Endothelium-targeted Ddx24 conditional knockout exacerbates ConA-induced hepatitis in mice due to vascular hyper-permeability.

BACKGROUND: Acute hepatitis is a progressive inflammatory disorder that can lead to liver failure. Endothelial permeability is the vital pathophysiological change involved in infiltrating inflammatory factors. DDX24 has been implicated in immune signaling. However, the precise role of DDX24 in immune-mediated hepatitis remains unclear. Here, we investigate the phenotype of endothelium-targeted Ddx24 conditional knockout mice with Concanavalin A (ConA)-induced hepatitis. METHODS: Mice with homozygous endothelium-targeted Ddx24 conditional knockout (Ddx24flox/flox; Cdh5-Cre+) were established using the CRISPR/Cas9 mediated Cre-loxP system. We investigated the biological functions of endothelial cells derived from transgenic mice and explored the effects of Ddx24 in mice with ConA-induced hepatitis in vivo. The mass spectrometry was performed to identify the differentially expressed proteins in liver tissues of transgenic mice. RESULT: We successfully established mice with endothelium-targeted Ddx24 conditional knockout. The results showed migration and tube formation potentials of murine aortic endothelial cells with DDX24 silencing were significantly promoted. No differences were observed between Ddx24flox/flox; Cdh5-Cre+ and control regarding body weight and length, pathological tissue change and embryogenesis. We demonstrated Ddx24flox/flox; Cdh5-Cre+ exhibited exacerbation of ConA-induced hepatitis by up-regulating TNF-α and IFN-γ. Furthermore, endothelium-targeted Ddx24 conditional knockout caused vascular hyper-permeability in ConA-injected mice by down-regulating vascular integrity-associated proteins. Mechanistically, we identified Ddx24 might regulate immune-mediated hepatitis by inflammation-related permeable barrier pathways. CONCLUSION: These findings prove that endothelium-targeted Ddx24 conditional knockout exacerbates ConA-induced hepatitis in mice because of vascular hyper-permeability. The findings indicate a crucial role of DDX24 in regulating immune-mediated hepatitis, suggesting DDX24 as a potential therapeutic target in the disorder.

DDX24 regulates the chemosensitivity of hepatocellular carcinoma to sorafenib via mediating the expression of SNORA18.

Sorafenib (SFN) is a multi-kinase inhibitor drug for the treatment of advanced hepatocellular carcinoma (HCC), but its limited efficacy is a major obstacle to the clinical outcomes of patients with HCC. We aimed to explore a novel molecular mechanism underlying the chemosensitivity of HCC to SFN, and to identify a promising therapeutic target for HCC treatment. In this study, bioinformatic analysis revealed that DDX24 was associated with poor survival in HCC cases, and significantly related to the pathways modulating tumor development. DDX24 regulated HCC cell proliferation and migration potentials. Moreover, reduction of DDX24 promoted the sorafenib-mediated inhibition of HCC cell growth and migration, the elevation of sorafenib-induced HCC cell apoptosis. DDX24 overexpression suppressed the inhibitory effect of SFN on cell proliferation and migration and reduced the apoptosis induced by SFN. Further, DDX24, combined with SFN treatment, presented a synergistic enhancement of the sensitivity of SFN to the growth and migration of HCC cells via AKT/ERK and the epithelial-mesenchymal transition (EMT) pathways, and that it modulated apoptosis via the caspase/PARP pathway. Mechanistically, SNORA18 served as a target gene for DDX24, regulating the chemosensitivity of sorafenib-treated HCC cells. Furthermore, SNORA18 knockdown or overexpression could partially reverse the inhibition or elevation of cell viability, colony formation and migration induced by DDX24 in sorafenib-treated HCC cells, respectively. Collectively, our results suggest that DDX24 regulates the chemosensitivity of HCC to SFN by mediating the expression of SNORA18, which may act as an effective therapeutic target for improving SFN efficiency in HCC treatment.

Inflammation-Regulated Nanodrug Sensitizes Hepatocellular Carcinoma to Checkpoint Blockade Therapy by Reprogramming the Tumor Microenvironment.

