Recombinant human lactoferrin ingestion attenuates indomethacin-induced enteropathy in vivo in healthy volunteers

OBJECTIVE

To determine whether recombinant human lactoferrin ingestion inhibits nonsteroidal antiinflammatory drugs (NSAID)-induced gastroenteropathy in vivo in healthy volunteers as a model for disorders associated with a rise in permeability of the stomach and the small intestine.

DESIGN

A randomized crossover dietary intervention.

SUBJECTS AND INTERVENTIONS

In all, 15 healthy volunteers (age 23+/-1.4 y) were tested. A sucrose and a lactulose/rhamnose (L/R) permeability test was performed to assess gastroduodenal and small intestine permeability as indicator of NSAID-induced gastroenteropathy. All subjects consumed standardized meals for 2 days. On the second day at time=-24 h each subject ingested a drink containing 5 g recombinant human lactoferrin or placebo during breakfast. At t=-9 h, subjects ingested the same drink with 75 mg of the NSAID indomethacin and after an overnight fast at t=-1 h subjects consumed the drink and 50 mg indomethacin. After 1 h, at t=0, a permeability test was performed.

RESULTS

Small intestine permeability after indomethacin and placebo was significantly higher (L/R ratio=0.036; 0.014-0.092, P<0.05) compared to the permeability observed after ingestion of indomethacin and lactoferrin (0.028; 0.015-0.056), whereas gastroduodenal permeability did not differ between the two interventions (P=0.3).

CONCLUSION

Oral recombinant human lactoferrin supplementation during a short-term indomethacin challenge reduced the NSAID-mediated increase in small intestinal permeability and hence may provide a nutritional tool in the treatment of hyperpermeability-associated disorders.

SPONSORSHIP

Grant and human recombinant lactoferrin donated from Agennix Inc., Houston, TX.

Adaptive cytoprotection induced by pretreatment with ethanol protects against gastric cell damage by NSAIDs

In this study, we examined adaptive cytoprotection against NSAIDs in human gastric carcinoma cells in culture. Pretreatment of cells with low (nontoxic) concentrations of ethanol protected cells from cell death induced by subsequent exposure to NSAIDs. The adaptive cytoprotection against NSAIDs induced by ethanol was not attenuated by pretreatment of cells with inhibitors of protein synthesis or prostaglandin synthesis, thus inferring that neither newly synthesized proteins nor prostaglandins are involved in this process. Furthermore, treatment of cells with the low concentration of ethanol did not affect the synthesis and secretion of mucin. In in vivo experiments on rats, oral preadministration of a low dose of ethanol protected the gastric mucosa from gastric lesions induced by subsequent oral administration of NSAIDs. One possible explanation for this in vivo phenomenon is that the adaptive cytoprotection induced by ethanol protects the gastric mucosa from the direct cytotoxic effect of NSAIDs.

Enalapril Interferes with the Effect of Diclofenac on Leucocyte-Endothelium Interaction in Hypertensive Rats

Nonsteroidal anti-inflammatory drugs are known to attenuate the effects of some antihypertensive agents. However, the effect these drugs have on leukocyte migration when combined with antihypertensive agents has not been studied. To investigate this effect, we treated spontaneously hypertensive rats with saline, diclofenac, enalapril, or diclofenac combined with enalapril and observed leukocyte-endothelium interaction. Blood pressure was increased by diclofenac, reduced by enalapril and reduced by the combination of the two. Diclofenac did not interfere with the blood pressure-lowering effect of enalapril. Internal spermatic fascia venules were observed using intravital microscopy. Diclofenac reduced rollers, whereas enalapril, alone or combined with diclofenac, had no significant effect on rollers. All treatments reduced adherent and migrated leukocytes and expression of endothelial intercellular adhesion molecule-1. Venular shear rate, venular diameters, number of circulating leukocytes, and post-leukotriene B4 expression of l-selectin and CD11/CD18 integrin in leukocytes were unaffected by any treatment. Expression of P-selectin was reduced by diclofenac and unaffected by enalapril, even when combined with diclofenac. Our data suggest that, although diclofenac does not interfere with the enalapril anti-hypertensive effect, enalapril interferes with the effect diclofenac has on leukocyte rolling and endothelial P-selectin expression. Involvement of reduced endothelial intercellular adhesion molecule-1 expression might explain the lower numbers of adherent and migrated leukocytes. The anti-inflammatory properties of a nonsteroidal anti-inflammatory drug could therefore be attenuated in hypertensive patients receiving an angiotensin-converting enzyme inhibitor.

