Normal skin and hypertrophic scar fibroblasts differentially regulate collagen and fibronectin expression as well as mitochondrial membrane potential in response to basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) regulates skin wound healing; however, the underlying mechanism remains to be defined. In the present study, we determined the effects of bFGF on the regulation of cell growth as well as collagen and fibronectin expression in fibroblasts from normal human skin and from hypertrophic scars. We then explored the involvement of mitochondria in mediating bFGF-inducedeffects on the fibroblasts. We isolated and cultivated normal and hypertrophic scar fibroblasts from tissue biopsies of patients who underwent plastic surgery for repairing hypertrophic scars. The fibroblasts were then treated with different concentrations of bFGF (ranging from 0.1 to 1000 ng/mL). The growth of hypertrophic scar fibroblasts became slower with selective inhibition of type I collagen production after exposure to bFGF. However, type III collagen expression was affected in both normal and hypertrophic scar fibroblasts. Moreover, fibronectin expression in the normal fibroblasts was up-regulated after bFGF treatment. bFGF (1000 ng/mL) also induced mitochondrial depolarization in hypertrophic scar fibroblasts (P < 0.01). The cellular ATP level decreased in hypertrophic scar fibroblasts (P < 0.05), while it increased in the normal fibroblasts following treatment with bFGF (P < 0.01). These data suggest that bFGF has differential effects and mechanisms on fibroblasts of the normal skin and hypertrophic scars, indicating that bFGF may play a role in the early phase of skin wound healing and post-burn scar formation.

Normal skin and hypertrophic scar fibroblasts differentially regulate collagen and fibronectin expression as well as mitochondrial membrane potential in response to basic fibroblast growth factor.

Basic fibroblast growth factor (bFGF) regulates skin wound healing; however, the underlying mechanism remains to be defined. In the present study, we determined the effects of bFGF on the regulation of cell growth as well as collagen and fibronectin expression in fibroblasts from normal human skin and from hypertrophic scars. We then explored the involvement of mitochondria in mediating bFGF-induced effects on the fibroblasts. We isolated and cultivated normal and hypertrophic scar fibroblasts from tissue biopsies of patients who underwent plastic surgery for repairing hypertrophic scars. The fibroblasts were then treated with different concentrations of bFGF (ranging from 0.1 to 1000 ng/mL). The growth of hypertrophic scar fibroblasts became slower with selective inhibition of type I collagen production after exposure to bFGF. However, type III collagen expression was affected in both normal and hypertrophic scar fibroblasts. Moreover, fibronectin expression in the normal fibroblasts was up-regulated after bFGF treatment. bFGF (1000 ng/mL) also induced mitochondrial depolarization in hypertrophic scar fibroblasts (P < 0.01). The cellular ATP level decreased in hypertrophic scar fibroblasts (P < 0.05), while it increased in the normal fibroblasts following treatment with bFGF (P < 0.01). These data suggest that bFGF has differential effects and mechanisms on fibroblasts of the normal skin and hypertrophic scars, indicating that bFGF may play a role in the early phase of skin wound healing and post-burn scar formation.

Vitamin A deficiency injures liver parenchyma and alters the expression of hepatic extracellular matrix.

Vitamin A is an essential lipid-soluble nutrient that is crucial for morphogenesis and adult tissue maintenance. The retinoid homeostasis in the liver depends on a regular supply of vitamin A from an adequate dietary intake to preserve the normal organ structure and functions. This study focuses on the effect of vitamin A deficiency on the morphology and extracellular proteins expression of the liver in adult Wistar rats. Animals were fed with a normal (control group) or deficient vitamin A diet for 3 months. At the end of the experimental period, histological examination of the livers under light and electron microscopy revealed that vitamin A deficiency produced a loss of hepatocyte cord disposition with an irregular parenchymal organization. Abundant fat droplets were present in the cytoplasm of the hepatocytes. Elongated myofibroblastic-like cells with an irregular cytoplasmic process and without lipid droplets could be seen at the perisinusoidal space, where an elevated intensity of alpha smooth muscle actin (alpha-SMA) was observed. These results suggest that an activation of hepatic stellate cells (HSCs) occurred. Moreover, immunochemical methods revealed that vitamin A deficiency led to an increased expression of hepatic fibronectin, laminin and collagen type IV. We propose that vitamin A deprivation caused liver injury and that HSCs underwent a process of activation in which they produced alpha-SMA and synthesized extracellular components. These changes may be a factor predisposing to liver fibrosis. In consequence, vitamin A deprivation could affect human and animal health.

