Natural killer (NK) cells mount an immune response against hepatitis C virus (HCV) infection and can be activated by several cytokines, including interleukin-2 (IL-2), IL-15, and interferon-alpha (IFN-α). By exploiting the Huh7.5 hepatoma cell line infected with the HCV JFH1 genome, we provide novel insights into the antiviral effector functions of human primary NK cells after cytokine stimulation. NK cells activated with IFN-α (IFNα-NKs) had enhanced contact-dependent and -independent responses as compared with NK cells activated with IL-2/IL-15 (IL2/IL15-NKs) and could inhibit HCV replication both in vitro and in vivo. Importantly, IFN-α, but not IL-2/IL-15, protected NK cells from the functional inhibition exerted by HCV. By performing flow cytometry, multiplex cytokine profiling, and mass-spectrometry-based proteomics, we discovered that IFNα-NKs secreted high levels of galectin-9 and interferon-gamma (IFN-γ), and by conducting neutralization assays, we confirmed the major role of these molecules in HCV suppression. We speculated that galectin-9 might act extracellularly to inhibit HCV binding to host cells and downstream infection. In silico approaches predicted the binding of HCV envelope protein E2 to galectin-9 carbohydrate-recognition domains, and co-immunoprecipitation assays confirmed physical interaction. IFN-γ, on the other hand, triggered the intracellular expressions of two antiviral gate-keepers in target cells, namely, myxovirus-1 (MX1) and interferon-induced protein with tetratricopeptide repeats 1 (IFIT1). Collectively, our data add more complexity to the antiviral innate response mediated by NK cells and highlight galectin-9 as a key molecule that might be exploited to neutralize productive viral infection.

Significance: In the present study, we provide evidence of a cellular mechanism of breach of tolerance in an in vivo model of spontaneous autoimmune thyroiditis (AIT). We observe that self-antigen (Ag) specific T_regcirculate in all lymphatic tissues except for the lymph nodes (LNs) draining the thyroid, which represents the site of inflammation. By contrast, cognate effector T cells accumulate in the draining LNs and thyroid. The absence of T_regunleashes cognate T_eff, which promote tissue destruction. We demonstrate that the organ-restricted disappearance of T_regis driven by the self-Ag, aberrantly expressed in a highly inflammatory environment, by a mechanism of activation-induced cell death.

The cytotoxic activity of T cells and Natural Killer cells is usually measured with the chromium release assay (CRA), which involves the use of 51Chromium (⁵¹Cr), a radioactive substance dangerous to the operator and expensive to handle and dismiss. The accuracy of the measurements depends on how well the target cells incorporate ⁵¹Cr during labelling which, in turn, depends on cellular division. Due to bystander metabolism, the target cells spontaneously release ⁵¹Cr, producing a high background noise. Alternative radioactive-free methods have been developed. Here, we compare a bioluminescence (BLI)-based and a carboxyfluorescein succinimidyl ester (CFSE)-based cytotoxicity assay to the standard radioactive CRA. In the first assay, the target cells stably express the enzyme luciferase, and vitality is measured by photon emission upon the addition of the substrate d-luciferin. In the second one, the target cells are labelled with CFSE, and the signal is detected by Flow Cytometry. We used these two protocols to measure cytotoxicity induced by treatment with NK cells. The cytotoxicity of NK cells was determined by adding increasing doses of human NK cells. The results obtained with the BLI method were consistent with those obtained with the CRA- or CFSE-based assays 4 hours after adding the NK cells. Most importantly, with the BLI assay, the kinetic of NK cells’ killing was thoroughly traced with multiple time point measurements, in contrast with the single time point measurement the other two methods allow, which unveiled additional information on NK cell killing pathways.

