High-mobility group box-1 protein induces mucin 8 expression through the activation of the JNK and PI3K/Akt signal pathways in human airway epithelial cells

Mechanism of endometrial MUC2 in reproductive performance in mice through PI3K/AKT signaling pathway after lipopolysaccharide treatment

The objective of this study was to investigate the effects of exposure to endotoxin on the reproductive performance of humans and animals in pregnancy and delivery period. Mucin is considered to play a critical role in protecting the tissue epithelium. At pregnancy period, the MUC2 expression of uterus in the High LPS group was significantly higher than that in the Control group. The glycosaminoglycans of gland cells were secreted into the uterine cavity to protect the uterus. Then, the MUC2 layer became thinner, and LPS entered the lamina propria of the uterus. The mRNA expression of tight junction proteins showed a marked drop, and morphological damage of the uterus occurred. Subsequently, the glycosaminoglycans of gland cells in the High LPS and Low LPS groups increased with the increasing LPS dose, and the damage to the endometrial epithelium was repaired in female mice at Day 5 postdelivery. A low dose of LPS activated the PI3K/AKT signaling pathways to increase the glycosaminoglycans particles, while a high dose of LPS inhibited the PI3K/AKT signaling pathway to decrease the glycosaminoglycans particles. Taken together, our results suggest that gland cells secreted glycosaminoglycans particles into the uterine cavity by exocytosis to increase the thickness of the mucus layer to protect the uterus and that this process was regulated by PI3K/AKT signaling pathways.

Tanshinone IIA derivatives induced S-phase arrest through stabilizing c-myc G-quadruplex DNA to regulate ROS-mediated PI3K/Akt/mTOR pathway

Herein, a derivate from tanshinone IIA, 1,6,6-trimethyl-11-phenyl-7,8,9,10-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazole (TA25), has been synthesized and investigated as potential inhibitor against the proliferation, migration and invasion of lung cancer cells. MTT assay and cell colony formation assay results showed that TA25 exhibits acceptable inhibitory effect against the proliferation of lung cancer A549 cells, and the value of IC₅₀ was about 17.9 μM. This result was further confirmed by the inhibition of TA25 against the growth of xenograft lung cancer cells on zebrafish bearing tumor (A549 lung cancer cells). The results of wound-healing assay and FITC-gelatin invasion assay displayed that TA25 could inhibit the migration and invasion of lung cancer A549 cells. Moreover, the studies on the binding properties of TA25 interact with c-myc G-quadruplex DNA suggested that TA25 can bind in the G-quarter plane formed from G7, G11, G16 and G20 with c-myc G-quadruplex DNA through π-π stacking. Further study of the potential anti-cancer mechanism indicated that TA25 can induce S-phase arrest in lung cancer A549 cells, and this phenomenon resulted from the promotion of the production of reactive oxygen species and DNA damage in A549 cells under the action of TA25. Further research revealed that TA25 could inhibit the PI3K/Akt/mTOR signal pathway and increase the expression of p53 protein. Overall, TA25 can be developed into a promising inhibitor against the proliferation, migration and invasion of lung cancer cells and has potential clinical application in the near future.

The Role of HMGB1, a Nuclear Damage-Associated Molecular Pattern Molecule, in the Pathogenesis of Lung Diseases

Significance: High-mobility group protein box 1 (HMGB1), a ubiquitous nuclear protein, regulates chromatin structure and modulates the expression of many genes involved in the pathogenesis of lung cancer and many other lung diseases, including those that regulate cell cycle control, cell death, and DNA replication and repair. Extracellular HMGB1, whether passively released or actively secreted, is a danger signal that elicits proinflammatory responses, impairs macrophage phagocytosis and efferocytosis, and alters vascular remodeling. This can result in excessive pulmonary inflammation and compromised host defense against lung infections, causing a deleterious feedback cycle. Recent Advances: HMGB1 has been identified as a biomarker and mediator of the pathogenesis of numerous lung disorders. In addition, post-translational modifications of HMGB1, including acetylation, phosphorylation, and oxidation, have been postulated to affect its localization and physiological and pathophysiological effects, such as the initiation and progression of lung diseases. Critical Issues: The molecular mechanisms underlying how HMGB1 drives the pathogenesis of different lung diseases and novel therapeutic approaches targeting HMGB1 remain to be elucidated. Future Directions: Additional research is needed to identify the roles and functions of modified HMGB1 produced by different post-translational modifications and their significance in the pathogenesis of lung diseases. Such studies will provide information for novel approaches targeting HMGB1 as a treatment for lung diseases.

