Autocrine Acetylcholine, Induced by IL-17A via NFκB and ERK1/2 Pathway Activation, Promotes MUC5AC and IL-8 Synthesis in Bronchial Epithelial Cells

Endogenous Cholinergic System Involved in Peripheral Analgesic Control in Mice Is Activated by TNF-α, CXCL-1, and IL-1β

INTRODUCTION

Tissue injury results in the release of inflammatory mediators, including a cascade of algogenic substances, which contribute to the development of hyperalgesia. During this process, endogenous analgesic substances are peripherally released to counterbalance hyperalgesia. The present study aimed to investigate whether inflammatory mediators TNF-α, IL-1β, CXCL1, norepinephrine (NE), and prostaglandin E2 (PGE2) may be involved in the deflagration of peripheral endogenous modulation of inflammatory pain by activation of the cholinergic system.

METHODS

Male Swiss mice were subjected to paw withdrawal test. All the substances were injected via the intraplantar route.

RESULTS

The main findings of this study were as follows: (1) carrageenan (Cg), TNF-α, CXCL-1, IL1-β, NE, and PGE2 induced hyperalgesia; (2) the acetylcholinesterase enzyme inhibitor, neostigmine, reversed the hyperalgesia observed after Cg, TNF-α, CXCL-1, and IL1-β injection; (3) the non-selective muscarinic receptor antagonist, atropine, and the selective muscarinic type 1 receptor (m1AChr) antagonist, telenzepine, potentiated the hyperalgesia induced by Cg and CXCL-1; (4) mecamylamine, a non-selective nicotinic receptor antagonist, potentiated the hyperalgesia induced by Cg, TNF-α, CXCL-1, and IL1-β; (5) Cg, CXCL-1, and PGE2 increased the expression of the m1AChr and nicotinic receptor subunit α4protein.

CONCLUSION

These results suggest that the cholinergic system may modulate the inflammatory pain induced by Cg, PGE2, TNF-α, CXCL-1, and IL1-β.

Acute infection with Brachyspira hyodysenteriae affects mucin expression, glycosylation, and fecal MUC5AC

Introduction

Infection with strongly β-hemolytic strains of Brachyspira hyodysenteriae leads to swine dysentery (SD), a production-limiting disease that causes mucohemorrhagic diarrhea and typhlocolitis in pigs. This pathogen has strong chemotactic activity toward mucin, and infected pigs often have a disorganized mucus layer and marked de novo expression of MUC5AC, which is not constitutively expressed in the colon. It has been shown that fucose is chemoattractant for B. hyodysenteriae, and a highly fermentable fiber diet can mitigate and delay the onset of SD.

Methods

We used lectins targeting sialic acids in α-2,6 or α-2,3 linkages, N-acetylglucosamine (GlcNAc), α-linked L-fucose, and an immunohistochemical stain targeting N-glycolylneuraminic acid (NeuGc) to investigate the local expression of these mucin glycans in colonic tissues of pigs with acute SD. We used a commercial enzyme-linked immunosorbent assay (ELISA) to quantify fecal MUC5AC in infected pigs and assess its potential as a diagnostic monitoring tool and RNA in situ hybridization to detect IL-17A in the colonic mucosa.

Results

Colonic mucin glycosylation during SD has an overall increase in fucose, a spatially different distribution of GlcNAc with more expression within the crypt lumens of the upper colonic mucosa, and decreased expression or a decreased trend of sialic acids in α-2,6 or α-2,3 linkages, and NeuGc compared to the controls. The degree of increased fucosylation was less in the colonic mucosa of pigs with SD and fed the highly fermentable fiber diet. There was a significant increase in MUC5AC in fecal and colonic samples of pigs with SD at the endpoint compared to the controls, but the predictive value for disease progression was limited.

Discussion

Fucosylation and the impact of dietary fiber may play important roles in the pathogenesis of SD. The lack of predictive value for fecal MUC5AC quantification by ELISA is possibly due to the presence of other non-colonic sources of MUC5AC in the feces. The moderate correlation between IL-17A, neutrophils and MUC5AC confirms its immunoregulatory and mucin stimulatory role. Our study characterizes local alteration of mucin glycosylation in the colonic mucosa of pigs with SD after B. hyodysenteriae infection and may provide insight into host-pathogen interaction.

