29 research outputs found
Photoaging and skin cancer: Is the inflammasome the missing link?
Photoaging 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)1ÎČ 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 inflammasomes
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 IL1ÎČ 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
Bases moléculaires et cellulaires des maladies auto-inflammatoires monogéniques et des amyloses AA
The serum amyloid A (SAA) family includes the acute phase reactants SAA1 and SAA2 induced during systemic inflammation. SAA are mainly synthesized by the liver but extra-hepatic sources exist. Persistent high circulating levels of SAA may lead to amyloid A (AA) amyloidosis due to formation of insoluble AA protein aggregates. AA amyloidosis appears mainly as a long-term complication of auto-inflammatory diseases (like familial Mediterranean fever, FMF) or of common diseases with an inflammatory component (like obesity or gout). No molecular etiology for AA amyloidosis has been identified so far; however, a specific genotype at the SAA1 locus has been associated with AA amyloidosis in FMF patients. FMF is considered as an autosomal recessive disease due to bi-allelic mutations in the MEFV gene (encoding the pyrin protein), but the significant number of patients with a clinical diagnosis of FMF carrying a single mutated MEFV allele challenges the recessive transmission model of FMF.This thesis studied: (i) if monocytes/macrophages can express SAA genes; (ii) the molecular bases of AA amyloidosis (primary and secondary amyloidosis in the context of obesity and gout); (iii) the molecular mechanisms underlying FMF in patients carrying a single mutated MEFV allele.La famille de protĂ©ines serum amyloid A (SAA) inclut les protĂ©ines de phase aigue SAA1 et SAA2, induites par lâinflammation. Les protĂ©ines SAA sont surtout synthĂ©tisĂ©es par le foie mais dâautres sources extra-hĂ©patiques existent. Des taux Ă©levĂ©s de SAA circulantes peuvent mener Ă lâamylose amyloid A (AA), due Ă la formation dâagrĂ©gats insolubles de protĂ©ines AA. Celle-ci survient principalement comme une complication Ă long-terme de maladies auto-inflammatoires (comme la fiĂšvre MĂ©diterranĂ©enne familiale, FMF) ou de maladies communes avec une composante inflammatoire (comme lâobĂ©sitĂ© ou la goutte). Lâamylose AA nâa pas dâĂ©tiologie molĂ©culaire identifiĂ©e jusquâĂ prĂ©sent; cependant, un certain gĂ©notype au locus SAA1 a Ă©tĂ© associĂ© avec lâamylose AA chez des patients FMF. La FMF est considĂ©rĂ©e comme une maladie Ă transmission autosomique rĂ©cessive due Ă des mutations bi-allĂ©liques du gĂšne MEFV (codant la protĂ©ine pyrine), mais le nombre Ă©levĂ© de patients au diagnostic clinique de FMF, porteurs dâun seul allĂšle MEFV mutĂ©, challenge le modĂšle de transmission rĂ©cessive de la FMF.Cette thĂšse visait Ă Ă©tudier: (i) lâexpression des gĂšnes SAA par les monocytes/macrophages; (ii) les bases molĂ©culaires de lâamylose AA (primaire et secondaire dans le contexte de lâobĂ©sitĂ© et de la goutte); (iii) les mĂ©canismes molĂ©culaires sous-jacent Ă la FMF chez les patients porteurs dâun seul allĂšle MEFV mut
Bases moléculaires et cellulaires des maladies auto-inflammatoires monogéniques et des amyloses AA
La famille de protĂ©ines serum amyloid A (SAA) inclut les protĂ©ines de phase aigue SAA1 et SAA2, induites par lâinflammation. Les protĂ©ines SAA sont surtout synthĂ©tisĂ©es par le foie mais dâautres sources extra-hĂ©patiques existent. Des taux Ă©levĂ©s de SAA circulantes peuvent mener Ă lâamylose amyloid A (AA), due Ă la formation dâagrĂ©gats insolubles de protĂ©ines AA. Celle-ci survient principalement comme une complication Ă long-terme de maladies auto-inflammatoires (comme la fiĂšvre MĂ©diterranĂ©enne familiale, FMF) ou de maladies communes avec une composante inflammatoire (comme lâobĂ©sitĂ© ou la goutte). Lâamylose AA nâa pas dâĂ©tiologie molĂ©culaire identifiĂ©e jusquâĂ prĂ©sent; cependant, un certain gĂ©notype au locus SAA1 a Ă©tĂ© associĂ© avec lâamylose AA chez des patients FMF. La FMF est considĂ©rĂ©e comme une maladie Ă transmission