Megavoltage radiotherapy effects on organs of the reticuloendothelial system

Purpose: To study the uptake capacity of cells from the reticuloendothelial system after irradiation with high-energy X-rays. Methods: Eighteen male Wistar rats were distributed in three groups: group A (n = 6): control, unirradiated animals studied alongside animals from group B; group B (n = 6) and group C (n = 6): animals irradiated and studied after 24 and 48 hours, respectively. The rats were anesthetized and placed on a 10 MV linear accelerator. Next, they were irradiated in the abdominal region, with 8 Gy. Twenty-four (groups A and B) and 48 hours later (group C), a colloidal carbon solution (1 mL/kg) was intravenously injected in the tail vein. Fifty minutes later, the spleens and livers were withdrawn and prepared to be studied. Kupffer cells and splenic macrophages containing carbon pigments were counted in an optical microscope. Arithmetic means were calculated for each group and compared among them. Results: X-rays were associated with a reduced number of Kupffer cells containing colloidal carbon, proliferation and enlargement of biliary ducts, hypoplasia, and hepatocyte necrosis. In the irradiated spleen, the colloidal carbon uptake was concentrated in the marginal zone around the white pulp, with an inexpressive uptake of pigments by macrophages from white and red pulps. Conclusions: The X-rays in the rat abdomen are associated with a reduction in the Kupffer cells uptake of colloidal carbon, hepatocyte disorders, bile duct proliferation, and splenic uptake of colloidal carbon concentrated in the marginal zone.

Aggregation of hepatic melanomacrophage centers in S. herzbergii (Pisces, Ariidae) as indicators of environmental change and well-being / [Agregação de centros de melanomacrófagos hepáticos em S. herzbergii (Pisces, Ariidae) como indicadores de mudança ambiental e de bem-estar]

The melanomacrophage centers (MMCs) in the liver of fish are indicators of environmental conditions, as they are involved in xenobiotic biotransformation. The objective of this study was to evaluate the number of MMC in the liver of juveniles and adults of Sciades herzbergii from areas with different levels of contamination. The fish were caught at three points (reference - A1, potentially impacted - A2 and contaminated - A3), in São José bay (Maranhão, Brazil), in four samples. The livers were subjected to the standard histological procedure and 5µm sections were stained with hematoxylin-eosin. In livers of A2 adult individuals (260.50±161.50 MMCs / mm²) they presented a greater number of MMCs when compared to A3 adults (60.00 ± 30.10 MMCs / mm²). Juveniles showed considerable values in A1 (100.00 ± 0.00 MMCs/mm²) and A2 (95.33 ± 33.00 MMCs / mm²) compared to juveniles in A3 (49.00±0.00 MMCs/mm²). These high values are unexpected for young people. The average number of MMC correlated with the rainy season in the region. The use of hepatic MMCs as a biomarker of exposure to pollutants, in particular substances from fisheries systems, such as ammonia and nitrite, proved to be adequate to differentiate areas with different levels of impacts.(AU)

Os centros melanomacrófagos (MMCs) no fígado de peixes são indicadores das condições ambientais, pois estão envolvidos na biotransformação xenobiótica. O objetivo deste estudo foi avaliar o número de MMC no fígado de juvenis e adultos de Sciades herzbergii de áreas com diferentes níveis de contaminação. Os peixes foram capturados em três pontos (referência - A1; potencialmente impactado - A2; e contaminado - A3), na baía de São José (Maranhão, Brasil), em quatro amostras. Os fígados foram submetidos ao procedimento histológico padrão e cortes de 5µm foram corados com hematoxilina-eosina. Em fígados de indivíduos adultos A2 (260,50±161,50 MMCs/mm²), eles apresentaram maior número de MMCs quando comparados aos adultos A3 (60,00±30,10 MMCs/mm²). Os juvenis apresentaram valores elevados em A1 (100,00 ± 0,00 MMCs/mm²) e A2 (95,33±33,00 MMCs/mm²) quando comparados aos juvenis em A3 (49,00±0,00 MMCs/mm²). Esses altos valores são inesperados para os jovens. O número médio de MMC correlacionou-se com a época chuvosa na região. A utilização de MMCs hepáticos como biomarcador de exposição a poluentes, em particular substâncias provenientes de sistemas pesqueiros, como amônia e nitrito, mostrou-se adequada para diferenciar áreas com diferentes níveis de impactos.(AU)

Preparation of Zoledronate liposome and its impact on apoptosis of Kupffer cells in rat liver

