RAB11FIP5 Expression and Altered Natural Killer Cell Function Are Associated with Induction of HIV Broadly Neutralizing Antibody Responses.

HIV-1 broadly neutralizing antibodies (bnAbs) are difficult to induce with vaccines but are generated in ∼50% of HIV-1-infected individuals. Understanding the molecular mechanisms of host control of bnAb induction is critical to vaccine design. Here, we performed a transcriptome analysis of blood mononuclear cells from 47 HIV-1-infected individuals who made bnAbs and 46 HIV-1-infected individuals who did not and identified in bnAb individuals upregulation of RAB11FIP5, encoding a Rab effector protein associated with recycling endosomes. Natural killer (NK) cells had the highest differential expression of RAB11FIP5, which was associated with greater dysregulation of NK cell subsets in bnAb subjects. NK cells from bnAb individuals had a more adaptive/dysfunctional phenotype and exhibited impaired degranulation and cytokine production that correlated with RAB11FIP5 transcript levels. Moreover, RAB11FIP5 overexpression modulated the function of NK cells. These data suggest that NK cells and Rab11 recycling endosomal transport are involved in regulation of HIV-1 bnAb development.

HIV/HBV coinfection remodels the immune landscape and natural killer cell ADCC functional responses.

BACKGROUND AND AIMS: HBV and HIV coinfection is a common occurrence globally, with significant morbidity and mortality. Both viruses lead to immune dysregulation including changes in natural killer (NK) cells, a key component of antiviral defense and a promising target for HBV cure strategies. Here we used high-throughput single-cell analysis to explore the immune cell landscape in people with HBV mono-infection and HIV/HBV coinfection, on antiviral therapy, with emphasis on identifying the distinctive characteristics of NK cell subsets that can be therapeutically harnessed. APPROACH AND RESULTS: Our data show striking differences in the transcriptional programs of NK cells. HIV/HBV coinfection was characterized by an over-representation of adaptive, KLRC2 -expressing NK cells, including a higher abundance of a chemokine-enriched ( CCL3/CCL4 ) adaptive cluster. The NK cell remodeling in HIV/HBV coinfection was reflected in enriched activation pathways, including CD3ζ phosphorylation and ZAP-70 translocation that can mediate stronger antibody-dependent cellular cytotoxicity responses and a bias toward chemokine/cytokine signaling. By contrast, HBV mono-infection imposed a stronger cytotoxic profile on NK cells and a more prominent signature of "exhaustion" with higher circulating levels of HBsAg. Phenotypic alterations in the NK cell pool in coinfection were consistent with increased "adaptiveness" and better capacity for antibody-dependent cellular cytotoxicity compared to HBV mono-infection. Overall, an adaptive NK cell signature correlated inversely with circulating levels of HBsAg and HBV-RNA in our cohort. CONCLUSIONS: This study provides new insights into the differential signature and functional profile of NK cells in HBV and HIV/HBV coinfection, highlighting pathways that can be manipulated to tailor NK cell-focused approaches to advance HBV cure strategies in different patient groups.

HIV-1 remission following CCR5Δ32/Δ32 haematopoietic stem-cell transplantation.