Polyamines reverse non-steroidal anti-inflammatory drug-induced toxicity in human colorectal cancer cells

Naproxen, sulindac and salicylate, three NSAIDs (non-steroidal anti-inflammatory drugs), were cytotoxic to human colorectal cancer cells in culture. Toxicity was accompanied by significant depletion of intracellular polyamine content. Inhibition of ornithine decarboxylase (the first enzyme of the polyamine biosynthetic pathway), induction of polyamine oxidase and spermidine/spermine N(1)-acetyltransferase (the enzymes responsible for polyamine catabolism) and induction of polyamine export all contributed to the decreased intracellular polyamine content. Morphological examination of the cells showed typical signs of apoptosis, and this was confirmed by DNA fragmentation and measurement of caspase-3-like activity. Re-addition of spermidine to the cells partially prevented apoptosis and recovered the cell number. Thus polyamines appear to be an integral part of the signalling pathway mediating NSAID toxicity in human colorectal cancer cells, and may therefore also be important in cancer chemoprevention in humans.

Anti-inflammatory activity and gastric lesions induced by zinc-tenoxicam

Oral administration of tenoxicam or zinc-tenoxicam complex inhibited to a similar extent carrageenin-induced paw oedema and granulomatous tissue formation in rats as well as the acetic acid induced writhing response in mice. Gastric lesions induced by oral administration of zinc-tenoxicam were reduced in number and severity when compared with those induced by tenoxicam or the co-administration of tenoxicam and zinc acetate. However, after intraperitoneal administration, both zinc-tenoxicam and tenoxicam plus zinc acetate induced a reduced number of gastric lesions as compared with tenoxicam.

IL-1-driven endogenous IL-10 production protects against the systemic and local acute inflammatory response following intestinal reperfusion injury

TNF-alpha release and action are central in the pathogenesis of the local and systemic inflammatory responses that occur after intestinal reperfusion. In this study we examined whether IL-1 participated in the cascade of events leading to TNF-alpha production and TNF-alpha-mediated injury following reperfusion of the ischemic superior mesenteric artery in rats. Blockade of the action of IL-1 by the use of anti-IL-1 antiserum or administration of IL-1R antagonist (IL-1ra), a natural antagonist of IL-1Rs, resulted in marked enhancement of reperfusion-associated tissue injury, TNF-alpha expression, and lethality. In contrast, there was marked decrease in IL-10 production. Facilitation of IL-1 action by administration of anti-IL-1ra, which antagonizes endogenous IL-1ra, or exogenous administration of rIL-1beta suppressed reperfusion-induced tissue pathology, TNF-alpha production, and lethality, but increased IL-10 production. Exogenous administration of IL-10 was effective in preventing the increase in tissue or plasma levels of TNF-alpha, the exacerbated tissue injury, and lethality. An opposite effect was observed after treatment with anti-IL-10, demonstrating a role for endogenous production of IL-10 in modulating exacerbated reperfusion-associated tissue pathology and lethality. Finally, pretreatment with anti-IL-10 reversed the protective effect of IL-1beta on reperfusion-associated lethality. Thus, IL-1 plays a major role in driving endogenous IL-10 production and protects against the TNF-alpha-dependent systemic and local acute inflammatory response following intestinal reperfusion injury.

Activation of STAT3 by IL-6 and IL-10 in primary human macrophages is differentially modulated by suppressor of cytokine signaling 3