Immune checkpoint blockade (ICB) utilizing programmed death ligand-1 (PD-L1) antibody is a promising treatment strategy in solid tumors. However, in fact, more than half of hepatocellular carcinoma (HCC) patients are unresponsive to PD-L1-based ICB treatment due to multiple immune evasion mechanisms such as the hyperactivation of inflammation pathway, excessive tumor-associated macrophages (TAMs) infiltration, and insufficient infiltration of T cells. Herein, an inflammation-regulated nanodrug was designed to codeliver NF-κB inhibitor curcumin and PD-L1 antibody to reprogram the tumor microenvironment (TME) and activate antitumor immunity. The nanodrug accumulated in TME by an enhanced permeability and retention effect, where it left antibody to block PD-L1 on the membrane of tumor cells and TAMs due to pH-responsiveness. Simultaneously, a new curcumin-encapsulated nanodrug was generated, which was easily absorbed by either tumor cells or TAMs to inhibit the nuclear factor kappa-B (NF-κB) signal and related immunosuppressive genes. The inflammation-regulated nanodrug possessed good biocompatibility. Simultaneously, it reprogrammed TME effectively and exhibited an effective anticancer effect in immunocompetent mice. Overall, this study provided a potent strategy to improve the efficiency of ICB-based treatment for HCC.

Microbial and human transcriptional profiling of coronavirus disease 2019 patients: Potential predictors of disease severity.

The high morbidity of patients with coronavirus disease 2019 (COVID-19) brings on a panic around the world. COVID-19 is associated with sex bias, immune system, and preexisting chronic diseases. We analyzed the gene expression in patients with COVID-19 and in their microbiota in order to identify potential biomarkers to aid in disease management. A total of 129 RNA samples from nasopharyngeal, oropharyngeal, and anal swabs were collected and sequenced in a high-throughput manner. Several microbial strains differed in abundance between patients with mild or severe COVID-19. Microbial genera were more abundant in oropharyngeal swabs than in nasopharyngeal or anal swabs. Oropharyngeal swabs allowed more sensitive detection of the causative SARS-CoV-2. Microbial and human transcriptomes in swabs from patients with mild disease showed enrichment of genes involved in amino acid metabolism, or protein modification via small protein removal, and antibacterial defense responses, respectively, whereas swabs from patients with severe disease showed enrichment of genes involved in drug metabolism, or negative regulation of apoptosis execution, spermatogenesis, and immune system, respectively. Microbial abundance and diversity did not differ significantly between males and females. The expression of several host genes on the X chromosome correlated negatively with disease severity. In this way, our analyses identify host genes whose differential expression could aid in the diagnosis of COVID-19 and prediction of its severity via non-invasive assay.

RNA Helicase DDX24 Stabilizes LAMB1 to Promote Hepatocellular Carcinoma Progression.

Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies. Elucidating the underlying mechanisms of this disease could provide new therapeutic strategies for treating HCC. Here, we identified a novel role of DEAD-box helicase 24 (DDX24), a member of the DEAD-box protein family, in promoting HCC progression. DDX24 levels were significantly elevated in HCC tissues and were associated with poor prognosis of HCC. Overexpression of DDX24 promoted HCC migration and proliferation in vitro and in vivo, whereas suppression of DDX24 inhibited both functions. Mechanistically, DDX24 bound the mRNA618-624nt of laminin subunit beta 1 (LAMB1) and increased its stability in a manner dependent upon the interaction between nucleolin and the C-terminal region of DDX24. Moreover, regulatory factor X8 (RFX8) was identified as a DDX24 promoter-binding protein that transcriptionally upregulated DDX24 expression. Collectively, these findings demonstrate that the RFX8/DDX24/LAMB1 axis promotes HCC progression, providing potential therapeutic targets for HCC. SIGNIFICANCE: The identification of a tumor-promoting role of DDX24 and the elucidation of the underlying regulatory mechanism provide potential prognostic indicators and therapeutic approaches to help improve the outcome of patients with hepatocellular carcinoma.