A cure for HIV-1 remains unattainable as only one case has been reported, a decade ago1,2. The individual-who is known as the 'Berlin patient'-underwent two allogeneic haematopoietic stem-cell transplantation (HSCT) procedures using a donor with a homozygous mutation in the HIV coreceptor CCR5 (CCR5Δ32/Δ32) to treat his acute myeloid leukaemia. Total body irradiation was given with each HSCT. Notably, it is unclear which treatment or patient parameters contributed to this case of long-term HIV remission. Here we show that HIV-1 remission may be possible with a less aggressive and toxic approach. An adult infected with HIV-1 underwent allogeneic HSCT for Hodgkin's lymphoma using cells from a CCR5Δ32/Δ32 donor. He experienced mild gut graft-versus-host disease. Antiretroviral therapy was interrupted 16 months after transplantation. HIV-1 remission has been maintained over a further 18 months. Plasma HIV-1 RNA has been undetectable at less than one copy per millilitre along with undetectable HIV-1 DNA in peripheral CD4 T lymphocytes. Quantitative viral outgrowth assays from peripheral CD4 T lymphocytes show no reactivatable virus using a total of 24 million resting CD4 T cells. CCR5-tropic, but not CXCR4-tropic, viruses were identified in HIV-1 DNA from CD4 T cells of the patient before the transplant. CD4 T cells isolated from peripheral blood after transplantation did not express CCR5 and were susceptible only to CXCR4-tropic virus ex vivo. HIV-1 Gag-specific CD4 and CD8 T cell responses were lost after transplantation, whereas cytomegalovirus-specific responses were detectable. Similarly, HIV-1-specific antibodies and avidities fell to levels comparable to those in the Berlin patient following transplantation. Although at 18 months after the interruption of treatment it is premature to conclude that this patient has been cured, these data suggest that a single allogeneic HSCT with homozygous CCR5Δ32 donor cells may be sufficient to achieve HIV-1 remission with reduced intensity conditioning and no irradiation, and the findings provide further support for the development of HIV-1 remission strategies based on preventing CCR5 expression.

Humoral and cellular responses to SARS-CoV-2 in patients with B-cell haematological malignancies improve with successive vaccination.

Patients with haematological malignancies are more likely to have poor responses to vaccination. Here we provide detailed analysis of the humoral and cellular responses to COVID-19 vaccination in 69 patients with B-cell malignancies. Measurement of anti-spike IgG in serum demonstrated a low seroconversion rate with 27.1% and 46.8% of patients seroconverting after the first and second doses of vaccine, respectively. In vitro pseudoneutralisation assays demonstrated a poor neutralising response, with 12.5% and 29.5% of patients producing a measurable neutralising titre after the first and second doses, respectively. A third dose increased seropositivity to 54.3% and neutralisation to 51.5%, while a fourth dose further increased both seropositivity and neutralisation to 87.9%. Neutralisation titres post-fourth dose showed a positive correlation with the size of the B-cell population measured by flow cytometry, suggesting an improved response correlating with recovery of the B-cell compartment after B-cell depletion treatments. In contrast, interferon gamma ELISpot analysis showed a largely intact T-cell response, with the percentage of patients producing a measurable response boosted by the second dose to 75.5%. This response was maintained thereafter, with only a small increase following the third and fourth doses, irrespective of the serological response at these timepoints.

An HLA-I signature favouring KIR-educated Natural Killer cells mediates immune control of HIV in children and contrasts with the HLA-B-restricted CD8+ T-cell-mediated immune control in adults.

Natural Killer (NK) cells contribute to HIV control in adults, but HLA-B-mediated T-cell activity has a more substantial impact on disease outcome. However, the HLA-B molecules influencing immune control in adults have less impact on paediatric infection. To investigate the contribution NK cells make to immune control, we studied >300 children living with HIV followed over two decades in South Africa. In children, HLA-B alleles associated with adult protection or disease-susceptibility did not have significant effects, whereas Bw4 (p = 0.003) and low HLA-A expression (p = 0.002) alleles were strongly associated with immunological and viral control. In a comparator adult cohort, Bw4 and HLA-A expression contributions to HIV disease outcome were dwarfed by those of protective and disease-susceptible HLA-B molecules. We next investigated the immunophenotype and effector functions of NK cells in a subset of these children using flow cytometry. Slow progression and better plasma viraemic control were also associated with high frequencies of less terminally differentiated NKG2A+NKp46+CD56dim NK cells strongly responsive to cytokine stimulation and linked with the immunogenetic signature identified. Future studies are indicated to determine whether this signature associated with immune control in early life directly facilitates functional cure in children.

T Cells Infiltrating Diseased Liver Express Ligands for the NKG2D Stress Surveillance System.

