RESUMEN
Continuous activation of the immune system inside a tissue can lead to remodelling of the tissue structure and creation of a specific microenvironment, such as during the tumour development. Chronic inflammation is a central player in stimulating changes that alter the tissue stroma and can lead to fibrotic evolution. In the colon mucosa, regulatory mechanisms, including TGF-ß1, avoid damaging inflammation in front of the continuous challenge by the intestinal microbiome. Inducing either DSS colitis or AOM colorectal carcinogenesis in AVN-Wistar rats, we evaluated at one month after the end of each treatment whether immunological changes and remodelling of the collagen scaffold were already in development. At this time point, we found in both models a general downregulation of pro-inflammatory cytokines and even of TGF-ß1, but not of IL-6. Moreover, we demonstrated by multi-photon microscopy the simultaneously presence of pro-fibrotic remodelling of the collagen scaffold, with measurable changes in comparison to the control mucosa. The scaffold was significantly modified depending on the type of induced stimulation. These results suggest that at one month after the end of the DSS or AOM inductions, a smouldering inflammation is present in both induced conditions, since the pro-inflammatory cytokines still exceed, in proportion, the local homeostatic regulation of which TGF-ß1 is a part (inflammatory threshold). Such an inflammation appears sufficient to sustain remodelling of the collagen scaffold that may be taken as a possible pathological marker for revealing pre-neoplastic inflammation.
RESUMEN
The urine from mice exposed to styrene vapors (600 and 1200 mg/m(3), 6 h) was analyzed for ring-oxidized metabolites of styrene. To facilitate the identification of metabolites in urine, the following potential metabolites were prepared: 2-, 3-, and 4-vinylphenol (2-, 3-, and 4-VP), 4-vinylpyrocatechol, and 2-, 3-, and 4-vinylphenylmercapturic acid (2-, 3-, and 4-VPMA). For the analysis of vinylphenols beta-glucuronidase-treated urine was extracted and derivatized with acetanhydride/triethylamine before injection into GC/MS. Three isomers, 2-, 3-, and 4-VP, were found in the exposed urine using authentic standards. Additionally, three novel minor urinary metabolites, arylmercapturic acids 2-, 3-, and 4-VPMA, were identified by LC-ESI-MS(2) by comparison with authentic standards. Excretion of the most abundant isomer, 4-VPMA, amounted to 535 +/- 47 nmol/kg and 984 +/- 78 nmol/kg, representing approximately 0.047 and 0.043% of the absorbed dose for the exposure levels of 600 and 1200 mg/m(3), respectively. The ratio of 2-VPMA, 3-VPMA, and 4-VPMA was approximately 2:1:6. In model reactions of styrene 3,4-oxide (3,4-STO) with N-acetylcysteine in aqueous solutions and of its methyl ester in methanol, 4-vinylphenol was always the main product, while 3-vinylphenol has never been detected. No mercapturic acid was found in the reaction of 3,4-STO with N-acetylcysteine in aqueous solution at pH 7.4 or 9.7, but a small amount of 4-VPMA methyl ester was detected by LC-ESI-MS after the reaction of 3,4-STO with N-acetylcysteine methyl ester. In contrast, no mercapturic acid was found in the reaction of 3,4-STO with N-acetylcysteine in aqueous solution at pH 7.4 or 9.7. These findings indicate a capability of 3,4-STO to react with cellular thiol groups despite its rapid isomerization to vinylphenol in an aqueous environment. Moreover, the in vivo formation of 2- and 3-isomers of both VP and VPMA, neither of which was formed from 3,4-STO in vitro, strongly suggests that another arene oxide, styrene 2,3-oxide, might be a minor metabolic intermediate of styrene.
