IL-15 promotes cytokine production of human T helper cells

IL-15 is a newly identified cytokine that has T cell and B cell growth factor activity similar to that of IL-2. In this study, a novel biologic function of IL-15 to promote cytokine production by human Th cells has been elucidated. Dermatophagoides farinae 11 (a major allergen of house dust mite)-specific human T cell clones produced IL-5 in response to recombinant human IL-15 as well as to either anti-CD3 or IL-2 stimulation. IL-5 mRNA became detectable 3 h after IL-15 stimulation and reached a maximum at 9 h. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T cell clones was clearly transcribed in response to IL-15, indicating that the approximately 500-bp human IL-5 promoter/enhancer segment 5' upstream of the coding region sufficiently responded to IL-15. IL-15-induced IL-5 synthesis was completely inhibited by the tyrosine kinase inhibitor, herbimycin A, suggesting the involvement of tyrosine kinases in the signal transduction leading to IL-5 synthesis as well as to proliferation of T cells induced by IL-15. Whereas IL-5 production by human peripheral T cells was abolished by the addition of anti-IL-2-neutralizing Abs into the culture, IL-15 restored the IL-5 synthesis despite effective IL-2 neutralization. IL-15 produced at the site of allergic inflammation may play a role in the recruitment and activation of eosinophils by inducing IL-5 (a Th2 cytokine) production by T cells.

A novel phosphodiesterase inhibitor, T-440: possible management of eosinophilic inflammation by down-regulation of interleukin-5 production

The effect of T-440, a selective type IV phosphodiesterase (PDE IV) inhibitor on interleukin (IL)-5 production by peripheral blood mononuclear cells (PBMCs) of atopic asthmatic subjects was investigated. PBMCs produced IL 5 following challenge with specific allergen in vitro. T-440 suppressed allergen-induced IL-5 production significantly at a concentration of 1 microgram/ml. T-440 inhibited cyclic AMP-phosphodiesterase (PDE) activity in a concentration dependent manner and raised the intracellular cyclic AMP level of PBMCs significantly. Dibutyryl cyclic AMP suppressed IL-5 production by PBMCs in a similar way to T-440, suggesting that the increase of intracellular cyclic AMP caused by T-440 reduces IL-5 production. T-440 may be an effective agent to treat atopic diseases associated with eosinophilic inflammation, e.g. asthma and atopic dermatitis.

Impairment of the gastric hyperemic response to luminal acid in cirrhotic rats

Liver cirrhosis impairs gastric mucosal resistance to luminal acid in humans and in animal models. Because we have previously shown that pentagastrin enhances defensive as well as aggressive factors implicated in mucosal injury, we examined the hypothesis that the pentagastrin-mediated enhancement of mucosal defense mechanisms may be impaired in cirrhotic rats. Increased acid backdiffusion and susceptibility to gross mucosal injury, associated with an elimination of the hyperemic response to gastric barrier disruption, was observed in cirrhotic rats. In in vivo microscopic studies in anesthetized rats, cirrhosis had no effect on pentagastrin-associated enhancement of mucus gel thickness or baseline gastric mucosal blood flow, although baseline mucus gel thickness was decreased. Cirrhosis did, however, abolish the luminal acid-related hyperemic response to pentagastrin, which was associated with impaired intracellular pH homeostasis during acid superfusion. Cirrhosis did not alter submucosal calcitonin gene-related peptide immunoreactive nerves. We conclude that acid backdiffusion and pentagastrin-associated hyperemic responses are important mucosal defensive factors that are specifically impaired by cirrhosis.

