Anti-Inflammatory Effects of Hyperbaric Oxygenation during DSS-Induced Colitis in BALB/c Mice Include Changes in Gene Expression of HIF-1α, Proinflammatory Cytokines, and Antioxidative Enzymes.

Reactive oxygen species (ROS) and nitrogen species have an indispensable role in regulating cell signalling pathways, including transcriptional control via hypoxia inducible factor-1α (HIF-1α). Hyperbaric oxygenation treatment (HBO2) increases tissue oxygen content and leads to enhanced ROS production. In the present study DSS-induced colitis has been employed in BALB/c mice as an experimental model of gut mucosa inflammation to investigate the effects of HBO2 on HIF-1α, antioxidative enzyme, and proinflammatory cytokine genes during the colonic inflammation. Here we report that HBO2 significantly reduces severity of DSS-induced colitis, as evidenced by the clinical features, histological assessment, impaired immune cell expansion and mobilization, and reversal of IL-1ß, IL-2, and IL-6 gene expression. Gene expression and antioxidative enzyme activity were changed by the HBO2 and the inflammatory microenvironment in the gut mucosa. Strong correlation of HIF-1α mRNA level to GPx1, SOD1, and IL-6 mRNA expression suggests involvement of HIF-1α in transcriptional regulation of these genes during colonic inflammation and HBO2. This is further confirmed by a strong correlation of HIF-1α with known target genes VEGF and PGK1. Results demonstrate that HBO2 has an anti-inflammatory effect in DSS-induced colitis in mice, and this effect is at least partly dependent on expression of HIF-1α and antioxidative genes.

Influence of small doses of various drug vehicles on acetaminophen-induced liver injury.

The biological effects of drug vehicles are often overlooked, often leading to artifacts in acetaminophen-induced liver injury assessment. Therefore, we decided to investigate the effect of dimethylsulfoxide, dimethylformamide, propylene glycol, ethanol, and Tween 20 on acetaminophen-induced liver injury. C57BL/6 male mice received a particular drug vehicle (0.6 or 0.2 mL/kg, i.p.) 30 min before acetaminophen administration (300 mg/kg, i.p.). Control mice received vehicle alone. Liver injury was assessed by measuring the concentration of alanine aminotransferase in plasma and observing histopathological changes. The level of reduced glutathione (GSH) was assessed by measuring total nonprotein hepatic sulfhydrils. Dimethylsulfoxide and dimethylformamide (at both doses) almost completely abolished acetaminophen toxicity. The higher dose of propylene glycol (0.6 mL/kg) was markedly protective, but the lower dose (0.2 mL/kg) was only slightly protective. These solvents also reduced acetaminophen-induced GSH depletion. Dimethylformamide was protective when given 2 h before or 1 h after acetaminophen administration, but was ineffective if given 2.5 h after acetaminophen. Ethanol at the higher dose (0.6 mL/kg) was partially protective, whereas ethanol at the lower dose (0.2 mL/kg) as well as Tween 20 at any dose had no influence. None of the vehicles (0.6 mL/kg) was hepatotoxic per se, and none of them was protective in a model of liver injury caused by D-galactosamine and lipopolysaccharide.

The influence of alpha-, beta-, and gamma-melanocyte stimulating hormone on acetaminophen induced liver lesions in male CBA mice.

Research over the past decade has indicated that melanocortin peptides are potent inhibitors of inflammation and a promising source of new anti-inflammatory and cytoprotective therapies. The purpose of the present paper is to compare protective effects of alpha-, beta-, and gamma-melanocyte stimulating hormone on acetaminophen induced liver lesions in male CBA mice. Acetaminophen was applied intragastrically in a dose of 150 mg/kg, and tested substances were applied intraperitoneally 1 hour before acetaminophen. Mice were sacrificed after 24 hours and intensity of liver injury was estimated by measurement of plasma transaminase activity (AST and ALT) and histopathological grading of lesions. It was found that alpha-, beta-, and gamma-MSH decrease intensity of lesions by both criteria in a dose-dependent manner.

The effect of cyclic adenosine monophosphate (cAMP) on acute liver toxicity in mice induced by D-galactosamine and lipopolysaccharide.

The aim of this study was to examine the effect of cyclic adenosine monophosphate (cAMP) and its possible interference/synergism with calcium channel blocker in mice with acute liver injury induced with D-galactosamine (D-GalN) and lipopolysaccharide (LPS). C57Bl/6 mice were given i.p. simultaneously 300 mg/kg D-GalN and LPS 0.01 mg/kg. This treatment induced severe hepatitis, as evidenced by high mortality (80-90%) of control mice and large increase in concentration of aminotransferases in plasma (AST, ALT). Injection of stabile analogue of cAMP (dibutyryl-cAMP, db-cAMP) one hour before hepatotoxic agents increased survival of mice in dose-dependent manner and in medium dose significantly decreased plasma ALT level. Similar (protective) effect had also verapamil, calcium channel blocker, when given in non toxic doses and at the same time schedule as db-cAMP Combination of db-cAMP and verapamil had not synergistic effect in protection from D-GalN+LPS hepatotoxicity; the survival of mice was similar to that seen in protection caused by each agent alone.

