Downregulation by a long-acting beta2-adrenergic receptor agonist and corticosteroid of Staphylococcus aureus-induced airway epithelial inflammatory mediator production

Inhaled β2 Adrenergic Agonists and Other cAMP-Elevating Agents: Therapeutics for Alveolar Injury and Acute Respiratory Disease Syndrome?

Inhaled long-acting β-adrenergic agonists (LABAs) and short-acting β-adrenergic agonists are approved for the treatment of obstructive lung disease via actions mediated by β2 adrenergic receptors (β2-ARs) that increase cellular cAMP synthesis. This review discusses the potential of β2-AR agonists, in particular LABAs, for the treatment of acute respiratory distress syndrome (ARDS). We emphasize ARDS induced by pneumonia and focus on the pathobiology of ARDS and actions of LABAs and cAMP on pulmonary and immune cell types. β2-AR agonists/cAMP have beneficial actions that include protection of epithelial and endothelial cells from injury, restoration of alveolar fluid clearance, and reduction of fibrotic remodeling. β2-AR agonists/cAMP also exert anti-inflammatory effects on the immune system by actions on several types of immune cells. Early administration is likely critical for optimizing efficacy of LABAs or other cAMP-elevating agents, such as agonists of other Gs-coupled G protein-coupled receptors or cyclic nucleotide phosphodiesterase inhibitors. Clinical studies that target lung injury early, prior to development of ARDS, are thus needed to further assess the use of inhaled LABAs, perhaps combined with inhaled corticosteroids and/or long-acting muscarinic cholinergic antagonists. Such agents may provide a multipronged, repurposing, and efficacious therapeutic approach while minimizing systemic toxicity. SIGNIFICANCE STATEMENT: Acute respiratory distress syndrome (ARDS) after pulmonary alveolar injury (e.g., certain viral infections) is associated with ∼40% mortality and in need of new therapeutic approaches. This review summarizes the pathobiology of ARDS, focusing on contributions of pulmonary and immune cell types and potentially beneficial actions of β2 adrenergic receptors and cAMP. Early administration of inhaled β2 adrenergic agonists and perhaps other cAMP-elevating agents after alveolar injury may be a prophylactic approach to prevent development of ARDS.

Effect of adenovirus mediated β2-AR overexpression on IL-10 level secreted by cardiomyocytes of heart failure rats

The effect of β₂-adrenergic receptor (AR) overexpression on interleukin (IL)-10 content secreted by cardiomyocytes of heart failure (HF) rats was investigated. A rat model of chronic HF was established by partially banding abdominal aorta and the cardiomyocytes were isolated with collagenase II. The cardiomyocytes were then transfected with adenovirus type 5-ADRβ₂-enhanced green fluorescent protein (EGFP) for 48 h to observe the changes of β₂-AR protein expression using western blot analysis. The IL-10 level was detected by ELISA. The experiment was divided into seven groups: Control, HF, HF+EGFP, HF+β₂, sham, sham+EGFP and sham+β₂ groups. Compared with the sham-operated group, left ventricular diastolic dimension, and left ventricular systolic dimension were increased (P<0.05), whereas ejection fraction and fractional shortening were decreased (P<0.05) in the HF group. Compared with the sham group, the cardiomyocyte survival rate of the HF group was significantly reduced (P<0.05). Compared with the control or sham group, the β₂-AR protein level of the HF group showed no significant differences (P>0.05). Compared with the HF and HF+EGFP groups, the expression of β₂-AR protein of cardiomyocytes was increased in the HF+β₂ group (P<0.05). Compared with the sham group, IL-10 content secreted by cardiomyocytes in the HF group was increased (P<0.05). Compared with the HF and HF+EGFP groups, IL-10 content in the HF+β₂ group was increased significantly (P<0.05). In conclusion, the concentration of IL-10 secreted by cardiomyocytes of HF rats was increased. The overexpression of β₂-AR in the cardiomyocytes of HF rats was able to enhance the secretion of IL-10.

