Effect of glucocorticoids on glycosaminoglycan metabolism in cultured human skin fibroblasts.

Human skin fibroblasts were exposed to 3 anti-inflammatory steroids in order to study their effects on the glycosaminoglycan metabolism. The potent glucocorticoids, fluocinolone acetonide and budesonide, even at low concentrations strongly reduced the accumulation of hyaluronic acid and sulfated glycosaminoglycans in the medium, at the cell surface, and in the cells. Hydrocortisone had considerably less effect. The 3 compartments were not influenced to the same extent and the least inhibition was noted in the cell surface pool. Dermatan sulfate was decreased to the same relative extent in all 3 compartments, while hyaluronic acid and heparan sulfate were specifically retained at the cell surface, explaining why this compartment was less affected than the others. Dermatan sulfate was studied in more detail regarding effects on its copolymeric structure. Glucocorticoid treatment changed the uronosyl composition of the polysaccharides so that a relative decrease of glucuronic acid residues and a relative increase of iduronic acid residues were noted. This change was most evident in dermatan sulfate of the medium and of the cell surface. Thus, glucocorticoid treatment not only reduces the quantity of various glycosaminoglycans but also changes the distribution, the relative proportion, and the structure of connective tissue proteoglycans. These effects probably contribute to the development of skin atrophy, which often is observed after long-term treatment with potent glucocorticoids.

Antioxidant activity of some diarylselenides in biological systems.

The selenoorganic compounds di(4-aminophenyl)selenide (10) and 4-nitro-4'-amino-diphenylselenide (36) were shown to inhibit lipid peroxidation in ADP/Fe2+/ascorbate-treated microsomes and tert-butylhydroperoxide-treated hepatocytes with IC50s of 3 and 10 microM, and 14 and 10 microM, respectively. In the former system, these inhibition constants compare favourably with those of Ebselen and classical antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). In the cell system, these selenium compounds were equipotent with BHA but more potent than Ebselen and its analogues. The diamino compound (10) was also an effective inhibitor of lipid peroxidation initiated by diquat redox cycling in hepatocytes, again being equipotent with BHA but more potent than Ebselen and its analogues, which actually stimulated lipid peroxidation in this test system. Manipulation of the amino functions of (10) and (36) by alkylation or acylation altered the antioxidant capacity. Optimal activity in this series was achieved by N-ethylation or N-isobutylation of (10). This produced antioxidants having IC50s below 1 microM in the microsome system, 3-13 microM in the tert-butylhydroperoxide system, and being 100% effective in the diquat model at 50 microM. On the other hand, acylation or alkylation of the amino groups with long chain acyl or alkyl groups reduced the efficacy of the structures below that of the parent diamine. As with other antioxidant compounds, several of the chalcogenides were relatively selective inhibitors of monocyte 5'-lipoxygenase-dependent secretion of LTB4 as compared to their effect on cyclooxygenase-dependent secretion of PGE2 (for example compound 42 had IC50s of 0.6 microM and 10 microM, respectively). No correlation was observed between the redox-properties of the chalcogenides and their respective abilities to inhibit these enzymes.

Distribution of cholesterol and triglycerides among lipoprotein fractions in fat-fed rabbits at different levels of serum cholesterol.

The serum lipoproteins of rabbits given semisynthetic cholesterol-free diets containing coconut oil or butter or a conventional rabbit chow supplemented with cholesterol, were studied by preparative ultracentrifugation and electrophoresis. (1) All three diets elevated the total cholesterol level but only the coconut oil diet markedly increased the triglyceride (TG) content in addition. All ultracentrifugation fractions showed elevated cholesterol/TG ratios, and this was especially evident for the cholesterol diet. In the hyperlipidemic rabbits cholesterol was therefore mainly transported in lipoproteins with a changed lipid composition. (2) The lipid levels of the "HDL" fraction were more or less unaffected by the lipid concentration in whole serum. In the total serum cholesterol ranges 150-500 (coconut oil diet) and 100-300 mg/100 ml (cholesterol diet), most cholesterol was transported as "LDL" cholesterol. This latter fraction reached maximum cholesterol concentrations of about 350 (coconut oil diet) and 400 mg/100 ml (cholesterol diet) at total cholesterol levels of approximately 600 and 1200 mg/100 ml serum, respectively. At still higher levels of total cholesterol, the whole increment was concentrated to the "VLDL" fraction. (3) With semisynthetic diets in the whole cholesterol range 250-400 mg/100 ml it was possible, with respect to cholesterol, to induce fairly similar concentrations and distributions to those seen in man, with about 60% transported as "LDL", 30% as "VLDL" and 10% as "HDL" cholesterol with the coconut oil diet and 65%, 20% and 15%, respectively, with the butter diet. Such experimental conditions seem to be suitable for testing the hypocholesterolemic action of drugs intended for human hyperlipidemia Type II. (4) Compared with earlier investigations on rabbits, the present distribution study suggests that the degree of aortic lipid infiltration in cholesterol-fed rabbits is better related to the levels of "LDL" than to "VLDL" cholesterol.

