EV71 induces VCAM-1 expression via PDGF receptor, PI3-K/Akt, p38 MAPK, JNK and NF-κB in vascular smooth muscle cells

GRP78 recognizes EV-F 3D protein and activates NF-κB to repress virus replication by interacting with CHUK/IKBKB

Enteroviruses are the causative agents associated with several human and animal diseases, posing a significant threat to human and animal health. As one of the host immune defense strategies, innate immunity plays a crucial role in defending against invading pathogens, where the host utilizes a variety of mechanisms to inhibit or eliminate the pathogen. Here, we report a new strategy for the host to repress enterovirus replication by the 78 kDa glucose-regulated protein (GRP78), also known as heat shock protein family A member 5 (HSPA5). The GRP78 recognizes the EV-encoded RNA-dependent RNA polymerases (RdRPs) 3D protein and interacts with the nuclear factor kappa B kinase complex (CHUK) and subunit beta gene (IKBKB) to facilitate the phosphorylation and nuclear translocation of NF-κB, which induces the production of inflammatory factors and leads to a broad inhibition of enterovirus replication. These findings demonstrate a new role of GRP78 in regulating host innate immunity in response to viral infection and provide new insights into the mechanism underlying enterovirus replication and NF-κB activation.IMPORTANCEGRP78 is known as a molecular chaperone for protein folding and plays a critical role in maintaining protein folding and participating in cell proliferation, cell survival, apoptosis, and metabolism. However, the functions of GRP78 to participate in enterovirus genome replication and innate immune responses are rarely documented. In this study, we explored the functions of the EV-3D-interacting protein GRP78 and found that GRP78 inhibits enterovirus replication by activating NF-κB through binding to EV-F 3D and interacting with the NF-κB signaling molecules CHUK/IKBKB. This is the first report that GRP78 interacts with CHUK/IKBKB to activate the NF-κB signaling pathway, which leads to the expression of the proinflammatory cytokines and inhibition of enterovirus replication. These results demonstrate a unique mechanism of virus replication regulation by GRP78 and provide insights into the prevention and treatment of viral infections.

Recombinant Treponema pallidum protein Tp47 promotes the migration and adherence of THP-1 cells to human dermal vascular smooth muscle cells by inducing MCP-1 and ICAM-1 expression

Vascular inflammation is a complex and multifactorial pathophysiological process that plays a crucial role in all stages of syphilis and is responsible for tissue damage. Little is known about the interactions of infiltrating immunocytes with human dermal vascular smooth muscle cells (HDVSMCs) in arterioles during the immunopathogenesis of syphilis. The Treponema pallidum subsp. pallidum membrane protein Tp47 is considered a major inducer of inflammation initiation and development. In this study, we demonstrated that Tp47 promoted the migration and adhesion of THP-1 cells to HDVSMCs. Furthermore, Tp47 increased monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression levels in a dose- and time-dependent manner. The migration and adhesion of THP-1 cells to HDVSMCs were significantly suppressed by anti-MCP-1 and anti-ICAM-1 neutralizing antibodies, respectively. Further studies revealed that treatment of HDVSMCs with Tp47 activated the PI3K/Akt, p38 MAPK and NF-κB signalling pathways. Inhibition of PI3K/Akt, p38 MAPK and NF-κB suppressed the MCP-1 and ICAM-1 expression induced by Tp47. In addition, the migration and adhesion of THP-1 cells to Tp47-treated HDVSMCs were significantly decreased by pretreatment with PI3K/Akt, p38 MAPK and NF-κB inhibitors. These findings demonstrate that Tp47 promotes the migration and adherence of THP-1 cells to HDVSMCs by inducing MCP-1 and ICAM-1 expression, which is mediated by activation of the PI3K/Akt, p38 MAPK and NF-κB pathways. This study provides a novel potential therapeutic strategy for controlling the vascular inflammatory response in syphilis patients.

