Yvan Larondelle

Dimethyl sulfoxide (DMSO) attenuates the inflammatory response in the in vitro intestinal Caco-2 cell model.

This study aimed to investigate dose effects of dimethyl sulfoxide (DMSO) (0.05-1%) on the intestinal inflammatory response in confluent- and differentiated-Caco-2 cells stimulated with interleukin (IL)-1β or a pro-inflammatory cocktail for 24 h. Cyclooxygenase-2 (COX-2) activity was assayed by incubating inflamed cells with arachidonic acid and then measuring prostaglandin-E(2) (PGE(2)) produced. Soluble mediators (IL-8, IL-6, macrophage chemoattractant protein-1 (MCP-1), and COX-2-derived PGE(2)) were quantified by enzyme immunoassays and mRNA expression of 33 proteins by high throughput TaqMan Low Density Array. Data showed that DMSO decreased induced IL-6 and MCP-1 secretions in a dose-dependent manner (P<0.05), but not IL-8; these effects were cell development- and stimulus- independent. Moreover, in IL-1β-stimulated confluent-cells, DMSO dose-dependently reduced COX-2-derived PGE(2) (P<0.05). DMSO at 0.5% decreased significantly mRNA levels of 14 proteins involved in the inflammatory response (including IL-6, IL-1α, IL-1β, and COX-2). Thus, DMSO at low concentrations (0.1-0.5%) exhibits anti-inflammatory properties in the in vitro intestinal Caco-2 cell model. This point is important to be taken into account when assessing anti-inflammatory properties of bioactive compounds requiring DMSO as vehicle, such as phenolic compounds, in order to avoid miss-interpretation of the results.

Epigenetic properties of the diarrhetic marine toxin okadaic acid: inhibition of the gap junctional intercellular communication in a human intestine epithelial cell line.

Okadaic acid (OA) is produced by several types of dinoflagellates (marine plankton) and has been implicated as the causative agent of diarrhetic shellfish syndrome. Previous studies have shown that okadaic acid is a tumor promoter and a specific potent inhibitor of protein phosphatases and protein synthesis. These effects in turn affect intracellular processes such as metabolism, contractility, gene transcription, and the maintenance of cytoskeletal structure. Gap junctional intercellular communication (GJIC) is a means of maintaining cellular homeostasis in organs, the disruption of which favors tumor cell growth. The GJIC involves the transfer of small water-soluble molecules through intercellular channels (gap junctions), composed of proteins called connexins. OA disrupts cellular homeostasis in Caco-2 cells through several mechanisms including protein synthesis inhibition, apoptosis, and clastogenic effects. The aim of this study was then to evaluate the expression of the connexin 43 (Cx 43) mRNA in relation with the cytotoxicity induced by OA (3.75–60xa0ng/ml) in a human colonic epithelial cell line in culture (Caco-2 cells). OA produced a dose-dependent inhibition of GJIC in Caco-2 cells, along with a parallel decrease in the expression of Cx 43 as shown by immunohistochemistry using anti-Cx 43 antibody. Since Cx 43 is implicated in the suppression of tumors and OA is a tumor promoter, the inhibition of GJIC may play an important role in its carcinogenesis. These data are discussed in relation to the toxicity of OA, total RNA synthesis, and possible specificity of Cx 43 inhibition in the GJIC.

An initiation codon mutation as a cause of beta-thalassemia in a Belgian family.

Nine asymptomatic members of a family of Belgian origin, spanning three generations, present typical features of heterozygous beta-thalassemia. Since no mutation was detected with a large panel of oligonucleotide probes, the thalassemia gene was investigated by direct sequencing of DNA segments amplified by the polymerase chain reaction. A T-->C transition was detected in the translation initiation codon (ATG). The mutation, which abolishes an Nco I restriction site, was further confirmed by enzymatic digestion as well as by dot-blot hybridization of the amplified products with allele-specific oligonucleotide probes. It produced a beta zero-thalassemia phenotype characterized by marked microcytosis and hypochromia, as well as by an in vitro beta/alpha chain synthesis ratio close to O.5. Search for haplotype linkage showed the mutation to be associated with haplotype IX [- + - + + + +].

The Use of Pomegranate (Punica granatum L.) Phenolic Compounds as Potential Natural Prevention Against IBDs

Phenolic compounds (PCs) are plant secondary metabolites that are integral part of the “normal” human diet. The daily intake of PCs depends on the diet but is commonly evaluated at ca. 1g/day for people who eat several fruits and vegetables per day (Scalbert & Williamson, 2000). PCs may be interesting to prevent the development of inflammatory diseases, more particularly in the gastrointestinal tract, where their concentration may reach levels of up to several hundred μM (Scalbert & Williamson, 2000). Many studies have indeed reported on anti-inflammatory properties of different PCs (see (Calixto et al., 2004; Rahman et al., 2006; Romier et al., 2009; Shapiro et al., 2009), for reviews). Pomegranate (Punica granatum L.) belongs to the Punicaceae family, which includes only two species. More than 500 cultivars of Punica granatum exist with specific characteristics such as fruit size, exocarp and aril color, etc. Originating from the Middle East, pomegranate is now widely cultivated throughout the world, and also widely consumed. Pomegranate has been used for centuries in the folk medicine of many cultures. As described in the review of Lansky et al. (2007), the bark and the roots are believed to have anthelmintic and vermifuge properties, the fruit peel has been used as a cure for diarrhea, oral aphthae, and as a powerful astringent, the juice as a blood tonic, and the flowers as a cure for diabetes mellitus. Numerous investigations have highlighted the anti-inflammatory potential of the PCs found in this fruit, and more especially of hydrolysable tannins called ellagitannins (ETs), which are mainly located in pomegranate peels. These ETs are extracted into the juice upon commercial processing of the whole fruit (Gil et al., 2000). This chapter first describes the PCs found in pomegranate fruit, then focuses on ETs in relation to their metabolic fate after ingestion as well as to their anti-inflammatory properties on the intestine, and finally discusses gut microflora modifications following pomegranate ingestion and their impact on intestinal inflammation.