Four whole-istic aspects of schistosome granuloma biology: fractal arrangement, internal regulation, autopoietic component and closure

This paper centers on some whole-istic organizational and functional aspects of hepatic Schistosoma mansoni granuloma, which is an extremely complex system. First, it structurally develops a collagenic topology, originated bidirectionally from an inward and outward assembly of growth units. Inward growth appears to be originated from myofibroblasts derived from small portal vessel around intravascular entrapped eggs, while outward growth arises from hepatic stellate cells. The auto-assembly of the growth units defines the three-dimensional scaffold of the schistosome granulomas. The granuloma surface irregularity and its border presented fractal dimension equal to 1.58. Second, it is internally regulated by intricate networks of immuneneuroendocrine stimuli orchestrated by leptin and leptin receptors, substance P and Vasoactive intestinal peptide. Third, it can reach the population of ± 40,000 cells and presents an autopoietic component evidenced by internal proliferation (Ki-67+ Cells), and by expression of c-Kit+ Cells, leptin and leptin receptor (Ob-R), granulocyte-colony stimulating factor (G-CSF-R), and erythropoietin (Epo-R) receptors. Fourth, the granulomas cells are intimately connected by pan-cadherins, occludin and connexin-43, building a state of closing (granuloma closure). In conclusion, the granuloma is characterized by transitory stages in such a way that its organized structure emerges as a global property which is greater than the sum of actions of its individual cells and extracellular matrix components.

Myelopoietic competence of stroma composed of hepatic granuloma-derived connective tissue cells or skin fibroblasts

1. Connective tissue cells isolated form hepatic granulomas (GR cells), induced in mouse liver tissue by schistosomal infection, are able to sustain myelopoiesis, while other connective tissue cells such as skin fibroblasts (SF) are not. 2. We compared the ability of SF and GR cells sustain in vitro proliferation of the FDC-P1 myeloid cell line, dependent upon IL-3 or GM-CSF. 3. Only the GR stroma susteined the proliferation of co-cultured FDC-P1 cells. RT-PCR analysis showed that both cell lines expressed the message for GM-CSF, but not for IL-3. We showed that GM-CSF was produced by, and remained bound to the cell layer through heparan sulfate; this growth factor could be released by high-salt treatment in a biologically active form from both cell types. The same activity could be restored to NaCl-treated GR cells, but not to SF, by incubation with recombinant murine GM-CSF. 4. These results indicate that the ability of connective tissue cells to sustain myelopoiesis depends directly upon the capapcity of their heparan sulfate-bearing molecules to bind and present the GM-CSF to the target cells in a biologically active form. Alternatively, a yet unidentified set of cell layer-associated molecules may be required for the positive or negative control of the membrane-bound GM-CSF

In vitro collagen synthesis by liver connective tissue cells isolated from schistosomal granulomas

Hepatic injury elicits an excessive deposition of extracellular matrix probably due to a loss of control mechanisms in mesenchymal cells in fibrotic lesions, or a local activity of growth factors. To study collagen synthesis in an in vitro model of fibrotic lesions, we isolated liver connective tissue cells (LCTC) from murine schistosomal granulomas in C3H/HeN mice. Collagen was quantified in culture supernatants using a sirius red dye assay. LCTC and skin fibroblasts (SF) secreted similar amounts of collagen per cell and secretion was inversely proportional to the cell density. Cells cultured at low density (10,000 cells/cm2) secreted two- to three-times more collagen per cell when compared to cells grown in high-density cultures (60,000 cells/cm2). Collagen secretion was stimulated by transforming growth factor-beta (TGF-beta) in both cell lines, but the response of LCTC was detected from 1 ng/ml on, while SF responded only to higher concentrations (2.5 and 5 ng/ml). These data do not support the hypothesis that cells from fibrotic livers have lost the normal control mechanisms and suggest that their control is disturbed locally by the presence of peptide growth factors during the development of fibrosis.