High-Mobility Group Box 1 in Dry Eye Inflammation

Purpose

To determine high-mobility group box 1 (HMGB1) expression during experimental dry eye (EDE) and dry eye-like culture conditions and elucidate its role in corneal dry eye-related inflammation.

Methods

EDE was induced in 8- to 12-week-old C57BL/6 mice. Corneal tissue sections and lysates from EDE and untreated mice were evaluated for HMGB1 expression by immunostaining and quantitative real-time PCR (qPCR). For in vitro studies, human corneal epithelial cells (HCEC) were treated with hyperosmolar media, toll-like receptor (TLR) agonists, or proinflammatory cytokines to determine HMGB1 expression. HCEC were also treated with human recombinant HMGB1 (hrHMGB1) alone or in combination with inflammatory stimuli, and TNFα, IL-6, and IL-8 expression evaluated by qPCR and ELISA. Nuclear factor-κB (NF-κB) p65 nuclear translocation was determined by immunostaining.

Results

EDE mice had higher corneal HMGB1 RNA and protein expression compared to untreated animals. In HCEC, hyperosmolar stress and TNFα treatment stimulated HMGB1 production and secretion into culture supernatants. However, in vitro stimulation with hrHMGB1 did not induce secretion of TNFα, IL-6, or IL-8 or NF-κB p65 nuclear translocation. In addition, the inflammatory response elicited by TLR agonists fibroblast-stimulating lipopeptide-1 and lipopolysaccharide was not enhanced by hrHMGB1 treatment.

Conclusions

HMGB1 expression was enhanced by dry eye conditions in vivo as well as in vitro, during hyperosmolar stress and cytokine exposure, suggesting an important role for HMGB1 in dry eye disease. However, no direct inflammatory effect was observed with HMGB1 treatment. Therefore, under these conditions, HMGB1 does not contribute directly to dry eye-induced inflammation and its function at the ocular surface needs to be explored further.

Cyclic stretch induced IL-33 production through HMGB1/TLR-4 signaling pathway in murine respiratory epithelial cells

Interleukin 33 (IL-33), an inflammatory and mechanically responsive cytokine, is an important component of a TLR4-dependent innate immune process in mucosal epithelium. Although TLR4 also plays a role in sensing biomechanical stretch, a pathway of stretch-induced TLR4-dependent IL-33 biosynthesis has not been revealed. In the current study, we show that short term (6 h) cyclic stretch (CS) of cultured murine respiratory epithelial cells (MLE-12) increased intracellular IL-33 expression in a TLR4 dependent fashion. There was no detectable IL-33 in conditioned media in this interval. CS, however, increased release of the notable alarmin, HMGB1, and a neutralizing antibody (2G7) to HMGB1 completely abolished the CS mediated increase in IL-33. rHMGB1 increased IL-33 synthesis and this was partially abrogated by silencing TLR4 suggesting additional receptors for HMGB1 are involved in its regulation of IL-33. Collectively, these data reveal a HMGB1/TLR4/IL-33 pathway in the response of respiratory epithelium to mechanical stretch.

[Effect of heat shock factor 1 on airway hyperresponsiveness and airway inflammation in mice with allergic asthma]

OBJECTIVE

To investigate the effect of heat shock factor 1 (HSF1) on airway hyperresponsiveness and airway inflammation in mice with asthma and possible mechanisms.

METHODS

A total of 36 mice were randomly divided into four groups: control, asthma, HSF1 small interfering RNA negative control (siHSF1-NC), and siHSF1 intervention (n=9 each). Ovalbumin (OVA) sensitization and challenge were performed to induce asthma in the latter three groups. The mice in the siHSF1-NC and siHSF1 groups were treated with siHSF1-NC and siHSF1, respectively. A spirometer was used to measure airway responsiveness at 24 hours after the last challenge. The direct count method was used to calculate the number of eosinophils. ELISA was used to measure the serum level of OVA-specific IgE and levels of interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-13 (IL-13), and interferon-γ (IFN-γ) in lung tissues and bronchoalveolar lavage fluid (BALF). Quantitative real-time PCR was used to measure the mRNA expression of HSF1 in asthmatic mice. Western blot was used to measure the protein expression of HSF1, high-mobility group box 1 (HMGB1), and phosphorylated c-Jun N-terminal kinase (p-JNK).