Abstract Purpose: To establish a method for the preparation of zoledronate liposome and to observe its effect on inducing the apoptosis of rat liver Kupffer cells. Methods: Zoledronate was encapsulated in liposomes, and then the entrapment rate was detected on a spectrophotometer. The prepared Zoledronate liposome (0.01 mg/mL) was injected into the tail vein of SD rats. Three days later, the number of Kupffer cells (CD68 positive) in rat liver tissue was detected by immunohistochemistry. Flow cytometry was used to detect the apoptosis rate of the isolated liver Kupffer cell cultured in vitro. Results: The entrapment rate of Zoledronate was 43.4±7.8%. Immunohistochemistry revealed that the number of Kupffer cells was 19.3±2.1 in PBS group and 5.5±1.7 in Zoledronate liposome group, with a significant difference (P<0.05). The apoptosis rate of Kupffer cells was 4.1±0.8% in PBS group, while it was 9±2.2% and 23.3±5.9% in Zoledronate liposomes groups with different concentrations of Zoledronate liposome (P<0.05). Conclusions: Zoledronate liposomes can effectively induce the apoptosis of Kupffer cells in vivo and in vitro, and the apoptosis rate is related to the concentration of Zoledronate liposome. To establish a rat liver Kupffer cell apoptosis model can provide a new means for further study on Kupffer cell function.

Estudo do papel das células de kupffer na modulação dos citocromos P450 hepáticos por estímulos inflamatórios

É conhecido que processos inflamatórios podem modular a expressão e atividade deenzimas CYPs. Não é claro, entretanto, o modo pelo qual estímulos inflamatórios regulam aexpressão dessas enzimas. Neste trabalho investigamos a hipótese de que as células deKupffer do fígado exerceriam um papel na modulação dos CYPs hepáticos em resposta àinflamação exacerbada ou sepse. O cloreto de gadolínio, é um inibidor seletivo das células deKupffer, conhecido por atenuar o quadro de inflamação exacerbada, quandoadministradopreviamente ao estímulo inflamatório, em diferentes modelos animais. Algunsautores sugeriram que as células de Kupffer atuariam como intermediários na modulação daatividade de CYPs hepáticos desencadeada por estímulos inflamatórios. Há estudos quesugerem que a diminuição da população das células de Kupfferatenua ou elimina a regulaçãodas CYPs hepáticas por estímulos inflamatórios.Além disso, estudos em culturas dehepatócitos in vitro, na ausência de células de Kupffer, tem constatado a regulação negativa daexpressão de CYPs hepáticas após estimulação com LPS. Nessa linha, o objetivo destepresente trabalho é investigar o papel das células de Kupffer na regulação da atividade deenzimas hepáticas de biotransformação de xenobióticos (CYPs) após estimulação inflamatóriacom LPS. Para isso, os níveis séricos de transaminases, e a histopatologia foram empregadospara avaliar o efeito do tratamento com diferentes doses de GdCl3sobre o tecido hepático.Noexperimento principal para investigar o papel das células de Kupffer, os ratos foram alocadosao acaso em quatro grupos. Foram quantificadosmarcadores bioquímicos no soro dos animaispara evidenciar danos ao tecido hepático causados pelos tratamentos e realizado o examehistopatológico...

It is known that inflammatory processes may modulate the expression and activity ofCYP enzymes. The mode by which inflammatory stimuli regulate CYP expression andactivity, however, remains unclear. Kupffer cells are resident macrophages in the liver andthus play an important role in a systemic inflammatory process or in sepsis. Gadoliniumchloride (GdCl3) has been reported to selectively kill an/or inhibit the activity of Kupffercells. Along this line, it has also been described that Gd decreases exacerbated inflammatoryresponses when it is administered prior to inflammatory stimuli in various animal models.Therole of Kupffer cells in the modulation of CYPs activity triggered by inflammatory stimuli,however, is not entirely clear in the literature. There are studies suggesting that a reduction inthe population of Kupffer cells attenuates the down-regulation of hepatic CYPs induced byinflammatory stimuli. However, GdCl3 was also described to decrease liver CYP activityirrespective of whether it depletes or not Kupffer cells. Moreover, in vitro studies showed thatLPS down-regulates the expression of CYP forms in hepatocyte cell lines in culture (in theabsence of Kupffer cells). To investigate whether Kupffer cells play a role in the regulation ofthe activity of liver xenobiotic biotransformation enzymes (CYPs) by inflammatorystimulation with LPS. The activity of transaminases in the blood serum (a marker for liverinjury) was determined and liver histopathology was evaluated in female Wistar rats. In a setof preliminary tests, rats were treated with different doses of GdCl3 or with LPS for selectingdoses and euthanasia time in the main experiment. In the main study experimental groups.Treatment associated liver injury was evaluated by levels of transaminases and alkalinephosphatase in the blood serum and by liver histopathology examination...

