Pinus sylvestris L. and Syzygium aromaticum (L.) Merr. & L. M. Perry Essential Oils Inhibit Endotoxin-Induced Airway Hyperreactivity despite Aggravated Inflammatory Mechanisms in Mice

Scots pine (SO) and clove (CO) essential oils (EOs) are commonly used by inhalation, and their main components are shown to reduce inflammatory mediator production. The aim of our research was to investigate the chemical composition of commercially available SO and CO by gas chromatography–mass spectrometry and study their effects on airway functions and inflammation in an acute pneumonitis mouse model. Inflammation was evoked by intratracheal endotoxin and EOs were inhaled three times during the 24 h experimental period. Respiratory function was analyzed by unrestrained whole-body plethysmography, lung inflammation by semiquantitative histopathological scoring, myeloperoxidase (MPO) activity and cytokine measurements. α-Pinene (39.4%) was the main component in SO, and eugenol (88.6%) in CO. Both SO and CO significantly reduced airway hyperresponsiveness, and prevented peak expiratory flow, tidal volume increases and perivascular edema formation. Meanwhile, inflammatory cell infiltration was not remarkably affected. In contrast, MPO activity and several inflammatory cytokines (IL-1β, KC, MCP-1, MIP-2, TNF-α) were aggravated by both EOs. This is the first evidence that SO and CO inhalation improve airway function, but enhance certain inflammatory parameters. These results suggest that these EOs should be used with caution in cases of inflammation-associated respiratory diseases.

The Potential Role for Impaired Mucosal Integrity in the Generation of Esophageal Pain Using Capsaicin in Humans: An Explorative Study

INTRODUCTION

Esophageal pain is mediated by sensory nerves, most importantly by the activation of the transient receptor potential vanilloid 1 (TRPV1) capsaicin receptor. TRPV1 is activated and sensitized by a broad range of pungent compounds, as well as inflammatory mediators and tissue irritants. Luminal stressors are suggested to impair the barrier function, which results in consequent activation of these sensory nerve terminals and pain. In this study, we investigated the effect of the perfusion of capsaicin, a TRPV1 agonist, on mucosal impedance and pain in asymptomatic volunteers.

METHODS

Thirteen asymptomatic volunteers completed a single-blind, saline-controlled, randomized crossover study. Capsaicin or saline was perfused for 30 minutes in the distal esophagus. Visual analog scale pain intensity scores and intraluminal impedance indicating mucosal integrity were determined. Distal and proximal biopsies were obtained 10 minutes later to measure TRPV1 messenger RNA and TRPV1 immunopositivity, as well as the intercellular space area.

RESULTS

Capsaicin perfusion resulted in significantly greater pain intensity (P = 0.047) and impaired recovery of the mucosal impedance compared with saline-treated controls (P = 0.027). Pain response was significantly associated with decreased mucosal impedance. Similar dynamics were seen in the proximal esophagus, but mucosal impedance recovered entirely to the preinfusion values there. There was a significant association between mucosal impedance and intercellular space width in the distal esophagus. TRPV1 transcription and expression were not significantly altered within this observation period.

DISCUSSION

Esophageal capsaicin perfusion results in pain, which is likely to be explained by impaired mucosal impedance and defective restoration capacity in the distal esophagus.

Safety of chronic hypertonic bicarbonate inhalation in a cigarette smoke-induced airway irritation guinea pig model

BACKGROUND

Cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are often associated with airway fluid acidification. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene leads to impaired bicarbonate secretion contributing to CF airway pathology. Chronic cigarette smoke (CS) -the major cause of COPD- is reported to induce acquired CFTR dysfunction underlying airway acidification and inflammation. We hypothesize that bicarbonate-containing aerosols could be beneficial for patients with CFTR dysfunctions. Thus, we investigated the safety of hypertonic sodium bicarbonate (NaHCO3) inhalation in CS-exposed guinea pigs.