NK cells, which are highly enriched in the liver, are potent regulators of antiviral T cells and immunopathology in persistent viral infection. We investigated the role of the NKG2D axis in T cell/NK cell interactions in hepatitis B. Activated and hepatitis B virus (HBV)-specific T cells, particularly the CD4 fraction, expressed NKG2D ligands (NKG2DL), which were not found on T cells from healthy controls (p < 0.001). NKG2DL-expressing T cells were strikingly enriched within HBV-infected livers compared with the periphery or to healthy livers (p < 0.001). NKG2D+NK cells were also increased and preferentially activated in the HBV-infected liver (p < 0.001), in direct proportion to the percentage of MICA/B-expressing CD4 T cells colocated within freshly isolated liver tissue (p < 0.001). This suggests that NKG2DL induced on T cells within a diseased organ can calibrate NKG2D-dependent activation of local NK cells; furthermore, NKG2D blockade could rescue HBV-specific and MICA/B-expressing T cells from HBV-infected livers. To our knowledge, this is the first ex vivo demonstration that non-virally infected human T cells can express NKG2DL, with implications for stress surveillance by the large number of NKG2D-expressing NK cells sequestered in the liver.

Interferon Alpha Induces Sustained Changes in NK Cell Responsiveness to Hepatitis B Viral Load Suppression In Vivo.

NK cells are important antiviral effectors, highly enriched in the liver, with the potential to regulate immunopathogenesis in persistent viral infections. Here we examined whether changes in the NK pool are induced when patients with eAg-positive CHB are 'primed' with PegIFNα and importantly, whether these changes are sustained or further modulated long-term after switching to nucleos(t)ides (sequential NUC therapy), an approach currently tested in the clinic. Longitudinal sampling of a prospectively recruited cohort of patients with eAg+CHB showed that the cumulative expansion of CD56bright NK cells driven by 48-weeks of PegIFNα was maintained at higher than baseline levels throughout the subsequent 9 months of sequential NUCs. Unexpectedly, PegIFNα-expanded NK cells showed further augmentation in their expression of the activating NK cell receptors NKp30 and NKp46 during sequential NUCs. The expansion in proliferating, functional NK cells was more pronounced following sequential NUCs than in comparison cohorts of patients treated with de novo NUCs or PegIFNα only. Reduction in circulating HBsAg concentrations, a key goal in the path towards functional cure of CHB, was only achieved in those patients with enhancement of NK cell IFNγ and cytotoxicity but decrease in their expression of the death ligand TRAIL. In summary, we conclude that PegIFNα priming can expand a population of functional NK cells with an altered responsiveness to subsequent antiviral suppression by NUCs. Patients on sequential NUCs with a distinct NK cell profile show a decline in HBsAg, providing mechanistic insights for the further optimisation of treatment strategies to achieve sustained responses in CHB.

Systemic inflammation and residual viraemia in HIV-positive adults on protease inhibitor monotherapy: a cross-sectional study.

BACKGROUND: Increased levels of markers of systemic inflammation have been associated with serious non-AIDS events even in patients on fully suppressive antiretroviral therapy. We explored residual viremia and systemic inflammation markers in patients effectively treated with ritonavir-boosted protease inhibitor monotherapy (PImono). METHODS: HIV-infected adults with persistent HIV-RNA<50 copies/ml and treated with either a) PImono or b) standard triple-drug cART were recruited for this cross-sectional, exploratory study. Plasma samples were tested for high-sensitivity CRP (hsCRP), Serum Amyloid A (SAA), soluble CD14, IL-6, IL-8 and Cytochrome C. HIV-RNA was measured by real-time PCR (detection limit of 10 copies/ml). RESULTS: 81 patients were recruited (31% on PImono). Two out of 25 (8%) and 3 of 56 (5.4%) patients from the PImono and cART groups respectively had detectable HIV-RNA. Significant correlation between SAA and hsCRP was observed (0.804). No difference between groups was found on prevalence of hsCRP>3 mg/l (21% vs 20% in the PImono and cART groups respectively; p=0.577) or SAA>6.4 mg/l (38% vs 22% in the PImono and cART groups respectively; P=0.172). In a univariate analysis IL6 and IL8 levels were associated with SAA>6.4 mg/l (OR=1.74 and 1.46; 95% CI=1.00-3.03 and 1.06-2.01; p=0.051 and 0.02 respectively) and hsCRP>3 mg/l in (OR=2.00 and 1.37; 95% CI=1.09-3.69 and 1.02-1.85; p=0.026 and 0.039 respectively). CONCLUSIONS: We found no evidence of increased levels of inflammatory biomarkers or higher prevalence of residual viraemia in patients effectively suppressed on PImono as compared with patients on standard cART.

