👤 Alina D Peshkova

Leukocyte-platelet aggregates (LPAs) play a crucial role in the pathogenesis of inflammatory diseases, linking pathological immune responses with thrombosis.The levels of LPAs, their composition, and cellular reactivity were determined in patients with distinct inflammatory conditions, namely coronavirus disease 2019 (COVID-19), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE), compared with healthy controls. Flow cytometry was used to identify cell types and measure LPA levels in the blood. The ability of platelets, neutrophils, and monocytes to form additional LPAs in response to hyperstimulation with phorbol-12-myristate-13-acetate (PMA) was assessed. Coaggregation of isolated neutrophils and platelets in vitro was visualized using scanning electron microscopy. Blood tests included coagulation, hematology, biochemistry, and immunology.LPA levels were significantly higher in all patient groups compared with controls, with variations in the composition: neutrophil-platelet aggregates predominated in the COVID-19 patients, whereas monocyte-platelet aggregates prevailed in the blood of RA and SLE patients. Platelet-to-leukocyte ratios within aggregates varied in a broad range with a substantial prevalence of platelets over leukocytes. Morphological analysis revealed coaggregation of platelets with neutrophils, including relatively large homotypic platelet aggregates associated with one or two neutrophils. In PMA-treated pathological blood samples from COVID-19, RA, and SLE patients, the ability to form additional LPAs over the patients' baseline level was reduced compared with normal blood samples, indicating impaired reactivity (exhaustion) of neutrophils and monocytes in all patient groups.This study highlights distinct changes in the number and composition of LPAs in inflammatory diseases of various etiologies associated with altered functionality of the innate immune cells. Show less

Although inflammatory mechanisms driving hepatocellular carcinoma (HCC) have been proposed, the regulators of anticancer immunity in HCC remain poorly understood. We found that IL27 receptor (IL27R) signaling promotes HCC development in vivo. High IL27EBI3 cytokine or IL27RA expression correlated with poor prognosis for patients with HCC. Loss of IL27R suppressed HCC in vivo in two different models of hepatocarcinogenesis. Mechanistically, IL27R sig-naling within the tumor microenvironment restrains the cytotoxicity of innate cytotoxic lymphocytes. IL27R ablation enhanced their accumulation and activation, whereas depletion or functional impairment of innate cytotoxic cells abrogated the effect of IL27R disruption. Pharmacologic neutralization of IL27 signaling increased infiltration of innate cytotoxic lymphocytes with upregulated cytotoxic molecules and reduced HCC development. Our data reveal an unexpected role of IL27R signaling as an immunologic checkpoint regulating innate cytotoxic lymphocytes and promoting HCC of different etiologies, thus indicating a therapeutic potential for IL27 pathway blockade in HCC. HCC, the most common form of liver cancer, is characterized by a poor survival rate and limited treatment options. The discovery of a novel IL27-dependent mechanism controlling anticancer cytotoxic immune response will pave the road for new treatment options for this devastating disease. This article is highlighted in the In This Issue feature, p. 1825. Show less