METHODS

Animals were divided into groups inhaling hypertonic NaCl (8.4%) or hypertonic NaHCO3 (8.4%) aerosol for 8 weeks. Subgroups from each treatment groups were further exposed to CS. Respiratory functions were measured at 0 and after 2, 4, 6 and 8 weeks. After 8 weeks blood tests and pulmonary histopathological assessment were performed.

RESULTS

Neither smoking nor NaHCO3-inhalation affected body weight, arterial and urine pH, or histopathology significantly. NaHCO3-inhalation did not worsen respiratory parameters. Moreover, it normalized the CS-induced transient alterations in frequency, peak inspiratory flow, inspiratory and expiratory times.

CONCLUSION

Long-term NaHCO3-inhalation is safe in chronic CS-exposed guinea pigs. Our data suggest that bicarbonate-containing aerosols might be carefully applied to CF patients.

Age-Related Decrease in Abdominal Pain and Associated Structural- and Functional Mechanisms: An Exploratory Study in Healthy Individuals and Irritable Bowel Syndrome Patients

Introduction: The world population is ageing, resulting in increased prevalence of age-related comorbidities and healthcare costs. Limited data are available on intestinal health in elderly populations. Structural and functional changes, including altered visceroperception, may lead to altered bowel habits and abdominal symptoms in healthy individuals and irritable bowel syndrome (IBS) patients. Our aim was to explore age-related changes in gastrointestinal symptoms and underlying mechanisms. Methods: In total, 780 subjects (IBS patients n = 463, healthy subjects n = 317) from two separate studies were included. Subjects were divided into different age groups ranging from young adult to elderly. Demographics and gastrointestinal symptom scores were collected from all participants using validated questionnaires. A subset of 233 IBS patients and 103 controls underwent a rectal barostat procedure to assess visceral hypersensitivity. Sigmoid biopsies were obtained from 10 healthy young adults and 10 healthy elderly. Expression of the visceral pain-associated receptors transient receptor potential (TRP) Ankyrin 1 (TRPA1) and Vanilloid 1 (TRPV1) genes were investigated by quantitative RT-PCR and immunofluorescence. Results: Both elderly IBS and healthy individuals showed significantly lower scores for abdominal pain (p < 0.001) and indigestion (p < 0.05) as compared to respective young adults. Visceral hypersensitivity was less common in elderly than young IBS patients (p < 0.001). Relative TRPA1 gene transcription, as well as TRPA1 and TRPV1 immunoreactivity were significantly lower in healthy elderly versus healthy young adults (p < 0.05). Conclusions: Our findings show an age-related decrease in abdominal pain perception. This may in part be related to decreased TRPA1 and/or TRPV1 receptor expression. Further studies are needed to reveal precise underlying mechanisms and the associations with intestinal health.

Inhibition of NHE-1 Increases Smoke-Induced Proliferative Activity of Barrett's Esophageal Cell Line

Several clinical studies indicate that smoking predisposes its consumers to esophageal inflammatory and malignant diseases, but the cellular mechanism is not clear. Ion transporters protect esophageal epithelial cells by maintaining intracellular pH at normal levels. In this study, we hypothesized that smoking affects the function of ion transporters, thus playing a role in the development of smoking-induced esophageal diseases. Esophageal cell lines were treated with cigarettesmoke extract (CSE), and the viability and proliferation of the cells, as well as the activity, mRNA and protein expression of the Na+/H+ exchanger-1 (NHE-1), were studied. NHE-1 expression was also investigated in human samples. For chronic treatment, guinea pigs were exposed to tobacco smoke, and NHE-1 activity was measured. Silencing of NHE-1 was performed by using specific siRNA. CSE treatment increased the activity and protein expression of NHE-1 in the metaplastic cells and decreased the rate of proliferation in a NHE-1-dependent manner. In contrast, CSE increased the proliferation of dysplastic cells independently of NHE-1. In the normal cells, the expression and activity of NHE-1 decreased due to in vitro and in vivo smoke exposure. Smoking enhances the function of NHE-1 in Barrett's esophagus, and this is presumably a compensatory mechanism against this toxic agent.

