Chitosan microspheres as a potential carrier for drugs

Chitosan is a biodegradable natural polymer with great potential for pharmaceutical applications due to its biocompatibility, high charge density, non-toxicity and mucoadhesion. It has been shown that it not only improves the dissolution of poorly soluble drugs but also exerts a significant effect on fat metabolism in the body. Gel formation can be obtained by interactions of chitosans with low molecular counterions such as polyphosphates, sulphates and crosslinking with glutaraldehyde. This gelling property of chitosan allows a wide range of applications such as coating of pharmaceuticals and food products, gel entrapment of biochemicals, plant embryo, whole cells, microorganism and algae. This review is an insight into the exploitation of the various properties of chitosan to microencapsulate drugs. Various techniques used for preparing chitosan microspheres and evaluation of these microspheres have also been reviewed. This review also includes the factors that affect the entrapment efficiency and release kinetics of drugs from chitosan microspheres.

Wound-healing risk factors after open reduction and internal fixation of calcaneal fractures

This retrospective study investigated outcomes of wound healing in a series of 63 consecutive patients with 64 fractures of the calcaneus who underwent open reduction and internal fixation done by two surgeons experienced in this fracture during a 3-year period. Thirty-nine patients were managed preoperatively as outpatient referrals before surgery. Twenty-four patients were admitted directly to the trauma service and were managed as inpatients preoperatively. Minimum patient follow-up was 6 months, with an average follow-up of 18 months. A trend correlating the time between injury and operative intervention with the incidence of complications in wounds was noted; the incidence rose in patients who underwent surgery >5 days after their injury. Two-layered closures had a lower incidence of dehiscence compared to single-layered tension-relieving sutures. Patients with a higher body-mass index (BMI) (kg/ m2) took longer to heal their wounds. Strong trends were noted to link BMI and severity of fractures. In the outpatient group, a history of active smoking preoperatively correlated with increased time to wound healing. In 43 patients, there were no wound-healing complications. In 21 feet, there were varying degrees of wound dehiscence. Average wound healing took 47 days. Risk factors for complications in the wound after calcaneal open reduction and internal fixation include single layered closure, high BMI, extended time between injury and surgery, and smoking. Age, type of immobilization, medical illness (including diabetes), type of bone graft, or use of a Hemovac did not influence wound healing.

Curcumin (Diferuloylmethane) inhibition of tumor necrosis factor (TNF)-mediated adhesion of monocytes to endothelial cells by suppression of cell surface expression of adhesion molecules and of nuclear factor-kappaB activation

Recruitment of leukocytes by endothelial cells and their subsequent migration from the vasculature into the tissue play major roles in inflammation. In the present study, we investigated the effect of curcumin, an antiinflammatory agent, on the adhesion of monocytes to human umbilical vein endothelial cells (EC). Treatment of EC with tumor necrosis factor (TNF) for 6 hr augmented the adhesion of monocytes to EC, and this adhesion was due to increased expression of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule-1 (ELAM-1). Pretreatment of EC for 1 hr with curcumin completely blocked their adhesion to monocytes, as well as the cell surface expression of ICAM-1, VCAM-1, and ELAM-1 in EC. Although curcumin inhibited adhesion even when administered 1 hr after TNF treatment, maximum inhibition occurred when added either 1 hr before or at the same time as TNF. As the induction of various adhesion molecules by TNF requires activation of the transcription factor NF-kappaB, the effect of curcumin on the activation of this factor in the EC was also investigated. A 30-min treatment with TNF activated NF-kappaB; the activation was inhibited in a concentration-dependent manner by pretreatment with curcumin, indicating that NF-kappaB inhibition may play a role in the suppression of expression of adhesion molecules in EC. Our results demonstrate that the antiinflammatory properties of curcumin may be attributable, in part, to inhibition of leukocyte recruitment.

Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) inhibits TNF-induced NF-kappaB activation, IkappaB degradation, and expression of cell surface adhesion proteins in human vascular endothelial cells

Most inflammatory agents activate nuclear transcription factor-kappaB (NF-kappaB) which results in expression of genes for cytokines, adhesion molecules, and enzymes involved in amplification and perpetuation of inflammation. Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) is an active component from the roots of Polygonum cuspidatum that has been reported to exhibit antiinflammatory properties but the mechanism is not known. In the present study we investigated the effects of emodin on the activation of NF-kappaB in human umbelical vein endothelial cells (EC). Treatment of EC with TNF activated NF-kappaB; preincubation with emodin inhibited this activation in a dose- and time-dependent manner. Emodin did not chemically modify NF-kappaB subunits but rather inhibited degradation of IkappaB, an inhibitory subunit of NF-kappaB. Since the promoter regions of ICAM-1, VCAM-1, and ELAM-1 contain NF-kappaB binding sites and these adhesion molecules are involved in the attachment of leukocytes to EC, the effect of emodin on the adhesion of monocytes to EC and the expression of these adhesion molecules was also studied. Treatment of EC with TNF for 6 h increased the adhesion of monocytes to EC, which correlated with increases in cell surface expression of ICAM-1, VCAM-1 and ELAM-1. Pretreatment of EC for 1 h with emodin inhibited both monocyte-EC attachment and expression of ICAM-1, ELAM-1 and VCAM-1. These results indicate that emodin is a potent inhibitor of NF-kappaB activation and expression of adhesion molecules and thus could be useful in treating various inflammatory diseases.

The oral Janus kinase/spleen tyrosine kinase inhibitor ASN002 demonstrates efficacy and improves associated systemic inflammation in patients with moderate-to-severe atopic dermatitis: results from a randomized double-blind placebo-controlled study

BACKGROUND

ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.

OBJECTIVES

The objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate-to-severe AD. Methods A total of 36 patients with moderate-to-severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28-day period (20 mg, 40 mg and 80 mg once daily).

RESULTS

ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg -1·3 ± 2·1, P = 0·81; 40 mg -3·1 ± 2·7, P = 0·27; 80 mg -4·7 ± 2·1, P = 0·01; placebo -1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose-dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis-associated biomarker E selectin/SELE.

CONCLUSIONS

In patients with moderate-to-severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.

Fracture risk in men with congestive heart failure risk reduction with spironolactone

OBJECTIVES

The purpose of this study was to determine whether spironolactone use is associated with fractures in men with congestive heart failure (CHF).

BACKGROUND

In rats with aldosteronism, spironolactone preserves skeletal strength. However, in humans, the relationship of spironolactone to fractures is not known.

METHODS

The medical records of all male patients with CHF from 1999 to 2005 treated at the Veterans Affairs Medical Center, Memphis, Tennessee, were reviewed (n = 4,735). Odds ratios with 95% confidence intervals of having a fracture associated with spironolactone use were estimated using conditional logistic regression.

RESULTS

We identified 167 cases with a single-incident fracture and matched these by age and race to 668 control subjects without fractures. After adjustment for covariates, spironolactone use was inversely associated with total fracture (odds ratio: 0.575; 95% confidence interval: 0.346 to 0.955, p = 0.0324).

CONCLUSIONS

The use of spironolactone is inversely associated with fractures in men with CHF.

Detection of caspase activation in situ by fluorochrome-labeled caspase inhibitors

Apoptosis is dependent on the activation of a group of proteolytic enzymes called caspases. Caspase activation can be detected by immunoblotting using caspase-specific antibodies or by caspase activity measurement employing pro-fluorescent substrates that become fluorescent upon cleavage by the caspase. Most of these methods require the preparation of cell extracts and, therefore, are not suitable for the detection of active caspases within the living cell. Using FAM-VAD-FMK, we have developed a simple and sensitive assay for the detection of caspase activity in living cells. FAM-VAD-FMK is a carboxyfluorescein (FAM) derivative of benzyloxycarbonyl-valine-alanine-aspartic acid-fluoromethyl ketone (zVAD-FMK), which is a potent broad-spectrum inhibitor of caspases. FAM-VAD-FMK enters the cell and irreversibly binds to activated caspases. Cells containing bound FAM-VAD-FMK can be analyzed by flow cytometry, fluorescence microscopy, or a fluorescence plate reader. Using FAM-VAD-FMK, we have measured caspase activation in live non-adherent and adherent cells. We show that FAM-VAD-FMK labeled Jurkat and HeLa cells that had undergone apoptosis following treatment with camptothecin or staurosporine. Non-stimulated negative control cells were not stained. Pretreatment with the general caspase inhibitor zVAD-FMK blocked caspase-specific staining in induced Jurkat and HeLa cells. Pretreatment of staurosporine-induced Jurkat cells with FAM-VAD-FMK inhibited affinity labeling of caspase-3, -6, and -7, blocked caspase-specific cell staining, and led to the inhibition of apoptosis. In contrast, the fluorescent control inhibitor FAM-FA-FMK had no effect. Measurement of caspase activation in 96-well plates showed a 3- to 5-fold increase in FAM-fluorescence in staurosporine-treated cells compared to control cells. In summary, we show that FAM-VAD-FMK is a versatile and specific tool for detecting activated caspases in living cells.

