Children's post-burn scars in Mongolia.

This study aimed to identify some risk factors for post-burn scarring in children aged 0-18 years. One hundred and eighty two participants were involved in this cohort study. Under the age of 18 who were admitted to the Department of Burn Reconstructive Surgery with a diagnosis of upper and lower extremity burns were followed for 6 months. A total of 182 participants (62.1% male, and 37.9% female participants) enrolled in this study. Age ranged from 1 to 17 and the average age was 3.95 ± 3.35. The degree of burn and the anatomical location of the burn had a statistically significant effect on the development of hypertrophic scars. The length of the patient's hospitalisation days and the area of ​​the burn were statistically correlated with wound healing (P = 000, P = .074). For example, the average length of hospitalisation days was 8 ± 5 days in the hypertrophic scars group of patients, and in the group with normal scars, average bed days were 6 ± 3 days (P = .000). Grade IIIb burns increased the risk of hypertrophic scar development by 4.9 times and grade IV burns increased it by 2.5 times. In addition, when the area of burns was 11% or more, the risk of hypertrophic scar development was increased by 58.8%. In the case of wound swab infection, the risk of hypertrophic scar development was 12.4% higher (B = 1.124, 95 EI = 0.55; 2.28, P = .748). Participants' age, burn area and degree of burn are statistically significant risk factors for post-burn scarring in children aged 0-18 years.

Sendai virus V protein decreases nitric oxide production by inhibiting RIG-I signaling in infected RAW264.7 macrophages.

Sendai virus V protein is a known antagonist of RIG-I-like receptors (RLRs) RIG-I and MDA5, which activate transcription factors IRF3, leading to activation of ISGF3 and NF-κB. These transcription factors are known activators of inducible NO synthase (iNOS) and increase the production of nitric oxide (NO). By inhibiting ISGF3 and NF-κB, the V protein acts as an indirect negative regulator of iNOS and NO. Here we report that the V gene knockout Sendai virus [SeV V(-)] markedly enhanced iNOS expression and subsequent NO production in infected macrophages compared to wild-type SeV. The knockout of RIG-I in cells inhibited SeV V(-)-induced iNOS expression and subsequent NO production. To understand the underlying mechanism of the V protein-mediated negative regulation of iNOS activation, we transfected HEK293T cells with RIG-I and the RIG-I regulatory protein TRIM25. Our results demonstrated that the V protein inhibited iNOS activation via the RIG-I/TRIM25 pathway. Moreover, the V protein inhibited TRIM25-mediated K63-linked ubiquitination of RIG-I, as well as its CARD-dependent interaction with mitochondrial antiviral signaling (MAVS) molecules. These results suggest that the V protein downregulates iNOS activation and inhibits NO production by preventing the RIG-I-MAVS interaction, possibly through its effect on the ubiquitination status of RIG-I.

Sendai virus C protein limits NO production in infected RAW264.7 macrophages.

To suppress virus multiplication, infected macrophages produce NO. However, it remains unclear how infecting viruses then overcome NO challenge. In the present study, we report the effects of accessory protein C from Sendai virus (SeV), a prototypical paramyxovirus, on NO output. We found that in RAW264.7 murine macrophages, a mutant SeV without C protein (4C(-)) significantly enhanced inducible NO synthase (iNOS) expression and subsequent NO production compared to wild type SeV (wtSeV). SeV 4C(-) infection caused marked production of IFN-ß, which is involved in induction of iNOS expression via the JAK-STAT pathway. Addition of anti-IFN-ß Ab, however, resulted in only marginal suppression of NO production. In contrast, NF-κB, a primarily important factor for transcription of the iNOS gene, was also activated by 4C(-) infection but not wtSeV infection. Induction of NO production and iNOS expression by 4C(-) was significantly suppressed in cells constitutively expressing influenza virus NS1 protein that can sequester double-stranded (ds)RNA, which triggers activation of signaling pathways leading to activation of NF-κB and IRF3. Therefore, C protein appears to suppress NF-κB activation to inhibit iNOS expression and subsequent NO production, possibly by limiting dsRNA generation in the context of viral infection.

Irbesartan attenuates production of high-mobility group box 1 in response to lipopolysaccharide via downregulation of interferon-ß production.