Protective effects of the novel amine-oxidase inhibitor multi-target drug SZV 1287 on streptozotocin-induced beta cell damage and diabetic complications in rats

Diabetes mellitus is a common metabolic disease leading to hyperglycemia due to insufficient pancreatic insulin production or effect. Amine oxidase copper containing 3 (AOC3) is an enzyme that belongs to the semicarbazide-sensitive amine oxidase family, which may be a novel therapeutic target to treat diabetic complications. We aimed to explore the effects of AOC3 inhibition and to test the actions of our novel AOC3 inhibitor multi-target drug candidate, SZV 1287, compared to a selective reference compound, LJP 1207, in an 8-week long insulin-controlled streptozotocin (STZ)-induced (60 mg/kg i.p.) rat diabetes model. Both AOC3 inhibitors (20 mg/kg, daily s.c. injections) were protective against STZ-induced pancreatic beta cell damage determined by insulin immunohistochemistry and radioimmunoassay, neuropathic cold hypersensitivity measured by paw withdrawal latency decrease from 0 °C water, and retinal dysfunction detected by electroretinography. SZV 1287 showed greater inhibitory effects on beta cell damage, and reduced retinal apoptosis shown by histochemistry. Mechanical hypersensitivity measured by aesthesiometry, cardiac dysfunction and nitrosative stress determined by echocardiography and immunohistochemistry/Western blot, respectively, serum Na⁺, K⁺, fructosamine, and urine microalbumin, creatinine, total protein/creatinine ratio alterations did not develop in response to diabetes. None of these parameters were influenced by the treatments except for SZV 1287 reducing serum fructosamine and LJP 1207 increasing urine creatinine. We provide the first evidence for protective effects of AOC3 inhibition on STZ-induced pancreatic beta cell damage, neuropathic cold hypersensitivity and diabetic retinal dysfunction. Long-term treatment with our novel multi-target analgesic candidate, SZV 1287, is safe and effective also under diabetic conditions.

Effects of Thymus vulgaris L., Cinnamomum verum J.Presl and Cymbopogon nardus (L.) Rendle Essential Oils in the Endotoxin-induced Acute Airway Inflammation Mouse Model

Thyme (TO), cinnamon (CO), and Ceylon type lemongrass (LO) essential oils (EOs) are commonly used for inhalation. However, their effects and mechanisms on inflammatory processes are not well-documented, and the number of in vivo data that would be important to determine their potential benefits or risks is low. Therefore, we analyzed the chemical composition and investigated the activity of TO, CO, and LO on airway functions and inflammatory parameters in an acute pneumonitis mouse model. The components of commercially available EOs were measured by gas chromatography-mass spectrometry. Airway inflammation was induced by intratracheal endotoxin administration in mice. EOs were inhaled during the experiments. Airway function and hyperresponsiveness were determined by unrestrained whole-body plethysmography on conscious animals. Myeloperoxidase (MPO) activity was measured by spectrophotometry from lung tissue homogenates, from which semiquantitative histopathological scores were assessed. The main components of TO, CO, and LO were thymol, cinnamaldehyde, and citronellal, respectively. We provide here the first evidence that TO and CO reduce inflammatory airway hyperresponsiveness and certain cellular inflammatory parameters, so they can potentially be considered as adjuvant treatments in respiratory inflammatory conditions. In contrast, Ceylon type LO inhalation might have an irritant effect (e.g., increased airway hyperresponsiveness and MPO activity) on the inflamed airways, and therefore should be avoided.

Subantimicrobial Dose Doxycycline Worsens Chronic Arthritis-Induced Bone Microarchitectural Alterations in a Mouse Model: Role of Matrix Metalloproteinases?

Background: Rheumatoid arthritis (RA) is a chronic inflammatory joint disease hallmarked by irreversible damage of cartilage and bone. Matrix metalloproteinases (MMPs) involved in connective tissue remodeling play an important role in this process. Numerous MMPs have been examined in humans and animals, but their functions are still not fully understood. Therefore, we investigated the role of MMPs in the K/BxN serum-transfer model of RA with the broad-spectrum MMP inhibitor subantimicrobial dose doxycycline (SDD) using complex in vivo and in vitro methodolgy.

