Effects of the prostaglandin analogue misoprostol on inflammatory mediator release by human monocytes.

The effect of misoprostol (M) on IL-1 beta, TNF-alpha, and lipid mediator release (assessed by RIA) by adherent (assessed by electron microscopy) human monocytes were studied in vitro. Human monocytes stimulated with E. Coli-derived lipopolysaccharide showed an increase in both IL-1 beta and TNF-alpha release. Incubation of the monocytes with LPS and M (18 hrs.), resulted in a reduction of both IL-1 beta and TNF-alpha levels. Leukotriene B4 levels did not increase in response to LPS or M. LPS also caused an increase in thromboxane (TXB2). M decreased TXB2 levels. 6-keto PGF1 alpha (6KP). Incubation with LPS and M stimulated release. LPS caused an increase in PGE2 levels. M (100 microM) caused an increase in PGE2 levels, M (1 microM) had no effect on PGE2. These data suggest a possible immunomodulatory role for misoprostol in inflammatory diseases.     

Effect of the leukotriene B4 receptor antagonist SC-41930 on colonic inflammation in rat, guinea pig and rabbit

Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract that includes ulcerative colitis and Crohn's disease. Leukotriene B4 is thought to be a prominent proinflammatory mediator in these diseases, in that leukotriene B4 levels are increased in the colonic mucosa of inflammatory bowel disease patients and there is increased polymorphonuclear leukocyte infiltration of these tissues. We evaluated the efficacy of 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-3,4-dihydro-8-propyl -2H-1-benzopyran-2-carboxylic acid (SC-41930), a potent, orally active leukotriene B4 receptor antagonist, in a model of inflammatory bowel disease. Colonic mucosal inflammation was induced in rats, guinea pig and rabbits by rectal instillation of a dilute solution of acetic acid. Twenty-four hours later, mucosal levels of myeloperoxidase (a marker enzyme for neutrophil infiltration) and extravasation of i.v. administered Evans blue dye (a marker of vascular disruption and increased permeability) were measured. Tissues were also evaluated histologically. The animals received either SC-41930 or vehicle, intrarectally, 30 min after or 1 hr before and 1 hr after the acetic acid. When given 30 min after acetic acid instillation SC-41930 prevented the rise in myeloperoxidase and dye extravasation observed in the acetic acid inflammed tissue. The SC-41930-treated tissues were less edematous and had fewer neutrophils within the subepithelial space. Median effective dose (ED50) values for vascular protection were approximately 20 mg/kg for both rat and guinea pig. ED50 values for inhibition of granulocyte accumulation were 20 mg/kg for rat, 24 mg/kg for guinea pig and 30 mg/kg for rabbit. These data indicate that SC-41930 is effective locally to prevent acute colonic inflammation.     

Identification and characterization of rhesus macaque interleukin-8

To establish a direct link between IL-8 and inflammation in vivo, we first isolated the gene encoding rhesus macaque IL-8. The open reading frame directs the translation of a 101 amino acid (aa) precursor, which is 94% identical to human IL-8. Rhesus IL-8 was expressed in bacteria and purified to homogeneity with ion-exchange chromatography. Pure rhesus IL-8 was biologically active as measured by its ability to bind specifically to either rhesus (K _d =0.5 nM) or human (K _d =2 nM) IL-8 receptors and to promote in vitro chemotaxis of rhesus (EC₅₀=2 nM) or human neutrophils (EC₅₀=4 nM). Moreover, a mouse monoclonal antibody, DM/C7, which neutralizes human IL-8 activity, also recognized and neutralized (IC₅₀=0.5–3.0 ng/ml) rhesus IL-8 in vitro. Systemic administration of DM/C7 completely inhibited the dermal inflammation of rhesus ears induced by the external application of phorbol myristoyl acetate. These observations reveal that rhesus IL-8 is structurally and functionally similar to human IL-8 and suggests that IL-8 plays a prominent role in a primate model of inflammation.     

Tissue distribution of N-acetyltransferase 1 and 2 catalyzing the N-acetylation of 4-aminobiphenyl and O-acetylation of N-hydroxy-4-aminobiphenyl in the congenic rapid and slow acetylator Syrian hamster

N-acetyltransferase 1 (NAT1) and 2 (NAT2) enzymes catalyzing both deactivation (N-acetylation) and activation (O-acetylation) of arylamine carcinogens such as 4-aminobiphenyl (ABP) were investigated in a Syrian hamster model congenic at the NAT2 locus. NAT2 catalytic activities (measured with p-aminobenzoic acid) were significantly (P < 0.001) higher in rapid than slow acetylators in all tissues (except heart and prostate where activity was undetectable in slow acetylators). NAT1 catalytic activities (measured with sulfamethazine) were low but detectable in most tissues tested and did not differ significantly between rapid and slow acetylators. ABP N-acetyltransferase activity was detected in all tissues of rapid acetylators but was below the limit of detection in all tissues of slow acetylators except liver where it was about 15-fold lower than rapid acetylators. ABP N-acetyltransferase activities correlated with NAT2 activities (r2 = 0.871; P < 0.0001) but not with NAT1 activities (r2 = 0.132; P > 0.05). Levels of N-hydroxy-ABP O-acetyltransferase activities were significantly (P < 0.05) higher in rapid than slow acetylator cytosols for many but not all tissues. The N-hydroxy-ABP O-acetyltransferase activities correlated with ABP N-acetyltransferase activities (r2 = 0.695; P < 0.0001) and NAT2 activities (r2 = 0.521, P < 0.0001) but not with NAT1 activities (r2 = 0.115; P > 0.05). The results suggest widespread tissue distribution of both NAT1 and NAT2, which catalyzes both N- and O-acetylation. These conclusions are important for interpretation of molecular epidemiological investigations into the role of N-acetyltransferase polymorphisms in various diseases including cancer.     

