The role of mitogen-activated protein kinase-activated protein kinase 2 in the p38/TNF-alpha pathway of systemic and cutaneous inflammation

FRA1:c-JUN:HDAC1 complex down-regulates filaggrin expression upon TNFα and IFNγ stimulation in keratinocytes

Filaggrin (FLG), an essential structural protein for skin barrier function, is down-regulated under chronic inflammatory conditions, leading to disruption of the skin barrier. However, the detailed molecular mechanisms of how FLG changes in the context of chronic inflammation are poorly understood. Here, we identified the molecular mechanisms by which inflammatory cytokines inhibit FLG expression in the skin. We found that the AP1 response element within the -343/+25 of the FLG promoter was necessary for TNFα + IFNγ-induced down-regulation of FLG promoter activity. Using DNA affinity precipitation assay, we observed that AP1 subunit composition binding to the FLG promoter was altered from c-FOS:c-JUN (at the early time) to FRA1:c-JUN (at the late time) in response to TNFα + IFNγ stimulation. Knockdown of FRA1 or c-JUN abrogated TNFα + IFNγ-induced FLG suppression. Histone deacetylase (HDAC) 1 interacted with FRA1:c-JUN under TNFα + IFNγ stimulation. Knockdown of HDAC1 abrogated the inhibitory effect of TNFα + IFNγ on FLG expression. The altered expression of FLG, FRA1, c-JUN, and HDAC1 was confirmed in mouse models of 2,4-dinitrochlorobenzene-induced atopic dermatitis and imiquimod-induced psoriasis. Thus, the current study demonstrates that TNFα + IFNγ stimulation suppresses FLG expression by promoting the FRA1:c-JUN:HDAC1 complex. This study provides insight into future therapeutic strategies targeting the FRA1:c-JUN:HDAC1 complex to restore impaired FLG expression in chronic skin inflammation.

Molecular cloning, inducible expression and function analysis of Epinephelus coioides Sec6 response to SGIV infection

Exocyst complex component 3 Sec6 of mammals, one of the components of the exocyst complex, participates in numerous cellular functions, such as promoting cell migration and inhibiting apoptosis. In this study, the Sec6 was obtained from Epinephelus coioides, an economically important cultured fish. The full length of E. coioides Sec6 was 2655 bp including a 245 bp 5' UTR, a 154 bp 3' UTR, and a 2256 bp open reading frame (ORF) encoding 751 amino acids, with a molecular mass of 86.76 kDa and a theoretical pI of 5.57. Sec6 mRNA was detected in all the tissues examined, but the expression level is different in these tissues. Using fluorescence microscopy, Sec6 were distributed in both the nucleus and the cytoplasm. After SGIV infection, the expression of E. coioides Sec6 was significantly up-regulated in both trunk kidney and spleen response to Singapore grouper iridovirus (SGIV), an important pathogens of E. coioides. Sec6 could increase the SGIV-induced cytopathic effects (CPE), the expression of the SGIV genes VP19, LITAF, MCP, ICP18 and MCP, and the viral titers. Besides, E. coioides Sec6 significantly downregulated the promoter of NF-κB and AP-1, and inhibited the SGIV-induced apoptosis. The results demonstrated that E. coioides Sec6 might play important roles in SGIV infection.

Saikosaponin A and Saikosaponin C Reduce TNF-α-Induced TSLP Expression through Inhibition of MAPK-Mediated EGR1 Expression in HaCaT Keratinocytes

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases worldwide, characterized by intense pruritus and eczematous lesions. Aberrant expression of thymic stromal lymphopoietin (TSLP) in keratinocytes is associated with the pathogenesis of AD and is considered a therapeutic target for the treatment of this disease. Saikosaponin A (SSA) and saikosaponin C (SSC), identified from Radix Bupleuri, exert anti-inflammatory effects. However, the topical effects of SSA and SSC on chronic inflammatory skin diseases are unclear. In this study, we investigated the effects of SSA and SSC on TSLP suppression in an AD-like inflammatory environment. We observed that SSA and SSC suppressed tumor necrosis factor-α-induced TSLP expression by downregulating the expression of the transcription factor early growth response 1 (EGR1) via inhibition of the extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2, and p38 mitogen-activated protein kinase pathways. We also confirmed that topical application of SSA or SSC reduced AD-like skin lesions in BALB/c mice challenged with 2,4-dinitrochlorobenzene. Our findings suggest that suppression of EGR1-regulated TSLP expression in keratinocytes might be attributable to the anti-inflammatory effects of SSA and SSC in AD-like skin lesions.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Chrysin Inhibits TNFα-Induced TSLP Expression through Downregulation of EGR1 Expression in Keratinocytes