RESULTS

The asthma group had significant increases in the mRNA and protein expression of HSF1 compared with the control group (P<0.05). The siHSF1 group had significantly reduced mRNA and protein expression of HSF1 compared with the siHSF1-NC group (P<0.05). The knockdown of HSF1 increased airway wall thickness, airway hyperresponsiveness, OVA-specific IgE content, and the number of eosinophils (P<0.05). Compared with the siHSF1-NC group, the siHSF1 group had significantly increased levels of IL-4, IL-5, and IL-13 and significantly reduced expression of IFN-γ in lung tissues and BALF (P<0.05), as well as significantly increased expression of HMGB1 and p-JNK (P<0.05).

CONCLUSIONS

Knockdown of HSF1 aggravates airway hyperresponsiveness and airway inflammation in asthmatic mice, and its possible mechanism may involve the negative regulation of HMGB1 and JNK.

HMGB1-TLR4 signaling contributes to the secretion of interleukin 6 and interleukin 8 by nasal epithelial cells

BACKGROUND

Alarmins play important roles in the pathogenesis of inflammatory and autoimmune diseases. However, the role of the alarmin protein high-mobility group box 1 (HMGB1) in upper airway inflammation is unclear.

OBJECTIVE

To determine if HMGB1 is present in the nasal mucosa and, if so, to elucidate its role in upper airway inflammation.

METHODS

Nasal secretions were collected from a total of 32 patients with chronic rhinosinusitis with nasal polyp, allergic rhinitis, and control subjects. The concentration of HMGB1 in nasal secretions and its tissue and cellular localization were examined by enzyme immunoassays and immunofluorescent staining of nasal polyps and cultured nasal epithelial cells. We then examined whether nasal epithelial cells secrete HMGB1 after inflammatory stimulation by tumor necrosis factor (TNF) α. The effects of HMGB1 on the production and secretion of interleukin (IL) 6 and IL-8 were also examined in cultured nasal epithelial cells.

RESULTS

Significantly higher concentrations of HMGB1 were found in nasal secretions from patients with chronic rhinosinusitis with nasal polyp or allergic rhinitis compared with the control subjects. HMGB1 expression was localized in the nuclei of epithelial cells and other constitutive cells in nasal polyps and in the nuclei of cultured nasal epithelial cells. TNF-α stimulated the production and secretion of HMGB1 by cultured nasal epithelial cells. HMGB1 stimulated the production and secretion of IL-6 and IL-8 by cultured nasal epithelial cells, and anti-toll-like receptor 4 blocking antibody significantly inhibited HMGB1-induced secretion of IL-6 and IL-8.

CONCLUSIONS

Nasal secretions contain substantial amounts of HMGB1. TNF-α stimulates the production of HMGB1, which, in turn, upregulates the production and secretion of IL-6 and IL-8 by nasal epithelial cells via toll-like receptor 4, which indicated that HMGB1 plays an important role in the pathogenesis of upper airway inflammation.

Cationic polyaspartamide-based nanocomplexes mediate siRNA entry and down-regulation of the pro-inflammatory mediator high mobility group box 1 in airway epithelial cells

High-mobility group box 1 (HMGB1) is a nonhistone protein secreted by airway epithelial cells in hyperinflammatory diseases such as asthma. In order to down-regulate HMGB1 expression in airway epithelial cells, siRNA directed against HMGB1 was delivered through nanocomplexes based on a cationic copolymer of poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) by using H441 cells. Two copolymers were used in these experiments bearing respectively spermine side chains (PHEA-Spm) and both spermine and PEG2000 chains (PHEA-PEG-Spm). PHEA-Spm and PHEA-PEG-Spm derivatives complexed dsDNA oligonucleotides with a w/w ratio of 1 and higher as shown by a gel retardation assay. PHEA-Spm and PHEA-PEG-Spm siRNA polyplexes were sized 350-650 nm and 100-400 nm respectively and ranged from negativity/neutrality (at 0.5 ratio) to positivity (at 5 ratio) as ζ potential. Polyplexes formed either at a ratio of 0.5 (partially complexing) or at the ratio of 5 (fully complexing) were tested in subsequent experiments. Epifluorescence revealed that nanocomplexes favored siRNA entry into H441 cells in comparison with naked siRNA. As determined by flow cytometry and a trypan blue assay, PHEA-Spm and PHEA-PEG-Spm allowed siRNA uptake in 42-47% and 30% of cells respectively, however only with PHEA-Spm at w/w ratio of 5 these percentages were significantly higher than those obtained with naked siRNA (20%). Naked siRNA or complexed scrambled siRNA did not exert any effect on HMGB1mRNA levels, whereas PHEA-Spm/siRNA at the w/w ratio of 5 down-regulated HMGB1 mRNA up to 58% of control levels (untransfected cells). PEGylated PHEA-Spm/siRNA nanocomplexes were able to down-regulate HMGB1 mRNA levels up to 61% of control cells. MTT assay revealed excellent biocompatibility of copolymer/siRNA polyplexes with cells. In conclusion, we have found optimal conditions for down-regulation of HMGB1 by siRNA delivery mediated by polyaminoacidic polymers in airway epithelial cells in the absence of cytotoxicity. Functional and in-vivo studies are warranted.