Regeneración hepática en enfermedad de hígado graso no-alcohólica / Liver regeneration in nonalcoholic fatty liver disease

La esteatosis hepática es el acúmulo de grasa en los hepatocitos, que puede ser la consecuencia del proceso de regeneración hepática o de procesos patológicos como la enfermedad del hígado graso alcohólica y no-alcohólica. A pesar de su importancia, en ambos casos el mecanismo exacto en que la esteatosis influye en la regeneración hepática es escasamente comprendido. Estudios previos han demostrado que los pacientes que presentan hígado graso expresan una regeneración hepática dispar, posiblemente debido a la acumulación de especies reactivas de oxígeno generada por procesos inflamatorios ocasionados por activación de las células de Kupffer. En este artículo se revisan distintos factores que afectan la regeneración hepática, tratando de comprender el mecanismo involucrado en la regeneración dispar en hígados con esteatosis ocasionada por una enfermedad de hígado graso no-alcohólica.

Steatosis is the accumulation of fat in hepatocytes, which may be the result of liver regeneration or pathological processes such as alcoholic and nonalcoholic fatty liver disease. Despite its importance, in both cases the exact mechanism that prevails in fatty liver regeneration is poorly understood. Previous studies have shown that patients with fatty liver express dispar regeneration, possibly due to the accumulation of reactive oxygen species generated by inflammatory processes caused by activation of Kupffer cells. In this article we review several factors that affect liver regeneration, trying to understand the underlying mechanism of dispar regeneration in fatty liver as a consequence of nonalcoholic fatty liver disease.

O transplante de células mononucleares de medula óssea contribui para o remodelamento da matriz extracelular durante a regeneração do fígado em ratos com fibrose hepática induzida por ligadura do ducto biliar / Bone marrow mononuclear cells transplantation contributes to extracelular matrix remodelling during liver regeneration in rats with hepatic fibrosis induced by bile duct ligation

A fibrose hepática é o resultado de uma lesão crônica, com a ativação de células inflamatórias e fibrogênicas no fígado, as quais levam a um acúmulo excessivo de proteínas de matriz extracelular (MEC). Essas alterações resultam na morte de células do fígado, com desorganização e perda da função do parênquima hepático. A cirrose é o estágio avançado da fibrose, e culmina na falência hepática, uma condição potencialmente fatal cujo único tratamento efetivo é o transplante de fígado, o qual é limitado pela disponibilidade de órgãos. Na busca por terapias alternativas visando a regeneração hepática, o transplante de células mononucleares de medula óssea (CMMO) mostrou resultados benéficos e promissores em modelos animais e alguns protocolos clínicos. Entre essas células, estão as células-tronco hematopoiéticas e mesenquimais, que apresentam potencial regenerativo e modulador da resposta inflamatória. Este estudo pretendeu avançar na compreensão dos mecanismos pelos quais as CMMO podem ajudar na regeneração hepática. Ratos com fibrose hepática induzida por ligadura do ducto biliar (LDB) foram transplantados com CMMO e comparados com ratos com fibrose sem transplante e ratos normais. Parâmetros hepáticos como componentes da MEC (colágeno total, colágenos tipos I e IV, laminina, metaloproteinases de matriz – MMPs), componentes celulares (células fibrogênicas, células de Kupffer e colangiócitos) e enzimas hepáticas foram analisados por microscopia de luz, microscopia confocal, western blotting e espectrofotometria. Os resultados mostraram que o transplante de CMMO contribui para a regeneração hepática de maneira global, (a) diminuindo o acúmulo de colágeno e laminina; (b) aumentando a produção de MMPs que favorecem o remodelamento da MEC, principalmente por células de Kupffer; (c) normalizando a quantidade de colangiócitos e diminuindo a quantidade de células fibrogênicas; e (d) normalizando os níveis sanguíneos das enzimas hepáticas...

Liver fibrosis results from a chronic injury, with the activation of hepatic inflammatory and fibrogenic cells, which lead to an excessive extracellular matrix (MEC) protein accumulation. These alterations result in the death of liver cells, along with disorganization and loss of function of the hepatic parenchyma. Cirrhosis is the advanced stage of fibrosis, and culminates in hepatic failure, a potentially fatal condition whose only effective treatment is liver transplantation, which is limited by organ shortage. Amid the search for alternative therapies aiming hepatic regeneration, bone marrow mononuclear cell (CMMO) transplantation has shown promising and benefic results in animal models and some clinical protocols. Amongst these cells are hematopoietic and mesenchymal stem cells, which present regenerative potential and modulate inflammatory response. This study aimed to add knowledge on the mechanisms by which CMMO may prompt hepatic regeneration. Rats with liver fibrosis induced by bile duct ligation (LDB) were transplanted with CMMO and compared to fibrotic and normal rats without transplantation. Hepatic parameters such as MEC components (total collagen, collagens types I and IV, laminin and matrix metalloproteinases – MMPs), cellular components (fibrogenic and Kupffer cells, cholangiocytes) and liver enzymes were analyzed through confocal, fluorescence and light microscopy, western blotting and spectrophotometry. Results showed that CMMO contribute to liver regeneration globally, (a) reducing collagen and laminin accumulation; (b) increasing MMP production, specially by Kupffer cells, that favor MEC remodeling; (c) normalizing cholangiocyte numbers and reducing fibrogenic cells; and (d) normalizing plasma levels of hepatic enzymes...