Actions of vitamins A and E and some nicotinic acid derivatives on plasma lipids and on lipid infiltration of aorta in cholesterol-fed rabbits.

Marked hypercholesterolemia and moderate lipid infiltration of the aorta were induced by feeding rabbits a diet containing 1% cholesterol + 3% corn oil for 70 days. In the liver the concentration and pool size of cholesterol increased and those of triglycerides (TG) decreased. On dietary addition of vitamin A and vitamin E (44 000 I.U. and 125 mg respectively, once daily for 5 days a week) the following changes were noted in comparison with the fat-fed rabbits not receiving extra addition of vitamins. There was a slight decrease of the levels of plasma cholesterol and an increase of those of plasma TG. The liver cholesterol concentration increased but, according to the concomitant reduction of the liver weight, there was no significant change in lever cholesterol or TG pools. In the aorta the vitamins markedly reduced the lipid infiltrated area as well as the cholesterol content. Both niceritrol** and S-2040 [pyridine-2,5-dicarboxylic acid di(beta-pyridylcarbinol ester)] in a dietary concentration of 0.5% decreased plasma cholesterol by about 20%. This reduction, as well as that induced by the vitamins, was confined to the VLDL-fractions only. S-2040 slightly reduced the cholesterol accumulation in the aorta. In rabbits given both the vitamins and niceritrol or S-2042 there was an additive reduction of plasma cholesterol. Here the nicotinic acid derivatives were partly able to counteract the increases of plasma TG induced by the vitamins. In the aorta the combination vitamins + S-2042 but not that of vitamins + niceritrol tended to give a better protection than the vitamins alone. On a normal diet vitamins A + E significantly increased the liver cholesterol concentration and pool and decreased the liver TG pool, but did not affect the other parameters. Possible mechanisms for the prophylactic action of the vitamins against lipid infiltration of the aorta of cholesterol-fed rabbits are discussed.

A nicotinic acid ester and experimental atherosclerosis: no significant effect of treatment with niceritrol (pentaerythritoltetranicotinate) on cholesterol in aorta of rabbits previously fed with cholesterol-enriched diet.

The influence of niceritrol on cholesterol in serum, liver and inner aorta of 115 rabbits was studied during a period where a cholesterol-enriched diet was given and during two succeeding periods after which cholesterol addition to the diet was discontinued. Niceritrol given together with cholesterol for 6 weeks reduced significantly the concentration of cholesterol in serum and liver, but not in the inner aorta. During 16 weeks decrease of serum cholesterol after discontinuation of cholesterol feeding no significant effect of niceritrol was observed on the decrease in serum and liver cholesterol or on the concentration of cholesterol in inner aorta. When serum cholesterol had normalized 16 weeks after discontinuation of cholesterol feeding, addition of niceritrol to the diet for the following 16 weeks did not significantly affect the concentration of cholesterol in liver and inner aorta. Animals in all groups were injected intravenously with an equal amount of [3H] cholesterol 3 weeks before discontinuing cholesterol feeding. Niceritrol did not significantly affect the amount of accumulated labelled cholesterol in inner aorta. The present results indicated that niceritrol had no significant effects on metabolism of cholesterol in inner aorta of the hypercholesterolemic and previously hypercholesterolemic rabbits.

Protective effects of the glucocorticoid, budesonide, on lung anaphylaxis in actively sensitized guinea-pigs: inhibition of IgE-but not of IgG-mediated anaphylaxis.