Modulation of Human Airway Barrier Functions during Burkholderia thailandensis and Francisella tularensis Infection Running Title: Airway Barrier Functions during Bacterial Infections

The bronchial epithelium provides protection against pathogens from the inhaled environment through the formation of a highly-regulated barrier. In order to understand the pulmonary diseases melioidosis and tularemia caused by Burkholderia thailandensis and Fransicella tularensis, respectively, the barrier function of the human bronchial epithelium were analysed. Polarised 16HBE14o- or differentiated primary human bronchial epithelial cells (BECs) were exposed to increasing multiplicities of infection (MOI) of B. thailandensis or F. tularensis Live Vaccine Strain and barrier responses monitored over 24-72 h. Challenge of polarized BECs with either bacterial species caused an MOI- and time-dependent increase in ionic permeability, disruption of tight junctions, and bacterial passage from the apical to the basolateral compartment. B. thailandensis was found to be more invasive than F. tularensis. Both bacterial species induced an MOI-dependent increase in TNF-α release. An increase in ionic permeability and TNF-α release was induced by B. thailandensis in differentiated BECs. Pretreatment of polarised BECs with the corticosteroid fluticasone propionate reduced bacterial-dependent increases in ionic permeability, bacterial passage, and TNF-α release. TNF blocking antibody Enbrel(®) reduced bacterial passage only. BEC barrier properties are disrupted during respiratory bacterial infections and targeting with corticosteroids or anti-TNF compounds may represent a therapeutic option.

Nuclear factor erythroid 2-related factor 2 is a critical target for the treatment of glucocorticoid-resistant lupus nephritis

Background

Dimethyl fumarate (DMF), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, has been proven effective for the systemic treatment of multiple sclerosis. The aim of this study is to evaluate the anti-inflammatory effects of Nrf2 activators on human renal mesangial cells (HRMCs) and the development of lupus nephritis (LN) in mice.

Methods

To assess Nrf2 activation in vitro, HRMCs were treated with safe doses of Nrf2 activators and prednisolone. The expression levels of Nrf2 and its target genes were measured using quantitative reverse transcription PCR and enzyme-linked immunosorbent assay. The anti-inflammatory effects of these compounds were assessed by measuring tumor necrosis factor alpha-induced cytokine secretion. Experimental LN was induced in female BALB/c mice by a single intraperitoneal injection of pristane. The urine albumin-to-creatinine ratio was measured at 20 weeks after injection. Pathological changes as well as protein and mRNA expression levels were assessed in the kidney obtained at the experimental end point. Oral administration of DMF or prednisolone to these mice was initiated after pristane injection.

Results

Nrf2 activators such as sulforaphane and DMF showed anti-inflammatory effects in HRMCs, whereas glucocorticoid (prednisolone) showed partial effects. Moreover, DMF ameliorated the development of kidney diseases in pristane-induced LN mice, whereas glucocorticoid had no effect.

Conclusions

Nrf2 activators showed stronger anti-inflammatory and organ-protective effects than glucocorticoid in the kidney. Thus, Nrf2 activators are potential therapeutic targets in glucocorticoid-resistant LN in humans.

Seasonal allergic rhinitis affects sinonasal microbiota

BACKGROUND

Microbes and allergens can stimulate the nasal mucosa, potentially leading to the development of acute bacterial rhinosinusitis (ABRS). This study was designed to determine if allergen exposure alters the sinonasal microbiome.

METHODS

We performed a parallel observational study of healthy adults with seasonal allergic rhinitis (SAR; grass or tree, n = 20) or nonallergic subjects (n = 19). Microbiota specimens were obtained by endoscopy from the middle meatus and vestibule before and during the relevant season and were analyzed by terminal restriction fragment length polymorphism analysis. Differences in bacterial microbiota were assessed by standard ecological measures of bacterial diversity. Quality of life and symptom scores were recorded, and nasal lavages for eosinophils were performed.

RESULTS

SAR subjects had increased nasal symptoms in season, impaired disease-specific quality of life, and increased nasal eosinophils, compared with no changes in nonallergic subjects. During the season, SAR subjects had a significantly greater variety of organisms in the middle meatus compared with nonallergic subjects (p < 0.036) and increased bacterial diversity (Shannon index, p < 0.013). We found a significant positive correlation between bacterial diversity in the middle meatus during the season and the nasal lavage eosinophil count of SAR subjects. There were no significant changes in the nasal vestibule (p > 0.05, all comparisons).