autosomique rĂ©cessive due Ă des mutations bi-allĂ©liques du gĂšne MEFV (codant la protĂ©ine pyrine), mais le nombre Ă©levĂ© de patients au diagnostic clinique de FMF, porteurs dâun seul allĂšle MEFV mutĂ©, challenge le modĂšle de transmission rĂ©cessive de la FMF.Cette thĂšse visait Ă Ă©tudier: (i) lâexpression des gĂšnes SAA par les monocytes/macrophages; (ii) les bases molĂ©culaires de lâamylose AA (primaire et secondaire dans le contexte de lâobĂ©sitĂ© et de la goutte); (iii) les mĂ©canismes molĂ©culaires sous-jacent Ă la FMF chez les patients porteurs dâun seul allĂšle MEFV mutĂ©.The serum amyloid A (SAA) family includes the acute phase reactants SAA1 and SAA2 induced during systemic inflammation. SAA are mainly synthesized by the liver but extra-hepatic sources exist. Persistent high circulating levels of SAA may lead to amyloid A (AA) amyloidosis due to formation of insoluble AA protein aggregates. AA amyloidosis appears mainly as a long-term complication of auto-inflammatory diseases (like familial Mediterranean fever, FMF) or of common diseases with an inflammatory component (like obesity or gout). No molecular etiology for AA amyloidosis has been identified so far; however, a specific genotype at the SAA1 locus has been associated with AA amyloidosis in FMF patients. FMF is considered as an autosomal recessive disease due to bi-allelic mutations in the MEFV gene (encoding the pyrin protein), but the significant number of patients with a clinical diagnosis of FMF carrying a single mutated MEFV allele challenges the recessive transmission model of FMF. This thesis studied: (i) if monocytes/macrophages can express SAA genes; (ii) the molecular bases of AA amyloidosis (primary and secondary amyloidosis in the context of obesity and gout); (iii) the molecular mechanisms underlying FMF in patients carrying a single mutated MEFV allele
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)1ÎČ 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
Inflammasomes et Ă©pidermolyse 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'Ă©pidermolyse bulleuse (EB) regroupe un groupe de maladies gĂ©nĂ©tiques rares du tissu conjonctif caractĂ©risĂ©es par une fragilitĂ© de la peau et la formation de phlyctĂšnes en raison de mutations dans les gĂšnes codant pour des protĂ©ines de la membrane basale ou des protĂ©ines modulant l'organisation de la membrane basale. MalgrĂ© la variabilitĂ© phĂ©notypique, toutes les formes d'EB prĂ©sentent des dĂ©fauts de rĂ©paration et de cicatrisation des tissus Ă la suite de traumatismes mineurs entraĂźnant une inflammation locale. Le rĂŽle des cytokines dans l'orchestration de la rĂ©paration et de l'intĂ©gritĂ© des tissus dans l'EB a Ă©tĂ© peu Ă©tudiĂ©. Les infammasomes sont des complexes multiprotĂ©iques qui contrĂŽlent l'activation et la libĂ©ration de cytokines pro-inflammatoires, Ă savoir l'interleukine-1ÎČ (IL-1ÎČ) et l'interleukine-18 (IL-18), par l'intermĂ©diaire de la caspase-1. Notre objectif Ă©tait d'Ă©tudier l'expression des composants de l'inflammasome et la sĂ©crĂ©tion de cytokines dans les kĂ©ratinocytes de patients atteints d'EB et de contrĂŽles.Des kĂ©ratinocytes primaires ont Ă©tĂ© dĂ©rivĂ©s de biopsies de personnes atteintes de diffĂ©rents types d'EB, dont l'Ă©pidermolyse bulleuse jonctionnelle (JEB) (N=4) et l'Ă©pidermolyse bulleuse simplex (EBS) (N=4). Les kĂ©ratinocytes Ă©pidermiques humains normaux (NHEK) ont Ă©tĂ© utilisĂ©s comme contrĂŽles. L'expression des principaux capteurs de l'inflammasome (NOD-like Receptors (NLRs)), des membres de la famille des caspases et des cytokines a Ă©tĂ© dĂ©terminĂ©e. En parallĂšle, la sĂ©crĂ©tion de cytokines a Ă©tĂ© mesurĂ©e par ELISA.Nous avons observĂ© des niveaux Ă©levĂ©s dâexpression de NLRP1, NLRP3, NLRP6, MEFV, NOD2, NLRC4, NLRP4, NLRP10 et NLRP12 dans les kĂ©ratinocytes dĂ©rivĂ©s de patients JEB par rapport aux NHEK. L'expression de NLRP6, MEFV, AIM2 et NLRC4 Ă©tait plus Ă©levĂ©e chez les patients EBS que chez les NHEK. L'expression de CASP1 et CASP4 Ă©tait plus Ă©levĂ©e chez les patients JEB et EBS que chez les NHEK, mais Ă©tait de niveau comparable chez les