Resveratrol Attenuates Staphylococcus Aureus-Induced Monocyte Adhesion through Downregulating PDGFR/AP-1 Activation in Human Lung Epithelial Cells

Staphylococcus aureus (S. aureus) is a very common Gram-positive bacterium. It is widely distributed in air, soil, and water. S. aureus often causes septicemia and pneumonia in patients. In addition, it is considered to play a key role in mediating cell adhesion molecules upregulation. Resveratrol is a natural antioxidant with diverse biological effects, including the modulation of immune function, anti-inflammation, and cancer chemoprevention. In this study, we proved that S. aureus-upregulated vascular cell adhesion molecule-1 (VCAM-1) expression in human lung epithelial cells (HPAEpiCs) was inhibited by resveratrol. We also observed that resveratrol downregulated S. aureus-enhanced leukocyte count in bronchoalveolar lavage (BAL) fluid in mice. In HPAEpiCs, S. aureus stimulated c-Src, PDGFR, p38 MAPK, or JNK1/2 phosphorylation, which was inhibited by resveratrol. S. aureus induced the adhesion of THP-1 cells (a human monocytic cell line) to HPAEpiCs, which was also reduced by resveratrol. Finally, we found that S. aureus induced c-Src/PDGFR/p38 MAPK and JNK1/2-dependent c-Jun and ATF2 activation and in vivo binding of c-Jun and ATF2 to the VCAM-1 promoter, which were inhibited by resveratrol. Thus, resveratrol functions as a suppressor of S. aureus-induced inflammatory signaling, not only by inhibiting VCAM-1 expression but also by diminishing c-Src, PDGFR, JNK1/2, p38 MAPK, and AP-1 activation in HPAEpiCs.

Antiviral and Inflammatory Cellular Signaling Associated with Enterovirus 71 Infection

Enterovirus 71 (EV71) infection has become a major threat to global public health, especially in infants and young children. Epidemiological studies have indicated that EV71 infection is responsible for severe and even fatal cases of hand, foot, and mouth disease (HFMD). Accumulated evidence indicates that EV71 infection triggers a plethora of interactive signaling pathways, resulting in host immune evasion and inflammatory response. This review mainly covers the effects of EV71 infection on major antiviral and inflammatory cellular signal pathways. EV71 can activate cellular signaling networks including multiple cell surface and intracellular receptors, intracellular kinases, calcium flux, and transcription factors that regulate antiviral innate immunity and inflammatory response. Cellular signaling plays a critical role in the regulation of host innate immune and inflammatory pathogenesis. Elucidation of antiviral and inflammatory cellular signaling pathways initiated by EV71 will not only help uncover the potential mechanisms of EV71 infection-induced pathogenesis, but will also provide clues for the design of therapeutic strategies against EV71 infection.

PD169316, a specific p38 inhibitor, shows antiviral activity against Enterovirus71

Enterovirus71 (EV71) is the major causative agent of hand, foot and mouth disease, which threatens the health of infants and young children. The expression of inflammatory cytokines induced by this viral infection aggravate the illness. Here, we describe the anti-EV71 activity of a specific p38 inhibitor that regulates the p38-MAPK signaling pathway. PD169316 was specifically selected from a MAPK compound library due to its significant inhibitory effect on EV71 replication. PD169316 also reduced EV71-induced apoptosis. Animal experiments showed that PD169316 can dampen the replication of EV71, reduce tissue damage and inhibit the release of inflammatory cytokines, thereby alleviating the severe diseases caused by EV71 in suckling mice.