The role of prostacyclin in modifying acute hepatotoxicity of acetaminophen in mice.

Prostaglandins (PGs) are lipid compounds that mediate the variety of physiological and pathological functions in almost all body tissues and organs. Prostacyclin (prostaglandin 12, PGI2), which is synthesized by the vascular endothelium, is a potent vasodilator, inhibits the aggregation of platelets in vitro and has cytoprotective effect on gastrointestinal mucosa. The aim of this study was to determine whether PGI2 is playing a role in host defense to toxic effect of acetaminophen (APAP). This was investigated in C57Black/6 mice which were intoxicated with single lethal or high sublethal dose of APAP. APAP was administered to mice by gastric lavage and PGI2 agonists or antagonists were given intraperitoneally (i.p.) 30 minutes before or 2 hours after administration of APAP. The toxicity of APAP was determined by observing the survival of mice during 48 hours, by measuring the concentration of alanine-aminotransferase (ALT) in plasma 20-24 hours after APAP administration, and by liver histology. Mice were given either pure PGI2 (PGI2 sodium salt), its stable agonist (iloprost) or inhibitor of prostacyclin (IP)-receptor (CAY-10441). The results have shown that PGI2 exibits a strong hepatoprotective effect when it was given to mice either before or after APAP (both increase of survival of mice and decrease of plasma ALT levels were statistical significant). Iloprost has not shown a similar effect and CAY-10441 increased toxic effect of APAP if given 2 hours after its administration. Histopathological changes in liver generally support these findings. These investigations support the view that PGI2 is involved in defense of organism to noxious effects of xenobiotics on liver.

Vasodilatory prostaglandins in perinatal hypoxic brain damage.

Prostaglandin (PGE2 and PGI2) synthesis was determined in the cerebrospinal fluid (CSF) and serum of 19 hypoxic neonates at the age of 5-96 hours by using Enzyme Linked Immunosorbent Assay (ELISA) method. Control group consisted of 8 children of the same age whose samples were taken due to initial suspicion of neonatal meningitis. The prostaglandin concentrations in CSF were correlated with initial hypoxic-ischemic encephalopathy (HIE) stage and neurological findings of patients at the age of 12 months. The values of PGE2 and PGI2 in the CSF of children with perinatal hypoxia (PNH) were significantly higher than in the children from the control group. The values of PGI2 in serum were significantly higher than in "CSF" of patients with PNH. Although average values of PGE2 and PGI2 in the liquor were higher in children with advanced stage of HIE, the differences between different stages were not statistically significant. We did not find any significant correlation between average concentrations ofprostaglandins and neurological findings of the 12-month-old children.

Angiotensin converting enzyme activity and nitric oxide level in serum patients with dehydration.

Angiotensin converting enzyme (ACE) and nitric oxide (NO) have been suggested to be involved in the regulation of fluid homeostasis. In the present investigation, ACE activity and NO levels were determined in serum of 20 patients (10 men and 10 women) with dehydration caused by gastroenterocolitis and 20 healthy individuals (10 men and 10 women). Serum and tissue ACE activity was determined by spectrophotometric method using hippuryl-l-histidyl-l-leucine (Hip-His-Leu) as a substrate. NO synthesis was determined by measuring the products of NO, nitrite and nitrate. The concentration of nitrites was determined by classic colorimetric method using Griess reagent. Nitrate concentration was determined indirectly by their reduction with elementary zinc into nitrite. Results have shown that serum ACE activity in patients with dehydration (36,46+/-2,74 U/L) is statistically higher then in healthy individuals (28,71+/-1,77 U/L, p<0,05). The average level of nitrites/nitrates in serum of patients with dehydration (30,57+/-1,05 microM; mean +/- SEM) is also statistically higher then in healthy individuals (12,44+/-0,60 microM, p<0,0001). There was no correlation between ACE activity and NO production. The results indicate that ACE and NO may participate in the regulation of the alteration in blood flow and in the regulation of the water balance in patients with dehydration.

A comparison of blood and cerebrospinal fluid cytokines (IL-1ß, IL-6, IL-18, TNF-α) in neonates with perinatal hypoxia.

Perinatal hypoxia-ischemia is a specific and important pathological event in neonatal care practice. The data on relationship between the concentrations of cytokines in blood and cerebrospinal fluid (CSF) and perinatal brain injury are scarce. The aim of this study is to evaluate changes in interleukin (IL-1ß, IL-6, and IL-18) and tumor necrosis factor alpha (TNF-α) levels in newborns with perinatal hypoxia (PNH). CSF and serum samples of 35 term and near-term (35-40 weeks) newborns with PNH, at the age of 3-96 hours, were analyzed using enzyme-linked immunosorbent assay. Control group consisted of 25 non-asphyxic/non-hypoxic infants of the same age sampled for clinically suspected perinatal meningitis, but proven negative and healthy otherwise. The cytokine values in CSF and serum samples were determined in relation to initial hypoxic-ischemic encephalopathy (HIE) staged according the Sarnat/Sarnat method, and compared with neurological outcome at 12 months of age estimated using Amiel-Tison procedure. The concentrations of IL-6 and TNF-α in serum of PNH patients were significantly higher compared to control group (p = 0.0407 and p = 0.023, respectively). No significant difference between average values of cytokines in relation to the stage of HIE was observed. Significantly higher levels of IL-6 and IL-18 corresponded to a mildly abnormal neurological outcome, while higher levels of IL-6 and TNF-α corresponded to a severely abnormal neurological outcome, at 12 months of age. Elevated serum levels of IL-6 and TNF-α better corresponded with hypoxia/ischemia compared to CSF values, within 96 hours of birth. Also, higher serum levels of IL-6, TNF-α, and IL-18 corresponded better with abnormal neurological outcome at 12 months of age, compared to CSF values.

