RESUMO
Medical ethics is relevant to the clinical practice of allergy and immunology regardless of the type of patient, disease state, or practice setting. When engaging in clinical care, performing research, or enacting policies on the accessibility and distribution of healthcare resources, physicians regularly make and justify decisions using the fundamental principles of medical ethics. Thus, knowledge of these principles is paramount for allergists/immunologists. To date, there has been a shortage of medical ethics research in allergy and immunology. This review describes this scarcity, highlights publication trends over time, and advocates for additional support for research and training in medical ethics with a focus on topics germane to the practice of allergy and immunology.
Assuntos
Alergia e Imunologia , Humanos , Alergia e Imunologia/ética , Ética Médica , Pesquisa Biomédica/éticaRESUMO
Glucocorticoid hormones (GC) regulate essential physiological functions including energy homeostasis, embryonic and postembryonic development, and the stress response. From the biomedical perspective, GC have garnered a tremendous amount of attention as highly potent anti-inflammatory and immunosuppressive medications indispensable in the clinic. GC signal through the GC receptor (GR), a ligand-dependent transcription factor whose structure, DNA binding, and the molecular partners that it employs to regulate transcription have been under intense investigation for decades. In particular, next-generation sequencing-based approaches have revolutionized the field by introducing a unified platform for a simultaneous genome-wide analysis of cellular activities at the level of RNA production, binding of transcription factors to DNA and RNA, and chromatin landscape and topology. Here we describe fundamental concepts of GC/GR function as established through traditional molecular and in vivo approaches and focus on the novel insights of GC biology that have emerged over the last 10 years from the rapidly expanding arsenal of system-wide genomic methodologies.
Assuntos
Genoma/genética , Glucocorticoides/genética , Glucocorticoides/metabolismo , Transdução de Sinais/fisiologia , Animais , Genômica/métodos , Humanos , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoAssuntos
Síndromes de Imunodeficiência , Quinases Associadas a Receptores de Interleucina-1 , Doenças da Imunodeficiência Primária , Humanos , Quinases Associadas a Receptores de Interleucina-1/genética , Quinases Associadas a Receptores de Interleucina-1/deficiência , Doenças da Imunodeficiência Primária/diagnóstico , Doenças da Imunodeficiência Primária/genética , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/diagnóstico , Masculino , Feminino , Mutação/genéticaRESUMO
BACKGROUND: Inflammation triggered by infection or injury is tightly controlled by glucocorticoid hormones which signal via a dedicated transcription factor, the Glucocorticoid Receptor (GR), to regulate hundreds of genes. However, the hierarchy of transcriptional responses to GR activation and the molecular basis of their oftentimes non-linear dynamics are not understood. RESULTS: We investigated early glucocorticoid-driven transcriptional events in macrophages, a cell type highly responsive to both pro- and anti-inflammatory stimuli. Using whole transcriptome analyses in resting and acutely lipopolysaccharide (LPS)-stimulated macrophages, we show that early GR target genes form dense networks with the majority of control nodes represented by transcription factors. The expression dynamics of several glucocorticoid-responsive genes are consistent with feed forward loops (FFL) and coincide with rapid GR recruitment. Notably, GR binding sites in genes encoding members of the KLF transcription factor family colocalize with KLF binding sites. Moreover, our gene expression, transcription factor binding and computational data are consistent with the existence of the GR-KLF9-KLF2 incoherent FFL. Analysis of LPS-downregulated genes revealed striking enrichment in multimerized Zn-fingers- and KRAB domain-containing proteins known to bind nucleic acids and repress transcription by propagating heterochromatin. This raises an intriguing possibility that an increase in chromatin accessibility in inflammatory macrophages results from broad downregulation of negative chromatin remodelers. CONCLUSIONS: Pro- and anti-inflammatory stimuli alter the expression of a vast array of transcription factors and chromatin remodelers. By regulating multiple transcription factors, which propagate the initial hormonal signal, GR acts as a coordinating hub in anti-inflammatory responses. As several KLFs promote the anti-inflammatory program in macrophages, we propose that GR and KLFs functionally cooperate to curb inflammation.