High-mobility group box 1 (HMGB1) is suggested to participate in development of local and systemic inflammatory disorders. Irbesartan (IRB), an angiotensin II type1 receptor blocker, is widely used for treatment of hypertension, especially in patients with diabetic nephropathy. The effect of IRB on lipopolysaccharide (LPS)-induced HMGB1 and nitric oxide (NO) production was examined using RAW 264.7 macrophage-like cells. IRB inhibited LPS-induced HMGB1 production. IRB also reduced LPS-induced expression of an inducible NO synthase, and inhibited LPS-induced NO production. The expression levels of IFN-ß protein and mRNA, which is a key molecule in MyD88-independent pathway of LPS signaling, were exclusively inhibited by IRB. Peroxisome proliferator-activated receptor-γ and angiotensin II type 1 receptor were not involved in the inhibitory action of IRB on LPS-induced HMGB1 and NO production. Collectively, IRB was suggested to inhibit LPS-induced HMGB1 production via downregulation of IFN-ß production in the MyD88-independent pathway.

Lipopolysaccharide downregulates the expression of p53 through activation of MDM2 and enhances activation of nuclear factor-kappa B.

The effect of lipopolysaccharide (LPS) on the expression of p53 protein in RAW 264.7 macrophage cells was examined. LPS downregulated the expression of p53 protein 4-24 h after the stimulation. LPS-induced p53 inhibition was restored with pharmacological inhibitors of c-jun N-terminal kinase (JNK) and phosphatidylinositol 3-kinase (PI3K). It was also restored by inhibitors of MDM2 activation and proteasome. LPS-induced p53 inhibition corresponded to activation of MDM2. LPS-induced MDM2 activation was prevented by inhibitors of JNK and PI3K. The expression of p65 NF-κB at a late stage after LPS stimulation was downregulated in the presence of a MDM2 inhibitor. Nutlin-3 as a MDM2 inhibitor reduced LPS-induced production of nitric oxide but not tumor necrosis factor-α. Administration of LPS into mice downregulated the in vivo expression of p53 in the livers. Taken together, LPS was suggested to downregulate the expression of p53 via activation of MDM2 and enhance the activation of NF-κB at a late stage.

Involvement of redox balance in in vitro osteoclast formation of RAW 264.7 macrophage cells in response to LPS.

Here we report that LPS induces osteoclast (OC) formation in murine RAW 264.7 macrophage cells in RPMI-1640 medium but not in α-minimum essential medium (α-MEM) as the original culture medium. LPS-induced OC formation in both media was examined to clarify the differential response. Receptor activator of NF-κB ligand induced OC formation in either α-MEM or RPMI-1640 medium. However, LPS-induced OC formation in RAW 264.7 cells maintained in RPMI-1640 medium, but not α-MEM, which was also supported by mouse bone marrow-derived macrophages, although they were less sensitive to LPS than RAW 264.7 cells. LPS augmented the expression of nuclear factor of activated T-cells (NFATc1) as a key transcription factor of osteoclastogenesis in cells maintained in RPMI-1640 medium, but reduced it in cells maintained in α-MEM. A high concentration of LPS was cytotoxic against cells maintained in α-MEM. Glutathione exclusively present in RPMI-1640 medium prevented LPS-induced cell death in α-MEM and augmented LPS-induced NFATc1 expression, followed by enhanced LPS-induced OC formation. LPS induced higher generation of reactive oxygen species in α-MEM than RPMI-1640 medium. An antioxidant enhanced LPS-induced OC formation, whereas a pro-oxidant reduced it. Taken together, redox balance in the culture condition was suggested to regulate in vitro LPS-induced OC formation.

Sendai virus C protein inhibits lipopolysaccharide-induced nitric oxide production through impairing interferon-ß signaling.

The effect of Sendai virus (SeV) C protein on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was examined using RAW 264.7 macrophage cells. Infection of SeV inhibited LPS-induced NO production via downregulating the expression of an inducible NO synthase protein (iNOS). On the other hand, C gene-knockout 4C(-) SeV inhibited neither NO production nor iNOS expression. Wild type and 4C(-) SeV did not affect LPS-induced production of tumor necrosis factor-α and interleukin-6, and further LPS-induced activation of nuclear factor (NF)-κB and mitogen-activated protein kinases. Although wild type and 4C(-) SeV did not inhibit LPS-induced interferon (IFN)-ß production, wild type SeV but not 4C(-) SeV inhibited the activation of STAT1/2 in the IFN-ß signaling. SeV C protein inhibited LPS-induced iNOS expression and NO production. C protein inhibited the promotor activation of IFN-ß and IFN-sensitive response element (ISRE) in response to LPS whereas the C mutant protein CF170S, which lacks the ability to block the STAT activation, did not inhibit it. Taken together, SeV C protein was suggested to inhibit LPS-induced NO production through impairing IFN-ß signaling.

