Hundreds of antimicrobial peptides create a selective barrier for insect gut symbionts.

The spatial organization of gut microbiota is crucial for the functioning of the gut ecosystem, although the mechanisms that organize gut bacterial communities in microhabitats are only partially understood. The gut of the insect Riptortus pedestris has a characteristic microbiota biogeography with a multispecies community in the anterior midgut and a monospecific bacterial population in the posterior midgut. We show that the posterior midgut region produces massively hundreds of specific antimicrobial peptides (AMPs), the Crypt-specific Cysteine-Rich peptides (CCRs) that have membrane-damaging antimicrobial activity against diverse bacteria but posterior midgut symbionts have elevated resistance. We determined by transposon-sequencing the genetic repertoire in the symbiont Caballeronia insecticola to manage CCR stress, identifying different independent pathways, including AMP-resistance pathways unrelated to known membrane homeostasis functions as well as cell envelope functions. Mutants in the corresponding genes have reduced capacity to colonize the posterior midgut, demonstrating that CCRs create a selective barrier and resistance is crucial in gut symbionts. Moreover, once established in the gut, the bacteria differentiate into a CCR-sensitive state, suggesting a second function of the CCR peptide arsenal in protecting the gut epithelia or mediating metabolic exchanges between the host and the gut symbionts. Our study highlights the evolution of an extreme diverse AMP family that likely contributes to establish and control the gut microbiota.

Exploring the use of ChatGPT in predicting anterior circulation stroke functional outcomes after mechanical thrombectomy: a pilot study.

BACKGROUND: Accurate prediction of functional outcomes is crucial in stroke management, but this remains challenging. OBJECTIVE: To evaluate the performance of the generative language model ChatGPT in predicting the functional outcome of patients with acute ischemic stroke (AIS) 3 months after mechanical thrombectomy (MT) in order to assess whether ChatGPT can used to be accurately predict the modified Rankin Scale (mRS) score at 3 months post-thrombectomy. METHODS: We conducted a retrospective analysis of clinical, neuroimaging, and procedure-related data from 163 patients with AIS undergoing MT. The agreement between ChatGPT's exact and dichotomized predictions and actual mRS scores was assessed using Cohen's κ. The added value of ChatGPT was measured by evaluating the agreement of predicted dichotomized outcomes using an existing validated score, the MT-DRAGON. RESULTS: ChatGPT demonstrated fair (κ=0.354, 95% CI 0.260 to 0.448) and good (κ=0.727, 95% CI 0.620 to 0.833) agreement with the true exact and dichotomized mRS scores at 3 months, respectively, outperforming MT-DRAGON in overall and subgroup predictions. ChatGPT agreement was higher for patients with shorter last-time-seen-well-to-door delay, distal occlusions, and better modified Thrombolysis in Cerebral Infarction scores. CONCLUSIONS: ChatGPT adequately predicted short-term functional outcomes in post-thrombectomy patients with AIS and was better than the existing risk score. Integrating AI models into clinical practice holds promise for patient care, yet refining these models is crucial for enhanced accuracy in stroke management.

Fish fauna of the São Francisco River Interbasin Water Transfer reservoirs / Ictiofauna dos reservatórios do Projeto de Integração do Rio São Francisco

Abstract Artificial impoundments are frequently built to mitigate the water scarcity in the drylands such as the Caatinga region in Brazil. The São Francisco Interbasin Water Transfer (SF-IWT) megaproject implemented many artificial reservoirs for that purpose. A checklist of fish species from the SF-IWT reservoirs is provided based on samples from eight years of monitoring. The collections were conducted semiannually at 28 reservoirs divided into three groups: the East Axis, North Axis, and Agreste Branch. The SF-IWT reservoirs presented a total of 47 species, 46 were recorded in the North Axis, 27 in the East Axis, and only seven in the Agreste Branch. Characids and cichlids represented most of the species. The three analyzed groups of reservoirs presented distinct communities and the reservoirs' age, richness and abundance were relevant variables responsible for fish composition. The SF-IWT reservoirs present a diverse and heterogeneous ichthyofauna, typical of lentic environments. The main colonizers of the SF-IWT reservoirs were fish from the São Francisco donor basin, invasive species anthropically released in those sites, and eventual species from the surrounding receiving basins. As the accumulation curves suggested, a continuous effort could reveal additional species, patterns in long-term colonization, and contribute to data on the reservoirs' future stabilization phase. Since invasive species were present in most reservoirs, along with donor-basin native species with potential to disperse to the receiving basins, a continuous and detailed monitoring is key for management planning and possible impacts assessment.

