Search

Omsk hemorrhagic fever virus (OHFV) is a tick-borne flavivirus classified as a biosafety level-4 (BSL4) pathogen. Studies of OHFV are restricted to be conducted within BSL4 laboratories. Currently, no commercial vaccines or antiviral drugs are available against OHFV infection. In this study, we recovered a replication-deficient OHFV with an NS1 deletion (OHFV-ΔNS1) and reporter virus replacing NS1 with the Gaussia luciferase (Gluc) (OHFV-ΔNS1-Gluc). Both the defective OHFV-ΔNS1 and OHFV-ΔNS1-Gluc virus could only replicate efficiently in the BHK21 cell line expressing NS1 (BHK21(NS1)) but not in naïve BHK21 cells. The Gluc reporter gene of OHFV-ΔNS1-Gluc virus was maintained stably after serial passaging of BHK21(NS1) cells and was used to surrogate the replication of OHFV. Using NITD008, OHFV-ΔNS1-Gluc virus was validated for antiviral screening, and high-throughput screening parameters were optimized in a 96-well plate format with a calculated Z′ value above 0.5. The OHFV-ΔNS1-Gluc reporter virus is a powerful tool for antiviral screening as well as viral replication and pathogenesis studies in BSL2 laboratories.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus, which is highly pathogenic and classified as a biosafety level 3 (BSL-3) agent, has greatly threatened global health and efficacious antivirals are urgently needed. The high requirement of facilities to manipulate the live virus has limited the development of antiviral study. Here, we constructed a reporter replicon of SARS-CoV-2, which can be handled in a BSL-2 laboratory. The Renilla luciferase activity effectively reflected the transcription and replication levels of the replicon genome. We identified the suitability of the replicon in antiviral screening using the known inhibitors, and thus established the replicon-based high-throughput screening (HTS) assay for SARS-CoV-2. The application of the HTS assay was further validated using a few hit natural compounds, which were screened out in a SARS-CoV-2 induced cytopathic-effect-based HTS assay in our previous study. This replicon-based HTS assay will be a safe platform for SARS-CoV-2 antiviral screening in a BSL-2 laboratory without the live virus.

The emerging SARS-CoV-2 infection associated with the outbreak of viral pneumonia in China is ongoing worldwide. There are no approved antiviral therapies to treat this viral disease. Here we examined the antiviral abilities of three broad-spectrum antiviral compounds gemcitabine, lycorine and oxysophoridine against SARS-CoV-2 in cell culture. We found that all three tested compounds inhibited viral replication in Vero-E6 cells at noncytotoxic concentrations. The antiviral effect of gemcitabine was suppressed efficiently by the cytidine nucleosides. Additionally, combination of gemcitabine with oxysophoridine had an additive antiviral effect against SARS-CoV-2. Our results demonstrate that broad-spectrum antiviral compounds may have a priority for the screening of antiviral compounds against newly emerging viruses to control viral infection.

Aims: Endothelial dysfunction appears in early diabetes mellitus partially because of epidermal growth factor receptor (EGFR) abnormal activation and downstream oxidative stress. The aim of this study was to determine whether Y396, a synthesized analog of rhynchophylline, could protect against endothelial dysfunction in diabetes and the underlying molecular mechanism. Results: Y396 could directly target the EGFR and inhibit its phosphorylation induced by high glucose and EGF, downstream translocation to the nucleus of E2F1, and its transcriptional activity and expression of Nox4. Diabetes-induced endothelium malfunction was ameliorated by Y396 treatment through EGFR inhibition. Downstream oxidative stress was decreased by Y396 in the aortas of type 1 diabetes mellitus mice and primary rat aorta endothelial cells (RAECs). Y396 could also ameliorate tunicamycin-induced oxidative stress in the aorta and RAECs. In addition, we again determined the protective effects of Y396 on high-fat diet/streptozotocin-induced type 2 diabetes mellitus. Innovation: This is the first study to demonstrate that Y396, a novel rhynchophylline analog, suppressed high-glucose-induced endothelial malfunction both in vivo and in vitro by inhibiting abnormal phosphorylation of EGFR. Our work uncovered EGFR as a novel therapeutic target and Y396 as a potential therapy against diabetes-induced complication. Conclusion: Y396 could directly bind with EGFR, and inhibit its phosphorylation and downstream E2F1 transcriptional activity. It could also preserve tunicamycin-evoked endothelial dysfunction and oxidative stress. It could protect against diabetes-induced endothelium malfunction in vivo through EGFR inhibition and downstream oxidative stress. Antioxid. Redox Signal. 32, 743-765.

