CD127 expression, exhaustion status and antigen specific proliferation predict sustained virologic response to IFN in HCV/HIV co-infected individuals

Gamma-Delta T-Cell Phenotype and Function in DAA-Treated HIV-HCV Co-Infected and HCV-Mono-Infected Subjects

HIV-HCV co-infected subjects are at risk of liver fibrosis which may be linked to immune imbalances. Direct-acting antivirals (DAAs) represent the mainstay of HCV treatment in co-infected individuals, yet their effects on immune cell populations playing a role in fibrogenesis is unknown. We assessed γδ T-cell phenotype and function, Treg and Th17 frequencies, as well as γ-globulins and B-cell activation in 47 HIV-HCV co-infected and 35 HCV mono-infected individuals prior to and following DAA treatment (SVR12). Γδ T-cell activation decreased in both groups yet persisted at higher levels in the HIV-HCV co-infected subjects. No differences were registered in terms of γδT-cell function. Of note, the Vδ2/Th17 ratio, inversely linked to liver damage, increased significantly in the two groups upon treatment, yet a negative correlation between the Vδ2/Th17 ratio and liver function enzymes was found in the co-infected subjects alone. B-cell activation and γ-globulin levels decreased in both settings, yet B-cell activation remained higher in the HIV-HCV co-infected individuals. In HIV-HCV co-infected and HCV mono-infected participants, the effect of DAA was limited to γδ T- and B-cell activation as well as γ-globulin concentrations and the Vδ2/Th17 ratio, with no changes in γδ T-cell function and Treg frequencies. Importantly, γδ T- and B-cell activation remained at higher levels in the co-infected individuals than in those with HCV mono-infection alone. The persistence of such alterations within these cell subsets may be associated with the risk of hepatic and extrahepatic complications.

Pulmonary Immune Dysregulation and Viral Persistence During HIV Infection

Despite the success of antiretroviral therapy (ART), people living with HIV continue to suffer from high burdens of respiratory infections, lung cancers and chronic lung disease at a higher rate than the general population. The lung mucosa, a previously neglected HIV reservoir site, is of particular importance in this phenomenon. Because ART does not eliminate the virus, residual levels of HIV that remain in deep tissues lead to chronic immune activation and pulmonary inflammatory pathologies. In turn, continuous pulmonary and systemic inflammation cause immune cell exhaustion and pulmonary immune dysregulation, creating a pro-inflammatory environment ideal for HIV reservoir persistence. Moreover, smoking, gut and lung dysbiosis and co-infections further fuel the vicious cycle of residual viral replication which, in turn, contributes to inflammation and immune cell proliferation, further maintaining the HIV reservoir. Herein, we discuss the recent evidence supporting the notion that the lungs serve as an HIV viral reservoir. We will explore how smoking, changes in the microbiome, and common co-infections seen in PLWH contribute to HIV persistence, pulmonary immune dysregulation, and high rates of infectious and non-infectious lung disease among these individuals.

On the impact of hepatitis C virus and heterologous immunity on alloimmune responses following liver transplantation

Virus-induced heterologous immunity is considered a barrier to transplantation tolerance. Yet, hepatitis C (HCV)-infected liver transplant (LT) patients occasionally achieve operational tolerance. We investigated the mechanisms through which HCV infection modulates donor-specific T cell responses following LT and the influence of HCV eradication. We generated T cell lines from HCV-infected LT and non-LT patients before and after HCV eradication and quantified alloreactive responses using cell lines expressing single-HLA class-I antigens in the presence/absence of PD-1/CTLA-4 blockade. HCV-specific CD8+ T cells cross-reacted with allogeneic class-I HLA molecules. HCV-positive LT recipients exhibited a higher proportion of CD8+ T cells coexpressing inhibitory receptors (PD-1/CTLA4) than HCV-negative LT, and their expression correlated with CXCL10 plasma levels. This resulted in decreased antidonor and third-party proliferative responses, which were significantly reversed by HCV eradication. PD-1/CTLA-4 blockade increased the proportion of HCV-specific CD8+ T cells reacting against donor only before viral clearance. In conclusion, HCV infection results in the generation of HCV-specific CD8+ T cells capable of reacting against allogeneic HLA molecules. Following LT, this results in a PD-1/CTLA4-dependent decrease in alloimmune responses. Our findings challenge the notion that heterologous immunity is necessarily detrimental in LT and provide an explanation for the association between HCV eradication and immune-mediated allograft damage.

