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ABSTRACT: There is evidence to suggest that the hypothermia observed in the most severe cases of systemic inflammation or sepsis is a regulated response with potential adaptive value, but the mechanisms involved are poorly understood. Here, we investigated the interplay between brain oxygenation (assessed by tissue P o2 ) and the development of hypothermia in unanesthetized rats challenged with a hypotension-inducing dose of bacterial LPS (1 mg/kg i.v.). At an ambient temperature of 22°C, oxygen consumption (VÌO 2 ) began to fall only a few minutes after the LPS injection, and this suppression in metabolic rate preceded the decrease in core temperature. No reduction in brain P o2 was observed prior to the development of the hypometabolic, hypothermic response, ruling out the possibility that brain hypoxia served as a trigger for hypothermia in this model. Brain P o2 was even increased. Such an improvement in brain oxygenation could reflect either an increased O 2 delivery or a decreased O 2 consumption. The former explanation seems unlikely because blood flow (cardiac output) was being progressively decreased during the recording period. On the other hand, the decrease in VÌO 2 usually preceded the rise in P o2 , and an inverse correlation between VÌO 2 and brain P o2 was consistently observed. These findings do not support the existence of a closed-loop feedback relationship between brain oxygenation and hypothermia in systemic inflammation. The data are consistent with a feedforward mechanism in which hypothermia is triggered (possibly by cryogenic inflammatory mediators) in anticipation of changes in brain oxygenation to prevent the development of tissue hypoxia.
Assuntos
Encéfalo , Hipotermia , Consumo de Oxigênio , Oxigênio , Choque Séptico , Animais , Encéfalo/metabolismo , Ratos , Masculino , Choque Séptico/metabolismo , Choque Séptico/fisiopatologia , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Hipotermia/metabolismo , Hipotermia/fisiopatologia , Lipopolissacarídeos , Ratos WistarRESUMO
Hepatocellular carcinoma (HCC) markedly enhances liver secretion of fibroblast growth factor 21 (FGF-21), a hepatokine that increases brown and subcutaneous inguinal white adipose tissues (BAT and iWAT, respectively) uncoupling protein 1 (UCP-1) content, thermogenesis and energy expenditure. Herein, we tested the hypothesis that an enhanced BAT and iWAT UCP-1-mediated thermogenesis induced by high levels of FGF-21 is involved in HCC-associated catabolic state and fat mass reduction. For this, we evaluated body weight and composition, liver mass and morphology, serum and tissue levels of FGF-21, BAT and iWAT UCP-1 content, and thermogenic capacity in mice with Pten deletion in hepatocytes that display a well-defined progression from steatosis to steatohepatitis (NASH) and HCC upon aging. Hepatocyte Pten deficiency promoted a progressive increase in liver lipid deposition, mass, and inflammation, culminating with NASH at 24 weeks and hepatomegaly and HCC at 48 weeks of age. NASH and HCC were associated with elevated liver and serum FGF-21 content and iWAT UCP-1 expression (browning), but reduced serum insulin, leptin, and adiponectin levels and BAT UCP-1 content and expression of sympathetically regulated gene glycerol kinase (GyK), lipoprotein lipase (LPL), and fatty acid transporter protein 1 (FATP-1), which altogether resulted in an impaired whole-body thermogenic capacity in response to CL-316,243. In conclusion, FGF-21 pro-thermogenic actions in BAT are context-dependent, not occurring in NASH and HCC, and UCP-1-mediated thermogenesis is not a major energy-expending process involved in the catabolic state associated with HCC induced by Pten deletion in hepatocytes.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Hepatopatia Gordurosa não Alcoólica , Camundongos , Animais , Carcinoma Hepatocelular/metabolismo , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo , Tecido Adiposo Marrom/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Neoplasias Hepáticas/metabolismo , Hepatócitos , Termogênese/genética , Tecido Adiposo Branco/metabolismoRESUMO