El comportamiento del factor de necrosis tumoral alfa e interleucina 6 en lesiones de vías biliares postcolecistectomía / Tumor necrosis factor-alpha and interleukin-6 levels among patients suffering a bile duct injury during cholecystectomy

Background: During cholecystectomy, the bile duct may be injured. When this complication occurs, Kupffer cells are activated and produce tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL6) to phagocyte toxic products Aim: To measure serum levels of TNF-α and IL-6 among patients that suffered a bile duct injury after a cholecystectomy. Patients and Methods: Serum levels of TNF-α and IL-6 were measured prior to the bile-enteric derivation and after one year of follow up, in 31 patients that had a complete bile duct obstruction after open or laparoscopic cholecystectomy and in 5 healthy controls. Results: At baseline TNF-α levels in healthy subjects and patients with bile duct injury were 0 and 43.9 ± 2.9 ng/mL, respectively (p < 0.01). At one year of follow up, TNF-á became undetectable among patients. At baseline, the values for IL-6 among healthy controls and patients were 3.0 ± 2.0 and 72.0 ± 94.7 pg/mL respectively, (p < 0,004). After one year of follow up, IL-6 levels decreased to 6.4 ± 0.3 pg/mL among patients. Conclusions: TNF-α and IL-6 levels were elevated before bile-enteric derivation among patients with bile duct injury and became normal one year later.

El hígado como órgano inmunológico / The liver and immune organ

La prevalencia de enfermedades hepáticas a nivel mundial registra cifras alarmantes. Solo la infección por malaria afecta a 500 millones de personas por año a nivel mundial. Enfermedades de etiología viral como hepatitis B y C, contribuyen al aumento de la casuística y por su caracter de patologías de tipo crónico evolucionan a formas severas como la fibrosis o los procesos neoplásicos. La relevancia del hígado como órgano central en la maquinaria metabólica del organismo y como clave partícipe de la respuesta inflamatoria sistémica, indican la necesidad de preservar sus capacidades funcionales.

O papel de macrófagos exsudativos e residentes do fígado (células de Kupffer) durante a infecção experimental com Leishmania (Leishmania) infantum / The role of macrophages and exudative residents of the liver (Kupffer cells) during experimental infection with Leishmania (Leishmania) infantum

No fígado, a atividade microbicida dos macrófagos infectados por Leishmania (Leishmania) infantum, com a finalidade de eliminar os parasitos intracelulares, causa uma citotoxicidade extracelular nos hepatócitos. Esta citotoxicidade gera importantes alterações morfológicas e funcionais nas células parenquimais hepáticas. A produção destes mediadores ocorre por duas vias principais, gerando uma grande quantidade de mediadores no meio extracelular. A via independente de oxigênio é caracterizada pela secreção de peptidases. As três classes de peptidases apresentam suas atividades proteolíticas aumentadas no momento de maior atividade microbicida pelos macrófagos, indicando a contribuição destas peptidases ao fenômeno, particularmente as metalopeptidases. A forma ativa da metalopeptidase 9 (85kDa) foi detectada no momento de maior atividade pelos macrófagos, mostrando que ela pode contribuir para os desarranjos na matriz extracelular importante para a homeostase das células em cultura. Nenhuma atividade proteolítica das amastigotas foi relacionada com o fenômeno. Amastigotas axênicas foram obtidas a partir de uma metodologia que permite a purificação de 100% de formas puras em um curto período em cultura (4 dias). Estas amastigotas apresentaram características morfológicas e bioquímicas idênticas quando comparadas com as amastigotas intracelulares obtidas de animais experimentais. Elas apresentaram o mesmo perfil de infecção nos macrófagos, o que mimetiza as condições de infecção in vivo. A via dependente de oxigênio se caracteriza pela liberação de espécies reativas de nitrogênio (RNS) e oxigênio (ROS). Células de Kupffer murinas foram estabelecidas neste trabalho e constatamos que estas produziram quantidades menores de RNS em comparação aos macrófagos peritoneais durante a infecção por amastigotas de Leishmania infantum. Isso deve estar correlacionado com o perfil de citocinas gerado nos macrófagos residentes do fígado infectados, com grandes quantidades de IL-10 e níveis significativamente mais baixos de TNF-alfa em comparação aos macrófagos peritoneais. A infecção por amastigotas de Leishmania infantum não estimulou a produção de ROS nas co-culturas formadas de Kupffer/hepatócitos e consequentemente, as transaminases hepáticas não se apresentaram aumentadas, indicando que danos extracelulares não ocorreram. Portanto, os danos nos hepatócitos só surgiram na presença de ROS e RNS secretados pelos macrófagos infectados, pois levam a formação de peroxinitrito. O tratamento com ácido úrico, varredor de peroxinitrito, mostrou que esta molécula é a grande responsável pela citotoxicidade extracelular encontrada nos hepatócitos. Sendo assim, os macrófagos exsudativos que chegam ao fígado apresentam suas vias microbicidas funcionantes, sendo os responsáveis pela eliminação dos parasitos mas também responsáveis pelos danos hepáticos, enquanto as células de Kupffer devem estar mais relacionadas com a apresentação antigênica e modulação da resposta imune adaptativa.

