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Objective To investigate the change in interleukin-33 (IL-33) in the peripheral blood of hepatocellular carcinoma (HCC) patients and the role and potential mechanism of IL-33 in regulating CD8 + T cell function in HCC patients. Methods A total of 44 HCC patients who attended Shaanxi Provincial People's Hospital from April 2019 to January 2020 and 20 healthy controls were enrolled. Peripheral blood was collected, and plasma and peripheral blood mononucleated cells (PBMCs) were isolated; ELISA was used to measure the plasma levels of IL-33 and its receptor ST2, and quantitative real-time PCR was used to measure the relative mRNA expression levels of IL-33 and ST2 in PBMCs. CD8 + T cells were purified and stimulated with recombinant IL-33; CCK-8 assay was used to assess cell proliferation, enzyme-linked immunospot assay was used to measure the secretion of perforin and granzyme B, and flow cytometry was used to measure the expression of PD-1, LAG-3, and CTLA-4; changes in cell proliferation, secretion of cytotoxic molecules, and immune checkpoint molecules after IL-33 stimulation were compared. CD8 + T cells were co-cultured with HepG2 cells; the expression of lactate dehydrogenase was measured to calculate the proportion of dead HepG2 cells induced by CD8 + T cells, and the change in the killing function of CD8 + T cells after IL-33 stimulation was compared. The t -test or the paired t -test was used for comparison of continuous data between two groups, and a Pearson correlation analysis was performed. Results Compared with the control group, the HCC group had significantly lower plasma level of IL-33 (269.80±63.08 pg/ml vs 339.50±64.43 pg/ml, t =4.072, P 0.05). The proportion of CD8 + T cells was not correlated with the plasma level of IL-33 or ST2 (both P > 0.05). Compared with the control group, the HCC group had significantly lower levels of perforin and granzyme B (both P 0.05), but it promoted the secretion of perforin and granzyme B ( P < 0.05). Compared with the control group, the HCC group had a significant reduction in the killing activity of CD8 + T cells ( P < 0.05), and stimulation with recombinant IL-33 enhanced the killing function of CD8 + T cells, which was mainly reflected in the increases in the proportion of dead HepG2 cells ( P < 0.05) and the secretion of IFNγ and TNFα ( P < 0.05). Conclusion There is a reduction in the plasma level of IL-33 in HCC patients. IL-33 can enhance the killing activity of CD8 + T cells by promoting the secretion of perforin and granzyme B, which provides a new target for the treatment of HCC.
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Host cellular receptors are key determinants of virus tropism and pathogenesis. Virus utilizes multiple receptors for attachment, entry, or specific host responses. However, other than ACE2, little is known about SARS-CoV-2 receptors. Furthermore, ACE2 cannot easily interpret the multi-organ tropisms of SARS-CoV-2 nor the clinical differences between SARS-CoV-2 and SARS-CoV. To identify host cell receptors involved in SARS-CoV-2 interactions, we performed genomic receptor profiling to screen almost all human membrane proteins, with SARS-CoV-2 capsid spike (S) protein as the target. Twelve receptors were identified, including ACE2. Most receptors bind at least two domains on S protein, the receptor-binding-domain (RBD) and the N-terminal-domain (NTD), suggesting both are critical for virus-host interaction. Ectopic expression of ASGR1 or KREMEN1 is sufficient to enable entry of SARS-CoV-2, but not SARS-CoV and MERS-CoV. Analyzing single-cell transcriptome profiles from COVID-19 patients revealed that virus susceptibility in airway epithelial ciliated and secretory cells and immune macrophages highly correlates with expression of ACE2, KREMEN1 and ASGR1 respectively, and ACE2/ASGR1/KREMEN1 (ASK) together displayed a much better correlation than any individual receptor. Based on modeling of systemic SARS-CoV-2 host interactions through S receptors, we revealed ASK correlation with SARS-CoV-2 multi-organ tropism and provided potential explanations for various COVID-19 symptoms. Our study identified a panel of SARS-CoV-2 receptors with diverse binding properties, biological functions, and clinical correlations or implications, including ASGR1 and KREMEN1 as the alternative entry receptors, providing insights into critical interactions of SARS-CoV-2 with host, as well as a useful resource and potential drug targets for COVID-19 investigation.