Uncontrolled vasodilation is known to account for hypotension in the advanced stages of sepsis and other systemic inflammatory conditions, but the mechanisms of hypotension in earlier stages of such conditions are not clear. By monitoring hemodynamics with the highest temporal resolution in unanesthetized rats, in combination with ex-vivo assessment of vascular function, we found that early development of hypotension following injection of bacterial lipopolysaccharide is brought about by a fall in vascular resistance when arterioles are still fully responsive to vasoactive agents. This approach further uncovered that the early development of hypotension stabilized blood flow. We thus hypothesized that prioritization of the local mechanisms of blood flow regulation (tissue autoregulation) over the brain-driven mechanisms of pressure regulation (baroreflex) underscored the early development of hypotension in this model. Consistent with this hypothesis, an assessment of squared coherence and partial-directed coherence revealed that, at the onset of hypotension, the flow-pressure relationship was strengthened at frequencies (<0.2â Hz) known to be associated with autoregulation. The autoregulatory escape to phenylephrine-induced vasoconstriction, another proxy of autoregulation, was also strengthened in this phase. The competitive demand that drives prioritization of flow over pressure regulation could be edema-associated hypovolemia, as this became detectable at the onset of hypotension. Accordingly, blood transfusion aimed at preventing hypovolemia brought the autoregulation proxies back to normal and prevented the fall in vascular resistance. This novel hypothesis opens a new avenue of investigation into the mechanisms that can drive hypotension in systemic inflammation.
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Nanoemulsions modified with chitosan (NE-Q) or hyaluronic acid (NE-HA), developed for intraductal administration of piplartine (piperlongumine) and local breast cancer treatment, were evaluated for cytotoxic effects in vitro in 2D and 3D breast cancer models and in vivo in a chemically induced carcinogenesis model. Droplet size was lower than 100 nm, and zeta potential varied from +17.9 to -25.5 mV for NE-Q and NE-HA, respectively. Piplartine nanoencapsulation reduced its IC50 up to 3.6-fold in T-47D and MCF-7 monolayers without differences between NE-Q and NE-HA, and up to 6.6-fold in cancer spheroids. Cytotoxicity improvement may result from a more efficient NE-mediated delivery, as suggested by stronger fluorescent staining of cells and spheroids. In 1-methyl-1-nitrosourea -induced breast cancer models, intraductal administration of piplartine-loaded NE-HA inhibited breast tumor development and histological alterations. These results support the potential applicability of piplartine-loaded NE-HA for intraductal treatment of breast cancer.
Assuntos
Neoplasias da Mama , Quitosana , Nanopartículas , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Quitosana/farmacologia , Feminino , Humanos , Ácido Hialurônico/farmacologia , PiperidonasRESUMO
Deletion of mechanistic target of rapamycin complex 2 (mTORC2) essential component rapamycin insensitive companion of mTOR (Rictor) by a Cre recombinase under control of the broad, nonadipocyte-specific aP2/FABP4 promoter impairs thermoregulation and brown adipose tissue (BAT) glucose uptake on acute cold exposure. We investigated herein whether adipocyte-specific mTORC2 deficiency affects BAT and inguinal white adipose tissue (iWAT) signaling, metabolism, and thermogenesis in cold-acclimated mice. For this, 8-wk-old male mice bearing Rictor deletion and therefore mTORC2 deficiency in adipocytes (adiponectin-Cre) and littermates controls were either kept at thermoneutrality (30 ± 1°C) or cold-acclimated (10 ± 1°C) for 14 days and evaluated for BAT and iWAT signaling, metabolism, and thermogenesis. Cold acclimation inhibited mTORC2 in BAT and iWAT, but its residual activity is still required for the cold-induced increases in BAT adipocyte number, total UCP-1 content and mRNA levels of proliferation markers Ki67 and cyclin 1 D, and de novo lipogenesis enzymes ATP-citrate lyase and acetyl-CoA carboxylase. In iWAT, mTORC2 residual activity is partially required for the cold-induced increases in multilocular adipocytes, mitochondrial mass, and uncoupling protein 1 (UCP-1) content. Conversely, BAT mTORC1 activity and BAT and iWAT glucose uptake were upregulated by cold independently of mTORC2. Noteworthy, the impairment in BAT and iWAT total UCP-1 content and thermogenic capacity induced by adipocyte mTORC2 deficiency had no major impact on whole body energy expenditure in cold-acclimated mice due to a compensatory activation of muscle shivering. In conclusion, adipocyte mTORC2 deficiency impairs, through different mechanisms, BAT and iWAT total UCP-1 content and thermogenic capacity in cold-acclimated mice, without affecting glucose uptake and whole body energy expenditure.NEW & NOTEWORTHY BAT and iWAT mTORC2 is inhibited by cold acclimation, but its residual activity is required for cold-induced increases in total UCP-1 content and thermogenic capacity, but not glucose uptake and mTORC1 activity. The impaired BAT and iWAT total UCP-1 content and thermogenic capacity induced by adipocyte mTORC2 deficiency are compensated by activation of muscle shivering in cold-acclimated mice.
