RESUMO
Obesity results from a chronic excessive accumulation of adipose tissue due to a long-term imbalance between energy intake and expenditure. Available epidemiological and clinical data strongly support the links between obesity and certain cancers. Emerging clinical and experimental findings have improved our understanding of the roles of key players in obesity-associated carcinogenesis such as age, sex (menopause), genetic and epigenetic factors, gut microbiota and metabolic factors, body shape trajectory over life, dietary habits, and general lifestyle. It is now widely accepted that the cancer-obesity relationship depends on the site of cancer, the systemic inflammatory status, and micro environmental parameters such as levels of inflammation and oxidative stress in transforming tissues. We hereby review recent advances in our understanding of cancer risk and prognosis in obesity with respect to these players. We highlight how the lack of their consideration contributed to the controversy over the link between obesity and cancer in early epidemiological studies. Finally, the lessons and challenges of interventions for weight loss and better cancer prognosis, and the mechanisms of weight gain in survivors are also discussed.
Assuntos
Neoplasias , Obesidade , Feminino , Humanos , Obesidade/complicações , Obesidade/metabolismo , Prognóstico , Neoplasias/epidemiologia , Neoplasias/etiologia , Carcinogênese , Fatores de RiscoRESUMO
Disruption of blood-brain barrier (BBB) function is a key feature of cerebral malaria. Increased barrier permeability occurs due to disassembly of tight and adherens junctions between endothelial cells, yet the mechanisms governing junction disassembly and vascular permeability during cerebral malaria remain poorly characterized. We found that EphA2 is a principal receptor tyrosine kinase mediating BBB breakdown during Plasmodium infection. Upregulated on brain microvascular endothelial cells in response to inflammatory cytokines, EphA2 is required for the loss of junction proteins on mouse and human brain microvascular endothelial cells. Furthermore, EphA2 is necessary for CD8+ T cell brain infiltration and subsequent BBB breakdown in a mouse model of cerebral malaria. Blocking EphA2 protects against BBB breakdown highlighting EphA2 as a potential therapeutic target for cerebral malaria.
Assuntos
Barreira Hematoencefálica/parasitologia , Malária Cerebral/parasitologia , Receptor EphA2/metabolismo , Adolescente , Animais , Barreira Hematoencefálica/metabolismo , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Malária Cerebral/genética , Malária Cerebral/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasmodium falciparum/fisiologia , Receptor EphA2/genéticaRESUMO
Prolonged oxygen therapy leads to oxidative stress, epithelial dysfunction, and acute lung injury in preterm infants and adults. Heterozygous Scnn1b mice, which overexpress lung epithelial sodium channels (ENaC), and their wild-type (WT) C57Bl6 littermates were utilized to study the pathogenesis of high fraction inspired oxygen ([Formula: see text])-induced lung injury. Exposure to high [Formula: see text] from birth to postnatal (PN) day 11 was used to model oxidative stress. Chronic exposure of newborn pups to 85% O2 increased glutathione disulfide (GSSG) and elevated the GSH/GSSG redox potential (Eh) of bronchoalveolar lavage fluid (BALF). Longitudinal X-ray imaging and Evans blue-labeled-albumin assays showed that chronic 85% O2 and acute GSSG (400 µM) exposures decreased alveolar fluid clearance (AFC) in the WT lung. Morphometric analysis of WT pups insufflated with GSSG (400 µM) or amiloride (1 µM) showed a reduction in alveologenesis and increased lung injury compared with age-matched control pups. The Scnn1b mouse lung phenotype was not further aggravated by chronic 85% O2 exposure. These outcomes support the hypothesis that exposure to hyperoxia increases GSSG, resulting in reduced lung fluid reabsorption due to inhibition of amiloride-sensitive ENaC. Flavin adenine dinucleotide (FADH2; 10 µM) was effective in recycling GSSG in vivo and promoted alveologenesis, but did not impact AFC nor attenuate fibrosis following high [Formula: see text] exposure. In conclusion, the data indicate that FADH2 may be pivotal for normal lung development, and show that ENaC is a key factor in promoting alveologenesis, sustaining AFC, and attenuating fibrotic lung injury caused by prolonged oxygen therapy in WT mice.