Aims Ischemic stroke is one of the leading causes of death worldwide. MicroRNAs (miRNAs) have been reported to be implicated in cerebral hypoxia injury and could serve as a therapeutic target. As the third gasotransmitter, hydrogen sulfide (H2S) plays a critical role in hypoxia-induced injury in the central nervous system. Cystathionine β-synthase (CBS) is the main enzyme catalyzing the production of H2S in brain. The objective of this study was to investigate the effect of miR-125b-5p on protecting against oxygen and glucose deprivation (OGD) injury in PC-12 cells by regulating CBS and H2S generation. Results The level of miR-125b-5p was increased in the rat MCAO model as well as OGD model in PC-12 cells. Meanwhile, CBS expression was remarkably downregulated. Overexpression of miR-125b-5p reduced CBS expression, decreased the H2S generation, and deteriorated OGD injury in PC-12 cells. On the contrary, silencing miR-125b-5p protected PC-12 cells from OGD injury by upregulated CBS and H2S levels. We found the protective effect of miR-125b-5p inhibition was associated with anti-oxidative and anti-apoptotic cell signaling through decreasing ROS level and reducing mitochondrial membrane potential (ΔΨm). Furthermore, the protective effect was absent when CBS was knockdown in PC-12 cells. Innovation and conclusion Our research discovered the regulation of CBS by miR-125b-5p. Besides, we provide the evidence for the therapeutic potential of miR-125b-5p inhibition for cerebral ischemia via CBS/H2S pathway.

Zika virus (ZIKV) is an important emerging human pathogen associated with microcephaly, Guillain-Barre syndrome and meningoencephalitis. Developing rapid and reliable HTS assay is important for ZIKV drug discovery. Here, we constructed a dicistronic ZIKV replicon (ZIKV-Pac-Rluc-Rep) that contained the Renilla luciferase (Rluc) reporter gene separated from the puromycin N-acetyl-transferase (Pac) selectable marker by a short peptide cleavage site. A clonal replicon cell line stably expressing high level of ZIKV replicon was established by selection with puromycin. By optimizing cell number, compound concentration and incubation time, a robust replicon cell-based HTS assay was developed with a calculated Z' value of >0.5. The fully optimized assay was further validated using several known flavivirus replication inhibitors. Altogether, the replicon cell-based HTS assay developed in this study will facilitate the discovery of antiviral compounds against ZIKV.

In this study, an in vitro ligation method was developed to assemble a full-length infectious cDNA clone of the Zika virus (ZIKV). Four contiguous cDNA subclones covering the complete ZIKV genome were constructed with unique BglI restriction sites at the ends of each fragment. The BglI restriction sites only allow in vitro ligation to happen between interconnecting restriction sites from adjacent cDNA fragments, resulting in an intact full-length cDNA of ZIKV. RNA transcripts derived from the full-length cDNA were infectious. The recombinant virus replicated as efficiently as the wild-type virus with similar growth kinetics and plaque morphologies in Vero and C6/36 cells. Both viruses were inhibited by NITD008 treatment. This in vitro ligation method will facilitate manipulation of the viral genome through genetic modifications of four separated subclones of ZIKV for the rapid and rational development of candidate vaccines and viral replication study.

