Protective effect of thymic humoral factor on porcine serum-induced hepatic fibrosis and liver damage in Wistar rats.

INTRODUCTION: Immunomodulatory drugs have been reported to have anti-inflammatory and anti-fibrotic properties. Thymic humoral factor (THF), a peptide produced in the thymus, causes a potent immunomodulatory effect on different components of the immune system. OBJECTIVE: To evaluate the effect of THF on different stages of liver damage and fibrosis induced in rats through the administration of porcine serum (PS). MATERIAL AND METHODS: PS-induced liver fibrosis models serve as a primarily immunological mechanism in the development of liver damage and fibrosis. RESULTS: The intraperitoneal administration of THF in rats with PS-induced liver damage produced a reduction of ALT and AST after 60 days. Histopathological changes in liver sections showed an improved histological appearance and lower % of fibrosis after 60 days in liver damaged rats that received THF treatment. Serum IL-6 levels were visibly reduced by THF administration after 60 days and in comparison with rats that did not receive the treatment. This was due to an increment in serum IL-10 levels caused by the administration of THF, which appears to reduce the inflammatory process by decreasing immune response. CONCLUSION: THF had beneficial effects in combating liver damage and fibrosis processes in an autoimmune model of PS-induced liver fibrosis in rats.

Use of a graft of demineralized bone matrix along with TGF-ß1 leads to an early bone repair in dogs.

Tibia fractures are common in small animal practice. Over the past decade, improvements to animal internal fracture fixation have been developed. TGF-ß1 has been shown to be crucial in the development, induction and repair of bone. In present study, we investigate the effect of local application of a graft demineralized bone matrix (DBM) along with TGF-ß1 in a model of open osteotomy induced experimentally in dogs. Tibia fracture was brought about by using an open osteotomy model in young male dogs. Fracture repair was evaluated by a histological and biochemical analysis. Collagen content, proteolytic activity and urokinase-type plasminogen activator (uPA) expression were analyzed at the end of the study. Radiographic analysis, alkaline phosphatase and hematological evaluation were performed weekly. At the fifth week, there was an improvement and restoration of bone architecture in animals treated with a graft containing TGF-ß1 (5 ng/ml) compared with the control and graft groups, as was evidenced by the presence of an early formation of wide callus and bone regeneration. In addition, local application of TGF-ß1 led to an increase in collagen and proteolytic activity. More immunopositive osteoclast and mesenchymal cells were found in bone tissue from animals treated with TGF-ß1 as compared with the control group. No changes in alkaline phosphatase, hematological and clinical parameters were observed. This study shows that the combined use of DBM along with TGF-ß1 is able to improve and accelerate the bone repair.

Histamine augments beta2-adrenoceptor-induced cyclic AMP accumulation in human prostate cancer cells DU-145 independently of known histamine receptors.

Androgen-independent prostate cancer cells DU-145 express a number of G protein-coupled receptors, including histamine H1 receptors. There is evidence for the presence of beta-adrenoceptors in the human prostate, and in this work we set out to characterise the expression of beta-adrenoceptors by DU-145 cells, their linking to cyclic AMP (cAMP) formation and the possible modulation by histamine H1 receptors of beta-adrenoceptor function. Saturation [3H]-dihydroalprenolol binding indicated that DU-145 cells express moderate levels of beta-adrenoceptors (22.7+/-2.5 fmol/mg protein), which belong to the beta2-subtype as assessed by inhibition by the antagonists ICI-118,551 and CGP-20712A. Inhibition of [3H]-dihydroalprenolol binding by agonists (noradrenaline, adrenaline and isoproterenol) showed the presence of both high-(53-59%) and low-affinity binding sites. beta-Adrenoceptor stimulation with isoproterenol resulted in robust [3H]-cAMP accumulation (10-30-fold of basal, EC50 142 nM; pEC50 6.85+/-0.05). While not having effect of its own on basal [3H]-cAMP accumulation, histamine significantly augmented the beta2-adrenoceptor-induced response (overall effect 152+/-6% of isoproterenol alone) with EC50 1.35 microM (pEC50 5.87+/-0.06). This effect was independent of extracellular Ca2+, insensitive to antagonists/agonists at H1, H2 or H3/H4 receptors and mimicked by drugs containing an imidazole ring in their chemical structure and by imidazole itself. Taken together, our results show that in DU-145 cells histamine augments beta2-adrenoceptor-induced cAMP independently of the activation of known histamine receptors. The effect may involve other mechanisms such as allosteric modulation of beta2-adrenoceptors by the imidazole moiety of histamine.

Modulation of urokinase-type plasminogen activator by transforming growth factor beta1 in acetaldehyde-activated hepatic stellate cells.

The aim of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) induces the synthesis, release and gene expression of urokinase-type plasminogen activator (uPA) in hepatic stellate cells. In addition to stimulating collagen production, TGF-beta1 induced the morphological and phenotypical changes characteristic of hepatic stellate cell activation. However, these changes accentuated in cells previously activated with acetaldehyde. TGF-beta1 increased to 2-fold uPA activity in lysates from quiescent cells, and to 3.5-fold in activated cells, and induced uPA gene expression to the same extent in both activated and non-activated cells. TGF-beta1 had a modest stimulatory action on the release of uPA into the conditioned medium, but reduced acetaldehyde-induced release, as demonstrated by Western blot analysis. In accord, whereas TGF-beta1 produces no effect on uPA activity in the conditioned media from quiescent cells, it significantly reduces the stimulatory action of acetaldehyde. These results show that the activity and gene expression of uPA are regulated by both acetaldehyde and TGF-beta1 and that the proteolytic activity in the extracellular space is reduced by the influence of TGF-beta1. Further studies on the molecular mechanisms responsible for the regulation of the plasminogen system by TGF-beta1 and other molecules in the presence of acetaldehyde will contribute to a better understanding of the processes involved in fibrogenesis.

La proteólisis en la invasión y metástasis de la célula tumoral / Proteolysis in the invasion and metastases of the tumoral cell

En los últimos veinte años, ha habido considerable interés en comprender exactamente cuáles moléculas están involucradas en la patofisiología de la diseminación tumoral. Los resultados acumulados en ese tiempo indican que la propagación metastática del tumor representa la culminación de cambios malignos adquiridos durante la tumorigénesis. Uno de los hallazgos, que ha sido constante en esas observaciones, es la participación de las enzimas proteolíticas en los procesos de invasión y metástasis. En la actualidad se sabe que, para que la célula tumoral inicie la invasión del tejido adyacente y dé lugar a la metástasis, es necesaria toda una cascada de reacciones proteolíticas, en la cual participan serina, thiol y metaloproteasas. Se ha observado que algunas de esas enzimas proteolíticas se encuentran circulando, mientras que otras son sintetizadas y secretadas por las mismas células tumorales. También se sabe que existen varios inhibidores específicos de cada una de las familias de proteasas que pueden limitar la degradación de la matriz, y con esto inhibir la propagación tumoral. Este artículo resume una serie de evidencias relacionadas con la diseminación tumoral, observadas en modelos experimentales in vitro e in vivo, así como en diferentes cánceres que afectan al hombre, y hace énfasis en el papel de la proteólisis en la invasión y metástasis del cáncer.