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Oral administration of Ag induces regulatory T cells that express latent membrane-bound TGF-ß (latency-associated peptide [LAP]) and have been shown to play an important role in the induction of oral tolerance. We developed an in vitro model to study modulation of LAP+ on CD4+ T cells. The combination of anti-CD3 mAb, anti-CD28 mAb, and recombinant IL-2 induced expression of LAP on naive CD4+ T cells, independent of Foxp3 or exogenous TGF-ß. In vitro generated CD4+LAP+Foxp3- T cells were suppressive in vitro, inhibiting proliferation of naive CD4+ T cells and IL-17A secretion by Th17 cells. Assessing the impact of different cytokines and neutralizing Abs against cytokines, we found that LAP induction was decreased in the presence of IL-6 and IL-21, and to a lesser extent by IL-4 and TNF-α. IL-6 abrogated the in vitro induction of CD4+LAP+ T cells by STAT3-dependent inhibition of Lrrc32 (glycoprotein A repetitions predominant [GARP]), the adapter protein that tethers TGF-ß to the membrane. Oral tolerance induction was enhanced in mice lacking expression of IL-6R by CD4+ T cells and by treatment of wild-type mice with neutralizing anti-IL-6 mAb. These results suggest that proinflammatory cytokines interfere with oral tolerance induction and that blocking the IL-6 pathway is a potential strategy for enhancing oral tolerance in the setting of autoimmune and inflammatory diseases.
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Linfocitos T CD4-Positivos/inmunología , Tolerancia Inmunológica , Interleucina-6/farmacología , Factor de Crecimiento Transformador beta1/biosíntesis , Animales , Anticuerpos Monoclonales/farmacología , Complejo CD3/inmunología , Interleucina-2/farmacología , Interleucina-6/antagonistas & inhibidores , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ovalbúmina/inmunología , Factor de Transcripción STAT3/fisiología , Regulación hacia ArribaRESUMEN
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). Experimental Autoimmune Encephalomyelitis (EAE) is the most widely used animal model for the study of MS. The Suppressor of Cytokine Signaling (SOCS) 2 protein plays a critical role in regulating the immune responses. The role of SOCS2 during EAE has not been explored. EAE was induced in WT and SOCS2-/- mice using myelin oligodendrocyte glycoprotein (MOG35-55) peptide. Brain and spinal cord were examined during the peak (day 14) and recovery phase (day 28) of the disease. SOCS2 was upregulated in the brain of WT mice at the peak and recovery phase of EAE. The development of the acute phase was slower in onset in SOCS2-/- mice and was associated with reduced number of Th1 (CD3+CD4+IFN-γ +) cells in the spinal cord and brain. However, while in WT mice, maximal clinical EAE score was followed by a progressive recovery; the SOCS2-/- mice were unable to recover from locomotor impairment that occurred during the acute phase. There was a prolonged inflammatory response (increased Th1 and decreased Th2 and T regulatory cells) in the late phase of EAE in the CNS of SOCS2-/- mice. Transplantation of bone marrow cells from SOCS2-/- into irradiated WT mice resulted in higher lethality at the early phase of EAE. Altogether, these results suggest that SOCS2 plays a dual role in the immune response during EAE. It is necessary for damage during the acute phase damage but plays a beneficial role in the recovery stage of the disease.
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Encefalomielitis Autoinmune Experimental/inmunología , Encefalomielitis Autoinmune Experimental/metabolismo , Proteínas Supresoras de la Señalización de Citocinas/metabolismo , Animales , Western Blotting , Sistema Nervioso Central/inmunología , Sistema Nervioso Central/metabolismo , Encefalomielitis Autoinmune Experimental/genética , Femenino , Citometría de Flujo , Inflamación/inmunología , Inflamación/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Supresoras de la Señalización de Citocinas/genética , Células TH1/metabolismo , Células Th17/metabolismo , Células Th2/metabolismoRESUMEN
BACKGROUND & AIMS: The liver is the main hematopoietic site in embryos, becoming a crucial organ in both immunity and metabolism in adults. However, how the liver adapts both the immune system and enzymatic profile to challenges in the postnatal period remains elusive. We aimed to identify the mechanisms underlying this adaptation. METHODS: We analyzed liver samples from mice on day 0 after birth until adulthood. Human biopsies from newborns and adults were also examined. Liver immune cells were phenotyped using mass cytometry (CyTOF) and expression of several genes belonging to immune and metabolic pathways were measured. Mortality rate, bacteremia and hepatic bacterial retention after E. coli challenge were analyzed using intravital and in vitro approaches. In a set of experiments, mice were prematurely weaned and the impact on gene expression of metabolic pathways was evaluated. RESULTS: Human and mouse newborns have a sharply different hepatic cellular composition and arrangement compared to adults. We also found that myeloid cells and immature B cells primarily compose the neonatal hepatic immune system. Although neonatal mice were more susceptible to infections, a rapid evolution to an efficient immune response was observed. Concomitantly, newborns displayed a reduction of several macronutrient metabolic functions and the normal expression level of enzymes belonging to lipid and carbohydrate metabolism was reached around the weaning period. Interestingly, early weaning profoundly disturbed the expression of several hepatic metabolic pathways, providing novel insights into how dietary schemes affect the metabolic maturation of the liver. CONCLUSION: In newborns, the immune and metabolic profiles of the liver are dramatically different to those of the adult liver, which can be explained by the differences in the liver cell repertoire and phenotype. Also, dietary and antigen cues may be crucial to guide liver development during the postnatal phase. LAY SUMMARY: Newborns face major challenges in the extra-uterine life. In fact, organs need to modify their cellular composition and gene expression profile in order to adapt to changes in both microbiota and diet throughout life. The liver is interposed between the gastrointestinal system and the systemic circulation, being the destination of all macronutrients and microbial products from the gut. Therefore, it is expected that delicately balanced mechanisms govern the transformation of a neonatal liver to a key organ in adults.