Assuntos
Aclimatação/fisiologia , Adipócitos/metabolismo , Tecido Adiposo Marrom/fisiologia , Tecido Adiposo Branco/fisiologia , Metabolismo Energético/fisiologia , Glucose/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/deficiência , Termogênese/genética , Animais , Temperatura Baixa , Deleção de Genes , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/fisiologia , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Camundongos , Camundongos Endogâmicos C57BL , Proteína Desacopladora 1RESUMO
Although hypothermia has received substantial attention as an indicator of severity in anaphylaxis, it has been neglected from the perspective of whether it could act as a disease-modifying factor in this condition. Here, the impact of naturally occurring (spontaneous) hypothermia on anaphylaxis was evaluated in a murine model of ovalbumin (OVA)-induced allergy. Nonextreme changes in the ambient temperature (Ta) were used to modulate the magnitude of spontaneous hypothermia. At a Ta of 24°C, challenge with OVA intraperitoneally or intravenously resulted in a rapid, transient fall in body core temperature, which reached its nadir 4-6°C below baseline in 30 min. This hypothermic response was largely attenuated when the mice were kept at a Ta of 34°C. The Ta-dependent attenuation of hypothermia resulted in a survival rate of only 30%, as opposed to survival of 100% in the condition that favored the development of hypothermia. The protective effect of hypothermia did not involve changes in the rate of mast cell degranulation, as assessed by the concentration of mast cell protease-1 in bodily fluids. On the other hand, hypothermia improved oxygenation of the brain and kidneys, as indicated by higher NAD+/NADH ratios. Therefore, it is plausible to propose that naturally occurring hypothermia makes organs more resistant to the anaphylactic insult.
Assuntos
Anafilaxia/fisiopatologia , Hipotermia/fisiopatologia , Anafilaxia/induzido quimicamente , Anafilaxia/complicações , Anafilaxia/mortalidade , Animais , Líquidos Corporais/enzimologia , Química Encefálica , Degranulação Celular , Hipóxia Celular , Quimases/análise , Temperatura Baixa , Feminino , Hipotermia/etiologia , Rim/química , Mastócitos/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , NAD/análise , Ovalbumina/toxicidade , Oxigênio/análiseRESUMO
Production of the proinflammatory cytokine tumor necrosis factor (TNF) must be precisely regulated for effective host immunity without the induction of collateral tissue damage. Here, we showed that TNF production was driven by a spleen-liver axis in a rat model of systemic inflammation induced by bacterial lipopolysaccharide (LPS). Analysis of cytokine expression and secretion in combination with splenectomy and hepatectomy revealed that the spleen generated not only TNF but also factors that enhanced TNF production by the liver, the latter of which accounted for nearly half of the TNF secreted into the circulation. Using mass spectrometry-based lipidomics, we identified leukotriene B4 (LTB4) as a candidate blood-borne messenger in this spleen-liver axis. LTB4 was essential for spleen-liver communication in vivo, as well as for humoral signaling between splenic macrophages and Kupffer cells in vitro. LPS stimulated the splenic macrophages to secrete LTB4, which primed Kupffer cells to secrete more TNF in response to LPS in a manner dependent on LTB4 receptors. These findings provide a framework to understand how systemic inflammation can be regulated at the level of interorgan communication.
