of treatment nonresponse, and carriers of the allele had a detectable viral load and a CD4+ T lymphocyte count less than 400 cells/µL with up to 2 years of therapy. The B*13 allele was associated with a switch in treatment regimens, preferably to efavirenz (EFZ)-based regimens, and among those who switched regimens, half had a history of coinfection with tuberculosis.

Conclusions

The allelic variants of the B locus are more associated with non-response to therapy in people living with HIV (PLHIV) from a heterogeneous population in the Brazilian Amazon.

NK Cell Subpopulations and Receptor Expression in Recovering SARS-CoV-2 Infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the pandemic of coronavirus disease (COVID-19). Whereas in most cases COVID-19 is asymptomatic or pauci-symptomatic, extremely severe clinical forms are observed. In this case, complex immune dysregulations and an excessive inflammatory response are reported and are the main cause of morbidity and mortality. Natural killer cells are key players in the control of viral infection, and their activity is regulated by a tight balance between activating and inhibitory receptors; an alteration of NK activity was suggested to be associated with the development of severe forms of COVID-19. In this study, we analyzed peripheral NK cell subpopulations and the expression of activating and inhibitory receptors in 30 patients suffering from neurological conditions who recovered from mild, moderate, or severe SARS-CoV-2 infection, comparing the results to those of 10 SARS-CoV-2-uninfected patients. Results showed that an expansion of NK subset with lower cytolytic activity and an augmented expression of the 2DL1 inhibitory receptor, particularly when in association with the C2 ligand (KIR2DL1-C2), characterized the immunological scenario of severe COVID-19 infection. An increase of NK expressing the ILT2 inhibitory receptor was instead seen in patients recovering from mild or moderate infection compared to controls. Results herein suggest that the KIR2DL1-C2 NK inhibitory complex is a risk factor toward the development of severe form of COVID-19. Our results confirm that a complex alteration of NK activity is present in COVID-19 infection and offer a molecular explanation for this observation.

Definition of Immunological Nonresponse to Antiretroviral Therapy: A Systematic Review

BACKGROUND

Terms and criteria to classify people living with HIV on antiretroviral therapy who fail to achieve satisfactory CD4 T-cell counts are heterogeneous, and need revision and summarization.

METHODS

We performed a systematic review of PubMed original research articles containing a set of predefined terms, published in English between January 2009 and September 2018. The search retrieved initially 1360 studies, of which 103 were eligible. The representative terminology and criteria were extracted and analyzed.

RESULTS

Twenty-two terms and 73 criteria to define the condition were identified. The most frequent term was "immunological nonresponders" and the most frequent criterion was "CD4 T-cell count <350 cells/µL after ≥24 months of virologic suppression." Most criteria use CD4+ T-cell counts as a surrogate, either as an absolute value or as a change after a defined period of time [corrected]. Distinct values and time points were used. Only 9 of the 73 criteria were used by more than one independent research team. Herein we propose 2 criteria that could help to reach a consensus.

CONCLUSIONS

The high disparity in terms and criteria here reported precludes data aggregation and progression of the knowledge on this condition, because it renders impossible to compare data from different studies. This review will foster the discussion of terms and criteria to achieve a consensual definition.

Genetic variation in CCR2 and CXCL12 genes impacts on CD4 restoration in patients initiating cART with advanced immunesupression

OBJECTIVE

We investigated the association of genetic polymorphisms in chemokine and chemokine receptor genes with poor immunological recovery in HIV patients starting combined antiretroviral therapy (cART) with low CD4 T-cell counts.

METHODS

A case-control study was conducted in 412 HIV-infected patients starting cART with CD4 T-cell count <200 cells/μL and successful viral control for two years. CD4 count increase below 200 cells/μL after two years on cART was used to define INR (immunological non-responder) patients. Polymorphisms in CXCL12, CCL5 and CCR2 genes were genotyped using sequenom's MassARRAY platform.