Barrier function of the gastric mucus gel

The gastric epithelium is covered by a continuous layer of secreted mucus and bicarbonate. The function of this mucobicarbonate layer in terms of protecting the epithelial cells from luminal acid is controversial. Several studies conducted in vitro have shown that gastric mucus can slow proton diffusion and can enable the formation of a pH gradient across the mucobicarbonate layer. In our laboratory, simultaneous measurements of intracellular pH and the thickness of the mucus gel overlying gastric surface cells in vivo indicated that surface cell acidification rates and mucus gel thickness were inversely related. This suggests that the gastric mucobicarbonate layer delays proton permeation into gastric surface cells, enabling secreted bicarbonate to neutralize luminal acid. Several theoretical models, including the effects of mucus and bicarbonate secretion, convection, stirring, and lipids are offered as a possible explanation for the experimental observations. Lipid content and additional unstirred layers outside of the mucus gel are offered as possible explanations for the experimental observations. On the basis of the available data and theoretical considerations, we can conclude that all of these factors probably interact in an integrated manner to protect the gastric epithelial cells from damage due to luminal acid.

Allergen-specific human T cell clones produce interleukin-5 upon stimulation with the Th1 cytokine interleukin-2

CD4+ T cell clones specific for Der fII (a major allergen of the house dust mite) were established from peripheral blood mononuclear cells of atopic patients. All of the T cell clones were classified as having the Th0 phenotype, since they produced both interleukin (IL)-2 and IL-4 upon stimulation. Some of the clones produced IL-5 upon antigenic stimulation. Human recombinant IL-2 induced these T cell clones to express IL-5 mRNA and produce IL-5 protein in a dose-dependent manner. IL-2 did not induce IL-4 production, indicating a discrete signal requirement for IL-4 versus IL-5 production by T cells. Moreover, IL-5 production induced by immobilized anti-CD3 monoclonal antibody was completely suppressed by the addition of anti-IL-2 monoclonal antibody, suggesting that IL-5 production, designated as a Th2-type immune response, is dependent on IL-2, a Thl cytokine. IL-2 produced at the site of allergic inflammation may contribute to IL-5 production by T cells in vivo.

IL-5 production by CD4+ T cells of asthmatic patients is suppressed by glucocorticoids and the immunosuppressants FK506 and cyclosporin A

IL-5 was produced in vitro by peripheral blood mononuclear cells (PBMC) of mite-sensitive atopic patients upon challenge with specific allergen, while PBMC of healthy controls produced essentially no IL-5. Stimuli delivered by the combination of phorbol ester and Ca2+ ionophore induced marked IL-5 production by PBMC obtained from atopic and non-atopic asthmatics, suggesting that both protein kinase C and Ca2+ influx are required for IL-5 production. CD2- or CD4-bearing cell depletion almost completely removed IL-5-producing cells while CD8-bearing cell depletion rather enriched them. These findings indicate that CD4+ T cells are the principal source of IL-5 in PBMC. The capacity of PBMC of atopic asthmatics, non-atopic asthmatics and healthy controls to produce IL-2, IL-4, IL-5 and IFN-gamma was compared, to find that cytokine-producing capacities other than that of IL-5 (IL-2, IL-4 and IFN-gamma) were not significantly different among the three groups. Dexamethasone, FK506 and cyclosporin A suppressed IL-5 production in vitro in a dose-dependent manner. Clear dose-dependent suppression of IL-5 gene expression by FK506 was also observed. Treatment of asthmatic patients with inhaled glucocorticoid (beclomethasone dipropionate) ameliorated clinical symptoms, improved lung function and markedly suppressed IL-5 production by PBMC, suggesting the essential role of IL-5 in the pathogenesis of bronchial asthma and the clinical importance of its regulation.

[Relationship between myocardial perfusion state immediately after reperfusion therapy and left ventricular wall motion improvement in patients with acute myocardial infarction]