1 The effect of glucocorticoid pretreatment on antigen-induced bronchoconstriction was studied in guinea-pigs actively sensitized to two different ovalbumin regiments (one producing IgE- and IgG-like antibodies and the other exclusively IgG-like antibodies). 2 Budesonide (50 mg/kg) and hydrocortisone (50 mg/kg) given as one intraperitoneal injection 15-20 h before and anaphylactic tests or as two consecutive intraperitoneal injections 5 and 6 days before, led to a decreased bronchial capacity. In this respect glucocorticoid pretreatment was effective only in guinea-pigs sensitized to produce both IgE-like and IgG-like antibodies. 3 Budesonide pretreatment also reduced the capacity of anaphylactically-challenged chopped lung tissue to release histamine in guinea-pigs sensitized to produce both IgE- and IgG-like antibodies. 4 Budesonide pretreatment did not change the levels of circulating IgG1a and IgE-like homocytotropic antibodies as measured by passive cutaneous anaphylaxis; nor did it affect histamine or methacholine-induced bronchoconstriction in vivo or the capacity of histamine or methacholine to contract the guinea-pig isolated trachea preparation of the isoprenaline-induced relaxation of this preparation. 5 The selective inhibitory effects of budesonide and hydrocortisone on IgE-mediated but not IgG-mediated anaphylaxis and the relevance to human atopic disease are discussed.

Alpha-(phenylselenenyl)acetophenone derivatives with glutathione peroxidase-like activity. A comparison with ebselen.

Here we describe a new class of organoselenium compounds possessing glutathione peroxidase-like activity. The parent compound, alpha-(phenylselenenyl)acetophenone (PSAP), increased the rate of reaction of glutathione with H2O2, tert-butylhydroperoxide, cumene hydroperoxide, linoleic acid hydroperoxide and dilinoleyl lecithin hydroperoxide by 7.0, 25.1, 34.1, 19.1 and 8.4-fold, respectively, as assessed by the oxidized glutathione (GSSG) reductase enzyme assay. Direct assay of the removal of hydrogen peroxide and glutathione from reaction mixtures confirmed the peroxidase-like activities of these selenoorganic compounds, but indicate that the conventional coupled GSSG reductase assay may be unsuitable for the assessment of the catalytic capacity of PSAP and Ebselen. One possible mechanism of catalysis by PSAP involves an initial oxidation at selenium. Thiol may then react with the selenoxide to yield a selenium (II) compound, H2O and a disulfide. Compounds derived from PSAP may provide potential selenium-based anti-inflammatory agents.

Antioxidative properties of organotellurium compounds in cell systems.

The protective/antioxidative properties of diaryl tellurides were demonstrated in cellular systems of increasing complexity. In the presence of glutathione, bis(4-hydroxyphenyl) telluride (1a), bis(4-aminophenyl) telluride (1d) and bis(2-carboxyphenyl) telluride (1h) reduced by more than 50% t-butyl hydroperoxide-induced cell death in lung fibroblast cultures at concentrations below 2 microM. Bis(2,6-dimethyl-4-hydroxyphenyl) telluride (2b) reduced by more than 50% leukocyte-mediated and phorbol-12-myristate-13-acetate-stimulated damage to Caco-2 cells at 0.1 microM concentration. As judged by their abilities to reduce formation of thiobarbituric acid reactive substances at concentrations close to 1 microM, diaryl tellurides 1a, 1d and 2b protected rat kidney tissue against oxidative damage caused by anoxia and reoxygenation. The organotellurium compounds also offered protection after systemic administration. In the presence of diaryl telluride 2b (0.1-1 microM), the ischemia/reperfusion-induced vascular permeability increase in the hamster cheek pouch was significantly reduced as compared with the control. Some of the most active organotellurium cell protectants were evaluated for their ability to inhibit formation of the inflammatory mediators leukotriene B4 and interleukin-1beta. An inhibitory effect on the secretion of these species was seen for compounds 1a and 2b at or above 10 microM concentrations. The protective effects of diaryl tellurides against t-butyl hydroperoxide-induced cell injury can be ascribed mainly to the peroxide-decomposing, glutathione peroxidase-like capacity of the compounds. The chain-breaking, electron- or hydrogen atom-donating ability of diaryl tellurides seems to be the main reason for their protection against leukocyte-mediated cell damage in Caco-2 cells and in the oxidatively challenged rat kidney and hamster cheek pouch.