Thymic stromal lymphopoietin (TSLP) is an epithelial cell-derived cytokine that acts as a critical mediator in the pathogenesis of atopic dermatitis (AD). Various therapeutic agents that prevent TSLP function can efficiently relieve the clinical symptoms of AD. However, the downregulation of TSLP expression by therapeutic agents remains poorly understood. In this study, we investigated the mode of action of chrysin in TSLP suppression in an AD-like inflammatory environment. We observed that the transcription factor early growth response (EGR1) contributed to the tumor necrosis factor alpha (TNFα)-induced transcription of TSLP. Chrysin attenuated TNFα-induced TSLP expression by downregulating EGR1 expression in HaCaT keratinocytes. We also showed that the oral administration of chrysin improved AD-like skin lesions in the ear and neck of BALB/c mice challenged with 2,4-dinitrochlorobenzene. We also showed that chrysin suppressed the expression of EGR1 and TSLP by inhibiting the extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) 1/2 mitogen-activated protein kinase pathways. Collectively, the findings of this study suggest that chrysin improves AD-like skin lesions, at least in part, through the downregulation of the ERK1/2 or JNK1/2-EGR1-TSLP signaling axis in keratinocytes.

Chrysin Inhibits NF-κB-Dependent CCL5 Transcription by Targeting IκB Kinase in the Atopic Dermatitis-Like Inflammatory Microenvironment

Chrysin (5,7-dihydroxyflavone) is a natural polyphenolic compound that induces an anti-inflammatory response. In this study, we investigated the molecular mechanism underlying the chrysin-induced suppression of C-C motif chemokine ligand 5 (CCL5) gene expression in atopic dermatitis (AD)-like inflammatory microenvironment. We showed that chrysin inhibited CCL5 expression at the transcriptional level through the suppression of nuclear factor kappa B (NF-κB) in the inflammatory environment. Chrysin could bind to the ATP-binding pocket of the inhibitor of κB (IκB) kinase (IKK) and, subsequently, prevent IκB degradation and NF-κB activation. The clinical efficacy of chrysin in targeting IKK was evaluated in 2,4-dinitrochlorobenzene-induced skin lesions in BALB/c mice. Our results suggested that chrysin prevented CCL5 expression by targeting IKK to reduce the infiltration of mast cells to the inflammatory sites and at least partially attenuate the inflammatory responses. These findings suggested that chrysin might be useful as a platform for the design and synthesis of small-molecule IKK-targeting drugs for the treatment of chronic inflammatory diseases, such as AD.

MK2 Inhibition Induces p53-Dependent Senescence in Glioblastoma Cells

MAPK-activated protein kinase 2 (MK2) has diverse roles in cancer. In response to chemotherapy, MK2 inhibition is synthetically lethal to p53-deficiency. While TP53 deletion is rare in glioblastomas, these tumors often carry TP53 mutations. Here, we show that MK2 inhibition strongly attenuated glioblastoma cell proliferation through p53^wt stabilization and senescence. The senescence-inducing efficacy of MK2 inhibition was particularly strong when cells were co-treated with the standard-of-care temozolomide. However, MK2 inhibition also increased the stability of p53 mutants and enhanced the proliferation of p53-mutant stem cells. These observations reveal that in response to DNA damaging chemotherapy, targeting MK2 in p53-mutated cells produces a phenotype that is distinct from the p53-deficient phenotype. Thus, MK2 represents a novel drug target in 70% glioblastomas harboring intact TP53 gene. However, targeting MK2 in tumors with TP53 mutations may accelerate disease progression. These findings are highly relevant since TP53 mutations occur in over 50% of all cancers.

MAPKAPK2 plays a crucial role in the progression of head and neck squamous cell carcinoma by regulating transcript stability

Background

Head and neck squamous-cell carcinoma (HNSCC) ranks sixth among cancers worldwide. Though several molecular mechanisms of tumor initiation and progression of HNSCC are known, others remain unclear. Significance of p38/MAPKAPK2 (Mitogen-activated protein kinase-activated protein kinase-2) pathway in cell stress and inflammation is well established and its role in tumor development is being widely studied.