Spironolactone inhibits production of proinflammatory mediators in response to lipopolysaccharide via inactivation of nuclear factor-κB.

The effect of spironolactone (SPIR) on lipopolysaccharide (LPS)-induced production of proinflammatory mediators was examined using RAW 264.7 macrophage-like cells and mouse peritoneal macrophages. SPIR significantly inhibited LPS-induced production of nitric oxide (NO), tumor necrosis factor-α and prostaglandin E2. The inhibition was not mediated by cell death. SPIR reduced the expression of an inducible NO synthase mRNA in response to LPS. SPIR significantly inhibited phosphorylation of p65 nuclear factor (NF)-κB in response to LPS. Furthermore, SPIR inhibited phosphorylation of IκB kinase (IKK) as an upstream molecule of NF-κB in response to LPS. LPS did not induce the production of aldosterone in RAW 264.7 cells. Taken together, SPIR is suggested to inhibit LPS-induced proinflammatory mediators via inactivation of IKK/NF-κB in LPS signaling.

Inhibition of receptor activator of nuclear factor-κB ligand- or lipopolysaccharide-induced osteoclast formation by conophylline through downregulation of CREB.

The effect of conophylline (CNP) on the receptor activator of nuclear factor-κB ligand (RANKL) or lipopolysaccharide (LPS)-induced osteoclast formation was studied in vitro using bone marrow-derived macrophages (BMMs) or the mouse macrophage-like cell line RAW 264.7. CNP inhibited RANKL-induced formation of osteoclasts identified as tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in a culture of BMMs. It also inhibited RANKL- or LPS-induced osteoclast formation in RAW 264.7 cells. CNP lowered the osteoclast maturation markers such as calcitonin receptor, MMP9 and cathepsin K in BMMs, suggesting that CNP would inhibit the process of osteoclast differentiation. CNP inhibited the RANKL-induced expressions of c-Fos and nuclear factor of activated T cells (NFATc1), key transcription factors for osteoclastogenesis. On the other hand, CNP did not inhibit the signaling pathway of NF-κB and mitogen-activated protein kinases (MAPKs) in RANKL-stimulated BMMs. Interestingly, CNP inhibited RANKL-induced CREB activation that can mediate c-Fos and NFATc1. CNP also inhibited RANKL- or LPS-induced CREB, c-Fos and NFATc1 activation in RAW 264.7 cells. We have previously found that CNP directly binds to ADP-ribosylation-like factor-6 interacting protein (ARL6ip), although its role in osteoclastogenesis is not clear. Gene knockdown of ARL6ip by siRNA inhibited RANKL-induced c-Fos expression, suggesting that inactivation of ARL6ip may be involved in an inhibitory effect of CNP. Taken together, CNP was shown to inhibit osteoclast formation possibly via CREB inactivation following a decrease in c-Fos and NFATc1 expression.

A novel mechanism for inhibition of lipopolysaccharide-induced proinflammatory cytokine production by valproic acid.

The inhibitory effect of valproic acid (VPA) on lipopolysaccharide (LPS)-induced inflammatory response was studied by using mouse RAW 264.7 macrophage-like cells. VPA pretreatment attenuated LPS-induced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt, but not nuclear factor (NF)-κB and mitogen-activated protein kinases. VPA reduced phosphorylation of MDM2, an ubiquitin ligase and then prevented LPS-induced p53 degradation, followed by enhanced p53 expression. Moreover, p53 small interfering RNA (siRNA) abolished the inhibitory action of VPA on LPS-induced NF-κB p65 transcriptional activation and further LPS-induced tumor necrosis factor (TNF)-α and interleukin (IL)-6 production. VPA prevented LPS-induced degradation of phosphatase and tensin homologue deleted on chromosome ten (PTEN) and up-regulated the PTEN expression. Taken together, VPA was suggested to down-regulate LPS-induced NF-κB-dependent transcriptional activity via impaired PI3K/Akt/MDM2 activation and enhanced p53 expression. A detailed mechanism for inhibition of LPS-induced inflammatory response by VPA is discussed.