On human macrophages IL-10 acts as a more potent anti-inflammatory cytokine than IL-6, although both cytokines signal mainly via activation of the transcription factor STAT3. In this study we compare IL-10 and IL-6 signaling in primary human macrophages derived from blood monocytes. Pretreatment of macrophages with PMA or the proinflammatory mediators LPS and TNF-alpha blocks IL-6-induced STAT3 activation, whereas IL-10-induced activation of STAT3 remains largely unaffected. Although LPS induces the feedback inhibitor suppressor of cytokine signaling 3 (SOCS3) in macrophages, inhibition of IL-6 signal transduction by LPS occurs rapidly and does not depend on gene transcription. We also found that pretreatment of macrophages with IL-10 inhibits subsequent STAT3 activation by IL-6, whereas IL-10-induced STAT3 activation is not affected by preincubation with IL-6. This cross-inhibition is dependent on active transcription and might therefore be explained by different sensitivities of IL-10 and IL-6 signaling toward the feedback inhibitor SOCS3, which is induced by both cytokines. In contrast to the IL-6 signal transducer gp130, which has been previously shown to recruit SOCS3 to one of its phosphotyrosine residues (Y759), peptide precipitation experiments suggest that SOCS3 does not interact with phosphorylated tyrosine motifs of the IL-10R. Taken together, different sensitivities of IL-10 and IL-6 signaling toward mechanisms that inhibit the Janus kinase/STAT pathway define an important mechanism that contributes to the different anti-inflammatory potencies of these two cytokines.

Cu/Zn superoxide dismutase plays important role in immune response

Activation of macrophages leads to the secretion of cytokines and enzymes that shape the inflammatory response and increase metabolic processes. This, in turn, results in increased production of reactive oxygen species. The role of Cu/Zn superoxide dismutase (SOD-1), an important enzyme in cellular oxygen metabolism, was examined in activated peritoneal elicited macrophages (PEM) and in several inflammatory processes in vivo. LPS and TNF-alpha induced SOD-1 in PEM. SOD-1 induction by LPS was mainly via extracellular signal-regulated kinase-1 activation. Transgenic mice overexpressing SOD-1 demonstrated a significant increase in the release of TNF-alpha and of the metalloproteinases MMP-2 and MMP-9 from PEM. Disulfiram (DSF), an inhibitor of SOD-1, strongly inhibited the release of TNF-alpha, vascular endothelial growth factor, and MMP-2 and MMP-9 from cultured activated PEM. These effects were prevented by addition of antioxidants, further indicating involvement of reactive oxygen species. In vivo, transgenic mice overexpressing SOD-1 demonstrated a 4-fold increase in serum TNF-alpha levels and 2-fold stronger delayed-type hypersensitivity reaction as compared with control nontransgenic mice. Conversely, oral administration of DSF lowered TNF-alpha serum level by 4-fold, lowered the delayed-type hypersensitivity response in a dose-dependent manner, and significantly inhibited adjuvant arthritis in Lewis rats. The data suggest an important role for SOD-1 in inflammation, establish DSF as a potential inhibitor of inflammation, and raise the possibility that regulation of SOD-1 activity may be important in the treatment of immune-dependent pathologies.

Atropine reverses the antinociception of nonsteroidal anti-inflammatory drugs in the tail-flick test of mice

The nonsteroidal anti-inflammatory drugs (NSAIDs) clonixin, diclofenac, piroxicam, ketoprofen, meloxicam, and paracetamol induced antinociception after intraperitoneal or intrathecal administration in mice submitted to an acute thermal algesiometric test without inflammation (tail-flick). Antinociception was evaluated by the increase in reaction time difference (Delta latency), between readings obtained before and after the administration of drugs. The antinociception induced by doses of NSAIDs producing between 20% and 30% of the maximum possible effect (MPE) 30 min after intraperitoneal and 15 min after intrathecal injections was compared with the antinociception obtained after pretreatment with 1 mg/kg atropine ip, 30 min before. Systemic atropine (1 mg/kg) significantly antagonized NSAID-induced antinociception in all cases, both after intraperitoneal and intrathecal administration. Cholinergic depletion by intracerebroventricular hemicholinium-3 (HC-3, 5 microg) 5 h before prevented the antinociceptive effect of all NSAIDs. These observations suggest that intrinsic muscarinic cholinergic facilitatory pathways represent an important modulating system in pain perception in this animal model of acute thermal pain. The results of the present work support the increasingly accepted notion that NSAIDs are effective analgesics even when inflammation is not present, acting by mechanisms that involve actions on spinal and supraspinal nociceptive transmission. It is suggested that, similar to morphine and clonidine, the active mechanism of NSAIDs may involve the release of acetylcholine (ACh) in the spinal cord.

