RESUMO
BACKGROUND: Neutrophils are key players in the innate immune system, actively migrating to sites of inflammation in the highly energetic process of chemotaxis. In this study, we focus on the role of acyl-CoA: diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the synthesis of triglycerides, the major form of stored energy, in neutrophil chemotaxis. METHODS AND RESULTS: Using a mouse model of psoriasis, we show that DGAT1-deficiency reduces energy-demanding neutrophil infiltration to the site of inflammation, but this inhibition is not caused by decreased glycolysis and reduced ATP production by neutrophils lacking DGAT1. Flow cytometry and immunohistochemistry analysis demonstrate that DGAT1 also does not influence lipid accumulation in lipid droplets during inflammation. Interestingly, as has been shown previously, a lack of DGAT1 leads to an increase in the concentration of retinoic acid, and here, using real-time PCR and publicly-available next-generation RNA sequencing datasets, we show the upregulation of retinoic acid-responsive genes in Dgat1KO neutrophils. Furthermore, supplementation of WT neutrophils with exogenous retinoic acid mimics DGAT1-deficiency in the inhibition of neutrophil chemotaxis in in vitro transwell assay. CONCLUSIONS: These results suggest that impaired skin infiltration by neutrophils in Dgat1KO mice is a result of the inhibitory action of an increased concentration of retinoic acid, rather than impaired lipid metabolism in DGAT1-deficient mice.
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Psoriasis, which involves mast cells, is a chronic inflammatory skin disorder whose pathophysiology is still not fully understood. We investigated the role of secretory leukocyte protease inhibitor (SLPI), a potential inhibitor of mastocyte serine proteases, on mast cell-dependent processes of relevance to the skin barrier defense in psoriasis. Here, we demonstrate that the dermal mast cells of patients with psoriasis express SLPI but not those of healthy donors. Moreover, SLPI transcripts were found to be markedly upregulated in murine mast cells by mediators derived from psoriasis skin explant cultures. Using mast cells from SLPI-deficient mice and their SLPI+ wild-type controls, we show that SLPI inhibits the activity of serine protease chymase in mastocytes. SLPI was also found to enhance the degranulation of mast cells activated via anti-IgE Abs but not Mrgprb2 ligands. Finally, we demonstrate that the expression and function of Mrgprb2 in mast cells are suppressed by a normal and, to a larger extent, psoriatic skin environment. Together, these findings reveal mechanisms underlying FcεRI- and Mrgprb2-dependent mast cell function that have not been described previously.
Assuntos
Psoríase , Inibidor Secretado de Peptidases Leucocitárias , Animais , Camundongos , Inibidor Secretado de Peptidases Leucocitárias/genética , Inibidor Secretado de Peptidases Leucocitárias/metabolismo , Mastócitos/metabolismo , Proteínas Secretadas Inibidoras de Proteinases/metabolismo , Psoríase/metabolismo , PeleRESUMO
BACKGROUND: Chemerin is a chemoattractant protein with adipokine and antimicrobial properties encoded by the retinoic acid receptor responder 2 (RARRES2) gene. Chemerin bioactivity largely depends on carboxyl-terminal proteolytic processing that generates chemerin isoforms with different chemotactic, regulatory, and antimicrobial potentials. While these mechanisms are relatively well known, the role of alternative splicing in generating isoform diversity remains obscure. METHODS AND RESULTS: Using rapid amplification of cDNA ends (RACE) PCR, we determined RARRES2 transcript variants present in mouse and human tissues and identified novel transcript variant 4 of mouse Rarres2 encoding mChem153K. Moreover, analyses of real-time quantitative PCR (RT-qPCR) and publicly-available next-generation RNA sequencing (RNA-seq) datasets showed that different alternatively spliced variants of mouse Rarres2 are present in mouse tissues and their expression patterns were unaffected by inflammatory and infectious stimuli except brown adipose tissue. However, only one transcript variant of human RARRES2 was present in liver and adipose tissue. CONCLUSION: Our findings indicate a limited role for alternative splicing in generating chemerin isoform diversity under all tested conditions.
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Processamento Alternativo , Quimiocinas , Humanos , Animais , Camundongos , Quimiocinas/genética , Quimiocinas/metabolismo , Processamento Alternativo/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Adipocinas/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMO
Skin is the largest, environmentally exposed (barrier) organ, capable of integrating various signals into effective defensive responses. The functional significance of interactions among the epidermis and the immune and nervous systems in regulating and maintaining skin barrier function is only now becoming recognized in relation to skin pathophysiology. This review focuses on newly described pathways that involve soluble mediator-mediated crosstalk between these compartments. Dysregulation of these connections can lead to chronic inflammatory diseases and/or pathologic conditions associated with chronic pain or itch.
