Interleukin-8 increases acetylcholine response of rat intestinal segments

Systemic Cytokine Expression in Diabetes Is Associated with Prolonged Gastrointestinal Transit Times and Cardinal Gastroparesis Symptoms

Gastroenteropathy is a common complication in diabetes associated with damages to the enteric nervous system. Systemic low-grade inflammation facilitates neurotoxicity, and associations with peripheral and autonomic neuropathy have been reported. However, less is known of associations with gastroenteropathy. To explore the area cross-sectionally, we included individuals with diabetes (type 1: 56, type 2: 100) and 21 healthy controls. Serum levels of interleukin (IL)-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, and interferon (IFN)-γ were measured by multiplex technology. Segmental gastrointestinal transit times were assessed by wireless motility capsule investigations. Symptoms of gastroparesis were rated on Gastroparesis Cardinal Symptom Index questionnaires. Compared to healthy, levels of TNF-α were decreased in type 1 diabetes and increased in type 2 diabetes, while colonic transit time was increased (all p < 0.05). In diabetes, associations between IL-8 and prolonged gastric emptying (odds ratio (OR) 1.07, p = 0.027) and between IL-10 and prolonged colonic transit (OR 29.99, p = 0.013) were seen. Inverse correlations between IL-6 and nausea/vomiting (rho = −0.19, p = 0.026) and bloating (rho = −0.29; p < 0.001) were found. These findings indicate a plausible interaction between inflammation and the enteric nervous system in diabetes, which raises the question of whether anti-inflammatory strategies could be applied in management of diabetic gastroenteropathy.

The Role of Inflammatory Mediators in the Development of Gastrointestinal Motility Disorders

Feeding intolerance and the development of ileus is a common complication affecting critically ill, surgical, and trauma patients, resulting in prolonged intensive care unit and hospital stays, increased infectious complications, a higher rate of hospital readmission, and higher medical care costs. Medical treatment for ileus is ineffective and many of the available prokinetic drugs have serious side effects that limit their use. Despite the large number of patients affected and the consequences of ileus, little progress has been made in identifying new drug targets for the treatment of ileus. Inflammatory mediators play a critical role in the development of ileus, but surprisingly little is known about the direct effects of inflammatory mediators on cells of the gastrointestinal tract, and many of the studies are conflicting. Understanding the effects of inflammatory cytokines/chemokines on the development of ileus will facilitate the early identification of patients who will develop ileus and the identification of new drug targets to treat ileus. Thus, herein, we review the published literature concerning the effects of inflammatory mediators on gastrointestinal motility.

Validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport of drugs

BACKGROUND AND PURPOSE

Lymphatic transport of drugs after oral administration is an important mechanism for absorption of highly lipophilic compounds. Direct measurement in lymph duct cannulated animals is the gold standard method, but non-invasive cycloheximide chylomicron flow blocking method has gained popularity recently. However, concerns about its reliability have been raised. The aim of this work was to investigate the validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport using model compounds with high to very high lipophilicity, that is, abiraterone and cinacalcet.

EXPERIMENTAL APPROACH

Series of pharmacokinetic studies were conducted with abiraterone acetate and cinacalcet hydrochloride after enteral/intravenous administration to intact, lymph duct cannulated and/or cycloheximide pre-treated rats.

KEY RESULTS

Mean total absolute oral bioavailability of abiraterone and cinacalcet was 7.0% and 28.7%, respectively. There was a large and significant overestimation of the lymphatic transport extent by the cycloheximide method. Mean relative lymphatic bioavailability of abiraterone and cinacalcet in cycloheximide method was 28-fold and 3-fold higher than in cannulation method, respectively.

CONCLUSION AND IMPLICATIONS

Cycloheximide chylomicron flow blocking method did not provide reliable results on lymphatic absorption and substantially overestimated lymphatic transport for both molecules, that is, abiraterone and cinacalcet. This non-invasive method should not be used for the assessment of lymphatic transport and previously obtained data should be critically revised.

Evaluation of therapeutic effect of low dose naltrexone in experimentally-induced Crohn's disease in rats

BACKGROUND AND AIM

Crohn's disease is a relapsing inflammatory condition afflicting the digestive tract. Drugs used for treatment of Crohn's disease may be associated with serious side effects. Endogenous opioid peptides modulate inflammatory cytokine production. Opioid antagonists have been shown to play a role in healing and repair of tissues. This work was designed to detect the possible beneficial effects of opioid antagonist naltrexone in indomethacin-induced Crohn's disease in rats.

