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)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 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 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

Physiopathologie des maladies auto-inflammatoires d’expression cutanée : Aspects moléculaires et cellulaires

-Les maladies auto-inflammatoires (MAIs) monogéniques sont des maladies rares qui se caractérisent par des accès fébriles récurrents spontanément résolutifs accompagnés d’une inflammation systémique. L’objectif de ce travail était d’identifier de nouveaux marqueurs diagnostiques de MAIs et d’approfondir les connaissances physiopathologiques de ces maladies.Le premier volet concernait l’étude des mutations germinales et somatiques en mosaïque de NLRP3, gène déjà impliqué dans les MAIs. Une réinterprétation de toutes les mutations rapportées de NLRP3 chez des patients présentant une MAI ainsi qu’une étude approfondie de cinq nouveaux patients, ont permis de caractériser les spécificités des mutations en mosaïques par rapport aux mutations germinales et de préciser le cadre phénotypique de ce syndrome. Le second volet concernait l’identification d’un nouveau gène de MAI d’expression cutanée. Une étude génétique a été réalisée au sein d’une grande famille comprenant plusieurs sujets atteints d’urticaire chronique et a permis d’identifier un nouveau gène de MAI. Des tests fonctionnels ont permis de mettre en évidence une distribution anormale de la protéine mutée au niveau du cytoplasme de la cellule par rapport à la protéine sauvage. Une étude par protéomique a permis d’identifier plusieurs partenaires protéiques dont certains sont impliqués dans l’immunité innée.Au total, ce travail a permis une meilleure connaissance de la physiopathologie des MAIs d’expression cutanée avec la caractérisation de mutations en mosaïque d’un gène déjà impliqué, et l’identification d’un nouveau gène de MAI, marqueur diagnostique particulièrement utile dans ce groupe d’affection

Pathophysiology of auto-inflammatory diseases with skin manifestations : cellular and molecular approaches

Les maladies auto-inflammatoires (MAIs) monogéniques sont des maladies rares qui se caractérisent par des accès fébriles récurrents spontanément résolutifs accompagnés d’une inflammation systémique. L’objectif de ce travail était d’identifier de nouveaux marqueurs diagnostiques de MAIs et d’approfondir les connaissances physiopathologiques de ces maladies. Le premier volet concernait l’étude des mutations germinales et somatiques en mosaïque de NLRP3, gène déjà impliqué dans les MAIs. Une réinterprétation de toutes les mutations rapportées de NLRP3 chez des patients présentant une MAI ainsi qu’une étude approfondie de cinq nouveaux patients, ont permis de caractériser les spécificités des mutations en mosaïques par rapport aux mutations germinales et de préciser le cadre phénotypique de ce syndrome. Le second volet concernait l’identification d’un nouveau gène de MAI d’expression cutanée. Une étude génétique a été réalisée au sein d’une grande famille comprenant plusieurs sujets atteints d’urticaire chronique et a permis d’identifier un nouveau gène de MAI. Des tests fonctionnels ont permis de mettre en évidence une distribution anormale de la protéine mutée au niveau du cytoplasme de la cellule par rapport à la protéine sauvage. Une étude par protéomique a permis d’identifier plusieurs partenaires protéiques dont certains sont impliqués dans l’immunité innée. Au total, ce travail a permis une meilleure connaissance de la physiopathologie des MAIs d’expression cutanée avec la caractérisation de mutations en mosaïque d’un gène déjà impliqué, et l’identification d’un nouveau gène de MAI, marqueur diagnostique particulièrement utile dans ce groupe d’affections.Monogenic auto-inflammatory diseases (AIDs) are rare diseases characterized by recurrent fevers associated with systemic inflammation. The aim of this work was to identify new diagnostic markers of AIDs and to expand the physiopathological knowledge of these diseases. The first part of this work concerned the study of germline and somatic mosaic mutations of NLRP3, a gene already involved in AIDs. A re-assessment of all the reported NLRP3 mutations in AID patients as well as an in-depth study of five new patients allowed characterizing the specificities of mosaic mutations compared to germline mutations. The second part of this work concerned the identification of a new gene of AID. A genetic approach was conducted in a large family comprising several subjects with chronic urticaria and identified a novel AID gene. Functional assays detected abnormal distribution of the mutated protein in the cytoplasm of the cell, relative to the wild-type protein. A proteomic study associated with an immunoprecipitation of the newly identified protein was performed and identified several protein interactors. Among them, some of which are implicated in innate immunity. This work allowed to better understanding the physiopathology AIDs of skin expression, with the characterization of mosaic mutations of a gene already involved, and the identification of a new AID gene, a diagnostic marker particularly useful in this group of affections

PID du nourrisson et de l’enfant : apport de la génétique dans la prise en charge thérapeutique.

National audienc

Absence of NLRP3 somatic mutations and VEXAS-related UBA1 mutations in a large cohort of patients with Schnitzler syndrome

International audienceNo abstract availabl

Questions about Residual Cell Viability in Cryopreserved Human Amniotic Membrane and Its Impact on Clinical Applications

We questioned the relevance of evaluating residual cell viability in human amniotic membrane (hAM) after its cryopreservation since cell survival is controversial and its ability to act as a matrix (including the presence of growth factors and cytokines) appears to be most important for tissue regeneration purposes. We also discussed the usefulness of osteodifferentiating amniotic cells in whole hAM for bone repair applications. We have evidence that determining residual cell viability after cryopreservation and hAM osteodifferentiation is not justified

Necroptosis study in an epithelial in vitro model expressing surfactant protein A1

International audienc

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

WT SP-A restores abnormal oligomerization and secretion of mutant SFTPA1 and SFTPA2

International audienc