Resumo Barramentos artificiais são comumente construídos para mitigar a escassez hídrica em áreas semiáridas como a região da Caatinga brasileira. O Projeto de Integração do Rio São Francisco (PISF) com Bacias Hidrográficas do Nordeste Setentrional implementou muitos reservatórios artificiais com este propósito. Uma lista de espécies de peixes dos reservatórios do PISF foi obtida após amostragens realizadas em oito anos de monitoramento. As campanhas foram realizadas semestralmente em 28 reservatórios divididos em três grupos: Eixo Leste, Eixo Norte e Ramal do Agreste. Os reservatórios amostrados apresentaram um total de 47 espécies, 46 delas foram registradas no Eixo Norte, 27 no Eixo Leste e apenas sete no Ramal do Agreste. Characidae e Cichlidae foram as famílias mais representativas. Os três grupos de reservatórios analisados apresentaram comunidades distintas e a idade, a riqueza e a abundância de cada reservatório foram as variáveis que mais influenciaram a composição das espécies de peixes. Os reservatórios do PISF apresentaram uma ictiofauna diversa e heterogênea, característica de ambientes lênticos. Os principais colonizadores dos reservatórios do PISF foram peixes da bacia doadora do São Francisco, espécies invasoras antropicamente liberadas nesses locais e eventuais espécies das bacias receptoras do entorno. De acordo com o resultado das curvas de acúmulo, um esforço contínuo poderia revelar espécies adicionais, padrões na colonização em longo prazo e contribuir com dados para a fase futura de estabilização dos reservatórios. Visto que espécies invasoras estiveram presentes em quase todos os reservatórios, juntamente com espécies nativas da bacia doadora com potencial de dispersão para as bacias receptoras, um monitoramento continuo e detalhado é essencial para o planejamento de manejo e avaliação de impactos.

Experimentações estéticas: o cuidado de si, do outro e do ambiente em que vivemos / Apropiaciones sociopoéticas: experimentaciones estéticas del cuidado sociopoetics / Aesthetic trials: taking care of oneself, of the other and of the environment in which we live

Objective: To present intervention research developed by the authors in the form of artistic and educational activities, called aesthetic experiments, analyzing them and their effects as a practical-theoretical set directed themselves, each other and the environment. Methods: It was built from the authors’ experience with research practices inspired by studies of The Three Ecologies and socialpoetics methodology, being used in the analysis face-to-face writing of the participants during the workshop and the answers to the questions sent by e-mail. Results: They point to the overcoming of inner fears and the discovery of personal potential to face challenges. The sensibility of the gaze and the involvement with the other as a fundamental element in the exercise of confidence in daily relationships. Conclusion: The experimentation process indicates that there is a power of the meeting, the exchange and sensibility when we privilege knowledge that is learned with the body in motion, relating to the other and the world.

Objetivo: apresentar a pesquisa-intervenção desenvolvida pelos autores em forma de atividades artísticopedagógicas, denominadas experimentações estéticas, analisando-as e seus efeitos enquanto conjunto práticoteórico voltado ao cuidado de si, do outro e do ambiente. Métodos: Construído a partir da experiência dos autores com práticas de pesquisa inspiradas nos estudos sobre as três ecologias e na metodologia sociopoética, sendo utilizada na análise a escrita presencial dos participantes durante as oficinas e as respostas deles às questões enviadas por e-mail. Resultados: Apontam para a superação dos medos internos e a descoberta das potencialidades pessoais para enfrentar desafios. A sensibilidade do olhar e o envolvimento com o outro como elemento fundamental no exercício de confiança das relações cotidianas. Conclusão: O processo de experimentação indica que existe uma potência do encontro, dos intercâmbios e da sensibilidade quando privilegiamos um conhecimento que se apreende com o corpo em movimento, relacionando-se com o outro e o mundo.