Assuntos
Lesão Pulmonar Aguda , Canais Epiteliais de Sódio , Oxigênio , Animais , Feminino , Masculino , Camundongos , Lesão Pulmonar Aguda/etiologia , Lesão Pulmonar Aguda/metabolismo , Lesão Pulmonar Aguda/patologia , Lesão Pulmonar Aguda/prevenção & controle , Amilorida/toxicidade , Bloqueadores do Canal de Sódio Epitelial/toxicidade , Canais Epiteliais de Sódio/genética , Canais Epiteliais de Sódio/metabolismo , Dissulfeto de Glutationa/toxicidade , Camundongos Endogâmicos C57BL , Oxigênio/toxicidadeRESUMO
Erythropoietin producing hepatocellular (Eph)-Eph receptor interacting (Ephrin) receptor-ligand signaling has been implicated in the development of tissue fibrosis, though it has not been well defined in the kidney. We detected substantial up-regulation of expression and phosphorylation of the EphB2 receptor tyrosine kinase in fibrotic kidney tissue obtained both from mice subjected to the unilateral renal ischemia-reperfusion (IR) model at 14 days and in patients suffering from chronic kidney disease (CKD). Knockout (KO) mice lacking EphB2 expression exhibited a normal renal structure and function, indicating no major role for this receptor in kidney development or action. Although IR injury is well-known to cause tissue damage, fibrosis, and renal dysfunction, we found that kidneys from EphB2KO mice showed much less renal tubular injury and retained a more preserved renal function. IR-injured kidneys from EphB2 KOs exhibited greatly reduced fibrosis and inflammation compared with injured wildtype (WT) littermates, and this correlated with a significant reduction in renal expression of profibrotic molecules, inflammatory cytokines, NADPH oxidases, and markers for cell proliferation, tubular epithelial-to-mesenchymal transition (EMT), myofibroblast activation, and apoptosis. A panel of 760 fibrosis-associated genes were further assessed, revealing that 506 genes in WT mouse kidney following IR injury changed their expression. However, 70.9% of those genes were back to or close to normal in expression when EphB2 was deleted. These data indicate that endogenous EphB2 expression and signaling are abnormally activated after kidney injury and subsequently contribute to the development of renal fibrosis via regulation of multiple profibrotic pathways.
Assuntos
Nefropatias/metabolismo , Rim/metabolismo , Receptor EphB2/metabolismo , Traumatismo por Reperfusão/metabolismo , Animais , Apoptose , Proliferação de Células , Modelos Animais de Doenças , Fibrose , Regulação da Expressão Gênica , Humanos , Mediadores da Inflamação/metabolismo , Rim/patologia , Nefropatias/genética , Nefropatias/patologia , Masculino , Camundongos Endogâmicos C57BL , Estresse Oxidativo , Receptor EphB2/genética , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/patologia , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/patologia , Transdução de SinaisRESUMO
BACKGROUND: Given the central importance of anti-malarial drugs in the treatment of malaria, there is a need to understand the effect of Plasmodium infection on the broad spectrum of drug metabolizing enzymes. Previous studies have shown reduced clearance of quinine, a treatment for Plasmodium infection, in individuals with malaria. METHODS: The hepatic expression of a large panel of drug metabolizing enzymes was studied in the livers of mice infected with the AS strain of Plasmodium chabaudi chabaudi, a nonlethal parasite in most strains of mice with several features that model human Plasmodium infections. C57BL/6J mice were infected with P. chabaudi by intraperitoneal injection of infected erythrocytes and sacrificed at different times after infection. Relative hepatic mRNA levels of various drug metabolizing enzymes, cytokines and acute phase proteins were measured by reverse transcriptase-real time PCR. Relative levels of cytochrome P450 proteins were measured by Western blotting with IR-dye labelled antibodies. Pharmacokinetics of 5 prototypic cytochrome P450 substrate drugs were measured by cassette dosing and high-resolution liquid chromatography-mass spectrometry. The results were analysed by MANOVA and post hoc univariate analysis of variance. RESULTS: The great majority of enzyme mRNAs were down-regulated, with the greatest effects occurring at the peak of parasitaemia 8 days post infection. Protein levels of cytochrome P450 enzymes in the Cyp 2b, 2c, 2d, 2e, 3a and 4a subfamilies were also down-regulated. Several distinct groups differing in their temporal patterns of regulation were identified. The cassette dosing study revealed that at the peak of parasitaemia, the clearances of caffeine, bupropion, tolbutamide and midazolam were markedly reduced by 60-70%. CONCLUSIONS: These findings in a model of uncomplicated human malaria suggest that changes in drug clearance in this condition may be of sufficient magnitude to cause significant alterations in exposure and response of anti-malarial drugs and co-medications.
