DNAM-1 and the TIGIT/PVRIG/TACTILE Axis: Novel Immune Checkpoints for Natural Killer Cell-Based Cancer Immunotherapy

Natural killer (NK) cells are lymphocytes of the innate immune response characterized by their role in the destruction of tumor cells. Activation of NK cells depend on a fine balance between activating and inhibitory signals mediated by different receptors. In recent years, a family of paired receptors that interact with ligands of the Nectin/Nectin-like (Necl) family has attracted great interest. Two of these ligands, Necl-5 (usually termed CD155 or PVR) and Nectin-2 (CD112), frequently expressed on different types of tumor cells, are recognized by a group of receptors expressed on T and NK cells that exert opposite functions after interacting with their ligands. These receptors include DNAM-1 (CD226), TIGIT, TACTILE (CD96) and the recently described PVRIG. Whereas activation through DNAM-1 after recognition of CD155 or CD112 enhances NK cell-mediated cytotoxicity against a wide range of tumor cells, TIGIT recognition of these ligands exerts an inhibitory effect on NK cells by diminishing IFN-γ production, as well as NK cell-mediated cytotoxicity. PVRIG has also been identified as an inhibitory receptor that recognizes CD112 but not CD155. However, little is known about the role of TACTILE as modulator of immune responses in humans. TACTILE control of tumor growth and metastases has been reported in murine models, and it has been suggested that it negatively regulates the anti-tumor functions mediated by DNAM-1. In NK cells from patients with solid cancer and leukemia, it has been observed a decreased expression of DNAM-1 that may shift the balance in favor to the inhibitory receptors TIGIT or PVRIG, further contributing to the diminished NK cell-mediated cytotoxic capacity observed in these patients. Analysis of DNAM-1, TIGIT, TACTILE and PVRIG on human NK cells from solid cancer or leukemia patients will clarify the role of these receptors in cancer surveillance. Overall, it can be speculated that in cancer patients the TIGIT/PVRIG pathways are upregulated and represent novel targets for checkpoint blockade immunotherapy

Characterization of the DNAM-1, TIGIT and TACTILE Axis on Circulating NK, NKT-Like and T Cell Subsets in Patients with Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) remains a major clinical challenge due to poor overall survival, which is even more dramatic in elderly patients. TIGIT, an inhibitory receptor that interacts with CD155 and CD112 molecules, is considered as a checkpoint in T and NK cell activation. This receptor shares ligands with the co-stimulatory receptor DNAM-1 and with TACTILE. The aim of this work was to analyze the expression of DNAM-1, TIGIT and TACTILE in NK cells and T cell subsets in AML patients. Methods: We have studied 36 patients at the time of diagnosis of AML and 20 healthy volunteers. The expression of DNAM-1, TIGIT and TACTILE in NK cells and T cells, according to the expression of CD3 and CD56, was performed by flow cytometry. Results: NK cells, CD56− T cells and CD56+ T (NKT-like) cells from AML patients presented a reduced expression of DNAM-1 compared with healthy volunteers. An increased expression of TIGIT was observed in mainstream CD56− T cells. No differences were observed in the expression of TACTILE. Simplified presentation of incredibly complex evaluations (SPICE) analysis of the co-expression of DNAM-1, TIGIT and TACTILE showed an increase in NK and T cells lacking DNAM-1 and co-expressing TIGIT and TACTILE. Low percentages of DNAM-1−TIGIT+TACTILE+ NK cells and DNAM-1− TIGIT+TACTILE+ CD56− T cells were associated with a better survival of AML patients. Conclusions: The expression of DNAM-1 is reduced in NK cells and in CD4+ and CD8+ T cells from AML patients compared with those from healthy volunteers. An increased percentage of NK and T cells lacking DNAM-1 and co-expressing TIGIT and TACTILE is associated with patient survival, supporting the role of TIGIT as a novel candidate for checkpoint blockade

Prognosis of Paradoxical Low-Flow Low-Gradient Aortic Stenosis : A Severe, Non-critical Form, With Surgical Treatment Benefits

