Effects of zanthoxylum seed oilA2 on NF-кB signaling pathway and inflammatory factor in lung tissue of asthmatic mice

AIM: To investigate the dynamic influence of zanthoxylum seed oilA2 (ZSOA2) on NF-кB signaling pathway and inflammatory factor in pulmonary tissue of asthmatic mice. METHODS: The suspensoid (0.2 mL containing 20% albumin hydroxide and 10% ovalbumin) was administered by intraperitoneal injection to sensitize the BALB/c mice on day 1, then 0.4% ovalbumin solution (50 μL in phosphate buffer fluid) was dripped into the respiratory tract through nasal cavity to establish the asthmatic mouse model. After dripped ovalbumin for 24 h, 48 h, 3 d, 7 d and 14 d, the mice were killed at specified time points. The contents of interleukin-4 (IL-4), interleukin-5 (IL-5) and interferon-γ (IFN-γ) in bronchoalveolar lavage fluid (BALF) were determined by ELISA. The pathological changes of the lung tissues were observed with HE staining. The inflammatory cell counts were conducted by Eosin staining. The protein levels of adhesion molecule and the molecules of NF-κB signaling pathway in lung tissues were determined by Western blotting. RESULTS: In ZSOA2 treated mice, the pathological injury of the lung was significantly attenuated as compared to the model mice, the counts of eosinophils and lymphocytes were reduced obviously in lung bronchial area of asthmatic mice at all observed time points (P<0.05). The levels of IL-5 and IL-4 decreased and IFN-γ increased in BALF. The results of Western blotting showed that ZSOA2 down-regulated the protein levels of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, I kappa B kinase alpha-α and phosphorylation inhibitory-κB. ZSOA2 also up-regulated the protein levels of tumor necrosis factor receptor 1 and phosphorylation nuclear factor-kappaB in lung tissue at all observed time points. CONCLUSION: ZSOA2 has therapeutic effect on asthma by down-regulating the protein expression of IκB-β and p-IκB, inhibiting the releases of cytokines and chemotactic factors, and attenuating the infiltration of inflammatory cells in the lungs of ovalbumin challenged asthma mice.     

Phosphoglycerate mutase 5 and necroptosis

Necroptosis, or programmed cell death, is a type of cell death with a controllable death signaling pathway and the morphological features similar to necrosis. It is mainly mediated by death receptors or pathogen pattern re-cognition receptors. Among them, tumor necrosis factor receptor 1 (TNFR1)-mediated necroptosis is the most well-studied one. Receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3) are the 2 key kinases involved in the formation of complex I & II and necrosome in the process of necroptosis. Phosphoglycerate mutase 5 (PGAM5), a member of phosphoglycerate mutase gene family, lacks PGAM activity and possesses the phosphatase activity. PGAM5 is anchored in the mitochondrial membrane and is also called mitochondrial phosphoglycerate mutase 5. It has been shown that PGAM5 involves in the formation of necrosome during necroptosis and it is able to accelerate the fission of mitochondria by dephosphorylation of dynamin-related protein 1 (DRP1), thus promoting cell necroptosis.     

Effect of Shaofu-Zhuyu decoction on MAPK/ERK signaling pathway in rats with endometriosis

AIM: To observe the effects of Shaofu-Zhuyu decoction (SFZY) on mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway in the rats with endometriosis (EM), and to explore the mechanism of SFZY for treatment of EM.METHODS: Healthy female SD rats were used to establish the EM model. The rats were randomly divided into blank control group, model group, positive control group, and low dose, middle dose and high dose of SFZY groups. The pathological changes of the endometriotic tissue were observed by HE staining. The levels of tumor necrosis factor-α (TNF-α), interleukin-6(IL-6) and IL-8 in the uterine tissue were detected by ELISA. The mRNA expression of ERK, vascular endothelial growh factor (VEGF) and matrix metalloprotein-9 (MMP-9) was detected by RT-qPCR. The protein expression of nuclear factor-κB (NF-κB), MAPK and MAPK-ERK kinase (MEK) was determined by Western blot.RESULTS: Compared with model group, the levels of TNF-α, IL-6 and IL-8 in the uterine tissue of the rats in middle dose and high dose of SFZY groups were significantly decreased (P<0.05), the mRNA expression of ERK, VEGF and MMP-9 was significantly reduced, and the protein expression of NF-κB, MEK and MAPK was decreased significantly in the rat endometriotic tissues (P<0.05).CONCLUSION: SFZY may play a key role in the treatment of EM by regulating MAPK/ERK signaling pathway.     