patients JEB et EBS. L'expression des gĂšnes IL-1B et IL-18 Ă©tait significativement plus Ă©levĂ©e chez les patients JEB que chez les NHEK. La sĂ©crĂ©tion d'IL-1ÎČ Ă©tait significativement plus Ă©levĂ©e chez les patients JEB que chez les EBS ou les contrĂŽles. De façon inattendue, la sĂ©crĂ©tion d'IL-18 Ă©tait infĂ©rieure Ă la limite de dĂ©tection dans tous les groupes.Nos rĂ©sultats ont dĂ©montrĂ© que les kĂ©ratinocytes dĂ©rivĂ©s des patients JEB et EBS prĂ©sentent une expression accrue des composants de l'inflammasome par rapport aux NHEK, ce qui suggĂšre un rĂŽle de l'inflammasome dans l'EB. Le dĂ©rĂšglement des senseurs de l'inflammasome, qui entraĂźne une production excessive de cytokines pro-inflammatoires, pourrait donc contribuer Ă l'inflammation chronique observĂ©e dans l'EB. Des Ă©tudes complĂ©mentaires sur le type d'inflammasome(s) impliquĂ©(s) dans l'EB et lâutilisation ciblĂ©e de modulateurs de lâactivation des inflammasomes pourraient ĂȘtre prometteuses pour le dĂ©veloppement de traitements anti-inflammatoires pour l'EB
Inflammasome biology, molecular pathology and therapeutic implications
International audienceInflammasomes 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 form inflammasomes. 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 IL1ÎČ 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 as well 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
Expression of SAA1, SAA2 and SAA4 genes in human primary monocytes and monocyte-derived macrophages
International audienceCirculating serum amyloid A (SAA) is increased in various inflammatory conditions. The human SAA protein family comprises the acute phase SAA1/SAA2, known to activate a large set of innate and adaptive immune cells, and the constitutive SAA4. The liver synthesis of SAA1/SAA2 is well-established but there is still an open debate on extrahepatic SAA expression especially in macrophages. We aimed to investigate the ability of human primary monocytes and monocyte-derived macrophages to express SAA1, SAA2 and SAA4 at both the transcriptional and protein levels, as previous studies almost exclusively dealt with monocytic cell lines. Monocytes and derived macrophages from healthy donors were stimulated under various conditions. In parallel with SAA, pro-inflammatory IL1A, IL1B and IL6 cytokine expression was assessed. While LPS alone was non-effective, a combined LPS/dexamethasone treatment induced SAA1 and to a lesser extent SAA2 transcription in human monocytes and macrophages. In contrast, as expected, pro-inflammatory cytokine expression was strongly induced following stimulation with LPS, an effect which was dampened in the presence of dexamethasone. Furthermore, in monocytes polarized towards a pro-inflammatory M1 phenotype, SAA expression in response to LPS/dexamethasone was potentiated; a result mainly seen for SAA1. However, a major discrepancy was observed between SAA mRNA and intracellular protein levels under the experimental conditions used. Our results demonstrate that human monocytes and macrophages can express SAA genes, mainly SAA1 in response to an inflammatory environment. While SAA is considered as a member of a large cytokine network, its expression in the monocytes-macrophages in response to LPS-dexamethasone is strikingly different from that observed for classic pro-inflammatory cytokines. As monocytes-macrophages are major players in chronic inflammatory diseases, it may be hypothesized that SAA production from macrophages may contribute to the local inflammatory microenvironment, especially when macrophages are compactly organized in granulomas as in sarcoidosis
Expression des gĂšnes SAA par les monocytes et macrophages humains