The relationship between myocardial contrast echocardiography and improvement of the left ventricular wall motion was studied as an indicator of the prognosis of patients with acute myocardial infarction. Ten patients with acute anterior myocardial infarction who demonstrated successful reperfusion (improved to TIMI grade III) and patency of the responsible coronary artery during the chronic stage (one month after the onset) were selected. The contrast study used 2 ml of sonicated iopamidol injected into the left coronary artery. Two-dimensional echocardiograms were taken at the level of papillary muscle on the short axis for recording in VTR. The results of the contrast study were evaluated using a contrast defect score based on the degree and width of the contrast defect. Percent wall motion improvement was measured as an index of improvement of the left ventricular wall motion and CKmax was used for estimating the extent of myocardial necrosis. There was a good correlation between contrast defect score and CKmax (r = 0.853) or % wall motion improvement (r = 0.77). No correlation was found between coronary occlusion time and CKmax nor between coronary occlusion time and % wall motion improvement. The results suggest that if the score is high, recovery of left ventricular wall motion cannot be expected in patients with acute myocardial infarction who demonstrate successful reperfusion. In such cases, myocardial perfusion has not been effectively restored and myocardial necrosis extended over a wide area. If the score is low, recovery of the wall motion can be expected in the chronic stage even though abnormal left ventricular wall motion area is extensive immediately after reperfusion therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin E2 enhances gastric defense mechanisms against acid injury in uremic rats

BACKGROUND/AIMS

Uremia increases gastric mucosal H+ permeability and acid back-diffusion-related injury in rats. The aim of this study was to examine the effect of the synthetic gastroprotective compound 16,16-dimethyl prostaglandin E2 (16,16-dm PGE2) on the gastric barrier to acid injury in uremic rats.

METHODS

Chronic renal failure was induced by subtotal nephrectomy. Acid back-diffusion injury was induced by superfusion with 15% ethanol in 0.15N HCl and was assessed by image analysis. Intracellular pH, initial surface cell acidification rate, and thickness of mucous gel layer were measured with in vivo microscopy. Gastric mucosal blood flow was measured in separate experiments by laser-Doppler flowmetry.

RESULTS

Pretreatment with 16,16-dm PGE2 attenuated H+ back-diffusion and prevented the production of gross lesions. 16,16-dm PGE2 increased gastric mucous gel thickness, decreased initial acidification rate, and maintained intracellular pH homeostasis during exposure to luminal acid. Gastric mucosal blood flow was not changed during superfusion with a neutral buffer but increased during acid exposure in rats treated with 16,16-dm PGE2.

CONCLUSIONS

16,16-dm PGE2 attenuated H+ back-diffusion injury in uremic rats. This effect was associated with blunting of the initial decrease of intracellular pH and enhanced surface cell intracellular pH homeostasis during acid exposure. These effects were associated with an increased mucous gel layer thickness and an acid-related increase in blood flow.

Impairment of gastric mucosal defenses measured in vivo in cirrhotic rats

Patients with cirrhosis have an increased incidence of gastric ulcers and erosions. We evaluated the effect of carbon tetrachloride-induced cirrhosis on rat gastric mucosal defense mechanisms using our recently developed in vivo fluorescence microscopy technique. Cirrhotic rats had increased portal vein pressure, increased serum aminotransferase concentrations and decreased serum albumin concentrations. We noted significantly more spontaneous gross gastric lesions in the cirrhotic rats. In vivo microscopic measurements revealed that cirrhotic rats had (a) a significantly thinner gastric mucous gel layer, (b) a much greater decrease in surface mucosal cell intracellular pH in response to an acid load, (c) decreased gastric mucosal blood flow and (d) decreased surface cell viability. We conclude that spontaneous gastric mucosal lesions in cirrhotic rats may be related to more rapid penetration of acid through a thinner gastric mucous gel layer and a lower mucosal blood flow. These changes are associated with a decreased ability of the surface cells to maintain intracellular pH homeostasis, increased initial gastric surface cell acidification, decreased surface cell viability and a lower blood flow that probably is inadequate to remove the increased acid.

Pentagastrin enhances gastric mucosal defenses in vivo: luminal acid-dependent and independent effects