RESULTS

Thirty two percent (134/412) of patients were classified as INR. After adjusting by age, route of HIV infection, length of infection before cART and viral hepatitis coinfection, CCR2 rs1799864-AG genotype was significantly associated with INR status (OR [95% CI]: 1.80 [1.04-3.11]; p = 0.04), and CXCL12 rs1801157-TT genotype showed a trend (OR [95% CI]: 2.47 [0.96-6.35]; p = 0.06).

CONCLUSIONS

CCR2 rs1799864-AG or CXCL12 rs1801157-TT genotypes influence on the probability of poor CD4 recovery in the population of HIV patients starting cART with low CD4 counts. Genotyping of these polymorphisms could be used to estimate the risk of poor CD4 restoration, mainly in patients who are diagnosed late in the course of infection.

KIR and HLA-C Genetic Polymorphisms Influence Plasma IP-10 Concentration in Antiretroviral Therapy-Naive HIV-Infected Adult Zimbabweans

Past studies on the relationship between Killer cell Immunoglobulin-like Receptor (KIR) and Human Leukocyte Antigen (HLA) genetic variation and chronic immune activation (CIA) in HIV infection are not uniformly consistent. Moreover, interferon-γ-induced protein 10 (IP-10) is a soluble biomarker of immune activation, with high plasma concentrations predicting accelerated disease progression in HIV infection. Thus, we investigated the association of KIR and HLA-C genetic polymorphisms with plasma IP-10 concentration in 183 treatment-naive chronically HIV-infected adults of Bantu origin from Zimbabwe. KIR genetic variation was determined using allele-specific primer PCR while HLA-C typing was characterized by sequencing. Plasma IP-10 was quantified using enzyme-linked immunosorbent assay. The KIR2DL3 gene was significantly associated with CIA as observed from IP-10 concentrations among KIR2DL3 carriers (265.20 pg/mL, IQR: 179.99-385.19) compared with KIR2DL3 noncarriers (183.56 pg/mL; IQR: 110.98-230.81; p = 0.001) and among KIR2DL3+HLA-C2 carriers (226.23 pg/mL, IQR: 187.96-394.73) compared with KIR2DL3+HLA-C2 noncarriers (212.86 pg/mL, IQR: 160.15-344.99; p = 0.017), respectively. Similarly, IP-10 concentrations were significantly higher (p = 0.030) in the KIR3DS1 carriers (313.86 pg/mL, IQR: 230.05-469.20) compared with KIR3DS1 noncarriers (246.01 pg/mL, IQR: 169.58-373.32). Thus, KIR and HLA-C could be playing important roles in HIV-associated immune activation. The elevation of IP-10 in KIR2DL3 and KIR2DL3+C2 could potentially be explained by increased IFN-γ secretion from activated NK cell activation due to the absence of KIR2DL3's cognate C1 ligand. To the best of our knowledge, this is the first study on a potential link between KIR and HLA-C genetic determinants and plasma IP-10 concentration in this population sample. Future studies are called for in other world populations for biomarkers of disease progression and mechanisms of IP-10 variability in HIV infection.

Inhibitory natural killer cell receptor KIR3DL1 with its ligand Bw4 constraints HIV-1 disease among South Indians

OBJECTIVE

To investigate the role of genotypic and phenotypic characteristics of killer cell immunoglobulin-like receptors (KIRs) and their human leukocyte antigen (HLA) class-1 ligands in HIV-1 disease progression.

STUDY DESIGN AND METHODS

This is a nested case-control study including 347 HIV seropositive (HIV-1+) individuals from South India constituting 45 long-term nonprogressors (LTNPs) and 302 disease progressors. KIR genotyping was performed by multiplex sequence-specific primer-directed PCR (SSP-PCR). Phenotypic expressions of KIR3DL1/S1 was studied using multiparametric flow cytometry assay. HLA-Bw4 and Bw6 epitopes were determined by ARMS-PCR. HLA-Bw4I80, HLA-Bw4T80, HLA-C1, HLA-C2, and HLA-Aw4 were genotyped using SSP-PCR. Serum levels of IFN-γ was quantified using ELISA method.