IL-10-producing regulatory B cells in the pathogenesis of chronic hepatitis B virus infection.

A regulatory subset of B cells has been found to modulate immune responses in autoimmunity, infection, and cancer, but it has not been investigated in the setting of human persistent viral infection. IL-10 is elevated in patients with chronic hepatitis B virus infection (CHB), but its cellular sources and impact on antiviral T cells have not been addressed. We investigated the role of IL-10 and regulatory B cells in the pathogenesis of CHB. Serum IL-10 levels were studied longitudinally in patients with CHB undergoing spontaneous disease flares. There was a close temporal correlation between IL-10 levels and fluctuations in viral load or liver inflammation. Blockade of IL-10 in vitro rescued polyfunctional virus-specific CD8 T cell responses. To investigate the potential contribution of regulatory B cells, their frequency was measured directly ex vivo and after exposure to stimuli relevant to hepatitis B virus (HBV) (CpG or HBV Ags). IL-10-producing B cells were enriched in patients, and their frequency correlated temporally with hepatic flares, both after stimulation and directly ex vivo. Phenotypically, these cells were predominantly immature (CD19(+)CD24(hi)CD38(hi)) ex vivo; sorted CD19(+)CD24(hi)CD38(hi) cells suppressed HBV-specific CD8 T cell responses in an IL-10-dependent manner. In summary, these data reveal a novel IL-10-producing subset of B cells able to regulate T cell immunity in CHB.

Proteomic and phenotypic characteristics of memory-like natural killer cells for cancer immunotherapy.

BACKGROUND: Human and mouse natural killer (NK) cells have been shown to develop memory-like function after short-term exposure to the cocktail of IL-12/15/18 or to overnight co-culture with some tumor cell lines. The resulting cells retain enhanced lytic ability for up to 7 days as well as after cryopreservation, and memory-like NK cells (mlNK) have been shown to induce complete remissions in patients with hematological malignancies. No single phenotype has been described for mlNK and the physiological changes induced by the short-term cytokine or tumor-priming which are responsible for these enhanced functions have not been fully characterized. Here, we have generated mlNK by cytokine and tumor-priming to find commonalities to better define the nature of NK cell "memory" in vitro and, for the first time, in vivo. METHODS: We initiated mlNK in vitro from healthy donors with cytokines (initiated cytokine-induced memory-like (iCIML)-NK) and by tumor priming (TpNK) overnight and compared them by high-dimensional flow cytometry, proteomic and metabolomic profiling. As a potential mechanism of enhanced cytolytic function, we analyzed the avidity of binding of the mlNK to NK-resistant tumors (z-Movi). We generated TpNK from healthy donors and from cancer patients to determine whether mlNK generated by interaction with a single tumor type could enhance lytic activity. Finally, we used a replication-incompetent tumor cell line (INKmune) to treat patients with myeloid leukaemias to potentiate NK cell function in vivo. RESULTS: Tumor-primed mlNK from healthy donors and patients with cancer showed increased cytotoxicity against multiple tumor cell lines in vitro, analogous to iCIML-NK cells. Multidimensional cytometry identified distinct memory-like profiles of subsets of cells with memory-like characteristics; upregulation of CD57, CD69, CD25 and ICAM1. Proteomic profiling identified 41 proteins restricted to mlNK cells and we identified candidate molecules for the basis of NK memory which can explain how mlNK overcome inhibition by resistant tumors. Finally, of five patients with myelodysplastic syndrome or refractory acute myeloid leukemia treated with INKmune, three responded to treatment with measurable increases in NK lytic function and systemic cytokines. CONCLUSIONS: NK cell "memory" is a physiological state associated with resistance to MHC-mediated inhibition, increased metabolic function, mitochondrial fitness and avidity to NK-resistant target cells.