Stimulation of acid secretion is associated with enhanced resistance of the gastric mucosa to damage by luminal acid. We studied the mechanism by which gastric mucosal defenses are modulated in a system in which mucus gel thickness, intracellular pH (pHi), gastric mucosal blood flow, and acid secretion can be measured simultaneously in vivo, using a recently developed microfluorometric technique. Intravenous infusion of pentagastrin in a dose associated with maximal acid secretion increased mucus gel thickness, pHi, and mucosal blood flow during superfusion with a neutral solution. Subsequent superfusion with an acidic buffer (pH 1.7) further increased blood flow to nearly three times basal. During superfusion with luminal acid, pHi fell more slowly and recovered toward baseline more quickly in pentagastrin-infused rats than in controls. Pretreatment with the H2-receptor antagonist cimetidine abolished the increased blood flow associated with pentagastrin, impairing pHi homeostasis, although cimetidine increased mucus gel thickness in the absence of pentagastrin. We conclude that gastric defense mechanisms at the preendothelial and postepithelial levels are enhanced during acid secretion as part of a histamine-dependent homeostatic mechanism that balances gastric protective mechanisms with acid secretion. The net result of these enhanced defenses is the preservation of gastric surface cell pHi despite the presence of a large proton gradient between lumen and blood.

Regulation of interleukin-5 production by peripheral blood mononuclear cells from atopic patients with FK506, cyclosporin A and glucocorticoid

Upon stimulation with phorbol ester and ionomycin, peripheral blood mononuclear cells (PBMC) of atopic patients with moderate eosinophilia produced significantly higher amounts of IL-5 compared to that of normal subjects. This finding renders further support to the notion that T cell-eosinophilic inflammation plays a central role in allergic disorders. IL-5 induction in vitro was completely inhibited by immunosuppressant FK506, cyclosporin A and dexamethasone. FK506 applied in vivo effectively suppressed clinical symptoms of atopic dermatitis and IL-5 production of PBMC. FK506 and cyclosporin A may become a better therapeutic modality against allergic diseases.

Isoproterenol enhances rat gastric mucosal barrier function in vivo

BACKGROUND

The mechanism by which topical isoproterenol protects the gastric mucosa from ethanol-induced injury is unclear; previous studies suggest that enhancement of mucosal blood flow may be contributory. Therefore, we investigated the role of isoproterenol pretreatment on rat gastric mucous gel layer thickness, mucosal blood flow, and surface cell intracellular pH.

METHODS

A portion of the gastric corpus of an anesthetized rat was isolated in a superfused chamber. Intracellular pH was measured with the fluorescent dye 5(6)-carboxyfluorescein diacetate, mucous gel thickness was measured by quantifying the distance between the focal planes of the epithelial cell and the gel surfaces, and mucosal blood flow was measured in separate experiments with a laser-Doppler flowmeter.

RESULTS

Pretreatment with topical isoproterenol markedly increased gastric mucous gel layer thickness, decreased surface cell initial acidification rates, and significantly enhanced the recovery of intracellular pH toward baseline values. Gastric mucosal blood flow was significantly higher in the isoproterenol-treated group compared with untreated controls, initially increasing, decreasing, and then increasing a second time during superfusion with acidic solutions.

CONCLUSIONS

Isoproterenol preserves gastric surface cell intracellular pH during acid superfusion. This effect may be a result of an increased thickness of the mucous layer, which delays proton entry into the surface cell, and an increase in mucosal blood flow in response to luminal acid, which appears to enhance recovery from intracellular acidosis.

[The effects of exogenous and endogenous dopamine on the gastric microcirculation and their action sites in rat stomach]

The effect of exogenous and endogenous dopamine on the gastric microcirculation and their action sites on stomach were investigated by laser Doppler flowmetry, histochemistry, electron microscopy and radioautography. The effects of graded doses of dopamine on the gastric mucosal blood flow were different from those on the systemic blood flow, implying that there may exist a dopaminergic control of gastric mucosal blood flow independent from the systemic circulation. By histochemical observations of the horseradish peroxidase (HRP) infused preparations, HRP was found to be distributed mainly to the arterioles and venules at the base of the gastric mucosa with a high dose of dopamine which may contributed to open the arterio-venular shunt either at the base of mucosa or in the submucosa. Pretreatment with monoamine oxidase inhibitor and/or 6-hydroxydopamine caused changes in the levels of endogenous catecholamine (dopamine, noradrenaline and adrenaline) in the stomach wall. An imbalanced catecholamine in the stomach wall, particularly an increase in DA, decreased gastric mucosal blood flow. Radioautographic studies revealed that D1-receptors are located mainly on the arterioles in the lower part of the mucosa and submucosa, while D2-receptors are located mainly on the muscularis mucosae and on the collecting venules. Tyrosine hydroxylase (TH) positive nerve fibers possibly corresponding to the dopaminergic fiber were evident in the vicinity to the arterioles, venules, and muscularis mucosae. Some TH-positive fibers were extended to the true capillaries in the mucosa. Dopamine beta-hydroxylase positive fibers were noted near the arterioles and venules both in the submucosa and the lower portion of mucosal layer. Based on the above results, the dopaminergic mechanisms are considered to be involved in the regulation of the gastric mucosal microcirculation through the dopaminergic nerves.