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Epiderme , Pele , Humanos , Epiderme/patologia , Prurido/metabolismo , Células Epidérmicas/metabolismo , Sistema Nervoso/metabolismoRESUMO
Chemerin is a chemoattractant protein with adipokine properties encoded by the retinoic acid receptor responder 2 (RARRES2) gene. It has gained more attention in the past few years due to its multilevel impact on metabolism and immune responses. However, mechanisms controlling the constitutive and regulated expression of RARRES2 in a variety of cell types remain obscure. To our knowledge, this report is the first to show that DNA methylation plays an important role in the cell-specific expression of RARRES2 in adipocytes, hepatocytes, and B lymphocytes. Using luciferase reporter assays, we determined the proximal fragment of the RARRES2 gene promoter, located from - 252 to + 258 bp, to be a key regulator of transcription. Moreover, we showed that chemerin expression is regulated in murine adipocytes by acute-phase cytokines, interleukin 1ß and oncostatin M. In contrast with adipocytes, these cytokines exerted a weak, if any, response in mouse hepatocytes, suggesting that the effects of IL-1ß and OSM on chemerin expression is specific to fat tissue. Together, our findings highlight previously uncharacterized mediators and mechanisms that control chemerin expression.
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Quimiocinas/metabolismo , Metilação de DNA , Regulação da Expressão Gênica/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Interleucina-1beta/farmacologia , Oncostatina M/farmacologia , Regiões Promotoras Genéticas , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Quimiocinas/genética , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Next-generation sequencing (NGS) technologies together with an improved access to compute performance led to a cost-effective genome sequencing over the past several years. This allowed researchers to fully unleash the potential of genomic and metagenomic analyses to better elucidate two-way interactions between host cells and microbiome, both in steady-state and in pathological conditions. Experimental research involving metagenomics shows that skin resident microbes can influence the cutaneous pathophysiology. Here, we review metagenome approaches to study microbiota at this barrier site. We also describe the consequences of changes in the skin microbiota burden and composition, mostly revealed by these technologies, in the development of common inflammatory skin diseases.
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Microbiota , Dermatopatias , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Metagenoma , Metagenômica , Microbiota/genéticaRESUMO
The skin is the largest and the most exposed organ in the body and its defense is regulated at several anatomical levels. Here, we explore how skin layers, including the epidermis, dermis, adipose tissue, and skin appendages, as well as cutaneous microbiota, contribute to the function of skin antimicrobial defense. We highlight recent studies that reveal the differential and complementary responses of skin layers to bacterial, viral, and fungal infection. In particular, we focus on key soluble mediators in the layered skin defense, such as antimicrobial peptides, as well as on lipid antimicrobials, cytokines, chemokines, and barrier-maintaining molecules. We include our own evaluative analyses of transcriptomic datasets of human skin to map the involvement of antimicrobial peptides in skin protection under both steady state and infectious conditions. Furthermore, we explore the versatility of the mechanisms underlying skin defense by highlighting the role of the immune and nervous systems in their interaction with cutaneous microbes, and by illustrating the multifunctionality of selected antimicrobial peptides in skin protection.
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Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/imunologia , Queratinócitos/imunologia , Pele/imunologia , Anti-Infecciosos , Quimiocinas/imunologia , Citocinas/imunologia , Perfilação da Expressão Gênica , Humanos , Queratinócitos/microbiologia , Microbiota , Pele/microbiologiaRESUMO
The human ortholog MRGPRX2 and the mice ortholog, Mrgprb2 are activated by basic secretagogues and neurokinins. A number of commonly used small-molecule drugs (e.g., neuromuscular blocking agents, fluoroquinolones, vancomycin) have been recently shown to activate these receptors under in vitro experimental conditions, what results in mast cell degranulation. The above drugs are also known to cause IgE-mediated anaphylactic reactions in allergic patients. The new findings on mechanisms of drug-induced mast cell degranulation may modify the current management of drug hypersensitivity reactions. Clinical interpretation of mild drug-provoked hypersensitivity reactions, interpretation of skin test with a drug of interest or further recommendations for patients suspected of drug allergy are likely to be reconsidered. In the paper we discussed future directions in research on identification and differentiation of MRGPRX2-mediated and IgE-dependent mast cell degranulation in patients presenting clinical features of drug-induced hypersensitivity reactions.