Undersulfation of proteoglycans and proteins alter C6 glioma cells proliferation, adhesion and extracellular matrix organization.

Proteoglycans are considered to be important molecule in cell-microenvironment interactions. They are overexpressed in neoplastic cells modifying their growth and migration in hosts. In this work we verified that undersulfation of proteoglycans and other sulfated molecules, induced by sodium chlorate treatment, inhibited C6 glioma cells proliferation in a dose-dependent way. This effect was restored by the addition of exogenous heparin. We could not detect significant cell mortality in our culture condition. The treatment also impaired in a dose-dependent manner, C6 cell adhesion to extracellular matrix (ECM) proteins (collagen IV, laminin and fibronectin). In addition, sodium chlorate treatment altered C6 glioma cell morphology, from the fibroblast-like to a more rounded one. This effect was accompanied by increased synthesis of fibronectin and alterations in its extracellular network organization. However, we could not observe modifications on laminin organization and synthesis. The results suggest an important connection between sulfation degree with important tumor functions, such as proliferation and adhesion. We suggest that proteoglycans may modulate the glioma microenvironment network during tumor cell progression and invasion.

La fibronectina y la adherencia de microorganismos patógenos / Fibronectin and the adherence of pathogenic microorganisms

La fibronectina (Fn) es uno de los principales componentes de la superficie celular, las matrices extracelulares y el plasma. La constituyen un dímero con dos cadenas polipeptícas de 250 kDa. Su estructura primaria está formada con base en unidades de repetición, originando los dominios de unión a diversas moléculas. La integrina Ó ß participa como el principal receptor celular de Fn. La fibronictina participa en procesos inmunológicos de fagocitosis, inflamación y opsonización, favoreciendo la depuración de bacterias y retos celulares. Juega un papel relevante en la cicatrización durante la hemostásis. En la superficie celular puede unirse a diferentes microorganismos, favoreciendo su colonización, siendo la primera etapa en la epatogénesis de diversas enfermedades infecciosas. En Staphylococcus aureus la proteína FnBp une al fragmento de 29 kDa de amino terminal de la Fn, sitio comparativo por Streptococcus pyogenes donde la proteína Sfb parece ser el ligando de la bacteria y no el ácido lipoteicóico (ALT). La Fn favorece la adherencia de bacterias gram positivas, su ausencia en la otofaringe favorece la colonización de bacterias gram negativas. Especies bacterianas de la cavidad orofaringea provocan la proteólisis de Fn y pueden participar indirectamente en la regulación de la flora cuando afectan los niveles de Fn en las superficies celulares. Treponema pallidum se une al sitio de reconocimiento celular de la Fn mediante una proteína semejante a la integrina (B 1) Entamoeba histolytica y schistosoma provocan una degradación de la Fn para poder invadir los tejidos epiteliales. Los parásitos intracelulares como Leishmania y Trypanosoma cruzi se adhieren a la Fn, utilizándola para facilitar su entrada a las células que infectan. La Fn puede unir virus y partículas virales favoreciendo la acción depuradora en este tipo de infecciones. Su amplia distribución en el organismo y su multifunsionalidad la hacen ser una proteína determinante en los procesos homeostásicos y de gran interés como un determinante en colonización e infección