EV71 3D Protein Binds with NLRP3 and Enhances the Assembly of Inflammasome Complex

Activation of NLRP3 inflammasome is important for effective host defense against invading pathogen. Together with apoptosis-associated speck-like protein containing CARD domain (ASC), NLRP3 induces the cleavage of caspase-1 to facilitate the maturation of interleukin-1beta (IL-1β), an important pro-inflammatory cytokine. IL-1β subsequently plays critical roles in inflammatory responses by activating immune cells and inducing many secondary pro-inflammatory cytokines. Although the role of NLRP3 inflammasome in immune response is well defined, the mechanism underlying its assembly modulated by pathogen infection remains largely unknown. Here, we identified a novel mechanism by which enterovirus 71 (EV71) facilitates the assembly of NLRP3 inflammasome. Our results show that EV71 induces production and secretion of IL-1β in macrophages and peripheral blood mononuclear cells (PBMCs) through activation of NLRP3 inflammasome. EV71 replication and protein synthesis are required for NLRP3-mediated activation of IL-1β. Interestingly, EV71 3D protein, a RNA-dependent RNA polymerase (RdRp) was found to stimulate the activation of NLRP3 inflammasome, the cleavage of pro-caspase-1, and the release of IL-1β through direct binding to NLRP3. More importantly, 3D interacts with NLRP3 to facilitate the assembly of inflammasome complex by forming a 3D-NLRP3-ASC ring-like structure, resulting in the activation of IL-1β. These findings demonstrate a new role of 3D as an important player in the activation of inflammatory response, and identify a novel mechanism underlying the modulation of inflammasome assembly and function induced by pathogen invasion.

Intrinsic apoptosis and proinflammatory cytokines regulated in human astrocytes infected with enterovirus 71

Enterovirus 71 (EV71) has emerged as a clinically important neurotropic virus following poliovirus eradication. However, the mechanism of EV71-induced neurological manifestation remains largely unclear. In this study, we showed that human astrocytes were susceptible to EV71 and viral RNA was first detected at 12 h post-infection (p.i.), whilst viral proteins were detected at 36 h p.i. EV71-infected astrocytes underwent apoptosis, in which cytochrome c was released from mitochondria to the cytosol and caspase-9 was activated. Interestingly, caspase-2 and -8 were not cleaved or activated during the infection, whilst a selective inhibitor of caspase-9, Z-LEHD-FMK, blocked the cleavage of caspase-3 and -7, indicating that only the mitochondria-mediated intrinsic apoptotic pathway was activated in EV71-infected astrocytes. EV71 infection also induced proinflammatory cytokines, including IL-6, IL-8, CCL5 and IFN-γ-inducible protein (IP)-10 in astrocytes, which may play a critical role in EV71-induced neuroinflammation and neurological complications. By using inhibitors of mitogen-activated protein kinases (MAPKs), we demonstrated that the induction of the cytokines was mainly regulated by the MAPK p38 signalling pathway as a significant reduction of the cytokines was observed when treated with p38 inhibitors. This study demonstrated that human astrocytes were susceptible to EV71, and the infection led to intrinsic apoptosis and induction of p38-regulated proinflammatory cytokines. These findings further our understanding of the neuropathogenesis in severe cases of EV71 infection.

Etiology, pathogenesis, antivirals and vaccines of hand, foot, and mouth disease

Hand, foot, and mouth disease (HFMD), caused by enteroviruses, is a syndrome characterized by fever with vesicular eruptions mainly on the skin of the hands, feet, and oral cavity. HFMD primarily affects infants and young children. Although infection is usually self-limited, severe neurological complications in the central nervous system can present in some cases, which can lead to death. Widespread infection of HFMD across the Asia-Pacific region over the past two decades has made HFMD a major public health challenge, ranking first among the category C notifiable communicable diseases in China every year since 2008. This review summarizes our understanding of HFMD, focusing on the etiology and pathogenesis of the disease, as well as on progress toward antivirals and vaccines. The review also discusses the implications of these studies as they relate to the control and prevention of the disease.

