Peroxiredoxin expression in the endocrine pancreas and their regulation by pro-inflammatory cytokines

Pro-inflammatory cytokines released from immune cells infiltrating the endocrine pancreas in Type 1 Diabetes (T1D) induce the generation of reactive oxygen and nitrogen species (ROS/RNS). Cytokines are in part cytotoxic to ƒÒ-cells via the production of peroxynitrite (ONOO-). ƒÒ-cell are weakly protected against the toxicity of ROS/RNS because of limited expression of antioxidant enzymes. The purpose of this study was to evaluate the expression and regulation of Peroxiredoxins (Prdxs/PRDXs), a new family of antioxidant enzymes in islet ƒÒ-cell. Peroxiredoxin 5 (Prdx5) is ubiquitously expressed in mammals and it exhibits a range of cellular roles including cytoprotective antioxidant defence. Human PRDX5 possesses a peroxynitrite reductase activity but its role in ƒÒ-cell defence was not investigated yet. In a first set of experiments, the localization of the Prdx family was analyzed in rodent pancreas. Prdx1 was preferentially found in the non-b-cells of the islet and in exocrine tissue. Prdx2, Prdx3 and Prdx5 were present in b and non-b-cells, while Prdx4 and Prdx6 were poorly expressed. Then, we investigated the modulation of Prdx mRNA and protein expression levels by cytokines in adult rat isolated islets. Prdx1, Prdx2 and Prdx3 expression was not modified while Prdx5 mRNA was upregulated. However, Prdx5 protein was downregulated, which could involve ubiquitination and proteasomal degradation. Little is known about the PRDX antioxidant enzyme expression in human islets. In a second set of experiments, we investigated the expression and regulation of the 6 PRDXs in human islet preparations facing the context of T1D pathogenesis. PRDX 2, 3, 5, 6 were observed in the exocrine part of the pancreas. PRDX2 and PRDX6 were preferentially expressed in islet ƒÑ cells rather than in ƒÒ cells. PRDX3 and PRDX5 were localized in ƒÑ cells as well as in ƒÒ cells. PRDX4 was detected neither in exocrine nor in endocrine tissue. Islets exposed to a mixture of cytokines showed a downregulation of PRDX2, 3, 5, 6 mRNA expression, as was also the case for PRDX5 protein. This study demonstrated that a clear difference between human and rodent species does exist in terms of tissue localization, expression and regulation of Prdxs by cytokines. Finally, we performed Prdx5 overexpression or silencing in insulin secreting cell line INS-1E. Overexpression of Prdx5 was effective against a stress induced by SIN-1 but not against the cytokines mixture. On the opposite, silencing Prdx5 expression decreased the cell viability. Then, the hypothesis that the vulnerability of islets to cytokines mixture was due to the Prdx5 downregulation was not demonstrated. However, the modification of Prdx5 expression would in part be responsible for the high sensitivity of ƒÒ-cell to peroxynitrite. In conclusion, this study featured the presence of some Prdxs/PRDXs in islet cells, and the regulation of their expression by cytokines. They intervene in protection against ONOO- toxicity but their implication against cytokine agression remain to be more precisely evaluated.(BIOL 3) -- UCL, 200

An evaluation of analytical and interpretative methodologies for the extraction and identification of lipids associated with pottery sherds from the site of Sagalassos, Turkey

Three lipid analysis methods were applied to extracts of archaeological potsherds from the ancient city of Sagalassos, south-west Turkey. In the fatty acid methyl ester fraction, obtained by selective transesterification of acylglycerols, the ratio of methyl palmitate to methyl stearate was determined. Secondly, by means of gas chromatography- combustion-isotope ratio mass spectrometry (GC-C-IRMS), stable carbon isotope ratios were measured for the same methyl esters. Finally, triglyceride composition was determined via high-performance liquid chromatography-mass spectrometry (HPLC-MS). All three methods can be used to trace the origin of animal fat. Agreement between them is reasonable, especially in recognizing ruminant adipose fat. One sample was found to be of dairy origin using both GC-C-IRMS and HPLC-MS. The advantages of the various methods are discussed. Variations in lipid composition were observed between samples from different periods and excavated in diverse areas within the city of Sagalassos.status: publishe

Intrauterine programming of the endocrine pancreas.