Neuroprotection of cultured cortical neurons mediated by the cyclooxygenase-2 inhibitor APHS can be reversed by a prostanoid

The neuroprotective properties of two cyclooxygenase-2 (COX-2) specific inhibitors, N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS398) and o-(acetoxy-phenyl)hept-2-ynyl2 sulfide (APHS) were examined in vitro using a mixed cortical neuronal culture system. Each of these inhibitors conferred a concentration-dependent neuroprotective effect against an excitotoxic assault induced by NMDA. Neuroprotection was observed when the COX-2 inhibitor was added before or even 1-3 hours after NMDA, which was coincident with an NMDA-induced increase of COX-2 transcripts in neurons. To test whether these COX-2 inhibitors confer neuroprotection by inhibiting biosynthesis of prostanoids that may contribute toward excitotoxicity, two NMDA-induced prostanoids, PGE(2) and PGF(2alpha), were tested for their ability to reverse the neuroprotective properties of APHS. APHS-mediated neuroprotection was overcome by the concentration-dependent (as low as 100 nM) administration of a synthetic analog of PGE2, 17-phenyl-trinor-PGE(2) (17-pt-E(2)), which is a relatively specific agonist for the EP1 and EP3 prostaglandin receptors; however, PGF(2alpha) had no significant effect on neuroprotection conferred by APHS. In the absence of APHS, neuroprotection was observed with either prostanoid. PGE(2) may in some instances contribute toward excitotoxicity, and the inhibition of synthesis of this prostanoid may in part explain the neuroprotective properties of these COX-2 inhibitors.

Decrease in efficacy and potency of nonsteroidal anti-inflammatory drugs by chronic delta(9)-tetrahydrocannabinol administration

Cannabinoids have been shown to increase the release of arachadonic acid, whereas nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to decrease the analgesic effects of cannabinoids. We evaluated the antinociceptive effects of chronic administration of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), anandamide (an endogenous cannabinoid), arachadonic acid, ethanolamine, and methanandamide on several NSAIDs via p.o. and/or i.p. routes of administration using the mouse p-phenylquinone (PPQ) test, a test for visceral nociception. Our studies with a cannabinoid receptor (CB1) antagonist [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride (SR141716A)], a CB2 antagonist [N-((1S)-endo-1,3,3-trimethyl-bicyclo-heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide) (SR144528)], and an another CB2 agonist [1,1-dimethylbutyl-1-deoxy-Delta(9)-THC (JWH-133)] were performed to better characterize PPQ interactions with cannabinoid receptors. The acute affects of Delta(9)-THC were blocked by SR141716A (i.p.) and partially blocked by SR144528 (i.p.). When NSAIDs (p.o.) were administered, the ED(50) values were as follows: 23 mg/kg aspirin, 3 mg/kg indomethacin, 5 mg/kg celecoxib, 3 mg/kg ketorolac, 57 mg/kg acetaminophen (32.3-99.8), and 0.8 mg/kg diclofenac (0.1-4.9). In animals given chronic Delta(9)-THC, only diclofenac and acetaminophen were active. Conversely, chronic methanandamide (i.p.) did not alter the antinociceptive effects of the NSAIDs. Neither the CB1 or CB2 antagonist blocked the effects of the NSAIDs. The effects of chronic arachadonic acid, ethanolamine, and anandamide could not be evaluated. In summary, our data indicate that chronic Delta(9)-THC alters the cyclooxygenase system. Alternatively, the data suggest that this alteration is not due to chronic endogenous cannabinoid release. Based upon these data, we hypothesize that human subjects who are chronic users of Delta(9)-THC may not respond to analgesic treatment with the above NSAIDs.