Assuntos
Biologia Computacional , Redes Reguladoras de Genes , Macrófagos/metabolismo , Receptores de Glucocorticoides/metabolismo , Fatores de Transcrição/metabolismo , Animais , Dexametasona/farmacologia , Regulação para Baixo/efeitos dos fármacos , Perfilação da Expressão Gênica , Redes Reguladoras de Genes/efeitos dos fármacos , Glucocorticoides/farmacologia , Cinética , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Camundongos , Modelos Biológicos , Transdução de Sinais/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacosRESUMO
Immunotherapy is a treatment approach based on the principle of incremental allergen exposure to achieve desensitization. Recently, oral immunotherapy has been introduced as a treatment of IgE-mediated food allergy. Some patients receiving oral immunotherapy for food allergy may develop eosinophilic esophagitis. Here, we summarize the literature examining this association, its treatment, and outcomes and discuss possible explanations for this clinical phenomenon. We further identify potential associations with aeroallergen sensitivity and other forms of immunotherapy including subcutaneous immunotherapy and sublingual immunotherapy. Finally, we discuss management of immunotherapy-induced eosinophilic esophagitis. Epicutaneous immunotherapy is highlighted as an area of therapeutic investigation.
Assuntos
Esofagite Eosinofílica , Hipersensibilidade Alimentar , Imunoterapia Sublingual , Humanos , Esofagite Eosinofílica/etiologia , Esofagite Eosinofílica/terapia , Dessensibilização Imunológica/efeitos adversos , Hipersensibilidade Alimentar/tratamento farmacológico , Alérgenos/uso terapêuticoRESUMO
Transcriptional regulators such as the glucocorticoid receptor (GR) recruit multiple cofactors to activate or repress transcription. Although most cofactors are intrinsically bifunctional, little is known about the molecular mechanisms dictating the specific polarity of regulation. Furthermore, chromatin modifications thought to be confined to silent loci appear in actively transcribed genes suggesting that similar enzymatic activities may mediate constitutive and transient chromatin states. GRIP1, a GR ligand-dependent coregulator of the p160 family can potentiate or inhibit transcription but the molecular contexts and mechanisms that enable GRIP1 corepressor activity are poorly understood. In a yeast 2-hybrid screen with GRIP1 repression domain (RD)-containing fragment, we repeatedly isolated the C-terminal region of a SET domain-containing protein subsequently identified as histone H4 lysine 20 trimethyltransferase, Suv4-20h1. We cloned a full-length Suv4-20h1 and dissected its interaction with GRIP1 in yeast, in vitro, and in mammalian cells. Strict nuclear localization and high salt concentration required for Suv4-20h1 extraction were consistent with its tight association with chromatin. Overexpression of Suv4-20h1 in human U2OS and A549 cells expressing integrated and endogenous GR, respectively, antagonized ligand-dependent induction of a subset of GR target genes, whereas Suv4-20h1 siRNA-mediated depletion had a reciprocal effect. Inhibition of GR transactivation required both the GRIP1 interacting region of Suv4-20h1 and its catalytic activity. Thus, Suv4-20h1 known exclusively as a factor involved in constitutive heterochromatin maintenance, actively participates in hormone-dependent transcriptional regulation affecting GR target gene expression in a promoter- and cell type-specific manner.
Assuntos
Proteínas de Transporte/metabolismo , Regulação da Expressão Gênica , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptores de Glucocorticoides/genética , Sítios de Ligação , Proteínas de Transporte/fisiologia , Linhagem Celular , Clonagem Molecular , Histona-Lisina N-Metiltransferase/fisiologia , Humanos , Proteínas do Tecido Nervoso/fisiologia , Ligação Proteica , Estrutura Terciária de Proteína , Transcrição GênicaRESUMO
Studies on macrophage gene expression have historically focused on events leading to RNA polymerase II recruitment and transcription initiation, whereas the contribution of post-initiation steps to macrophage activation remains poorly understood. Here, we report that widespread promoter-proximal RNA polymerase II pausing in resting macrophages is marked by co-localization of the negative elongation factor (NELF) complex and facilitated by PU.1. Upon inflammatory stimulation, over 60% of activated transcriptome is regulated by polymerase pause-release and a transient genome-wide NELF dissociation from chromatin, unexpectedly, independent of CDK9, a presumed NELF kinase. Genetic disruption of NELF in macrophages enhanced transcription of AP-1-encoding Fos and Jun and, consequently, AP-1 targets including Il10. Augmented expression of IL-10, a critical anti-inflammatory cytokine, in turn, attenuated production of pro-inflammatory mediators and, ultimately, macrophage-mediated inflammation in vivo. Together, these findings establish a previously unappreciated role of NELF in constraining transcription of inflammation inhibitors thereby enabling inflammatory macrophage activation.