CONCLUSION

The interaction of allergy and microbiota may affect the sinonasal physiology, with broad implications for several airway diseases. Characterization of the specific organisms involved using next-generation sequencing may clarify the relationship between allergic inflammation and ABRS. This finding may help explain why allergic inflammation predisposes to ABRS.

Tulobuterol inhibits rhinovirus infection in primary cultures of human tracheal epithelial cells

A transdermal patch preparation of the β2 agonist tulobuterol has been designed to yield sustained β2 agonistic effects and has been used as a long-acting β2 agonist (LABA) in Japan. LABAs reduce the frequency of exacerbations of chronic obstructive pulmonary disease and bronchial asthma. However, inhibitory effects of LABAs on the replication of rhinovirus (RV), the major cause of exacerbations, have not been demonstrated. To examine the effects of tulobuterol on RV replication and on the production of the replication-induced pro-inflammatory cytokines, human tracheal epithelial cells were infected with a major group RV, type 14 rhinovirus (RV14). Tulobuterol reduced the RV14 titers and RNA levels; the concentrations of cytokines, including interleukin (IL)-1β, IL-6, and IL-8, in the supernatants; and susceptibility to RV14 infection. Tulobuterol reduced the expression of intercellular adhesion molecule-1 (ICAM-1), the receptor for RV14, and the number of acidic endosomes in the cells in which RV14 RNA enters the cytoplasm. Tulobuterol inhibited the activation of nuclear factor kappa B (NF-κB) proteins in nuclear extracts. A selective β2-adrenergic receptor antagonist, ICI 118551 [erythro-dl-1-(7-methylindan-4-yloxy)-3-isopropylaminobutan-2-ol], reversed the inhibitory effects of tulobuterol on the RV14 titers and RNA levels, the susceptibility to RV14 infection, cytokine production, and ICAM-1 expression. Tulobuterol may inhibit RV replication by reducing ICAM-1 expression and acidic endosomes and modulate airway inflammation during RV replication.

Effects of downregulation of aquaporin1 by peptidoglycan and lipopolysaccharide via MAPK pathways in MeT-5A cells

This study was designed to investigate the signaling pathway involved in aquaporin1 (AQP1) expression caused by peptidoglycan (PGN) from Staphylococcus aureus and lipopolysaccharide (LPS) in human pleural mesothelial cell lines (MeT-5A) in vitro. RT-PCR, immunoblot analysis, and immunofluorescence assay were used to determine the relative mRNA and protein levels of AQP1 caused by PGN and LPS in MeT-5A cells. Activation of MAPKs by PGN and LPS was reflected by detecting the phosphorylation constituents of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 using immunoblot. MAPKs inhibitors were used to determine the effects of PGN- and LPS-induced AQP1 expression by immunoblot. AQP1 transcription and protein expression were decreased by PGN and LPS in dose- and time-dependent manners in MeT-5A cells. Both PGN and LPS activated p38/ERK/JNK pathways in MeT-5A cells. Furthermore, downregulation of AQP1 expression by LPS was blocked by SB203580, SP600125, and PD98059, which are inhibitors of p38, JNK, and ERK1/2, respectively. In contrast, downregulation of AQP1 expression by PGN was blocked only by SB203580, not by SP600125 or PD98059, underlying the importance of p38 MAPK in the downregulation of AQP1 expression by PGN in MeT-5A cells. AQP1 expression was decreased by both PGN and LPS in dose- and time-dependent manners in MeT-5A cells. AQP1 expression was down-regulated by PGN via p38 MAPK pathway, while AQP1 expression was down-regulated by LPS via p38/JNK/ERK pathways.

Long acting beta2-agonist and corticosteroid restore airway glandular cell function altered by bacterial supernatant

BACKGROUND

Staphylococcus aureus releases virulence factors (VF) that may impair the innate protective functions of airway cells. The aim of this study was to determine whether a long-acting beta2 adrenergic receptor agonist (salmeterol hydroxynaphthoate, Sal) combined with a corticosteroid (fluticasone propionate, FP) was able to regulate ion content and cytokine expression by airway glandular cells after exposure to S. aureus supernatant.

