Synthetic 3′,4′-Dihydroxyflavone Exerts Anti-Neuroinflammatory Effects in BV2 Microglia and a Mouse Model

Neuroinflammation is an immune response within the central nervous system against various proinflammatory stimuli. Abnormal activation of this response contributes to neurodegenerative diseases such as Parkinson disease, Alzheimer’s disease, and Huntington disease. Therefore, pharmacologic modulation of abnormal neuroinflammation is thought to be a promising approach to amelioration of neurodegenerative diseases. In this study, we evaluated the synthetic flavone derivative 3′,4′-dihydroxyflavone, investigating its anti-neuroinflammatory activity in BV2 microglial cells and in a mouse model. In BV2 microglial cells, 3′,4′-dihydroxyflavone successfully inhibited production of chemokines such as nitric oxide and prostaglandin E2 and proinflammatory cytokines such as tumor necrosis factor alpha, interleukin 1 beta, and interleukin 6 in BV2 microglia. It also inhibited phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB activation. This indicates that the anti-inflammatory activities of 3′,4′-dihydroxyflavone might be related to suppression of the proinflammatory MAPK and NF-κB signaling pathways. Similar anti-neuroinflammatory activities of the compound were observed in the mouse model. These findings suggest that 3′,4′-dihydroxyflavone is a potential drug candidate for the treatment of microglia-related neuroinflammatory diseases.

The Role of Sodium-taurocholate Co-transporting Polypeptide as a Receptor during HBV Infection

According to World Health Organization, more than 200 million people suffer with chronic hepatitis caused by Hepatitis B virus (HBV) infection worldwide. Chronic hepatitis B causes various complications including liver cirrhosis and hepatocellular carcinoma and approximately 0.5~4.2 million deaths occur annually due to HBV infection. Current therapies such as antivirals and vaccine are often hampered by drug intolerance, side effects, and long-time medication, therefore, the development of powerful anti-HBV drugs is demanded. Recently, sodium taurocholate co-transporting polypeptide (NTCP) receptor was revealed to play a pivotal role in HBV entry into hepatocytes. Cell lines transfected with NTCP receptor enables to analyze HBV life cycle by inducing HBV infection stably, but in vivo models still have some limitations such as high costs, restrictive differentiation, and unveiled cofactors related to human NTCP. Therefore, it requires well-established in vivo models to develop and evaluate novel therapeutic agents targeting NTCP receptor, and viral entry inhibitors that inhibit the early step of viral infection are potent sufficient to substitute for existing antivirals.

Current Advances in the Development of Vaccines and Therapeutic Agents Against MERS-coV

Middle East respiratory syndrome (MERS) is an emerging infectious disease caused by the betacoronavirus (MERS-CoV). Since the isolation and identification of MERS-CoV in 2012, cases have been spread to neighboring nations in Arabian Peninsula area and Europe. The recent outbreak of MERS in Korea confirmed that MERS-CoV is capable of causing epidemics through person-to-person transmission. Despite of its high mortality, there is no available effective vaccine and therapeutic agent partly due to its short history. So far, ribavirin and interferon therapy has been failed to prove its efficacy in human patients. Thus, there is an urgent need for the effective countermeasures such as vaccines and therapeutics. In the current review, recent advances in the development of vaccines and therapeutic antibodies have been discussed.

Regulation of Host Cell Signaling Pathways by Respiratory Syncytial Virus Nonstructural Protein NS1 and NS2

Human Respiratory Syncytial virus (hRSV) is a leading cause of severe lower respiratory tract diseases in the pediatric population.hRSV frequently causes severe morbidity and mortality in high risk groups including infants with congenital heart disease and the immunosuppressed patients. Although hRSV is recognized as a major public health threat and economic burden worldwide, there is no licensed vaccine and effective therapeutic agent. Viral nonstructural (NS) proteins have been known to play multiple functions for efficient viral replication and pathogenesis. Especially, diverse functions of influenza A virus NS1 have been extensively studies. Recent studies demonstrated that NS1 and NS2 of RSV also exert diverse functions to modulate cellular environment and antiviral immune responses. Since NS proteins of RSV are required for efficient replication and pathogenesis, NS mutant viruses have been tested as live-attenuated vaccines. This review will outline the recent progress in understanding the various functions of RSV NS1 and NS2.

Sensing DNA Viruses and Bacteria by Intracellular DNA Sensors

The innate immune system confers first-line defense against various pathogens including bacteria and viruses. Early detection of invading pathogens by the host depends on a limited number of specific pattern recognition receptors (PRRs) that detect pathogen associated molecular patterns (PAMPs) and activate signal transduction cascades that lead to activation of defense mechanisms. Among those sensors, RIG-I-like receptors (RLRs) play crucial roles in the detection of viruses by recognizing intracellular viral patterns such as viral RNAs to induce type-I interferon production. The discovery of intracellular RNA sensing mechanism by RIG-I prompted the investigations to find out intracellular DNA sensors. Recently, several proteins including DAI, AIM2, IFI16, and cGAS have been suggested as DNA sensing molecules to detect DNA viruses and bacteria, suggesting there are multiple receptors for microbial DNA. In this review, we discuss the current our understanding of sensing microbial DNA and subsequent induction of immune responses.