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Recién Nacido , Hígado/inmunología , Hígado/metabolismo , Adulto , Animales , Animales Recién Nacidos , Biopsia , Infecciones por Escherichia coli/inmunología , Femenino , Hepatocitos , Humanos , Metabolismo de los Lípidos , Hígado/citología , Metaboloma , Ratones , Ratones Endogámicos C57BL , Células Progenitoras Mieloides/inmunología , Células Progenitoras Mieloides/fisiología , Valor Nutritivo/fisiología , Fagocitos/inmunología , Células Precursoras de Linfocitos B/inmunología , DesteteRESUMEN
Mammals and microorganisms have evolved a complex and tightly controlled mutual relationship. This interaction grants protection and energy source for the microorganisms, and on the other hand, provides several immunologic, metabolic and physiological advantages for the host. The gastrointestinal tract (GI) harbors the largest bacteria diversity within the body and complex mechanisms control microbiota community under homeostasis. However, once disrupted, microbiota imbalance can lead to overt growth of resident and invasive populations, with potential risk for lethal diseases. In these cases, bacteria might also escape from the intestines and reach different organs through the blood and lymphatic circulation. To control these unwanted conditions, all body tissues are populated with resident macrophages that have the ability to capture and eliminate pathogens, avoiding their dissemination. Here we discuss the different routes for bacterial translocation from the intestinal tract, and how macrophages act in the removal of these microorganisms to prevent systemic infections and restore the homeostasis.
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Bacterias/inmunología , Microbioma Gastrointestinal/inmunología , Homeostasis/inmunología , Macrófagos/inmunología , Animales , Bacterias/metabolismo , Humanos , Hígado/inmunología , Hígado/microbiología , Pulmón/inmunología , Pulmón/microbiología , Modelos Inmunológicos , Peritoneo/inmunología , Peritoneo/microbiologíaRESUMEN
OBJECTIVE AND DESIGN: The aim of this study was to investigate the contribution of IL-33/ST2 axis in the onset and progression of acute liver injury using a mice model of drug-induced liver injury (DILI). MATERIAL AND TREATMENTS: DILI was induced by overdose administration of acetaminophen (APAP) by oral gavage in wild-type BALB/c, ST2-deficient mice and in different bone marrow chimeras. Neutrophils were depleted by anti-Ly6G and macrophages with clodronate liposomes (CLL). METHODS: Blood and liver were collected for biochemical, immunologic and genetic analyses. Mice were imaged by confocal intravital microscopy and liver non-parenchymal cells and hepatocytes were isolated for flow cytometry, genetic and immunofluorescence studies. RESULTS: Acetaminophen overdose caused a massive necrosis and accumulation of immune cells within the liver, concomitantly with IL-33 and chemokine release. Liver non-parenchymal cells were the major sensors for IL-33, and amongst them, neutrophils were the major players in amplification of the inflammatory response triggered by IL-33/ST2 signalling pathway. CONCLUSION: Blockage of IL-33/ST2 axis reduces APAP-mediated organ injury by dampening liver chemokine release and activation of resident and infiltrating liver non-parenchymal cells.