Cytokine modulation by glucocorticoids: mechanisms and actions in cellular studies.

Glucocorticoids inhibit the expression and action of most cytokines. This is part of the in vivo feed-back system between inflammation-derived cytokines and CNS-adrenal produced corticosteroids with the probable physiological relevance to balance parts of the host defence and anti-inflammatory systems of the body. Glucocorticoids modulate cytokine expression by a combination of genomic mechanisms. The activated glucocorticoid-receptor complex can (i) bind to and inactivate key proinflammatory transcription factors (e.g. AP-1, NF kappa B). This takes place at the promotor responsive elements of these factors, but has also been reported without the presence of DNA; (ii) via glucocorticoid responsive elements (GRE), upregulate the expression of cytokine inhibitory proteins, e.g. I kappa B, which inactivates the transcription factor NF kappa B and thereby the secondary expression of a series of cytokines; (iii) reduce the half-life time and utility of cytokine mRNAs. In studies with triggered human blood mononuclear cells in culture, glucocorticoids strongly diminish the production of the 'initial phase' cytokines IL-1 beta and TNF-alpha and the 'immunomodulatory' cytokines IL-2, IL-3, IL-4, IL-5, IL-10, IL-12 and IFN-gamma, as well as of IL-6, IL-8 and the growth factor GM-CSF. While steroid treatment broadly attenuates cytokine production, it cannot modulate it selectively, e.g. just the TH0, the TH1 or the TH2 pathways. The production of the 'anti-inflammatory' IL-10 is also inhibited. The exceptions of steroid down-regulatory activity on cytokine expression seem to affect 'repair phase' cytokines like TGF-beta and PDGF. These are even reported to be upregulated, which may explain the rather weak steroid dampening action on healing and fibrotic processes. Some growth factors, e.g. G-CSF and M-CSF, are only weakly affected. In addition to diminishing the production of a cytokine, steroids can also often inhibit its subsequent actions. Because cytokines work in cascades, this means that steroid treatment can block expression of the subsequent cytokines. The blocked cytokine activity does not depend on a reduced cytokine receptor expression; in fact available in vitro investigations show that while the cytokine expression is blunted, its receptor is upregulated. The cellular studies presented here may represent the maximum potential of steroids to modulate cytokine expression in human mononuclear cells. It remains to be determined by clinical-experimental studies how effective cytokine modulation can be achieved in situ in inflamed bowel by systemic or by topical steroid therapy. Such studies may also answer whether a blocked cytokine production/action is the key or just a secondary mechanism behind the unique efficacy of steroids in active inflammatory bowel disease.

Gut mucosal uptake and retention characteristics contribute to the high intestinal selectivity of budesonide compared with prednisolone in the rat.

BACKGROUND: Budesonide and prednisolone are both effective for the treatment of inflammatory bowel disease, but budesonide produces fewer adverse systemic effects. High first-pass hepatic inactivation of budesonide partially explains its favourable ratio between topical and systemic activity, but it is probable that its uptake and retention in intestinal target tissues are also contributory. AIM: To compare the uptake and retention of radio-labelled budesonide and prednisolone in rat ileal mucosa in vivo. METHODS: 3H-Budesonide and 3H-prednisolone were applied for 10 min directly to a perfused segment of rat ileum in vivo, followed by saline lavage every 10 min. Steroid uptake into the mucosa and submucosa was assessed at 20 min and 4 h. The uptake of budesonide was also measured in allergen-challenged animals vs. saline-challenged controls to assess whether inflammation of the mucosa with ongoing plasma exudation would impair its uptake. RESULTS: Budesonide was better absorbed into ileal tissue (15-fold at 20 min) than prednisolone and better retained (50-fold at 4 h) after topical administration. The uptake of budesonide was not impaired by exudation processes following allergen challenge. CONCLUSIONS: The higher uptake and retention characteristics of budesonide in gut mucosa should contribute to its greater intestinal selectivity compared with that of prednisolone.

Topical anticolitic efficacy and selectivity of the glucocorticoid budesonide in a new model of acetic acid-induced acute colitis in the rat.

