A Diet Containing Soybean Oil Heated for Three Hours Increases Adipose Tissue Weight but Decreases Body Weight in C57BL/6 J Mice

Background: Our previous work showed that dietary oxidized linoleic acid given, as a single fatty acid, to LDL receptor knockout mice decreased weight gain as compared to control mice. Other studies have also reported that animals fed oils heated for 24 h or greater showed reduced weight gain. These observations, while important, have limited significance since fried foods in the typical human diet do not contain the extreme levels of oxidized lipids used in these studies. The main goal of this study was to investigate the effects of a diet containing soybean oil heated for 3 h on weight gain and fat pad mass in mice. Additionally, because PPARγ and UCP-1 mediate adipocyte differentiation and thermogenesis, respectively, the effect of this diet on these proteins was also examined. Findings: Four to six week old male C57BL/6 J mice were randomly divided into three groups and given either a low fat diet with heated soybean oil (HSO) or unheated soybean oil (USO) or pair fed for 16 weeks. Weight and food intake were monitored and fat pads were harvested upon the study’s termination. Mice consuming the HSO diet had significantly increased fat pad mass but gained less weight as compared to mice in the USO group despite a similar caloric intake and similar levels of PPARγ and UCP1. Conclusion: This is the first study to show that a diet containing soybean oil heated for a short time increases fat mass despite a decreased weight gain in C57BL/6 J mice. The subsequent metabolic consequences of this increased fat mass merits further investigation

Inflammasome biology, molecular pathology and therapeutic implications

Inflammasomes are intracellular multiprotein signaling complexes, mainly present in myeloid cells. They commonly assemble around a cytoplasmic receptor of the nucleotide-binding leucine-rich repeat containing receptor (NLR) family, although other cytoplasmic receptors like pyrin have been shown to forminflammasomes. The nucleation of the multiprotein scaffolding platform occurs upon detection of a microbial, a danger or a homeostasis pattern by the receptor that will, most commonly, associate with the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD) through homotypic domain interactions resulting in recruitment of procaspase-1. This will lead to the autoproteolytic activation of caspase-1, which regulates the secretion of proinflammatory IL1β and IL18 cytokines and pyroptosis, a caspase-1-mediated form of cell death. Pyroptosis occurs through cleavage of Gasdermin D, a membrane pore forming protein. Recently, non-canonical inflammasomes have been described, which directly sense intracellular pathogens through caspase-4 and -5 in humans, leading to pyroptosis. Inflammasomes are important in host defense; however, a deregulated activity is associated with a number of inflammatory, immune and metabolic disorders. Furthermore, mutations in inflammasome receptor coding genes are causal for an increasing number of rare autoinflammatory diseases. Biotherapies targeting the products of inflammasome activation aswell as molecules that directly or indirectly inhibit inflammasome nucleation and activation are promising therapeutic areas. This review discusses recent advances in inflammasome biology, the molecular pathology of several inflammasomes, and current therapeutic approaches in autoinflammatory diseases and in selected common multifactorial inflammasome-mediated disorders

Molecular and functional characterization of polymorphisms in the secreted phospholipase A2 group X gene: relevance to coronary artery disease

Among secreted phospholipases A2 (sPLA2s), human group X sPLA2 (hGX sPLA2) is emerging as a novel attractive therapeutic target due to its implication in inflammatory diseases. To elucidate whether hGX sPLA2 plays a causative role in coronary artery disease (CAD), we screened the human PLA2G10 gene to identify polymorphisms and possible associations with CAD end-points in a prospective study, AtheroGene. We identified eight polymorphisms, among which, one non-synonymous polymorphism R38C in the propeptide region of the sPLA2. The T-512C polymorphism located in the 5′ untranslated region was associated with a decreased risk of recurrent cardiovascular events during follow-up. The functional analysis of the R38C polymorphism showed that it leads to a profound change in expression and activity of hGX sPLA2, although there was no detectable impact on CAD risk. Due to the potential role of hGX sPLA2 in inflammatory processes, these polymorphisms should be investigated in other inflammatory diseases

