Byung-Kwan Lim

Jin SA, et al. Korean Circ J. 2025 Dec;56:e33. https://doi.org/10.4070/kcj.2025.0155

Hand, foot, and mouth disease (HFMD) can show severe clinical symptoms in children and infants, such as fever, mouth ulcers, and vesicular rashes on the palms and feet. Enterovirus 71 (EV71) is the leading cause of this disease. In this study, we investigated the antiviral effect of soluble scavenger receptor type B2 (SCAB2, CD36) to develop a new therapeutic approach for HFMD. Soluble SCAB2: Fc was generated by using the human IgG1 Fc region. The SCAB2 gene was cloned into the expression plasmid with human IgG1 Fc sequences (SCAB2:Fc/PCK). SCAB2:Fc/PCK plasmid was transfected into HEK293T cells for 72 hours. Then the cell protein was extracted, and the culture supernatant was collected. The supernatant SCAB2:Fc protein was concentrated, and its concentration was measured using a human IgG1 ELISA kit. SCAB2:Fc strongly blocked the EV71 target cell entry in a dose-dependent manner. The antiviral activity of SCAB2:Fc was observed by western blot analysis and reverse transcription PCR (RT-PCR). VP1 capsid protein and virus-positive-strand RNA were significantly decreased in 100 ng/ml of SCAB2:Fc treatment. Transcription factor, eIF4G1, and cleaved caspases3 levels were reduced considerably with SCAB2:Fc treatment. Moreover, inhibiting virus infection strongly suppressed virus replication and cell proliferation regulating MAPK signaling. The phosphorylation of p38 and ERK1/2 was significantly decreased by SCAB2:Fc treatment. These data suggested that SCAB2:Fc inhibited EV71 infection and virus replication-induced MAPK signaling activity. In this study, the antiviral effect of soluble SCAB2 was investigated to develop an EV71 treatment. Soluble SCAB2:Fc showed potent antiviral activity in vitro, and it could be a potential candidate material to use as a therapeutic drug for EV71induced HFMD.

Cells interact with each other for proper function and homeostasis. Often, co-expression of ligand-receptor pairs from the single-cell RNAseq (scRNAseq) has been used to identify interacting cell types. Recently, RNA sequencing of physically interacting multi-cells has been used to identify interacting cell types without relying on co-expression of ligand-receptor pairs. This opens a new avenue to study the expression of interacting cell types. We present DeepDoublet, a deep-learning-based tool to decompose the transcriptome of physically interacting two cells (or doublet) into two sets of transcriptome. Applying DeepDoublet to the doublets of hepatocyte and liver endothelial cells (LECs), we successfully decomposed into the transcriptome of each cell type. Especially, DeepDoublet identified specific expression of hepatocytes when they are interacting with LECs. Among them was Angptl3 which has a role in blood vessel formation. DeepDoublet is a tool to identify neighboring cell-dependent gene expression.

The current COVID-19 mRNA vaccines were developed and applied for pandemic-emergent conditions. These vaccines use a small piece of the virus’s genetic material (mRNA) to stimulate an immune response against COVID-19. However, their potential effects on individuals with chronic inflammatory conditions and vaccination routes remain questionable. Therefore, we investigated the effects of mRNA vaccines in a mouse model of chronic inflammation, focusing on their cardiac toxicity and immunogenicity dependent on the injection route. mRNA vaccine intravenous administration with or without chronic inflammation exacerbated cardiac pericarditis and myocarditis; immunization induced mild inflammation and inflammatory cytokine IL-1beta and IL-6 production in the heart. Further, IV mRNA vaccination induced cardiac damage in LPS chronic inflammation, particularly serum troponin I (TnI), which dramatically increased. IV vaccine administration may induce more cardiotoxicity in chronic inflammation. These findings highlight the need for further research to understand the underlying mechanisms of mRNA vaccines with chronic inflammatory conditions dependent on injection routes.