AIMS: To study the effect of local or parenteral administration of the glucocorticoid budesonide in the acetic acid-induced colitis model in the rat. METHODS: Colitis was induced in an exteriorized colonic segment by administration of 4% acetic acid for 15 s. Four days later, this colonic segment with colitis was examined using a morphological scoring system, and measurements of myeloperoxidase activity and of plasma exudation into the colonic segment. The experimental colitis showed morphological similarities to human ulcerative colitis, with 3-fold increase in myeloperoxidase activity and 6-fold increase in the plasma exudation. Budesonide in different doses administered for 3 days, starting one day after acetic acid instillation, prevented the development of colitis in a dose-dependent manner. The best effect of budesonide on the morphological score was achieved after local treatment at a dose of 10(-5) M twice daily (76% reduction compared with a control colitis group) and parenteral treatment with 0.75 mg/kg (80% reduction). These doses also normalized myeloperoxidase activity and significantly reduced the plasma exudation. The systemic effects of the drug were most pronounced in the group treated with parenteral budesonide. This group showed the greatest reduction in body weight and a significant reduction of the weight of adrenal glands and spleen (as compared to controls). Thymus weight in animals treated systemically was significantly lower than in locally treated animals. In the group treated with local budesonide the weight of adrenals was reduced. However, the weights of spleen and thymus were not reduced and the reduction of the body weight was even less than in the control group. CONCLUSION: Local treatment with budesonide at a dose of 10(-5) M (0.17 mg/kg if completely absorbed, but only 0.03 mg/kg with 15% bioavailability on colonic application) was as effective as parenteral treatment at a dose of 0.75 mg/kg in the attenuation of acetic acid-induced colitis in the rat, but resulted in minor systemic side-effects.

Interleukin-2 and -4 induce resistance of granulocyte-macrophage colony-stimulating factor to corticosteroids.

In vitro pretreatment of human mononuclear blood cells with a combination of interleukin-2 and interleukin-4 decreases corticosteroid receptor affinity and reduces the anti-proliferative effects of corticosteroids. Similar abnormalities have been observed in mononuclear blood cells of steroid-resistant asthmatics. In vitro steroid resistance was induced by 48 h pretreatment of mononuclear blood cells from healthy individuals (n = 10) with interleukin-2 and interleukin-4 (500 Units (U)/ml). The effects of three structurally different corticosteroids (10(-7)-10(-11) M) on lipopolysaccharide-stimulated (10 ng/ml; 20 h) production of granulocyte-macrophage colony-stimulating factor (GM-CSF) were examined. GM-CSF production was efficiently inhibited by all three corticosteroids in the control cultures. Cortivazol was significantly more potent (IC50 = 3 x 10(-11) M) than budesonide and tipredane (IC50 = 2.5 x 10(-10) M and IC50 = 2 x 10(-10) M, respectively). However. interleukin-2 and interleukin-4 pretreatment counteracted the inhibitory effects of all three corticosteroids to a similar degree. The results highlight the importance of interleukin-2 and interleukin-4 in the induction of steroid resistance, since pretreatment of mononuclear blood cells with these cytokines impaired corticosteroid inhibition of GM-CSF production.

Diaryl tellurides as inhibitors of lipid peroxidation in biological and chemical systems.

Diaryl tellurides carrying electron-donating substituents in the para positions were found to efficiently inhibit peroxidation of rat hepatocytes, rat liver microsomes and a chlorobenzene solution of phosphatidylcholine. The most active compound in the microsomal assay, bis(4-dimethylaminophenyl) telluride, showed an IC50-value of 30 nM. This compound also caused a dose-dependent delay of the onset of the linear phase of microsomal peroxidation stimulated by iron/ADP/ascorbate. The peak oxidation potentials of the diaryl tellurides (0.50-1.14 V in MeCN) correlated linearly with the IC50-values in this assay, with a point of inflection around 0.85 V. In the hepatocyte system, all compounds showed similar protective activity. It is proposed that diaryl tellurides exert an antioxidative effect by deactivating both peroxides and peroxyl radicals under the formation of telluroxides. These oxides may regenerate the active divalent organotellurides upon exposure to a suitable reducing agent.