Effect of orogastric nicotine on rat gastric mucosal gel thickness, surface cell viability and intracellular pH

Intracellular pH was measured in vivo using a fluorescent, microscopic technique in gastric surface cells of rats exposed to orogastric nicotine on an acute or chronic basis. Mucosae were superfused with solutions of pH 3 or pH 1.7 in order to examine the rate of intracellular acidification and recovery. In rats acutely exposed to nicotine, the response of intracellular pH to superfusion with acidic solutions was blunted with respect to control rats in a dose-dependent manner. In contrast, intracellular pH of rats chronically treated with nicotine had an exaggerated response with respect to control rats, with more rapid acidification and diminished ability to maintain intracellular pH in the physiologic range. Mucus gel thickness was increased after acute nicotine exposure in a dose-dependent manner, whereas a dose-dependent decrease in thickness was seen after chronic nicotine exposure. Cell viability using the fluorescent vital dye propidium iodide was increased in rats acutely treated with orogastric nicotine; conversely, viability was decreased in chronically treated rats. We conclude that acute nicotine exposure diminishes, whereas chronic nicotine exposure enhances, the effect of luminal acidity on mucosal surface cell intracellular pH and cell viability. These divergent effects correlate inversely with mucus gel thickness, suggesting that the mucus gel layer is an important component of the gastric mucosal barrier.

[A study on normal coronary arteriogram by provocation and spontaneous anginal attack: 4 cases of ST elevated angina with normal coronary arteries by provoked and spontaneous attacks]

During 3 years and 5 months, we experienced 3 of 172 cases of provocations on normal coronary arteries which presented ST elevated angina by ergonovine provocations. The incidence was 2.5% and 4% for all ergonovine provocations and intracoronary ergonovine provocations respectively. One case presented spontaneous attack in coronary arteriography, indicating similar state to occur not only with provocation but also in spontaneous attack. Examination of literature revealed no apparent report on such cases as this. For pathogenesis, the possibility of changes of small vessels was suggested in view of various literature and its specificity to the coronary arterial region.

Uremia increases gastric mucosal permeability and acid back-diffusion injury in the rat

The possibility that chronic uremia renders the gastric mucosa more susceptible to acid injury was investigated. A rat model of chronic renal failure was induced by subtotal nephrectomy. [H+] back-diffusion across the mucosa, following intragastric perfusion of 0.15N HCl or 15% ethanol in 0.15N HCl, was significantly greater in uremic than in sham-operated rats. Gastric mucous gel thickness and transmural potential difference were significantly lower in rats with renal insufficiency. Furthermore, a significantly greater acidification rate of the surface epithelial cells was found in uremic rats than in sham-operated rats during superfusion with pH 1.7 buffer. Intragastric administration of acidified ethanol or aspirin solutions markedly increased gastric mucosal blood flow (68% and 89% respectively) in the sham-operated group producing mild injury, in contrast to uremic rats, where a lesser increase in mucosal blood flow (7% and 14% respectively) was associated with more pronounced mucosal injury. It was concluded that enhanced susceptibility to acid injury in uremia is due to a reduction of function of pre-epithelial, epithelial, and postepithelial elements of the gastric mucosal barrier.