Methods

We have elucidated the role of MAPKAPK2 (MK2) in HNSCC pathogenesis using clinical tissue samples, MK2-knockdown (MK2_KD) cells and heterotropic xenograft mice model.

Results

In patient-derived tissue samples, we observed that MK2 is reproducibly overexpressed. Increased stability of cyclin-dependent kinase inhibitor 1B (p27), mitogen-activated protein kinase phosphatase-1 (MKP-1) transcripts and decreased half-life of tumor necrosis factor-alpha (TNF-α) and vascular endothelial growth factor (VEGF) transcripts in MK2_KD cells suggests that MK2 regulates their transcript stability. In vivo xenograft experiments established that knockdown of MK2 attenuates course of tumor progression in immunocompromised mice.

Conclusion

Altogether, MK2 is responsible for regulating the transcript stability and is functionally important to modulate HNSCC pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1167-2) contains supplementary material, which is available to authorized users.

Loss of MAPK-activated protein kinase 2 enables potent dendritic cell-driven anti-tumour T cell response

Maintaining dendritic cells (DC) in a state of dysfunction represents a key mechanism by which tumour cells evade recognition and elimination by the immune system. Limited knowledge about the intracellular mediators of DC dysfunction restricts success of therapies aimed at reactivating a DC-driven anti-tumour immune response. Using a cell type-specific murine knock-out model, we have identified MAPK-activated protein kinase 2 (MK2) as a major guardian of a suppressive DC phenotype in the melanoma tumour microenvironment. MK2 deletion in CD11c⁺ cells led to an expansion of stimulatory CD103⁺ DCs, mounting a potent CD8⁺ T cell response that resulted in elimination of highly aggressive B16-F10 tumours upon toll-like receptor (TLR) activation in the presence of tumour antigen. Moreover, tumour infiltration by suppressive myeloid cells was strongly diminished. These insights into the regulation of DC functionality reveal MK2 as a targetable pathway for DC-centred immunomodulatory cancer therapies.

Differential effect of p38 and MK2 kinase inhibitors on the inflammatory and toxicity biomarkers in vitro

BACKGROUND

Many inflammatory responses including chemotaxis, production of nitric oxide, and modulation of pro-inflammatory cytokines in immunological cells are mediated by p38MAPK. Due to its pivotal role, p38MAPK has been extensively explored as a molecular target for inhibition of chronic inflammation; however, it has not been successful so far due to serious toxicity issues. Among several downstream substrates of p38, mitogen-activated protein kinase-activated protein kinase 2 (MK2) has been reported to be a direct and essential downstream component in regulation of innate immune and inflammatory responses. Thus, in this study, we aimed to understand relative molecular differences between p38 and MK2 kinase inhibition in terms of a comparative anti-inflammatory potential along with molecular regulation of toxicity biomarkers such as Phospho c-Jun N-Terminal Kinase (pJNK), caspase-3, and hepatic enzyme levels in relevant human cells in vitro.

RESULTS

Both p38 and MK2 inhibitors attenuated lipopolysaccharide-induced pro-inflammatory biomarkers expression. In addition, both these kinase inhibitors inhibited release of Th1 and Th17 cytokines in phytohemagglutinin-induced cells with MK2 inhibitor showing a better potency for inhibition of Th1 cytokine release, interferon-γ. In the mechanistic differentiation studies, p38 inhibitors displayed an increase in pJNK and caspase-3 activity in U937 cells and elevation in aspartate transaminase enzyme in HepG2 cells, whereas MK2 inhibitor did not show such adverse toxic effects.

CONCLUSION

Taken together, inhibition of MK2 kinase can be a relatively preferred strategy as an anti-inflammatory therapy over direct inhibition of p38 kinase in p38MAPK pathway.