Saururus chinensis (Lour.) Baill blocks enterovirus 71 infection by hijacking MEK1-ERK signaling pathway

The aerial parts of Saururus chinensis (Lour.) Baill are a Chinese herbal medicine used for the treatment of edema and inflammatory diseases. However, the effect of this medicine on enterovirus 71 (EV71) infection has not been explored. Previous studies showed that MEK1-ERK signal pathway was required for efficient replication of EV71 infection and inhibition of this signal pathway has been shown to suppress virus infection. Here we show that the water extract of S. chinensis (Lour.) Baill (SCB) significantly blocks EV71 infection by inhibiting the activation of MEK1-ERK signal pathway with an IC50 of 8.9μg/mL. SCB at 30 and 60 μg/mL blocked EV71-induced cytopathic effect (CPE) and production of infectious virion by 1.9 and 5.1 logs, respectively. Virucidal assay suggested that SCB had no virucidal activity against EV71 and probably exerted its effect by targeting multiple steps in EV71 infection. Knockdown of MEK1 but not MEK2 blocked EV71 replication. And SCB treatment inhibited the activation of MEK1-ERK signal during EV71 infection. Furthermore, we found that rutin at 200 μM, one of the major components of SCB, significantly suppressed EV71 induced CPE and inhibited viral replication in a dose dependent manner. Taken together, SCB inhibited EV71 infection by hijacking MEK1-ERK signal pathway and rutin was the responsible antiviral component of SCB.

Prediction of signaling pathways involved in enterovirus 71 infection by algorithm analysis based on miRNA profiles and their target genes

Enterovirus 71 (EV71) causes major outbreaks of hand, foot, and mouth disease. Host factors and signaling pathways exhibit important functions in the EV71 life cycle. We conducted algorithm analysis based on miRNA profiles and their target genes to identify the miRNAs and downstream signaling pathways involved in EV71 infection. The miRNA profiles of human rhabdomyosarcoma cells treated with interferon (IFN-)-α or IFN-γ were compared with those of cells infected with EV71. Genes targeted by differentially expressed miRNAs were identified and assigned to different signaling pathways according to public databases. The results showed that host miRNAs specifically responded to the viral infection and IFN treatment. Some miRNAs, including miR-124 and miR-491-3p, were regulated in opposite manners by the IFNs and EV71. Some signaling pathways regulated by both EV71 infection and IFN treatment were also predicted. These pathways included axon guidance, Wingless/Int1 (Wnt) signaling cascade, platelet-derived growth factor receptor (PDGFR)/PDGF, phosphatidylinositol 3-kinase (PI3K), Jun N-terminal kinase (JNK)/mitogen-activated protein kinase (MAPK), transforming growth factor-beta receptor (TGF-βR)/TGF-β, SMAD2/3, insulin/insulin-like growth factor (IGF), bone morphogenetic protein (BMP), CDC42, ERB1, hepatocyte growth factor receptor (c-Met), eukaryotic translation initiation factor 4E (eIF4E), protein kinase A (PKA), and IFN-γ pathways. The identified miRNA and downstream signaling pathways would help to elucidate the interaction between the virus and the host. The genomics method using algorithm analysis also provided a new way to investigate the host factors and signaling pathways critical for viral replication.

Activation of PI3K/Akt pathway limits JNK-mediated apoptosis during EV71 infection

Apoptosis is frequently induced to inhibit virus replication during infection of Enterovirus 71 (EV71). On the contrary, anti-apoptotic pathway, such as PI3K/Akt pathway, is simultaneously exploited by EV71 to accomplish the viral life cycle. The relationship by which EV71-induced apoptosis and PI3K/Akt signaling pathway remains to be elucidated. In this study, we demonstrated that EV71 infection altered Bax conformation and triggered its redistribution from the cytosol to mitochondria in RD cells. Subsequently, cytochrome c was released from mitochondria to cytosol. We also found that c-Jun NH2-terminal kinase (JNK) was activated during EV71 infection. The JNK specific inhibitor significantly inhibited Bax activation and cytochrome c release, suggesting that EV71-induced apoptosis was involved into a JNK-dependent manner. Meanwhile, EV71-induced Akt phosphorylation involved a PI3K-dependent mechanism. Inhibition of the PI3K/Akt pathway enhanced JNK phosphorylation and the JNK-mediated apoptosis upon EV71 infection. Moreover, PI3K/Akt pathway phosphorylated apoptosis signal-regulating kinase 1 (ASK1) and negatively regulated the ASK1 activity. Knockdown of ASK1 significantly decreased JNK phosphorylation, which implied that ASK1 phosphorylation by Akt inhibited ASK1-mediated JNK activation. Collectively, these data reveal that activation of the PI3K/Akt pathway limits JNK-mediated apoptosis by phosphorylating and inactivating ASK1 during EV71 infection.