Objetivo: presentar la investigación-intervención desarrollada por los autores en forma de actividades artísticas y educativas, llamadas experimentos estéticos, analizandolos y a sus efectos enquanto um conjunto práctico-teórico dirigido al cuidado de sí, de los demás y de El medio ambiente. Métodos: Construido a partir de la experiencia de lós autores con las prácticas de investigación inspirados en los estudios sobre los tres ecologías y en metodología Sociopoética, siendo utilizados em el análisis los registros por escrito de los participantes durante el taller y las respuestas a las preguntas enviadas por e-mail. Resultados: indica la superación de los miedos internos y el descubrimiento del potencial personal para enfrentar los desafíos. La sensibilidad del ojo y la implicación con el otro como un elemento fundamental en el ejercicio de la confianza de las relaciones cotidianas. Conclusión: El proceso de experimentación indica que hay una potencia de lo encuentro, de lo intercambio y de La sensibilidad cuándo es privilegiado un conocimiento que se aprende com el cuerpo en movimiento, en relación con los demás y el mundo.

Structure activity characterization of Bordetella petrii lipid A, from environment to human isolates.

Bordetella petrii, a facultative anaerobic species, is the only known member of the Bordetella genus with environmental origin. However it was also recently isolated from humans. The structures of the B. petrii lipid A moieties of the endotoxins were characterized here for the first time for an environmental strain and compared to that of human isolates. Characterization was achieved using chemical analyses, gas chromatography-mass spectrometry, and Matrix Assisted Laser Desorption Ionisation mass spectrometry. The analyses revealed that the different lipid A structures contain a common bisphosphorylated ß-(1→6)-linked d-glucosamine disaccharide with hydroxytetradecanoic acid in amide as well at the C-3' in ester linkages. Similar to Bordetella pertussis and Bordetella bronchiseptica lipids A, the hydroxytetradecanoic acid at the C-2' position was substituted by tetradecanoic acid. Unlike B. pertussis, the hydroxytetradecanoic acid at the C-2 position was substituted with either 12:0 or 14:0 and/or their 2-OH forms. Depending on the environmental or human origin the structures differed in the length and degree of fatty acid acylation and impacted the IL-6 and TNF-α inflammatory responses tested. In one isolate we showed the presence at the C-3 position of the short-chain 10:0(3-OH), which according to our previous analyses is more characteristic of the human pathogens in the genus like B. pertussis and Bordetella parapertussis.

Clinical and Radiological Characterization of Progressive Multifocal Leukoencephalopathy in HIV-Infected Patients: A Retrospective Analysis and Review of the Literature.

INTRODUCTION: Progressive multifocal leukoencephalopathy is a demyelinating disease of the central nervous system caused by John Cunningham virus, mostly associated with immunodeficiency conditions, such as the human immunodeficiency virus infection. Progressive multifocal leukoencephalopathy can have multiple clinical features and usually presents a typical lesion pattern on brain magnetic resonance imaging. Its course may be rapidly progressive, although immunological responsiveness can be associated with an improved prognosis. MATERIAL AND METHODS: We performed a retrospective analysis of the clinical and radiological data from patients admitted in our institution between January 2005 and April 2014 with the diagnosis of definitive progressive multifocal leukoencephalopathy (ICD10:A81.2) in the setting of human immunodeficiency virus infection. RESULTS: Twenty-one patients were included in our study, mostly men (n = 20, 95.2%). Mean age at diagnosis was 39 years. Motor deficits were the most common clinical finding. John Cunningham virus-DNA was detected in the cerebral spinal fluid in 20 patients (95.2%). Brain imaging studies most commonly disclosed bilateral supratentorial, asymmetric lesions. Four (19%) patients developed immune reconstitution inflammatory syndrome in the follow-up. Therapeutic approach included initiation and continuation/optimization of antiretroviral therapy, with adjunctive therapy with corticosteroids in four patients. Seventeen (81%) patients died during the study period; median survival time following progressive multifocal leukoencephalopathy diagnosis was 3 months (range 1 - 13). DISCUSSION: The results of our study are in accordance with the data previously published on progressive multifocal leukoencephalopathy in human immunodeficiency virus patients. Progressive multifocal leukoencephalopathy is predominantly associated with severe immunosuppression, particularly in patients who are not under anti-retroviral therapy, and usually presents with motor and cognitive symptoms and signs. A typical bilateral asymmetric pattern in conventional magnetic resonance imaging is present in the majority of the patients. There is no specific therapy for progressive multifocal leukoencephalopathy and it is usually fatal, although outcomes can improve with highly active anti-retroviral therapy. Immune reconstitution inflammatory syndrome is also an important complication related with progressive multifocal leukoencephalopathy, usually associated with anti-retroviral therapy. Progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome presents with different imaging characteristics from progressive multifocal leukoencephalopathy and treatment with steroids can improve survival. CONCLUSION: The mortality rate and long-term neurological morbidity associated with progressive multifocal leukoencephalopathy are quite high. These data should increase clinician awareness to the occurrence of progressive multifocal leukoencephalopathy among human immunodeficiency virus patients and highlight the important role of magnetic resonance imaging, as early diagnosis may beassociated with better outcome.