Aplicación de la técnica de aclaramiento del carbón coloidal en sangre periférica en la evaluación de la actividad inmunomoduladora de dos productos naturales / Applications of the colloidal carbón clearence technique in peripheral blood in the evaluation of the immunomodulator activity of two natural products

En el presente trabajo se evaluó el efecto de dos productos naturales en la actividad in vivo de los macrófagos esplénicos y las células de Kupffer, en diferentes sistemas experimentales, por medio de la prueba de aclaramiento de carbón coloidal en sangre periférica. Los resultados evidenciaron el efecto estimulador de un hidrolizado proteico de la microalga Chlorella vulgaris 87/1 sobre el sistema monocito-macrófago, administrado como suplemento a ratones malnutridos, y de extractos obtenidos de setas comestibles Pleurotus spp. en tres biomodelos de inmunodeficiencias secundarias (inducida por ciclofosfamida, por exposición a radiaciones ionizantes y por malnutrición proteico-energética). En los animales tratados con los productos se observó un menor tiempo de vida media de las partículas de carbón coloidal en sangre, lo que es una evidencia de la actividad inmunopotenciadora de ambos biopreparados y de la aplicabilidad de la técnica en cuestión.

In this paper, the effect of two natural products in the activity in vivo of the splenic macrophages and the Kupffer's cells was evaluated in different experimental systems by means of the colloidal carbon clearance test in peripheral blood. The results evidenced the stimulating effect of a protein hydrolizate of the microalga Chlorella vulgaris 87/1 on the monocyte-macrophagic system, administered as a supplement to malnourished mice, and of extracts obtained from edible mushrooms Pleurotus spp. in three biomodels of secondary immunodeficiencies (induced by cyclophosphamide, by exposure to ionizing radiations and by protein-energy malnutrition). In the animals treated with the products, it was observed a shorter time of mean life of the particles of colloidal carbon in blood, which shows the immunopotentiating activity of both biopreparations and of the applicability of the technique.

O papel da oxigenação hiperbárica na estrutura do fígado e baço após ligadura das veias hepáticas: estudo em ratos / The role of hyperbaric oxygenation in the liver and spleen structure after hepatic vein ligation: study in rats

OBJETIVO: Avaliação morfológica do fígado e baço de ratos submetidos à oxigenoterapia hiperbárica após a ligadura das veias hepáticas. MÉTODO: Foram utilizados 30 animais machos adultos da espécie Holtzman, distribuídos aleatoriamente em dois grupos de 15 animais cada, assim designados: grupo 1 - ligadura das veias hepáticas; grupo 2 - ligadura das veias hepáticas associada à oxigenoterapia hiperbárica. Todos os animais foram submetidos à anestesia geral por meio de solução contendo cloridrato de cetamina (40 mg/ml) e cloridrato de meperidina (10 mg/ml) na dose de 50 mg/kg/peso, laparotomia mediana e ligadura das veias hepáticas. A oxigenoterapia hiperbárica foi aplicada nos animais do grupo 2, a partir da oitava hora do pós-operatório, por 120 minutos, sendo 90 minutos sob pressão de 2,5 atmosferas e 15 minutos no início e final da terapêutica, para promover a compressão e descompressão gradativa no período de 20 dias consecutivos. No 21° dia de pós-operatório, os animais foram mortos por inalação de éter e submetidos à laparotomia e extirpação dos fígados e baços para exame histológico. Foram comparados os resultados da histologia hepática e esplênica aplicando-se o teste exato de Fisher, considerando-se a diferença significante de P < 0,05. RESULTADOS: Os exames histológicos dos fígados e baços dos animais dos grupos 1 e 2 mostraram as seguintes alterações: presença de trombose nas veias hepática, porta e centro-lobular em cinco (33,3 por cento) animais do grupo 1 e ausência no grupo 2; presença de necrose dos hepatócitos caracterizada como acentuada em sete animais (46,7 por cento) e leve em oito (53,3 por cento) animais do grupo 1, enquanto que, em todos os animais do grupo 2, esta alteração foi caracterizada como leve; presença de células de Kupffer muito proeminentes e hipertrofiadas em 14 (93,3 por cento) animais do grupo 1 e pouco proeminentes e hipertrofiadas em todos os animais do grupo 2; congestão da polpa vermelha considerada acentuada em seis (40 por cento) e moderada em nove (60 por cento) animais do grupo 1 e em todos os animais do grupo 2; hemossiderose moderada ou acentuada em 14 (93,3 por cento) animais do grupo 1 e leve em todos os animais do grupo 2. As análises estatísticas realizadas entre os dois grupos mostraram diferenças significativas em todas a variáveis estudadas (P < 0,05)...