Magnetic resonance imaging of the uterus after endometrial resection

OBJECTIVE

Despite the increasing popularity of endometrial resection for the treatment of menstrual problems, the long term sequelae of this procedure are poorly recognised. As diagnostic hysteroscopy following endometrial resection is frequently unrewarding and transvaginal ultrasound is incapable of detecting subtle changes in endometrial morphology, magnetic resonance imaging was employed to evaluate the uterus.

DESIGN

Retrospective study of unselected post-operative women.

METHODS

Fifty-nine women, of whom 22 were amenorrhoeic, were studied a mean number of 34 months after endometrial resection, using a 1.5 Tesla magnetic resonance imaging system with a pelvic phased array coil for signal reception. T2-weighted FSE images were acquired through the long and short uterine axis and volumetric assessment of each uterine layer performed using an ISG Allegro workstation.

MAIN OUTCOME MEASURES

The location and volume of residual endometrium, the volume of junctional zone and myometrial tissue, and the presence of additional intrauterine and pelvic pathology were recorded.

RESULTS

Residual endometrium was demonstrated in all except three amenorrhoeic women, with a similar mean volume present in menstruating and amenorrhoeic groups. Additional findings included adenomyosis, haematometra, fallopian tube dilatation and free intraperitoneal fluid.

CONCLUSIONS

The majority of amenorrhoeic and all menstruating women have residual endometrium after endometrial resection. The lack of communication of islands of residual endometrium with the uterine cavity results in haematometra formation, fallopian tube dilatation and possibly free intraperitoneal fluid.

Immunomodulatory effects of neem (Azadirachta indica) oil

Immunomodulatory effects of neem oil were studied in mice. The animals were treated intraperitoneally (i.p.) with neem oil; control animals received the emulsifying agent with or without peanut oil. Peritoneal lavage, collected on subsequent days, showed a maximum number of leukocytic cells on day 3 following treatment with neem oil; peritoneal macrophages exhibited enhanced phagocytic activity and expression of MHC class-II antigens. Neem oil treatment also induced the production of gamma interferon. Spleen cells of neem oil-treated animals showed a significantly higher lymphocyte proliferative response to in vitro challenge with Con A or tetanus toxoid (TT) than that of the controls. Pre-treatment with neem oil, however, did not augment the anti-TT antibody response. The results of this study indicate that neem oil acts as a non-specific immunostimulant and that it selectively activates the cell-mediated immune (CMI) mechanisms to elicit an enhanced response to subsequent mitogenic or antigenic challenge.

Mast cells trigger epithelial barrier dysfunction, bacterial translocation and postoperative ileus in a mouse model

BACKGROUND

Abdominal surgery involving bowel manipulation commonly results in inflammation of the bowel wall, which leads to impaired intestinal motility and postoperative ileus (POI). Mast cells have shown to play a key role in the pathogenesis of POI in mouse models and human studies. We studied whether mast cells contribute to the pathogenesis of POI by eliciting intestinal barrier dysfunction.

METHODS

C57BL/6 mice, and two mast cell-deficient mutant mice Kit(W/W-v) , and Kit(W-sh/W-sh) underwent laparotomy (L) or manipulation of the small bowel (IM). Postoperative inflammatory infiltrates and cytokine production were assessed. Epithelial barrier function was determined in Ussing chambers, by measuring transport of luminal particles to the vena mesenterica, and by assessing bacterial translocation.

KEY RESULTS

In WT mice, IM resulted in pro-inflammatory cytokine and chemokine production, and neutrophil extravasation to the manipulated bowel wall. This response to IM was reduced in mast cell-deficient mice. IM caused epithelial barrier dysfunction in WT mice, but not in the two mast cell-deficient strains. IM resulted in a decrease in mean arterial pressure in both WT and mast cell-deficient mice, indicating that impaired barrier function was not explained by tissue hypoperfusion, but involved mast cell mediators.