The aim of the present study was to compare the different effects of berberine (Ber) and Coptischinensis extract (CCE) on a rat model of type 2 diabetes mellitus (T2DM), and the islet Rin‑5f cell line was used to examine the differences between Ber and CCE and the underlying mechanisms. CCE was extracted and purified prior to analysis. Male Sprague‑Dawley rats were provided with a high‑fat diet to induce insulin resistance prior to injecting with streptozotocinto establish the T2DM model, the T2DM rats were treated with Ber and CCE, and blood samples and pancreatic tissues were obtained and compared to examine T2DM metabolic syndromes among the groups of rats, which included healthy rats, model rats, and model rats treated with Ber and CCE at different doses between 0 and 8 weeks. The protective effects of Ber and CCE on the Rin‑5f islet cell line were also evaluated. The effects on Rin‑5f cell proliferation and cell cycle, glucose‑stimulated insulin release test (GSIS), the anti‑apoptotic effects caused by fat induction, and protein expression levels of poly ADP‑ribose polymerase (PARP‑1) were evaluated. The results showed that the content of the prepared CCE was 96.07% for five alkaloids. When it was used for treatment of the T2DM rats, compared with Ber, metformin and rosiglitazone, the fasting blood glucose, glucosylated serum protein (GSP) and glucose infusion rate indicesin the fasting rats were ameliorated, compared with those in the T2MD rats, with no significant differences between treatment with Ber or CCE and metformin or rosiglitazone. The indices of mean optical density and fasting β‑cell function index (FBCI) were different following treatment with Ber and CCE, compared with those in the model rats, which may have stimulated the pancreatic secretion of insulin. When Ber and CCE were used to examine the protective effects on Rin‑5F cells, it was found that the Rin‑5f cell GSIS, cell cycle, lipotoxic islet cell proliferation and protein expression of PARP‑1 were altered and improved, which may have protected pancreatic islet β‑cells by improving islet β‑cell proliferation and the protein expression of PARP‑1. CCE and Ber exerted similar effects when used for the treatment of T2MD rats, and may have stimulated the pancreatic secretion of insulin through the protective effect on islet β‑cells via improving islet β‑cell proliferation and the protein expression of PARP‑1.

Leonurine, also named SCM-198, which was extracted from Herba leonuri, displayed a protective effect on various cardiovascular and brain diseases, like ischemic stroke. Ischemic stroke which is the leading cause of morbidity and mortality, ultimately caused irreversible neuron damage. This study is aimed at exploring the possible therapeutic potential of SCM-198 in the protection against postischemic neuronal injury and possible underlying mechanisms. A transient middle cerebral artery occlusion (tMCAO) rat model was utilized to measure the protective effect of SCM-198 on neurons. TEM was used to determine neuron ultrastructural changes. The brain slices were stained with Nissl staining solution for Nissl bodies. Fluoro-Jade B (FJB) was used for staining the degenerating neurons. In the oxygen-glucose deprivation and re-oxygenation (OGD/R) model of bEnd.3 cells treated with SCM-198 (0.1, 1, 10 μM). Then, the bEnd.3 cells were cocultured with SH-SY5Y cells. Cell viability, MDA level, CAT activity, and apoptosis were examined to evaluate the cytotoxicity of these treatments. Western blot and immunofluorescent assays were used to examine the expression of protein related to the p-STAT3/NOX4/Bcl-2 signaling pathway. Coimmunoprecipitation was performed to determine the interaction between p-STAT3 and NOX4. In the transient middle cerebral artery occlusion (tMCAO) rat model, we found that treatment with SCM-198 could ameliorate neuron morphology and reduce the degenerating cell and neuron loss. In the in vitro model of bEnd.3 cell oxygen-glucose deprivation and reoxygenation (OGD/R), treatment with SCM-198 restored the activity of catalase (CAT), improved the expression of Cu-Zn superoxide dismutase (SOD1), and decreased the malondialdehyde (MDA) production. SCM-198 treatment prevented OGD/R-induced cell apoptosis as indicated by increased cell viability and decreased the number of TUNEL-positive cells, accompanied with upregulation of Bcl-2 and Bcl-xl protein and downregulation Bax protein. The results were consistent with SH-SY5Y cells which coculture with bEnd.3 cells. The forthcoming study revealed that SCM-198 activated the p-STAT3/NOX4/Bcl-2 signaling pathway. All the data indicated that SCM-198 protected against oxidative stress and neuronal damage in in vivo and in vitro injury models via the p-STAT3/NOX4/Bcl-2 signaling pathway. Our results suggested that SCM-198 could be the potential drug for neuroprotective effect through stabilizing endothelial cell function.