Assuntos
Antimaláricos/farmacocinética , Sistema Enzimático do Citocromo P-450/metabolismo , Regulação para Baixo , Fígado/enzimologia , Malária/parasitologia , Plasmodium chabaudi/fisiologia , Proteínas de Fase Aguda/metabolismo , Animais , Citocinas/metabolismo , Eritrócitos/parasitologia , Feminino , Inativação Metabólica , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/metabolismoRESUMO
UNLABELLED: Beyond the well-defined role of the Eph (erythropoietin-producing hepatocellular) receptor tyrosine kinases in developmental processes, cell motility, cell trafficking/adhesion, and cancer, nothing is known about their involvement in liver pathologies. During blood-stage rodent malaria infection we have found that EphB2 transcripts and proteins were up-regulated in the liver, a result likely driven by elevated surface expression on immune cells including macrophages. This was significant for malaria pathogenesis because EphB2(-/-) mice were protected from malaria-induced liver fibrosis despite having a similar liver parasite burden compared with littermate control mice. This protection was correlated with a defect in the inflammatory potential of hepatocytes from EphB2(-/-) mice resulting in a reduction in adhesion molecules, chemokine/chemokine receptor RNA levels, and infiltration of leukocytes including macrophages/Kupffer cells, which mediate liver fibrosis during rodent malaria infections. These observations are recapitulated in the well-established carbon tetrachloride model of liver fibrosis in which EphB2(-/-) carbon tetrachloride-treated mice showed a significant reduction of liver fibrosis compared to carbon tetrachloride-treated littermate mice. Depletion of macrophages by clodronate-liposomes abrogates liver EphB2 messenger RNA and protein up-regulation and fibrosis in malaria-infected mice. CONCLUSION: During rodent malaria, EphB2 expression promotes malaria-associated liver fibrosis; to our knowledge, our data are the first to implicate the EphB family of receptor tyrosine kinases in liver fibrosis or in the pathogenesis of malaria infection.
Assuntos
Movimento Celular/imunologia , Hepatócitos/enzimologia , Cirrose Hepática/enzimologia , Cirrose Hepática/patologia , Receptor EphB2/metabolismo , Animais , Movimento Celular/fisiologia , Sobrevivência Celular , Células Cultivadas , Modelos Animais de Doenças , Progressão da Doença , Feminino , Hepatócitos/metabolismo , Células de Kupffer/metabolismo , Macrófagos/metabolismo , Malária/patologia , Malária/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Quimiocinas/metabolismo , Regulação para CimaRESUMO
OBJECTIVE: Erythropoietin-producing hepatocellular (Eph)/Ephrin cell-cell signaling is emerging as a key player in tissue fibrogenesis. The aim of this study was to test the hypothesis that the receptor tyrosine kinase EphB2 mediates dermal fibrosis in systemic sclerosis (SSc). METHODS: We assessed normal and SSc human skin biopsies for EphB2 expression. The in vivo role of EphB2 in skin fibrosis was investigated by subjecting EphB2-knockout mice to both bleomycin-induced and tight skin (Tsk1/+) genetic mouse models of skin fibrosis. EphB2 kinase-dead and overactive point mutant mice were used to evaluate the role of EphB2 forward signaling in bleomycin-induced dermal fibrosis. In vitro studies were performed on dermal fibroblasts from patients with SSc and healthy controls, which was followed by in vivo analysis of fibroblast-specific Ephb2-deficient mice. RESULTS: Expression of EphB2 is up-regulated in SSc skin tissue and explanted SSc dermal fibroblasts compared with healthy controls. EphB2 expression is elevated in two animal models of dermal fibrosis. In mice, EphB2 drives dermal fibrosis in both the bleomycin and the Tsk1/+ models of skin fibrosis. EphB2 forward signaling is a critical mediator of dermal fibrosis. Transforming growth factor-ß (TGF-ß) cytokines up-regulate EphB2 in dermal fibroblasts via noncanonical TGF-ß/mother against decapentaplegic signaling, and silencing EPHB2 in human dermal fibroblasts is sufficient to dampen TGF-ß-induced fibroblast-to-myofibroblast differentiation. Moreover, mice with fibroblast-specific deletion of EphB2 showed impaired fibroblast-to-myofibroblast differentiation and reduced skin fibrosis upon bleomycin challenge. CONCLUSION: Our data implicate TGF-ß regulation of EphB2 overexpression and kinase-mediated forward signaling in the development of dermal fibrosis in SSc. EphB2 thus represents a potential new therapeutic target for SSc.