Bathing effects of east saline groundwater concentrates on allergic (atopic) dermatitis-like skin lesions induced by 2,4-dinitrochlorobenzene in hairless mice

In the present study, it was evaluated whether east saline groundwater concentration solution (ESGWc) exerted a favorable inhibitory effect on 2,4-dinitrochlorobenzene (DNCB)-induced allergic/atopic-like dermatitis (AD). AD was induced and boosted by sensitization with DNCB via topical application on the dorsal back skins. Mice with DNCB-induced AD were bathed in 100-, 200- and 400-fold diluted ESGWc. After 6 weeks bathing, changes to body weight, clinical skin severity scores, scratching behavior, serum total immunoglobulin (Ig)E levels, submandibular lymph node and spleen weights, splenic cytokine levels, skin cytokine mRNA expressions, antioxidant defense systems and superoxide anion productions were recorded to determine the effects of bathing on the histopathology of dorsal back skin tissues. All DNCB-induced mice demonstrated that the induction of AD through IgE-mediated hypersensitivities, oxidative stresses, activation of MMP and apoptosis of keratinocytes resulted in no significant differences in body weight between the different groups at each time point following initial sensitization. However, markers of DNCB-induced AD were significantly inhibited (P<0.05) in a concentration-dependent manner following bathing in all concentrations of ESGWc. The results obtained in the present study suggest that bathing in ESGWc may have favorable protective effects against DNCB-induced AD due to favorable systemic and local immunomodulatory effects, active cytoprotective anti-apoptotic effects, inhibitory effects of matrix metalloproteinase activity, and anti-inflammatory and antioxidative effects.

Pivotal Role of Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 in Inflammatory Pulmonary Diseases

Mitogen-activated protein kinase (MAPK)-activated protein kinase (MK2) is exclusively regulated by p38 MAPK in vivo. Upon activation of p38 MAPK, MK2 binds with p38 MAPK, leading to phosphorylation of TTP, Hsp27, Akt, and Cdc25 that are involved in regulation of various essential cellular functions. In this review, we discuss current knowledge about molecular mechanisms of MK2 in regulation of TNF-α production, NADPH oxidase activation, neutrophil migration, and DNA-damage-induced cell cycle arrest which are involved in the molecular pathogenesis of acute lung injury, pulmonary fibrosis, and non-small-cell lung cancer. Collectively current and emerging new information indicate that developing MK2 inhibitors and blocking MK2-mediated signal pathways are potential therapeutic strategies for treatment of inflammatory and fibrotic lung diseases and lung cancer.

The activation of EGFR promotes myocardial tumor necrosis factor-α production and cardiac failure in endotoxemia

To study the effect of EGFR activation on the generation of TNF-α and the occurrence of cardiac dysfuncetion during sepsis, PD168393 and erlotinib (both are EGFR inhibitors) were applied to decreased the production of TNF-α and phosphrylation of ERK1/2 and p38 induced by LPS in cardiomyocytes. These results were further proved by specifically knocked down the expression of EGFR in vitro. Both TAPI-1, a TNF-α converting enzyme (TACE) inhibitor, and TGF-α neutralizing antibody could inhibit the activation of EGFR and the generation of TNF-α mRNA after LPS treatment. The increase of TGF-α in response to LPS could also be suppressed by TAPI-1. On the other hand, exogenous TGF-α increased the expression of TNF-α mRNA and partially reversed the inhibitory effect of TAPI-1 on expression of TNF-α mRNA in response to LPS indicating that the transactivation of EGFR by LPS in cardiomyocytes needs the help of TACE and TGF-α. In endotoxemic mice, inhibition the activation of EGFR not only decreased TNF-α production in the myocardium but also improved left ventricular pump function and ameliorated cardiac dysfunction and ultimately improved survival rate. All these results provided a new insight of how EGFR regulation the production of TNF-α in cardiomyocytes and a potential new target for the treatment of cardiac dysfunction in sepsis.

Exercise preconditioning reduces neonatal incision surgery-induced enhanced hyperalgesia via inhibition of P38 mitogen-activated protein kinase and IL-1β, TNF-α release

Neonatal surgery leads to enhanced hyperalgesia to noxious stimulation in adulthood via a mechanism caused by enhanced phosphorylated (p)-p38 expression in microglia. We tested the effect of exercise on reducing enhanced hypersensitivity primed by neonatal incision surgery. Adult female Wistar rats, with or without neonatal incision surgery at postnatal day (P) 3, received right hind paw plantar incision surgery under anesthesia at P44. The rats performed wheel-running exercise from P22 to P41. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured and ipsilateral spinal cords were collected for protein quantification. For PWT and PWL, exercise reduced the pain index after incision surgery at P44 in rats with neonatal surgery (P<0.01). Western blots showed that exercise suppressed P-p38 expression relative to adult rats without neonatal surgery (P<0.05). Results of ELISA showed that exercise reduced IL-1β and TNF-α (P<0.05) concentration in the ipsilateral spinal cord. Exercise preconditioning is an effective approach to reducing enhanced adult hyperalgesia primed by neonatal surgery. The mechanism may be explained by exercise-induced inhibition of P-p38 activation and IL-1β, TNF-α release.

