RESUMO
In the respiratory tract, intracellular 3',5'-cAMP mediates smooth muscle relaxation triggered by the ß2-adrenoceptor/Gs protein/adenylyl cyclase axis. More recently, we have shown that ß2-adrenoceptor agonists also increase extracellular 3',5'-cAMP levels in isolated rat trachea, which leads to contraction of airway smooth muscle. In many other tissues, extracellular 3',5'-cAMP is metabolized by ectoenzymes to extracellular adenosine, a catabolic pathway that has never been addressed in airways. In order to evaluate the possible extracellular degradation of 3',5'-cAMP into 5'-AMP and adenosine in the airways, isolated rat tracheas were incubated with exogenous 3',5'-cAMP and the amount of 5'-AMP, adenosine and inosine (adenosine metabolite) produced was evaluated using ultraperformance liquid chromatography-tandem mass spectrometry. Incubation of tracheal tissue with 3',5'-cAMP induced a time- and concentration-dependent increase in 5'-AMP, adenosine and inosine in the medium. Importantly, IBMX (non-selective phosphodiesterase (PDE) inhibitor) and DPSPX (selective ecto-PDE inhibitor) reduced the extracellular conversion of 3',5'-cAMP to 5'-AMP. In addition, incubation of 3',5'-cAMP in the presence of AMPCP (inhibitor of ecto-5'-nucleotidase) increased extracellular levels of 5'-AMP while drastically reducing extracellular levels of adenosine and inosine. These results indicate that airways express an extracellular enzymatic system (ecto-phosphodiesterase, ecto-5'-nucleotidase and adenosine deaminase) that sequentially converts 3',5'-cAMP into 5'-AMP, adenosine and inosine. The observation that extracellular 3',5'-cAMP is a source of interstitial adenosine supports the idea that the extrusion and extracellular metabolism of 3',5'-cAMP has a role in respiratory physiology and pathophysiology.
Assuntos
Adenosina/metabolismo , AMP Cíclico/metabolismo , Líquido Extracelular/metabolismo , Músculo Liso/metabolismo , Traqueia/metabolismo , Animais , Masculino , Técnicas de Cultura de Órgãos , Ratos , Ratos WistarRESUMO
Global warming is affecting biodiversity; however, the extent to which animal reproductive processes respond to predicted temperature increments remains largely unexplored. The thermal environment has a pronounced impact on metabolic rates of ectotherms; therefore, an interesting question to assess is whether temperature increase might affect specific reproductive mechanisms like sperm performance in ectotherms. Moreover, in many species, oviductal fluid (OF) is known to regulate and maintain sperm quality; however, the role of OF in relation to the effects of high temperature on sperm remains unclear. Our aim was to experimentally test the effect of increased temperature on sperm velocity, swimming path and percentage of motility in neutral conditions at ejaculation (without OF) and in female's reproductive tract fluid (with OF), in a social ectotherm lizard model, Tropidurus spinulosus, which has specific thermal requirements for reproduction. Our results suggest that a rising temperature associated with global warming (+4°C) affects negatively sperm dynamics and survival. However, OF ameliorated the harmful effects of high temperature. This is an important point, as this study is the first to have tested the role of OF in preserving sperm from a warmer pre-fertilization environment. These results contribute to our understanding of how thermal environment changes might affect post-copulatory reproductive mechanisms. This article has an associated First Person interview with the first author of the paper.