S100A8, S100A9 and S100A12 activate airway epithelial cells to produce MUC5AC via extracellular signal-regulated kinase and nuclear factor-κB pathways

Airway mucus hyperproduction is a common feature of chronic airway diseases such as severe asthma, chronic obstructive pulmonary disease and cystic fibrosis, which are closely associated with neutrophilic airway inflammation. S100A8, S100A9 and S100A12 are highly abundant proteins released by neutrophils and have been identified as important biomarkers in many inflammatory diseases. Herein, we report a new role for S100A8, S100A9 and S100A12 for producing MUC5AC, a major mucin protein in the respiratory tract. All three S100 proteins induced MUC5AC mRNA and the protein in normal human bronchial epithelial cells as well as NCI-H292 lung carcinoma cells in a dose-dependent manner. A Toll-like receptor 4 (TLR4) inhibitor almost completely abolished MUC5AC expression by all three S100 proteins, while neutralization of the receptor for advanced glycation end-products (RAGE) inhibited only S100A12-mediated production of MUC5AC. The S100 protein-mediated production of MUC5AC was inhibited by the pharmacological agents that block prominent signalling molecules for MUC5AC expression, such as mitogen-activated protein kinases, nuclear factor-κB (NF-κB) and epidermal growth factor receptor. S100A8, S100A9 and S100A12 equally elicited both phosphorylation of extracellular signal-regulated kinase (ERK) and nuclear translocation of NF-κB/degradation of cytosolic IκB with similar kinetics through TLR4. In contrast, S100A12 preferentially activated the ERK pathway rather than the NF-κB pathway through RAGE. Collectively, these data reveal the capacity of these three S100 proteins to induce MUC5AC production in airway epithelial cells, suggesting that they all serve as key mediators linking neutrophil-dominant airway inflammation to mucin hyperproduction.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Visfatin induces MUC8 and MUC5B expression via p38 MAPK/ROS/NF-κB in human airway epithelial cells

Background

Among a variety of inflammatory mediators, visfatin is a proinflammatory adipocytokine associated with inflammatory reactions in obesity, metabolic syndrome, chronic inflammatory disease, and autoimmune disease. However, the biological role of visfatin in secretion of major mucins in human airway epithelial cells has not been reported. Therefore, this study was conducted in order to investigate the effect and the brief signaling pathway of visfatin on MUC8 and MUC5B expression in human airway epithelial cells.

Results

Visfatin significantly induced MUC8 and MUC5B expression. Visfatin significantly activated phosphorylation of p38 MAPK. Treatment with SB203580 (p38 MAPK inhibitor) and knockdown of p38 MAPK by siRNA significantly blocked visfatin-induced MUC8 and MUC5B expression.Visfatin significantly increased ROS formation. Treatment with SB203580 significantly attenuated visfatin-induced ROS formation. Treatment with NAC (ROS scavenger) and DPI (NADPH oxidase inhibitor) significantly attenuated visfatin-induced MUC8 and MUC5B expression. However, treatment with NAC and DPI did not attenuate visfatin-activated phosphorylation of p38 MAPK. Visfatin significantly activated the phosphorylation of NF-κB. Treatment with PDTC (NF-κB inhibitor) significantly attenuated visfatin-induced MUC8 and MUC5B expression.

Conclusions

These results suggest that visfatin induces MUC8 and MUC5B expression through p38 MAPK/ROS/NF-κB signaling pathway in human airway epithelial cells.

Bornyl caffeate induces apoptosis in human breast cancer MCF-7 cells via the ROS- and JNK-mediated pathways

AIM

The purpose of the present study was to investigate the anticancer activity of bornyl caffeate in the human breast cancer cell line MCF-7.