Cerasus humilis is a species of small, perennial, drought-resistant and multipurpose deciduous shrub grown in arid and semi-arid conditions in northern China. In this study, an efficient protocol for the rapid micropropagation of C. humilis has been standardized using stem and/or leaf explants. Direct multiple shoot induction was observed when the stem explants were cultured on Murashige and Skoog (MS) medium supplemented with different plant growth regulators. The highest shoot induction was obtained when stem explants from adult trees were cultured on MS medium supplemented with 2.0 mg L−1 6-benzyladenine (6-BA) and 0.9 mg L−1 α-naphthaleneacetic acid (NAA). The leaf and stem explants cultured on MS medium with 1.0 mg L−1 6-BA and 0.6 mg L−1 NAA, and 0.5 mg L−1 6-BA and 0.8 mg L−1 NAA, respectively, produced the highest induction frequency of callus. Maximum proliferation of callus was observed on MS medium containing a combination of 0.5 mg L−1 6-BA with 0.6 mg L−1 2,4-dichlorophenoxyacetic aci...

In the present study, our bioinformatics analysis first reveals the existence of a conserved guanine-rich sequence within the Zaire ebolavirus L gene. Using various methods, we show that this sequence tends to fold into G-quadruplex RNA. TMPyP4 treatment evidently inhibits L gene expression at the RNA level. Moreover, the mini-replicon assay demonstrates that TMPyP4 effectively inhibits the artificial Zaire ebolavirus mini-genome and is a more potent inhibitor than ribavirin. Although TMPyP4 treatment reduced the replication of the mutant mini-genome when G-quadruplex formation was abolished in the L gene, its inhibitory effect was significantly alleviated compared with wild-type. Our findings thus provide the first evidence that G-quadruplex RNA is present in a negative-sense RNA virus. Finally, G-quadruplex RNA stabilization may represent a new therapeutic strategy against Ebola virus disease.

Here, we describe a cell culture-based procedure for isolating the infectious ZIKV (GenBank KU963796) from a human serum sample (ca. 50 μL) with an extremely low viral load (Ct value = 32).

Cerasus humilis, grown in the northern areas of China, may experience water deficit during their life cycle, which induces oxidative stress. Our present study was conducted to evaluate the role of oxidative stress management in the leaves of twoC. humilisgenotypes, HR (drought resistant) and ND4 (drought susceptible), when subjected to a long-term soil drought (WS). The HR plants maintained lower membrane injury due to low ROS and MDA accumulation compared to ND4 plants during a long-term WS. This is likely attributed to global increase in the activities of superoxide dismutase (SOD) isoenzymes and enzymes of the ascorbate-glutathione (AsA-GSH) cycle and maintenance of ascorbate (AsA) levels. Consistent closely with enzymes activities, the expression of cytosolic ascorbate peroxidase (cAPX) and dehydroascorbate reductase (DHAR) followed a significant upregulation, indicating that they were regulated at the transcriptional level for HR plants exposed to WS. In contrast, ND4 plants exhibited high ROS levels and poor antioxidant enzyme response, leading to enhanced membrane damage during WS conditions. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability ofC. humilisplants to induce antioxidant defense under drought conditions.