Involvement of ATP-sensitive K(+) channels in the peripheral antinociceptive effect induced by dipyrone

We evaluated the effect of several K(+) channel blockers on the peripheral antinociception induced by dipyrone using the rat paw pressure test, in which sensitivity is increased by intraplantar injection (2 micro g) of prostaglandin E(2). Dipyrone administered locally into the right hindpaw (50, 100 and 200 micro g) elicited a dose-dependent antinociceptive effect which was demonstrated to be local, since only higher doses produced an effect when injected in the contralateral paw. The specific blockers of ATP-sensitive K(+) channels glibenclamide (40, 80 and 160 micro g/paw) and tolbutamide (80, 160 and 320 micro g/paw) antagonized the peripheral antinociception induced by dipyrone (200 micro g/paw). Charybdotoxin (2 micro g/ paw), a blocker of large conductance Ca(2+)-activated K(+) channels, and dequalinium (50 micro g/paw), a selective blocker of small conductance Ca(2+)-activated K(+) channels, did not modify the effect of dipyrone. This effect was also unaffected neither by intraplantar administration of non-specific voltage-dependent K(+) channel blockers tetraethylammonium (1700 micro g) and 4-aminopyridine (100 micro g) nor cesium (500 micro g), a non-specific K(+) channel blocker. These results suggest that the peripheral antinociceptive effect of dipyrone may result from activation of ATP-sensitive K(+) channels, while other K(+) channels appear not to be involved in the process.

2, 4-diamino-6- hydroxy pyrimidine inhibits NSAIDs induced nitrosyl-complex EPR signals and ulcer in rat jejunum

BACKGROUND

It has been suggested that one aspect of non-steroidal anti-inflammatory drugs induced intestinal damage is due to either uncoupling of mitochondrial oxidative phosphorylation or inhibition of electron transport. We investigated the latter possibility using electron paramagnetic resonance spectroscopy.

RESULTS

Electron paramagnetic studies of NSAIDS on sub-mitochondrial particles revealed that indomethacin, but not with nabumetone, bound to a site near to Complex I and ubiquinone to generate a radical species. Normal rats exhibited prominent [3Fe-4S]ox signals (g approximately 2.01) at 20 K. One hour after indomethacin there was a prominent, intense and broad absorption pattern at (g approximately 2.07) suggesting, appearance of radical species overlapping [3Fe-4S]ox and was unaffected by pretreatment with 2,4 diamino -6-hydroxy pyrimidine. At 24 hrs, when macroscopic ulcers were seen, there was a new signal due to a nitric oxide radical (NO*). In contrast, nabumetone and 2,4 diamino-6-hydroxy pyrimidine pre-treated animals receiving indomethacin exhibited electron paramagnetic resonance spectra identical to those of controls at 24 hrs and neither was associated with small intestinal ulcers. Indomethacin and 2,4 diamino hydroxy pyrimidine pre-treated rats, but not nabumetone, had increased intestinal permeability.

CONCLUSION

The results suggest that the in vivo effects of indomethacin modulate the mitochondrial respiratory chain directly at 1 h and 24 h through formation of nitric oxide. NO* appears to play an important role in the late pathogenic stages of NSAID enteropathy and may be the site for targeted treatment to reduce their toxicity.

Prostaglandin E(2) protects intestinal tumors from nonsteroidal anti-inflammatory drug-induced regression in Apc(Min/+) mice

Nonsteroidal anti-inflammatory drugs (NSAIDs) are antitumorigenic in humans as well as in animal models of intestinal neoplasia, such as the adenomatous polyposis coli (Min/+) (Apc(Min/+)) mouse. NSAIDs inhibit cyclooxygenase (COX) isozymes, which are responsible for the committed step in prostaglandin biosynthesis, and this has been considered the primary mechanism by which NSAIDs exert their antitumorigenic effects. However, mounting evidence suggests the existence of COX-independent mechanisms. In the present study, we attempted to clarify this issue by treating Apc(Min/+) mice bearing established tumors with NSAIDs (piroxicam and sulindac, 0.5 and 0.6 mg/mouse/day, respectively) for 6 days and concomitantly bypassing COX inhibition by treatment with the E prostaglandin (EP) receptor agonists 16,16-dimethyl-prostaglandin E(2) (PGE(2)) and 17-phenyl-trinor-PGE(2) (10 microg each, three times daily) administered via gavage and/or i.p. routes. Treatment with piroxicam and sulindac resulted in 95% and 52% fewer tumors, respectively, and a higher ratio of apoptosis:mitosis in tumors from sulindac-treated mice as compared with controls. These effects were attenuated by concomitant EP receptor agonist treatment, suggesting PGE(2) is important in the maintenance of tumor integrity. Immunological sequestration of PGE(2) with an anti-PGE(2) monoclonal antibody likewise resulted in 33% fewer tumors in Apc(Min/+) mice relative to untreated controls, additionally substantiating a role for PGE(2) in tumorigenesis. The EP receptor subtype EP1 mediates the effects of PGE(2) by increasing intracellular calcium levels ([Ca(2+)](i)), whereas antagonism of EP1 has been shown to attenuate tumorigenesis in Apc(Min/+) mice. We demonstrate that [Ca(2+)](i) is significantly elevated in tumors of Apc(Min/+) mice relative to the adjacent normal-appearing mucosa. Furthermore, treatment with piroxicam results in significantly lower [Ca(2+)](i) in tumors, and this effect is attenuated by concomitant treatment with the EP1/EP3 receptor agonist 17-phenyl-trinor-PGE(2). Overall, our results suggest that NSAIDs exert their antitumorigenic effects, in part, via interference with PGE(2) biosynthesis, and these effects may be mediated through changes in intracellular calcium levels.