Disease mechanisms and emergence therapies: protein kinases and their inhibitors in cardiovascular diseases

Cardiovascular diseases (CVDs) are a major cause of morbidity and mortality in the world. So far, there has been substantial progress toward understanding the pathophysiology and treatment of CVDs. There are multiple cell signaling cascades, some of which are beneficial or compensatory and others deleterious. The balance between these pathways determines the outcome as a diseased or non-diseased state. Protein phosphorylation, which is mediated by enzymes, called protein kinases, is a major mechanism for transducing external stimuli into intracellular signals. Electively targeting of signaling pathways using protein kinase inhibitors would have a potential advantage over receptor blockers. By now, there are types of protein kinase inhibitiors available for treating several diseases. The success of kinase inhibitors in cancer treatment has strongly supported application in the treatment of CVDs. Here, we will review several kinds of protein kinases as potential targets for CVDs and some difficulty in identifying a protein kinase as a putative therapeutic target for CVDs.     

Effect of fractalkine on neuroprotection

The chemokine fractalkine primarily involves in chemotaxis,adherence and inflammation.Recently it has been discovered owning the ability of inhibiting cell death in neurons and glial cells,as well as protecting central nervous system from toxic damage.Fractalkine reduces the toxicity to neurons and glial cells mediated by excessive Fas L,glutamate (Glu) or lipopolysaccharide (LPS).In vivo neutralization of endogenous brain fractalkine signal pathway increases inflammatory cytokines secretion and neuronal cell death induced by LPS.Fractalkine may achieve its neuroprotective property through influencing expression of pro-apoptotic and anti-apoptotic proteins,intracellular Ca2+ level and inflammatory cytokines secretion via protein kinase B (PKB)/Akt and extracellular signal-regulated kinase (ERK)/MAPK pathways.     

Progress in protein kinase B

Protein kinase B (Akt) is a Ser/Thr kinase, which in mammals comprise three highly homologous members known as PKBα/Akt1, PKBβ/Akt2 and PKBγ/Akt3. PKB is activated by hormones?growth factor and extra cellular matrix. The activation occurs downstream of PI3K. PKB phosphorylates and regulates the function of many cellular protein involved in processes that include survival, apoptosis, proliferation, glycogen metabolism and cancer progression. Although many mechanisms remains to be fully characterized, the research of PKB is thought to have a useful profect.     

Effect of FSD-C10 on modulation of inflammatory microenvironment in an Alzheimer disease double transgenic mouse model

AIM: To explore the therapeutic effect of a novel Rho kinase inhibitor FSD-C10 on β-amyloid protein precursor (APP)/presenilin-1 (PS1) double transgenic mice. METHODS: The transgenic mice overexpressing human APP with the Swedish mutation (695) and human PS1 with ΔE9 mutation at the age of 8 months were used in this study. The mice were randomly divided into model group and FSD-C10 intervention group, and wild-type mice at the same age served as normal controls. The mice in FSD-C10 intervention group were treated with FSD-C10 (25 mg·kg^-1·d^-1) for 2 months by intraperitoneal injection. The mice in model group and the wild-type mice were injected with saline in the similar manner. Morris water maze (MWM) test was applied to examine the capacity of learning and memory. The Aβ_1-42 deposition, Tau protein phosphorylation, and the expression of β-site APP-cleaving enzyme (BACE) as well as inflammatory molecules, such as TLR-4 and NF-κB, and M1/M2 microglial markers, such as iNOS and Arg-1, were determined by the methods of immunohistochemistry and Western blot. RESULTS: Compared with model group, FSD-C10 significantly improved the learning and memory abilities of APP/PS1 double transgenic mice, accompanied by reduced Aβ_1-42 deposition, Tau protein phosphorylation and BACE expression in the hippocampus. The intervention of FSD-C10 decreased the protein levels of TLR-4 and p-NF-κB, reduced the expression of iNOS and increased the expression of Arg-1 in the brain tissues. CONCLUSION: The novel Rho kinase inhibitor FSD-C10 improves the capacity of spatial learning and memory in APP/PS1 double transgenic mice, which may be related to the inhibition of TLRs/NF-κB signaling pathway, the reduction of the secretion of inflammatory molecules and the polarization of anti-inflammatory M2 microglia, thus improving the inflammatory microenvironment of the brain in APP/PS1 double transgenic mice.     