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Enfermedad Hepática Inducida por Sustancias y Drogas/inmunología , Interleucina-33/inmunología , Hígado/inmunología , Acetaminofén/toxicidad , Analgésicos no Narcóticos/toxicidad , Animales , Trasplante de Médula Ósea , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Enfermedad Hepática Inducida por Sustancias y Drogas/terapia , ADN/metabolismo , Femenino , Hepatocitos/inmunología , Inflamación/inmunología , Proteína 1 Similar al Receptor de Interleucina-1/genética , Interleucina-33/sangre , Interleucina-33/genética , Hígado/citología , Ratones Endogámicos BALB C , Ratones Noqueados , Neutrófilos/inmunología , Transducción de SeñalRESUMEN
Despite accumulating evidence indicating that neurotransmitters released by the sympathetic nervous system can modulate the activity of innate immune cells, we still know very little about how norepinephrine impacts signaling pathways in dendritic cells (DC) and the consequence of that in DC-driven T cell differentiation. In this article, we demonstrate that ß2-adrenergic receptor (ß2AR) activation in LPS-stimulated DC does not impair their ability to promote T cell proliferation; however, it diminishes IL-12p70 secretion, leading to a shift in the IL-12p70/IL-23 ratio. Although ß2AR stimulation in DC induces protein kinase A-dependent cAMP-responsive element-binding protein phosphorylation, the effect of changing the profile of cytokines produced upon LPS challenge occurs in a protein kinase A-independent manner and, rather, is associated with inhibition of the NF-κB and AP-1 signaling pathways. Moreover, as a consequence of the inverted IL-12p70/IL-23 ratio following ß2AR stimulation, LPS-stimulated DC promoted the generation of CD4(+) T cells that, upon TCR engagement, produced lower amounts of IFN-γ and higher levels of IL-17. These findings provide new insights into molecular and cellular mechanisms by which ß2AR stimulation in murine DC can influence the generation of adaptive immune responses and may explain some aspects of how sympathetic nervous system activity can modulate immune function.
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Linfocitos T CD4-Positivos/inmunología , Células Dendríticas/inmunología , Norepinefrina/inmunología , Receptores Adrenérgicos beta 2/inmunología , Transducción de Señal/inmunología , Animales , Western Blotting , Diferenciación Celular/inmunología , Ensayo de Inmunoadsorción Enzimática , Femenino , Citometría de Flujo , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , FN-kappa B/inmunología , Reacción en Cadena en Tiempo Real de la Polimerasa , Factor de Transcripción AP-1/inmunologíaRESUMEN
BACKGROUND & AIMS: Resident macrophages are derived from yolk sac precursors and seed the liver during embryogenesis. Native cells may be replaced by bone marrow precursors during extensive injuries, irradiation, and infections. We investigated the liver populations of myeloid immune cells and their location, as well as the dynamics of phagocyte repopulation after full depletion. The effects on liver function due to the substitution of original phagocytes by bone marrow-derived surrogates were also examined. METHODS: We collected and analyzed liver tissues from C57BL/6 (control), LysM-EGFP, B6 ACTb-EGFP, CCR2-/-, CD11c-EYFP, CD11c-EYFP-DTR, germ-free mice, CX3CR1gfp/gfp, CX3CR1gpf/wt, and CX3CR1-DTR-EYFP. Liver nonparenchymal cells were immunophenotyped using mass cytometry and gene expression analyses. Kupffer and dendritic cells were depleted from mice by administration of clodronate, and their location and phenotype were examined using intravital microscopy and time-of-flight mass cytometry. Mice were given acetaminophen gavage or intravenous injections of fluorescently labeled Escherichia coli, blood samples were collected and analyzed, and liver function was evaluated. We assessed cytokine profiles of liver tissues using a multiplexed array. RESULTS: Using mass cytometry and gene expression analyses, we identified 2 populations of hepatic macrophages and 2 populations of monocytes. We also identified 4 populations of dendritic cells and 1 population of basophils. After selective depletion of liver phagocytes, intravascular myeloid precursors began to differentiate into macrophages and dendritic cells; dendritic cells migrated out of sinusoids, after a delay, via the chemokine CX3CL1. The cell distribution returned to normal in 2 weeks, but the repopulated livers were unable to fully respond to drug-induced injury or clear bacteria for at least 1 month. This defect was associated with increased levels of inflammatory cytokines, and dexamethasone accelerated the repopulation of liver phagocytes. CONCLUSIONS: In studies of hepatic phagocyte depletion in mice, we found that myeloid precursors can differentiate into liver macrophages and dendritic cells, which each localize to distinct tissue compartments. During replenishment, macrophages acquire the ability to respond appropriately to hepatic injury and to remove bacteria from the blood stream.