Enantioselective inhibition of the binding of rac-profens to human serum albumin induced by lithocholate

The reversible binding of lithocholate to human serum albumin determines a decrease of the binding of rac-ketoprofen. The process was followed by displacement chromatography using increasing concentrations of the competitor, i.e., lithocholate, in the mobile phase. The inhibition of rac-ketoprofen binding resulting was enantioselective and greater displacement was observed for the (S) enantiomer. The displacement process resulting was competitive in nature, the two enantiomers of ketoprofen binding to the same binding site as the modifier. The investigation was extended to other nonsteroidal antiinflammatory drugs. The enantioselective binding inhibition was larger in the case of rac-naproxen and rac-suprofen with respect to the phenomenon observed in the case of rac-ketoprofen. The difference in circular dichroism spectroscopy was also used to characterize the binding of lithocholate to human serum albumin. This bile acid was proven to bind to site II on human serum albumin. The results, as obtained by displacement chromatography and difference circular dichroism spectroscopy, strongly support the hypothesized role of bile acids in inducing the enantioselective inhibition of ketoprofen binding to human serum albumin in patients suffering from liver diseases.

[Effect of anti-inflammatory drugs, alone and combined with ofloxacin, on the respiratory burst of human polymorphonuclear leukocytes]

The antibacterial activity of polymorphonuclear leukocytes (PMNs) is based on the production of superoxide anion and H(2)O(2) in the respiratory burst and can be impaired in different ways. The combination of an antibacterial agent and an antiinflammatory drug is quite common in immunodepressed patients whose respiratory burst of PMN could be impaired. In this study we examine in vitro the effect of pretreating (35 degrees C for 30 min) PMNs with the antiinflammatory drugs dexamethasone (0.4, 4 and 40 microgram/ml), methylprednisolone (0.37, 3.7 and 37 microgram/ ml), hydrocortisone (0.048, 0.48 and 4.8 microgram/ml), betamethasone (0.1, 1, 5 and 10 mg/ml), phenylbutazone (1000 microgram/ml) and acetylsalicylic acid (25, 250, 2500 microgram/ml) alone, and combined with 10 mg/ml of ofloxacin on the respiratory burst. Superoxide anion was measured by the cytochrome c reduction microtechnique and H(2)O(2) by phenol red. The antiinflammatory drugs alone decreased the production of H(2)O(2) (except dexamethasone and methylprednisolone) and superoxide anion (except betamethasone) from 15-45%, depending on the antiinflammatory drug and concentration, while ofloxacin increased the production of superoxide anion (20.2 +/- 6.7%). The combination of antiinflammatory drugs with ofloxacin neutralizes the inhibitory effect of the former on the respiratory burst of PMNs. It is therefore important to know the effect of drugs on the respiratory burst in order to choose those that have the same therapeutic effect without interfering with PMN functions.