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

BACKGROUND

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

OBJECTIVES

Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.

METHODS

Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).

RESULTS

Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+_T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+_{T-bet+ CD57+} cells of both patients and healthy donors were CD28_nullCD27_nullCD127_null. Surprisingly, non-senescent CD8+_{T-bet+ CD57-} cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+_T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.

CONCLUSION

Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+_{T-bet+ CD57-} CD28_lowCD27_lowCD127_low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+_T-bet+ cells as a predominant biomarker of this disease.

Future of anti-PD-1/PD-L1 applications: Combinations with other therapeutic regimens

Programmed cell death 1 (PD-1)/programmed cell death 1 ligand (PD-L1) blockade has shown promising effects in cancer immunotherapy. Removing the so-called " brakes" on T cell immune responses by blocking the PD-1/PD-L1 check point should boost anti-tumor immunity and provide durable tumor regression for cancer patients. However, 30%-60% of patients show no response to PD-1/PD-L1 blockade. Thus, it is urgent to explore the underlying resistance mechanisms to improve sensitivity to anti-PD-1/PD-L1 therapy. We propose that the mechanisms promoting resistance mainly include T cell exclusion or exhaustion at the tumor site, immunosuppressive factors in the tumor microenvironment (TME), and a range of tumor-intrinsic factors. This review highlights the power of studying the cellular and molecular mechanisms of resistance to improve the rational design of combination therapeutic strategies that can be translated to the clinic. Here, we briefly discuss the development of PD-1/PD-L1 blockade agents and focus on the current issues and future prospects for potential combinatorial therapeutic strategies that include anti-PD-1/PD-L1 therapy, based upon the available preclinical and clinical data.

Coinhibitory Receptor Expression and Immune Checkpoint Blockade: Maintaining a Balance in CD8+ T Cell Responses to Chronic Viral Infections and Cancer

In cancer and chronic viral infections, T cells are exposed to persistent antigen stimulation. This results in expression of multiple inhibitory receptors also called “immune checkpoints” by T cells. Although these inhibitory receptors under normal conditions maintain self-tolerance and prevent immunopathology, their sustained expression deteriorates T cell function: a phenomenon called exhaustion. Recent advances in cancer immunotherapy involve blockade of cytotoxic T lymphocyte antigen-4 and programmed cell death 1 in order to reverse T cell exhaustion and reinvigorate immunity, which has translated to dramatic clinical remission in many cases of metastatic melanoma and lung cancer. With the paucity of therapeutic vaccines against chronic infections such as HIV, HPV, hepatitis B, and hepatitis C, such adjunct checkpoint blockade strategies are required including the blockade of other inhibitory receptors such as T cell immunoreceptor with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif domains, T cell Ig and mucin-domain containing-3, lymphocyte activation gene 3, and V-domain Ig-containing suppressor of T cell activation. The nature of different chronic viral infections and cancers is likely to influence the level, composition, and pattern of inhibitory receptors expressed by responding T cells. This will have implications for checkpoint antibody blockade strategies employed for treating tumors and chronic viral infections. Here, we review recent advances that provide a clearer insight into the role of coinhibitory receptor expression in T cell exhaustion and reveal novel antibody-blockade therapeutic targets for chronic viral infections and cancer. Understanding the mechanism of T cell exhaustion in response to chronic virus infections and cancer as well as the nature of restored T cell responses will contribute to further improvement of immune checkpoint blockade strategies.

Ageing and latent CMV infection impact on maturation, differentiation and exhaustion profiles of T-cell receptor gammadelta T-cells

Ageing is a broad cellular process, largely affecting the immune system, especially T-lymphocytes. Additionally to immunosenescence alone, cytomegalovirus (CMV) infection is thought to have major impacts on T-cell subset composition and exhaustion. These impacts have been studied extensively in TCRαβ+ T-cells, with reduction in naive, increase in effector (memory) subsets and shifts in CD4/CD8-ratios, in conjunction with morbidity and mortality in elderly. Effects of both ageing and CMV on the TCRγδ+ T-cell compartment remain largely elusive. In the current study we investigated Vγ- and Vδ-usage, maturation, differentiation and exhaustion marker profiles of both CD4 and CD8 double-negative (DN) and CD8+TCRγδ+ T-cells in 157 individuals, age range 20–95. We observed a progressive decrease in absolute numbers of total TCRγδ+ T-cells in blood, affecting the predominant Vγ9/Vδ2 population. Aged TCRγδ+ T-cells appeared to shift from naive to more (late-stage) effector phenotypes, which appeared more prominent in case of persistent CMV infections. In addition, we found effects of both ageing and CMV on the absolute counts of exhausted TCRγδ+ T-cells. Collectively, our data show a clear impact of ageing and CMV persistence on DN and CD8+TCRγδ+ T-cells, similar to what has been reported in CD8+TCRαβ+ T-cells, indicating that they undergo similar ageing processes.