PI3K and ERK1/2 kinase inhibition potentiate protease inhibitor to attenuate allergen induced Th2 immune response in mouse

Proteases affect immune response by activating PI3K, ERK1/2 and p38 kinase. In present study, therapeutic effect of PI3K, ERK1/2 and p38 kinase inhibitor in combination with serine protease inhibitor was evaluated in cockroach extract (CE) induced airway inflammatory disease. Mice were sensitized on day 0, 7 and 14 and challenged on day 27, 28 and 29 with CE. Mice were given PI3K, ERK1/2 and the p38 kinase inhibitor (iPI3K, iERK1/2 and the ip38) alone or with serine protease inhibitor 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF), 1h before challenge. On day 30 airway resistance of mice were determined and euthanized to collect blood, BAL fluid and lung for analysis. CE immunized mice showed PI3K, ERK1/2 and p38 kinase activation, increased airway resistance, cellular infiltration, Th2 cytokines IgE and IgG1. AEBSF given to mice reduced the CE induced allergic response. AEBSF given in combination of iPI3K/iERK1/2 reduced cellular infiltration in lungs. Furthermore, iPI3K/iERK1/2 with AEBSF significantly reduced the CE induced Th2 cytokines in comparison to monotherapy of kinase inhibitor and AEBSF (P<0.05). The combination of iPI3K/iERK1/2 with AEBSF enhanced IL-12 level that could further provide a mean of Th2 reduction. Best effect in reduction of allergic response in mice was observed on administration of AEBSF with iPI3K. Conclusively, the combination of PI3K kinase inhibitor with AEBSF reduced allergen induced airway response and has therapeutic potential for add-on therapy in allergic airway disease.

The MAPK-Activated Kinase MK2 Attenuates Dendritic Cell-Mediated Th1 Differentiation and Autoimmune Encephalomyelitis

Dendritic cell (DC)-mediated inflammation induced via TLRs is promoted by MAPK-activated protein kinase (MK)-2, a substrate of p38 MAPK. In this study we show an opposing role of MK2, by which it consolidates immune regulatory functions in DCs through modulation of p38, ERK1/2-MAPK, and STAT3 signaling. During primary TLR/p38 signaling, MK2 mediates the inhibition of p38 activation and positively cross-regulates ERK1/2 activity, leading to a reduction of IL-12 and IL-1α/β secretion. Consequently, MK2 impairs secondary autocrine IL-1α signaling in DCs, which further decreases the IL-1α/p38 but increases the anti-inflammatory IL-10/STAT3 signaling route. Therefore, the blockade of MK2 activity enables human and murine DCs to strengthen proinflammatory effector mechanisms by promoting IL-1α-mediated Th1 effector functions in vitro. Furthermore, MK2-deficient DCs trigger Th1 differentiation and Ag-specific cytotoxicity in vivo. Finally, wild-type mice immunized with LPS in the presence of an MK2 inhibitor strongly accumulate Th1 cells in their lymph nodes. These observations correlate with a severe clinical course in DC-specific MK2 knockout mice compared with wild-type littermates upon induction of experimental autoimmune encephalitis. Our data suggest that MK2 exerts a profound anti-inflammatory effect that prevents DCs from prolonging excessive Th1 effector T cell functions and autoimmunity.

Bathing Effects of Various Seawaters on Allergic (Atopic) Dermatitis-Like Skin Lesions Induced by 2,4-Dinitrochlorobenzene in Hairless Mice