Assuntos
Leucotrieno B4 , Baço , Animais , Inflamação , Lipopolissacarídeos/toxicidade , Fígado , Ratos , Fator de Necrose Tumoral alfaRESUMO
KEY POINTS: The costs associated with immune and thermal responses may exceed the benefits to the host during severe inflammation. In this case, regulated hypothermia instead of fever can occur in rodents as a beneficial strategy to conserve energy for vital functions with consequent tissue protection and hypoxia prevention. We tested the hypothesis that this phenomenon is not exclusive to mammals, but extends to the other endothermic group, birds. A decrease in metabolic rate without any failure in mitochondrial respiration, nor oxygen delivery, is the main evidence supporting the regulated nature of endotoxin-induced hypothermia in chicks. Thermolytic mechanisms such as tachypnea and cutaneous vasodilatation can also be recruited to facilitate body temperature decrease under lipopolysaccharide treatment, especially in the cold. Our findings bring a new perspective for evolutionary medicine studies on energy trade-off in host defence because regulated hypothermia may be a phenomenon spread among vertebrates facing a severe immune challenge. ABSTRACT: A switch from fever to regulated hypothermia can occur in mammals under circumstances of reduced physiological fitness (e.g. sepsis) to direct energy to defend vital systems. Birds in which the cost to resist a pathogen is additive to the highest metabolic rate and body temperature (Tb ) among vertebrates may also benefit from regulated hypothermia during systemic inflammation. Here, we show that the decrease in Tb observed during an immune challenge in birds is a regulated hypothermia, and not a result of metabolic failure. We investigated O2 consumption (thermogenesis index), ventilation (respiratory heat loss), skin temperature (sensible heat loss) and muscle mitochondrial respiration (thermogenic tissue) during Tb fall in chicken chicks challenged with endotoxin [lipopolysaccharide (LPS)]. Chicks injected with LPS were also tested regarding the capacity to raise O2 consumption to meet an increased demand driven by 2,4-dinitrophenol. LPS decreased Tb and the metabolic rate of chicks without affecting muscle uncoupled, coupled and non-coupled mitochondrial respiration. LPS-challenged chicks were indeed capable of increasing metabolic rate in response to 2,4-dinitrophenol, indicating no O2 delivery limitation. Additionally, chicks did not attempt to prevent Tb from falling during hypothermia but, instead, activated cutaneous and respiratory thermolytic mechanisms, providing an additional cooling force. These data provide the first evidence of the regulated nature of the hypothermic response to endotoxin in birds. Therefore, it changes the current understanding of bird's thermoregulation during severe inflammation, indicating that regulated hypothermia is either a convergent trait for endotherms or a conserved response among vertebrates, which adds a new perspective for evolutionary medicine research.
Assuntos
Hipotermia , Animais , Temperatura Corporal , Regulação da Temperatura Corporal , Galinhas , Endotoxinas/toxicidadeRESUMO
Life-threatening infections (sepsis) are usually associated with co-morbidities, among which obesity deserves attention. Here, we evaluated whether and how obesity affects the switch from fever to hypothermia that occurs in the most severe cases of sepsis, which is thought to provide physiological support for a change in host defense strategy from resistance to tolerance. Obesity was induced by keeping rats on a high-fat diet for 32-34 weeks. The hypothermia induced by a high dose of bacterial lipopolysaccharide (LPS, 300 µg/animal, i.a.) was attenuated in the obese rats, as compared to their low-fat diet counterparts. Surprisingly, such attenuation occurred in spite of an enhancement in the circulating level of TNF-α, the most renowned mediator of LPS-induced hypothermia. Hence, it seems that factors counteracting not the production, but rather the action of TNF-α are at play in rats with diet-induced obesity. One of these factors might be IL-1ß, a febrigenic mediator that also had its circulating levels augmented in the obese rats challenged with LPS. Taken together with previous reports of diet-induced obesity enhancing the fever induced by lower doses of LPS, the results of the present study indicate that obesity biases host defense toward a fever/resistance strategy, in lieu of a hypothermia/tolerance strategy.