Human lung cell models to study aerosol delivery - considerations for model design and development

Human lung tissue models range from simple monolayer cultures to more advanced three-dimensional co-cultures. Each model system can address the interactions of different types of aerosols and the choice of the model and the mode of aerosol exposure depends on the relevant scenario, such as adverse outcomes and endpoints of interest. This review focuses on the functional, as well as structural, aspects of lung tissue from the upper airway to the distal alveolar compartments as this information is relevant for the design of a model as well as how the aerosol properties determine the interfacial properties with the respiratory wall. The most important aspects on how to design lung models are summarized with a focus on (i) choice of appropriate scaffold, (ii) selection of cell types for healthy and diseased lung models, (iii) use of culture condition and assembly, (iv) aerosol exposure methods, and (v) endpoints and verification process. Finally, remaining challenges and future directions in this field are discussed.

Interleukin-17A mediates tobacco smoke-induced lung cancer epithelial-mesenchymal transition through transcriptional regulation of ΔNp63α on miR-19

Interleukin-17A (IL-17A) is an essential inflammatory cytokine in the progress of carcinogenesis. Tobacco smoke (TS) is a major risk factor of lung cancer that influences epithelial-mesenchymal transition (EMT) process. However, the potential mechanism by which IL-17A mediates the progression of lung cancer in TS-induced EMT remains elusive. In the present study, it was revealed that the IL-17A level was elevated in lung cancer tissues, especially in tumor tissues of cases with experience of smoking, and a higher IL-17A level was correlated with induction of EMT in those specimens. Moreover, the expression of ΔNp63α was increased in IL-17A-stimulated lung cancer cells. ΔNp63α functioned as a key oncogene that bound to the miR-17-92 cluster promoter and transcriptionally increased the expression of miR-19 in lung cancer cells. Overexpression of miR-19 promoted EMT in lung cancer with downregulation of E-cadherin and upregulation of N-cadherin, while its inhibition suppressed EMT. Finally, the upregulated levels of IL-17A, ΔNp63α, and miR-19 along with the alteration of EMT-associated biomarkers were found in lung tissues of TS-exposed mice. Taken together, the abovementioned results suggest that IL-17A increases ΔNp63α expression, transcriptionally elevates miR-19 expression, and promotes TS-induced EMT in lung cancer. These findings may provide a new insight for the identification of therapeutic targets for lung cancer.

A pilot study of spray cryotherapy effects on airway secretions

Spray cryotherapy (SCT) is a new transbronchial approach that disrupts epithelial cells by freezing. However, there are limited data addressing the effect of SCT on airway secretion. The aim of this study was to evaluate if SCT effect on airway secretion and the possible mechanism in canines. Fifteen labradors were randomly scheduled SCT or sham operation. Six labradors were scheduled SCT for a short-time observation, and six for a long-time observation, the remaining three received sham operation as control. Lung tissues were harvested for PAS staining. Mucin, MUC5AC and acetylcholine in bronchoalveolar lavage fluid (BALF) were analyzed by enzyme-linked immunosorbent assay (ELISA). CHRM3 and Mucin 5AC (MUC5AC) expressions in the lung tissues were analyzed by immunohistochemistry. MUC5AC mRNA expression was analyzed by rt-PCR. From 0 day to 30 days after SCT, the ratio of PAS positive cells to total bronchial epithelial cells, the average optical density of MUC5AC + by immunohistochemistry, the protein expression of MUC5AC, acetylcholine in BALF decreased compared with that of control group (p < 0.05). The average optical density of CHRM3+ by immunohistochemistry were decreased from 0 day to 7 days after SCT (p < 0.05) compared with control group. In conclusion, SCT was able to reduce the PAS-, MUC5AC- and CHRM3-positive cells in the lung tissue and acetylcholine in BALF, suggesting that SCT may prove to be a beneficial way in mucus excessive production in airway and acetylcholine-CHRM3 pathway may one possible mechanism.

Rhubarb extract relieves constipation by stimulating mucus production in the colon and altering the intestinal flora

BACKGROUND

Constipation, mainly characterized by the difficulty in defecation, is a clinical symptom caused by a variety of factors. It can be manifested as normal or slow colonic transport abnormalities, which can occur alone or concurrently with defecation disorders. As there is not uniform definition and assessment standard, no clear plan could be used for the treatment of constipation. Although rhubarb, a traditional Chinese medicine, plays a therapeutic role in diseases involving constipation symptoms, the detailed mechanism of it in treating constipation remains unclear.