Introdução: A leucoencefalopatia multifocal progressiva é uma patologia desmielinizante causada pelo vírus John Cunningham, geralmente associada a estados de imunodepressão, em particular a infeção pelo vírus da imunodeficiência humana. Pode apresentar múltiplas manifestações clínicas e tem habitualmente um padrão imagiológico típico. A evolução clínica é geralmente progressiva, podendo ocorrer uma melhoria do prognóstico associada à recuperação imunológica.Material e Métodos: Foi conduzida uma análise retrospetiva dos dados clínicos e imagiológicos de doentes admitidos no nosso Hospital entre janeiro de 2005 e abril de 2014 com o diagnóstico de leucoencefalopatia multifocal progressiva (ICD10:A81.2) associado a infeção por vírus da imunodeficiência humana.Resultados: Vinte e um doentes foram incluídos, sendo 20 do sexo masculino (95,2%). A idade média na altura do diagnóstico foi 39 anos. A forma de apresentação mais frequente foi défice motor. O vírus John Cunningham foi identificado no líquido cefalorraquidiano em 20 doentes (95,2%). Nos estudos de imagem verificou-se um predomínio de lesões supratentoriais, assimétricas e bilaterais. Quatro doentes (19%) desenvolveram síndrome inflamatória de resposta imunológica. A abordagem terapêutica incluiu início ou otimização de terapêutica anti-retrovirica, associada a corticoterapia em quatro casos. Dezassete (81%) doentes morreram no período do estudo, sendo a sobrevida mediana após diagnóstico de três meses (intervalo 1 a13).Discussão: Os resultados do nosso estudo são concordantes com os dados previamente publicados relativamente à leucoencefalopatia multifocal progressiva, evidenciando a sua associação à infecção pelo vírus da imunodeficiência humana, particularmente nos doentes com imunossupressão grave, o predomínio de sinais e sintomas motores e cognitivos, e a existência de um atingimento bilateral e assimétrico evidente nas sequências convencionais dos estudos de ressonância magnética. Não existe terapêutica específica e esta patologia é normalmente fatal, apesar de se verificar um aumento da sobrevida associado à terapêutica anti-retrovírica. A síndrome inflamatória de reconstituição imunológica é uma complicação associada a leucoencefalopatia multifocal progressiva, habitualmente ocorrendo após início de terapêutica anti-retrovírica, apresentando caraterísticas imagiológicas diferentes da leucoencefalopatia multifocal progressiva. A instituição de corticoterapia pode melhorar o prognóstico dos doentes que desenvolvem síndrome inflamatória de reconstituição imunológica associada a leucoencefalopatia multifocal progressiva.Conclusão: A mortalidade e morbilidade associadas à leucoencefalopatia multifocal progressiva são elevadas, com sequelas neurológicas importantes a longo-prazo. Os dados apresentados deverão alertar os clínicos para a ocorrência desta patologia nos doentes com infecção vírus da imunodeficiência humana, evidenciando o papel cada vez mais determinante da Ressonância Magnética no diagnóstico precoce da leucoencefalopatia multifocal progressiva e consequente melhoria do prognóstico.

Pituitary incidentalomas: analysis of a neuroradiological cohort.