Bioquímica da esquistossomose mansônica: envolvimento dos siderossomos nos processos inflamatórios hepáticos / Biochemistry of schistosomiasis mansoni: involvement of siderosomes in hepatic inflammatory processes

Os processos inflamatórios que se desenvolvem durante as etapas avançadas da esquistossomose mansônica foram relacionados, com o acúmulo de siderossomos, a capacidade dos ions ferrosos/férricos de desencadearem a formaçäo de radicais livres e a peroxidaçäo de lipídios membranáceos, assim como à diminuiçäo da estabilidade das membranas dos diversos componentes do comportamento lisossômico hepático. Os lisossomos isolados de figados de camundongos infectados por 100 cercárias, com 80 e 100 dias de infecçäo, foram respectivamente, 2,5 e quase 4 vezes mais frágeis que os controles, isolados de figados de camundongos näo infectados. A presença de siderossomos em grande quantidade foi demonstrada por espectrometria aos raios-X

Effect of experimental Schistosomiasis on 14C-4-cholesterol esterification by mouse liver homogenate

The effect of experimental schistosomiasis mansoni on cholesterol esterification by mouse liver homogenate was studied using 14C-4-cholesterol. The reaction was carried out in 0.85 ml containing 10 nCi labelled cholesterol (I64 nmol as an albumin-stabilized emulsion) with 30 mg tissue homogenate in 176 mM sodium phosphate buffer, pH 7.1, containing 59 micronM oleic acid, 0.3 mM CoASH and 8.8 mM ATP. In experiments with liver from infected mice(N = 22), the percentage of cholesterol esterification was 6.9 + or - 0.7%/h. This rate was 52% less than that observed in normal mice (14.4 + or - 0.6%/h, N = 21). The decrease may be due to the existence of inhibitors of the cholesterol esterifying in the infected liver, increased hydrolysis of cholesteryl esters or a decrease in the synthesis of the enzyme acyl CoA:cholesterol acyl transferase by the infected liver

Bioquímica da esquistossomose mansônica: VII. Alteraçöes lipídicas das membranas lisossômicas durante a faze inicial da agressäo hepática / Biochemistry of schistosomiasis mansoni: VII. Changes of the lipid composition of lynsosomal membranes at the initialphase of liver injury

Com o intuito de se estudarem as alteraçöes nos teores lipídicos, constituintes das membranas lisossômicas, em fígados, durante a fase inicial da agressäo esquistossomótica, foram utilizados camundongos infectados com 30 cercárias e 30 dias de infecçäo. Os triaglicerídios passaram de 200 ñ 48 microng/mg de proteínas totais nos controles, para 165 ñ 22 microng/mg, nos infectados. Na mesma ordem também diminuiram o colesterol livre de 539 ñ 80, para 396 ñ 54 microng/mg; os ésteres do colesterol de 270 ñ 35, para 216 ñ 36 microng/mg e os colinafosfatídios de 44 ñ 5,7 para 31 ñ 4,9 microng/mg. Os serinafosfatídios, os etanolaminafosfatídios e os esfingofosfatídios aumentaram, respectivamente de 58 ñ 9,7 para 60 ñ 8,5, de 72 ñ 7,8 para 111 ñ 15,7 e de 36 ñ 4,9 para 63 7,1 microng/mg. Os ácidos graxos livres näo se alteram significativamente, passaram de 1,7 ñ 0,35 micronEq/g, nos controles, para 1,8 ñ 0,29 micronEq/g nos animais infectados. Esses resultados padecem indicar que na fase inicial de esquistossomose mansônica hepática, antes da formaçäo dos granulomas, säo detectadas alteraçöes importantes na constituiçäo lipídica das membranas do compartimento lisossônico. Elas, talvez, sejam devidas a produtos catabólicos, excretados por vermes imaturos ou adultos, presentes em vasos do sistema portal