Assuntos
Bleomicina , Fibroblastos , Fibrose , Camundongos Knockout , Receptor EphB2 , Escleroderma Sistêmico , Pele , Receptor EphB2/metabolismo , Receptor EphB2/genética , Escleroderma Sistêmico/metabolismo , Escleroderma Sistêmico/patologia , Escleroderma Sistêmico/genética , Animais , Humanos , Camundongos , Fibroblastos/metabolismo , Pele/patologia , Pele/metabolismo , Modelos Animais de Doenças , Transdução de Sinais/fisiologia , Regulação para Cima , Proteínas Serina-Treonina QuinasesRESUMO
Background: Hepatocellular carcinoma (HCC) incidence is increasing worldwide due to the obesity epidemic, which drives metabolic dysfunction-associated steatohepatitis (MASH) that can lead to HCC. However, the molecular pathways that lead to MASH-HCC are poorly understood. We have previously reported that male mice with global haploinsufficiency of hypoxia-associated factor, HAF ( SART1 +/ - ) spontaneously develop MASH/HCC. However, the cell type(s) responsible for HCC associated with HAF loss are unclear. Results: SART1 -floxed mice were crossed with mice expressing Cre-recombinase within hepatocytes (Alb-Cre; hepS -/- ) or macrophages (LysM-Cre, macS -/- ). Only hepS -/- mice (both male and female) developed HCC suggesting that HAF protects against HCC primarily within hepatocytes. HAF-deficient macrophages showed decreased P-p65 and P-p50 and in many major components of the NF-κB pathway, which was recapitulated using HAF siRNA in vitro . HAF depletion increased apoptosis both in vitro and in vivo , suggesting that HAF mediates a tumor suppressor role by suppressing hepatocyte apoptosis. We show that HAF regulates NF-κB activity by controlling transcription of TRADD and RIPK1 . Mice fed a high-fat diet (HFD) showed marked suppression of HAF, P-p65 and TRADD within their livers after 26 weeks, but manifest profound upregulation of HAF, P-65 and TRADD within their livers after 40 weeks of HFD, implicating deregulation of the HAF-NF-κB axis in the progression to MASH. In humans, HAF was significantly decreased in livers with simple steatosis but significantly increased in HCC compared to normal liver. Conclusions: HAF is novel transcriptional regulator of the NF-κB pathway that protects against hepatocyte apoptosis and is a key determinant of cell fate during progression to MASH and MASH-HCC.
RESUMO
OBJECTIVES: Curcumin is a natural plant product with antimalarial activity and immunomodulatory properties. In this study we aimed to investigate its effects on CD36 expression and CD36-mediated Plasmodium falciparum phagocytosis as well as the role played by reactive oxygen species (ROS) and the peroxisome proliferator-activated receptor γ retinoid X receptor (PPARγ-RXR) in these processes. METHODS: In vitro antimalarial activity was evaluated by the [³H]hypoxanthine assay. ROS production and surface CD36 in human monocyte/macrophages were measured by flow cytometry. PPARγ and CD36 mRNA expression was determined by the QuantiGene Plex® assay and RT-qPCR. Nuclear PPARγ activation was analysed by a DNA-binding ELISA while nuclear erythroid-related factor 2 (Nrf2) expression was analysed by western blotting. P. falciparum phagocytosis was assessed by light microscopy. RESULTS: Curcumin's antimalarial activity was confirmed and did not differ between drug-susceptible and -resistant P. falciparum strains. Curcumin increased monocyte ROS production and expression of PPARγ and CD36 at the mRNA and protein levels. Although PPARγ activation was blocked by the PPARγ antagonist GW9662, CD36 expression and CD36-mediated P. falciparum phagocytosis were only inhibited by N-acetylcysteine (NAC), suggesting a PPARγ-independent CD36 expression pathway. We then identified seven putative Nrf2 antioxidant response elements on the CD36 gene promoter and showed that NAC inhibited curcumin-induced Nrf2 protein expression. CONCLUSIONS: CD36 expression and CD36-mediated P. falciparum phagocytosis by curcumin are dependent on ROS production and probably involve the Nrf2 pathway. The dual immunomodulatory and antimalarial mechanisms of curcumin action may mean that curcumin has potential as an adjuvant treatment limiting the risk of recrudescence following standard antimalarial therapy.