IL-15 reprogramming compensates for NK cell mitochondrial dysfunction in HIV-1 infection.

Dynamic regulation of cellular metabolism is important for maintaining homeostasis and can directly influence immune cell function and differentiation, including NK cell responses. Persistent HIV-1 infection leads to a state of chronic immune activation, NK cell subset redistribution, and progressive NK cell dysregulation. In this study, we examined the metabolic processes that characterize NK cell subsets in HIV-1 infection, including adaptive NK cell subpopulations expressing the activating receptor NKG2C, which expand during chronic infection. These adaptive NK cells exhibit an enhanced metabolic profile in HIV-1- individuals infected with human cytomegalovirus (HCMV). However, the bioenergetic advantage of adaptive CD57+NKG2C+ NK cells is diminished during chronic HIV-1 infection, where NK cells uniformly display reduced oxidative phosphorylation (OXPHOS). Defective OXPHOS was accompanied by increased mitochondrial depolarization, structural alterations, and increased DRP-1 levels promoting fission, suggesting that mitochondrial defects are restricting the metabolic plasticity of NK cell subsets in HIV-1 infection. The metabolic requirement for the NK cell response to receptor stimulation was alleviated upon IL-15 pretreatment, which enhanced mammalian target of rapamycin complex 1 (mTORC1) activity. IL-15 priming enhanced NK cell functionality to anti-CD16 stimulation in HIV-1 infection, representing an effective strategy for pharmacologically boosting NK cell responses.

Differential boosting of innate and adaptive antiviral responses during pegylated-interferon-alpha therapy of chronic hepatitis B.

BACKGROUND & AIMS: A better understanding of the immunomodulatory effects of PegIFNα therapy could allow more rational optimisation of future therapeutic approaches in chronic HBV infection. In this study, we evaluated dynamic changes in the innate and adaptive arms of the immune system induced by PegIFNα. METHODS: PBMC were obtained from a cohort of patients with eAg-negative CHB before, during and after PegIFNα treatment. The number, phenotype and function of global and virus-specific T cells and NK cells were analyzed by flow cytometry and serum cytokines by ELISA or CBA. RESULTS: The absolute number of CD8 T cells was strikingly reduced on PegIFNα therapy (p<0.001), with a predominant loss of end-stage effectors, including CMV-specific CD8 T cells. There was no significant recovery of the exhausted HBV-specific CD8 T cell response. By contrast, PegIFNα was able to potently and cumulatively drive the proliferation and expansion in absolute numbers of CD56(bright) NK cell numbers (p<0.001), with induction of the pro-proliferative cytokine IL-15. Expanded CD56(bright) NK cells showed enhanced expression of activation markers and the activating receptor NKp46, accompanied by augmentation of TRAIL and IFN-γ expression (p<0.001). Peak virological response (temporal within individual patients and cross-sectional within the cohort) correlated with the degree of expansion of functional CD56(bright) NK cells. CONCLUSIONS: IFN-α mediates divergent effects on the innate and adaptive arms of the immune system in vivo. The efficacy of PegIFNα may be limited by its depleting effect on CD8 T cells; conversely, it can cumulatively drive proliferation, activation and antiviral potential of CD56(bright) NK cells.

Investigation into the psychological impact of the COVID-19 pandemic for people living with HIV.