Methods: Chronic arthritis was induced by repetitive i.p. injections of K/BxN serum in C57BL/6J mice. SDD was administered daily in acidified drinking water (0.5 mg/mL, 80 mg/kg) during the 30 days experimental period. Mechanonociceptive threshold of the paw was evaluated by aesthesiometry, grasping ability by grid test, arthritis severity by scoring, neutrophil myeloperoxidase activity by luminescence, vascular hyperpermeability and MMP activity by fluorescence in vivo imaging and the latter also by gelatin zymography, bone structure by micro-computed tomography (micro-CT). Plasma concentrations of doxycycline were determined by liquid chromatography-mass spectrometry analysis.

Results: K/BxN serum induced significant inflammatory signs, mechanical hyperalgesia, joint function impairment, increased myeloperoxidase activity and vascular hyperpermeability. Significant increase of MMP activity was also observed both in vivo and ex vivo with elevation of the 57–60, 75, and 92 kDa gelatinolytic isoforms in the arthritic ankle joints, but neither MMP activity nor any above described functional parameters were influenced by SDD. Most importantly, SDD significantly reduced bone mineral density in the distal tibia and enhanced the Euler number in the ankle. Arthritis-induced microarchitectural alterations demonstrating increased irregularity and cancellous bone remodeling, such as increased Euler number was significantly elevated by SDD in both regions.

Conclusion: We showed increase of various MMP activities in the joints by in vivo fluorescence imaging together with ex vivo zymography, and investigated their functional significance using the broad-spectrum MMP inhibitor SDD in the translational RA model. This is the first demonstration that SDD worsens arthritis-induced bone microarchitectural alterations, but it appears to be independent of MMP inhibition.

Role of TRPV1 and TRPA1 Ion Channels in Inflammatory Bowel Diseases: Potential Therapeutic Targets?

Inflammatory bowel diseases (IBD) have long been recognized to be accompanied by pain resulting in high morbidity. Transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) ion channels located predominantly on the capsaicin-sensitive sensory neurons play a complex role in hyperalgesia and neurogenic inflammation. This review provides an overview of their expression and role in intestinal inflammation, in particular colitis, that appears to be virtually inconsistent based on the thorough investigations of the last twenty years. However, preclinical results with pharmacological interventions, as well as scarcely available human studies, more convincingly point out the potential therapeutic value of TRPV1 and TRPA1 antagonists in colitis and visceral hypersensitivity providing future therapeutical perspectives through a complex, unique mechanism of action for drug development in IBD.

PPIs Prevent Aspirin-Induced Gastrointestinal Bleeding Better than H2RAs. A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

Aspirin is one of the most widely used medication for its analgesic and anti-platelet properties and thus a major cause for gastrointestinal (GI) bleeding. This study compared the preventive effect of histamine-2 receptor antagonists (H2RAs) and proton-pump inhibitors (PPIs) against chronic low-dose aspirin (LDA)-related GI bleeding and ulcer formation.

METHODS

Electronic databases of Pubmed, Embase and Cochrane Central Register of Controlled Trials were searched for human observations (randomised controlled trials and observational studies) comparing the long term effects of PPIs and H2RAs treatment in the prevention of GI bleeding or ulcer formation in patients on chronic LDA treatment listed up till September 30, 2016. Two independent authors searched databases using PICO questions (aspirin, H2RA, PPI, GI bleeding or ulcer), and reviewed abstracts and articles for comprehensive studies keeping adequate study quality. Data of weighted odds ratios were statistically evaluated using Comprehensive Metaanalysis (Biostat, Inc., Engelwood, MJ, USA), potential bias was checked.

RESULTS

Nine studies for GI bleeding and eight studies for ulcer formation were found meeting inclusion criteria, altogether 1,879 patients were included into review. The H2RAs prevented less effectively LDA-related GI bleeding (OR= 2.102, 95% CI: 1.008-4.385, p<0.048) and ulcer formation (OR= 2.257, 95% CI: 1.277-3.989, p<0.005) than PPIs.