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Antígenos CD/análisis , Células de la Médula Ósea/fisiología , Diferenciación Celular , Hígado/citología , Hígado/fisiopatología , Células Mieloides/fisiología , Acetaminofén , Animales , Células de la Médula Ósea/citología , Enfermedad Hepática Inducida por Sustancias y Drogas/inmunología , Quimiocina CX3CL1/metabolismo , Citocinas/genética , Citocinas/metabolismo , Células Dendríticas/química , Inmunofenotipificación/métodos , Microscopía Intravital , Lectinas/genética , Hígado/inmunología , Hígado/metabolismo , Macrófagos/química , Macrófagos/inmunología , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Microvasos/metabolismo , Monocitos/química , Células Mieloides/química , Fenotipo , TranscriptomaRESUMEN
The elusive nature of the liver immune system in newborns remains an important challenge, casting a shadow over our understanding of how to effectively treat and prevent diseases in children. Therefore, deeper exploration into the intricacies of neonatal immunology might be crucial for improved pediatric healthcare. Using liver intravital microscopy, we unveiled a significant population of granulocytes in the hepatic parenchyma of fetuses and newborns. Utilizing high-dimensional immunophenotyping, we showed dynamic alterations predominantly in granulocytes during neonatal development. Liver intravital microscopy from birth through adulthood captures real-time dynamics, showing a substantial presence of Ly6G + cells that persisted significantly up to 2 weeks of age. Using CyTOF, we characterized neonatal Ly6G + cells as neutrophils, confirmed by morphology and immunohistochemistry. Surprisingly, the embryonic liver hosts a distinct population of neutrophils established as early as the second gestational week, challenging conventional notions about their origin. Additionally, we observed that embryonic neutrophils occupy preferentially the extravascular space, indicating their early establishment within the liver. Hepatic neutrophils in embryos and neonates form unique cell clusters, persisting during the initial days of life, while reduced migratory capabilities in neonates are observed, potentially compensating with increased reactive oxygen species (ROS) release in response to stimuli. Finally, in vivo imaging of acute neutrophil behavior in a newborn mouse, subjected to focal liver necrosis, unveils that neonatal neutrophils exhibit a reduced migratory response. The study provides unprecedented insights into the intricate interplay of neutrophils within the liver, shedding light on their functional and dynamic characteristics during development.
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The associations between human concussions and subsequent sequelae of chronic neuropsychiatric and cardiovascular diseases such as hypertension have been reported; however, little is known about the underlying biological processes. We hypothesized that dietary changes, including a high-salt diet, disrupt the bidirectional gut-brain axis, resulting in worsening neuroinflammation and emergence of cardiovascular and behavioural phenotypes in the chronic period after repetitive closed head injury in adolescent mice. Adolescent mice were subjected to three daily closed head injuries, recovered for 12 weeks and then maintained on a high-salt diet or a normal diet for an additional 12 weeks. Experimental endpoints were haemodynamics, behaviour, microglial gene expression (bulk RNA sequencing), brain inflammation (brain tissue quantitative PCR) and microbiome diversity (16S RNA sequencing). High-salt diet did not affect systemic blood pressure or heart rate in sham or injured mice. High-salt diet increased anxiety-like behaviour in injured mice compared to sham mice fed with high-salt diet and injured mice fed with normal diet. Increased anxiety in injured mice that received a high-salt diet was associated with microgliosis and a proinflammatory microglial transcriptomic signature, including upregulation in interferon-gamma, interferon-beta and oxidative stress-related pathways. Accordingly, we found upregulation of tumour necrosis factor-alpha and interferon-gamma mRNA in the brain tissue of high salt diet-fed injured mice. High-salt diet had a larger effect on the gut microbiome composition than repetitive closed head injury. Increases in gut microbes in the families Lachnospiraceae, Erysipelotrichaceae and Clostridiaceae were positively correlated with anxiety-like behaviours. In contrast, Muribaculaceae, Acholeplasmataceae and Lactobacillaceae were negatively correlated with anxiety in injured mice that received a high-salt diet, a time-dependent effect. The findings suggest that high-salt diet, administered after a recovery period, may affect neurologic outcomes following mild repetitive head injury, including the development of anxiety. This effect was linked to microbiome dysregulation and an exacerbation of microglial inflammation, which may be physiological targets to prevent behavioural sequelae in the chronic period after mild repetitive head injury. The data suggest an important contribution of diet in determining long-term outcomes after mild repetitive head injury.
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Kupffer cells (KCs) are self-maintained tissue-resident macrophages that line liver sinusoids and play an important role on host defense. It has been demonstrated that upon infection or intense liver inflammation, KCs might be severely depleted and replaced by immature monocytic cells; however, the mechanisms of cell death and the alterations on liver immunity against infections deserves further investigation. We explored the impact of acute Plasmodium infection on KC biology and on the hepatic immune response against secondary infections. Similar to patients, infection with Plasmodium chabaudi induced acute liver damage as determined by serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation. This was associated with accumulation of hemozoin, increased of proinflammatory response and impaired bacterial and viral clearance, which led to pathogen spread to other organs. In line with this, mice infected with Plasmodium had enhanced mortality during secondary infections, which was associated with increased production of mitochondrial superoxide, lipid peroxidation and increased free iron within KCs-hallmarks of cell death by ferroptosis. Therefore, we revealed that accumulation of iron with KCs, triggered by uptake of circulating hemozoin, is a novel mechanism of macrophage depletion and liver inflammation during malaria, providing novel insights on host susceptibility to secondary infections. Malaria can cause severe liver damage, along with depletion of liver macrophages, which can predispose individuals to secondary infections and enhance the chances of death.