We evaluated the preventive effects of four types of seawater collected in Republic of Korea on hairless mice with 2,4-dinitrochlorobenzene- (DNCB-) induced allergic/atopic dermatitis (AD). The anti-inflammatory effects were evaluated by measuring tumor necrosis factor- (TNF-) α and interleukins (ILs). Glutathione (GSH), malondialdehyde (MDA), superoxide anion, and inducible nitric oxide synthase (iNOS) were measured to evaluate the antioxidant effects. Caspase-3 and poly (ADP-ribose) polymerase (PARP) were observed to measure the antiapoptotic effects; matrix metalloproteinase- (MMP-) 9 levels were also evaluated. Mice with AD had markedly higher clinical skin severity scores and scratching behaviors; higher TNF-α and ILs (1β, 10, 4, 5, and 13) levels; higher MDA, superoxide anion, caspase-3, PARP, and MMP-9 levels; and greater iNOS activity. However, the severity of AD was significantly decreased by bathing in seawaters, but it did not influence the dermal collagen depositions and skin tissue antioxidant defense systems. These results suggest that bathing in all four seawaters has protective effects against DNCB-induced AD through their favorable systemic and local immunomodulatory effects, active cytoprotective antiapoptotic effects, inhibitory effects of MMP activity and anti-inflammatory and antioxidative effects.

The effect of dexmedetomidine on inflammatory response of septic rats

Background

Some studies have demonstrated dexmedetomidine has anti-inflammatory effect on septic rats. However, the mechanism of how dexmedetomidine exerts these effects is still remained unknown. This study was designed to investigate the mechanism of how dexmedetomidine inhibits the production of inflammatory mediators in cecal ligation and puncturinduced septic rats.

Methods

48 Sprague-Dawley rats were randomly divided into six groups: sham-operated (sham) group, cecal ligation and puncture (CLP) group, dexmedetomidine 5 μg/kg (DEX5) group, dexmedetomidine 10 μg/kg (DEX10) group,dexmedetomidine + yohimbine (DEX10 + Yoh) group and yohimibine group (Yoh). Blood, bronchoalveolarlavage fluid (BALF) and lung tissues in each group were collected at six hours after dexmedetomidine or yohimbine treatment,. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in BALF and plasma were measured by enzyme-linked immunosorbent assay (ELISA). Toll-like receptor-4(TLR4) and myeloid differerntiation factor(MyD88) expression were measuredby quantitative PCR, and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation were determined by western blott.

Results

Compared with CLP group, dexmedetomidine significantly decreased not only the production of TNF-α and IL-6 both in plasma and BALF, but also inhibited the expression of TLR4 and MyD88 in mRNA level and the activation of ERK1/2 and NF-κB in the lung tissues of CLP-induced septic rats. All these effects could not be reversed by yohimibine.

Conclusions

Dexmedetomidine treatment can effectively reduce the generation of inflammatory mediators in the plasma and BALF of CLP-induced septic rats. These effects of dexmedetomidine rely on TLR4/MyD88/MAPK/ NF-κB signaling pathway and are independent of α₂-adrenoceptor.

Cytokine regulation by MAPK activated kinase 2 in keratinocytes exposed to sulfur mustard

Uncontrolled inflammation contributes to cutaneous damage following exposure to the warfare agent bis(2-chloroethyl) sulfide (sulfur mustard, SM). Activation of the p38 mitogen activated protein kinase (MAPK) precedes SM-induced cytokine secretion in normal human epidermal keratinocytes (NHEKs). This study examined the role of p38-regulated MAPK activated kinase 2 (MK2) during this process. Time course analysis studies using NHEK cells exposed to 200μM SM demonstrated rapid MK2 activation via phosphorylation that occurred within 15 min. p38 activation was necessary for MK2 phosphorylation as determined by studies using the p38 inhibitor SB203580. To compare the role of p38 and MK2 during SM-induced cytokine secretion, small interfering RNA (siRNA) targeting these proteins was utilized. TNF-α, IL-1β, IL-6 and IL-8 secretion was evaluated 24h postexposure, while mRNA changes were quantified after 8h. TNF-α, IL-6 and IL-8 up regulation at the protein and mRNA level was observed following SM exposure. IL-1β secretion was also elevated despite unchanged mRNA levels. p38 knockdown reduced SM-induced secretion of all the cytokines examined, whereas significant reduction in SM-induced cytokine secretion was only observed with TNF-α and IL-6 following MK2 knockdown. Our observations demonstrate potential activation of other p38 targets in addition to MK2 during SM-induced cytokine secretion.