CONCLUSION

The meta-analysis showed that H2RAs were less effective in the prevention of LDA-related GI bleeding and ulcer formation suggesting the preferable usage of PPIs in case of tolerance.

Long-Term Stress and Concomitant Marijuana Smoke Exposure Affect Physiology, Behavior and Adult Hippocampal Neurogenesis

Marijuana is a widely used recreational drug with increasing legalization worldwide for medical purposes. Most experimental studies use either synthetic or plant-derived cannabinoids to investigate the effect of cannabinoids on anxiety and cognitive functions. The aim of this study was to mimic real life situations where young people smoke cannabis regularly to relax from everyday stress. Therefore, we exposed young adult male NMRI mice to daily stress and concomitant marijuana smoke for 2 months and investigated the consequences on physiology, behavior and adult hippocampal neurogenesis. Animals were restrained for 6-h/day for 5-days a week. During the stress, mice were exposed to cannabis smoke for 2 × 30 min/day. We burned 2 “joints” (2 × 0.8 g marijuana) per occasion in a whole body smoking chamber. Cannabinoid content of the smoke and urine samples was measured by HPLC and SFC-MS/MS. Body weight gain was recorded daily and we did unrestrained, whole body plethysmography to investigate pulmonary functions. The cognitive performance of the animals was evaluated by the novel object recognition and Y maze tests. Anxietyrelated spontaneous locomotor activity and self-grooming were assessed in the open field test (OFT). Adult neurogenesis was quantified post mortem in the hippocampal dentate gyrus. The proliferative activity of the precursor cells was detected by the use of the exogenous marker 5-bromo-20-deoxyuridine. Treatment effects on maturing neurons were studied by the examination of doublecortin-positive neurons. Both stress and cannabis exposure significantly reduced body weight gain. Cannabis smoke had no effect on pulmonary functions, but stress delayed the maturation of several lung functions. Neither stress, nor cannabis smoke affected the cognitive functioning of the animals. Results of the OFT revealed that cannabis had a mild anxiolytic effect and markedly increased self-grooming behavior. Stress blocked cell proliferation in the dentate gyrus, but cannabis had no effect on this parameter. Marijuana smoke however had a pronounced impact on doublecortin-positive neurons influencing their number, morphology and migration. In summary, we report here that long-term stress in combination with cannabis smoke exposure can alter several health-related measures, but the present experimental design could not reveal any interaction between these two treatment factors except for body weight gain.

Integrative characterization of chronic cigarette smoke-induced cardiopulmonary comorbidities in a mouse model

Cigarette smoke-triggered inflammatory cascades and consequent tissue damage are the main causes of chronic obstructive pulmonary disease (COPD). There is no effective therapy and the key mediators of COPD are not identified due to the lack of translational animal models with complex characterization. This integrative chronic study investigated cardiopulmonary pathophysiological alterations and mechanisms with functional, morphological and biochemical techniques in a 6-month-long cigarette smoke exposure mouse model. Some respiratory alterations characteristic of emphysema (decreased airway resistance: Rl; end-expiratory work and pause: EEW, EEP; expiration time: Te; increased tidal mid-expiratory flow: EF50) were detected in anaesthetized C57BL/6 mice, unrestrained plethysmography did not show changes. Typical histopathological signs were peribronchial/perivascular (PB/PV) edema at month 1, neutrophil/macrophage infiltration at month 2, interstitial leukocyte accumulation at months 3-4, and emphysema/atelectasis at months 5-6 quantified by mean linear intercept measurement. Emphysema was proven by micro-CT quantification. Leukocyte number in the bronchoalveolar lavage at month 2 and lung matrix metalloproteinases-2 and 9 (MMP-2/MMP-9) activities in months 5-6 significantly increased. Smoking triggered complex cytokine profile change in the lung with one characteristic inflammatory peak of C5a, interleukin-1α and its receptor antagonist (IL-1α, IL-1ra), monokine induced by gamma interferon (MIG), macrophage colony-stimulating factor (M-CSF), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) at months 2-3, and another peak of interferon-γ (IFN-γ), IL-4, 7, 13, 17, 27 related to tissue destruction. Transient systolic and diastolic ventricular dysfunction developed after 1-2 months shown by significantly decreased ejection fraction (EF%) and deceleration time, respectively. These parameters together with the tricuspid annular plane systolic excursion (TAPSE) decreased again after 5-6 months. Soluble intercellular adhesion molecule-1 (sICAM-1) significantly increased in the heart homogenates at month 6, while other inflammatory cytokines were undetectable. This is the first study demonstrating smoking duration-dependent, complex cardiopulmonary alterations characteristic to COPD, in which inflammatory cytokine cascades and MMP-2/9 might be responsible for pulmonary destruction and sICAM-1 for heart dysfunction.