Chimeric antigen receptor (CAR)-modified natural killer (NK) cells represent a promising immunotherapeutic approach for the treatment of oncological malignancies such as hepatocellular carcinoma (HCC). In this work, we have engineered primary human NK cells, re-directing them so they can specifically recognize Glypican-3 (GPC3), an immunotherapeutic target for HCC. In previous studies, we have demonstrated that IFN-α significantly enhances NK cells’ anti-tumor and anti-viral cytotoxicity. Fourth-generation self-inactivating lentiviral vectors were used to deliver a transgenic expression of IFN-α or its co-expression with IL-15 (which induces NK cells expansion, survival, and function), aiming to enhance CAR-GPC3 NK cells’ anti-tumor response against HCC. We optimized a protocol for efficient transduction of primary NK cells, demonstrating that CAR expression is maintained at high levels over time. Exposure of HCC ectopically expressing GPC3+ to CAR-GPC3-IL15 and CAR-GPC3-IL15-IFNα NK cells demonstrated significant in vitro cytotoxicity and cytokine production, dependent on GPC3 expression. To prevent undesired side effects of CAR-NK cell immunotherapy, co-delivery with a suicide gene is advised as a safety measure. Thus, a truncated epidermal growth factor receptor (tEGFR) was co-delivered with the anti-GPC3 CAR, which efficiently promoted the suicide of the CAR-NK used in this work. Our study demonstrates the efficacy of re-directed CAR-GPC3 primary NK cells, encouraging further preclinical and clinical translation studies and strengthening the potential of these cells as a novel treatment option for patients with HCC.

Extracorporeal membrane oxygenation (ECMO) is a vital intervention for patients with severe respiratory failure, particularly in unresponsive acute respiratory distress syndrome (ARDS) cases. However, patient selection for ECMO remains a significant challenge. This study aims to identify novel immune-based biomarkers to improve eligibility assessment and predict outcomes in critically ill COVID-19 patients undergoing ECMO. This monocentric observational retrospective cohort study included 80 patients with severe COVID-19-related pneumonia who required ECMO support due to unresponsive ARDS. The patients were admitted to the intensive care unit (ICU) of IRCCS-ISMETT Hospital between September 2020 and April 2021, before the availability of COVID-19 vaccines. All patients were infected with the original SARS-CoV-2 Wuhan strain. Using machine learning approaches, the study analyzed clinical and laboratory data, cytokine levels, RNA sequencing (RNA-seq), and immune cell profiles collected within two days of hospitalization. The analysis identified a 5.56-fold increased mortality risk in patients presenting with a combination of immune factors: a T cell exhaustion profile, low interferon-alpha (IFNα) levels, and high calprotectin levels. These immune markers were strongly associated with poorer outcomes in patients undergoing ECMO. Our findings highlight the critical role of immune profiling in ECMO patient selection and outcome prediction. Incorporating immune-based biomarkers into clinical assessments may enhance the evaluation of ECMO eligibility and guide treatment decisions, ultimately improving patient outcomes.

Background: Ischemia/reperfusion injury (IRI), acute rejection (AR), and delayed graft function (DGF) might occur as major complications following kidney transplantation. Thus, the identification of biomarkers for the IRI, AR, and/or DGF development becomes crucial as it may help to guide post-transplant management. Natural killer (NK) cells, hepatic interstitial T-lymphocytes (T-Li), and NK-T cells are crucial in both innate and adaptive immunity after abdominal solid organ transplantation. Hence, the aim of this study was to evaluate the impact of the immune system after graft reperfusion during KT in adults in order to identify predictive biomarkers. Methods: The NK, T-Li, and NK-T phenotypes and concentrations were retrospectively analyzed in a consecutive series of liver perfusates obtained after organ procurement flushing the abdominal cavity recovered from deceased brain donors (DBDs). Their percentage was compared with the renal transplant recipients’ characteristics with kidneys taken from the same DCDs. The hepatic perfusate cells were purified by density gradient centrifugation. Flow cytometric investigation was used to determine their phenotype with the following immunological markers in order to determine the relative percentage of T-Li, NK-T, and NK cells: CD3, CD4, CD8, and CD56. Results: 42 DBDs’ liver perfusates were analyzed. The related clinical outcomes of kidney transplant recipients from 2010 to 2020 performed at our Institute were evaluated. Time in days of delayed functional recovery of transplanted kidneys (DGF) (p = 0.02) and the onset of secondary infection from a cytomegalovirus (p = 0.03) were significantly associated with the T-Li percentage. An increased relative risk (HR) of organ survival was significantly associated with the percent cell concentration of T-Li and time to DGF, on COX analysis, were (HR = 1.038, p = 0.04; and HR = 1.029, p = 0.01, respectively). None relevant clinical outcomes in kidney transplant patients were associated with the specificity of the NK and NK-T cell proportions. Conclusions: A new potential role of T-Li cells was detected in the context of hepatic perfusate from DBDs. It could detect potential impacts in organ allocation, surgical procuring techniques, and in the analysis of IRI pathophysiological events.