Lipopolysaccharide impairs insulin sensitivity via activation of phosphoinositide 3-kinase in adipocytes.

The effect of lipopolysaccharide (LPS) on insulin sensitivity in adipocytes were examined by using differentiated 3T3-L1 adipocytes. Insulin-mediated activation of insulin receptor substrate (IRS) 1/2 was inhibited in LPS-pretreated adipocytes and IRS1/2-mediated Akt activation was also attenuated in those cells. LPS inhibited activation of glycogen synthase kinase 3 as a negative regulator of glycogenesis and impaired the glycogen synthesis in response to insulin. LPS-induced activation of phosphoinositide 3-kinase (PI3K) in adipocytes. Involvement of suppressor of cytokine signaling 3 (SOCS3) in LPS-induced IRS1/2 inhibition was excluded. Considering that both insulin and LPS were able to activate the PI3K/Akt signaling pathway, LPS was suggested to impair insulin sensitivity of adipocytes through down-regulating insulin-mediated PI3K/Akt activation.

Augmentation of LPS-induced vascular endothelial cell growth factor production in macrophages by transforming growth factor-ß1.

The effect of LPS on the production of vascular endothelial growth factor (VEGF) was examined using RAW 264.7 macrophage cells. LPS induced VEGF production in RAW 264.7 cells and mouse peritoneal cells. LPS induced VEGF production via the expression of hypoxia inducible factor-1α and LPS-induced VEGF production was dependent on the activation of p38 MAPK and NF-κB activation· Transforming growth factor (TGF)-ß1 augmented LPS-induced VEGF production, although TGF-ß1 alone did not induce VEGF production. The augmentation of LPS-induced VEGF production by TGF-ß1 was inhibited by a p38 MAPK inhibitor and was correlated with the phosphorylation of Smad3. The enhancing effect of TGF-ß1 on LPS-induced VEGF production was observed in vivo in the skin lesions of mice receiving a subcutaneous injection of LPS. Taken together, it is suggested that LPS induced the VEGF production in macrophages and that it was augmented by TGF-ß1 in vitro and in vivo.

Immunological role of prostaglandin E2 production in mouse auditory cells in response to LPS.

The effect of LPS on the production of prostaglandin E2 (PGE2) in mouse HEI-OC1 auditory cells was examined. HEI-OC1 auditory cells constitutively produce a small amount of PGE2. LPS augmented the PGE2 production via enhanced cyclooxygenase 2 (COX2) expression. LPS-induced augmentation of COX2 expression was dependent on up-regulation of COX2 mRNA expression. LPS induced the production of TNF-α, but not IL-1ß· An anti-TNF-α neutralizing Ab significantly inhibited PGE2 production and COX2 mRNA expression in response to LPS. LPS-induced PGE2 production was prevented by a series of pharmacological signaling inhibitors to NF-κB and MAPKs. Pam3CSK4 as a TLR2 ligand, as well as LPS as a TLR4 ligand, augmented the PGE2 production. However, poly I:C as a TLR3 ligand, imiquimod as a TLR7 ligand and CpG DNA as a TLR9 ligand did not augment it. HEI-OC1 cells expressed TLR2, TLR4 and TLR9, but not TLR3 or TLR7. The putative role of LPS-induced PGE2 production in auditory cells is discussed.

Involvement of oncogenic protein ß-catenin in LPS-induced cytotoxicity in mouse mononuclear leukemia RAW 264.7 cells.

A toll-like receptor 4 (TLR-4) ligand, lipopolysaccharide (LPS) not only activates expression and secretion of inflammatory cytokines, but it also often shows toxicity in monocytes. Whether an oncogenic protein, ß-catenin, is positively involved in LPS-induced cytotoxicity in a mouse leukemic monocyte cell line, RAW 264.7, was examined. TWS119, a GSK-3ß inhibitor, increased LPS-induced ß-catenin accumulation in the nucleus and augmented LPS-induced cytotoxicity. Cardamonin, a ß-catenin inhibitor, inhibited LPS-induced ß-catenin accumulation in the nucleus and reduced LPS-induced cytotoxicity. To confirm that ß-catenin is involved in LPS-induced cytotoxicity, silencing of ß-catenin expression by siRNA was carried out. The results were that knockdown of ß-catenin reduced LPS-induced cytotoxicity. Interestingly, Cardamonin treatment or ß-catenin silencing reduced LPS-induced endoplasmic reticulum (ER) stress responses such as PERK and e1F-2α phosphorylation and CHOP expression. Moreover, TWS119 increased LPS-induced ER stress responses. On the basis of these results, the oncogenic protein ß-catenin is considered to be positively involved in LPS-induced cytotoxicity, possibly by downregulating ER stress responses.