Viral and host factors that contribute to pathogenicity of enterovirus 71

The single-stranded RNA virus enterovirus 71 (EV71), which belongs to the Picornaviridae family, has caused epidemics worldwide, particularly in the Asia–Pacific region. Most EV71 infections result in mild clinical symptoms, including herpangina and hand, foot and mouth disease. However, serious pathological complications have also been reported, especially for young children. The mechanisms of EV71 disease progression remain unclear. The pathogenesis of adverse clinical outcomes may relate to many factors, including cell tropism, cell death and host immune responses. This article reviews the recent advances in the identification of factors determining EV71 cell tropism, the associated mechanisms of viral infection-induced cell death and the interplay between EV71 and immunity.

The essential role of clathrin-mediated endocytosis in the infectious entry of human enterovirus 71

Little is currently known about the infectious entry process of human enterovirus 71 (HEV71) into host cells, which may represent potential anti-viral targeting sites. In this study a targeted small-interfering RNA (siRNA) screening platform assay was established and validated to identify and profile key cellular genes involved in processes of endocytosis, cytoskeletal dynamics, and endosomal trafficking essential for HEV71 infection. Screen evaluation was conducted via the expression of well characterized dominant-negative mutants, bioimaging studies (double-labeled immunofluorescence assays, transmission electron microscopy analysis), secondary siRNA-based dosage dependence studies, and drug inhibition assays. The infectious entry of HEV71 into rhabdomyosarcoma cells was shown to be significantly inhibited by siRNAs targeting genes associated with clathrin-mediated endocytosis (CME) that include AP2A1, ARRB1, CLTC, CLTCL1, SYNJ1, ARPC5, PAK1, ROCK1, and WASF1. The functional role of CME was verified by the observation of strong co-localization between HEV71 particles and clathrin as well as dose-dependent inhibition of HEV71 infection upon siRNA knockdown of CME-associated genes. HEV71 entry by CME was further confirmed via inhibition by dominant-negative EPS15 mutants and treatment of CME drug inhibitors, with more than 80% inhibition observed at 20 μm chlorpromazine. Furthermore, HEV71 infection was shown to be sensitive to the disruption of human genes in regulating early to late endosomal trafficking as well as endosomal acidic pH. The identification of clathrin-mediated endocytosis as the entry pathway for HEV71 infection of susceptible host cells contributes to a better understanding of HEV71 pathogenesis and enables future development of anti-viral strategies against HEV71 infection.

Neural pathogenesis of enterovirus 71 infection

Enterovirus 71 (EV71) is a neurotropic pathogen that can cause severe neural diseases and complications on infected patients. Clinical observations showed that EV71-induced immune responses may be associated with virus induced neurogenic pulmonary edema. Here reviewed studies that discovered several host molecules as potential factors for EV71 virulence.

Involvement of MAPKs and NF-kappaB in tumor necrosis factor alpha-induced vascular cell adhesion molecule 1 expression in human rheumatoid arthritis synovial fibroblasts

OBJECTIVE

To investigate the roles of MAPKs and NF-kappaB in tumor necrosis factor alpha (TNFalpha)-induced expression of vascular cell adhesion molecule 1 (VCAM-1) in human rheumatoid arthritis synovial fibroblasts (RASFs).