RESULTS

Overall, 37 different KIR genotypes were observed and the distribution of genotypes with AB-AB (OR = 2.2, P = 0.033) constellations showed significant increase among LTNPs. The frequencies of 3DL1-2DL3-2DL5 (OR = 2.2, Pc = 0.031), 3DL1-Bw4/Aw4 (OR = 2.49, Pc = 0.019), homozygous Bw4 (OR = 2.422, Pc = 0.011) were observed higher in LTNPs and 2DS1-2DS2-2DS3 (OR =  0.475, Pc = 0.03), homozygous Bw6 (OR = 0.413, Pc = 0.011) were higher in the disease progressors. Flow cytometry assay showed the increased expression and maintenance of 3DL1/S1+NK cells in LTNPs (P = 0.0001). Further the expansion of 3DS1+NK cells was higher than 3DL1+NK cells in the heterozygous 3DL1/S1 LTNPs (P = 0.001).

CONCLUSION

The inhibitory receptor 3DL1 with Bw4 and its A-haplotype defining KIR genes (2DL3/L5) confers protection against HIV-1 disease progression. An increased expression and maintenance of 3DL1/S1+ natural killer cells may contribute to the efficient activation of the natural killer cells and subsequent long-term nonprogression (LTNPn) to the disease.

Activating KIRs and NKG2C in Viral Infections: Toward NK Cell Memory?

Natural killer (NK) cells are important players in the immune defense against viral infections. The contribution of activating killer immunoglobulin-like receptors (KIRs) and CD94/NKG2C in regulating anti-viral responses has recently emerged. Thus, in the hematopoietic stem cell transplantation setting, the presence of donor activating KIRs (aKIRs) may protect against viral infections, while in HIV-infected individuals, KIR3DS1, in combination with HLA-Bw4-I80, results in reduction of viral progression. Since, studies have been performed mainly at the genetic or transcriptional level, the effective size, the function, and the "licensing" status of NK cells expressing aKIRs, as well as the nature of their viral ligands, require further investigation. Certain viral infections, mainly due to Human cytomegalovirus (HCMV), can deeply influence the NK cell development and function by inducing a marked expansion of mature NKG2C(+) NK cells expressing self-activating KIRs. This suggests that NKG2C and/or aKIRs are involved in the selective proliferation of this subset. The persistent, HCMV-induced, imprinting suggests that NK cells may display unexpected adaptive immune traits. The role of aKIRs and NKG2C in regulating NK cell responses and promoting a memory-like response to certain viruses is discussed.

Immune activation in the course of HIV-1 infection: Causes, phenotypes and persistence under therapy

Systemic immune activation is a striking consequence of HIV-1 infection. Even in virologically suppressed patients, some hyperactivity of the immune system and even of the endothelium and of the coagulation pathway may persist. Apart from immune deficiency, this chronic activation may contribute to various morbidities including atherothrombosis, neurocognitive disorders, liver steatosis and osteoporosis, which are currently main challenges. It is therefore of major importance to better understand the causes and the phenotypes of immune activation in the course of HIV-1 infection. In this review we will discuss the various causes of immune activation in HIV-1 infected organisms: the presence of the virus together with other microbes, eventually coming from the gut, CD4+ T cell lymphopenia, senescence and dysregulation of the immune system, and/or genetic factors. We will also describe the activation of the immune system: CD4+ and CD8+ T cells, B cells, NKT and NK cells, dendritic cells, monocytes and macrophages, and neutrophils of the inflammation cascade, as well as of the endothelium and the coagulation system. Finally, we will see that antiretroviral therapy reduces the hyperactivity of the immune and coagulation systems and the endothelial dysfunction, but often does not abolish it. A better knowledge of this phenomenon might help us to identify biomarkers predictive of non AIDS-linked comorbidities, and to define new strategies aiming at preventing their emergence.