Lipopolysaccharide prevents valproic acid-induced apoptosis via activation of nuclear factor-κB and inhibition of p53 activation.

The effect of lipopolysaccharide (LPS) on valproic acid (VPA)-induced cell death was examined by using mouse RAW 264.7 macrophage cells. LPS inhibited the activation of caspase 3 and poly (ADP-ribose) polymerase and prevented VPA-induced apoptosis. LPS inhibited VPA-induced p53 activation and pifithrin-α as a p53 inhibitor as well as LPS prevented VPA-induced apoptosis. LPS abolished the increase of Bax/Bcl-2 ratio, which is a critical indicator of p53-mediated mitochondrial damage, in response to VPA. The nuclear factor (NF)-κB inhibitors, Bay 11-7082 and parthenolide, abolished the preventive action of LPS on VPA-induced apoptosis. A series of toll-like receptor ligands, Pam3CSK4, poly I:C, and CpG DNA as well as LPS prevented VPA-induced apoptosis. Taken together, LPS was suggested to prevent VPA-induced apoptosis via activation of anti-apoptotic NF-κB and inhibition of pro-apoptotic p53 activation. The detailed inhibitory mechanism of VPA-induced apoptosis by LPS is discussed.

Pifithrin-α, a pharmacological inhibitor of p53, downregulates lipopolysaccharide-induced nitric oxide production via impairment of the MyD88-independent pathway.

The effect of pifithrin (PFT)-α, a pharmacological inhibitor of p53, on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophage-like cells was examined. PFT-α inhibited the production of NO but not tumor necrosis factor (TNF)-α in response to LPS. PFT-α inhibited LPS-induced NO production via reduced expression of an inducible NO synthase (iNOS). Moreover, PFT-α inhibited LPS-induced iNOS expression in p53-silenced cells. PFT-α inhibited the production of interferon (IFN)-ß, characteristic of the MyD88-independent pathway of LPS signaling, whereas it did not affect the activation of nuclear factor (NF)-κB and mitogen-activated protein kinases in the MyD88-dependent pathway. PFT-α inhibited poly I:C-induced NO production whereas it did not inhibit IFN-ß-induced NO production. Further, PFT-α reduced the expression of IFN regulatory factor 3 that leads to the IFN-ß production in the MyD88-independent pathway. The most upstream event impaired by PFT-α was the reduced expression of TNF receptor-associated factor (TRAF) 3 in the MyD88-independent pathway. PFT-α also reduced the in vivo expression of iNOS in the livers of mice injected with LPS. Taken together, PFT-α was suggested to inhibit LPS-induced NO production via impairment of the MyD88-independent pathway and attenuated LPS-mediated inflammatory response.

Inhibition of receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation by pyrroloquinoline quinine (PQQ).

The effect of pyrroloquinoline quinine (PQQ) on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation was examined using RAW 264.7 macrophage-like cells. RANKL led to the formation of osteoclasts identified as tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in the culture of RAW 264.7 cells. However, PQQ inhibited the appearance of osteoclasts and prevented the decrease of F4/80 macrophage maturation marker on RANKL-stimulated cells, suggesting a preventive action of PQQ on RANKL-induced osteoclast differentiation. PQQ inhibited the activation of nuclear factor of activated T cells (NFATc1), a key transcription factor of osteoclastogenesis, in RANKL-stimulated cells. On the other hand, PQQ did not inhibit the signaling pathway from RANK/RANKL binding to NFATc1 activation, including NF-κB and mitogen-activated protein kinases (MAPKs). PQQ augmented the expression of type I interferon receptor (IFNAR) and enhanced the IFN-ß-mediated janus kinase (JAK1) and signal transducer and activator of transcription (STAT1) expression. Moreover, PQQ reduced the expression level of c-Fos leading to the activation of NFATc1. Taken together, PQQ was suggested to prevent RANKL-induced osteoclast formation via the inactivation of NFATc1 by reduced c-Fos expression. The reduced c-Fos expression might be mediated by the enhanced IFN-ß signaling due to augmented IFNAR expression.