Protective role of nitric oxide in indomethacin-induced gastric ulceration by a mechanism independent of gastric acid secretion

Gastric ulceration was induced in rats by i.p. injection of the non-steroidal anti-inflammatory drug (NSAID), indomethacin (IND) (30 mg kg(-1)). Pyloric ligation was carried out in each animal before injection to enable collection of the gastric juice. Three hours later, the animals were killed and their stomachs were removed. In the gastric juice, the amounts of mucin, pepsin and HCl were assessed. Gastric mucosa were scrapped for the determination of nitric oxide (NO) (as nitrite) after evaluation of the gastric ulcer index. The influence of arginine (ARG) (300 mg kg(-1)), a NO precursor, N(G)-nitro- l -arginine methyl ester (l -NAME) (50 mg kg(-1)), a non-selective constitutive nitric oxide synthase/inducible nitric oxide synthase (cNOS/iNOS) inhibitor, and the selective iNOS inhibitor aminoguanidine (AMG) (50 mg kg(-1)) were studied. Each NO modulator was injected i.p. 30 min before IND administration. Results indicated that IND elevated gastric acidity by 80% of the normal group, decreased non-significantly mucosal nitrite by 22% and exhibited a remarkably high ulcer index (chi = 17). Neither mucin nor pepsin levels were significantly altered. In comparison with the IND group, pretreatment with l -NAME caused a significant decrease in gastric HCl, further decrease in mucosal nitrite (50% of normal) and a two-fold increase in the ulcer index score (chi = 34), despite the decrease in HCl. AMG did not alter gastric acidity, decreased mucosal nitrite by 38% of the normal value and failed to alter significantly the ulcer index of IND. On the other hand, pretreatment with ARG did not alter the gastric acidity and raised mucosal nitrite by 10% above normal. Surprisingly, ARG improved the gastric ulcer score (chi = 1) almost similar to the normal score (chi = zero). Therefore, this study creates a new pathway for the potential treatment of NSAID gastric ulceration through modulation of NO synthesis, regardless of the effect on gastric acidity.

Biphasic regulation of NF-kappa B activity underlies the pro- and anti-inflammatory actions of nitric oxide

Expression of inducible NO synthase (iNOS) by macrophages is a prerequisite for the production of high output NO, which mediates many bactericidal and tumoricidal actions of these immune cells. The expression of iNOS in mammalian cells is governed predominantly by the transcription factor, NF-kappa B, which regulates the expression of many host defense proteins. In the present study, we characterize a novel, biphasic effect of NO on NF-kappa B activity in murine macrophages. This mechanism depends on the local concentration of NO and enables it both to up- and down-regulate the expression of host defense proteins including iNOS, cyclooxygenase-2, and IL-6. This biphasic activity of NO appears to play a pivotal role in the time course of activation of these immune cells and, by inference, in facilitating the initiation of a defense response against pathogenic stimuli and in its termination to limit tissue damage. This mechanism may explain at least in part the reported ability of NO to act in both a pro- and anti-inflammatory manner.

Neutral endopeptidase terminates substance P-induced inflammation in allergic contact dermatitis

Sensory nerve-derived neuropeptides such as substance P demonstrate a number of proinflammatory bioactivities, but less is known about their role in inflammatory skin disease. The cell surface metalloprotease neutral endopeptidase (NEP) is the principal proteolytic substance P-degrading enzyme. This study tests the hypothesis that the absence of NEP results in dysregulated inflammatory skin responses. The effector phase of allergic contact dermatitis (ACD) responses was examined in NEP(-/-) knockout and NEP(+/+) wild-type mice and compared with the irritant contact dermatitis response in these animals. NEP was found to be normally immunolocalized in epidermal keratinocytes and dermal blood vessels. The ACD ear swelling response was 2.5-fold higher in animals lacking NEP and was accompanied by a significant increase in plasma extravasation and infiltration of inflammatory leukocytes. The augmented ACD response in NEP(-/-) animals was abrogated by either administration of a neurokinin receptor 1 antagonist or by repeated pretreatment with topical capsaicin. Similar to NEP(-/-) mice, the acute inhibition of NEP in NEP(+/+) animals resulted in an augmented ACD response. In contrast to the ACD responses, little differences were observed in the irritant contact dermatitis response of NEP(-/-) compared with NEP(+/+) animals after epicutaneous application of the skin irritants croton oil or SDS. Thus, these results indicate that NEP and cutaneous neuropeptides have a significant role in the pathogenesis of ACD.