1,25-dihydroxyvitamin D3 inhibits nuclear factor kappa B signaling pathway in passively sensitized human airway smooth muscle cells

AIM:To investigate the effects of 1,25-dihydroxyvitamin D3 ［1,25-(OH)2D3］ on nuclear factor kappa B (NF-κB) signaling pathway in passively sensitized human airway smooth muscle cells (HASMCs). METHODS:HASMCs were passively sensitized with 10% serum from asthmatic patients. 1,25-(OH)2D3 was used as an interfering factor. Electrophoretic mobility shift assay (EMSA) was used to detect the DNA-binding activity of NF-κB. Immunocytochemical staining was used to observe the nuclear translocation of NF-κB p65. Western blotting was used for IκBα and phosphorylated IκBα protein detection. Real-time fluorescence quantitative PCR was used to determine vitamin D receptor (VDR), vitamin D 24-hydroxylase (CYP24) and IκBα mRNA expression. The mRNA expression of IκBα in HASMCs after actinomycin D treatment was also determined. RESULTS:(1) 1,25-(OH)2D3 significantly attenuated the DNA-binding activity of NF-κB and the nuclear translocation of NF-κB p65 in HASMCs passively sensitized by asthmatic serum. (2) 1,25-(OH)2D3 enhanced IκBα mRNA stability and inhibited IκBα protein phosphorylation in passively sensitized HASMCs, thus increasing IκBα expression in these HASMCs. (3) 1,25-(OH)2D3 up-regulated VDR mRNA level and evoked its functional response in passively sensitized HASMCs. CONCLUSION: 1,25-(OH)2D3 enhanced the expression of IκBα and therefore inhibited NF-κB signaling passway in HASMCs. This effect may be dependent on VDR, and responsible for the inhibitory effect of 1,25-(OH)2D3 on passively sensitized HASMCs.     

LRRK2/NF-κB signaling modulates inflammatory responses in BCG-infected RAW264.7 macrophages

AIM: To investigate the biological function and potential mechanism of leucine-rich repeat kinase 2 (LRRK2) in RAW264.7 macrophages during Mycobacterium tuberculosis infection. METHODS: The bacillus Calmette-Guerin (BCG)-infected RAW264.7 cell model was established. Colony-forming unit (CFU) analysis was used to determine the mycobacterial viability. The releases of interleukin (IL)-1β, IL-6 and interferon-γ (IFN-γ) in the RAW264.7 cells were detected by ELISA. qPCR and Western blot were used to measure the mRNA and protein expression levels, respectively. RESULTS: LRRK2 was robustly enhanced in the RAW264.7 cells in response to BCG infection. Additionally, silencing of LRRK2 suppressed intracellular growth of mycobacteria during BCG challenge. Moreover, silencing of LRRK2 dramatically attenuated the accumulation of inflammatory cytokines IL-1β, IL-6 and IFN-γ induced by BCG infection. More importantly, LRRK2 modulated BCG-induced inflammatory responses by positively regulating the nuclear factor-κB (NF-κB) signaling pathway. CONCLUSION: LRRK2/NF-κB signaling pathway positively modulates inflammatory responses during BCG infection, which may provide a better understanding of the pathogenesis of tuberculosis and useful information for developing potential therapeutic interventions against the disease.     

Effects of bradykinin on proliferation of porcine pulmonary artery smooth muscle cells induced by TGF-β1

AIM: To investigate the effects of bradykinin (BK) on the proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by transforming growth factor beta 1 (TGF-β1) and its possible mechanisms. METHODS: Primary porcine PASMCs were isolated, cultured and identified, and the cells at passages 2~6 were used in this study. The viability of PASMCs was determined by Cell Counting Kit-8 assay. The protein expression of phosphatidylinositol 3-kinase (PI3K), phosphorylated Akt (p-Akt) and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) was detected by Western blotting. RESULTS: TGF-β1 promoted the proliferation of PASMCs in a dose-dependent manner (P<005). BK significantly inhibited the proliferation of PASMCs induced by TGF-β1 (P<005), and attenuated the elevated expression of PI3K, p-Akt and p-ERK1/2 proteins (P<005). HOE-140, a BK type 2 receptor (B2R) inhibitor, reversed the effects of BK (P<005). CONCLUSION: BK inhibits TGF-β1-induced proliferation of PASMCs, which may be associated with inactivation of PI3K/Akt and ERK1/2 signaling pathways.     