Assuntos
Ectoderma/fisiologia , Líquido Extracelular/metabolismo , Oviductos/fisiologia , Espermatozoides/fisiologia , Temperatura , Adaptação Fisiológica , Animais , Feminino , Lagartos/fisiologia , Masculino , Motilidade dos EspermatozoidesRESUMO
Protein malnutrition is a risk factor for developing visceral leishmaniasis. Because we previously demonstrated that protein malnutrition and infection with Leishmania infantum disrupts the splenic microarchitecture in BALB/c mice, alters T cell-subsets and increases splenic parasite load, we hypothesize that splenic microenvironment is precociously compromised in infected animals that suffered a preceding malnutrition. To evaluate this, we characterized the abundance of proteins secreted in the splenic interstitial fluid (IF) using an iTRAQ-based quantitative proteomics approach. In addition, local levels of pro-inflammatory and proliferation molecules were analyzed. Whereas well-nourished infected animals showed increased IL-1ß and IL-2 levels, malnourished-infected mice displayed significant reduction of these cytokines. Remarkably, a two-weeks infection with L. infantum already modified protein abundance in the splenic IF of well-nourished mice, but malnourished animals failed to respond to infection in the same fashion. Malnutrition induced significant reduction of chemotactic and pro-inflammatory molecules as well as of proteins involved in nucleic acid and amino acid metabolism, indicating an impaired proliferative microenvironment. Accordingly, a significant decrease in Ki67 expression was observed, suggesting that splenocyte proliferation is compromised in malnourished animals. Together, our results show that malnutrition compromises the splenic microenvironment and alters the immune response to the parasite in malnourished individuals. SIGNIFICANCE: Protein malnutrition is recognized as an important epidemiological risk factor for developing visceral leishmaniasis (VL). Locally secreted factors present in the interstitial fluid have important roles in initiating immune responses and in regulating fluid volume during inflammation. However, the regulation of secreted factors under pathological conditions such as malnutrition and infection are widely unknown. To analyze how protein malnutrition alters secreted proteins involved in the immune response to L. infantum infection we evaluated the proteomic profile of the interstitial fluid of the spleen in malnourished BALB/c mice infected with L. infantum. Our work revealed new elements that contribute to the understanding of the immunopathological events in the spleen of malnourished animals infected with L. infantum and opens new pathways for consideration of other aspects that could improve VL treatment in malnourished individuals.
Assuntos
Proliferação de Células , Líquido Extracelular/metabolismo , Perfilação da Expressão Gênica , Leishmania infantum/metabolismo , Leishmaniose Visceral/metabolismo , Desnutrição/metabolismo , Proteômica , Baço/metabolismo , Animais , Líquido Extracelular/parasitologia , Inflamação/metabolismo , Inflamação/parasitologia , Inflamação/patologia , Leishmaniose Visceral/patologia , Masculino , Desnutrição/parasitologia , Desnutrição/patologia , Camundongos , Camundongos Endogâmicos BALB C , Baço/parasitologia , Baço/patologiaRESUMO
Detrimental effects of malnutrition on immune responses to pathogens have long been recognized and it is considered a main risk factor for various infectious diseases, including visceral leishmaniasis (VL). Thymus is a target of both malnutrition and infection, but its role in the immune response to Leishmania infantum in malnourished individuals is barely studied. Because we previously observed thymic atrophy and significant reduction in cellularity and chemokine levels in malnourished mice infected with L. infantum, we postulated that the thymic microenvironment is severely compromised in those animals. To test this, we analyzed the microarchitecture of the organ and measured the protein abundance in its interstitial space in malnourished BALB/c mice infected or not with L. infantum. Malnourished-infected animals exhibited a significant reduction of the thymic cortex:medulla ratio and altered abundance of proteins secreted in the thymic interstitial fluid. Eighty-one percent of identified proteins are secreted by exosomes and malnourished-infected mice showed significant decrease in exosomal proteins, suggesting that exosomal carrier system, and therefore intrathymic communication, is dysregulated in those animals. Malnourished-infected mice also exhibited a significant increase in the abundance of proteins involved in lipid metabolism and tricarboxylic acid cycle, suggestive of a non-proliferative microenvironment. Accordingly, flow cytometry analysis revealed decreased proliferation of single positive and double positive T cells in those animals. Together, the reduced cortical area, decreased proliferation, and altered protein abundance suggest a dysfunctional thymic microenvironment where T cell migration, proliferation, and maturation are compromised, contributing for the thymic atrophy observed in malnourished animals. All these alterations could affect the control of the local and systemic infection, resulting in an impaired response to L. infantum infection.