National audienceLes taux des protĂ©ines serum amyloid A (SAA) sont augmentĂ©s par diverses conditions inflammatoires. Chez lâHomme, la famille de protĂ©ines SAA comporte les protĂ©ines de phase aigĂŒe SAA1/SAA2, connues pour activer de nombreuses cellules immunitaires, et la protĂ©ine constitutive SAA4. La synthĂšse hĂ©patique des protĂ©ines SAA1/SAA2 est bien Ă©tablie mais une expression extra-hĂ©patique est encore dĂ©battue, particuliĂšrement dans les macrophages. De plus, des auteurs ont mis en Ă©vidence la prĂ©sence dâARNm SAA dans des cellules spumeuses de plaques dâathĂ©romes. Nous avons Ă©tudiĂ© la capacitĂ© des monocytes et macrophages dĂ©rivĂ©s de monocytes humains Ă exprimer SAA1, SAA2 et SAA4, au niveau transcriptionnel et protĂ©ique, tandis que les Ă©tudes prĂ©cĂ©dentes ont principalement investiguĂ© des lignĂ©es monocytaires. Des monocytes et macrophages dĂ©rivĂ©s de monocytes de donneurs sains ont Ă©tĂ© traitĂ©s par diffĂ©rentes conditions. Lâexpression des cytokines pro-inflammatoires IL1A, IL1B et IL6 a Ă©tĂ© Ă©tudiĂ©e en parallĂšle de lâexpression des gĂšnes SAA. Nous avons mis en Ă©vidence lâexpression du gĂšne SAA1, et de SAA2 Ă une moindre mesure, lorsque les cellules sont simultanĂ©ment traitĂ©es par un agent pro-inflammatoire et un agent anti-inflammatoire. Lâagent pro-inflammatoire seul nâavait pas dâeffet sur lâexpression des gĂšnes SAA, bien quâil induise, comme attendu, lâexpression des cytokines pro-inflammatoires, effet amoindri par lâajout du stimulus anti-inflammatoire. De plus, la polarisation des monocytes en phĂ©notype pro-inflammatoire M1 potentialisait lâexpression des gĂšnes SAA, principalement SAA1. Nous avons cependant observĂ© un Ă©cart entre les taux dâARNm SAA et les taux intracellulaires de protĂ©ines. Nos rĂ©sultats montrent que les monocytes et macrophages humains peuvent exprimer les gĂšnes SAA, principalement SAA1, dans un environnement inflammatoire. Les monocytes et macrophages Ă©tant des acteurs majeurs de maladies inflammatoires, il est possible dâĂ©mettre lâhypothĂšse que la production de SAA par les monocytes et macrophages peut contribuer Ă la persistance dâun microenvironnement local inflammatoire et Ă la formation des plaques dâathĂ©romes
Expression des gĂšnes SAA par les monocytes et macrophages humains
National audienceLes taux des protĂ©ines serum amyloid A (SAA) sont augmentĂ©s par diverses conditions inflammatoires. Chez lâHomme, la famille de protĂ©ines SAA comporte les protĂ©ines de phase aigĂŒe SAA1/SAA2, connues pour activer de nombreuses cellules immunitaires, et la protĂ©ine constitutive SAA4. La synthĂšse hĂ©patique des protĂ©ines SAA1/SAA2 est bien Ă©tablie mais une expression extra-hĂ©patique est encore dĂ©battue, particuliĂšrement dans les macrophages. De plus, des auteurs ont mis en Ă©vidence la prĂ©sence dâARNm SAA dans des cellules spumeuses de plaques dâathĂ©romes. Nous avons Ă©tudiĂ© la capacitĂ© des monocytes et macrophages dĂ©rivĂ©s de monocytes humains Ă exprimer SAA1, SAA2 et SAA4, au niveau transcriptionnel et protĂ©ique, tandis que les Ă©tudes prĂ©cĂ©dentes ont principalement investiguĂ© des lignĂ©es monocytaires. Des monocytes et macrophages dĂ©rivĂ©s de monocytes de donneurs sains ont Ă©tĂ© traitĂ©s par diffĂ©rentes conditions. Lâexpression des cytokines pro-inflammatoires IL1A, IL1B et IL6 a Ă©tĂ© Ă©tudiĂ©e en parallĂšle de lâexpression des gĂšnes SAA. Nous avons mis en Ă©vidence lâexpression du gĂšne SAA1, et de SAA2 Ă une moindre mesure, lorsque les cellules sont simultanĂ©ment traitĂ©es par un agent pro-inflammatoire et un agent anti-inflammatoire. Lâagent pro-inflammatoire seul nâavait pas dâeffet sur lâexpression des gĂšnes SAA, bien quâil induise, comme attendu, lâexpression des cytokines pro-inflammatoires, effet amoindri par lâajout du stimulus anti-inflammatoire. De plus, la polarisation des monocytes en phĂ©notype pro-inflammatoire M1 potentialisait lâexpression des gĂšnes SAA, principalement SAA1. Nous avons cependant observĂ© un Ă©cart entre les taux dâARNm SAA et les taux intracellulaires de protĂ©ines. Nos rĂ©sultats montrent que les monocytes et macrophages humains peuvent exprimer les gĂšnes SAA, principalement SAA1, dans un environnement inflammatoire. Les monocytes et macrophages Ă©tant des acteurs majeurs de maladies inflammatoires, il est possible dâĂ©mettre lâhypothĂšse que la production de SAA par les monocytes et macrophages peut contribuer Ă la persistance dâun microenvironnement local inflammatoire et Ă la formation des plaques dâathĂ©romes