Marijuana smoke induces severe pulmonary hyperresponsiveness, inflammation, and emphysema in a predictive mouse model not via CB1 receptor activation

Sporadic clinical reports suggested that marijuana smoking induces spontaneous pneumothorax, but no animal models were available to validate these observations and to study the underlying mechanisms. Therefore, we performed a systematic study in CD1 mice as a predictive animal model and assessed the pathophysiological alterations in response to 4-mo-long whole body marijuana smoke with integrative methodologies in comparison with tobacco smoke. Bronchial responsiveness was measured with unrestrained whole body plethysmography, cell profile in the bronchoalveolar lavage fluid with flow cytometry, myeloperoxidase activity with spectrophotometry, inflammatory cytokines with ELISA, and histopathological alterations with light microscopy. Daily marijuana inhalation evoked severe bronchial hyperreactivity after a week. Characteristic perivascular/peribronchial edema, atelectasis, apical emphysema, and neutrophil and macrophage infiltration developed after 1 mo of marijuana smoking; lymphocyte accumulation after 2 mo; macrophage-like giant cells, irregular or destroyed bronchial mucosa, goblet cell hyperplasia after 3 mo; and severe atelectasis, emphysema, obstructed or damaged bronchioles, and endothelial proliferation at 4 mo. Myeloperoxidase activity, inflammatory cell, and cytokine profile correlated with these changes. Airway hyperresponsiveness and inflammation were not altered in mice lacking the CB1 cannabinoid receptor. In comparison, tobacco smoke induced hyperresponsiveness after 2 mo and significantly later caused inflammatory cell infiltration/activation with only mild emphysema. We provide the first systematic and comparative experimental evidence that marijuana causes severe airway hyperresponsiveness, inflammation, tissue destruction, and emphysema, which are not mediated by the CB1 receptor.

Low intensity, long term exposure to tobacco smoke inhibits hippocampal neurogenesis in adult mice

Previous data have shown that high dose of nicotine administration or tobacco smoke exposure can reduce cell formation and the survival rate of adult-born neurons in the dentate gyrus. Here, we subjected adult mice to low intensity cigarette smoke exposure over long time periods. We did a 2×30min/day smoke exposure with two cigarettes per occasion over 1- or 2-months. Subsequently, we carried out a systematic quantitative histopathological analysis to assess the number of newborn neurons in the dentate gyrus. To investigate cell proliferation, the exogenous marker 5-bromo-2'-deoxyuridine (BrdU) was administered on the last experimental day and animals were sacrificed 2h later. To investigate the effect of tobacco smoke on the population of immature neurons, we quantified the number of doublecortin-positive (DCX+) neurons in the same animals. We found that exposing animals to cigarette smoke for 1- or 2-months had no influence on cell proliferation rate, but significantly reduced the number of DCX-positive immature neurons. Our tobacco smoke exposure regimen caused no substantial changes in respiratory functions, but histopathological analysis of the pulmonary tissue revealed a marked perivascular/peribronchial edema formation after 1-month and signs of chronic pulmonary inflammation after 2-months of cigarette smoke exposure. These data demonstrate that even mild exposure to cigarette smoke, without significantly affecting respiratory functions, can have a negative effect on adult-born neurons in the dentate gyrus, when applied over longer time periods. Our data indicate that besides nicotine other factors, such as inflammatory mediators, may also contribute to this effect.