Assuntos
Interações Hospedeiro-Patógeno/imunologia , Leishmania infantum/imunologia , Leishmaniose Visceral/imunologia , Desnutrição/imunologia , Linfócitos T/imunologia , Timo/imunologia , Animais , Transporte Biológico , Movimento Celular , Proliferação de Células , Ciclo do Ácido Cítrico/genética , Ciclo do Ácido Cítrico/imunologia , Exossomos/imunologia , Exossomos/metabolismo , Exossomos/parasitologia , Líquido Extracelular/imunologia , Líquido Extracelular/metabolismo , Líquido Extracelular/parasitologia , Galectina 1/genética , Galectina 1/imunologia , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Imunidade Inata , Leishmania infantum/crescimento & desenvolvimento , Leishmaniose Visceral/genética , Leishmaniose Visceral/metabolismo , Leishmaniose Visceral/parasitologia , Metabolismo dos Lipídeos , Masculino , Desnutrição/genética , Desnutrição/metabolismo , Desnutrição/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Plasminogênio/genética , Plasminogênio/imunologia , Proteoma/genética , Proteoma/imunologia , Linfócitos T/parasitologia , Timo/metabolismo , Timo/parasitologiaRESUMO
Glutamate release in response to a hypertonic stimulus is a well described phenomenon in the hypothalamus. Evidence suggests that hypothalamic glial cells release glutamate into the extracellular environment in hypertonic conditions. In the current study, we described autocrine regulation of adenosine on glutamate release induced by Na+hypertonicity in hypothalamic glial cell cultures. We showed that glial cells cultured from the cerebral cortex did not release glutamate or adenosine under hypertonic conditions. The findings suggest that the hypothalamus has specialized glial cells, which are responsive to osmotic variations. Stimulation or inhibition of adenosine A1 receptors modulates extracellular glutamate levels in hypothalamic glial cell cultures under hypertonic stimulation. Our results extend previous observations regarding the role of glial cells in the control of hypothalamic physiology. They further demonstrate for the first time that hypothalamic glial cells regulate Na+-hypertonicity-induced glutamate release by activation of adenosine A1 receptors via adenosine release.
Assuntos
Ácido Glutâmico/metabolismo , Hipotálamo/metabolismo , Neuroglia/metabolismo , Receptor A1 de Adenosina/fisiologia , Cloreto de Sódio/farmacologia , Adenosina/farmacologia , Agonistas do Receptor A1 de Adenosina/farmacologia , Animais , Animais Recém-Nascidos , Células Cultivadas , Relação Dose-Resposta a Droga , Líquido Extracelular/efeitos dos fármacos , Líquido Extracelular/metabolismo , Hipotálamo/efeitos dos fármacos , Neuroglia/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Abstract Background: To date there are no specific classification criteria for childhood-onset systemic lupus erythematosus (cSLE). This study aims to compare the performance among the American College of Rheumatology (ACR) 1997, the Systemic Lupus International Collaborating Clinics criteria (SLICC) and the new European League Against Rheumatism (EULAR)/ACR criteria, in a cSLE cohort. Methods: We conducted a medical chart review study of cSLE cases and controls with defined rheumatic diseases, both ANA positive, to establish each ACR1997, SLICC and EULAR/ACR criterion fulfilled, at first visit and 1-year-follow-up. Results: Study population included 122 cSLE cases and 89 controls. At first visit, SLICC criteria had higher sensitivity than ACR 1997 (89.3% versus 70.5%, p < 0.001), but similar specificity (80.9% versus 83.2%, p = 0.791), however performance was not statistically different at 1-year-follow-up. SLICC better scored in specificity compared to EULAR/ACR score ≥ 10 at first visit (80.9% versus 67.4%, p = 0.008) and at 1-year (76.4% versus 58.4%, p = 0.001), although sensitivities were similar. EULAR/ACR criteria score ≥ 10 exhibited higher sensitivity than ACR 1997 (87.7% versus 70.5%, p < 0.001) at first visit, but comparable at 1-year, whereas specificity was lower at first visit (67.4% versus 83.2%, p = 0.004) and 1-year (58.4% versus 76.4%, p = 0.002). A EULAR/ACR score ≥ 13 against a score ≥ 10, resulted in higher specificity, positive predictive value, and cut-off point accuracy. Compared to SLICC, a EULAR/ACR score ≥ 13 resulted in lower sensitivity at first visit (76.2% versus 89.3%, p < 0.001) and 1-year (91% versus 97.5%, p = 0.008), but similar specificities at both assessments. When compared to ACR 1997, a EULAR/ACR total score ≥ 13, resulted in no differences in sensitivity and specificity at both observation periods. Conclusions: In this cSLE population, SLICC criteria better scored at first visit and 1-year-follow-up. The adoption of a EULAR/ACR total score ≥ 13 in this study, against the initially proposed ≥10 score, was most appropriate to classify cSLE. Further studies are necessary to address if SLICC criteria might allow fulfillment of cSLE classification earlier in disease course and may be more inclusive of cSLE subjects for clinical studies.