CD127 Expression in Naive and Memory T Cells in HIV Patients Who Have Undergone Long-Term HAART

OBJECTIVE

To evaluate cluster of differentiation (CD)127 expression in T cells of patients with HIV-1 and the relationship of CD127 expression with disease progression.

METHODS

We divided 139 patients infected with human immunodeficiency virus type 1 (HIV-1) who had undergone highly active antiretroviral therapy (HAART) into 3 groups: patients with poor recovery (CD4⁺T < 350/μ;L, patients with general recovery (CD4⁺T =  350 - ∼600/μL) and patients with good recovery (CD4⁺T > 600/μL). Counts and percentages of naïve (CD45RA⁺) and memory (CD45RO⁺) T cells and CD127 expression were determined using flow cytometry.

RESULTS

CD4⁺CD45RO⁺, CD4⁺CD45RA⁺, CD4⁺ CD45RO⁺ CD127⁺, and CD4⁺CD45RA⁺CD127⁺T-cell counts in patients with good recovery were higher than in patients with poor recovery and those with general recovery patients (P <.05). Percentages of CD45RO⁺ were increased, and percentages of CD45RA⁺ and CD127 in T cells were decreased in patients with poor and general recovery (P <.05). CD127 values were positively correlated with CD4⁺T-cell counts and percentages of CD45RA⁺ subsets (P <.05).

CONCLUSION

CD127 expression in T cells is decreased in patients with HIV-1 and is related to recovery of CD4⁺T-cell counts and to naïve subsets.

Specific CD8+ T cell response immunotherapy for hepatocellular carcinoma and viral hepatitis

Hepatocellular carcinoma (HCC), chronic hepatitis B (CHB) and chronic hepatitis C (CHC) are characterized by exhaustion of the specific CD8⁺ T cell response. This process involves enhancement of negative co-stimulatory molecules, such as programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte antigen-4 (CTLA-4), 2B4, Tim-3, CD160 and LAG-3, which is linked to intrahepatic overexpression of some of the cognate ligands, such as PD-L1, on antigen presenting cells and thereby favouring a tolerogenic environment. Therapies that disrupt these negative signalling mechanisms represent promising therapeutic tools with the potential to restore reactivity of the specific CD8⁺ T cell response. In this review we discuss the impressive in vitro and in vivo results that have been recently achieved in HCC, CHB and CHC by blocking these negative receptors with monoclonal antibodies against these immune checkpoint modulators. The article mainly focuses on the role of CTLA-4 and PD-1 blocking monoclonal antibodies, the first ones to have reached clinical practice. The humanized monoclonal antibodies against CTLA-4 (tremelimumab and ipilimumab) and PD-1 (nivolumab and pembrolizumab) have yielded good results in testing of HCC and chronic viral hepatitis patients. Trelimumab, in particular, has shown a significant increase in the time to progression in HCC, while nivolumab has shown a remarkable effect on hepatitis C viral load reduction. The research on the role of ipilimumab, nivolumab and pembrolizumab on HCC is currently underway.

HCV Specific IL-21 Producing T Cells but Not IL-17A Producing T Cells Are Associated with HCV Viral Control in HIV/HCV Coinfection

BACKGROUND

Decreased hepatitis C virus (HCV) clearance, faster cirrhosis progression and higher HCV RNA levels are associated with Human Immunodeficiency virus (HIV) coinfection. The CD4+ T helper cytokines interleukin (IL)-21 and IL-17A are associated with virus control and inflammation, respectively, both important in HCV and HIV disease progression. Here, we examined how antigen-specific production of these cytokines during HCV mono and HIV/HCV coinfection was associated with HCV virus control.

METHODS

We measured HCV-specific IL-21 and IL-17A production by transwell cytokine secretion assay in PBMCs from monoinfected and coinfected individuals. Viral control was determined by plasma HCV RNA levels.