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Coinfección , Malaria , Plasmodium chabaudi , Sobreinfección , Ratones , Animales , Plasmodium chabaudi/fisiología , Macrófagos del Hígado/metabolismo , Coinfección/complicaciones , Malaria/metabolismo , Muerte Celular , Inflamación/metabolismo , Hierro/metabolismoRESUMEN
OBJECTIVES: The aim of this study was to investigate putative different outcomes on the development of non-alcoholic fatty liver disease in mice using fat options regularly used in human nutrition. METHODS: Male C57BL/6 mice were fed a control diet, and four different high-fat diets (HFD: 40% calories from fat; Research Diet, Inc., New Brunswick, New Jersey, USA) for 16 and 30 wk. HFDs had different common fat sources, including trans-fat, non-trans-fat palm oil (Primex-Z), palm oil alone, and corn oil alone. Mice were sacrificed and samples were collected for analysis. RESULTS: Using an unprecedented combination of in vivo imaging with immunometabolic phenotyping, we revealed that a HFD induced a major increase in hepatic lipid droplet deposition compared with control mice, being significantly higher in Primex-Z-fed mice. All HFD mice had similar or less weight gain as control mice; however, Primex-Z ingestion led to a higher increase in adiposity index (~90% increase) compared with other fat sources. Gene expression of isolated liver immune cells revealed large changes in expression of several inflammatory pathways, which were also more elevated in Primex-Z-fed mice, including Tnf (~20-fold), Il1b (~60-fold), and Tgfb (2.5-fold). Immunophenotyping and in vivo analysis showed that the frequency of hepatic immune cells was also disturbed during different HFD contents, rendering not only Kupffer cell depletion, but also reduced bacterial arresting ability. CONCLUSION: Different fat dietary sources imprint different immune and metabolic effects in the liver during consumption of an HFD. The present data highlighted that Primex-Z-a novel non-trans-fat-is not only able to damage hepatocytes, but also to impair liver ability to clear blood-borne infections.
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Infecciones Bacterianas , Enfermedad del Hígado Graso no Alcohólico , Animales , Dieta Alta en Grasa/efectos adversos , Ingestión de Alimentos , Hígado , Masculino , Ratones , Ratones Endogámicos C57BL , Enfermedad del Hígado Graso no Alcohólico/etiologíaRESUMEN
In a model of peripherally induced inflammatory pain in rats, selective inhibitors of cyclooxygenase (COX)-2 raised nociceptive thresholds above basal values, an effect referred to as "hypoalgesia". However other, non-selective, inhibitors of COX (indomethacin, piroxicam) or a selective inhibitor of COX-1 did not induce hypoalgesia in this model, implying that COX inhibition was not causally related to the hypoalgesic effect. Here, we have assessed whether other COX-2 inhibitors or other sulphonamides, apart from celecoxib could exhibit hypoalgesia in our model of inflammatory pain. Inflammation was induced in one hind paw of rats by intraplantar injection of carrageenan (250 µg). Nociceptive thresholds to mechanical stimulation were measured in the inflamed and contralateral paws for 6 h after carrageenan. Three sulphonamides, celecoxib itself, furosemide (a loop diuretic), acetazolamide (a carbonic anhydrase inhibitor), or a selective COX-2 inhibitor lacking the sulphonamide group, lumiracoxib, were injected s.c., 30 min before the pro-inflammatory stimulus. Naltrexone, a non-selective opioid antagonist was also administered s.c., 30 min before test drugs. Furosemide and acetazolamide dose-dependently induced hypoalgesia in the inflamed paw, as did celecoxib. However, lumiracoxib only produced anti-hyperalgesia. Pre-treatment with naltrexone completely prevented the hypoalgesia induced by the sulphonamides, but only partially prevented the anti-hyperalgesic effect of lumiracoxib. Taken together, our results suggest that the sulphonamide group in the structure of celecoxib is more critical for the development of hypoalgesia in our model than its ability to inhibit COX-2. Further, other sulphonamides lacking significant COX inhibition were also able to exhibit hypoalgesic effects, mediated by the endogenous opioid system.