The effect of acute cigarette smoke inhalation on pulmonary and systemic cysteine and glutathione redox states in the rat.

Inhalation of Tobacco smoke (TS) by rats for 1 h caused significant depletions in the free glutathione (GSH) of homogenate supernatants of whole lung (13.9-8.8 mumol/g protein), lavage cells (2.7-1.7 nmol/10(6) cells) and lavage fluid (1.3-0.4 microM). In each case the depletions were nonrecoverable by dithiothreitol (DTT) suggesting conjugation between GSH and TS-borne electrophiles. Corresponding lung cysteine (CySH) components were unaffected by TS inhalation. In contrast, TS inhalation had no effect on the blood plasma GSH redox balance at various points around the circulation, but was shown to affect those of CySH, causing significant reductions in total CySH in plasma samples obtained both pre- and postpulmonarily. Similarly, the redox status of GSH in homogenate supernatants of whole liver was unaffected by TS inhalation, but there were significant increases in hepatic free CySH. These results indicate that acute TS inhalation increases the oxidant burden on the lungs causing a transient depletion of GSH in a variety of pools. Concurrently, the lungs may possess regulatory mechanism(s) which respond immediately by the uptake of CySH equivalents present in plasma disulfides.

Lung and systemic thiol homeostasis during an acute lung inflammation in the rat.

The instillation of Sephadex beads into the lungs of rats induces a sustained, acute inflammatory reaction within the lungs which caused significant increases in whole lung free and total glutathione (GSH) of approximately 30% after 72 h of reaction. Concurrently, levels of free and total cysteine (CySH) were increased by approximately 600% and 300%, respectively. Similarly, extended inflammation raised the intracellular content of free and total GSH in intraluminal cells by approximately 50% whilst causing the accumulation of oxidised CySH in the extracellular lavage fluid. Simultaneously, fluctuative trends were noted in several systemic thiol pools. Liver free and total GSH were shown to fall without alteration to CySH components. In contrast the plasma redox balance of GSH was unaltered but depletions of free and total CySH were noted after 72 h of inflammation. These results are discussed in terms of the occurrence of oxidative stress during acute pulmonary inflammation and the relationship of these observations to systemic thiol homeostasis and observations in other models of oxidant-induced pulmonary toxicity.

6 alpha-Fluoro- and 6 alpha,9 alpha-difluoro-11 beta,21-dihydroxy-16 alpha,17 alpha-propylmethylenedioxypregn-4-ene-3,20-dione: synthesis and evaluation of activity and kinetics of their C-22 epimers.

It is generally accepted that the anti-inflammatory effect of glucocorticosteroids cannot be separated from their adverse effects at the receptor level. However, modification of the pharmacokinetics through structural alterations could provide steroids with a better therapeutic index than those currently used. Thus, new 16 alpha,17 alpha-acetals between butyraldehyde and 6 alpha-fluoro- or 6 alpha,9 alpha-difluoro-16 alpha-hydroxycortisol were synthesized and studied. Acetalization of the corresponding 16 alpha,17 alpha-diols or transacetalization of their 16 alpha,17 alpha-acetonides in dioxane produced mixtures of C-22 epimers, which were resolved by preparative chromatography. Alternatively, an efficient method was used to produce the 22R-epimer stereoselectively through performing the acetalization and transacetalization in a hydrocarbon with an inert material present. The C-22 configuration of (22R)-6 alpha,9 alpha-difluoro-11 beta,21-dihydroxy-16 alpha,17 alpha-propylmethylenedioxypregn-4-ene-3,20-dione was unambiguously established by single crystal X-ray diffraction. The present compounds, especially the 22R-epimer just mentioned, bind to the rat thymus glucocorticoid receptor with high potency. The C-22 epimers of the 6 alpha,9 alpha-difluoro derivatives showed a 10-fold higher biotransformation rate than the budesonide 22R-epimer when incubated with human liver S9 subcellular fraction. The high receptor affinity in combination with the high biotransformation rate indicates that (22R)-6 alpha,9 alpha-difluoro-11 beta,21-dihydroxy-16 alpha,17 alpha-propylmethylenedioxypregn-4-ene-3,20-dione may be an improved 16 alpha,17 alpha-acetal glucocorticosteroid for therapy of inflammatory diseases, in which the mucous membranes are involved, such as those in the intestinal tract as well in the respiratory tract.