Inflammasome in atherosclerosis

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Oxidative inactivation of paraoxonase - implications in diabetes mellitus and atherosclerosis

Human serum paraoxonase (PON1) has been implicated to play an important role in cardiovascular disease and diabetes. Studies in the literature indicate that PON1 has two different enzyme activities, i.e., esterase and hydroperoxide reducing activities. The objective of this study was to establish the importance of these two activities and to distinguish between them. As the addition of copper immediately inactivated the enzyme, we used auto-oxidation as the model system. Auto-oxidation of HDL resulted in more than 80% reduction of the esterolytic activity, which was protected by antioxidants, Vitamin E (50%) and PDTC (95%) and completely by 1 M glucose. In contrast, the hydroperoxide reducing activity, using unesterified hydroperoxides remained unaffected with time. We also used pNPHPODE (novel substrate) to establish that hydrolysis might be a prerequisite for the enzyme to act on the esterified hydroperoxide. The results indicated that the hydrolysis of the substrate was inhibited under oxidizing conditions with no reduction of the hydroperoxide. Overall, our findings suggest that protecting the esterolytic activity of PON1 by antioxidants might be important in preserving its action on phospholipid peroxides and a concerted reaction involving the esterolytic and hydroperoxide reducing activities might be suggested for the action of PON

Inflammasomes et épidermolyse bulleuse

National audienceResults Conclusion In this study, we demonstrated that keratinocytes derived from JEB and EBS patients exhibit increased expression of inflammasome components compared to NHEK suggesting a role of inflammasome(s) in EB pathogenesis. Our data highlight the importance of adhesion of the different skin layers to ensure keratinocyte homeostasis. As the dysregulation of inflammasome sensors leads to the excessive production of pro-inflammatory cytokines, it could contribute to the chronic inflammation observed in EB. Further studies on the type of inflammasome(s) implicated in EB and targeted therapeutic interventions to modulate inflammasome activation may hold promise for the development of anti-inflammatory therapies in EB.L'épidermolyse bulleuse (EB) regroupe un groupe de maladies génétiques rares du tissu conjonctif caractérisées par une fragilité de la peau et la formation de phlyctènes en raison de mutations dans les gènes codant pour des protéines de la membrane basale ou des protéines modulant l'organisation de la membrane basale. Malgré la variabilité phénotypique, toutes les formes d'EB présentent des défauts de réparation et de cicatrisation des tissus à la suite de traumatismes mineurs entraînant une inflammation locale. Le rôle des cytokines dans l'orchestration de la réparation et de l'intégrité des tissus dans l'EB a été peu étudié. Les infammasomes sont des complexes multiprotéiques qui contrôlent l'activation et la libération de cytokines pro-inflammatoires, à savoir l'interleukine-1β (IL-1β) et l'interleukine-18 (IL-18), par l'intermédiaire de la caspase-1. Notre objectif était d'étudier l'expression des composants de l'inflammasome et la sécrétion de cytokines dans les kératinocytes de patients atteints d'EB et de contrôles.Des kératinocytes primaires ont été dérivés de biopsies de personnes atteintes de différents types d'EB, dont l'épidermolyse bulleuse jonctionnelle (JEB) (N=4) et l'épidermolyse bulleuse simplex (EBS) (N=4). Les kératinocytes épidermiques humains normaux (NHEK) ont été utilisés comme contrôles. L'expression des principaux capteurs de l'inflammasome (NOD-like Receptors (NLRs)), des membres de la famille des caspases et des cytokines a été déterminée. En parallèle, la sécrétion de cytokines a été mesurée par ELISA.Nous avons observé des niveaux élevés d’expression de NLRP1, NLRP3, NLRP6, MEFV, NOD2, NLRC4, NLRP4, NLRP10 et NLRP12 dans les kératinocytes dérivés de patients JEB par rapport aux NHEK. L'expression de NLRP6, MEFV, AIM2 et NLRC4 était plus élevée chez les patients EBS que chez les NHEK. L'expression de CASP1 et CASP4 était plus élevée chez les patients JEB et EBS que chez les NHEK, mais était de niveau comparable chez les patients JEB et EBS. L'expression des gènes IL-1B et IL-18 était significativement plus élevée chez les patients JEB que chez les NHEK. La sécrétion d'IL-1β était significativement plus élevée chez les patients JEB que chez les EBS ou les contrôles. De façon inattendue, la sécrétion d'IL-18 était inférieure à la limite de détection dans tous les groupes.Nos résultats ont démontré que les kératinocytes dérivés des patients JEB et EBS présentent une expression accrue des composants de l'inflammasome par rapport aux NHEK, ce qui suggère un rôle de l'inflammasome dans l'EB. Le dérèglement des senseurs de l'inflammasome, qui entraîne une production excessive de cytokines pro-inflammatoires, pourrait donc contribuer à l'inflammation chronique observée dans l'EB. Des études complémentaires sur le type d'inflammasome(s) impliqué(s) dans l'EB et l’utilisation ciblée de modulateurs de l’activation des inflammasomes pourraient être prometteuses pour le développement de traitements anti-inflammatoires pour l'EB