Resveratrol attenuates inflammatory pain induced by complete Freund's adjuvant via NF-κB signaling pathway in a mouse model

AIM: To investigate the anti-inflammatory action of resveratrol (Res) and its correlation with nuclear factor-κB (NF-κB) signaling pathway in a mouse model of inflammatory pain.METHODS: BALB/c mice (n=60) were randomly divided into 6 groups:normal control group, inflammatory pain model group, positive control (dexamethasone, 0.5 mg/kg) group and resveratrol (100, 50 and 25 mg/kg) groups (10 mice in each group). In order to observe the anti-inflammatory pain effects of reseratrol on mice, the paw withdrawal mechanical threshold, paw withdrawal thermal latency and cold withdrawal times were detected. In order to analyze the mechanism of analgesic effect of resveratrol, the expression levels of NF-κB, inhibitor of NF-κB (IκB) α, inhibitor of NF-κB kinase (IKK) β, tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the spinal cord tissues (L4~L6) of the mice were determined by RT-PCR and Western blot.RESULTS: The resveratrol at 100 and 50 mg/kg increased the paw withdrawal mechanical threshold, prolonged the paw withdrawal thermal latency, and decreased the cold withdrawal times in the inflammatory pain mice (P<0.05 or P<0.01). The resveratrol at 100 mg/kg down-regulated the mRNA and protein expression levels of NF-κB, IκBα, IKKβ, TNF-α and IL-1β in the spinal cord tissues (L4~L6) of inflammatory pain mice (P<0.05 or P<0.01).CONCLUSION: Resveratrol ameliorates the inflammatory pain of the mice induced by complete Freund's adjuvant. The mechanism is related to the inhibition of NF-κB signaling pathway.     

Effects of BCL6B on proliferation and migration of human colorectal carcinoma LoVo cells and its potential mechanism

AIM: To detect the endogenous expression of B-cell leukemia/lymphoma 6 member B (BCL6B) in FHC and LoVo cells, and to investigate the effects of BCL6B on proliferation and migration of LoVo cells for further exploring the underlying mechanism. METHODS: The endogenous expression of BCL6B in the FHC and LoVo cells was detected by RT-PCR and Western blot. The methods of MTT assay, colony formation assay, wound healing assay and Transwell chamber experiment were employed to examine the biological functions of BCL6B in the LoVo cells. The mRNA and protein levels of BCL6B, cyclin D1 and matrix metalloproteinase-9 (MMP-9) were determined by RT-PCR and Western blot, respectively. The level of phosphorylated protein kinase B (p-AKT) was detected by Western blot. RESULTS: BCL6B expression was notably repressed in the LoVo cells as compared with the FHC cells, which were significantly increased by transfection with pcDNA3.1-BCL6B. The abilities of proliferation and migration of the LoVo cells at 72 h were inhibited by 28.33%(P<0.01) and 36.11%(P<0.05) in BCL6B group. The mRNA levels of cyclin D1 and MMP-9 in the cells of BCL6B group were decreased by 39.90%(P<0.01) and 77.36% (P<0.05), and the protein levels of cyclin D1, MMP-9 and p-AKT were reduced by 44.00%(P<0.05), 47.06%(P<0.01) and 32.88% (P<0.05), respectively. CONCLUSION: BCL6B inhibits proliferation and migration of the LoVo cells, and the PI3K/AKT signaling pathway is involved in this process.     

Regulatory effects of reactive oxygen species on the production of PAI-1 in 3T3-L1 adipocytes and its related possible mechanisms

AIM: To investigate the regulatory effects of reactive oxygen species (ROS) on the production of plasminogen activator inhibitor 1 (PAI-1), and try to determine the signaling cascades involved in it. METHODS: 3T3-L1 cells were cultured and differentiated into mature adipocytes. Cell viability was measured by MTT. The PAI-1 mRNA expression levels were evaluated by quantitative real-time PCR. Quantification of the PAI-1 protein levels secreted into conditioned medium was performed by multiplex immunoassay and sandwich ELISA. The phosphorylation status of protein kinases was determined by Bio-Plex phosphoprotein assays. RESULTS: In 3T3-L1 adipocytes, H2O2 significantly augmented the expression of PAI-1. Also, H2O2 activated several signaling pathways including ERK1/2, JNK, Akt, p70 S6K and JAK/STAT. Verified by protein kinase inhibitors, Akt, JAK/STAT and ERK1/2 may participate in the H2O2-induced increase in PAI-1. CONCLUSION: H2O2 markedly up-regulates the production of PAI-1 in 3T3-L1 adipocytes via some intracellular signaling pathways such as Akt, JAK/STAT and ERK1/2.     

