PD-1-expressing tumor-infiltrating T cells are a favorable prognostic biomarker in HPV-associated head and neck cancer

Head and neck cancers positive for human papillomavirus (HPV) have a more favorable clinical outcome than HPV-negative cancers, but it is unknown why this is the case. We hypothesized that prognosis was affected by intrinsic features of HPV-infected tumor cells or differences in host immune response. In this study, we focused on a comparison of regulatory Foxp3(+) T cells and programmed death-1 (PD-1)(+) T cells in the microenvironment of tumors that were positive or negative for HPV, in two groups that were matched for various clinical and biologic parameters. HPV-positive head and neck cancers were more heavily infiltrated by regulatory T cells and PD-1(+) T cells and the levels of PD-1(+) cells were positively correlated with a favorable clinical outcome. In explaining this paradoxical result, we showed that these PD-1(+) T cells expressed activation markers and were functional after blockade of the PD-1-PD-L1 axis in vitro. Approximately 50% of PD-1(+) tumor-infiltrating T cells lacked Tim-3 expression and may indeed represent activated T cells. In mice, administration of a cancer vaccine increased PD-1 on T cells with concomitant tumor regression. In this setting, PD-1 blockade synergized with vaccine in eliciting antitumor efficacy. Our findings prompt a need to revisit the significance of PD-1-infiltrating T cells in cancer, where we suggest that PD-1 detection may reflect a previous immune response against tumors that might be reactivated by PD-1/PD-L1 blockade.

CD160 and PD-1 co-expression on HIV-specific CD8 T cells defines a subset with advanced dysfunction

Chronic viral infections lead to persistent CD8 T cell activation and functional exhaustion. Expression of programmed cell death-1 (PD-1) has been associated to CD8 T cell dysfunction in HIV infection. Herein we report that another negative regulator of T cell activation, CD160, was also upregulated on HIV-specific CD8 T lymphocytes mostly during the chronic phase of infection. CD8 T cells that expressed CD160 or PD-1 were still functional whereas co-expression of CD160 and PD-1 on CD8 T cells defined a novel subset with all the characteristics of functionally exhausted T cells. Blocking the interaction of CD160 with HVEM, its natural ligand, increased HIV-specific CD8 T cell proliferation and cytokine production. Transcriptional profiling showed that CD160⁻PD-1⁺CD8 T cells encompassed a subset of CD8⁺ T cells with activated transcriptional programs, while CD160⁺PD-1⁺ T cells encompassed primarily CD8⁺ T cells with an exhausted phenotype. The transcriptional profile of CD160⁺PD-1⁺ T cells showed the downregulation of the NFκB transcriptional node and the upregulation of several inhibitors of T cell survival and function. Overall, we show that CD160 and PD-1 expressing subsets allow differentiating between activated and exhausted CD8 T cells further reinforcing the notion that restoration of function will require multipronged approaches that target several negative regulators.

HIV infection is widely known to cause generalized immune activation and immune exhaustion ultimately leading to HIV disease progression. Several studies have suggested over the years that the accumulation of inhibitory signalling proteins on the surface of responding cells is linked to immune exhaustion in HIV. It has become paramount to distinguish functionally exhausted CD8 T cells from activated HIV-specific CD8 T cells because both cell types have different fates. Using specific cell surface markers, we were able to identify these different cell types and show that HIV-infected patients accumulate dysfunctional CD8 T cells over time. Importantly, we show that this dysfunction is reversible.

Characteristics and outcomes of initial virologic suppressors during analytic treatment interruption in a therapeutic HIV-1 gag vaccine trial

Background

In the placebo-controlled trial ACTG A5197, a trend favoring viral suppression was seen in the HIV-1-infected subjects who received a recombinant Ad5 HIV-1 gag vaccine.

Objective

To identify individuals with initial viral suppression (plasma HIV-1 RNA set point <3.0 log₁₀ copies/ml) during the analytic treatment interruption (ATI) and evaluate the durability and correlates of virologic control and characteristics of HIV sequence evolution.

Methods

HIV-1 gag and pol RNA were amplified and sequenced from plasma obtained during the ATI. Immune responses were measured by flow cytometric analysis and intracellular cytokine expression assays. Characteristics of those with and without initial viral suppression were compared using the Wilcoxon rank sum and Fisher's exact tests.

Results

Eleven out of 104 participants (10.6%) were classified as initial virologic suppressors, nine of whom had received the vaccine. Initial virologic suppressors had significantly less CD4+ cell decline by ATI week 16 as compared to non-suppressors (median 7 CD4+ cell gain vs. 247 CD4+ cell loss, P = 0.04). However, of the ten initial virologic suppressors with a pVL at ATI week 49, only three maintained pVL <3.0 log₁₀ copies/ml. HIV-1 Gag-specific CD4+ interferon-γ responses were not associated with initial virologic suppression and no evidence of vaccine-driven HIV sequence evolution was detected. Participants with initial virologic suppression were found to have a lower percentage of CD4+ CTLA-4+ cells prior to treatment interruption, but a greater proportion of HIV-1 Gag-reactive CD4+ TNF-α+ cells expressing either CTLA-4 or PD-1.

Conclusions

Among individuals participating in a rAd5 therapeutic HIV-1 gag vaccine trial, initial viral suppression was found in a subset of patients, but this response was not sustained. The association between CTLA-4 and PD-1 expression on CD4+ T cells and virologic outcome warrants further study in trials of other therapeutic vaccines in development.

Trial Registration

ClinicalTrials.gov NCT00080106

Aberrant expression of the negative costimulator PD-1 on T cells in granulomatosis with polyangiitis

OBJECTIVE

Persistent T-cell activation is frequently observed in granulomatosis with polyangiitis (GPA, formerly known as Wegener's granulomatosis). T-cell activation is usually balanced by negative costimulatory molecules. The negative costimulator programmed death receptor-1 (PD-1) and its relevance to T-cell immunity have not been studied so far in GPA. Thus it is the aim of the study to characterize the role of PD-1 in GPA.

METHODS

Thirty-two patients suffering from GPA and 19 age-matched healthy controls (HCs) were enrolled. T-lymphocyte subsets from peripheral blood were analysed by flow cytometry for the expression of PD-1. The frequency of memory T cells and T cells producing pro-inflammatory cytokines was determined. Renal biopsies from GPA patients were stained for CD3 and PD-1.

RESULTS

PD-1 expression was increased on T-helper cells (Th cells) from GPA patients as compared with HCs. In addition, parameters of persistent T-cell activation and production of pro-inflammatory cytokines were positively associated with numbers of PD-1(+) Th cells in patients but not in HCs. Latent infection with CMV seemed to enhance PD-1 expression on CD4(+) and CD4(+)CD25(-) T cells. Interestingly, expression of PD-1 on CD4(+)CD25(+)T cells was inversely correlated with relapse rate. Importantly, lesional T cells were mostly lacking PD-1.

CONCLUSIONS

The expression of the negative costimulator PD-1 is altered in GPA and might counterbalance persistent T-cell activation.