Mitogen-activated protein kinase 2 regulates physiological and pathological bone turnover

The objective of this study was to investigate the role of the serine-threonine kinase mitogen-activated protein kinase 2 (MK2) in bone homeostasis. Primary bone cell cultures from MK2(+/+) and MK2(-/-) mice were assessed for osteoclast and osteoblast differentiation, bone resorption, and gene expression. Bone architecture of MK2(+/+) and MK2(-/-) mice was investigated by micro-computed tomography and histomorphometry. Ovariectomy was performed in MK2(+/+) and MK2(-/-) mice to assess the role of MK2 in postmenopausal bone loss. Osteoclastogenesis, bone resorption, and osteoclast gene expression were significantly impaired in monocytes from MK2(-/-) compared to MK2(+/+) mice. Mechanistically, loss of MK2 causes impaired DNA binding of c-fos and nuclear factor of activated T cells cytoplasmic 1 (NFATc1) to tartrate-resistant acid phosphatase (TRAP) and the calcitonin receptor gene promoter. In addition, MK2(-/-) mice showed an age-dependent increase in trabecular bone mass and cortical thickness, fewer osteoclasts, and lower markers of bone resorption than MK2(+/+) mice. Furthermore, MK2(-/-) mice were protected from ovariectomy-induced bone loss. Osteoblastogenesis and bone formation were unchanged in MK2(-/-) mice, whereas osteoblast expression of osteoprotegerin (OPG) and serum levels of OPG were higher in MK2(-/-) than in MK2(+/+) mice. Loss of MK2 effectively blocks bone resorption and prevents the development of postmenopausal bone loss. Small-molecule inhibitors of MK2 could thus emerge as highly effective tools to block bone resorption and to treat postmenopausal bone loss.

The Role of Mitogen-Activated Protein Kinase-Activated Protein Kinases (MAPKAPKs) in Inflammation

Mitogen-activated protein kinase (MAPK) pathways are implicated in several cellular processes including proliferation, differentiation, apoptosis, cell survival, cell motility, metabolism, stress response and inflammation. MAPK pathways transmit and convert a plethora of extracellular signals by three consecutive phosphorylation events involving a MAPK kinase kinase, a MAPK kinase, and a MAPK. In turn MAPKs phosphorylate substrates, including other protein kinases referred to as MAPK-activated protein kinases (MAPKAPKs). Eleven mammalian MAPKAPKs have been identified: ribosomal-S6-kinases (RSK1-4), mitogen- and stress-activated kinases (MSK1-2), MAPK-interacting kinases (MNK1-2), MAPKAPK-2 (MK2), MAPKAPK-3 (MK3), and MAPKAPK-5 (MK5). The role of these MAPKAPKs in inflammation will be reviewed.

Effects of topical application of Astragalus membranaceus on allergic dermatitis

Astragalus membranaceus (AM) is one of the most popular health-promoting herbs in East Asia, and has been used in traditional medicine for more than 2000 years. This study was performed to examine whether AM suppresses atopic dermatitis (AD)-like skin lesions in BALB/c mice. Seven-week-old female BALB/c mice were sensitized with 1-chloro-2,4-dinitrobenzene (DNCB) to induce allergic dermatitis. Skin sections were stained with hematoxylin and eosin (H&E) to assess epidermal and dermal hyperplasia, which were determined by measuring the thicknesses of the epidermis and dermis, respectively. The serum immunoglobulin G (IgE) concentration was quantified by enzyme-linked immunosorbent assay (ELISA). In addition, the levels of interleukins (IL)-4, -5, -6, and -13 and tissue necrosis factor (TNF)-α were measured in mouse serum. Significance was determined by one-way analysis of variance (ANOVA). Topical AM markedly improved the AD skin lesions in DNCB-induced mice. The AD skin lesions were significantly thinner in the AM treatment group compared with untreated controls, and the hyperkeratosis disappeared. Topical treatment of AM also restored nuclear factor-κB (NF-κB) expression. In addition, the serum IgE level was reduced. AM suppressed the expression of Th2 cytokines (IL-4, -5, -6, and -13) and significantly decreased the TNF-α level. AM is effective for treating AD by regulating cytokines. AM may be an alternative or complementary therapeutic option for treating patients with AD. More in-depth studies are necessary to clarify the mechanisms of AM.