To determine the risk of mortality and need for aortic valve replacement (AVR) in patients with low-flow low-gradient (LFLG) aortic stenosis (AS). A longitudinal multicentre study including consecutive patients with severe AS (aortic valve area [AVA] 35 ml/m 2) and LFLG (mean gradient < 40 mmHg, SVi ≤ 35 ml/m 2). Of 1,391 patients, 147 (10.5%) had LFLG, 752 (54.1%) HG, and 492 (35.4%) NFLG. Echocardiographic parameters of the LFLG group showed similar AVA to the HG group but with less severity in the dimensionless index, calcification, and hypertrophy. The HG group required AVR earlier than NFLG (p < 0.001) and LFLG (p < 0.001), with no differences between LFLG and NFLG groups (p = 0.358). Overall mortality was 27.7% (CI 95% 25.3-30.1) with no differences among groups (p = 0.319). The impact of AVR in terms of overall mortality reduction was observed the most in patients with HG (hazard ratio [ HR ]: 0.17; 95% CI : 0.12-0.23; p < 0.001), followed by patients with LFLG (HR : 0.25; 95% CI : 0.13-0.49; p < 0.001), and finally patients with NFLG (HR : 0.29; 95% CI : 0.20-0.44; p < 0.001), with a risk reduction of 84, 75, and 71%, respectively. Paradoxical LFLG AS affects 10.5% of severe AS, and has a lower need for AVR than the HG group and similar to the NFLG group, with no differences in mortality. AVR had a lower impact on LFLG AS compared with HG AS. Therefore, the findings of the present study showed LFLG AS to have an intermediate clinical risk profile betwee the HG and NFHG group

Clinical Risk Prediction in Patients With Left Ventricular Myocardial Noncompaction

Left ventricular noncompaction (LVNC) is a heterogeneous entity with uncertain prognosis. This study sought to develop and validate a prediction model of major adverse cardiovascular events (MACE) and to identify LVNC cases without events during long-term follow-up. This is a retrospective longitudinal multicenter cohort study of consecutive patients fulfilling LVNC criteria by echocardiography or cardiovascular magnetic resonance. MACE were defined as heart failure (HF), ventricular arrhythmias (VAs), systemic embolisms, or all-cause mortality. A total of 585 patients were included (45 ± 20 years of age, 57% male). LV ejection fraction (LVEF) was 48% ± 17%, and 18% presented late gadolinium enhancement (LGE). After a median follow-up of 5.1 years, MACE occurred in 223 (38%) patients: HF in 110 (19%), VAs in 87 (15%), systemic embolisms in 18 (3%), and 34 (6%) died. LVEF was the main variable independently associated with MACE (P 35% (P < 0.05). A prediction model of MACE was developed using Cox regression, composed by age, sex, electrocardiography, cardiovascular risk factors, LVEF, and family aggregation. C-index was 0.72 (95% confidence interval: 0.67-0.75) in the derivation cohort and 0.72 (95% confidence interval: 0.71-0.73) in an external validation cohort. Patients with no electrocardiogram abnormalities, LVEF ≥50%, no LGE, and negative family screening presented no MACE at follow-up. LVNC is associated with an increased risk of heart failure and ventricular arrhythmias. LVEF is the variable most strongly associated with MACE; however, LGE confers additional risk in patients without severe systolic dysfunction. A risk prediction model is developed and validated to guide management.The project was partially funded by a grant from the Catalan Society of Cardiology (Barcelona, Spain). Hospital Universitario Virgen de la Arrixaca (Murcia, Spain) was supported by a grant from the Foundation Marató TV3 (218/C/2015) (Barcelona, Spain). Hospital Universitario y Politécnico La Fe (Valencia, Spain) was partially supported by Fondo Europeo de Desarrollo Regional (“Unión Europea, Una forma de hacer Europa”) (Madrid, Spain) and the Instituto de Salud Carlos III (La Fe Biobank PT17/0015/ 0043) (Madrid, Spain). Dr Guala was supported by funding from the Spanish Ministry of Science, Innovation and Universities (IJC2018-037349-I) (Madrid, Spain). Dr La Mura was supported by a research grant from the Cardiopath PhD program (Naples, Italy). Prof de la Pompa was supported by grants PID2019-104776RB-I00 and CB16/11/00399 (CIBER CV) from the Spanish Ministry of Science, Innovation and Universities. Dr Bayes-Genis was supported by grants from CIBER Cardiovascular (CB16/11/00403 and 16/11/00420) (Madrid, Spain) and AdvanceCat 2014-2020 (Barcelona, Spain); and has received advisory board and lecture fees from Novartis, Boehringer Ingelheim, Vifor, Roche Diagnostics, and Critical Diagnostics. Dr Pontone has received speaker honorarium and/or institutional research grants from GE Healthcare, Bracco, Boehringer Ingelheim, and HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.S