'Emergency exit' of bone-marrow-resident CD34(+)DNAM-1(bright)CXCR4(+)-committed lymphoid precursors during chronic infection and inflammation

During chronic inflammatory disorders, a persistent natural killer (NK) cell derangement is observed. While increased cell turnover is expected, little is known about whether and how NK-cell homeostatic balance is maintained. Here, flow cytometric analysis of peripheral blood mononuclear cells in chronic inflammatory disorders, both infectious and non-infectious, reveals the presence of a CD34(+)CD226(DNAM-1)(bright)CXCR4(+) cell population displaying transcriptional signatures typical of common lymphocyte precursors and giving rise to NK-cell progenies with high expression of activating receptors and mature function and even to α/β T lymphocytes. CD34(+)CD226(bright)CXCR4(+) cells reside in bone marrow, hardly circulate in healthy donors and are absent in cord blood. Their proportion correlates with the degree of inflammation, reflecting lymphoid cell turnover/reconstitution during chronic inflammation. These findings provide insight on intermediate stages of NK-cell development, a view of emergency recruitment of cell precursors, and upgrade our understanding and monitoring of chronic inflammatory conditions.

Diversity in KIR gene repertoire in HIV-1 exposed infected and uninfected infants: A study from India

Natural killer (NK) cells have antiviral activity mediated through killer immunoglobulin receptors (KIRs). Studies have shown the importance of KIR receptors in HIV infection. However reports on association of KIR genes in HIV infection from Indian population are limited, not a single study is reported in HIV exposed uninfected (EU) and infected infants. This study compared the KIR gene repertoire of HIV-1 positive (n = 29) with EU (n = 76) infants to elucidate its association with transmission. KIR genotyping was analysed using the PCR-SSP method. Viral load of mothers, CD4 count of both mothers and infected infants were done using commercial kits. The data was analysed using SPSS software. Results revealed presence of significantly high frequencies of activating gene KIR 2DS5 (P = 0.040) and inhibitory gene KIR 2DL3 (P = 0.013) in EU infants as compared to HIV-1 positive infants, confirmed with multivariable linear regression modelling. Fifty-nine KIR genotypes were identified in these 105 infants. Nine genotypes were unique, reported for the first time. Twenty six genotypes were shared with the World populations. Twenty four genotypes were reported for the first time from India. Specific KIR genotype combinations (GIDs) were exclusively present either in HIV-1 positive (n = 19) or in EU infants (n = 30). The Linkage disequilibrium (LD) analysis shows a strong linkage between four pairs of genes in HIV-1 positive and three pairs of genes in EU infants. In conclusion, this study revealed that, besides maternal confounding factors such as ART and viral load, specific KIR genes are associated independently with perinatal HIV infection.

Multilayered HIV-1 gag-specific T-cell responses contribute to slow progression in HLA-A*30-B*13-C*06-positive patients

Objective:

The HLA-A^∗30-B^∗13-C^∗06 haplotype is reported to be associated with slow disease progression in the HIV-1-infected Northern Han Chinese population, but the mechanism remains unknown.

Design:

Gag-specific T-cell responses and gag sequencing were performed in nine B′ clade HIV-1-infected HLA-A^∗30-B^∗13-C^∗06-positive slow progressors to understand HLA-associated viral control.

Methods:

Interferon-γ ELISPOT assays were performed to determine the Gag-specific T-cell responses and cross-reactivity to variant peptides. Longitudinal HIV-1 gag sequencing was performed at the clonal level.