METHODS

A model of constipation-induced by diphenoxylate was prepared. Immunofluorescent staining was used to detect the expression of mucin 2 (MUC2), calnexin and chymase in colon. Western blotting was used to detect changes of tryptase and calnexin in the colon. And real-time polymerase chain reaction (PCR) was utilized to detect the changes of immunoglobulin-binding protein (Bip), X-box binding protein 1 (Xbp1) and C/EBP homologous protein (CHOP) of colonic goblet cells in mRNA levels. ELISA and biochemical kits were utilized to detect the changes of MUC2, Trefoil factor 3 (TFF3), acetylcholine, histamine and C-C motif chemokine ligand 5 (CCL5) in the colon. And the changes of colonic mucosa and intestinal flora of constipation model mice caused by rhubarb extract (RE) were analyzed to identify the mechanism of RE on the treatment of constipation.

RESULTS

RE promotes the secretion of colonic mucus by recruiting mast cells and enhancing the content of histamine and Ach in the mice colon. In the process, RE causes up-regulation of Bip and CHOP mRNA expression and down-regulation of Xbp1 and Xbp1s mRNA expression that induces ER stress of colonic epithelium associated with changes in the intestinal flora diversity and short-chain fatty acids content.

CONCLUSION

RE could relieve constipation by promoting the secretion of colonic mucus via mast cells activation and improving the intestinal microenvironment.

Short-chain fatty acids exert opposite effects on the expression and function of p-glycoprotein and breast cancer resistance protein in rat intestine

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are involved in intestinal barrier. Short-chain fatty acids (SCFAs) play important roles in maintaining intestinal barrier. In this study we explored how SCFAs affected the expression and function of intestinal P-gp and BCRP in rats. Rats received 150 mM acetate, propionate or butyrate in drinking water for 4 weeks. In SCFA-treated rats, the expression and function of intestinal P-gp were decreased, but those of intestinal BCRP were increased; intestinal p-p65 was also decreased, which was positively related to P-gp protein expression. Among the three SCFAs tested, butyrate exhibited the strongest induction or inhibitory effect, followed by propionate and acetate. Similar results were observed in mouse primary enterocytes and Caco-2 cells treated with acetate (5 mM), propionate (2 mM), or butyrate (1 mM). In Caco-2 cells, addition of butyrate, vorinostat, and valproate (two classic HDAC inhibitors), Bay117082 (selective inhibitor of NF-κB activation) or NF-κB p65 silencing significantly decreased the expression of P-gp and the level of phosphorylated p65 (p-p65). Furthermore, butyrate attenuated the expression of P-gp and p-p65 induced by TNF-α (NF-κB activator) and theophylline (HDAC activator). However, vorinostat, valproate, Bay117082, TNF-α or p65 silencing hardly affected BCRP protein expression. But GW9662 (selective PPARγ antagonist) or PPARγ silencing abolished BCRP induction by butyrate and troglitazone (PPARγ agonist). SCFAs-treated rats showed higher intestinal protein expression of PPARγ, which was positively related to BCRP protein expression. Butyrate increased plasma exposure of fexofenadine but decreased that of rosuvastatin following oral dose to rats. In conclusion, SCFAs exert opposite effects on the expression and function of intestinal P-gp and BCRP; butyrate downregulated P-gp expression and function possibly via inhibiting HDAC/NF-κB pathways; butyrate induced BCRP expression and function partly via PPARγ activation.

Cholinergic signalling mechanisms and early implant healing phases in healthy versus generalized aggressive periodontitis patients: A prospective, case-control study

AIMS

Periodontal diseases negatively affect implant osseointegration. Perturbations in non-neuronal cholinergic signalling mechanisms are associated with periodontitis; however, their role in generalized aggressive periodontitis (GAgP) is unknown. The aim of this prospective case-control study was to determine the relationship between non-neuronal cholinergic signalling mechanisms, secreted Ly-6/uPAR-related protein-1 (SLURP-1), interleukin-17 (IL-17) family cytokines and healing of dental implants in health and GAgP.

MATERIAL AND METHODS

Thirteen GAgP patients and seven periodontally healthy individuals (PH) were recruited. Peri-implant crevicular fluid (PICF) was obtained at baseline and 1 month post-placement. Acetylcholine (ACh) levels and cholinesterase activity were determined biochemically. SLURP-1, IL-17A and IL-17E levels were determined by ELISA. Marginal bone loss (MBL) at 1 and 6 months post-placement was determined radiographically.

RESULTS

The concentration of ACh, cholinesterase activity and IL-17A levels was elevated in PICF of patients with GAgP compared to PH individuals at baseline and 1 month post-placement. The concentration of ACh and cholinesterase activity levels in PICF correlated with levels of IL-17A and MBL around implants 1 month post-placement in patients with GAgP.