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Inhibidores de la Ciclooxigenasa 2/química , Inhibidores de la Ciclooxigenasa 2/farmacología , Dolor/tratamiento farmacológico , Pirazoles/química , Pirazoles/farmacología , Sulfonamidas/química , Sulfonamidas/farmacología , Acetazolamida/administración & dosificación , Acetazolamida/química , Acetazolamida/farmacología , Animales , Celecoxib , Inhibidores de la Ciclooxigenasa 2/administración & dosificación , Diclofenaco/administración & dosificación , Diclofenaco/análogos & derivados , Diclofenaco/química , Diclofenaco/farmacología , Relación Dosis-Respuesta a Droga , Hiperalgesia/inducido químicamente , Hiperalgesia/tratamiento farmacológico , Hiperalgesia/prevención & control , Inflamación/inducido químicamente , Inflamación/tratamiento farmacológico , Masculino , Naltrexona/administración & dosificación , Naltrexona/farmacología , Antagonistas de Narcóticos/administración & dosificación , Antagonistas de Narcóticos/farmacología , Dimensión del Dolor/efectos de los fármacos , Umbral del Dolor/efectos de los fármacos , Pirazoles/administración & dosificación , Ratas , Ratas Sprague-Dawley , Sulfonamidas/administración & dosificaciónRESUMEN
Neutrophils were classically described as powerful effectors of acute inflammation, and their main purpose was assumed to be restricted to pathogen killing through production of oxidants. As consequence, neutrophils also may lead to significant collateral damage to the healthy tissues, and after performing these tasks, these leukocytes are supposed to die within tissues. However, there is a growing body of evidence showing that neutrophils also play a pivotal role in the resolution phases of inflammation, because they can modulate tissue environment due to secretion of different kind of cytokines. Drug-induced liver injury (DILI) is a worldwide concern being one of the most prevalent causes of liver transplantation, and is well established that there is an intense neutrophil recruitment into necrotic liver during DILI. However, information if such abundant granulocyte infiltration is also linked to the tissue repairing phase of hepatic injury is still largely elusive. Here, we investigated the dynamics of neutrophil trafficking within blood, bone marrow, and liver during hepatic inflammation, and how changes in their gene expression profile could drive the resolution events during acetaminophen (APAP)-induced liver injury. We found that neutrophils remained viable during longer periods following liver damage, because they avidly patrolled necrotic areas and up-regulated pro-resolutive genes, including Tgfb, Il1r2, and Fpr2. Adoptive transference of "resolutive neutrophils" harvested from livers at 72 h after injury to mice at the initial phases of injury (6 h after APAP) significantly rescued organ injury. Thus, we provide novel insights on the role of neutrophils not only in the injury amplification, but also in the resolution phases of inflammation.
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Enfermedad Hepática Inducida por Sustancias y Drogas/inmunología , Hígado/inmunología , Infiltración Neutrófila , Neutrófilos/inmunología , Acetaminofén/efectos adversos , Acetaminofén/farmacología , Animales , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/inmunología , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Femenino , Hígado/patología , Ratones , Neutrófilos/patología , Receptores de Formil Péptido/inmunología , Receptores Tipo II de Interleucina-1/inmunología , Factor de Crecimiento Transformador beta/inmunología , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/inmunologíaRESUMEN
BACKGROUND & AIMS: The precise determination of non-alcoholic fatty liver disease (NAFLD) onset is challenging. Thus, the initial hepatic responses to fat accumulation, which may be fundamental to our understanding of NAFLD evolution and clinical outcomes, are largely unknown. Herein, we chronologically mapped the immunologic and metabolic changes in the liver during the early stages of fatty liver disease in mice and compared this with human NAFLD samples. METHODS: Liver biopsies from patients with NAFLD (NAFLD activity score [NAS] 2-3) were collected for gene expression profiling. Mice received a high-fat diet for short periods to mimic initial steatosis and the hepatic immune response was investigated using a combination of confocal intravital imaging, gene expression, cell isolation, flow cytometry and bone marrow transplantation assays. RESULTS: We observed major immunologic changes in patients with NAS 2-3 and in mice in the initial stages of NAFLD. In mice, these changes significantly increased mortality rates upon drug-induced liver injury, as well as predisposing mice to bacterial infections. Moreover, deletion of Toll-like receptor 4 in liver cells dampened tolerogenesis, particularly in Kupffer cells, in the initial stages of dietary insult. CONCLUSION: The hepatic immune system acts as a sentinel for early and minor changes in hepatic lipid content, mounting a biphasic response upon dietary insult. Priming of liver immune cells by gut-derived Toll-like receptor 4 ligands plays an important role in liver tolerance in initial phases, but continuous exposure to insults may lead to damage and reduced ability to control infections. LAY SUMMARY: Fatty liver is a very common form of hepatic disease, leading to millions of cases of cirrhosis every year. Patients are often asymptomatic until becoming very sick. Therefore, it is important that we expand our knowledge of the early stages of disease pathogenesis, to enable early diagnosis. Herein, we show that even in the early stages of fatty liver disease, there are significant alterations in genes involved in the inflammatory response, suggesting that the hepatic immune system is disturbed even following minor and undetectable changes in liver fat content. This could have implications for the diagnosis and clinical management of fatty liver disease.
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Leukocytes are a large population of cells spread within most tissues in the body. These cells may be either sessile (called as resident cells) or circulating leukocytes, which travel long journeys inside the vessels during their lifespan. Although production and maturation of these leukocytes in adults primarily occur in the bone marrow, it is well known that this process-called hematopoiesis-started in the embryonic life in different sites, including the yolk sac, placenta, and the liver. In this review, we will discuss how the liver acts as a pivotal site for leukocyte maturation during the embryo phase, and also how the most frequent liver-resident immune cell populations-namely Kupffer cells, dendritic cells, and lymphocytes-play a vital role in both tolerance and inflammatory responses to antigens from food, microbiota, and pathogens.
