RESUMO
Glucocorticoid synthesis by adrenal glands (AGs) is regulated by the hypothalamic-pituitary-adrenal axis to facilitate stress responses when the host is exposed to stimuli. Recent studies implicate macrophages as potential steroidogenic regulators, but the molecular mechanisms by which AG macrophages exert such influence remain unclear. In this study, we investigated the role of AG macrophages in response to cold challenge or atherosclerotic inflammation as physiologic models of acute or chronic stress. Using single-cell RNA sequencing, we observed dynamic AG macrophage polarization toward classical activation and lipid-associated phenotypes following acute or chronic stimulation. Among transcriptional alterations induced in macrophages, triggering receptor expressed on myeloid cells 2 (Trem2) was highlighted because of its upregulation following stress. Conditional deletion of macrophage Trem2 revealed a protective role in stress responses. Mechanistically, Trem2 deletion led to increased AG macrophage death, abolished the TGF-ß-producing capacity of AG macrophages, and resulted in enhanced glucocorticoid production. In addition, enhanced glucocorticoid production was replicated by blockade of TGF-ß signaling. Together, these observations suggest that AG macrophages restrict steroidogenesis through Trem2 and TGF-ß, which opens potential avenues for immunotherapeutic interventions to resolve stress-related disorders.
Assuntos
Glândulas Suprarrenais , Glucocorticoides , Macrófagos , Glicoproteínas de Membrana , Receptores Imunológicos , Fator de Crescimento Transformador beta , Animais , Macrófagos/metabolismo , Macrófagos/imunologia , Camundongos , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/genética , Glucocorticoides/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Receptores Imunológicos/metabolismo , Receptores Imunológicos/genética , Glândulas Suprarrenais/metabolismo , Masculino , Camundongos Knockout , Camundongos Endogâmicos C57BL , Transdução de SinaisRESUMO
Stress exposure has been shown to modulate innate and adaptive immune responses. Indeed, stress favors myelopoiesis and monocyte generation and contributes to cardiovascular disease development. As sex hormones regulate innate and adaptive immune responses, we decided to investigate whether stress exposure leads to a different immune response in female and male mice. Our data demonstrated that psychosocial stressinduced neutrophilia in male, but not female mice. Importantly, we identified that B-cell numbers were reduced in female, but not male mice upon exposure to stress. Thus, our study revealed that the stress-induced immune alterations are sex-dependent, and this is an important feature to consider for future investigations.
Assuntos
Hematopoese , Estresse Psicológico , Animais , Feminino , Estresse Psicológico/imunologia , Masculino , Camundongos , Hematopoese/imunologia , Linfócitos B/imunologia , Neutrófilos/imunologia , Leucócitos/imunologia , Camundongos Endogâmicos C57BL , Fatores Sexuais , Caracteres SexuaisRESUMO
In mouse peritoneal and other serous cavities, the transcription factor GATA6 drives the identity of the major cavity resident population of macrophages, with a smaller subset of cavity-resident macrophages dependent on the transcription factor IRF4. Here we showed that GATA6+ macrophages in the human peritoneum were rare, regardless of age. Instead, more human peritoneal macrophages aligned with mouse CD206+ LYVE1+ cavity macrophages that represent a differentiation stage just preceding expression of GATA6. A low abundance of CD206+ macrophages was retained in C57BL/6J mice fed a high-fat diet and in wild-captured mice, suggesting that differences between serous cavity-resident macrophages in humans and mice were not environmental. IRF4-dependent mouse serous cavity macrophages aligned closely with human CD1c+CD14+CD64+ peritoneal cells, which, in turn, resembled human peritoneal CD1c+CD14-CD64- cDC2. Thus, major populations of serous cavity-resident mononuclear phagocytes in humans and mice shared common features, but the proportions of different macrophage differentiation stages greatly differ between the two species, and dendritic cell (DC2)-like cells were especially prominent in humans.