Assuntos
Antígenos CD36/biossíntese , Curcumina/farmacologia , Fatores Imunológicos/farmacologia , Macrófagos/imunologia , Monócitos/imunologia , Fagocitose/efeitos dos fármacos , Plasmodium falciparum/imunologia , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Perfilação da Expressão Gênica , Humanos , Macrófagos/efeitos dos fármacos , Microscopia , Monócitos/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/biossíntese , PPAR gama/biossíntese , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Regulação para CimaRESUMO
Preterm infants and patients with lung disease often have excess fluid in the lungs and are frequently treated with oxygen, however long-term exposure to hyperoxia results in irreversible lung injury. Although the adverse effects of hyperoxia are mediated by reactive oxygen species, the full extent of the impact of hyperoxia on redox-dependent regulation in the lung is unclear. In this study, neonatal mice overexpressing the beta-subunit of the epithelial sodium channel (ß-ENaC) encoded by Scnn1b and their wild type (WT; C57Bl6) littermates were utilized to study the pathogenesis of high fraction inspired oxygen (FiO2)-induced lung injury. Results showed that O2-induced lung injury in transgenic Scnn1b mice is attenuated following chronic O2 exposure. To test the hypothesis that reversible cysteine-redox-modifications of proteins play an important role in O2-induced lung injury, we performed proteome-wide profiling of protein S-glutathionylation (SSG) in both WT and Scnn1b overexpressing mice maintained at 21% O2 (normoxia) or FiO2 85% (hyperoxia) from birth to 11-15 days postnatal. Over 7700 unique Cys sites with SSG modifications were identified and quantified, covering more than 3000 proteins in the lung. In both mouse models, hyperoxia resulted in a significant alteration of the SSG levels of Cys sites belonging to a diverse range of proteins. In addition, substantial SSG changes were observed in the Scnn1b overexpressing mice exposed to hyperoxia, suggesting that ENaC plays a critically important role in cellular regulation. Hyperoxia-induced SSG changes were further supported by the results observed for thiol total oxidation, the overall level of reversible oxidation on protein cysteine residues. Differential analyses reveal that Scnn1b overexpression may protect against hyperoxia-induced lung injury via modulation of specific processes such as cell adhesion, blood coagulation, and proteolysis. This study provides a landscape view of protein oxidation in the lung and highlights the importance of redox regulation in O2-induced lung injury.
Assuntos
Hiperóxia , Lesão Pulmonar , Humanos , Recém-Nascido , Animais , Camundongos , Hiperóxia/complicações , Hiperóxia/genética , Hiperóxia/metabolismo , Lesão Pulmonar/genética , Lesão Pulmonar/metabolismo , Cisteína/metabolismo , Recém-Nascido Prematuro , Pulmão/metabolismo , Oxirredução , Oxigênio , Proteínas/metabolismo , Camundongos Transgênicos , Animais Recém-NascidosRESUMO
The tumor microenvironment fuels tumorigenesis and induces the development of resistance to anticancer drugs. A growing number of reports support that the tumor microenvironment mediates these deleterious effects partly by overexpressing insulin-like growth factor 1 (IGF-1). IGF-1 is known for its role to support cancer progression and metastasis through the promotion of neovascularization in transforming tissues, and the promotion of the proliferation, maintenance and migration of malignant cells. Anti-IGF therapies showed potent anticancer effects and the ability to suppress cancer resistance to various chemotherapy drugs in in vivo and in vitro preclinical studies. However, high toxicity and resistance to these agents are increasingly being reported in clinical trials. We review data supporting the notion that tumor microenvironment mediates tumorigenesis partly through IGF-1 signaling pathway. We also discuss the therapeutic potential of IGF-1 receptor targeting, with special emphasis on the ability of IGF-R silencing to overcome chemotherapy drug resistance, as well as the challenges for clinical use of anti-IGF-1R therapies.