CONCLUSIONS & INFERENCES

Mast cell activation during abdominal surgery causes epithelial barrier dysfunction and inflammation of the muscularis externa of the bowel. The impairment of the epithelial barrier likely contributes to the pathogenesis of POI. Our data further underscore that mast cells are bona fide cellular targets to ameliorate POI.

Zinc-naproxen complex: synthesis, physicochemical and biological evaluation

Naproxen has a propensity to cause ulcers whereas zinc ions are known to possess an anti-ulcer and anti-inflammatory activity. Therefore, zinc complex of naproxen was prepared by adding zinc sulfate to an aqueous solution of sodium naproxen and its structure was characterized by IR, 1H NMR and 13C NMR, UV, DSC, atomic absorption spectroscopy, and elemental analysis. Anti-inflammatory studies, using the carrageenan-induced hind paw oedema showed that there was a significant difference (P<0.05, ANOVA plotted by Dunnet's test) in the anti-inflammatory activity of naproxen, its zinc complex, and the physical mixture of naproxen and zinc sulfate. In addition, zinc complex of naproxen showed a significant reduction in ulcers (lesion index (LI)) as compared to that of naproxen and physical mixture of naproxen and zinc sulfate. Thus, the use of the complex may be preferable to naproxen alone.

Human immunodeficiency virus-1-tat induces matrix metalloproteinase-9 in monocytes through protein tyrosine phosphatase-mediated activation of nuclear transcription factor NF-kappaB

We have previously shown that human immunodeficiency virus (HIV)-1-tat induces the production of matrix metalloproteinase-9 (MMP-9) in human monocytes by a mechanism that is not understood. In the present report, we demonstrate that HIV-tat-induced expression of MMP-9 is blocked by inhibitors of protein tyrosine phosphatases (PTPases). PTPase inhibitors also blocked HIV-tat-induced nuclear transcription factor NF-kappaB activation and IkappaBalpha degradation required for MMP-9 induction. These results suggest that HIV-tat induces MMP-9 in human monocytes through activation of PTPase and NF-kappaB.

Induction of endothelial cell surface adhesion molecules by tumor necrosis factor is blocked by protein tyrosine phosphatase inhibitors: role of the nuclear transcription factor NF-kappa B

Recent studies from our laboratory have indicated that protein tyrosine phosphatase (PTPase) inhibitors can down-modulate the tumor necrosis factor (TNF)-mediated activation of the nuclear transcription factor NF-kappa B in ML-1a, a monocytic cell line (Singh and Aggarwal, J. Biol. Chem. 1995: 270: 10631). Since TNF is one of the major inducers of various adhesion molecules in human endothelial cells and their expression is known to require the activation of NF-kappa B, we examined the effect of PTPase inhibitors on the TNF-mediated induction of intracellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and endothelial leukocyte adhesion molecule (ELAM)-1. Like ML-1a, human dermal microvessel endothelial cells (MVEC) treated with TNF rapidly activated (within 30 min) NF-kappa B; this effect was completely abolished by co-treatment with phenylarsine oxide (PAO), a specific inhibitor of PTPase. The induction of ICAM-1, VCAM-1, and ELAM-1 by TNF in MVEC occurred within 6 h and was also completely down-regulated by PAO in a dose-dependent manner. PAO was found to be effective even when added 3 h after TNF, suggesting a rapid mode of action of this inhibitor. Besides PAO, other inhibitors of PTPase, including pervanadate and diamide, also blocked TNF-dependent NF-kappa B activation and induction of all the three adhesion proteins. Consistent with these results, the attachment of monocytes to MVEC was also blocked by the PTPase inhibitors. Thus, overall, our results demonstrate that a PTPase is involved either directly or indirectly in the pathway leading to the induction of endothelial cell adhesion molecules by TNF. Because of their role in cell adhesion, PTPase may provide a novel target of drug development for treatment of inflammation, atherogenesis, and tumor metastasis.