Results:

The overlapping peptides (OLP)-48: RQANFLGKIWPSHKGRPGNF (RL42 Gag_434-453); OLP-2: GQLDRWEKIRLRPGGKKKYR (RL42 Gag_11-30); OLP-15: VQNLQGQMVHQPISPRTLNA (RL42 Gag_135-154) and OLP-16: HQPISPRTLNAWVKVVEEKA (RL42 Gag_144-163) were dominant in HLA-A^∗30-B^∗13-C^∗06-positive patients. A new epitope [HQPISPRTL (Gag_144-152, HL9)] within OLP-15 and OLP-16 was identified. Results showed that strong cross-reactive responses to multiple immunodominant peptides were associated with better clinical outcomes. In addition, efficient cross-recognition of HL9 autologous variants developed in patients was associated with high CD4⁺ T-cell counts. However, two patients who had developed mutations to their dominant responses during the follow-up experienced decrease in CD4⁺ T-cell counts. It appears that Gag-specific T-cell responses against one or more unmutated epitopes or cross-recognition of autologous epitope variants contribute to slow disease progression in HLA-A^∗30-B^∗13-C^∗06-positive patients.

Conclusion:

We conclude that a single ‘appropriate’ Gag-specific T-cell response appears to be sufficient to protect patients from disease progression. HLA-A^∗30-B^∗13-C^∗06-positive individuals benefited from having a choice of numerous immunodominant gag epitopes for T cells to react. The study offers new insight for future design of T-cell-based HIV-1 vaccine.

Activating KIR molecules and their cognate ligands prevail in children with a diagnosis of ASD and in their mothers

The activity of natural killer (NK) cells is modulated by the interaction between killer-cell immune globulin-like receptor (KIR) proteins and their cognate HLA ligands; activated NK cells produce inflammatory cytokines and mediate innate immune responses. Activating KIR/HLA complexes (aKIR/HLA) were recently suggested to prevail in children with autism spectrum disorders (ASD), a neurodevelopmental syndrome characterized by brain and behavioral abnormalities and associated with a degree of inflammation. We verified whether such findings could be confirmed by analyzing two sample cohorts of Sardinian and continental Italian ASD children and their mothers. Results showed that aKIR/HLA are increased whereas inhibitory KIR/HLA complexes are reduced in ASD children; notably this skewing was even more significant in their mothers. KIR and HLA molecules are expressed by placental cells and by the trophoblast and their interactions result in immune activation and influence fetal, as well as central nervous system development and plasticity. Data herein suggest that in utero KIR/HLA immune interactions favor immune activation in ASD; this may play a role in the pathogenesis of the disease.

Evaluation of the pharmacogenetics of immune recovery in treated HIV-infected patients

INTRODUCTION

Combination antiretroviral therapy has markedly improved the survival rate and quality of life in patients infected with HIV due to the powerful suppressor effect that current antiretroviral drugs have on the viral load. Consequently, the immune system undergoes a substantial qualitative and quantitative improvement; and this leads to an increase in the absolute CD4(+) T-lymphocyte count and the restoration of lost T-cell responses against certain opportunistic pathogens. Unfortunately, not all patients who successfully suppress plasma viremia experience sufficient CD4(+) T-cell gain and these patients, in turn, are associated with worse outcomes. Pharmacogenetic studies have been used to investigate how a patient's genetic predisposition may affect their response to antiretroviral drugs.

AREAS COVERED

This article reviews the investigations that have been published on the association between host genetic determinants of CD4(+) T-cell gain in treated HIV-infected patients. Studies were identified through a PubMed database search. Longitudinal studies into pharmacogenetic association were specifically selected.

EXPERT OPINION

While the possibility of genetic predisposition to HIV therapeutics has potential, most studies provide inconsistent data. Inconsistency is often due to partial genetic evaluation, different categorization of poor immune recovery or due to small numbers of patients evaluated. Currently, studies still belong to the research laboratory stage and more studies are required to improve our understanding.