Assuntos
Animais , Humanos , Encéfalo/metabolismo , Preparações Farmacêuticas/metabolismo , Barreira Hematoencefálica/metabolismo , Distribuição Tecidual/fisiologia , Modelos Teóricos , Aracnoide-Máter/efeitos dos fármacos , Aracnoide-Máter/metabolismo , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Encéfalo/efeitos dos fármacos , Preparações Farmacêuticas/administração & dosagem , Barreira Hematoencefálica/efeitos dos fármacos , Distribuição Tecidual/efeitos dos fármacos , Líquido Extracelular/efeitos dos fármacos , Líquido Extracelular/metabolismoRESUMO
Hydrogen peroxide (H2O2) is a messenger involved in both damaging neuroinflammatory responses and physiological cell communication. The ventrolateral medulla, which regulates several vital functions including breathing and blood pressure, is highly influenced by hydrogen peroxide, whose extracellular levels could be determined by hypoxia and microglial activity, both of which modulate ventrolateral medulla function. Therefore, in this study we aimed to test whether different patterns of hypoxia and/or putative microglial modulators change extracellular hydrogen peroxide in the ventrolateral medulla by using an enzymatic reactor online sensing procedure specifically designed for this purpose. With this new technique, we detected extracellular levels of hydrogen peroxide in the ventrolateral medulla in vitro, which spontaneously fluctuated. These fluctuations are reduced by minocycline, a putative microglial inhibitor, and by the microglial toxin liposomal clodronate. Suitably, lipopolysaccharide increases extracellular hydrogen peroxide, while minocycline and liposomal clodronate reduce this increase. Application of blue light to slices with microglia expressing channelrhodopsin-2 also increases extracellular hydrogen peroxide. Moreover, long-lasting and intermittent hypoxia (as well as subsequent reoxygenation) increase extracellular hydrogen peroxide to similar levels, which is partially prevented by minocycline. The effect of long-lasting hypoxia was reproduced in vivo. Overall, our data show that changes in oxygen concentration, and possibly microglial function, modulate extracellular H2O2 levels in the ventrolateral medulla, which could influence the function of this neural circuit under normal and pathological conditions related to inflammation and/or hypoxia.
Assuntos
Líquido Extracelular/metabolismo , Peróxido de Hidrogênio/metabolismo , Hipóxia/fisiopatologia , Bulbo/citologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/genética , Animais , Receptor 1 de Quimiocina CX3C/genética , Receptor 1 de Quimiocina CX3C/metabolismo , Channelrhodopsins/genética , Channelrhodopsins/metabolismo , Líquido Extracelular/efeitos dos fármacos , Hipóxia/tratamento farmacológico , Lidocaína/farmacologia , Lipopolissacarídeos/farmacologia , Masculino , Camundongos , Camundongos Transgênicos , Microglia/efeitos dos fármacos , Microglia/fisiologia , Minociclina/uso terapêutico , Oxigênio/farmacologia , Técnicas de Patch-Clamp , RNA não Traduzido/genética , RNA não Traduzido/metabolismo , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC50â¯=â¯46â¯nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.