Use of RAPD and AFLP markers to identify inter- and intraspecific hybrids of Mentha

Three controlled crosses were carried out involving Mentha arvensis and Mentha spicata [M. spicata CIMAP/C30 x M. spicata CIMAP/C33 (cv. Neera); M. arvensis CIMAP/C18 x CIMAP/C17 (cv. Kalka); and M. arvensis CIMAP/C17 x M. spicata CIMAP/C33]. The parents were subjected to random amplified polymorphic DNA (RAPD) analysis with 80 primers, and polymorphic primers were tested for detecting coinherited RAPD profiles among the progeny of these crosses. Of 50 seedlings tested from each intraspecific cross, all demonstrated dominant profiles with the selected RAPD primers except the detected hybrid from respective crosses. Coinherited markers could be detected with the primers OPJ 01, MAP 06, OPT 08, and OPO 20 for M. arvensis; OPJ 05, OPJ 14, OPO 19, and OPT 09 for M. spicata; and OPJ 07, OPJ 10, OPJ 11, OPJ 14, and OPO 02 for the cross M. arvensis x M. spicata. In our amplified fragment length polymorphism (AFLP) analysis, 40 coinherited marker fragments were identified for the cross involving M. arvensis, 32 for the cross involving M. spicata, and 41 for the interspecific cross between M. arvensis and M. spicata. In all crosses, similarity values between the parents were less than those between the parents and the hybrids. Although RAPD markers are generally considered dominant, it is possible to identify a few codominant markers that behave like restriction fragment length polymorphism (RFLP) markers. This molecular marker system may be helpful in rapidly screening out hybrids in crops where cross-pollination is a problem.

Birth weights of infants of first generation Asian women in Britain compared with second generation Asian women

OBJECTIVES

To compare birth weights of infants of first generation Asian women (women born in the Indian subcontinent) with those of infants of second generation Asian women (born in the United Kingdom).

DESIGN

Retrospective case note study.

SETTING

Bolton District General Hospital.

SUBJECTS

331 Asian women who gave birth between January 1989 and December 1989: 220 of these women were first generation Asians and 111 were second generation Asians.

MAIN OUTCOME MEASURE

Birth weights of babies born to first and second generation Asian women.

RESULTS

At all gestational ages at delivery, babies born to second generation Asian women were heavier than those born to first generation women. The mean birth weight for babies of second generation women was 3196 g, 249 g more than the mean birth weight of 2946 g of babies of first generation women (P < 0.001). After a stepwise multiple regression analysis was carried out the adjusted difference in birth weights was 280 g, greater than the crude difference.

CONCLUSION

Birth weights are important in relation to perinatal mortality, which is notoriously high among Asians. The results of this study indicate that there is hope for lowering of perinatal mortality and improving postnatal growth in babies of second generation Asians.

Ethidium bromide stimulated hyper laccase production from bird's nest fungus Cyathus bulleri

AIMS

Effect of ethidium bromide, a DNA intercalating agent, on laccase production from Cyathus bulleri was studied.

METHODS AND RESULTS

The bird's nest fungus, Cyathus bulleri was grown on 2% (w/v) malt extract agar (MEA) supplemented with 1.5 microg ml(-1) of the phenanthridine dye ethidium bromide (EtBr) for 7 d and when grown subsequently in malt extract broth (MEB), produced a 4.2-fold increase in laccase production as compared to the untreated fungus. The fungal cultures following a single EtBr treatment, when regrown on MEA devoid of EtBr, produced a sixfold increase in laccase in MEB. However, on subsequent culturing on MEA in the absence of EtBr, only a 2.5-fold increase in laccase production could be maintained. In another attempt, the initial EtBr-treated cultures, when subjected to a second EtBr treatment (1.5 microg ml(-1)) on MEA for 7 d, produced a 1.4-fold increase in laccase production in MEB.

CONCLUSIONS

The white-rot fungus Cyathus bulleri, when treated with EtBr at a concentration of 1.5 microg ml(-1) and regrown on MEA devoid of EtBr, produced a sixfold increase in laccase production in MEB.

SIGNIFICANCE AND THE IMPACT OF THE STUDY

The variable form of C. bulleri capable of hyper laccase production can improve the economic feasibility of environmentally benign processes involving use of fungal laccases in cosmetics (including hair dyes), food and beverages, clinical diagnostics, pulp and paper industry, industrial effluent treatment, animal biotechnology and biotransformations.