Assuntos
Fator de Crescimento Insulin-Like I , Neoplasias , Carcinogênese , Resistencia a Medicamentos Antineoplásicos , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Transdução de Sinais , Microambiente TumoralRESUMO
The clinical manifestations of cerebral malaria (CM) are well correlated with underlying major pathophysiological events occurring during an acute malaria infection, the most important of which, is the adherence of parasitized erythrocytes to endothelial cells ultimately leading to sequestration and obstruction of brain capillaries. The consequent reduction in blood flow, leads to cerebral hypoxia, localized inflammation and release of neurotoxic molecules and inflammatory cytokines by the endothelium. The pharmacological regulation of these immunopathological processes by immunomodulatory molecules may potentially benefit the management of this severe complication. Adjunctive therapy of CM patients with an appropriate immunomodulatory compound possessing even moderate anti-malarial activity with the capacity to down regulate excess production of proinflammatory cytokines and expression of adhesion molecules, could potentially reverse cytoadherence, improve survival and prevent neurological sequelae. Current major drug discovery programmes are mainly focused on novel parasite targets and mechanisms of action. However, the discovery of compounds targeting the host remains a largely unexplored but attractive area of drug discovery research for the treatment of CM. This review discusses the properties of the plant immune-modifier curcumin and its potential as an adjunctive therapy for the management of this complication.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Antimaláricos/uso terapêutico , Curcumina/uso terapêutico , Fatores Imunológicos/uso terapêutico , Malária Cerebral/tratamento farmacológico , Plantas/química , Suplementos Nutricionais , Quimioterapia Combinada , Humanos , Malária/tratamento farmacológico , Malária/imunologia , Malária Cerebral/imunologiaRESUMO
BACKGROUND: The efficacy of amodiaquine (AQ), sulphadoxine-pyrimethamine (SP) and the combination of SP+AQ in the treatment of Cameroonian children with clinical malaria was investigated. The prevalence of molecular markers for resistance to these drugs was studied to set the baseline for surveillance of their evolution with time. METHODS: Seven hundred and sixty children aged 6-59 months with uncomplicated falciparum malaria were studied in three ecologically different regions of Cameroon - Mutengene (littoral equatorial forest), Yaoundé (forest-savannah mosaic) and Garoua (guinea-savannah). Study children were randomized to receive either AQ, SP or the combination AQ+SP. Clinical outcome was classified according to WHO criteria, as either early treatment failure (ETF), late clinical failure (LCF), late parasitological failure (LPF) or adequate clinical and parasitological response (ACPR). The occurrence of mutations in pfcrt, pfmdr1, dhfr and dhps genes was studied by either RFLP or dot blot techniques and the prevalence of these mutations related to parasitological and therapeutic failures. RESULTS: After correction for the occurrence of re-infection by PCR, ACPRs on day 28 for AQ, SP and AQ+SP were 71.2%, 70.1% and 80.9%, in Garoua, 79.2%, 62.5%, and 81.9% in Mutengene, and 80.3%, 67.5% and 76.2% in Yaoundé respectively. High levels of Pfcrt 76T (87.11%) and Pfmdr1 86Y mutations (73.83%) were associated with quinoline resistance in the south compared to the north, 31.67% (76T) and 22.08% (86Y). There was a significant variation (p < 0.001) of the prevalence of the SGK haplotype between Garoua in the north (8.33%), Yaoundé (36.29%) in the savannah-forest mosaic and Mutengene (66.41%) in the South of Cameroon and a weak relation between SGK haplotype and SP failure. The 540E mutation on the dhps gene was extremely rare (0.3%) and occurred only in Mutengene while the pfmdr1 1034K and 1040D mutations were not detected in any of the three sites. CONCLUSION: In this study the prevalence of molecular markers for quinoline and anti-folate resistances showed high levels and differed between the south and north of Cameroon. AQ, SP and AQ+SP treatments were well tolerated but with low levels of efficacy that suggested alternative treatments were needed in Cameroon since 2005.