CONCLUSIONS

Non-neuronal cholinergic mechanisms may play a role in the aetiopathogenesis of GAgP and may directly or indirectly, through modulation of IL-17A, influence early implant osseointegration and potential long-term implant survival.

The mode of action of anticholinergics in asthma

Acetylcholine binds to muscarinic receptors to play a key role in the pathophysiology of asthma, leading to bronchoconstriction, increased mucus secretion, inflammation and airway remodelling. Anticholinergics are muscarinic receptor antagonists that are used in the treatment of chronic obstructive pulmonary disease and asthma. Recent in vivo and in vitro data have increased our understanding of how acetylcholine contributes to the disease manifestations of asthma, as well as elucidating the mechanism of action of anticholinergics. This review assesses the latest literature on acetylcholine in asthma pathophysiology, with a closer look at its role in airway inflammation and remodelling. New insights into the mechanism of action of anticholinergics, their effects on airway remodelling, and a review of the efficacy and safety of long-acting anticholinergics in asthma treatment will also be covered, including a summary of the latest clinical trial data.

Pre-clinical data suggest that anticholinergics can reduce acetylcholine-induced airway inflammation and remodellinghttp://ow.ly/xqAQ30loP8F

Crosstalk between mAChRM3 and β2AR, via acetylcholine PI3/PKC/PBEP1/Raf-1 MEK1/2/ERK1/2 pathway activation, in human bronchial epithelial cells after long-term cigarette smoke exposure

BACKGROUND

Cigarette smoke extract (CSE) affects the expression of non-neuronal components of cholinergic system in bronchial epithelial cells and, as PEBP1/Raf-mediated MAPK1/2 and ERK1/2 pathway, promotes inflammation and oxidative stress.

AIMS

We studied whether Acetylcholine (ACh) is involved in the mechanism of crosstalk between mAChRM3 and β2Adrenergic receptors (β2AR) promoting, via PI3/PKC/PBEP1/Raf/MEK1/2/ERK1/2 activation, β2AR desensitization, inflammation and, oxidative stress in a bronchial epithelial cell line (16HBE) after long-term exposure to cigarette smoke extract (LECSE).

METHODS

We evaluated mAChRM3 and Choline Acetyltransferase (ChAT) expression, ACh production, PEBP1, ERk1/2, and β2AR phosphorylation, as well as NOX-4, ROS production and IL-8 release in 16HBE after LECSE. The inhibitory activity of Hemicholinium (HCh-3) (a potent choline uptake blocker), LY294002 (a highly selective inhibitor of PI3 kinase), Tiotropium (Spiriva®) (anticholinergic drug) and Olodaterol (β2AR agonist), were tested in 16HBE after LECSE.

RESULTS

mAChRM3, ChAT, ACh activity, pPEBP1, pβ2AR, pERK1/2, ROS, NOX-4 and IL-8 increased after LECSE in 16HBE LECSE compared to untreated cells. HCh-3 and LY294002 (alone or in combination) as well as Tiotropium (Spiriva®) or Olodaterol (alone or in combination) all reduced the levels of pPEBP1, pβ2AR, pERK1/2, ROS, NOX-4, and IL-8 in 16HBE LECSE compared to untreated cells.

CONCLUSIONS

LECSE promotes ACh production which enhances PI3/PKC/PEBP1/Raf-ERK1/2 pathway activation, heterologous β2AR desensitization, as well as release of inflammatory and oxidative mediators in bronchial epithelial cells. The use of anticholinergic drugs and long-acting β2-agonists, alone or in combination may be dampen these inflammatory mechanisms when used in combination in some epithelial cell types.

Tiotropium Respimat Add-on Is Efficacious in Symptomatic Asthma, Independent of T2 Phenotype

BACKGROUND

Adding tiotropium to existing inhaled corticosteroid (ICS) maintenance therapy with or without a long-acting β₂-agonist (LABA) has been shown to be beneficial in patients with symptomatic asthma.

OBJECTIVE

To assess whether responses to tiotropium Respimat add-on therapy were influenced by patients' T2 status.