PURPOSE: Most pituitary lesions are detected during the investigation of symptoms associated with hormonal dysfunction and vision abnormalities. When the lesion is identified in an image performed for reasons not related to the tumor, the term incidentaloma applies. Our aim was to describe the diagnosis behind pituitary incidentalomas, patient characteristics and their follow up. METHODS: We searched for the terms "pituitary", "hypophysis" and "incidentaloma" in the requisitions and reports of all CTs and MRIs performed between 1st September 2008 and 30th October 2013. We retrieved demographic data as well as information regarding presentation and follow-up. RESULTS: We detected 71 pituitary incidentalomas, 3 in children/adolescents. In adult patients, mean age was 51.6 ± 18.46 years and 42 were female (61.8 %). The most frequent reason for imaging was headache (33.8 %). The image that first detected the incidentaloma was CT scan in 63.2 and 17.6 % patients presented symptoms that could have led to earlier diagnosis. Pituitary adenoma is the most prevalent lesion (n 48; 70.6 %), followed by Rathke's cleft cyst (n 9; 13.2 %). Hormonal evaluation revealed hypopituitarism in 14 patients and hypersecretion in 6: 5 prolactinomas and 1 somatotroph adenoma. Twenty-one (28.8 %) patients underwent surgery and there was no malignancy. CONCLUSIONS: In concordance with available literature, adenomas are the most frequent incidentally found pituitary lesions. Hormonal dysfunction is quite prevalent, including symptomatic presentations, which suggests that there seems to be a low sensitivity for the diagnosis of pituitary disease.

Naringin accelerates the regression of pre-neoplastic lesions and the colorectal structural reorganization in a murine model of chemical carcinogenesis.

The aim of this study was to investigate the effect of Naringin on pre-neoplastic colorectal lesions induced by chemical carcinogen in rats. Female Wistar rats weighing 130.8±27.1 g received weekly one subcutaneous injection of 1,2-dimethylhydrazine (DMH, 20 mg/kg) for 10 weeks. The animals were divided into 5 groups with 6 animals in each group. Group 1: 0.9% saline; Group 2: DMH+0.9% saline; Group 3: DMH+Naringin (10 mg/kg); Group 4: DMH+Naringin (100 mg/kg); Group 5: DMH+Naringin (200 mg/kg). G2 and G3 showed a significant increase in ACF number, AgNOR/nucleus and mitosis compared to G1. G4 and G5 presented a significant reduction in these parameters compared to G2. The number of cells producing acidic and neutral mucins, red blood cells and the level of antioxidant minerals, such as copper, magnesium, selenium and zinc, were significantly reduced in G2 and G3, but similar in G4 and G5 compared to G1. Naringin, especially at 200 mg/kg, was effective in reducing the number of pre-neoplastic lesions in rats exposed to DMH. Some of these effects may be due to reduction in cellular proliferation and tissue levels of iron together with the recovery of antioxidant mineral levels induced by this flavonoid.

Diferenciação de células-tronco mesenquimais derivadas do tecido adiposo em cardiomiócitos / Differentiation of adipose tissue-derived mesenchymal stem cells into cardiomyocytes

FUNDAMENTO: O potencial de renovação e proliferação dos cardiomiócitos, in vivo, é pequeno, e por isso, o músculo cardíaco apresenta limitada capacidade de repor células perdidas. Na tentativa de minimizar os danos oriundos de lesões hipóxico-isquêmicas e daquelas que acometem o sistema de condução do coração, a terapia celular com células-tronco mesenquimais (MSC) vem sendo utilizada, inclusive com cardiomiócitos diferenciados a partir de MSC. OBJETIVO: O presente trabalho comparou três protocolos distintos de indução de diferenciação objetivando a sugestão de um método viável para a diferenciação de maior número de células funcionais que expressem fenótipo cardiomiogênico. MÉTODOS: Culturas de MSC obtidas de tecido adiposo de ratos jovens da linhagem Lewis transgênicos para proteína verde fluorescente (GFP) foram submetidos a três diferentes meios de diferenciação cardiogênica: Planat-Bérnard, 5-azacitidina e meio Planat-Bérnard + 5-azacitidina e observadas quanto a expressão de marcadores celulares cardíacos. RESULTADOS: Nos três protolocos utilizados observou-se formação da proteína alfa-actinina sarcomérica no citoesqueleto das células submetidas à diferenciação, expressão de conexina 43 na membrana nuclear e citoplasmática e formação de gap junctions, necessárias para a propagação do impulso elétrico no miocárdio, contudo, em nenhum protocolo foi observada contração espontânea das células submetidas à diferenciação cardiogênica. CONCLUSÃO: A indução com 5-azacitidina proporcionou diferenciação celular cadiomiogênica efetiva e similar à encontrada com o meio Planat-Bénard e, por ser um protocolo mais simples, rápido e com menor custo torna-se o método de eleição.