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Leucocitos/citología , Hígado/citología , Animales , Linaje de la Célula , Hematopoyesis , Humanos , Fagocitos/citologíaRESUMEN
Pretreatment using celecoxib, a cyclooxygenase (COX) 2 inhibitor, or indomethacin, a nonselective COX inhibitor, reduced lypopolyssaccharide (LPS)-induced leukocyte migration to the rat peritoneal cavity. The effect of celecoxib (12 mg/kg) or indomethacin (2 mg/kg) on neutrophil chemotaxis induced by formyl-methionyl-leucyl-phenylalanine (FMLP) in an in vitro chemotactic assay (Boyden chamber) was investigated. Celecoxib and indomethacin inhibited chemotaxis induced by FMLP (Control=26.6+/-1.45, Celecoxib=12.8+/-3.04, Indomethacin=6.26+/-2.19 cells/field). When observed under intravital microscopy, a mouse cremaster preparation was used to assess the microvasculature to further investigate which step of cell recruitment was affected by these drugs. Celecoxib and indomethacin inhibited leukocyte migration induced by 0.05 microg/kg LPS injected into the cremaster muscle. However, the effect of celecoxib was associated with reduced cell rolling and adhesion, whereas indomethacin was only effective at inhibiting cell adhesion. Furthermore, SC560 pretreatment (a COX-1 selective inhibitor) of normal or LPS-challenged tissues did not alter leukocyte migration or cell adhesion, but it did enhance leukocyte rolling activity in both cases. Taken together, these results indicate that: 1) COX-1 activity is mainly related to leukocyte traffic under physiological conditions, and 2) COX-2 activity is mainly related to cell traffic under inflammatory conditions in vascular beds, suggesting a possible effect of selective COX-2 inhibitors on the expression of adhesion molecules.
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Neutrófilos/fisiología , Prostaglandina-Endoperóxido Sintasas/fisiología , Animales , Celecoxib , Adhesión Celular/efectos de los fármacos , Movimiento Celular , Separación Celular , Quimiotaxis de Leucocito/efectos de los fármacos , Ciclooxigenasa 1/efectos de los fármacos , Inhibidores de la Ciclooxigenasa 2/farmacología , Inhibidores de la Ciclooxigenasa/farmacología , Interpretación Estadística de Datos , Endotelio Vascular/efectos de los fármacos , Femenino , Indometacina/farmacología , Isoenzimas/fisiología , Masculino , Ratones , Infiltración Neutrófila/efectos de los fármacos , Pirazoles/farmacología , Ratas , Ratas Sprague-Dawley , Sulfonamidas/farmacologíaRESUMEN
Previous studies have reported that microglia depletion leads to impairment of synapse formation and these cells rapidly repopulate from CNS progenitors. However, the impact of microglia depletion and repopulation in the long-term state of the CNS environment has not been characterized. Here, we report that acute and synchronous microglia depletion and subsequent repopulation induces gray matter microgliosis, neuronal death in the somatosensory cortex and ataxia-like behavior. We find a type 1 interferon inflammatory signature in degenerating somatosensory cortex from microglia-depleted mice. Transcriptomic and mass cytometry analysis of repopulated microglia demonstrates an interferon regulatory factor 7-driven activation state. Minocycline and anti-IFNAR1 antibody treatment attenuate the CNS type 1 interferon-driven inflammation, restore microglia homeostasis and reduce ataxic behavior. Neither microglia depletion nor repopulation impact neuropathology or T-cell responses during experimental autoimmune encephalomyelitis. Together, we found that acute microglia ablation induces a type 1 interferon activation state of gray matter microglia associated with acute neurodegeneration.
