Advanced glycation end products regulate extracellular matrix protein and protease expression by human glomerular mesangial cells

Advanced glycation end products (AGEs) may play a role in the pathogenesis of diabetic nephropathy, by modulating extracellular matrix turnover. AGEs are known to activate specific membrane receptors, including the receptor for AGE (RAGE). In the present study, we analyzed the various receptors for AGEs expressed by human mesangial cells and we studied the effects of glycated albumin and of carboxymethyl lysine on matrix protein and remodelling enzyme synthesis. Membrane RAGE expression was confirmed by FACS analysis. Microarray methods, RT-PCR, and Northern blot analysis were used to detect and confirm specific gene induction. Zymographic analysis and ELISA were used to measure the induction of tPA and PAI-1. We show herein that cultured human mesangial cells express AGE receptor type 1, type 2 and type 3 and RAGE. AGEs (200 microg/ml) induced at least a 2-fold increase in mRNA for 10 genes involved in ECM remodelling, including tPA, PAI-1 and TIMP-3. The increase in tPA synthesis was confirmed by fibrin zymography. The stimulation of PAI-1 synthesis was confirmed by ELISA. AGEs increased PAI-1 mRNA through a signalling pathway involving reactive oxygen species, the MAP kinases ERK-1/ERK-2 and the nuclear transcription factor NF-kappaB, but not AP-1. Carboxymethyl lysine (CML, 5 microM), which is a RAGE ligand, also stimulated PAI-1 synthesis by mesangial cells. In addition, a blocking anti-RAGE antibody partially inhibited the AGE-stimulated gene expression and decreased the PAI-1 accumulation induced by AGEs and by CML. Inhibition of AGE receptors or neutralization of the protease inhibitors TIMP-3 and PAI-1 could represent an important new therapeutic strategy for diabetic nephropathy.

Systemic levels of the anti-inflammatory decoy receptor soluble RAGE (receptor for advanced glycation end products) are decreased in dogs with inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a common condition in dogs, and a dysregulated innate immunity is believed to play a major role in its pathogenesis. S100A12 is an endogenous damage-associated molecular pattern molecule, which is involved in phagocyte activation and is increased in serum/fecal samples from dogs with IBD. S100A12 binds to the receptor of advanced glycation end products (RAGE), a pattern-recognition receptor, and results of studies in human patients with IBD and other conditions suggest a role of RAGE in chronic inflammation. Soluble RAGE (sRAGE), a decoy receptor for inflammatory proteins (e.g., S100A12) that appears to function as an anti-inflammatory molecule, was shown to be decreased in human IBD patients. This study aimed to evaluate serum sRAGE and serum/fecal S100A12 concentrations in dogs with IBD. Serum and fecal samples were collected from 20 dogs with IBD before and after initiation of medical treatment and from 15 healthy control dogs. Serum sRAGE and serum and fecal S100A12 concentrations were measured by ELISA, and were compared between dogs with IBD and healthy controls, and between dogs with a positive outcome (i.e., clinical remission, n=13) and those that were euthanized (n=6). The relationship of serum sRAGE concentrations with clinical disease activity (using the CIBDAI scoring system), serum and fecal S100A12 concentrations, and histologic disease severity (using a 4-point semi-quantitative grading system) was tested. Serum sRAGE concentrations were significantly lower in dogs with IBD than in healthy controls (p=0.0003), but were not correlated with the severity of histologic lesions (p=0.4241), the CIBDAI score before (p=0.0967) or after treatment (p=0.1067), the serum S100A12 concentration before (p=0.9214) and after treatment (p=0.4411), or with the individual outcome (p=0.4066). Clinical remission and the change in serum sRAGE concentration after treatment were not significantly associated (p=0.5727); however, serum sRAGE concentrations increased only in IBD dogs with complete clinical remission. Also, dogs that were euthanized had significantly higher fecal S100A12 concentrations than dogs that were alive at the end of the study (p=0.0124). This study showed that serum sRAGE concentrations are decreased in dogs diagnosed with IBD compared to healthy dogs, suggesting that sRAGE/RAGE may be involved in the pathogenesis of canine IBD. Lack of correlation between sRAGE and S100A12 concentrations is consistent with sRAGE functioning as a non-specific decoy receptor. Further studies need to evaluate the gastrointestinal mucosal expression of RAGE in healthy and diseased dogs, and also the formation of S100A12-RAGE complexes.