Interferon-gamma-induced downregulation of CD4 inhibits the entry of human immunodeficiency virus type-1 in primary monocytes

We have previously shown that the treatment of monocytes with interferon-gamma (IFN-gamma) prior to exposure with human immunodeficiency virus type-1 (HIV) results in complete inhibition of HIV infection of monocytes. In the present report, we have extended this study to obtain information on the mechanism(s) underlying IFN-gamma-induced inhibition of HIV infection of monocytes. To examine the effect of IFN-gamma on HIV entry, the first event in the infectious cycle of the virus, we amplified HIV-gag sequences in the genomic DNA and RNA of IFN-gamma treated monocytes, and found no evidence for the presence of either proviral DNA or HIV RNA sequences. These results were consistent with the absence of intracellular HIV particles either in the latent or actively replicating state as determined by flow-cytometric analysis of these cells. Furthermore, no HIV-induced cytopathic effects, such as multinucleated giant cell formation or cell death, were observed in IFN-gamma-treated monocytes after their exposure to HIV. Stimulation of IFN-gamma-treated monocytes 6 days postinfection with tumor necrosis factor-alpha (TNF-alpha), which is known to augment HIV replication in the infected cells, did not result in the induction of the HIV indicating the absence of latent HIV infection in IFN-gamma-treated monocytes. Treatment of monocytes with IFN-gamma, TNF-alpha, or with a combination of the two agents which is known to induce antimicrobial free radical nitric oxide (NO2- in the murine system did not induce NO2- production human monocytes suggesting the antiviral activity of IFN-gamma to be independent of NO2(-)-mediated killing of HIV or HIV-infected monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased expression of alpha 4 beta 1 and alpha 5 beta 1 integrins on HTLV-I-infected lymphocytes

T cells interact with the extracellular matrix via integrin receptors and these interactions affect both cellular localization and proliferation. The importance of these interactions in retrovirus-induced diseases, however, remains less clear. In the present study, we investigated changes in T cell adhesion to extracellular matrix proteins by HTLV-I expressing cell lines and human peripheral blood lymphocytes infected with HTLV-I by cocultivation. Cell lines and acutely infected primary peripheral blood lymphocytes demonstrated enhanced adhesion to fibronectin. Acute infection of peripheral blood lymphocytes increased the expression of alpha 5 beta 1 and alpha 4 beta 1 integrins. Antibodies to the alpha 4, alpha 5, and beta 1 subunits inhibited attachment of infected cells to fibronectin. We conclude that HTLV-I infection is associated with an increase in the expression of both the classical fibronectin receptor and the receptor for the alternatively spliced domain of fibronectin on peripheral blood lymphocytes. HTLV-I-related alterations in cell surface adhesion molecules may contribute to the abnormal proliferation of T cells in adult T cell leukemia (ATL) or to the abnormal localization of activated or infected T cells to the central nervous system of patients with tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM).

Cholinergic receptor activation on epithelia protects against cytokine-induced barrier dysfunction

AIM

Various types of cholinergic receptors are expressed on intestinal epithelia. Their function is not completely understood. We hypothesize that cholinergic receptor activation on epithelium may serve a protective function in cytokine-induced barrier dysfunction.

METHODS

The effect of cholinergic receptor activation on cellular barrier function in epithelial cells was assessed by measuring electrical impedance, and by determining para-cellular transport in transwell experiments. Cell lysates treated with cytokine and/or cholinergic agonists were analysed for cyto- and chemokine production, and tight junction (TJ) protein rearrangement was assessed. Primary colonic epithelial cells were isolated from surgically resected colon tissue of patients with inflammatory bowel disease.

RESULTS

IL-1β induced production of chemokines (CXCL-1, CXCL-10, IL-8, CCL-7) and led to a rearrangement of TJ proteins (occludin and ZO-1). This response was inhibited by pre-treatment with muscarinic, rather than nicotinic, acetylcholine receptor agonists. Treatment with IL-1β enhanced paracellular permeability (4kD dextran) and reduced impedance across the monolayer, which was counteracted by pre-incubation with acetylcholine, or muscarinic receptor agonist bethanechol. The protective effect of acetylcholine was antagonized by atropine, underscoring muscarinic receptor involvement. IL-1β induced transcription of myosin light chain kinase and phosphorylation of myosin light chain, and this cytokine-induced phosphorylation of MLC was inhibited by muscarinic receptor agonists. Furthermore, in epithelial cells from resection material of patients with Crohn's disease and ulcerative colitis, high expression of CXCL-8 was associated with a reduced choline acetyl transferase expression, suggesting an aberrant epithelial production of ACh in inflammatory context.

CONCLUSION

Acetylcholine acts on muscarinic receptors on epithelial cells to maintain epithelial barrier function under inflammatory conditions.