Assuntos
Macrófagos Peritoneais , Macrófagos , Humanos , Camundongos , Animais , Camundongos Endogâmicos C57BL , Macrófagos/metabolismo , Macrófagos Peritoneais/metabolismo , Diferenciação Celular , Células DendríticasRESUMO
Despite the ubiquitous function of macrophages across the body, the diversity, origin, and function of adrenal gland macrophages remain largely unknown. We define the heterogeneity of adrenal gland immune cells using single-cell RNA sequencing and use genetic models to explore the developmental mechanisms yielding macrophage diversity. We define populations of monocyte-derived and embryonically seeded adrenal gland macrophages and identify a female-specific subset with low major histocompatibility complex (MHC) class II expression. In adulthood, monocyte recruitment dominates adrenal gland macrophage maintenance in female mice. Adrenal gland macrophage sub-tissular distribution follows a sex-dimorphic pattern, with MHC class IIlow macrophages located at the cortico-medullary junction. Macrophage sex dimorphism depends on the presence of the cortical X-zone. Adrenal gland macrophage depletion results in altered tissue homeostasis, modulated lipid metabolism, and decreased local aldosterone production during stress exposure. Overall, these data reveal the heterogeneity of adrenal gland macrophages and point toward sex-restricted distribution and functions of these cells.
Assuntos
Glândulas Suprarrenais , Macrófagos , Monócitos , Caracteres Sexuais , Glândulas Suprarrenais/metabolismo , Animais , Feminino , Antígenos de Histocompatibilidade Classe II/genética , Contagem de Leucócitos , Macrófagos/metabolismo , Masculino , CamundongosRESUMO
Brown adipose tissue (BAT) contains many immune cells. The presence of macrophages, monocytes, dendritic cells, T cells, B cells, and mast cells was documented in BAT. However, in comparison to white adipose tissue, relatively little is known on the impact of immune cells on BAT function. By directly interacting with BAT stromal cells, or by secreting pro- and anti-inflammatory mediators, immune cells modulate BAT activation and subsequently influence on adaptative thermogenesis and heat generation. In the current manuscript, we will focus on the diversity and functions of BAT immune cells.
RESUMO
Macrophages rely on tightly integrated metabolic rewiring to clear dying neighboring cells by efferocytosis during homeostasis and disease. Here we reveal that glutaminase-1-mediated glutaminolysis is critical to promote apoptotic cell clearance by macrophages during homeostasis in mice. In addition, impaired macrophage glutaminolysis exacerbates atherosclerosis, a condition during which, efficient apoptotic cell debris clearance is critical to limit disease progression. Glutaminase-1 expression strongly correlates with atherosclerotic plaque necrosis in patients with cardiovascular diseases. High-throughput transcriptional and metabolic profiling reveals that macrophage efferocytic capacity relies on a non-canonical transaminase pathway, independent from the traditional requirement of glutamate dehydrogenase to fuel É-ketoglutarate-dependent immunometabolism. This pathway is necessary to meet the unique requirements of efferocytosis for cellular detoxification and high-energy cytoskeletal rearrangements. Thus, we uncover a role for non-canonical glutamine metabolism for efficient clearance of dying cells and maintenance of tissue homeostasis during health and disease in mouse and humans.
Assuntos
Aminação , Glutamina/metabolismo , Fosforilação Oxidativa , Animais , Camundongos , FagocitoseRESUMO
Monocytes are part of the mononuclear phagocytic system. Monocytes play a central role during inflammatory conditions and a better understanding of their dynamics might open therapeutic opportunities. In the present study, we focused on the characterization and impact of monocytes on brown adipose tissue (BAT) functions during tissue remodeling. Single-cell RNA sequencing analysis of BAT immune cells uncovered a large diversity in monocyte and macrophage populations. Fate-mapping experiments demonstrated that the BAT macrophage pool requires constant replenishment from monocytes. Using a genetic model of BAT expansion, we found that brown fat monocyte numbers were selectively increased in this scenario. This observation was confirmed using a CCR2-binding radiotracer and positron emission tomography. Importantly, in line with their tissue recruitment, blood monocyte counts were decreased while bone marrow hematopoiesis was not affected. Monocyte depletion prevented brown adipose tissue expansion and altered its architecture. Podoplanin engagement is strictly required for BAT expansion. Together, these data redefine the diversity of immune cells in the BAT and emphasize the role of monocyte recruitment for tissue remodeling.