METHODS

A human airway glandular cell line was incubated with S. aureus supernatant for 1 h and then treated with the combination Sal/FP for 4 h. The expression of actin and CFTR proteins was analyzed by immunofluorescence. Videomicroscopy was used to evaluate chloride secretion and X-ray microanalysis to measure the intracellular ion and water content. The pro-inflammatory cytokine expression was assessed by RT-PCR and ELISA.

RESULTS

When the cells were incubated with S. aureus supernatant and then with Sal/FP, the cellular localisation of CFTR was apical compared to the cytoplasmic localisation in cells incubated with S. aureus supernatant alone. The incubation of airway epithelial cells with S. aureus supernatant reduced by 66% the chloride efflux that was fully restored by Sal/FP treatment. We also observed that Sal/FP treatment induced the restoration of ion (Cl and S) and water content within the intracellular secretory granules of airway glandular cells and reduced the bacterial supernatant-dependent increase of pro-inflammatory cytokines IL8 and TNFalpha.

CONCLUSIONS

Our results demonstrate that treatment with the combination of a corticosteroid and a long-acting beta2 adrenergic receptor agonist after bacterial infection restores the airway glandular cell function. Abnormal mucus induced by defective ion transport during pulmonary infection could benefit from treatment with a combination of beta2 adrenergic receptor agonist and glucocorticoid.

Induction of IL-8 expression by Cordyceps militaris grown on germinated soybeans through lipid rafts formation and signaling pathways via ERK and JNK in A549 cells

AIM OF THE STUDY

In order to elucidate immunoregulatory mechanisms of Cordyceps militaris, a methanol extract of Cordyceps militaris grown on germinated soybeans was prepared and its immunoregulatory effect in the human lung epithelial cells was investigated by examining its ability to induce IL-8 expression.

MATERIALS AND METHODS

Cordyceps militaris grown on germinated soybeans was extracted with 80% methanol (GSC4M) and used for stimulation of a human lung epithelial cell-line, A549. An enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction were performed to examine the production of IL-8 protein and its mRNA, respectively. For the analysis of transcription factors regulating IL-8 transcriptional activation, the nuclear fraction was extracted from GSC4M-treated A549 cells and subjected to electrophoretic mobility shift assay.

RESULTS

GSC4M induced IL-8 protein secretion and its mRNA expression from A549 cells in a dose- and time-dependent manner. GSC4M-induced IL-8 expression was inhibited by an inhibitor for lipid rafts formation but not by that for clathrin-coated pits. In addition, signaling pathways for GSC4M-induced IL-8 expression were mediated through ERK and JNK but hardly through p38 kinase. Furthermore, GSC4M augmented the DNA-binding activity of the transcription factors AP-1, NF-IL6, and NF-kappaB, all of which are involved in the transcriptional activation of the IL-8 gene.

CONCLUSION

Cordyceps militaris grown on germinated soybeans stimulates lung epithelial cells to produce IL-8 through lipid rafts formation and signaling pathways via ERK and JNK.

Crosstalk in inflammation: the interplay of glucocorticoid receptor-based mechanisms and kinases and phosphatases

Glucocorticoids (GCs) are steroidal ligands for the GC receptor (GR), which can function as a ligand-activated transcription factor. These steroidal ligands and derivatives thereof are the first line of treatment in a vast array of inflammatory diseases. However, due to the general surge of side effects associated with long-term use of GCs and the potential problem of GC resistance in some patients, the scientific world continues to search for a better understanding of the GC-mediated antiinflammatory mechanisms. The reversible phosphomodification of various mediators in the inflammatory process plays a key role in modulating and fine-tuning the sensitivity, longevity, and intensity of the inflammatory response. As such, the antiinflammatory GCs can modulate the activity and/or expression of various kinases and phosphatases, thus affecting the signaling efficacy toward the propagation of proinflammatory gene expression and proinflammatory gene mRNA stability. Conversely, phosphorylation of GR can affect GR ligand- and DNA-binding affinity, mobility, and cofactor recruitment, culminating in altered transactivation and transrepression capabilities of GR, and consequently leading to a modified antiinflammatory potential. Recently, new roles for kinases and phosphatases have been described in GR-based antiinflammatory mechanisms. Moreover, kinase inhibitors have become increasingly important as antiinflammatory tools, not only for research but also for therapeutic purposes. In light of these developments, we aim to illuminate the integrated interplay between GR signaling and its correlating kinases and phosphatases in the context of the clinically important combat of inflammation, giving attention to implications on GC-mediated side effects and therapy resistance.