Japanese encephalitis virus (JEV), a major cause of Japanese encephalitisis, is an arbovirus that belongs to the genus Flavivirus of the family Flaviviridae. Currently, there is no effective drugs available for the treatment of JEV infection. Therefore, it is important to establish efficient antiviral screening system for the development of antiviral drugs. In this study, we constructed a full-length infectious clone of eGFP-JEV reporter virus by inserting the eGFP gene into the capsid-coding region of the viral genome. The reporter virus RNA transfected-BHK-21 cells generated robust eGFP fluorescence signals that were correlated well with viral replication. The reporter virus displayed growth kinetics similar to wild type (WT) virus although replicated a little slower. Using a known JEV inhibitor, NITD008, we demonstrated that the reporter virus could be used to identify inhibitors against JEV. Furthermore, an eGFP-JEV-based high throughput screening (HTS) assay was established in a 96-well format and used for screening of 1,443 FDA-approved drugs. Sixteen hit drugs were identified to be active against JEV. Among them, five compounds which are lonafarnib, cetylpyridinium chlorid, cetrimonium bromide, nitroxoline and hexachlorophene, are newly discovered inhibitors of JEV, providing potential new therapies for treatment of JEV infection., Highlights • The eGFP-JEV reporter virus was established. • The eGFP-JEV -based high throughput screening (HTS) assay was developed with a calculated Z′ factor of >0.5. • A library of 1,443 FDA-approved drugs was screened to determine their ability to inhibit JEV infection using this HTS assay. • 5 novel hit drugs were identified to be active against JEV infection.

(2S,3S,4S,5R,6R)-6-(4-((4-guanidinobutoxy)carbonyl)-2,6-dihydroxyphenoxy)-3,4,5-trihydroxytetrahydro-2H-pyran-2-carboxylic acid (ZYZ-488) was discovered as a novel inhibitor of apoptotic protease activating factor-1 (Apaf-1). In present work, a surface plasmon resonance (SPR) assay confirms the direct binding between ZYZ-488 and Apaf-1 and this interaction was found to be able to block the recruitment of procaspase-9 by Apaf-1. This study also shows that the treatment of MI (myocardial infarction) mice with this novel Apaf-1 inhibitor remarkably reduces the infarct size, improves cardiac functions, and attenuates the histopathology changes caused by MI. Meanwhile, here it is shown that ZYZ-488 decreases myocardial enzyme release, inhibits cardiomyocyte apoptosis, and suppresses the activation of the downstream cascade of caspases. Moreover, in silico prediction validated the drug-like properties of ZYZ-488. In conclusion, our findings present the first piece of evidence indicating the interaction between Apaf-1 and procaspase-9 as a novel therapeutic target in myocardial infarction and suggesting ZYZ-488 as a promising therapeutic option for myocardial infarction disease.

Japanese encephalitis virus (JEV), an important pathogen in Eastern and Southern Asia and the Pacific, has spread to Australia and other territories in recent years. Although the vaccine for JEV has been used in some countries, development of efficient antiviral drugs is still an urgent requirement. Replicon systems have been widely used in the research of viral replication and antiviral screening for West Nile virus (WNV), yellow fever virus (YFV) and dengue virus (DENV). Here, a novel JEV replicon harboring the Rluc and Pac gene (JEV-Pac-Rluc-Rep) was constructed. Furthermore, we established a BHK-21 cell line harboring JEV-Pac-Rluc-Rep (BHK-21/PAC/Rluc cell line) through continuous puromycin selection. Characterization of cell line stability showed that the replicon RNA could persistently replicate in this cell line for at least up to 10 rounds of passage. Using a known flavivirus inhibitor, the JEV replicon cell line was validated for antiviral screening. The JEV replicon cell line will be a valuable tool for both compound screening and viral replication studies.

Stroke is a leading cause of morbidity and mortality globally. Leonurine (also named SCM-198), a compound extracted fromHerba leonuri, was effective on the prevention of various cardiovascular and brain diseases. The purpose of this study was to explore the possible therapeutic potential of SCM-198 against ischemia reperfusion injury and underlying mechanisms. In the in vivo transient middle cerebral artery occlusion (tMCAO) rat model, we found that treatment with SCM-198 could decrease infarct volume and improve neurological deficit by protecting against blood-brain barrier (BBB) breakdown. In the in vitro model of cell oxygen-glucose deprivation and reoxygenation (OGD/R), consistent results were obtained with decreased reactive oxygen species (ROS) production and maintained the BBB integrity. Further study demonstrated that SCM-198 increased the expression of histone deacetylase- (HDAC-) 4 which could inhibit NADPH oxidase- (NOX-) 4 and matrix metalloproteinase- (MMP-) 9 expression, resulting in the elevation of tight junction proteins, including claudin-5, occludin, and zonula occluden- (ZO-) 1. These results indicated SCM-198 protected BBB integrity by regulating the HDAC4/NOX4/MMP-9 tight junction pathway. Our findings provided novel insights into the protective effects and mechanisms of SCM-198 on ischemic stroke, indicating SCM-198 as a new class of potential drug against acute onset of ischemic stroke.