The effect of glucagon and cyclic adenosine monophosphate on acute liver damage induced by acetaminophen.

Recent investigations suggest that glucagon might have a potentially important hepatoprotective activity. We investigated the effect of glucagon in a model of acetaminophen-induced liver injury. CBA male mice were injected intraperitoneally with a lethal (300 mg/kg) or sublethal (150 mg/kg) dose of acetaminophen. The liver injury was assessed by observing the survival of mice, by liver histology and by measuring the concentration of alanine-aminotransferase (ALT). Inducible nitric oxide synthase (iNOS) and nuclear factor kappa B (NF-κB) protein expressions were determined immunohistochemically. Hepatic levels of reduced glutathione (GSH) and cyclic adenosine monophosphate (cAMP) were also measured. Results show that glucagon, dose and time dependently, protects against acetaminophen-induced hepatotoxicity. This protection was achieved with a dose of 0.5 mg/kg of glucagon given intraperitoneally 15 min before or 1 h after acetaminophen. Treatment of animals with acetaminophen elevated ALT and nitrite/nitrate concentration in the plasma, enhanced iNOS and NF-κB expression and reduced GSH and cAMP concentration in the liver. Animals treated with glucagon had higher hepatic cAMP level, lower ALT and nitrite/nitrate concentration in plasma and lower expression of iNOS in liver cells than animals in control group, whereas there was no difference in the expression of NF-κB. Glucagon did not prevent the loss of GSH content caused by acetaminophen. Our investigation indicates that glucagon has a moderately protective effect against acetaminophen-induced liver injury, which is, at least partially, mediated through the downregulation of iNOS and through the increase in hepatic cAMP content, but it is not mediated through the modulation of NF-κB activity.

The role of prostaglandin E2 in acute acetaminophen hepatotoxicity in mice.

Prostaglandin E2 (PGE2), which is synthesized by many cell types, has a cytoprotective effect in the gastrointestinal tract and in several other tissues and cells. On the other hand, overdose or chronic use of a high dose of acetaminophen (Paracetamol, APAP) is a major cause of acute liver failure in the western world. These observations prompted us to investigate whether PGE2 plays a role in host defence to toxic effect of APAP. (CBAT6T6xC57Bl/6)F1 hybrid mice of both sexes were intoxicated with a single lethal or high sublethal dose of APAP, which was administered to animals by oral gavage. Stabile analogue of PGE2, 16,16-dimethyl PGE2 (dmPGE2), or inhibitor of its production, CAY10526, were given intraperitoneally (i.p.) 30 minutes before or 2 hours after APAP administration. The toxicity of APAP was determined by observing the survival of mice during 48 hours, by measuring concentration of alanine-aminotransferase (ALT) in plasma 20-22 hours after APAP administration and by liver histology. The results have shown that PGE2 exhibits a strong hepatoprotective effect when it is given to mice either before or after APAP, while CAY10526 demonstrated mainly the opposite effect. Immunohistochemical or immunofluorescent examinations in the liver tissue generally support these findings, suggesting that PGE2 inhibited APAP-induced activation of nuclear factor kappa B (NF-kappaB). Similarly, PGE2 down regulated the activity of inducible nitric oxide synthase (iNOS), which was up regulated by APAP. Thus, by these and perhaps by other mechanisms, PGE2 contributes to the defence of the organism to noxious effects of xenobiotics on the liver.

Cyclic adenosine 5'-monophosphate in synovial fluid of rheumatoid arthritis and osteoarthritis patients.

The relationship between synovial fluid (SF) cAMP level and IL-18 and PGE2 SF levels in rheumatoid arthritis (RA) and osteoarthritis (OA) patients, and between SF cAMP level and disease as well as inflammatory activity in RA were investigated in 17 RA and 19 OA patients. Erythrocyte sedimentation rate (ESR), serum (S) C-reactive protein (CRP) level and SF IL-18 level were higher in RA than in OA patients. SF PGE2 level was similar in both groups. SF cAMP level was higher in OA than in RA patients. In RA patients, SF cAMP level showed negative correlation with Disease Activity Score including a 28-joint count and S CRP, ESR and SF IL-18 level. The results suggest that cAMP promotes anti-inflammatory response in RA and OA patients, which is higher in the latter. Promotion of anti-inflammatory response by cAMP elevating agents might be useful in the treatment of RA.