Assuntos
Anafilaxia/metabolismo , Cálcio/metabolismo , Mastócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de IgE/antagonistas & inibidores , Xantonas/farmacologia , Animais , Degranulação Celular/efeitos dos fármacos , Degranulação Celular/fisiologia , Células Cultivadas , Relação Dose-Resposta a Droga , Líquido Extracelular/efeitos dos fármacos , Líquido Extracelular/metabolismo , Masculino , Mastócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Difração de Raios X , Xantonas/isolamento & purificaçãoRESUMO
The mesocorticolimbic circuit projects to the prefrontal cortex, hippocampus, amygdala, and nucleus accumbens, among others, and it originates in the dopaminergic neurons of the ventral tegmental area (VTA). The VTA receives glutamatergic inputs from the prefrontal cortex and several subcortical regions. The glutamate released activates dopaminergic neurons and its action depends on the activation of ionotropic and metabotropic glutamate receptors. VTA dopaminergic neurons release dopamine (DA) from axon terminals in the innervated regions and somatodendritically in the VTA itself. DA release in the VTA is directly correlated with the activity of dopaminergic neurons. We hypothesized that metabotropic glutamate 5 receptors (mGlu5) directly regulate the activity of VTA dopaminergic neurons. To test this hypothesis, the extracellular levels of VTA DA and glutamate were studied by in-vivo microdialysis after an intra-VTA perfusion of (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG), selective mGlu5 agonist. We observed that CHPG induced a significant increase in VTA DA and glutamate extracellular levels. To determine whether the effect of CHPG on DA levels is because of the increase in glutamate release, we perfused kynurenic acid, an ionotropic glutamate receptor antagonist, through the probe. Our results showed that kynurenic acid did not block the ability of CHPG to cause DA release. Thus, our results suggest that CHPG acts directly on mGlu5 in dopaminergic neurons to induce the release of DA.
Assuntos
Dopamina/metabolismo , Líquido Extracelular/metabolismo , Receptor de Glutamato Metabotrópico 5/metabolismo , Área Tegmentar Ventral/metabolismo , Animais , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Líquido Extracelular/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Glicina/análogos & derivados , Glicina/farmacologia , Ácido Cinurênico/farmacologia , Masculino , Microdiálise , Fenilacetatos/farmacologia , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Tiazóis/farmacologia , Área Tegmentar Ventral/efeitos dos fármacosRESUMO
Intramuscular acidosis is a contributing factor to fatigue during high-intensity exercise. Many nutritional strategies aiming to increase intra- and extracellular buffering capacity have been investigated. Among these, supplementation of beta-alanine (~3-6.4 g/day for 4 weeks or longer), the rate-limiting factor to the intramuscular synthesis of carnosine (i.e. an intracellular buffer), has been shown to result in positive effects on exercise performance in which acidosis is a contributing factor to fatigue. Furthermore, sodium bicarbonate, sodium citrate and sodium/calcium lactate supplementation have been employed in an attempt to increase the extracellular buffering capacity. Although all attempts have increased blood bicarbonate concentrations, evidence indicates that sodium bicarbonate (0.3 g/kg body mass) is the most effective in improving high-intensity exercise performance. The evidence supporting the ergogenic effects of sodium citrate and lactate remain weak. These nutritional strategies are not without side effects, as gastrointestinal distress is often associated with the effective doses of sodium bicarbonate, sodium citrate and calcium lactate. Similarly, paresthesia (i.e. tingling sensation of the skin) is currently the only known side effect associated with beta-alanine supplementation, and it is caused by the acute elevation in plasma beta-alanine concentration after a single dose of beta-alanine. Finally, the co-supplementation of beta-alanine and sodium bicarbonate may result in additive ergogenic gains during high-intensity exercise, although studies are required to investigate this combination in a wide range of sports.