Associations of HLA class I antigen specificities and haplotypes with disease progression in HIV-1-infected Hans in Northern China

The human leukocyte antigen (HLA) allele frequencies, which differ among various ethnic populations, may result in population-specific effects on HIV-1 disease progression. No large-scale study has yet been conducted on the Chinese population. In this study, HLA class I antigen specificities were determined in a cohort including 105 long-term non-progressors (LTNPs) and 321 typical progressors (TPs), who were recruited from HIV-1-infected Northern Han Chinese, to determine the associations between certain HLA types and HIV-1 disease progression. The frequencies of HLA class I specificities and haplotypes among the two groups were compared using binary logistic stepwise regression. Results showed that HLA-A(∗)30-B(∗)13-C(∗)06 (OR = 0.387, P = 0.019) and B(∗)67 (OR = 0.134, P = 0.005) were associated with a long-term non-progressing condition, and C(∗)01 (OR = 2.539, P = 0.050) was overrepresented in TPs after adjusting for non-genetic factors (sex, age, the location of patients, HIV subtype and the route of infection). The influence of HLA homozygosity on HIV disease progression was also analyzed. However, homozygosity at HLA-A, HLA-B or HLA-C conferred no observable disadvantage in our study population (P = 0.730, 0.246 and 0.445, respectively). These findings suggest that the host's genetics make important contributions to HIV viral control and may help to develop peptide-based vaccines for this population.

KIR3DS1/L1 and HLA-Bw4-80I are associated with HIV disease progression among HIV typical progressors and long-term nonprogressors

Background

Natural killer (NK) cells have emerged as pivotal players in innate immunity, especially in the defense against viral infections and tumors. Killer immunoglobulin-like receptors (KIRs) – an important recognition receptor expressed on the surface of NK cells – regulate the inhibition and/or activation of NK cells after interacting with human leukocyte antigen (HLA) class I ligands. Various KIR genes might impact the prognosis of many different diseases. The implications of KIR-HLA interaction in HIV disease progression remains poorly understood.

Methods

Here, we studied KIR genotypes, mRNA levels, HLA genotypes, CD4⁺ T cell counts and viral loads in our cohort of Human Immunodeficiency Virus (HIV)-infected individuals, a group that includes HIV long-term nonprogressors (LTNPs) and typical progressors (TPs).

Results

We found that the frequency of KIR3DS1/L1 heterozygotes with HLA-Bw4-80I gene was much higher in LTNPs than in TPs (P = 0.001) and that the KIR3DL1 homozygotes without HLA-Bw4-80I gene had higher viral loads and lower CD4⁺ T cell counts (P = 0.014 and P = 0.021, respectively). Our study also confirmed that homozygosity for the HLA-Bw6 allele was associated with rapid disease progression. In addition to the aforementioned results on the DNA level, we observed that higher level expression of KIR3DS1 mRNA was in LTNP group, and that higher level expression of KIR3DL1 mRNA was in TP group.

Conclusions

Our data suggest that different KIR-HLA genotypes and different levels of transcripts associate with HIV disease progression.

Anti-apoptotic mechanisms of HIV: lessons and novel approaches to curing HIV

Past efforts at curing infection with the human immunodeficiency virus (HIV) have been blocked by the resistance of some infected cells to viral cytopathic effects and the associated development of a latent viral reservoir. Furthermore, current efforts to clear the viral reservoir by means of reactivating latent virus are hampered by the lack of cell death in the newly productively infected cells. The purpose of this review is to describe the many anti-apoptotic mechanisms of HIV, as well as the current limitations in the field. Only by understanding how infected cells avoid HIV-induced cell death can an effective strategy to kill infected cells be developed.

Neonatal natural killer cell function: relevance to antiviral immune defense

Neonates are particularly susceptible to various pathogens compared to adults, which is attributed in part to their immature innate and adaptive immunity. Natural killer cells provide first-line innate immune reactions against virus-infected cells without prior sensitization. This review updates phenotypic and functional deficiencies of neonatal cells compared to their adult counterparts and their clinical implications.

Viral, host and therapeutic factors affecting T-cell recovery in virologically controlled HIV patients

Despite suppressive combination antiretroviral therapy, a considerable proportion of HIV-infected patients do not achieve adequate immune recovery in terms of the CD4+ T-cell count, although they have controlled viremia values. Many questions remain for clinicians in the management of these patients, defined as immunological nonresponders, including questions about the mechanisms underlying the lack of immune restoration and possible therapeutic approaches to this particular group of patients.