Epidemiological studies have revealed strong relationships between poor foetal growth and subsequent development of the metabolic syndrome. Persisting effects of early malnutrition become translated into pathology, thereby determine chronic risk for developing glucose intolerance and diabetes. These epidemiological observations identify the phenomena of foetal programming without explaining the underlying mechanisms that establish the causal link. Animal models have been established and studies have demonstrated that reduction in the availability of nutrients during foetal development programs the endocrine pancreas and insulin-sensitive tissues. Whatever the type of foetal malnutrition, whether there are not enough calories or protein in food or after placental deficiency, malnourished pups are born with a defect in their beta-cell population that will never completely recover, and insulin-sensitive tissues will be definitively altered. Despite the similar endpoint, different cellular and physiological mechanisms are proposed. Hormones operative during foetal life like insulin itself, insulin-like growth factors and glucocorticoids, as well as specific molecules like taurine, or islet vascularization were implicated as possible factors amplifying the defect. The molecular mechanisms responsible for intrauterine programming of the beta cells are still elusive, but two hypotheses recently emerged: the first one implies programming of mitochondria and the second, epigenetic regulation

Wine and olive oil permeation in pitched and non-pitched ceramics: relation with results from archaeological amphorae from Sagalassos, Turkey

Pitch compounds are frequently identified inside archaeological ceramic vessels. As their presence might affect the permeation of oil or wine into the ceramic fabric, experiments were conducted in which the diffusion of lipids or polyphenols into pitched and non-pitched modern vessels was followed by chemical analysis. Results show that the polyphenols of wine can intrude into the ceramics even through a pitch layer. Consequently, the absence of polyphenols in archaeological sherds is not due to their inability to reach the ceramic matrix under the pitch layer. By contrast, a pitch layer is quite effective to avoid oil intrusion into the ceramic matrix. Thus, it seems logical that oil amphorae would have been coated with pitch at the inside prior to use. Experiments in which the pitched ceramic was simultaneously exposed to oil and wine, show that the wine makes the pitch more permeable for the lipid compounds. These experimental data are confronted with residue analysis results obtained on amphorae fragments excavated in Sagalassos, Turkey. Pitch and oil were frequently found together. Based on a polyphenol test, indications for wine storage could only be obtained for two vessels. Against this background, the possible uses of the Sagalassos amphorae are discussed, and the traditional association of pine pitch with wine storage in archaeological amphorae is critically assessed.status: publishe

Brassicaceae seed oil identified as illuminant in Nilotic shells from a first millennium AD Coptic church in Bawit, Egypt

Burned greasy deposits were found inside shells of the large Nile bivalve Chambardia rubens, excavated in an eight- to tenth- century AD church of the Coptic monastery of Bawit, Egypt, and supposedly used as oil lamps. The residues were subjected to a combination of chromatographic residue analysis techniques. The rather high concentrations of unsaturated fatty acids, as analysed by gas chromatography (GC) in the methylated extract, suggest the presence of a vegetal oil. Analysis of the stable carbon isotopes (delta C-13 values) of the methyl esters also favoured plants over animals as the lipid source. In the search for biomarkers by GC coupled to mass spectrometry on a silylated extract, a range of diacids together with high concentrations of 13,14-dihydroxydocosanoate and 11,12-dihydroxyeicosanoate were found. These compounds are oxidation products of erucic acid and gondoic acid, which are abundantly present in seeds of Brassicaceae plants. Liquid chromatography coupled to mass spectrometry analysis showed low concentrations of unaltered triglycerides, but revealed sizeable amounts of triglycerides with at least one dihydroxylated acyl chain. The unusual preservation of dihydroxylated triglycerides and alpha,omega-dicarboxylic acids can be related to the dry preservation conditions. Analysis of the stereoisomers of the dihydroxylated fatty acids allows one to determine whether oxidation took place during burning of the fuel or afterwards. The results prove that the oil of rapeseed (Brassica napus L.) or radish (Raphanus sativus L.) was used as illuminant in early Islamic Egypt, and that not only ceramic lamps but also mollusk shells were used as fuel containers.status: publishe