Photoaging and skin cancer: Is the inflammasome the missing link?

International audiencePhotoaging and epithelial skin tumorigenesis are complex processes triggered mainly by UV radiation from chronic sun exposure. This leads to DNA damage and reactive oxygen species (ROS) production, which initiate an inflammatory response that alters cell structure and function. Changes in cell homeostasis and ROS production activate intracellular multiprotein platforms called inflammasomes. Inflammasomes nucleate around cytoplasmic receptors mainly of the NLR (nucleotide-binding domain and leucine-rich repeat) family and regulate caspase-1-dependant secretion of pro-inflammatory interleukin (IL)1β and IL18 cytokines, and an inflammatory form of death named pyroptosis. NLRP1 inflammasomes have taken centre stage in skin biology, as mutations in NLRP1 underlie the genetic etiology of dermatological diseases and increase the susceptibility to skin cancer. Targeting inflammasome(s) might be an important approach to improve skin inflammation, photoaging and reduce the risk of epithelial skin tumorigenesis. In this context, we discuss the potential implication of NLRP1 and NLRP3 inflammasome

A thioredoxin-mimetic peptide exerts potent anti-inflammatory, antioxidant, and atheroprotective effects in ApoE2.Ki mice fed high fat diet

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The proinflammatory mediator Platelet Activating Factor is an effective substrate for human group X secreted phospholipase A2.

Platelet Activating Factor (PAF) is a potent mediator of inflammation whose biological activity depends on the acetyl group esterified at the sn-2 position of the molecule. PAF-acetylhydrolase (PAF-AH), a secreted calcium-independent phospholipase A(2), is known to inactivate PAF by formation of lyso-PAF and acetate. However, PAF-AH deficient patients are not susceptible to the biological effects of inhaled PAF in airway inflammation, suggesting that other enzymes may regulate extracellular levels of PAF. We therefore examined the hydrolytic activity of the recently described human group X secreted phospholipase A(2) (hGX sPLA(2)) towards PAF. Among different sPLA(2)s, hGX sPLA(2) has the highest affinity towards phosphatidylcholine (PC), the major phospholipid of cellular membranes and plasma lipoproteins. Our results show that unlike group IIA, group V, and the pancreatic group IB sPLA(2), recombinant hGX sPLA(2) can efficiently hydrolyze PAF. The hydrolysis of PAF by hGX sPLA(2) rises abruptly when the concentration of PAF passes through its critical micelle concentration suggesting that the enzyme undergoes interfacial binding and activation to PAF. In conclusion, our study shows that hGX sPLA(2) may be a novel player in PAF regulation during inflammatory processes