Cushing's syndrome due to primary pigmented nodular adrenocortical disease with cardiac myxomas and mucocutaneous lentigines

A young Japanese female demonstrated unusual features of Cushing's syndrome, cardiac myxomas and mucocutaneous lentigines. At the age of 12 years she presented with growth failure and obesity. The dexamethasone suppression test, the metyrapone test and low corticotropin concentrations indicated a primary adrenal disorder. At surgery, the adrenal glands were not enlarged (the right, 4.0 g; the left; 4.5 g) but had numerous small dark brown nodules. The pathological findings showed multiple small black cortical nodules containing large cells with eosinophilic cytoplasm and lipofuscin, and internodular cortical atrophy. These abnormalities were consistent with primary pigmented nodular adrenocortical disease. At age 22 years she complained of fatigue and palpitations associated with mid-chest pain. Four cardiac myxomas, suspected from the echocardiogram, were surgically removed. Because Cushing's syndrome and cardiac myxomas are life-threatening conditions, an awareness of the complex is important.

Roles of muscularis mucosae and myofibroblasts in the healing process of acetic acid-induced ulcer

The changes in the localization of FITC-phalloidin-positive smooth muscle cells and interstitial cells were studied in control and acetic acid-treated rat fundic mucosa. In the control rats, the FITC-phalloidin-positive cells mostly corresponded to the smooth muscle cells of the muscularis mucosae, and the arteriolar and venular smooth muscle cells. On the other hand, 1 week after the acetic acid treatment, the fluorescence of the smooth muscle cells of the muscularis mucosae disappeared and a large number of fluorescent interstitial cells, probably corresponding to myofibroblasts, appeared in the regenerated mucosal layer. Three weeks after the application, severely thickened fluorescent muscularis mucosae were formed and the fluorescence of the interstitial cells was rather decreased.

Fluorescent histochemical study on the localization of myofibroblasts in the healing of acetic acid-induced gastric ulcers in the rat

The changes in the localization of FITC-phalloidin-positive smooth muscle cells and interstitial cells were studied in control and acetic acid-treated rat fundic mucosae. In the control rats, the FITC-phalloidin-positive cells mostly corresponded to smooth muscle cells of the muscularis mucosae, and arteriolar and venular smooth muscle cells. On the other hand, the fluorescence of the smooth muscle cells of the muscularis mucosae disappeared and a large number of fluorescent interstitial cells appeared in the regenerated mucosal layer in rats one week after the acetic acid-treatment, while three weeks after the application, severely thickened fluorescent muscularis mucosae were formed.

Involvement of autonomic nervous system in gastric mucosal defense mechanism

This article describes the histochemical, immunohistochemical, radioautographic, and ultrastructural localizations of aminergic and peptidergic nerves, neurotransmitter receptors, and their binding sites in the stomach wall. Cholinergic and vasoactive intestinal polypeptide (VIP)-ergic nerve fibers are distributed along the gastric microvasculature, within the myenteric and submucosal plexuses, and in the muscularis mucosae and circular muscle layer. In the mucosa, both nerve fibers evenly extend along the capillaries in association with the epithelial cells up to the mucosal surface. In particular, cholinergic nerves are proved to doubly innervate the mucosal capillaries and nonmuscular venules as well as the parietal cells. Adrenergic and neuropeptide Y (NPY)-containing nerves are distributed primarily along the arterioles of the gastric microvasculature, within the myenteric plexuses, and in the circular muscle layer. These nerve fibers extend up to the basal portion of the mucosa in close association with small arterioles, capillaries, and epithelial cells. Some of the adrenergic nerve axons are coexistent with the cholinergic nerve axons within the Schwann cell. Histamine H1 receptors are widely located on the walls of arterioles, capillaries and venules, while H2 receptors are evident not only on the parietal cells but also on the walls of the collecting venules and surrounding capillaries in the mucosa. Dopamine D1 receptors are predominantly located on the smooth muscle cells of the arterioles near the muscularis mucosae, while D2 receptors are present on the walls of postcapillary venules and collecting venules. Functional coordination of both intramural peptidergic nerves as intrinsic origin and aminergic nerves as extrinsic origin is considered to be essential for maintaining the gastric mucosal defense mechanism against a variety of aggressive factors.