BACKGROUND: Cardiomyocytes have small potential for renovation and proliferation in vivo. Consequently, the heart muscle has limited capacity of self-renewal. Mesenchymal stem cells (MSC) therapy, as well as MSC differentiated into cardiomyocytes, has been used in the attempt to minimize the effects of ischemic-hypoxic lesions and those affecting the electrical conduction system of the heart. OBJECTIVE: The present study compared three distinct protocols for induced differentiation of MSC into cardiomyocytes aimed at finding a viable method for producing a large number of functional cells expressing cardiomyogenic phenotype. METHODS: Mesenchymal stem cells were obtained from the adipose tissue of young transgenic Lewis rats expressing green fluorescent protein (GFP), and submitted to three distinct differentiation-inducing media: 1) Planat-Bérnard, 2) 5-azacytidine, and 3) Planat-Bérnard + 5-azacytidine; further, these cells were identified based on the expression of cardiac cell markers. RESULTS: All three protocols detected the expression of sarcomeric-alpha-actinin protein in the exoskeleton of cells, expression of connexin-43 in the nuclear and cytoplasmic membrane, and formation of gap junctions, which are necessary for electrical impulse propagation in the myocardium. However, no spontaneous cell contraction was observed with any of the tested protocols. CONCLUSION: Induction with 5-azacytidine provided an effective cadiomyogenic cellular differentiation similar to that obtained with Planat-Bénard media. Therefore, 5-azacytidine was the method of choice for being the simplest, fastest and lowest-cost protocol for cell differentiation.

Differentiation of adipose tissue-derived mesenchymal stem cells into cardiomyocytes.

BACKGROUND: Cardiomyocytes have small potential for renovation and proliferation in vivo. Consequently, the heart muscle has limited capacity of self-renewal. Mesenchymal stem cells (MSC) therapy, as well as MSC differentiated into cardiomyocytes, has been used in the attempt to minimize the effects of ischemic-hypoxic lesions and those affecting the electrical conduction system of the heart. OBJECTIVE: The present study compared three distinct protocols for induced differentiation of MSC into cardiomyocytes aimed at finding a viable method for producing a large number of functional cells expressing cardiomyogenic phenotype. METHODS: Mesenchymal stem cells were obtained from the adipose tissue of young transgenic Lewis rats expressing green fluorescent protein (GFP), and submitted to three distinct differentiation-inducing media: 1) Planat-Bérnard, 2) 5-azacytidine, and 3) Planat-Bérnard + 5-azacytidine; further, these cells were identified based on the expression of cardiac cell markers. RESULTS: All three protocols detected the expression of sarcomeric-alpha-actinin protein in the exoskeleton of cells, expression of connexin-43 in the nuclear and cytoplasmic membrane, and formation of gap junctions, which are necessary for electrical impulse propagation in the myocardium. However, no spontaneous cell contraction was observed with any of the tested protocols. CONCLUSION: Induction with 5-azacytidine provided an effective cadiomyogenic cellular differentiation similar to that obtained with Planat-Bénard media. Therefore, 5-azacytidine was the method of choice for being the simplest, fastest and lowest-cost protocol for cell differentiation.

Aterosclerose experimental em coelhos / Experimental atherosclerosis in rabbits

Numerosas pesquisas têm sido realizadas utilizando modelos experimentais para estudar o desenvolvimento da aterosclerose com dieta induzindo hiperlipidemia. Devido ao fato de que coelhos são muito sensíveis a dietas ricas em colesterol e acumulam grandes quantidades no plasma, a utilização destes animais como modelo experimental para avaliar o desenvolvimento de aterosclerose é de grande relevância, trazendo informação sobre fatores que contribuem para progressão e regressão aplicadas a situações humanas. Sendo assim, nessa revisão a função aterogênica do colesterol é mostrada em trabalhos que incluem o coelho como modelo experimental, uma vez que este animal tornou-se o mais popular modelo experimental de aterosclerose.