Flavivirus includes a large group of human pathogens with medical importance. Especially, neurotropic flaviviruses capable of invading central and peripheral nervous system, e.g. Japanese encephalitis virus (JEV) and Zika virus (ZIKV), are highly pathogenic to human and constitute major global health problems. However, the dynamic dissemination and pathogenesis of neurotropic flavivirus infections remain largely unknown. Here, using JEV as a model, we rationally designed and constructed a recombinant reporter virus that stably expressed Renilla luciferase (Rluc). The resulting JEV reporter virus (named Rluc-JEV) and parental JEV exhibited similar replication and infection characteristics, and the magnitude of Rluc activity correlated well with progeny viral production in vitro and in vivo. By using in vivo bioluminescence imaging (BLI) technology, we dissected the replication and dissemination dynamics of JEV infection in mice upon different inoculation routes. Interestingly, besides replicating in mouse brain, Rluc-JEV predominantly invaded the abdominal organs in mice with typical viscerotropism. Further tests in mice deficient in type I interferon (IFN) receptors demonstrated robust and prolonged viral replication in the intestine, spleen, liver, kidney and other abdominal organs. Combined with histopathological and immunohistochemical results, the host type I IFN signaling was evidenced as the major barrier to the viscerotropism and pathogenicity of this neurotropic flavivirus. Additionally, the Rluc-JEV platform was readily adapted for efficacy assay of known antiviral compounds and a live JE vaccine. Collectively, our study revealed abdominal organs as important targets of JEV infection in mice and profiled the unique viscerotropism trait controlled by the host type I IFN signaling. This in vivo visualization technology described here provides a powerful tool for testing antiviral agents and vaccine candidates for flaviviral infection.

Flavivirus nonstructural protein 2B (NS2B) is a transmembrane protein that functions as a cofactor for viral NS3 protease. The cytoplasmic region (amino acids 51 to 95) alone of NS2B is sufficient for NS3 protease activity, whereas the role of transmembrane domains (TMDs) remains obscure. Here, we demonstrate for the first time that flavivirus NS2B plays a critical role in virion assembly. Using Japanese encephalitis virus (JEV) as a model, we performed a systematic mutagenesis at the flavivirus conserved residues within the TMDs of NS2B. As expected, some mutations severely attenuated (L38A and R101A) or completely destroyed (G12L) viral RNA synthesis. Interestingly, two mutations (G37L and P112A) reduced viral RNA synthesis and blocked virion assembly. None of the mutations affected NS2B-NS3 protease activity. Because mutations G37L and P112A affected virion assembly, we selected revertant viruses for these two mutants. For mutant G37L, replacement with G37F, G37H, G37T, or G37S restored virion assembly. For mutant P112A, insertion of K at position K127 (leading to K127KK) of NS2B rescued virion assembly. A biomolecular fluorescent complementation (BiFC) analysis demonstrated that (i) mutation P112A selectively weakened NS2B-NS2A interaction and (ii) the adaptive mutation K127KK restored NS2B-NS2A interaction. Collectively, our results demonstrate that, in addition to being a cofactor for NS3 protease, flavivirus NS2B also functions in viral RNA replication, as well as virion assembly. IMPORTANCE Many flaviviruses are important human pathogens. Understanding the molecular mechanisms of the viral infection cycle is essential for vaccine and antiviral development. In this study, we demonstrate that the TMDs of JEV NS2B participate in both viral RNA replication and virion assembly. A viral genetic study and a BiFC assay demonstrated that interaction between NS2B and NS2A may participate in modulating viral assembly in the flavivirus life cycle. Compensatory-mutation analysis confirmed that there was a correlation between viral assembly and NS2B-NS2A interaction. TMDs of NS2B may serve as novel antiviral targets to prevent flavivirus infection, and the structure determination of NS2B will help us to understand the functional mechanism of NS2B in viral RNA replication and assembly. The results have uncovered a new function of flavivirus NS2B in virion assembly, possibly through interaction with the NS2A protein.