Assuntos
Anti-Inflamatórios/metabolismo , Regulação da Expressão Gênica , Inflamação/genética , Macrófagos/patologia , Fatores de Transcrição/metabolismo , Animais , Cromatina/metabolismo , Interleucina-10/metabolismo , Ativação de Macrófagos/genética , Macrófagos/metabolismo , Camundongos , Motivos de Nucleotídeos/genética , Regiões Promotoras Genéticas , RNA Polimerase II/metabolismo , Sítio de Iniciação de Transcrição , Transcrição Gênica , Ativação Transcricional/genéticaRESUMO
The glucocorticoid receptor (GR) potently represses macrophage-elicited inflammation, however, the underlying mechanisms remain obscure. Our genome-wide analysis in mouse macrophages reveals that pro-inflammatory paused genes, activated via global negative elongation factor (NELF) dissociation and RNA Polymerase (Pol)2 release from early elongation arrest, and non-paused genes, induced by de novo Pol2 recruitment, are equally susceptible to acute glucocorticoid repression. Moreover, in both cases the dominant mechanism involves rapid GR tethering to p65 at NF-kB-binding sites. Yet, specifically at paused genes, GR activation triggers widespread promoter accumulation of NELF, with myeloid cell-specific NELF deletion conferring glucocorticoid resistance. Conversely, at non-paused genes, GR attenuates the recruitment of p300 and histone acetylation, leading to a failure to assemble BRD4 and Mediator at promoters and enhancers, ultimately blocking Pol2 initiation. Thus, GR displays no preference for a specific pro-inflammatory gene class; however, it effects repression by targeting distinct temporal events and components of transcriptional machinery.
Assuntos
Regulação da Expressão Gênica , Inflamação , Macrófagos/imunologia , Receptores de Glucocorticoides/metabolismo , Transcrição Gênica , Animais , Células Cultivadas , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos TransgênicosRESUMO
The glucocorticoid (GC) receptor (GR) suppresses inflammation by activating anti-inflammatory and repressing pro-inflammatory genes. GR-interacting protein-1 (GRIP1) is a GR corepressor in macrophages, however, whether GRIP1 mediates GR-activated transcription, and what dictates its coactivator versus corepressor properties is unknown. Here we report that GRIP1 loss in macrophages attenuates glucocorticoid induction of several anti-inflammatory targets, and that GC treatment of quiescent macrophages globally directs GRIP1 toward GR binding sites dominated by palindromic GC response elements (GRE), suggesting a non-redundant GRIP1 function as a GR coactivator. Interestingly, GRIP1 is phosphorylated at an N-terminal serine cluster by cyclin-dependent kinase-9 (CDK9), which is recruited into GC-induced GR:GRIP1:CDK9 hetero-complexes, producing distinct GRE-specific GRIP1 phospho-isoforms. Phosphorylation potentiates GRIP1 coactivator but, remarkably, not its corepressor properties. Consistently, phospho-GRIP1 and CDK9 are not detected at GR transrepression sites near pro-inflammatory genes. Thus, GR restricts actions of its own coregulator via CDK9-mediated phosphorylation to a subset of anti-inflammatory genes.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Transporte/metabolismo , Quinase 9 Dependente de Ciclina/metabolismo , Glucocorticoides/metabolismo , Macrófagos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Sítios de Ligação/genética , Proteínas de Transporte/antagonistas & inibidores , Proteínas de Transporte/genética , Linhagem Celular , Células Cultivadas , Dexametasona/farmacologia , Técnicas de Silenciamento de Genes , Glucocorticoides/farmacologia , Humanos , Inflamação/genética , Inflamação/metabolismo , Macrófagos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Fosforilação , Receptores de Glucocorticoides/metabolismo , Elementos de Resposta , Ativação TranscricionalRESUMO
Diet-induced obesity causes chronic macrophage-driven inflammation in white adipose tissue (WAT) leading to insulin resistance. WAT macrophages, however, differ in their origin, gene expression and activities: unlike infiltrating monocyte-derived inflammatory macrophages, WAT-resident macrophages counteract inflammation and insulin resistance, yet, the mechanisms underlying their transcriptional programming remain poorly understood. We recently reported that a nuclear receptor cofactor-glucocorticoid receptor (GR)-interacting protein (GRIP)1-cooperates with GR to repress inflammatory genes. Here, we show that GRIP1 facilitates macrophage programming in response to IL4 via a GR-independent pathway by serving as a coactivator for Kruppel-like factor (KLF)4-a driver of tissue-resident macrophage differentiation. Moreover, obese mice conditionally lacking GRIP1 in macrophages develop massive macrophage infiltration and inflammation in metabolic tissues, fatty livers, hyperglycaemia and insulin resistance recapitulating metabolic disease. Thus, GRIP1 is a critical regulator of immunometabolism, which engages distinct transcriptional mechanisms to coordinate the balance between macrophage populations and ultimately promote metabolic homeostasis.