Assuntos
Antipiréticos/efeitos adversos , Infecções por Coronavirus , Cultura , Erros de Diagnóstico , Uso Indevido de Medicamentos , Febre , Pandemias , Pneumonia Viral , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/imunologia , Antropologia Médica , Antipiréticos/administração & dosagem , Betacoronavirus/isolamento & purificação , COVID-19 , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/fisiopatologia , Erros de Diagnóstico/efeitos adversos , Erros de Diagnóstico/prevenção & controle , Progressão da Doença , Uso Indevido de Medicamentos/efeitos adversos , Uso Indevido de Medicamentos/prevenção & controle , Febre/tratamento farmacológico , Febre/etiologia , Febre/psicologia , Humanos , Imunidade/fisiologia , Pneumonia Viral/diagnóstico , Pneumonia Viral/imunologia , Pneumonia Viral/fisiopatologia , SARS-CoV-2RESUMO
The mechanisms by which obesity may alter immune responses to pathogens are poorly understood. The present study assessed whether the intrinsic responsiveness of resident macrophages to bacterial lipopolysaccharide (LPS) is reprogrammed in high-fat diet (HFD)-induced obesity. Macrophages from adipose tissue, lung alveoli, and the peritoneal cavity were extracted from obese rats on a HFD or from their lean counterparts, and subsequently studied in culture under identical conditions. CD45+/CD68+ cells (macrophages) were abundant in all cultures, and became the main producers of TNF-α upon LPS stimulation. But although all macrophage subpopulations responded to LPS with an M1-like profile of cytokine secretion, the TNF-α/IL-10 ratio was the lowest in adipose tissue macrophages, the highest in alveolar macrophages, and intermediary in peritoneal macrophages. What is more, diet exerted qualitatively distinct effects on the cytokine responses to LPS, with obesity switching adipose tissue macrophages to a more pro-inflammatory program and peritoneal macrophages to a less pro-inflammatory program, while not affecting alveolar macrophages. Such reprogramming was not associated with changes in the inflammasome-dependent secretion of IL-1ß. The study further shows that the effects of diet on TNF-α/IL-10 ratios were linked to distinct patterns of NF-κB accumulation in the nucleus: while RelA was the NF-κB subunit most impacted by obesity in adipose tissue macrophages, cRel was the subunit affected in peritoneal macrophages. It is concluded that obesity causes dissimilar, site-specific changes in the responsiveness of resident macrophages to bacterial LPS. Such plasticity opens new avenues of investigation into the mechanisms linking obesity to pathogen-induced immune responses.
Assuntos
Lipopolissacarídeos/farmacologia , Macrófagos/imunologia , Obesidade/imunologia , Tecido Adiposo/citologia , Tecido Adiposo/imunologia , Animais , Citocinas/imunologia , Masculino , NF-kappa B/imunologia , Cavidade Peritoneal/citologia , Alvéolos Pulmonares/citologia , Alvéolos Pulmonares/imunologia , Ratos WistarRESUMO
As a new strategy for treatment of ductal carcinoma in situ, biocompatible and bioadhesive nanoemulsions for intraductal administration of the cytotoxic agent piplartine (piperlongumine) were optimized in this study. To confer bioadhesive properties, the nanoemulsion was modified with chitosan or hyaluronic acid. Tricaprylin was selected as the nanoemulsion non-polar phase due to its ability to dissolve larger drug amounts compared to isopropyl myristate and monocaprylin. Use of phosphatidylcholine as sole surfactant did not result in a homogeneous nanoemulsion, while its association with polysorbate 80 and glycerol (in a surfactant blend) led to the formation of nanoemulsions with droplet size of 76.5⯱â¯1.2â¯nm. Heating the aqueous phase to 50⯰C enabled sonication time reduction from 20 to 10â¯min. Inclusion of either chitosan or hyaluronic acid resulted in nanoemulsions with similar in vitro bioadhesive potential, and comparable ability to prolong mammary tissue retention (to 120â¯h) in vivo without causing undesirable histological alterations. Piplartine was stable in both nanoemulsions for 60â¯days; however, the size of loaded NE-HA was maintained at a similar range for longer periods of time, suggesting that this nanoemulsion may be a stronger candidate for intraductal delivery.
Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Dioxolanos/administração & dosagem , Glândulas Mamárias Animais/metabolismo , Nanopartículas/administração & dosagem , Piperidonas/administração & dosagem , Adesividade , Animais , Antineoplásicos Fitogênicos/química , Galinhas , Quitosana/administração & dosagem , Quitosana/química , Membrana Corioalantoide/efeitos dos fármacos , Dioxolanos/química , Vias de Administração de Medicamentos , Emulsões , Feminino , Glicerol/administração & dosagem , Glicerol/química , Ácido Hialurônico/administração & dosagem , Ácido Hialurônico/química , Nanopartículas/química , Fosfatidilcolinas/administração & dosagem , Fosfatidilcolinas/química , Piperidonas/química , Polissorbatos/administração & dosagem , Polissorbatos/química , Ratos Wistar , Pele/química , SuínosRESUMO
BACKGROUND: During the feeding process, the mouthparts of hematophagous mosquitoes break the skin barrier and probe the host tissue to find the blood. The saliva inoculated in this microenvironment modulates host hemostasis, inflammation and adaptive immune responses. However, the mechanisms involved in these biological activities remain poorly understood and few studies explored the potential roles of mosquito saliva on the individual cellular components of the immune system. Here, we report the immunomodulatory activities of Aedes aegypti salivary cocktail on murine peritoneal macrophages. RESULTS: The salivary gland extract (SGE) of Ae. aegypti inhibited the production of nitric oxide and inflammatory cytokines such as interleukin-6 (IL-6) and IL-12, as well as the expression of inducible nitric oxide synthase and NF-κB by murine macrophages stimulated by lipopolysaccharide (LPS) plus interferon-γ (IFN-γ). The spare respiratory capacity, the phagocytic and microbicidal activities of these macrophages were also reduced by Ae. aegypti SGE. These phenotypic changes are consistent with SGE suppressing the proinflammatory program of M1 macrophages. On the other hand, Ae. aegypti SGE did not influence M2-associated markers (urea production, arginase-1 and mannose receptor-1 expression), either in macrophages alternatively activated by IL-4 or in those classically activated by LPS plus IFN-γ. In addition, Ae. aegypti SGE did not display any cytokine-binding activity, nor did it affect macrophage viability, thus excluding supposed experimental artifacts. CONCLUSIONS: Given the importance of macrophages in a number of biological processes, our findings help to enlighten how vector saliva modulates vertebrate host immunity.
Assuntos
Aedes/imunologia , Diferenciação Celular , Inflamação , Macrófagos Peritoneais/imunologia , Saliva/imunologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Feminino , Fatores Imunológicos , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mosquitos Vetores/imunologia , Glândulas Salivares/química , Extratos de Tecidos/farmacologiaRESUMO
Receptors of the transient receptor potential (TRP) channels superfamily are expressed in many tissues and have different physiological functions. However, there are few studies investigating the role of these channels in cardiorespiratory control in mammals. We assessed the role of central and peripheral TRPV1 receptors in the cardiorespiratory responses to hypoxia (10% O2) and hypercapnia (7% CO2) by measuring pulmonary ventilation ( V Ë E ), heart rate (HR), mean arterial pressure (MAP) and body temperature (Tb) of male Wistar rats before and after intraperitoneal (AMG9810 [2.85 µg/kg, 1 mL/kg]) or intracebroventricular (AMG9810 [2.85 µg/kg, 1 µL] or AMG7905 [28.5 µg/kg, 1 µL]) injections of TRPV1 antagonists. Central or peripheral injection of TRPV1 antagonists did not change cardiorespiratory parameters or Tb during room air and hypercapnic conditions. However, the hypoxic ventilatory response was exaggerated by both central and peripheral injection of AMG9810. In addition, the peripheral antagonist blunted the drop in Tb induced by hypoxia. Therefore, the current data provide evidence that TRPV1 channels exert an inhibitory modulation on the hypoxic drive to breathe and stimulate the Tb reduction during hypoxia.