BACKGROUND: People living with HIV (PLWH) report high levels of anxiety. This study assessed the prevalence of COVID-19-related anxiety in PLWH. METHODS: Participants were recruited from two UK HIV clinics (01/03/2020 - 30/05/2022) and asked to complete the Coronavirus Anxiety Scale. The proportion with scores ≥9 (cut-off for dysfunctional pandemic-related anxiety) and ≥1 (reporting of any pandemic-related anxiety) were analysed. RESULTS: 115 PLWH were included, predominantly identifying as male (83.5%, n = 96), white (58.3%, n = 67) and reporting post-secondary education (82.6%, n = 95), with a median age of 51 years (range 22-93). Median CAS score was 0, with 4.4% scoring ≥9 (n = 5). More women scored ≥9 than men (16.7% (n = 3) and 2.1% (n = 2) respectively). Black African (13.6%, n = 3) and Other Ethnic Minority PLWH (25%, n = 2) had a greater proportion of scores ≥9 than White/Asian PLWH (both 0%). SARS-CoV-2 exposure was associated with scores greater than 1 but not greater than 9. CAS score was not associated with lower CD4 (<350 cells/mm3), detectable HIV viral load (≥50 copies/ml), or a history of pre-pandemic anxiety. CONCLUSIONS: Pandemic-related anxiety was low, but we identified a sub-population reporting dysfunctional pandemic related anxiety. Future work should further investigate the psychological impact of the pandemic on this group.

Natural killer cell responses during SARS-CoV-2 infection and vaccination in people living with HIV-1.

Natural killer (NK) cell subsets with adaptive properties are emerging as regulators of vaccine-induced T and B cell responses and are specialized towards antibody-dependent functions contributing to SARS-CoV-2 control. Although HIV-1 infection is known to affect the NK cell pool, the additional impact of SARS-CoV-2 infection and/or vaccination on NK cell responses in people living with HIV (PLWH) has remained unexplored. Our data show that SARS-CoV-2 infection skews NK cells towards a more differentiated/adaptive CD57+FcεRIγ- phenotype in PLWH. A similar subset was induced following vaccination in SARS-CoV-2 naïve PLWH in addition to a CD56bright population with cytotoxic potential. Antibody-dependent NK cell function showed robust and durable responses to Spike up to 148 days post-infection, with responses enriched in adaptive NK cells. NK cell responses were further boosted by the first vaccine dose in SARS-CoV-2 exposed individuals and peaked after the second dose in SARS-CoV-2 naïve PLWH. The presence of adaptive NK cells associated with the magnitude of cellular and humoral responses. These data suggest that features of adaptive NK cells can be effectively engaged to complement and boost vaccine-induced adaptive immunity in potentially more vulnerable groups such as PLWH.

Attenuated humoral responses in HIV after SARS-CoV-2 vaccination linked to B cell defects and altered immune profiles.

We assessed a cohort of people living with human immunodeficiency virus (PLWH) (n = 110) and HIV negative controls (n = 64) after 1, 2 or 3 SARS-CoV-2 vaccine doses. At all timepoints, PLWH had significantly lower neutralizing antibody (nAb) titers than HIV-negative controls. We also observed a delayed development of neutralization in PLWH that was underpinned by a reduced frequency of spike-specific memory B cells (MBCs). Improved neutralization breadth was seen against the Omicron variant (BA.1) after the third vaccine dose in PLWH but lower nAb responses persisted and were associated with global MBC dysfunction. In contrast, SARS-CoV-2 vaccination induced robust T cell responses that cross-recognized variants in PLWH. Strikingly, individuals with low or absent neutralization had detectable functional T cell responses. These PLWH had reduced numbers of circulating T follicular helper cells and an enriched population of CXCR3+CD127+CD8+T cells after two doses of SARS-CoV-2 vaccination.

Blockade of immunosuppressive cytokines restores NK cell antiviral function in chronic hepatitis B virus infection.