Liver cirrhosis and hepatic stellate cells / Cirrose hepática e células estreladas do figado

The cirrhosis represents the final stage of several chronic hepatic diseases and it is characterized by the presence of fibrosis and morphologic conversion from the normal hepatic architecture into structurally abnormal nodules. In the evolution of the disease there is loss of the normal vascular relationship and portal hypertension. There are also regenerative hepatocelular alterations that become more prominent with the progression of the disease. The liver transplantation continues to be the only therapeutic option in cases of disease in terminal phase. The hepatic stellate cells (HSC) are perisinusoidal cells that store vitamin A and produce growth factors, citocins, prostaglandins and other bioactive substances. They can suffer an activation process that convert them to cells with a phenotype similar to myofibroblasts. When activated, they present increased capacity of proliferation, mobility, contractility and synthesis of collagen and other components of extracelular matrix. They possess cytoplasmic processes adhered to sinusoids and can affect the sinusoidal blood flow. HSC are important in pathogenesis of fibrosis and portal hypertension.

A cirrose representa o estágio final de diversas doenças hepáticas crônicas e é caracterizada pela presença de fibrose e conversão da arquitetura hepática normal em nódulos estruturalmente anormais. Na evolução da doença ocorre perda da relação vascular normal e hipertensão portal. Há também alterações regenerativas hepatocelulares que se tornam mais proeminentes com a progressão da doença. O transplante hepático permanece como a única opção terapêutica nos casos de doença em fase terminal. As células estreladas hepáticas (CEH) são células perisinusoidais que armazenam vitamina A e produzem fatores de crescimento, citocinas, prostaglandinas e outras substâncias bioativas. Podem sofrer um processo de ativação para um fenótipo semelhante a miofibroblastos. Quando ativadas apresentam maior capacidade de proliferação, motilidade, contractilidade, síntese de colágeno e componentes da matriz extracelular. Possuem processos citoplasmáticos aderidos aos sinusóides e podem afetar o fluxo sangüíneo sinusoidal. As CEH são importantes na patogênese da fibrose e hipertensão portal.

A molecular view of liver regeneration / Uma visão molecular da regeneração hepática

The purpose of this review was to carry out an analysis of the liver regenerative process focusing on the molecular interactions involved in this process. The authors undertook a review of scientific publications with a focus on the liver regeneration.The cellular processes involved in liver regeneration require multiple systematic actions related to cytokines and growth factors. These interactions result in the initiation of mitogenic potential of the hepatocytes. The action of these modulators in the regenerative process require a processing in the extra-cellular matrix. Serines and metal proteins are responsible for the bio availability of cytokines and growth factors so that they can interact as receptors in the cellular membrane generating signaling events for the beginning and end of the liver regenerative process. The exact mechanism of interaction between cells, cytokines and growth factors is not well established yet. A series of ordered events that result in the hepatic tissue regeneration has been described. The better understanding of these interactions should provide a new approach of the treatment for liver diseases, aiming at inducing the regenerative process.

O objetivo desta revisão foi desenvolver uma análise do processo regenerativo do fígado, focando as interações moleculares envolvidas neste processo.Os processos celulares envolvidos na regeneração hepática requerem múltiplas ações sistemáticas relacionadas com citoquinas e fatores de crescimento. Estas interações resultam na iniciação do potencial mitogênico dos hepatócitos. A ação destes moduladores do processo regenerativo necessita de processamento no meio extra celular. As serinas e metaloproteínas são responsáveis pela biodisponibilização de citoquinas e fatores de crescimento, para que então possam interagir com receptores na membrana celular gerando os eventos sinalizadores para o inicio e o término do processo regenerativo hepático.O exato mecanismo de interação entre células, citoquinas e fatores de crescimento não está bem estabelecido. Tem-se descrito uma série de eventos ordenados que resulta na regeneração do tecido hepático. O melhor entendimento destas interações leva a uma nova abordagem de tratamento para doenças hepáticas, objetivando a indução do processo regenerativo.

Possible roles of the hereditary hemochromatosis protein, HFE, in regulating cellular iron homeostasis

Hereditary hemochromatosis (HH) is the most common inherited disorder in people of Northern European descent. Over 83 percent of the cases of HH result from a single mutation of a Cys to Tyr in the HH protein, HFE. This mutation causes a recessive disease resulting in an accumulation of iron in selected tissues. Iron overload damages these organs leading to cirrhosis of the liver, diabetes, cardiomyopathy, and arthritis. The mechanism by which HFE influences iron homeostasis in cells and in the body remains elusive. Lack of functional HFE in humans produces the opposite effects in different cell types in the body. In the early stages of the disease, Kupffer cells in the liver and enterocytes in the intestine cells are iron depleted and have low intracellular ferritin levels, whereas hepatocytes in the liver are iron overloaded and have high intracellular iron levels. This review gives the background and a model as to possible mechanisms of how HFE could exert different effects on iron homeostasis in different cell types.