An ADP ribosylation factor-GTPase activating protein negatively regulates the production of proinflammatory mediators in response to lipopolysaccharide.

An ADP ribosylation factor-GTPase activating protein (ASAP1) is highly expressed in a variety of tumor cells and is involved in the cell motility, invasion, and metastasis. In order to elucidate the involvement of ASAP1 in lipopolysaccharide (LPS)-mediated inflammatory response, the effect of ASAP1 silencing on LPS-induced proinflammatory mediators production was examined by using RAW 264.7 macrophage-like cells. ASAP1 was constitutively expressed in the cells and the expression was augmented by LPS stimulation. Silencing of ASAP1 with small interfering RNA enhanced the production of tumor necrosis factor-α, interleukin 6, interferon-ß, and nitric oxide in response to LPS. ASAP1 silencing augmented the activation of nuclear factor (NF)-κB and several mitogen-activated protein kinases (MAPKs). On the other hand, ASAP1 silencing did not affect the expression of IRAK4, TRAF6, and Akt as the upstream molecules of NF-κB signaling. A series of toll-like receptor ligands as well as LPS augmented the ASAP1 expression. Taken together, ASAP1 was suggested to negatively regulate LPS-induced proinflammatory mediators production through down-regulating LPS signaling. The feedback function of ASAP1 in LPS-mediated inflammatory response is discussed.

Thalidomide inhibits interferon-γ-mediated nitric oxide production in mouse vascular endothelial cells.

Thalidomide is known as an anti-angiogenic, anti-tumor, and anti-proliferative agent, widely used in the treatment of some immunological disorders and cancers. The effect of thalidomide on interferon (IFN)-γ induced nitric oxide (NO) production in mouse vascular endothelial cells was examined in order to elucidate the anti-angiogenic or anti-inflammatory action. Thalidomide inhibited IFN-γ-induced NO production in mouse END-D cells via reduced expression of an inducible type of NO synthase (iNOS) protein and mRNA. Since thalidomide did not alter the cell surface expression of IFN-γ receptor, the NO inhibition was suggested to be due to the impairment of IFN-γ-induced intracellular event by thalidomide. Thalidomide inhibited the phosphorylation of IRF1, which was required for the iNOS expression. Moreover, it inhibited the phosphorylation of STAT1, an upstream molecule of IRF1, in IFN-γ signaling. Thalidomide did not inhibit the JAK activation in response to IFN-γ. A phosphatase inhibitor, sodium orthovanadate, abolished the inhibitory action of thalidomide. Therefore, thalidomide was suggested to inhibit IFN-γ-induced NO production via impaired STAT1 phosphorylation.

Flavopiridol inhibits lipopolysaccharide-induced TNF-α production through inactivation of nuclear factor-κB and mitogen-activated protein kinases in the MyD88-dependent pathway.

Flavopiridol is a cyclin-dependent kinase inhibitor and inhibits the growth of various cancer cells. The effect of flavopiridol on lipopolysaccharide (LPS)-induced proinflammatory mediator production was examined in RAW 264.7 macrophage-like cells. Flavopiridol significantly reduced the production of tumor necrosis factor-α and, to a lesser extent, nitric oxide in LPS-stimulated cells. Flavopiridol inhibited the activation of nuclear factor-κB and IκB kinase in response to LPS. Flavopiridol also inhibited the activation of a series of mitogen-activated protein kinases, such as p38, stress-activated protein kinase/c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2 in response to LPS. However, flavopiridol did not alter the expression of tumor necrosis factor receptor-associated factor 6, myeloid differentiation factor 88 (MyD88) or CD14/toll-like receptor (TLR) 4. Flavopiridol inhibited nitric oxide production induced by a MyD88-dependent TLR2 ligand, but not a MyD88-independent TLR3 ligand. Further, flavopiridol did not alter the phosphorylation of interferon regulatory factor 3 in the MyD88-independent pathway. Therefore, it was suggested that flavopiridol exclusively inhibited the activation of nuclear factor-κB and mitogen-activated protein kinases in the MyD88-dependent pathway. Flavopiridol might be useful for the prevention of LPS-induced inflammatory response.