Virulence factors of Staphylococcus aureus induce Erk-MAP kinase activation and c-Fos expression in S9 and 16HBE14o- human airway epithelial cells

Part of the innate defense of bronchial epithelia against bacterial colonization is regulated secretion of salt, water, and mucus as well as defensins and cytokines involving MAP kinase activation and alterations in early gene expression. We tested two different types of immortalized human airway epithelial cells (S9, 16HBE14o-) for activation of Erk-type MAP kinases and for expression of c-Fos on treatment with Staphylococcus aureus culture supernatants from the stationary growth phase [optical density (OD)(540 nm) = 10] or with recombinant S. aureus hemolysins A and B (Hla, Hlb). OD10 supernatants activated Erk-type MAP kinases and c-Fos expression in a concentration-dependent manner. Hla induced Erk-type kinase phosphorylation in S9 but not in 16HBE14o- cells. Hlb induced Erk activation in either cell type. Basal and stimulated levels of Erk-type MAP kinase phosphorylation were sensitive to the Mek1 inhibitor PD-98059, indicating that the bacterial products activated the entire signaling cascade that coregulates IL-8 induction and secretion. While c-Fos expression was enhanced by OD10 supernatants, Hla, and Hlb in S9 cells, 16HBE14o- cells responded to OD10 supernatant and Hlb but not to Hla. In S9 cells, PD-98059 suppressed c-Fos upregulation by OD10 supernatant, Hla, or Hlb, indicating that c-Fos expression requires activation of Erk-type MAP kinases. In 16HBE14o- cells, however, c-Fos expression by OD10 supernatant was sensitive to PD-98059, while that induced by Hlb was not. This indicates that ingredients of OD10 supernatants other than Hla or Hlb are activating Erk-type MAP kinases in 16HBE14o- cells and that other intracellular signaling systems apart from Erk-type MAP kinases contribute to Hlb-mediated regulation of c-Fos. Thus interaction of bacterial factors with airway epithelial cells may be highly cell type specific.

Peptidoglycan-mediated IL-8 expression in human alveolar type II epithelial cells requires lipid raft formation and MAPK activation

Staphylococcus aureus, a major sepsis-causing Gram-positive bacterium, invades pulmonary epithelial cells and causes lung diseases. In the lung, alveolar type II epithelial cells play an important role in innate immunity by secreting chemokines and antimicrobial peptides upon bacterial infection whereas type I cells mainly function in gas-exchange. In this study, we investigated the ability of S. aureus peptidoglycan (PGN) to induce expression of a chemokine, IL-8, in a human alveolar type II epithelial cell line, A549. PGN induces IL-8 mRNA and protein expression in a dose- and time-dependent manner. Supplementation of soluble CD14 further enhanced the PGN-induced IL-8 expression. Interestingly, PGN-induced IL-8 expression was inhibited by nystatin, a specific inhibitor for lipid rafts, but not by chlorpromazine, a specific inhibitor for clathrin-coated pits. Furthermore, PGN-induced IL-8 expression was attenuated by inhibitors for MAP kinases such as ERK, p38 kinase, and JNK/SAPK, whereas no inhibitory effect was observed by inhibitors for reactive oxygen species or protein kinase C. Electrophoretic mobility shift assay demonstrates that PGN increased the DNA binding of the transcription factors, AP-1 and NF-kappaB while minimally, NF-IL6, all of which are involved in the transcription of IL-8. Taken together, these results suggest that PGN induces IL-8 expression in a CD14-enhanced manner in human alveolar type II epithelial cells, through the formation of lipid rafts and the activation of MAP kinases, which ultimately leads to activation of AP-1, NF-kappaB, and NF-IL6.