Assuntos
Tecido Adiposo Marrom/citologia , Monócitos/fisiologia , Adiponectina/genética , Tecido Adiposo Marrom/fisiologia , Animais , Diferenciação Celular/genética , Contagem de Leucócitos , Macrófagos/citologia , Macrófagos/fisiologia , Glicoproteínas de Membrana/metabolismo , Camundongos Transgênicos , Monócitos/citologia , Tomografia por Emissão de Pósitrons , Receptores CCR2/genética , Receptores CCR2/metabolismoRESUMO
Metabolism plays a key role in controlling immune cell functions. In this review, we will discuss the diversity of plaque resident myeloid cells and will focus on their metabolic demands that could reflect on their particular intraplaque localization. Defining the metabolic configuration of plaque resident myeloid cells according to their topologic distribution could provide answers to key questions regarding their functions and contribution to disease development.
Assuntos
Aterosclerose , Placa Aterosclerótica , Humanos , MacrófagosRESUMO
Along with respiratory tract disease per se, viral respiratory infections can also cause extrapulmonary complications with a potentially critical impact on health. In the present study, we used an experimental model of influenza A virus (IAV) infection to investigate the nature and outcome of the associated gut disorders. In IAV-infected mice, the signs of intestinal injury and inflammation, altered gene expression, and compromised intestinal barrier functions peaked on day 7 postinfection. As a likely result of bacterial component translocation, gene expression of inflammatory markers was upregulated in the liver. These changes occurred concomitantly with an alteration of the composition of the gut microbiota and with a decreased production of the fermentative, gut microbiota-derived products short-chain fatty acids (SCFAs). Gut inflammation and barrier dysfunction during influenza were not attributed to reduced food consumption, which caused in part gut dysbiosis. Treatment of IAV-infected mice with SCFAs was associated with an enhancement of intestinal barrier properties, as assessed by a reduction in the translocation of dextran and a decrease in inflammatory gene expression in the liver. Lastly, SCFA supplementation during influenza tended to reduce the translocation of the enteric pathogen Salmonella enterica serovar Typhimurium and to enhance the survival of doubly infected animals. Collectively, influenza virus infection can remotely impair the gut's barrier properties and trigger secondary enteric infections. The latter phenomenon can be partially countered by SCFA supplementation.
Assuntos
Infecções por Enterobacteriaceae/etiologia , Ácidos Graxos Voláteis/biossíntese , Interações Hospedeiro-Patógeno , Vírus da Influenza A/fisiologia , Influenza Humana/complicações , Influenza Humana/virologia , Mucosa Intestinal/metabolismo , Interações Microbianas , Suscetibilidade a Doenças , Disbiose , Infecções por Enterobacteriaceae/metabolismo , Interações Hospedeiro-Patógeno/imunologia , Humanos , Influenza Humana/metabolismo , Mucosa Intestinal/imunologiaRESUMO
Inflammasomes are signalling platforms that are assembled in response to infection or sterile inflammation by cytosolic pattern recognition receptors. The consequent inflammasome-triggered caspase-1 activation is critical for the host defence against pathogens. During infection, NLRP3, which is a pattern recognition receptor that is also known as cryopyrin, triggers the assembly of the inflammasome-activating caspase-1 through the recruitment of ASC and Nek7. The activation of the NLRP3 inflammasome is tightly controlled both transcriptionally and post-translationally. Despite the importance of the NLRP3 inflammasome regulation in autoinflammatory and infectious diseases, little is known about the mechanism controlling the activation of NLRP3 and the upstream signalling that regulates the NLRP3 inflammasome assembly. We have previously shown that the Rho-GTPase-activating toxin from Escherichia coli cytotoxic necrotizing factor-1 (CNF1) activates caspase-1, but the upstream mechanism is unclear. Here, we provide evidence of the role of the NLRP3 inflammasome in sensing the activity of bacterial toxins and virulence factors that activate host Rho GTPases. We demonstrate that this activation relies on the monitoring of the toxin's activity on the Rho GTPase Rac2. We also show that the NLRP3 inflammasome is activated by a signalling cascade that involves the p21-activated kinases 1 and 2 (Pak1/2) and the Pak1-mediated phosphorylation of Thr 659 of NLRP3, which is necessary for the NLRP3-Nek7 interaction, inflammasome activation and IL-1ß cytokine maturation. Furthermore, inhibition of the Pak-NLRP3 axis decreases the bacterial clearance of CNF1-expressing UTI89 E. coli during bacteraemia in mice. Taken together, our results establish that Pak1 and Pak2 are critical regulators of the NLRP3 inflammasome and reveal the role of the Pak-NLRP3 signalling axis in vivo during bacteraemia in mice.