The p38 MAPK Pathway in Rheumatoid Arthritis: A Sideways Look

The p38 mitogen-activated protein kinase (MAPK) signaling pathway has been strongly implicated in many of the processes that underlie the pathology of rheumatoid arthritis (RA). For many years it has been considered a promising target for development of new anti-inflammatory drugs with which to treat RA and other chronic immune-mediated inflammatory diseases. However, several recent clinical trials have concluded in a disappointing manner. Why is this so, if p38 MAPK clearly contributes to the excessive production of inflammatory mediators, the destruction of bone and cartilage? We argue that, to explain the apparent failure of p38 inhibitors in the rheumatology clinic, we need to understand better the complexities of the p38 pathway and its many levels of communication with other cellular signaling pathways. In this review we look at the p38 MAPK pathway from a slightly different perspective, emphasising its role in post-transcriptional rather than transcriptional control of gene expression, and its contribution to the off-phase rather than the on-phase of the inflammatory response.

Effect of DHU001, a Polyherbal Formula on Formalin-induced Paw Chronic Inflammation of Mice

The effect of DHU001, a mixed herbal formula consisted of 7 types aqueous extracts for various respiratory disorders were evaluated on the formalin-induced paw chronic inflammation in mice after oral administration. Mice were subaponeurotically injected in the left hind paw with 0.02 ml of 3.75% formalin, then subjected to 500, 250 and 125 mg/kg of DHU001 oral administration, once a day for 10 days during which then the hind-paw thickness and volume were measured daily. The paw wet-weight, histological profiles, histomorphometrical analyses and paw tumor necrosis factor (TNF)-α contents were conducted at termination. After two formalin treatments, a marked increase in the paw thickness and volume was detected in the formalin-injected control as compared with that in the intact control, plus at the time of sacrifice the paw wet-weights, paw TNF-α contents were also dramatically increased with severe chronic inflammation signs at histopathological observations. However, these formalin-induced chronic inflammatory changes were dramatically decreased by treatment of dexamethasone and all three different dosages of DHU001. DHU001 has favorable effects on formalin-induced chronic inflammation mediated by TNF-α suppression, and DHU001 may represent an alternative approach for the treatment of chronic inflammatory diseases.

The role of mitogen- and stress-activated protein kinase 1 and 2 in chronic skin inflammation in mice

Mitogen- and stress-activated protein kinase 1 and 2 (MSK1/2) are two kinases phosphorylated by both ERK1/2 and p38 MAPK. Recently, MSK1 and 2 have been reported to act as negative regulators of acute inflammation. In this study, we investigated the role of MSK1/2 in chronic skin inflammation using an oxazolone-induced allergic contact dermatitis model in MSK1/2 knockout mice and wild-type mice. MSK1/2 knockout mice were demonstrated to have significantly increased inflammation compared with wild-type mice. This was measured by an increased ear thickness, elevated infiltration of neutrophils in the skin and increased inflammatory histological changes. Furthermore, we found significantly elevated levels of the proinflammatory cytokines Tumor necrosis factor-α (TNF-α), IL-1β and IL-6 at both mRNA and protein levels in MSK1/2 knockout mice compared with wild-type mice after oxazolone treatment. In addition, the mRNA expression of the chemokine Thymus and activation regulated chemokine (TARC) was demonstrated to be significantly elevated in oxazolone-treated MSK1/2 knockout mice compared with wild-type mice. The increased expression of TARC was paralleled by increased infiltration of cells positive for the TARC receptor, CCR4, in the dermis of MSK1/2 knockout mice. Our results indicate that MSK1/2 are involved in the activation of feedback mechanisms that dampen oxazolone-induced skin inflammation.

Role of RGD-containing ligands in targeting cellular integrins: Applications for ovarian cancer virotherapy (Review)

The purpose of this article was to review the current strategies of targeted therapy to integrins and define the best course of future research in ovarian cancer targeting. Cell surface integrin targeting has been used as a strategy for targeted therapy of several diseases with some success. The combination of virotherapy and integrin-targeting shows promise as a method for targeting ovarian cancer. More specifically, targeting of ovarian cancer with integrin-directed adenoviruses may lead to therapy with fewer toxicities and side effects. This article offers a review of the benefits of integrin-specific targeted therapy for several diseases and proposes a unique anti-ovarian cancer strategy involving the combination of the above with virotherapy as a potential anti-ovarian cancer treatment.

MK2 signaling: lessons on tissue specificity in modulation of inflammation

MK2 is a promising candidate for treating inflammation. Mice deficient in MK2 were studied in models of inflammation to see whether MK2 could be a useful target in inflammatory skin disease. Surprisingly, MK2 played only a minor role in skin inflammation, indicating that modulation of cell signaling gives different results depending on the models of inflammation and target organs that are studied.