Papel das células estelares na fibrose hepática / Stellate cell and hepatic fibroses

RESUMO: As células estelares (células de Itpo) são células acumuladoras de vitamina A no fígado, desempenhando uma ação ativa nos mecanismos de injúria, regeneração e fibrose hepática. As células estelares sintetizam colágeno e tecido conjuntivo, responsáveis pela sustentação do parênquima hepático, bem como no fluxo sangüíneo e perfusão dos hepatócitos. Foram observadas a expressão de antígenos de linhagens celulares diferentes, como a proteína ácida glial-fibrilar e a actina de músculo liso, caracterizando fases diferentes de ativação das células estelares. Estudos têm demonstrado que o nível de vitamina A acumulado pode modular a síntese e depósito de colágeno uma vez que o acúmulo de retinol nas células estelares reduz a síntse de colágeno, no entanto, o excesso de vitamina A aumenta a sensibilidade do fígado a agentes hepatotóxicos, podendo suprimir a fibrose hepática.

Disfunción hepática en sepsis / Hepatic dysfunction during sepsis

La disfunción hepática en sepsis corresponde a la alteración de la función hepatocelular que se produce en el síndrome de respuesta inflamatoria sistémica (SRIS), se asocia a un mal pronóstico sobre todo cuando se manifiesta en el contexto de falla orgánica múltiple (FOM), y su mortalidad es muy elevada cuando existen más de tres órganos comprometidos. Las manifestaciones clínicas se presentan habitualmente después de la segunda semana de evolución, con elevación discreta de las aminotransferasas, fosfatasas alcalinas y de la gamaglutamiltranspeptidasa, lo más característico es la elevación de la bilirrubina incluso hasta sobre 10 mg/dl lo cual se asocia a un mal pronóstico. Generalmente los valores de protrombina se encuentran conservados, incluso en la etapa tardía de la sepsis. Sin embargo, la disfunción hepática en SRIS se presenta como una alteración global de la función hepática donde la capacidad detoxificadora de toxinas y bacterias está disminuida, y una gran carga de endotoxinas proveniente de la circulación esplácnica perpetúa la cadena inflamatoria que caracteriza al SRIS y a la FOM. No existe una terapia específica para disfunción hepática en sepsis sin embargo son importantes la etapa de reanimación inicial, la terapia antibiótica, también la iniciación precoz de la nutrición enteral para evitar el sobrecrecimiento bacteriano y disminuir la oferta de endotoxinas. Terapias como la proteína C activada recombinante surgen como promisorias, pero deben realizarse estudios controlados para establecer su verdadero lugar como terapia validada en sepsis grave.

The hepatic clearance of recombinant tissue-type plasminogen activator decreases after an inflammatory stimulus

We have shown that tissue-type plasminogen activator (tPA) and plasma kallikrein share a common pathway for liver clearance and that the hepatic clearance rate of plasma kallikrein increases during the acute-phase (AP) response. We now report the clearance of tPA from the circulation and by the isolated, exsanguinated and in situ perfused rat liver during the AP response (48-h ex-turpentine treatment). For the sake of comparison, the hepatic clearance of a tissue kallikrein and thrombin was also studied. We verified that, in vivo, the clearance of 125I-tPA from the circulation of turpentine-treated rats (2.2 + or - 0.2 ml/min, N = 7) decreases significantly (P = 0.016) when compared to normal rats (3.2 + or - 0.3 ml/min, N = 6). The AP response does not modify the tissue distribution of administered 125I-tPA and the liver accounts for most of the 125I-tPA (>80 percent) cleared from the circulation. The clearance rate of tPA by the isolated and perfused liver of turpentine-treated rats (15.5 + or - 1.3 µg/min, N = 4) was slower (P = 0.003) than the clearance rate by the liver of normal rats (22.5 + or - 0.7 µg/min, N = 10). After the inflammatory stimulus and additional Kupffer cell ablation (GdCl3 treatment), tPA was cleared by the perfused liver at 16.2 + or - 2.4 µg/min (N = 5), suggesting that Kupffer cells have a minor influence on the hepatic tPA clearance during the AP response. In contrast, hepatic clearance rates of thrombin and pancreatic kallikrein were not altered during the AP response. These results contribute to explaining why the thrombolytic efficacy of tPA does not correlate with the dose administered

Increased sleeping time after pentobarbital anesthesia in rats treated with intravenous injection of BCG