Assuntos
Bacteriemia/metabolismo , Toxinas Bacterianas/metabolismo , Infecções por Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Animais , Bacteriemia/imunologia , Bacteriemia/microbiologia , Carga Bacteriana , Toxinas Bacterianas/genética , Escherichia coli/genética , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Imunidade Inata , Camundongos , Fosforilação , Transdução de Sinais , Quinases Ativadas por p21/metabolismo , Proteínas rac de Ligação ao GTP/genética , Proteína RAC2 de Ligação ao GTPRESUMO
Lymphatic collecting vessels and lymph nodes are inevitably embedded in adipose tissue. The physiological significance of this observation remains still not elucidated. However, obesity is characterized by impaired lymphatic function and increased vessel permeability. Inversely, lymphatic dysfunction induces obesity in mice, suggesting a significant interplay between lymphatic vessels and the adipose tissue. Therefore, understanding factors leading to lymphatic dysfunction might open new therapeutic windows to prevent obesity and associated comorbidities. The first step in this process requires a precise and detailed visualization of the lymphatic network in healthy and inflamed adipose tissue. Here, we describe a rapid, inexpensive, and efficient method that allows to label and analyze lymphatic and blood vessels. This approach takes advantage of the skin-draining brachial lymph node localization within the subcutaneous adipose tissue. The lymphatic arborization of this tissue can be revealed by injecting fluorochrome-conjugated lectins subcutaneously. Moreover, the in vivo labeling approach provides a way to evaluate lymphatic vessel density and functions. Coupled to blood vessel, adipocyte and immune cell staining, the protocol allows for high-resolution mapping of the subcutaneous adipose tissue by 3D imaging.
Assuntos
Vasos Sanguíneos/patologia , Vasos Linfáticos/patologia , Obesidade/sangue , Obesidade/patologia , Animais , Linfonodos/patologia , Camundongos Endogâmicos C57BL , Coloração e Rotulagem , Gordura Subcutânea/irrigação sanguíneaRESUMO
Macrophages play a central role during infection, inflammation and tissue homeostasis maintenance. Macrophages have been identified in all organs and their core transcriptomic signature and functions differ from one tissue to another. Interestingly, macrophages have also been identified in the peritoneal cavity and these cells have been extensively used as a model for phagocytosis, efferocytosis and polarization. Peritoneal macrophages are involved in B-cell IgA production, control of inflammation and wound healing following thermal-induced liver surface injury. These cells presumably require and interact with the omentum, where milky spot stromal cells have been proposed to secrete CSF1 (colony stimulating factor 1). Peritoneal macrophages depend on CSF1 for their generation and survival, but the identity of CSF1 producing cells inside the large peritoneal cavity remains unknown. Here we investigated peritoneal macrophage localization and their interaction with mesothelial cells, the major cell type predicted to secrete CSF1. Our data revealed that mesothelial cells produce membrane bound and secreted CSF1 that both sustain peritoneal macrophage growth.