RESULTS

In acutely infected individuals, those able to establish transient/complete HCV viral control tended to have stronger HCV-specific IL-21-production than non-controllers. HCV-specific IL-21 production also correlated with HCV viral decline in acute infection. Significantly stronger HCV-specific IL-21 production was detected in HAART-treated coinfected individuals. HCV-specific IL-17A production was not associated with lower plasma HCV RNA levels in acute or chronic HCV infection and responses were stronger in HIV coinfection. HCV-specific IL-21/ IL-17A responses did not correlate with microbial translocation or fibrosis. Exogenous IL-21 treatment of HCV-specific CD8+ T cells from monoinfected individuals enhanced their function although CD8+ T cells from coinfected individuals were somewhat refractory to the effects of IL-21.

CONCLUSIONS

These data show that HCV-specific IL-21 and IL-17A-producing T cells are induced in HIV/HCV coinfection. In early HIV/HCV coinfection, IL-21 may contribute to viral control, and may represent a novel tool to enhance acute HCV clearance in HIV/HCV coinfected individuals.

T-cell homeostasis in chronic HCV-infected patients treated with interferon and ribavirin or an interferon-free regimen

Direct-acting antiviral has replaced pegylated interferon-α and ribavirin-based treatment in the treatment of chronic hepatitis C virus (HCV) infection. While interferon-α is immune modulating and causes lymphopenia, interferon-free regimens seem to be well-tolerated. This study aimed to compare T-cell homeostasis before, during, and after HCV treatment with or without interferon-α in patients with chronic HCV infection. A total of 20 patients with chronic HCV infection were treated with pegylated interferon-α and ribavirin, and six patients were treated with an interferon-free regimen. All patients were treated for a minimum of 12 weeks. Interferon-α treatment caused an increase in the density of the receptor for IL-7 (IL-7Rα) during treatment, while interferon-free regimens caused a decrease in IL-7Rα density. After a sustained viral response, proportions of IL-7Rα+ T cells and IL-7Rα density decreased compared to prior treatment values. Finally, a proportion of CD8+ effector memory was lower while proportion of apoptotic T cells was higher after sustained virologic response compared to prior treatment. Despite lymphopenia during interferon, alterations in T-cell homeostasis during treatment were relatively similar in patients receiving interferon-based treatment and in patients receiving interferon-free treatment, and alterations during and after treatment seem to illustrate a reduced need for high levels of T cells aimed at controlling infection.

Association between IL7RA polymorphisms and the successful therapy against HCV in HIV/HCV-coinfected patients

Interleukin-7 (IL-7) is a critical factor in maintaining or inducing effective antiviral CD4+ and CD8+ T-cell responses. The aim of this study was to examine the association of interleukin-7 receptor-α (IL7RA) polymorphisms with a sustained virologic response (SVR) after hepatitis C virus (HCV) therapy with pegylated interferon-alpha plus ribavirin (pegIFNα/ribavirin) in 177 human immunodeficiency virus (HIV)/HCV-coinfected patients. We performed a retrospective study in 177 naïve patients who started HCV treatment. The IL7RA rs6897932, rs987106, and rs3194051 polymorphisms were genotyped by the GoldenGate® assay. An SVR was defined as undetectable HCV viral load through 24 weeks after the end of HCV treatment. The highest SVR rate was found in patients with the rs6897932 CC (p = 0.029) and rs3194051 GG (p = 0.002) genotypes, and HCV genotypes 2/3 (GT2/3) infected patients with the rs987106 AA genotype (p = 0.048). Additionally, carriers of the rs3194051 GG genotype had a higher likelihood of achieving an SVR [adjusted odds ratio (aOR) = 5.32; 95 % confidence interval (CI) = 1.07-26.94; p = 0.040] than patients with the rs3194051 AA/AG genotype, while rs6897932 CC (aOR = 0.63; p = 0.205) and rs987106 AA (aOR = 0.60; p = 0.213) were not significant. Moreover, three major haplotypes were found: 46.6 % for CTA, 32.4 % for CAG, and 20.7 % for TAA haplotypes. Patients infected with GT2/3 and carriers of the CTA haplotype had lower odds of achieving an SVR (aOR = 0.08; p = 0.004) and the CAG haplotype (favorable alleles) had higher odds of achieving an SVR than other haplotypes (aOR = 21.96; p < 0.001). IL7RA polymorphisms seem to play a significant role in the virological response to pegIFNα/ribavirin therapy in HIV/HCV-coinfected patients, in particular among patients infected with HCV GT2/3.