The ongoing Zika virus (ZIKV) outbreak has rapidly spread to new areas of Americas, which were the first transmissions outside its traditional endemic areas in Africa and Asia. Due to the link with newborn defects and neurological disorder, numerous infected cases throughout the world and various mosquito vectors, the virus has been considered to be an international public health emergency. In the present study, we developed a SYBR Green based one-step real-time RT-PCR assay for rapid detection of ZIKV. Our results revealed that the real-time assay is highly specific and sensitive in detection of ZIKV in cell samples. Importantly, the replication of ZIKV at different time points in infected cells could be rapidly monitored by the real-time RT-PCR assay. Specifically, the real-time RT-PCR showed acceptable performance in measurement of infectious ZIKV RNA. This assay could detect ZIKV at a titer as low as 1PFU/mL. The real-time RT-PCR assay could be a useful tool for further virology surveillance and diagnosis of ZIKV.

Neuroinflammation underlies the pathogenesis and progression of neurodegenerative diseases. 2׳-hydroxy-4,3׳,4׳,6׳-tetramethoxychalcone (HTMC) is a known chalcone derivative isolated from Chloranthus henryi with anti-inflammatory activities in BV2 macrophages. However, its pharmacological effects on microglial cells have not been demonstrated. To this end, we examined the effects of HTMC on lipopolysaccharide (LPS)-induced inflammatory responses in BV2 microglial cells. HTMC concentration-dependently inhibited LPS-induced expression of inflammatory enzymes including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), nitric oxide (NO) production, and the secretion of inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. In addition, HTMC inhibited reactive oxygen species (ROS) production by reducing NADPH oxidase (Nox) 2 and Nox4 expression. In addition, HTMC interfered LPS-induced c-Jun N-terminal kinase 1/2 (JNK) phosphorylation in a time- and concentration-dependent manner. By inhibiting phosphorylation and nuclear translocation of Jun, HTMC suppressed LPS-induced activator protein-1 (AP-1) activation. Taken together, our data indicate that HTMC suppresses inflammatory responses in LPS-stimulated BV2 microglial cells by modulating JNK-AP-1 and NADPH oxidases-ROS pathways. HTMC represents a promising therapeutic agent for neurodegenerative and related aging-associated diseases.

Transforming growth factor-β (TGF-β)/Smad signaling has been implicated in connective tissue growth factor (CTGF) expression in vascular smooth muscle cells (VSMC). Reactive oxygen species (ROS) are involved in activation of TGF-β/Smad signaling. However, detailed mechanisms underlying the process remain unclear. In present study, we demonstrated TGF-β1 strongly induced CTGF expression, Smad3 activation, NADPH oxidase 4 (Nox4) expression and increased ROS production in primary rat VSMC in vitro. NADPH oxidases inhibitor diphenylene iodonium (DPI) eliminated TGF-β1-induced CTGF expression and ROS generation. In addition, small-interfering RNA (siRNA) silencing of Smad3 or Nox4 significantly suppressed TGF-β1-mediated CTGF expression in VSMC. Furthermore, Nox4 silencing or inhibition eliminated TGF-β1-induced Smad3 activation and interaction between Nox4 and Smad3. In vivo studies further identified a positive correlation of Nox4 levels with Smad3 activation and CTGF expression in atherosclerotic arteries of patients and animal models. These data established that a novel mechanistic link of Nox4-dependent activation of Smad3 to increased TGF-β1-induced CTGF in the process of vascular remodeling, which suggested a new potential pathway for therapeutic interventions.