Asunto(s)
Muerte Celular/inmunología , Encefalomielitis Autoinmune Experimental/inmunología , Sustancia Gris/inmunología , Interferón Tipo I/inmunología , Microglía/inmunología , Neuronas/inmunología , Corteza Somatosensorial/inmunología , Animales , Antibacterianos/farmacología , Ataxia/inmunología , Ataxia/patología , Encefalomielitis Autoinmune Experimental/patología , Citometría de Flujo , Perfilación de la Expresión Génica , Sustancia Gris/patología , Homeostasis , Inmunohistoquímica , Factor 7 Regulador del Interferón/genética , Factor 7 Regulador del Interferón/inmunología , Ratones , Microscopía Confocal , Minociclina/farmacología , Neuronas/patología , Receptor de Interferón alfa y beta/antagonistas & inhibidores , Prueba de Desempeño de Rotación con Aceleración Constante , Corteza Somatosensorial/patologíaRESUMEN
Hepatocytes may rupture after a drug overdose, and their intracellular contents act as damage-associated molecular patterns (DAMPs) that lead to additional leukocyte infiltration, amplifying the original injury. Necrosis-derived DNA can be recognized as a DAMP, activating liver non-parenchymal cells (NPCs). We hypothesized that NPCs react to DNA by releasing interferon (IFN)-1, which amplifies acetaminophen (APAP)-triggered liver necrosis. We orally overdosed different knockout mouse strains to investigate the pathways involved in DNA-mediated amplification of APAP-induced necrosis. Mice were imaged under intravital confocal microscopy to estimate injury progression, and hepatocytes and liver NPCs were differentially isolated for gene expression assays. Flow cytometry (FACS) using a fluorescent reporter mouse estimated the interferon-beta production by liver leukocytes under different injury conditions. We also treated mice with DNase to investigate the role of necrosis DNA signaling in IFN-1 production. Hepatocytes released a large amount of DNA after APAP overdose, which was not primarily sensed by these cells. However, liver NPCs promptly sensed such environmental disturbances and activated several DNA sensing pathways. Liver NPCs synthesized and released IFN-1, which was associated with concomitant hepatocyte necrosis. Ablation of IFN-1 recognition in interferon α/ß receptor (IFNAR-/-) mice delayed APAP-mediated liver necrosis and dampened IFN-1 sensing pathways. We demonstrated a novel loop involving DNA recognition by hepatic NPCs and additional IFN-1 mediated hepatocyte death.
RESUMEN
Dietary supplementation with conjugated linoleic acid (CLA) has been proposed for weight management and to prevent gut inflammation. However, some animal studies suggest that supplementation with CLA leads to the development of nonalcoholic fatty liver disease. The aims of this study were to test the efficiency of CLA in preventing dextran sulfate sodium (DSS)-induced colitis, to analyze the effects of CLA in the liver function, and to access putative liver alterations upon CLA supplementation during colitis. So, C57BL/6 mice were supplemented for 3 weeks with either control diet (AIN-G) or 1% CLA-supplemented diet. CLA content in the diet and in the liver of mice fed CLA containing diet were accessed by gas chromatography. On the first day of the third week of dietary treatment, mice received ad libitum a 1.5%-2.5% DSS solution for 7 days. Disease activity index score was evaluated; colon and liver samples were stained by hematoxylin and eosin for histopathology analysis and lamina propria cells were extracted to access the profile of innate cell infiltrate. Metabolic alterations before and after colitis induction were accessed by an open calorimetric circuit. Serum glucose, cholesterol, triglycerides and alanine aminotransaminase were measured; the content of fat in liver and feces was also accessed. CLA prevented weight loss, histopathologic and macroscopic signs of colitis, and inflammatory infiltration. Mice fed CLA-supplemented without colitis induction diet developed steatosis, which was prevented in mice with colitis probably due to the higher lipid consumption as energy during gut inflammation. This result suggests that CLA is safe for use during gut inflammation but not at steady-state conditions.
Asunto(s)
Colitis/dietoterapia , Ácidos Linoleicos Conjugados/farmacología , Enfermedad del Hígado Graso no Alcohólico/inducido químicamente , Alanina Transaminasa/sangre , Animales , Antiinflamatorios no Esteroideos/efectos adversos , Antiinflamatorios no Esteroideos/farmacología , Colitis/inducido químicamente , Colitis/prevención & control , Colon/efectos de los fármacos , Colon/inmunología , Colon/patología , Sulfato de Dextran/toxicidad , Suplementos Dietéticos , Femenino , Inmunidad Innata/efectos de los fármacos , Inmunidad Innata/fisiología , Ácido Linoleico/metabolismo , Ácidos Linoleicos Conjugados/efectos adversos , Hígado/citología , Hígado/efectos de los fármacos , Hígado/metabolismo , Ratones Endogámicos C57BLRESUMEN
Acetaminophen (APAP) poisoning is one of the leading causes of acute hepatic failure and liver transplantation is often the only lifesaving alternative. During the course of hepatocyte necrosis, an intense accumulation of neutrophils is often observed within the liver microenvironment. Despite the classic idea that neutrophil accumulation in tissues causes collateral tissue damage, there is a growing body of evidence showing that neutrophils can also orchestrate the resolution of inflammation. In this work, drug-induced liver injury was induced by oral administration of APAP and pharmacological intervention was made 12 h after this challenge. Liver injury and repair kinetics were evaluated by a novel combination of enzyme quantifications, ELISA, specific antagonists of neutrophil enzymes and confocal intravital microscopy. We have demonstrated that neutrophil infiltration is not only involved in injury amplification, but also in liver tissue repair after APAP-induced liver injury. In fact, while neutrophil depletion led to reduced hepatic necrosis during APAP poisoning, injury recovery was also delayed in neutropenic mice. The mechanisms underlying the neutrophil reparative role involved rapid degranulation and matrix metalloproteinases (MMPs) activity. Our data highlights the crucial role of neutrophils, in particular for MMPs, in the resolution phase of APAP-induced inflammatory response.