METHODS

In this exploratory study, data from 4 phase III trials were analyzed: once-daily tiotropium 5 μg or placebo as add-on to ICS + LABA (PrimoTinA-asthma; 2 replicate trials; NCT00772538/NCT00776984; n = 912); once-daily tiotropium 5 μg or 2.5 μg, twice-daily salmeterol 50 μg, or placebo as add-on to ICS (MezzoTinA-asthma; 2 replicate trials; NCT01172808/NCT01172821; n = 2100). The prespecified efficacy outcomes of these studies have been reported previously. Here, further exploratory subgroup analyses were performed to study whether these coprimary end points were influenced by serum IgE levels, blood eosinophil counts, and clinician judgment of allergic asthma. In addition, for the continuous parameters, namely, IgE and blood eosinophils, their influence on the treatment effect was modeled over the whole range of values.

RESULTS

Tiotropium was efficacious in improving peak FEV₁ within 3 hours postdose and trough FEV₁, independent of T2 status. Tiotropium significantly reduced the risk of severe asthma exacerbations and asthma worsening, independent of T2 phenotype; Cox regression modeling supported a beneficial effect of tiotropium on exacerbations, independent of IgE levels or eosinophil counts. Numerical improvements in the 7-question Asthma Control Questionnaire (ACQ-7) responder rate with tiotropium versus placebo were observed in T2_high and T2_low patients; logistic regression modeling provided further evidence for improvement in ACQ-7 responder rates with tiotropium, independent of IgE levels or eosinophil counts.

CONCLUSIONS

The results of our exploratory analyses suggest that the improvements seen with tiotropium Respimat as add-on to ICS ± LABA in patients with symptomatic asthma on lung function, exacerbation risk, and symptom control are independent of T2 phenotype.

Tiotropium inhibits mucin production stimulated by neutrophil elastase but not by IL-13

Tiotropium, a muscarinic antagonist, is approved for the treatment of chronic obstructive pulmonary disease and poorly controlled asthma. Because mucus hypersecretion is characteristic of both of these diseases, and muscarinic agonists stimulate mucus secretion, we hypothesized that tiotropium would attenuate airway MUC5AC expression. We grew normal human bronchial epithelial (NHBE) cells to a goblet cell phenotype with 1 or 5 ng/mL of IL-13 and exposed these cells to 10 nM tiotropium or excipient for the full 14 days. Normally differentiated NHBE cells (without IL-13) were exposed to neutrophil elastase (NE) 1 × 10^-7 or 5 × 10^-7 M for 1 h. MUC5AC was measured by quantitative PCR and ELISA. Acetylcholine production by the epithelium was evaluated by quantitative PCR and by choline/acetylcholine quantification. Tiotropium had no effect on IL-13-stimulated MUC5AC, but attenuated MUC5AC stimulated by NE (p = 0.007 at 5 × 10^-7 M). IL-13 increased CarAT mRNA (p < 0.001 at 5 ng/mL) and acetylcholine concentration in the medium (p = 0.018 at 5 ng/mL), while NE had no effect. Tiotropium had no direct effect on IL-13 or NE-induced CarAT or acetylcholine concentration. Tiotropium decreased MUC5AC stimulated by NE, but had no effect on MUC5AC stimulated by IL-13. These results may be due to IL-13, but not NE, increasing acetylcholine production.

Mxi1-0 regulates the growth of human umbilical vein endothelial cells through extracellular signal-regulated kinase 1/2 (ERK1/2) and interleukin-8 (IL-8)-dependent pathways

Mxi1 plays an important role in the regulation of cell proliferation. Mxi1-0, a Mxi1 isoform, has a different N-terminal amino acid sequence, intracellular location and expression profile from Mxi1. However, the precise role of Mxi1-0 in cell proliferation and the molecular mechanism underlying its function remain poorly understood. Here, we showed that Mxi1-0 suppression decreased the proliferation of human umbilical vein endothelial cells (HUVECs) along with cell accumulation in the G2/M phase. Mxi1-0 suppression also significantly decreased the expression and secretion of interleukin (IL-8). Neutralizing IL-8 in conditioned medium (CM) from Mxi1-0-overexpressed HUVECs significantly eliminated CM-induced proliferation of HUVECs. In addition, Mxi1-0 suppression significantly decreased the activity of MAP kinase ERK1/2. Treatment of HUVECs with U0126, an ERK1/2 signaling inhibitor, attenuated autocrine production of IL-8 induced by Mxi1-0 overexpression. On the other hand, Mxi1-0 overexpression-induced IL-8 increased the level of phosphorylated ERK1/2 in HUVECs, and such increasing was diminished in cells incubated with CM, which neutralized with anti-IL-8 antibody. Taken together, our results suggest that Mxi1-0 regulates the growth of HUVECs via the IL-8 and ERK1/2 pathways, which apparently reciprocally activate each other.