METHODS

Human RASFs were isolated from synovial tissue obtained from patients with RA who underwent knee or hip surgery. The involvement of MAPKs and NF-kappaB in TNFalpha-induced VCAM-1 expression was investigated using pharmacologic inhibitors and transfection with short hairpin RNA (shRNA) and measured using Western blot, reverse transcriptase-polymerase chain reaction, and gene promoter assay. NF-kappaB translocation was determined by Western blot and immunofluorescence staining. The functional activity of VCAM-1 was evaluated by lymphocyte adhesion assay.

RESULTS

TNFalpha-induced VCAM-1 expression, phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK, and translocation of NF-kappaB were attenuated by the inhibitors of MEK-1/2 (U0126), p38 (SB202190), JNK (SP600125), and NF-kappaB (helenalin) or by transfection with their respective shRNA. TNFalpha-stimulated translocation of NF-kappaB into the nucleus and NF-kappaB promoter activity were blocked by Bay11-7082, but not by U0126, SB202190, or SP600125. VCAM-1 promoter activity was enhanced by TNFalpha in RASFs transfected with VCAM-1-Luc, and this promoter activity was inhibited by Bay11-7082, U0126, SB202190, and SP600125. Moreover, up-regulation of VCAM-1 increased the adhesion of lymphocytes to the RASF monolayer, and this adhesion was attenuated by pretreatment with helenalin, U0126, SP600125, or SB202190 prior to exposure to TNFalpha or by anti-VCAM-1 antibody before the addition of lymphocytes.

CONCLUSION

In RASFs, TNFalpha-induced VCAM-1 expression is mediated through activation of the p42/p44 MAPK, p38 MAPK, JNK, and NF-kappaB pathways. These results provide new insights into the mechanisms underlying cytokine-initiated joint inflammation in RA and may inspire new targeted therapeutic approaches.

Signaling pathways involved in liver injury and regeneration in rabbit hemorrhagic disease, an animal model of virally-induced fulminant hepatic failure

Management of fulminant hepatic failure (FHF) continues to be one challenging problem, and experimental animal models resembling its clinical conditions are still needed. Rabbit hemorrhagic disease (RHD) fullfils many requirements of an animal model of FHF. This work investigated changes in MAPK, NF-kappaB, AP-1 and STAT pathways during RHD-induced liver injury. Rabbits were infected with 2 x 10(4) hemagglutination units of an RHD virus isolate. Apoptosis was documented by the presence of caspase-3 activity and substantial PARP proteolysis at 36 and 48 h postinfection (pi). Infection induced a marked and maintained expression of TNF-alpha from 12 h pi, while there was only a transitory increase in IL-6 expression. Expression of phosphorylated (p)-JNK, p-p38 and p-ERK1/2 was significantly elevated at 12 h pi. At 48 h pi p-JNK expression was maintained at a maximum level, while that of p-p38 returned to normality and there was no p-ERK1/2 expression. Activation of NF-kappaB and AP-1 and increased expression of VCAM-1 and COX-2 were observed. No significant changes were detected in activation of STAT1 and STAT3, while SOCS3 expression increased significantly. The current findings suggest that activation of JNK is an essential component in liver injury mediated by the RHD virus and that lack of activation of STAT3, probably mediated by SOCS3 over-expression, would contribute to the inhibition of the regenerative response. Data show the presence of molecular mechanisms contributing to liver damage and the lack of regeneration and they support the usefulness of this model to investigate novel therapeutical modalities in FHF.