RESUMO
Considering that breast cancer usually begins in the lining of the ducts, local drug administration into the ducts could target cancers and pre-tumor lesions locally while reducing systemic adverse effects. In this study, a cationic bioadhesive nanoemulsion was developed for intraductal administration of C6 ceramide, a sphingolipid that mediates apoptotic and non-apoptotic cell death. Bioadhesive properties were obtained by surface modification with chitosan. The optimized nanoemulsion displayed size of 46.3 nm and positive charge, properties that were not affected by ceramide encapsulation (0.4%, w/w). C6 ceramide concentration necessary to reduce MCF-7 cells viability to 50% (EC50) decreased by 4.5-fold with its nanoencapsulation compared to its solution; a further decrease (2.6-fold) was observed when tributyrin (a pro-drug of butyric acid) was part of the oil phase of the nanocarrier, a phenomenon attributed to synergism. The unloaded nanocarrier was considered safe, as indicated by a score <0.1 in HET-CAM models, by the high survival rates of Galleria mellonella larvae exposed to concentrations ≤500 mg/mL, and absence of histological changes when intraductally administered in rats. Intraductal administration of the nanoemulsion prolonged drug localization for more than 120 h in the mammary tissue compared to its solution. These results support the advantage of the optimized nanoemulsion to enable mammary tissue localization of C6 ceramide.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Carcinoma Intraductal não Infiltrante/tratamento farmacológico , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/administração & dosagem , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Carcinoma Intraductal não Infiltrante/metabolismo , Carcinoma Intraductal não Infiltrante/patologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Galinhas , Emulsões , Feminino , Humanos , Células MCF-7 , Nanopartículas/metabolismo , Ratos , Resultado do TratamentoRESUMO
To elucidate the role of leptin in acute systemic inflammation, we investigated how its infusion at low, physiologically relevant doses affects the responses to bacterial lipopolysaccharide (LPS) in rats subjected to 24 h of food deprivation. Leptin was infused subcutaneously (0-20 µg·kg-1·h-1) or intracerebroventricularly (0-1 µg·kg-1·h-1). Using hypothermia and hypotension as biomarkers of systemic inflammation, we identified the phase extending from 90 to 240 min post-LPS as the most susceptible to modulation by leptin. In this phase, leptin suppressed the rise in plasma TNF-α and accelerated the recoveries from hypothermia and hypotension. Suppression of TNF-α was not accompanied by changes in other cytokines or prostaglandins. Leptin suppressed TNF-α when infused peripherally but not when infused into the brain. Importantly, the leptin dose that suppressed TNF-α corresponded to the lowest dose that limited food consumption; this dose elevated plasma leptin within the physiological range (to 5.9 ng/ml). We then conducted in vitro experiments to investigate whether an action of leptin on macrophages could parallel our in vivo observations. The results revealed that, when sensitized by food deprivation, LPS-stimulated peritoneal macrophages can be inhibited by leptin at concentrations that are lower than those reported to promote cytokine release. It is concluded that physiological levels of leptin do not exert a proinflammatory effect but rather an anti-inflammatory effect involving selective suppression of TNF-α via an action outside the brain. The mechanism of this effect might involve a previously unrecognized, suppressive action of leptin on macrophage subpopulations sensitized by food deprivation, but future studies are warranted.