Many researches have been conducted in experimental models in order to study the development of atherosclerosis from hyperlipidemia-inducing diets. Since rabbits are very sensitive to cholesterol-rich diets and accumulate large amounts of cholesterol in their plasma, their use as experimental models to evaluate the development of atherosclerosis is highly relevant and brings information on factors that contribute to the progression and regression of this condition that can be applied to humans. As such, this review includes studies on the atherogenic function of cholesterol based on rabbits as the experimental model, since they have become the most largely used experimental model of atherosclerosis.

Cellular antiendotoxin activities of lung surfactant protein C in lipid vesicles.

The respiratory system is continuously exposed to airborne particles containing lipopolysaccharide. Our laboratory established previously that the hydrophobic surfactant protein C (SP-C) binds to lipopolysaccharide and to one of its cellular receptors, CD14. Here we examined the influence of SP-C, and of a synthetic analog, on some cellular in vitro effects of lipopolysaccharide. When associated with vesicles of dipalmitoylphosphatidylcholine, SP-C inhibits the binding of a tritium-labeled lipopolysaccharide to the macrophage cell line RAW 264.7. Under similar conditions of presentation, SP-C inhibits the mitogenic effect of lipopolysaccharide on mouse splenocytes, and inhibits the lipopolysaccharide-induced production of tumor necrosis factor-alpha by peritoneal and alveolar macrophages, and of nitric oxide by RAW 264.7 cells. In contrast, tumor necrosis factor-alpha production induced by a lipopeptide, and nitric oxide production induced by picolinic acid, were not affected by SP-C. The lipopolysaccharide-binding capacity of SP-C is resistant to peroxynitrite, a known mediator of acute lung injury formed by reaction of nitric oxide with superoxide anions. These results indicate that SP-C may play a role in lung defense; SP-C resists degradation under inflammatory conditions and traps lipopolysaccharide, preventing it from inducing production of noxious mediators in alveolar cells.

Histones: a novel class of lipopolysaccharide-binding molecules.

Unlike soluble and membrane forms of lipopolysaccharide (LPS)-binding proteins, intracellular LPS-binding molecules are poorly documented. We looked for such molecules in a murine lung epithelial cell line. Two proteins with LPS-binding activity were isolated and unambiguously identified as histones H2A.1 and H4 by mass spectrometry. Synthetic peptides representing partial structures indicated that the LPS binding site is located in the C-terminal moiety of the histones. Extending the study, we found that histones H1, H2A, H2B, H3, and H4 from calf thymus are all able to bind LPS. Bindings were specific, and affinities, determined by isothermal titration calorimetry, were (except for H4) higher than that of the LPS-binding antibiotic polymyxin B. In the presence of H2A the binding of LPS to the macrophage cell line RAW 264.7, and the LPS-induced production of TNF-alpha and nitric oxide by these cells, were markedly reduced. Histones may thus represent a new class of intracellular and extracellular LPS sensors.

Interaction of pulmonary surfactant protein C with CD14 and lipopolysaccharide.

In addition to their effects on alveolar surface tension, some components of lung surfactant also have immunological functions. We found recently that the hydrophobic lung surfactant protein SP-C specifically binds to the lipid A region of lipopolysaccharide (LPS). In this study, we show that SP-C also interacts with CD14. Four observations showed cross talk between the three molecules SP-C, LPS, and CD14. (i) Like LBP, SP-C allows the binding of a fluorescent LPS to cells expressing CD14 (the other surfactant components were ineffective). (ii) Recombinant radiolabeled CD14 and SP-C (or a synthetic analog of SP-C) interact in a dose-dependent manner. (iii) LPS blocks the binding of radiolabeled CD14 to SP-C-coated wells. (iv) SP-C enhances the binding of radiolabeled CD14 to LPS-coated wells. These results, obtained with native murine SP-C and with three synthetic analogs, suggest that LPS and CD14 interact with the same region of SP-C and that binding of SP-C modifies the conformation of CD14 or the accessibility of its LPS-binding site, allowing it to bind LPS. This ability of SP-C to interact with the pattern recognition molecule CD14 extends the possible immunological targets of SP-C to a large panel of microorganisms that can enter the airways.