Inhibitory effect of ETB receptor on Na(+)-K(+) ATPase activity by extracellular Ca(2+) entry and Ca(2+) release from the endoplasmic reticulum in renal proximal tubule cells

The kidney is important in the long-term regulation of blood pressure and sodium homeostasis. Stimulation of ETB receptors in the kidney increases sodium excretion, in part, by decreasing sodium transport in the medullary thick ascending limb of Henle and in collecting duct. However, the role of ETB receptor on Na(+)-K(+) ATPase activity in renal proximal tubule (RPT) cells is not well defined. The purpose of this study is to test the hypothesis that ETB receptor inhibits Na(+)-K(+) ATPase activity in rat RPT cells, and investigate the mechanism(s) by which such an action is produced. In RPT cells from Wistar-Kyoto rats, stimulation of ETB receptors by the ETB receptor agonist, BQ3020, decreased Na(+)-K(+) ATPase activity, determined by ATP hydrolysis (control=0.38+/-0.02, BQ3020=0.26+/-0.03, BQ788=0.40+/-0.06, BQ3020+BQ788=0.37+/-0.04, n=5, P<0.01). The ETB receptor-mediated inhibition of Na(+)-K(+) ATPase activity was dependent on an increase in intracellular calcium, because this effect was abrogated by a chelator of intracellular-free calcium (BAPTA-AM; 5 x 10(-3) M 15 min(-1)), Ca(2+) channel blocker (10(-6) M 15 min(-1) nicardipine) and PI3 kinase inhibitor (10(-7) M per wortmannin). An inositol 1,4,5-trisphosphate (IP3) receptor blocker (2-aminoethyl diphenyl borate; 10(-4) M 15 min(-1)) also blocked the inhibitory effect of the ETB receptor on Na(+)-K(+)ATPase activity (control=0.39+/-0.06, BQ3020=0.25+/-0.01, 2-APB=0.35+/-0.05, BQ3020+ 2-APB=0.35+/-0.06, n=4, P<0.01). The calcium channel agonist (BAY-K8644; 10(-6) M 15 min(-1)) inhibited Na(+)-K(+) ATPase activity, an effect that was blocked by a phosphatidylinositol-3 kinase inhibitor (10(-7) M 15 min(-1) wortmannin). In rat RPT cells, activation of the ETB receptor inhibits Na(+)-K(+) ATPase activity by facilitating extracellular Ca(2+) entry and Ca(2+) release from endoplasmic reticulum.

Chondroitin sulfate extracted from ascidian tunic inhibits phorbol ester-induced expression of Inflammatory factors VCAM-1 and COX-2 by blocking NF-kappaB activation in mouse skin

Inflammatory factors are known to play a key role in promoting tumorigenesis; therefore, it is a promising strategy to inhibit the inflammation for cancer prevention. The current study was performed to investigate the potential effects of chondroitin sulfate (CS) extracted from ascidian tunic on the expression of inflammatory factors induced by treatment with 12- O-tetradecanoylphorbol-13-acetate (TPA) and to elucidate the underlying molecular mechanism of CS action in mouse skin inflammation. TPA was topically applied to the shaven backs of ICR mice with or without CS (1 or 2 mg) for 4 h. The results demonstrated that CS suppressed TPA-induced edema and reduced the expression of cyclooxygenase-2, vascular cell adhesion molecule-1, and Akt signaling in mouse skin. These studies suggest that CS from ascidian tunic may be developed as an effective natural anti-inflammatory agent.

Early phosphatidylinositol 3-kinase/Akt pathway activation limits poliovirus-induced JNK-mediated cell death

Poliovirus (PV)-induced apoptosis seems to play a major role in tissue injury in the central nervous system (CNS). We have previously shown that this process involves PV-induced Bax-dependent mitochondrial dysfunction mediated by early JNK activation in IMR5 neuroblastoma cells. We showed here that PV simultaneously activates the phosphatidylinositol 3-kinase (PI3K)/Akt survival signaling pathway in these cells, limiting the extent of JNK activation and thereby cell death. JNK inhibition is associated with PI3K-dependent negative regulation of the apoptosis signal-regulating kinase 1, which acts upstream from JNK in PV-infected IMR5 cells. In poliomyelitis, this survival pathway may limit the spread of PV-induced damage in the CNS.