Berberine inhibits enterocyte apoptosis in septic mice

AIM: To observe the effects of berberine (Ber) on enterocyte apoptosis in septic mice and its possible mechanism. METHODS: Male C57BL/6 mice (8~10 weeks old) were randomly divided into sham group, cecal ligation and puncture (CLP) group, CLP+Ber group and sham+Ber group. The mice in CLP group underwent CLP ope-ration, and the mice in sham groups suffered a similar operation except the ligation and puncture. After the sham or CLP operation, the mice were administered intragastrically with distilled water or berberine (50 mg/kg) within 2 h. After 20 h, the mice were killed with excess pentobarbital sodium and the ileum tissues were removed. The histological changes of the intestine were observed and the enterocyte apoptosis was examined by determining the protein level of cleaved caspase-3. Furthermore, mitochondrial Bax, cytoplasm cytochrome C (Cyt C) and the total proteins of Bcl-2, Fas, FasL and Fas-associated protein with death domain (FADD) were examined by Western blot. The mRNA expression of tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was measured by real-time PCR. RESULTS: The extensive ileum injuries, including remarkably increased leukocytes and necrosis of intestinal villus were observed 20 h after CLP. In CLP group, the protein levels of cleaved caspase-3, cytoplasm Cyt C, as well as Fas, FasL were significantly increased, but the Bcl-2 level was decreased. Bax translocation into mitochondria was promoted. However, FADD was not changed significantly. The mRNA expression of TH and DBH was also increased sharply in CLP group. On the contrary, treatment with berberine made a considerable alleviating alteration in the ileum of the septic mice.CONCLUSION: Treatment with berberine provides protective effects on intestinal injury in septic mice by reducing enterocyte apoptosis, and its possible mechanism may be involved in the inhibition of the endogenous and exogenous apoptosis pathways.     

Inhibitory effect of butylphthalide on apoptosis of hippocampal neurons in Alzheimer disease rats via SIRT1/NF-κB signaling pathway

AIM: To investigate the effect of butylphthalide on apoptosis of hippocampal neurons in Alzheimer disease (AD) rats via SIRT1/NF-κB signaling pathway and its mechanism. METHODS: AD rat model was established by intragastric administration of AlCl₃ and intraperitoneal injection of D-galactose. After treated with butylphthalide at 25 mg/kg (low dose), 50 mg/kg (medium dose) and 100 mg/kg (high dose), the effects of butylphthalide on the morphology of hippocampal neurons, apoptosis rate, and the protein levels of Bcl-2, Bax, cleaved caspase-3 and the SIRT1/NF-κB signaling pathway associated proteins were determined by HE staining, flow cytometry and Western blot, respectively. After treated with SIRT1 agonist SRT1720 and inhibitor sirtinol, the role of SIRT1/NF-κB signaling pathway in hippocampal neuronal apoptosis was observed. On the basis of giving 50 mg/kg butylphthalide, sirtinol was administered, and the effect of butylphthalide on neuronal apoptosis regulated by SIRT1/NF-κB signaling pathway was evaluated. RESULTS: The morphology of hippocampal neurons in the AD rats were improved, the apoptosis rate of hippocampal neurons and the protein levels of Bax and cleaved caspase-3 were inhibited, and the protein levels of Bcl-2 and the activation of SIRT1/NF-κB signaling pathway were promoted by butylphthalide significantly (P<0.05). The protein expression of Bcl-2 and the activation of SIRT1/NF-κB signaling pathway were promoted, and the apoptosis of hippocampal neurons and the protein levels of Bax and cleaved caspase-3 were inhibited by SRT1720 remarkably (P<0.05), whereas the effect of sirtinol was contrary to that of SRT1720. After sirtinol treatment, the inhibitory effect of butylphthalide on apoptosis of hippocampal neurons, the protein levels of Bax and cleaved caspase-3, and the promotion of Bcl-2 protein expression in hippocampal neurons were markedly weakened (P<0.05). CONCLUSION: Butylphthalide inhibits the apoptosis of hippocampal neurons in the AD rats by down-regulating the protein expression of Bax and cleaved caspase-3, and up-regulating the protein expression of Bcl-2 through activating SIRT1/NF-κB signaling pathway.     