Metabolic dysfunction–associated fatty liver disease (MAFLD) is a common liver disease associated with obesity and is caused by the accumulation of ectopic fat without alcohol consumption. Coxsackievirus and adenovirus receptor (CAR) are vital for cardiac myocyte-intercalated discs and endothelial cell-to-cell tight junctions. CAR has also been reported to be associated with obesity and high blood pressure. However, its function in the liver is still not well understood. The liver of obese mice exhibit elevated CAR mRNA and protein levels. Furthermore, in the liver of patients with non-alcoholic steatohepatitis, CAR is reduced in hepatocyte cell–cell junctions compared to normal levels. We generated liver-specific CAR knockout (KO) mice to investigate the role of CAR in the liver. Body and liver weights were not different between wild-type (WT) and KO mice fed a paired or high-fat diet (HFD). However, HFD induced significant liver damage and lipid accumulation in CAR KO mice compared with WT mice. Additionally, inflammatory cytokines transcription, hepatic permeability, and macrophage recruitment considerably increased in CAR KO mice. We identified a new interaction partner of CAR using a protein pull-down assay and mass spectrometry. Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3C (APOBEC3C) demonstrated a complex relationship with CAR, and hepatic CAR expression tightly regulated its level. Moreover, Apolipoprotein B (ApoB) and Low-density lipoprotein receptor (LDLR) levels correlated with APOBEC3C expression in the liver of CAR KO mice, suggesting that CAR may regulate lipid accumulation by controlling APOBEC3C activity. In this study, we showed that hepatic CAR deficiency increased cell-to-cell permeability. In addition, CAR deletion significantly increased hepatic lipid accumulation by inducing ApoB and LDLR expression. Although the underlying mechanism is unclear, CARs may be a target for the development of novel therapies for MAFLD.

Coxsackievirus B3 (CVB3) is a positive single-strand RNA genome virus which belongs to the enterovirus genus in the picornavirus family, like poliovirus. It is one of the most prevalent pathogens that cause myocarditis and pancreatitis in humans. However, a suitable therapeutic medication and vaccination have yet to be discovered. Caboxamycin, a benzoxazole antibiotic isolated from the culture broth of the marine strain Streptomyces sp., SC0774, showed an antiviral effect in CVB3-infected HeLa cells and a CVB3-induced myocarditis mouse model. Caboxamycin substantially decreased CVB3 VP1 production and cleavage of translation factor eIF4G1 from CVB3 infection. Virus-positive and -negative strand RNA was dramatically reduced by caboxamycin treatment. In addition, the cleavage of the pro-apoptotic molecules BAD, BAX, and caspase3 was significantly inhibited by caboxamycin treatment. In animal experiments, the survival rate of mice was improved following caboxamycin treatment. Moreover, caboxamycin treatment significantly decreased myocardial damage and inflammatory cell infiltration. Our study showed that caboxamycin dramatically suppressed cardiac inflammation and mouse death. This result suggests that caboxamycin may be suitable as a potential antiviral drug for CVB3.

The implications of administration of mRNA vaccines to individuals with chronic inflammatory diseases, including myocarditis, rheumatoid arthritis (RA), and inflammatory bowel disease (IBD), are unclear. We investigated mRNA vaccine effects in a chronic inflammation mouse model implanted with an LPS pump, focusing on toxicity and immunogenicity. Under chronic inflammation, mRNA vaccines exacerbated cardiac damage and myocarditis, inducing mild heart inflammation with heightened pro-inflammatory cytokine production and inflammatory cell infiltration in the heart. Concurrently, significant muscle damage occurred, with disturbances in mitochondrial fusion and fission factors signaling impaired muscle repair. However, chronic inflammation did not adversely affect muscles at the vaccination site or humoral immune responses; nevertheless, it partially reduced the cell-mediated immune response, particularly T-cell activation. These findings underscore the importance of addressing mRNA vaccine toxicity and immunogenicity in the context of chronic inflammation, ensuring their safe and effective utilization, particularly among vulnerable populations with immune-mediated inflammatory diseases.

Coxsackievirus B3 (CVB3) is one of the most common pathogens that cause myocarditis in humans. However, a sufficient therapeutic drug was not developed yet. Caboxamycin, a benzoxazole antibiotic, isolated from the culture broth of the marine strain Streptomyces sp., SC0774, displayed an antiviral effect in the CVB3-infected HeLa cells and CVB3-induced myocarditis mouse model. Caboxamycin significantly inhibited CVB3 VP1 production and cleavage of translation factor eIF4G1 from CVB3-infected HeLa cells at a 100 μg/ml concentration. Moreover, virus RNA amplification was dramatically reduced by caboxamycin treatment in HeLa cells. The caboxamycin cardiac protective effect was observed on the CVB3-mediated myocarditis mice model. The caboxamycin-treated mice survival was significantly increased compared to untreated mice (treated vs untreated, 100 vs 45 %). Heart histologic findings showed that myocardium damage and inflammation were significantly decreased by caboxamycin treatment. Caboxamycin directly inhibited caspase3 activity and cardiac myocytes apoptosis. These results suggested that caboxamycin strongly suppressed cardiac myocyte apoptosis and effectively inhibited the proliferation of CVB3 from in vitro and in vivo conditions. Furthermore, this study proposed that caboxamycin could potentially be applied in developing a new antiviral drug for CVB3-induced myocarditis.