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Sci Rep ; 9(1): 10878, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31350436


As a first host barrier, the skin is constantly exposed to environmental insults that perturb its integrity. Tight regulation of skin homeostasis is largely controlled by the aryl hydrocarbon receptor (AhR). Here, we demonstrate that Henna and its major pigment, the naphthoquinone Lawsone activate AhR, both in vitro and in vivo. In human keratinocytes and epidermis equivalents, Lawsone exposure enhances the production of late epidermal proteins, impacts keratinocyte differentiation and proliferation, and regulates skin inflammation. To determine the potential use of Lawsone for therapeutic application, we harnessed human, murine and zebrafish models. In skin regeneration models, Lawsone interferes with physiological tissue regeneration and inhibits wound healing. Conversely, in a human acute dermatitis model, topical application of a Lawsone-containing cream ameliorates skin irritation. Altogether, our study reveals how a widely used natural plant pigment is sensed by the host receptor AhR, and how the physiopathological context determines beneficial and detrimental outcomes.

EMBO Rep ; 20(4)2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30872316


Cyclic dinucleotides (CDNs) are important second messenger molecules in prokaryotes and eukaryotes. Within host cells, cytosolic CDNs are detected by STING and alert the host by activating innate immunity characterized by type I interferon (IFN) responses. Extracellular bacteria and dying cells can release CDNs, but sensing of extracellular CDNs (eCDNs) by mammalian cells remains elusive. Here, we report that endocytosis facilitates internalization of eCDNs. The DNA sensor cGAS facilitates sensing of endocytosed CDNs, their perinuclear accumulation, and subsequent STING-dependent release of type I IFN Internalized CDNs bind cGAS directly, leading to its dimerization, and the formation of a cGAS/STING complex, which may activate downstream signaling. Thus, eCDNs comprise microbe- and danger-associated molecular patterns that contribute to host-microbe crosstalk during health and disease.

Sci Rep ; 8(1): 1520, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-29367626


Mycobacterium tuberculosis (Mtb) is a life-threatening pathogen in humans. Bacterial infection of macrophages usually triggers strong innate immune mechanisms, including IL-1 cytokine secretion. The newer member of the IL-1 family, IL-36, was recently shown to be involved in cellular defense against Mtb. To unveil the underlying mechanism of IL-36 induced antibacterial activity, we analyzed its role in the regulation of cholesterol metabolism, together with the involvement of Liver X Receptor (LXR) in this process. We report that, in Mtb-infected macrophages, IL-36 signaling modulates cholesterol biosynthesis and efflux via LXR. Moreover, IL-36 induces the expression of cholesterol-converting enzymes and the accumulation of LXR ligands, such as oxysterols. Ultimately, both IL-36 and LXR signaling play a role in the regulation of antimicrobial peptides expression and in Mtb growth restriction. These data provide novel evidence for the importance of IL-36 and cholesterol metabolism mediated by LXR in cellular host defense against Mtb.

J Infect Dis ; 214(3): 464-74, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27389350


Tuberculosis remains a major killer worldwide, not the least because of our incomplete knowledge of protective and pathogenic immune mechanism. The roles of the interleukin 1 (IL-1) and interleukin 18 pathways in host defense are well established, as are their regulation through the inflammasome complex. In contrast, the regulation of interleukin 36γ (IL-36γ), a recently described member of the IL-1 family, and its immunological relevance in host defense remain largely unknown. Here we show that Mycobacterium tuberculosis infection of macrophages induces IL-36γ production in a 2-stage-regulated fashion. In the first stage, microbial ligands trigger host Toll-like receptor and MyD88-dependent pathways, leading to IL-36γ secretion. In the second stage, endogenous IL-1ß and interleukin 18 further amplify IL-36γ synthesis. The relevance of this cytokine in the control of M. tuberculosis is demonstrated by IL-36γ-induced antimicrobial peptides and IL-36 receptor-dependent restriction of M. tuberculosis growth. Thus, we provide first insight into the induction and regulation of the proinflammatory cytokine IL-36γ during tuberculosis.

Interleucina-1/metabolismo , Mycobacterium tuberculosis/imunologia , Tuberculose/imunologia , Animais , Linhagem Celular , Humanos , Interleucina-1/deficiência , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos Endogâmicos C57BL , Camundongos Knockout
Nature ; 512(7515): 387-92, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-25119038


The aryl hydrocarbon receptor (AhR) is a highly conserved ligand-dependent transcription factor that senses environmental toxins and endogenous ligands, thereby inducing detoxifying enzymes and modulating immune cell differentiation and responses. We hypothesized that AhR evolved to sense not only environmental pollutants but also microbial insults. We characterized bacterial pigmented virulence factors, namely the phenazines from Pseudomonas aeruginosa and the naphthoquinone phthiocol from Mycobacterium tuberculosis, as ligands of AhR. Upon ligand binding, AhR activation leads to virulence factor degradation and regulated cytokine and chemokine production. The relevance of AhR to host defence is underlined by heightened susceptibility of AhR-deficient mice to both P. aeruginosa and M. tuberculosis. Thus, we demonstrate that AhR senses distinct bacterial virulence factors and controls antibacterial responses, supporting a previously unidentified role for AhR as an intracellular pattern recognition receptor, and identify bacterial pigments as a new class of pathogen-associated molecular patterns.

Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Mycobacterium tuberculosis/imunologia , Pigmentos Biológicos/metabolismo , Pseudomonas aeruginosa/imunologia , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores de Reconhecimento de Padrão/metabolismo , Animais , Antibacterianos/metabolismo , Células da Medula Óssea/citologia , Citocinas/imunologia , Citocinas/metabolismo , Retroalimentação Fisiológica , Humanos , Ligantes , Ativação de Macrófagos , Camundongos , Mycobacterium tuberculosis/crescimento & desenvolvimento , Mycobacterium tuberculosis/metabolismo , Fenazinas/metabolismo , Pigmentos Biológicos/química , Infecções por Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Piocianina/metabolismo , Fatores de Virulência/química , Fatores de Virulência/metabolismo