Effects of dexmedetomidine on behaviors and expression of BDNF and mTOR in hippocampus of depressive rats

AIM: To investigate the effects of dexmedetomidine (DEX) on the behaviors and the expression of brain-derived neurotrophic factor (BDNF) and mammalian target of rapamycin (mTOR) in the hippocampus of depressive rats. METHODS: Sprague-Dawley (SD) rats were randomly divided into 5 groups: sham operation group, model group, and DEX (2.5, 5 and 10 μg/kg) groups. The rats were randomly selected in each group (n=12). The rat depression model was established by chronic unpredictable mild stress and ovariectomy. The rats in DEX groups received daily DEX treatment via intraperitoneal injection for 21 d. The forced swimming immobility time (FSIT) and open-field test were used to evaluate the antidepressant effect of DEX. Escape latency and times of crossing the flat were evaluated by Morris water maze. The histological changes of hippocampal neurons were determined by Nissl staining. The mRNA levels of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were detected by RT-qPCR. The protein expression of IL-1β, IL-6, TNF-α and BDNF, and the phosphorylation levels of protein kinase A (PKA), cAMP response element-binding protein (CREB), tropomyosin-related kinase B (TrkB), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt) and mTOR in hippocampus were evaluated by Western blot. RESULTS: Compared with model group, the FSIT was significantly reduced and the spontaneous activity was markedly increased in DEX groups. The damage of the hippocampal neurons was obviously attenuated, the escape latency was obviously decreased, and times of crossing the flat were markedly increased (P<0.05 or P<0.01). The levels of IL-1β, IL-6 and TNF-α were obviously decreased, and the protein levels of p-PKA, p-CREB, BDNF, p-TrkB and p-PI3K, p-Akt, p-mTOR in hippocampal tissues were obviously increased (P<0.05 or P<0.01). CONCLUSION: Dexmedetomidine improves the behaviors and the spatial learning and memory ability of depressive model rats, which may be related to its anti-inflammatory effects, as well as up-regulating the protein levels of BDNF and p-TrkB, and activating PI3K/Akt/mTOR signaling pathway in the hippocampus.     

Establishment of human lung infection model in vitro and mechanisms of NTHi-induced inflammatory responses

AIM: To investigate the key signal pathways of inflammatory responses in lung tissues induced by the infection of nontypeable Haemophilus influenzae(NTHi). METHODS: Human lung tissues were co-incubated with NTHi (10¹⁰ CFU/L) for 4 h and 24 h, respectively. The phosphorylation of p38 mitogen-activated protein kinase (MAPK) was detected by Western blotting. The nuclear translocation of nuclear factor (NF)-κB was examined by electrophoretic mobility shift assay (EMSA). The expression of Toll-like receptor (TLR) 2 was measured by real-time quantitative RT-PCR, and the level of interleukin (IL)-8 was detected by enzyme-linked immunosorbent assay (ELISA). Furthermore, lung tissues were incubated with anti-TLR2 monoclonal antibody (5 mg/L), p38 MAPK inhibitor SB203580 (20 μmol/L), or NF-κB inhibitor PDTC (25 μmol/L) for 2 h, then stimulated with NTHi (10¹⁰ CFU/L) for another 24 h. The supernatants were collected for IL-8 detection. RESULTS: The TLR2-p38 MAPK-NF-κB signaling pathway in lung tissues was rapidly activated 4 h after NTHi stimulation. IL-8 secreted from lung tissues infected with NTHi was significantly increased compared with uninfected lungs (P<0.05). The pre-incubation with anti-TLR2 antibody, p38 MAPK inhibitor or NF-κB inhibitor markedly decreased IL-8 production induced by NTHi. CONCLUSION: NTHi induces inflammatory responses in lung tissues by activation of TLR2-p38 MAPK-NF-κB signaling pathway. Human lung infection model provides a new research tool for the study of interaction between pathogens and hosts.