Assuntos
Amodiaquina/uso terapêutico , Antimaláricos/uso terapêutico , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Pirimetamina/uso terapêutico , Sulfadoxina/uso terapêutico , Administração Oral , Camarões/epidemiologia , Pré-Escolar , Método Duplo-Cego , Esquema de Medicação , Combinação de Medicamentos , Monitoramento de Medicamentos , Resistência a Medicamentos , Quimioterapia Combinada , Feminino , Seguimentos , Política de Saúde , Humanos , Lactente , Malária Falciparum/epidemiologia , Masculino , Testes de Sensibilidade Parasitária , Plasmodium falciparum/isolamento & purificação , Fatores de Tempo , Resultado do TratamentoRESUMO
Hepatic fibrosis is the result of an excessive wound-healing response subsequent to chronic liver injury. A feature of liver fibrogenesis is the secretion and deposition of extracellular matrix proteins by activated hepatic stellate cells (HSCs). Here we report that upregulation of EphB2 is a prominent feature of two mouse models of hepatic fibrosis and also observed in humans with liver cirrhosis. EphB2 is upregulated and activated in mouse HSCs following chronic carbon tetrachloride (CCl4) exposure. Moreover, we show that EphB2 deficiency attenuates liver fibrosis and inflammation and this is correlated with an overall reduction in pro-fibrotic markers, inflammatory chemokines and cytokines. In an in vitro system of HSCs activation we observed an impaired proliferation and sub-optimal differentiation into fibrogenic myofibroblasts of HSCs isolated from EphB2-/- mice compared to HSCs isolated from wild type mice. This supports the hypothesis that EphB2 promotes liver fibrosis partly via activation of HSCs. Cellular apoptosis which is generally observed during the regression of liver fibrogenesis was increased in liver specimens of CCl4-treated EphB2-/- mice compared to littermate controls. This data is suggestive of an active repair/regeneration system in the absence of EphB2. Altogether, our data validate this novel pro-fibrotic function of EphB2 receptor tyrosine kinase.
Assuntos
Células Estreladas do Fígado/patologia , Cirrose Hepática/genética , Cirrose Hepática/patologia , Miofibroblastos/patologia , Receptor EphB2/genética , Animais , Tetracloreto de Carbono/farmacologia , Células Cultivadas , Modelos Animais de Doenças , Feminino , Células Estreladas do Fígado/metabolismo , Humanos , Cirrose Hepática Experimental/induzido quimicamente , Cirrose Hepática Experimental/genética , Cirrose Hepática Experimental/patologia , Camundongos , Camundongos Endogâmicos C57BL , Miofibroblastos/metabolismoRESUMO
Alterations in the mechanical properties of erythrocytes occurring in inflammatory and hematologic disorders such as sickle cell disease (SCD) and malaria often lead to increased endothelial permeability, haemolysis, and microvascular obstruction. However, the associations among these pathological phenomena remain unknown. Here, we report a perfusable, endothelialized microvasculature-on-a-chip featuring an interpenetrating-polymer-network hydrogel that recapitulates the stiffness of blood-vessel intima, basement membrane self-deposition and self-healing endothelial barrier function for longer than 1 month. The microsystem enables the real-time visualization, with high spatiotemporal resolution, of microvascular obstruction and endothelial permeability under physiological flow conditions. We found how extracellular heme, a hemolytic byproduct, induces delayed but reversible endothelial permeability in a dose-dependent manner, and demonstrate that endothelial interactions with SCD or malaria-infected erythrocytes cause reversible microchannel occlusion and increased in situ endothelial permeability. The microvasculature-on-a-chip enables mechanistic insight into the endothelial barrier dysfunction associated with SCD, malaria and other inflammatory and haematological diseases.
Assuntos
Plaquetas , Malária , Animais , Grânulos Citoplasmáticos , Modelos Animais de Doenças , CamundongosRESUMO
The Eph receptor tyrosine kinases interact with their ephrin ligands on adjacent cells to facilitate contact-dependent cell communication. Ephrin B ligands are expressed on T cells and have been suggested to act as co-stimulatory molecules during T cell activation. There are no detailed reports of the expression and modulation of EphB receptors on dendritic cells, the main antigen presenting cells that interact with T cells. Here we show that mouse splenic dendritic cells (DC) and bone-marrow derived DCs (BMDC) express EphB2, a member of the EphB family. EphB2 expression is modulated by ligation of TLR4 and TLR9 and also by interaction with ephrin B ligands. Co-localization of EphB2 with MHC-II is also consistent with a potential role in T cell activation. However, BMDCs derived from EphB2 deficient mice were able to present antigen in the context of MHC-II and produce T cell activating cytokines to the same extent as intact DCs. Collectively our data suggest that EphB2 may contribute to DC responses, but that EphB2 is not required for T cell activation. This result may have arisen because DCs express other members of the EphB receptor family, EphB3, EphB4 and EphB6, all of which can interact with ephrin B ligands, or because EphB2 may be playing a role in another aspect of DC biology such as migration.