METHODS

The cell viability was determined using the MTT assay, and apoptosis was initially defined by monitoring the morphology of the cell nuclei and staining an early apoptotic biomarker with Annexin V-FITC. The mitochondrial membrane potential was visualized by JC-1 under fluorescence microscopy, whereas intracellular reactive oxygen species (ROS) were assessed by flow cytometry. The expression of apoptosis-associated proteins was determined by Western blotting analysis.

RESULTS

Bornyl caffeate induced apoptosis in MCF-7 cells in a dose- and time-dependent manner. Consistently, bornyl caffeate increased Bax and decreased Bcl-xl, resulting in the disruption of MMP and subsequent activation of caspase-3. Moreover, bornyl caffeate triggered the formation of ROS and the activation of the mitogen-activated protein (MAP) kinases p38 and c-Jun N-terminal kinase (JNK). Antioxidants attenuated the activation of MAP kinase p38 but barely affected the activation of JNK. Importantly, the cytotoxicity of bornyl caffeate was partially attenuated by scavenging ROS and inhibited by MAP kinases and caspases.

CONCLUSION

The present study demonstrated that bornyl caffeate induced apoptosis in the cancer cell line MCF-7 via activating the ROS- and JNK-mediated pathways. Thus, bornyl caffeate may be a potential anticancer lead compound.

High mobility group box-1 promotes the proliferation and migration of hepatic stellate cells via TLR4-dependent signal pathways of PI3K/Akt and JNK

Background

The migration of hepatic stellate cells (HSCs) is essential to the hepatic fibrotic response, and recently High-mobility group box 1 (HMGB1) has been shown up-regulated during liver fibrosis. Nevertheless, whether HMGB1 can modulate the proliferation and migration of HSCs is poorly understood, as well as the involved intracellular signaling. In this study, we examined the effect of HMGB1 on proliferation, migration, pro-fibrotic function of HSCs and investigated whether toll-like family of receptor 4 (TLR4) dependent signal pathway is involved in the intracellular signaling regulation.

Methodology/Principal Findings

Modified transwell chamber system to mimic the space of Disse was used to evaluate the migration of human primary HSCs, and the protein expressions of related signal factors were evaluated by western blot. Cell proliferation was analyzed by MTT assay, the pro-fibrotic functions of HSCs by qRT-PCR and ELISA respectively. Recombinant human HMGB1 could significantly promote migration of HSCs under both haptotactic and chemotactic stimulation, especially the latter. Human TLR4 neutralizing antibody could markedly inhibit HMGB1-induced migration of HSCs. HMGB1 could enhance the phosphorylation of JNK and PI3K/Akt, and TLR4 neutralizing antibody inhibited HMGB1-enhanced phosphorylation of JNK and PI3K/Akt and activation of NF-κB. JNK inhibitor (SP600125) and PI3K inhibitor (LY 294002) significantly inhibited HMGB1-induced proliferation and migration of HSCs, and also reduced HMGB1-enhanced related collagen expressions and pro-fibrotic cytokines production.

Conclusions/Significance

HMGB1 could significantly enhance migration of HSCs in vitro, and TLR4-dependent JNK and PI3K/Akt signal pathways are involved in the HMGB1-induced proliferation, migration and pro-fibrotic effects of HSCs, which indicates HMGB1 might be an effective target to treat liver fibrosis.

Cellular and molecular biology of airway mucins

Airway mucus constitutes a thin layer of airway surface liquid with component macromolecules that covers the luminal surface of the respiratory tract. The major function of mucus is to protect the lungs through mucociliary clearance of inhaled foreign particles and noxious chemicals. Mucus is comprised of water, ions, mucin glycoproteins, and a variety of other macromolecules, some of which possess anti-microbial, anti-protease, and anti-oxidant activities. Mucins comprise the major protein component of mucus and exist as secreted and cell-associated glycoproteins. Secreted, gel-forming mucins are mainly responsible for the viscoelastic property of mucus, which is crucial for effective mucociliary clearance. Cell-associated mucins shield the epithelial surface from pathogens through their extracellular domains and regulate intracellular signaling through their cytoplasmic regions. However, neither the exact structures of mucin glycoproteins, nor the manner through which their expression is regulated, are completely understood. This chapter reviews what is currently known about the cellular and molecular properties of airway mucins.