NK cells are enriched in the liver, constituting around a third of intrahepatic lymphocytes. We have previously demonstrated that they upregulate the death ligand TRAIL in patients with chronic hepatitis B virus infection (CHB), allowing them to kill hepatocytes bearing TRAIL receptors. In this study we investigated whether, in addition to their pathogenic role, NK cells have antiviral potential in CHB. We characterised NK cell subsets and effector function in 64 patients with CHB compared to 31 healthy controls. We found that, in contrast to their upregulated TRAIL expression and maintenance of cytolytic function, NK cells had a markedly impaired capacity to produce IFN-γ in CHB. This functional dichotomy of NK cells could be recapitulated in vitro by exposure to the immunosuppressive cytokine IL-10, which was induced in patients with active CHB. IL-10 selectively suppressed NK cell IFN-γ production without altering cytotoxicity or death ligand expression. Potent antiviral therapy reduced TRAIL-expressing CD56(bright) NK cells, consistent with the reduction in liver inflammation it induced; however, it was not able to normalise IL-10 levels or the capacity of NK cells to produce the antiviral cytokine IFN-γ. Blockade of IL-10 +/- TGF-ß restored the capacity of NK cells from both the periphery and liver of patients with CHB to produce IFN-γ, thereby enhancing their non-cytolytic antiviral capacity. In conclusion, NK cells may be driven to a state of partial functional tolerance by the immunosuppressive cytokine environment in CHB. Their defective capacity to produce the antiviral cytokine IFN-γ persists in patients on antiviral therapy but can be corrected in vitro by IL-10+/- TGF-ß blockade.

Role of the coinhibitory receptor cytotoxic T lymphocyte antigen-4 on apoptosis-Prone CD8 T cells in persistent hepatitis B virus infection.

UNLABELLED: An excess of coinhibitory signals has been proposed to drive the T-cell exhaustion characteristic of persistent viral infections. In this study we examined the contribution of the coinhibitory receptor cytotoxic T lymphocyte antigen-4 (CTLA-4) to CD8 T cell tolerance in chronic hepatitis B virus (HBV) infection (CHB). CD8 T cells in patients with CHB have an increased propensity to express the coinhibitory receptor CTLA-4 and this correlates with viral load. CTLA-4 is up-regulated on those HBV-specific CD8 T cells with the highest levels of the proapoptotic protein Bim, which we have previously shown mediates their premature attrition; abrogation of CTLA-4-mediated coinhibition can reduce Bim expression. Longitudinal study of CHB patients beginning antiviral therapy reveals that HBV DNA suppression induces transient reconstitution of HBV-specific CD8 T cells but does not reprogram their CTLA-4(hi) Bim(hi) tolerogenic phenotype. Blocking CTLA-4 is able to increase the expansion of interferon gamma (IFN-γ)-producing HBV-specific CD8 T cells in both the peripheral and intrahepatic compartments. The rescue of anti-HBV responses by either CTLA-4 or PD-L1 blockade is nonredundant. CONCLUSION: CTLA-4 is expressed by HBV-specific CD8 T cells with high levels of Bim and helps to drive this proapoptotic phenotype. CTLA-4 blockade could form one arm of a therapeutic approach to modulate the diverse patterns of coregulation of T-cell exhaustion in this heterogeneous disease.

Natural killer cells during acute HIV-1 infection: clues for HIV-1 prevention and therapy.

Despite progress in preexposure prophylaxis, the number of newly diagnosed cases with HIV-1 remains high, highlighting the urgent need for preventive and therapeutic strategies to reduce HIV-1 acquisition and limit disease progression. Early immunological events, occurring during acute infection, are key determinants of the outcome and course of disease. Understanding early immune responses occurring before viral set-point is established, is critical to identify potential targets for prophylactic and therapeutic approaches. Natural killer (NK) cells represent a key cellular component of innate immunity and contribute to the early host defence against HIV-1 infection, modulating the pathogenesis of acute HIV-1 infection (AHI). Emerging studies have identified tools for harnessing NK cell responses and expanding specialized NK subpopulations with adaptive/memory features, paving the way for development of novel HIV-1 therapeutics. This review highlights the knowns and unknowns regarding the role of NK cell subsets in the containment of acute HIV-1 infection, and summarizes recent advances in selectively augmenting NK cell functions through prophylactic and therapeutic interventions.