Etude de l'importance socio-économique des produits agricoles et des produits forestiers ligneux en vue d'une amélioration des revenus de la population locale. Cas de la zone de Mandraka

La zone de Mandraka, située sur la première falaise orientale, constitue une région typiquement forestière dont la topographie ne favorise pas l’extension agricole. Cependant, compte tenu des besoins de sécurisation alimentaire, le besoin graduel en terres fait que la population se trouve dans l’obligeance d’accroître les zones d’agriculture et ainsi de recourir aux ressources forestières. Cette étude dessine alors comme objectif de définir les lignes d’actions principales combinant la gestion des ressources agricoles et la valorisation durable des ressources forestières. Aussi, des enquêtes socioéconomiques (formelles et informelles) ont été entreprises afin de parvenir aux résultats escomptés. Malgré les efforts en matière de valorisation agricole, l’autosuffisance alimentaire reste encore un problème fondamental à surmonter. De ce fait, le revenu agricole ne constitue que 22,54% du revenu des ménages. Il est également constaté que l’exploitation forestière évaluée prometteuse (61,07% du revenu) semble majorer les intérêts des grands collecteurs au détriment de la masse paysanne. Par conséquent, les difficultés quant aux besoins financiers persistent et les actions tendent vers la production (exploitation) à outrance, de plus que la demande en ville ne cesse d’augmenter. Face à cette situation, l’amélioration progressive des formes d’exploitation agricole constitue une alternative complémentaire vivement incitée. De même, la rénovation de l’organisation de la filière « Produits forestiers ligneux », principalement le charbonnage demeure impérative. Il constitue la principale activité génératrice de revenu à court terme de la population. Cependant, à long terme, il contribue activement à la dégradation des ressources naturelles en l’occurrence les formations secondaires, vestige de la forêt naturelle. Il s’agit ainsi, de promouvoir les cultures vivrières et les cultures de rente visant le marché d’une part, et d’apporter des améliorations au niveau des techniques d’exploitation des ressources forestières en vue d’un rendement optimum d’autre part.

Effects of Prolyl Hydroxylase Inhibitor L-mimosine on Dental Pulp in the Presence of Advanced Glycation End Products

INTRODUCTION Proangiogenic prolyl hydroxylase (PHD) inhibitors represent a novel approach to stimulate tissue regeneration. Diabetes mellitus involves the accumulation of advanced glycation end products (AGEs). Here we evaluated the impact of AGEs on the response of human pulp tissue to the PHD inhibitor L-mimosine (L-MIM) in monolayer cultures of dental pulp-derived cells (DPCs) and tooth slice organ cultures. METHODS In monolayer cultures, DPCs were incubated with L-MIM and AGEs. Viability was assessed based on formazan formation, live-dead staining, annexin V/propidium iodide, and trypan blue exclusion assay. Vascular endothelial growth factor (VEGF), interleukin (IL)-6, and IL-8 production was evaluated by quantitative polymerase chain reaction and immunoassays. Furthermore, expression levels of odontoblast markers were assessed, and alizarin red staining was performed. Tooth slice organ cultures were performed, and VEGF, IL-6, and IL8 levels in their supernatants were measured by immunoassays. Pulp tissue vitality and morphology were assessed by MTT assay and histology. RESULTS In monolayer cultures of DPCs, L-MIM at nontoxic concentrations increased the production of VEGF and IL-8 in the presence of AGEs. Stimulation with L-MIM decreased alkaline phosphatase levels and matrix mineralization also in the presence of AGEs, whereas no significant changes in dentin matrix protein 1 and dentin sialophosphoprotein expression were observed. In tooth slice organ cultures, L-MIM increased VEGF but not IL-6 and IL-8 production in the presence of AGEs. The pulp tissue was vital, and no signs of apoptosis or necrosis were observed. CONCLUSIONS Overall, in the presence of AGEs, L-MIM increases the proangiogenic capacity, but decreases alkaline phosphatase expression and matrix mineralization.