EXPERIMENTAL APPROACH

Enteritis was induced in male albino rats by two subcutaneous injection of indomethacin in a dose of 7.5mg/kg 24h apart started on day one. Salfasalazine, naltrexone and their combination were administered orally from day one of induction of enteritis to day 10. Disease activity index, serum levels of C-reactive protein and tumor necrosis factor-α, macroscopic and microscopic pathological scores and in vitro motility studies were evaluated.

RESULTS

Induction of enteritis resulted in significant increase of disease activity index, significant elevation of serum levels of C-reactive protein and tumor necrosis factor-α, significant deterioration of pathological scores and significant increase in the mean contractility response of the isolated ileal segments compared with normal untreated rats. Treatment with sulfasalazine, low dose of natrexone or their combination resulted in significant improvement of all measured parameters compared with enteritis group.

CONCLUSION

The current finding could provide new interesting opportunity for developing new therapeutic approaches for treatment of Crohn's disease. Use of naltrexone, especially in small dose, has little side effects making it of interest for treatment of Crohn's disease. Also, it provides the possibility of reduced doses of other drugs if it is used as combined therapy.

Interleukin-8: novel roles in human airway smooth muscle cell contraction and migration

In patients with cystic fibrosis (CF) and asthma, elevated levels of interleukin-8 (IL-8) are found in the airways. IL-8 is a CXC chemokine that is a chemoattractant for neutrophils through CXCR1 and CXCR2 G protein-coupled receptors. We hypothesized that IL-8 acts directly on airway smooth muscle cells (ASMC) in a way that may contribute to the enhanced airway responsiveness and airway remodeling observed in CF and asthma. The aim of this study was to determine whether human ASMC (HASMC) express functional IL-8 receptors (CXCR1 and CXCR2) linked to cell contraction and migration. Experiments were conducted on cells harvested from human lung specimens. Real-time PCR and fluorescence-activated cell sorting analysis showed that HASMC expressed mRNA and protein for both CXCR1 and CXCR2. Intracellular Ca2+ concentration ([Ca2+]i) increased from 115 to 170 nM in response to IL-8 (100 nM) and decreased after inhibition of phospholipase C (PLC) with U-73122. On blocking the receptors with specific neutralizing antibodies, changes in [Ca2+]i were abrogated. IL-8 also contracted the HASMC, decreasing the length of cells by 15%, and induced a 2.5-fold increase in migration. These results indicate that HASMC constitutively express functional CXCR1 and CXCR2 that mediate IL-8-triggered Ca2+ release, contraction, and migration. These data suggest a potential role for IL-8 in causing abnormal airway structure and function in asthma and CF.

Effect of areca on contraction of colonic muscle strips in rats

AIM: To investigate the effects of areca on the contractile activity of isolated colonic muscle strips in rats and mechanism involved.

METHODS: Each strip (LMPC, longitudinal muscle of proximal colon; CMPC, circular muscle of proximal colon; LMDC, longitudinal muscle of distal colon; CMDC, circular muscle of distal colon.) was suspended in a tissue chamber containing 5 mL Krebs solution (37 °C), bubbled continuously with 950 mL•L⁻¹ O₂ and 50 mL•L⁻¹ CO₂. The mean contractile amplitude (A), the resting tension (T), and the contractile frequency (F) were simultaneously recorded on recorders.

RESULTS: Areca dose dependently increased the mean contractile amplitude, the resting tension of proximal and distal colonic smooth muscle strips in rats (P < 0.05). It also partly increased the contractile frequency of colonic smooth muscle strips in rats (P < 0.05). The effects were partly inhibited by atropine (the resting tension of LMPC decreased from 0.44 ± 0.12 to 0.17 ± 0.03; the resting tension of LMDC decreased from 0.71 ± 0.14 to 0.03 ± 0.01; the mean contractile amplitude of LMPC increased from -45.8 ± 7.2 to -30.5 ± 2.9; the motility index of CMDC decreased from 86.6 ± 17.3 to 32.8 ± 9.3; P < 0.05 vs areca), but the effects were not inhibited by hexamethonium (P > 0.05).

CONCLUSION: Areca stimulated the motility of isolated colonic smooth muscle strips in rats. The stimulation of areca might be relevant with M receptor partly.