Seasonal variation in the function of blood monocytes obtained from healthy nonsmokers, asymptomatic smokers, and smokers with chronic bronchitis.

The present study focused on two questions: What effects do cigarette smoking and chronic bronchitis have on the function of the precursors of alveolar macrophages, the blood monocytes? Can seasonal variations affect the function of these cells? Phagocytic activity (the proportion of yeast-ingesting cells and the mean number of yeast particles per ingesting cell) and metabolism of arachidonic acid [secretion of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in zymosan-stimulated cultures] were studied as markers of monocyte function during three seasons: spring (May-June), autumn (November-December), and winter (February). Smokers with chronic bronchitis (SCBs) and asymptomatic smokers (ASs) had a lower proportion (p < 0.05) of ingesting monocytes than healthy nonsmokers (HNSs) during spring, but not during the other two seasons. The secretion of PGE2 was highest during autumn and lowest during spring in the monocytes of all three groups. In autumn, LTB4 secretion was increased in the monocytes of HNSs (p < 0.05) but not in those of ASs and SCBs. LTB4 secretion was similar in all groups during the other two seasons. Cigarette smoking and chronic bronchitis seem to impair the function of monocytes and may thereby affect the systemic host defense activity. Cells collected during autumn were generally more active than those sampled in spring, indicating marked seasonal variation in the function of monocytes from all three groups.

Prospects for future topical glucocorticoid development.

Current glucocorticoids are inactivated mainly in the liver. Results from studies of their catabolism; their concentration gradients in epidermis and upper and lower dermis after topical application to intact and injured skin; and the concentration needed to inhibit synthesis of human connective tissue by skin fibroblasts; suggest that their systemic and local adverse reactions would logically be reduced further by adding a rapid extrahepatic biotransformation. An ideal glucocorticoid should be locally inactivated during, or immediately after, absorption. The data available for three glucocorticoids with some extrahepatic metabolism suggest that such relatively labile steroids may have a more autoregulating absorption than that of the conventional, more stable, steroids. This means that in skin areas with a damaged stratum corneum, the balance between steroid influx and inactivation may favour anti-inflammatory activity, while that balance is insufficient in intact skin for a triggering of glucocorticosteroid activity. When the skin lesions heal, and the high influx rate tapers off, corticosteroid activity in the epidermis and dermis may be better cut off than with the conventional, metabolically stable, corticosteroids. The compounds subject to local metabolism available today appear to have only moderate topical corticosteroid activity. There are still no valid data to support a claim that their catabolic effects on the connective tissue of diseased skin are less than those of conventional topical steroids. However, novel glucocorticosteroids with a still better relation between high intrinsic glucocorticosteroid activity and rapid metabolic turnover in skin should be designed and tested.

Development of glucocorticosteroids with enhanced ratio between topical and systemic effects.

A high potency at the application site and a low incidence of glucocorticoid side-effects form the desired profile of glucocorticosteroids for anti-inflammatory therapy. A new type of glucocorticosteroid 16,17-acetals with an improved topical/systemic activity ratio has been developed. Non-symmetric 16,17-acetal substitution increased the topical anti-inflammatory activity more than the systemic activity in rodents, whereas fluorine substitution in 9 alpha- or 6 alpha,9 alpha-positions increased the systemic more than the topical potency. The non-fluorinated, non-symmetric 16 alpha,17 alpha-acetal budesonide reached the highest ratio, which was five to ten times better than that of the earlier known 16,17-acetonides such as triamcinolone acetonide, or that of the 17 alpha-esters such as beclomethasone 17 alpha,21-dipropionate. Although budesonide and betamethasone 17 alpha,21-diproprionate have the same topical anti-inflammatory potency, the latter decreased plasma and urinary cortisol levels significantly more when ointment preparations were compared in volunteers. Budesonide is efficiently biotransformed in the liver to metabolites such as 6 beta-hydroxybudesonide and 16 alpha-hydroxyprednisolone, which are 50-100 times less potent than the parent steroid. In homogenates of rat or human adult livers budesonide is biotransformed two to five times more rapidly than desonide and triamcinolone acetonide.