Effects of single nucleotide polymorphisms in human N-acetyltransferase 2 on metabolic activation (O-acetylation) of heterocyclic amine carcinogens

N-Acetyltransferase 2 (NAT2) catalyzes the O-acetylation of N-hydroxy heterocyclic amines such as N-hydroxy-2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (N--OH--MeIQx) and N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (N--OH --PhIP) to DNA binding metabolites that initiate mutagenesis and carcinogenesis. NAT2 acetylator phenotype is associated with increased cancer risk. Single nucleotide polymorphisms (SNPs) have been identified in the NAT2 coding region. Although the effects of these SNPs on N-acetyltransferase activity have been reported, very little is known regarding their effects on O-acetylation activity. To investigate the functional consequences of SNPs in the NAT2 coding region on the O-acetylation of N-hydroxy heterocyclic amines, reference NAT2*4 and NAT2 variant alleles possessing one were cloned and expressed in yeast (Schizosaccaromyces pombe). T111C, C282T, C481T, C759T, and A803G (K268R) SNPs did not significantly (p > 0.05) modify O-acetylation catalysis with N--OH--PhIP or N--OH--MeIQx. C190T (R64W), G191A (R64Q), T341C (I114T), A434C (E145P), G590A (R197Q) and A845C (K282T) significantly (p < 0.01) reduced the O-acetylation of both N--OH--PhIP and N--OH--MeIQx, whereas G857A (G286E) significantly (p < 0.05) decreased catalytic activity towards the O-acetylation of N--OH--MeIQx but not N--OH--PhIP. These results have important implications towards the interpretation of molecular epidemiological studies of NAT2 genotype and cancer risk.     

Inflammatory Response After Laparoscopic Versus Open Resection of Colorectal Liver Metastases: Data From the Oslo-CoMet Trial

Laparoscopic and open liver resection have not been compared in randomized trials. The aim of the current study was to compare the inflammatory response after laparoscopic and open resection of colorectal liver metastases (CLM) in a randomized controlled trial.This was a predefined exploratory substudy within the Oslo CoMet-study. Forty-five patients with CLM were randomized to laparoscopic (n = 23) or open (n = 22) resection. Ethylenediaminetetraacetic acid-plasma samples were collected preoperatively and at defined time points during and after surgery and snap frozen at −80 ^oC. A total of 25 markers were examined using luminex and enzyme-linked immunosorbent assay techniques: high-mobility box group 1(HMGB-1), cell-free DNA (cfDNA), cytokines, and terminal C5b-9 complement complex complement activation.Eight inflammatory markers increased significantly from baseline: HMGB-1, cfDNA, interleukin (IL)-6, C-reactive protein, macrophage inflammatory protein -1β, monocyte chemotactic protein -1, IL-10, and terminal C5b-9 complement complex. Peak levels were reached at the end of or shortly after surgery. Five markers, HMGB-1, cfDNA, IL-6, C-reactive protein, and macrophage inflammatory protein -1β, showed significantly higher levels in the open surgery group compared with the laparoscopic surgery group.Laparoscopic resection of CLM reduced the inflammatory response compared with open resection. The lower level of HMGB-1 is interesting because of the known association with oncogenesis.     

Effect of a leukotriene B4 receptor antagonist on leukotriene B4-induced neutrophil chemotaxis in cavine dermis

Leukotriene B₄ (LTB₄) is a proinflammatory product of arachidonic acid metabolism that has been implicated as a mediator in a number of inflammatory diseases. When injected intradermally into the cavine, LTB₄ elicits a dose-dependent immigration (chemotaxis) of neutrophils (PMNs) into the injection sites as assessed by the presence of a neutrophil marker enzyme myeloperoxidase. SC-41930 {7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxy]-3,4-dihydro-8-propyl-2H-l-benzopyran-2-carboxylic acid, a potent LTB₄ receptor antagonist inhibited the chemotactic actions of LTB₄ when coadministered into the dermal site and when given intravenously or orally with ED₅₀ values of 200 ng, 0.5 mg/kg, and 0.6 mg/ kg respectively. This compound may well have application in disease states, such as inflammatory bowel disease and psoriasis, where LTB₄ is implicated as a proinflammatory mediator.     

Interleukin 8 and mast cell-generated tumor necrosis factor-α in neutrophil recruitment

In the reverse passive Arthus reaction in mouse skin and immune injury of mouse dermal basement membrane, neutrophil (PMN) infiltration in mast cell deficient WBB6F₁-W/W^v (W/W^v) mice was only 40% of that in WBB6F₁-+/+ (+/+) mice that had a normal mast cell repertoire. An anti-tumor necrosis factor- (TNF-) monoclonal antibody (mAb) decreased PMN infiltration by 35–80% in +/+ but not W/W^v mice. In addition, an anti-human interleukin-8 (IL-8) MAb, DM/C7, inhibited PMN infiltration of the skin induced by either intradermal administration of recombinant human IL-1 or immune complex deposition. In both models of immune complex injury, DM/C7 reduced PMN infiltration by 40–60% in +/+ mice but not W/W ^v mice. PMN infiltration and the sensitivity of this infiltration to anti-TNF- or DM/C7 MAb in W/W^v mice whose mast cell population had been restored was indistinguishable from the influx observed in +/+ mice. These data suggest that TNF-, IL-8, and mast cells play a fundamental role in PMN recruitment following immune complex injury.     

Specific inhibitors of inducible nitric oxide synthase: Efficacy in a rodent model of sepsis

Inflammation Research -