Assuntos
Leptina/farmacologia , Macrófagos/efeitos dos fármacos , Animais , Citocinas/metabolismo , Febre/tratamento farmacológico , Privação de Alimentos/fisiologia , Inflamação/tratamento farmacológico , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Masculino , Ratos WistarRESUMO
This study introduces the respiratory exchange ratio (RER; the ratio of whole-body CO2 production to O2 consumption) as an aid to monitor metabolic acidosis during the early phase of endotoxic shock in unanesthetized, freely moving rats. Two serotypes of lipopolysaccharide (lipopolysaccharide [LPS] O55:B5 and O127:B8) were tested at shock-inducing doses (0.5-2 mg/kg). Phasic rises in RER were observed consistently across LPS serotypes and doses. The RER rise often exceeded the ceiling of the quotient for oxidative metabolism, and was mirrored by depletion of arterial bicarbonate and decreases in pH It occurred independently of ventilatory adjustments. These data indicate that the rise in RER results from a nonmetabolic CO2 load produced via an acid-induced equilibrium shift in the bicarbonate buffer. Having validated this new experimental aid, we asked whether acidosis was interconnected with the metabolic and thermal responses that accompany endotoxic shock in unanesthetized rats. Contrary to this hypothesis, however, acidosis persisted regardless of whether the ambient temperature favored or prevented downregulation of mitochondrial oxidation and regulated hypothermia. We then asked whether the substrate that fuels aerobic metabolism could be a relevant factor in LPS-induced acidosis. Food deprivation was employed to divert metabolism away from glucose oxidation and toward fatty acid oxidation. Interestingly, this intervention attenuated the RER response to LPS by 58%, without suppressing other key aspects of systemic inflammation. We conclude that acid production in unanesthetized rats with endotoxic shock results from a phasic activation of glycolysis, which occurs independently of physiological changes in mitochondrial oxidation and body temperature.
Assuntos
Acidose/metabolismo , Temperatura Corporal/fisiologia , Endotoxemia/metabolismo , Troca Gasosa Pulmonar/fisiologia , Acidose/induzido quimicamente , Acidose/fisiopatologia , Animais , Temperatura Corporal/efeitos dos fármacos , Metabolismo dos Carboidratos/efeitos dos fármacos , Dióxido de Carbono/metabolismo , Endotoxemia/complicações , Endotoxemia/fisiopatologia , Ácidos Graxos/metabolismo , Glucose/metabolismo , Lipopolissacarídeos/administração & dosagem , Lipopolissacarídeos/efeitos adversos , Lipopolissacarídeos/farmacologia , Masculino , Mitocôndrias/metabolismo , Mitocôndrias/fisiologia , Oxirredução/efeitos dos fármacos , Consumo de Oxigênio/fisiologia , Ratos , Ratos Wistar , Sorotipagem , Choque Séptico/complicações , Choque Séptico/metabolismo , Choque Séptico/fisiopatologiaRESUMO
Deep body temperature (Tb) is kept relatively constant despite a wide range of ambient temperature variation. Nevertheless, in particular situations it is beneficial to decrease or to increase Tb in a regulated manner. Under hypoxia for instance a regulated drop in Tb (anapyrexia) is key to reduce oxygen demand of tissues when oxygen availability is diminished, leading to an increased survival rate in a number of species when experiencing low levels of inspired oxygen. On the other hand, a regulated rise in Tb (fever) assists the healing process. These regulated changes in Tb are mediated by the brain, where afferent signals converge and the most important regions for the control of Tb are found. The brain (particularly some hypothalamic structures located in the preoptic area) modulates efferent activities that cause changes in heat production (modulating brown adipose tissue activity and perfusion, for instance) and heat loss (modulating tail skin vasculature blood flow, for instance). This review highlights key advances about the role of the gaseous neuromodulators nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) in thermoregulation, acting both on the brain and the periphery.