Intravenous injection of BCG in rats induces protection against liver cell necrosis produced by CCl4. Impairment of hepatic mixed function oxidases by cytokines produced by activated Kupffer cells is the mechanism proposed to explain that protection. To verify the function of hepatic mixed function oxidases after Kupffer activation, the sleeping time after sodium pentobarbital anesthesia was evaluated in rats after intravenous injection of BCG. Male adult albino rats received BCG (50 mug, intravenous) and 48 h or 6 days after were anestethized with sodium pentobarbital (33 or 66 mg/g i.p.). The sleeping time was measured from the beginning of sleep until animal started having spontaneous movement and stand up on the forepaws. The results showed that the animals treated with BCG presented a significative increase in the sleeping time, indicating reduced inactivation of the pentobarbital, an indirect evidence of inhibittion of mixed function oxidase system. BCG treated rats showed hepatic and splenomegaly, both 48 and 6 days after treatment. Histology showed increase in number of mononuclear cells in the sinusoids in the liver and in the red pulp of the spleen 48 h after injection. Small epitheliod granulomas scattered in the hepatic lobules and in the red pulp were observed in rats killed six days after the BCG injection. Hepatocyte injury, induced by activated macrophages, would be not responsible for the reduced pentobarbital inactivation, because at six days there were several granulomas scattered in lobules, but the increase of sleep time in this group was similar to that observed in rats 48 h after injection of BCG. These results demonstrate that activation of Kupffer cells with BCG induces impairment of mixed function oxidase system soon as 48 h after injection of activator, probably due to production of IL-1, IL-6 and TNF alpha by activated Kupffer cells and other mononuclear cells migrated to the liver.

Monoassociation with Lactobacillus acidophilus UFV-H2b20 stimulates the immune defense mechanisms of germfree mice

Probiotics are formulations containing live microorganisms or microbial stimulants that have some beneficial influence on the maintenance of a balanced intestinal microbiota and on the resistance to infections. The search for probiotics to be used in prevention or treatment of enteric infections, as an alternative to antibiotic therapy, has gained significant impulse in the last few years. Several studies have demonstrated the beneficial effects of lactic acid bacteria in controlling infection by intestinal pathogens and in boosting the host's nonspecific immune response. Here, we studied the use of Lactobacillus acidophilus UFV-H2b20, a lactic acid bacterium isolated from a human newborn from Viçosa, Minas Gerais, Brazil, as a probiotic. A suspension containing 108 cells of Lactobacillus acidophilus UFV-H2b20 was inoculated into groups of at least five conventional and germfree Swiss mice to determine its capacity to stimulate the host mononuclear phagocytic activity. We demonstrate that this strain can survive the stressing conditions of the intestinal tract in vivo. Moreover, the monoassociation of germfree mice with this strain for seven days improved the host's macrophage phagocytic capacity, as demonstrated by the clearance of a Gram-negative bacterium inoculated intravenously. Monoassociated mice showed an undetectable number of circulating E. coli, while 0.1 percent of the original inoculum was still present in germfree animals. Mice treated with viable or heat-killed Lactobacillus acidophilus UFV-H2b20 presented similarly improved clearance capacity when compared with germfree controls. In addition, monoassociated mice had twice the amount of Kupffer cells, which are responsible for the clearance of circulating bacteria, compared to germfree controls. These results suggest that the L. acidophilus strain used here stimulates a nonspecific immune response and is a strong candidate to be used as a probiotic

Kupffer cell activation with BCG, Corynebacterium parvum or zymosan protects against acute liver injury induced by carbon tetrachloride in rats

Kupffer cells have been implicated in the pathogenesis of liver injury, but there is controversy about the effects of activation of these cells on the hepatotoxicity of chemicals and endotoxin. It has been shown that injection of Corynebacterium parvum in rats induces macrophage activation that protects against toxic effects of carbon tetrachloride and acetaminophen, five days after injection, and this protection is due to inhibition of microsomal oxidizing enzimes and increased production of glutathion. To verify if the protective effect occurs soon after Kupffer cell activation, with different activators, male albino rats were treated with intravenous injection of BCG (0.5 ml with 7.5 10(8) bacilli), Corynebacterium parvum (30 mg/kg) or zymosan (7.5.10(6) yeast cells). Fourty-eight hours after the injection of one of the macrophage activators, the animals and rats treated with intravenous injection of saline (controls) received carbon tetrachloride by subcutaneous route (1 ml/kg of CCl(4), 3:1 in soybean oil). Fourty-eight hours after the animals were killed after ether anesthesia and fragments of the liver were fixed, paraffin embedded and the sections stained with hematoxylin and eosin. A Weibel grid with 168 points was used to estimate the percent volume of necrosis and severe hydropic degeneration. The results showed that the volume density of necrosis and severe hydropic degeneration were significatively lesser in rats treated with the three Kupffer cells activators. The protection was greater with BCG and Corynebacterium parvum than with zymosan. These results confirm that activation of Kupffer cell with three different activators can induce protection against liver cell injury produced by carbon tetrachloride in rats soon as 48 h after injection of activators.