Cyclooxygenase 2 and the kidney

Cyclooxygenase metabolizes arachidonic acid to a family of bioactive fatty acids designated prostaglandins. Two isoforms of cyclooxygenase exist, designated COX1 and COX2. These isoforms are expressed in distinct but important areas of the kidney. COX1 predominates in vascular smooth muscle and collecting ducts, whereas COX2 predominates in the macula densa and nearby cells in the cortical thick ascending limb. COX2 is also highly expressed in medullary interstitial cells. Whereas COX1 expression does not exhibit dynamic regulation, COX2 expression is subject to regulation by several environmental conditions, including salt intake, water intake, medullary tonicity, growth factors, cytokines, and adrenal steroids. Recently, COX2-selective non-steroidal anti-inflammatory drugs have become widely available. Many of the renal effects of non-selective non-steroidal anti-inflammatory drugs (including sodium retention, decreased glomerular filtration rate, and effects on renin-angiotensin levels) appear to be mediated by the inhibition of COX2 rather than COX1. Therefore, in contrast to the gastrointestinal-sparing effects of COX2-selective non-steroidal anti-inflammatory drugs, when considering the kidney, the same caution must be applied when using COX2-selective inhibitors as has been used with traditional non-selective non-steroidal anti-inflammatory drugs.

[Effect of carrageenan and indomethacin on the growth of a murine fibrosarcoma]

In order to grow, solid tumors need to develop new blood vessels. Neoplastic cells secrete growth factors that stimulate angiogenesis and tumor growth. Since Carrageenan acts as in vitro blocking agent which interferes with growth factor-receptor binding, we tested its action in vivo in order to analyze its growth inhibition capability in an experimental murine fibrosarcoma model. Indomethacin was used as a non-steroidal anti-inflammatory agent to neutralize the inflammatory action of Carrageenan. A murine fibrosarcoma was induced with methylcholanthrene in Balb/c mice and maintained by serial passage of tumor cells in mice of the same strain. Tumor volume was evaluated measuring two dimensions and applying the formula V = 0.4 x d2 x D. The mice with tumors were separated into groups; one of them was used as control and the other ones were treated with Indomethacin, Carrageenan and Carrageenan-Indomethacin. Tumor volume was compared between groups using the Student t Test. We demonstrated that Carrageenan and Indomethacin inhibit tumor growth. The inhibitory action of Carrageenan is significantly higher than the antitumoral effect of either Indomethacin or Carrageenan-Indomethacin.

Occupational asthma caused by pyrazolone derivative used in silver halide photographic paper

Occupational asthma has been documented in workers exposed to a wide variety of chemical compounds. Reactive dyes have been described as causing occupational asthma in textile industry workers. We report a case of occupational asthma resulting from exposure to pyrazolone dye used in silver halide photographic paper. There is a need for both further surveys of workers exposed to other reactive dyes and careful preventive measures in the handling of such compounds.

[In vitro effects of L-carnitine on the inhibition of sperm mobility induced by FANS]

OBJECTIVE

We wanted to study the function of some substances present in the seminal fluid (PG and L. Carnitine), which, with different mechanisms, affected Spermatozoa motility, and to study the effect of other substances (F.A.N.S.), known also for their action on P.G.

PATIENTS AND METHODS

Ten samples of seminal fluid from healthy subjects were studied according to the indications of the World Health Organization (1992).

RESULTS

All the F.A.N.S. used (Cinnoxicam, Salicylic Acetyl Acid) had an inhibitory effect on motility, as did L. Carnitine at high doses. We thought it interesting to observe if L. Carnitine added to the seminal fluid before F.A.N.S. blocked their effects.

CONCLUSIONS

The pre-treatment with L. Carnitine had an "in vitro" buffering effect on F.A.N.S.

Nonsteroidal anti-inflammatory drugs, COX-2 and colorectal cancer

Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) has been associated with reduced risk of colorectal cancer. Moreover, the NSAID sulindac reduces the number and size of polyps in patients with familial adenomatous polyposis. The mechanisms of these effects of NSAIDs are not known but several lines of evidence suggest the involvement of the inhibition of the inducible isoform of prostaglandin H synthase (known as COX-2). Specific COX-2 inhibitors, showing an improved profile of gastrointestinal safety vis-à-vis conventional NSAIDs, provide interesting tools to probe the COX-2 dependence of the apparent protection against colorectal cancer associated with the use of NSAIDs.