New insights into the effects of irisin levels in HIV-infected subjects: correlation with adiposity, fat-free mass, and strength parameters

ABSTRACT Objective Patients infected with the human immunodeficiency virus (HIV) have an increased risk of metabolic disorders and alterations on irisin levels. Therefore, the purpose of the current investigation was to quantify the circulating irisin concentration in HIV-infected subjects under highly active antiretroviral therapy and to determine possible correlations between irisin levels with fat mass, fat-free mass, body mass index (BMI), and muscle strength. Subjects and methods Cross-sectional study of 10 men (36.7 ± 11.3 years) and 10 women (42.5 ± 10.3 years) infected with HIV, recruited from the Specialized Service Center in the State Center of Reference for High and Medium Complexity. Blood samples were collected to determine plasma irisin levels, glucose, HDL, total cholesterol, triglycerides, and LDL. Body composition (fat mass, fat-free mass) and anthropometrics (body mass index; BMI) were measured by bioelectrical impedance. Muscle strength was assessed using a mechanic hand dynamometer and one maximum repetition tests. Results Irisin levels correlated positively with fat mass (r = 0.67; p = 0.001) and BMI (r = 0.48; p = 0.036). In contrast, there was an inverse correlation between irisin levels and fat-free mass (r = -0.41; p = 0.008) and five strength parameters: right hand grip (r = -0.46; p = 0.044); left hand grip (r = -0.50; p = 0.027), relative hand grip (r = -0.79; p = 0.001), bench press (r = -0.58; p = 0.009), leg press (r = -0.40; p = 0.085), and biceps curl (r = -0.059; p = 0.009). Conclusion Irisin levels correlated positively with body fat and negatively with fat-free mass and strength parameters in HIV-infected patients. Female patients infected with HIV receiving highly active antiretroviral therapy have higher levels of irisin compared with men in a similar circumstance.

Human plasma fibronectin promotes proliferation and differentiation of odontoblast

Abstract Objective To assess the effect of fibronectin (Fn) and porcine type I collagen (PCOL) on odontoblast-like cells in vitro. Material and Methods Rat odontoblast-like cells (MDPC-23 cells) were inoculated and cultured on Fn-coated or type I collagen-coated substrates. Proliferation assay, alkaline phosphatase activity (ALP activity), mRNA expression of hard tissue-forming markers, and Alizarin red staining were investigated over a period of 10 days. Results Cells maintained a high proliferation activity on Fn and PCOL even at a low seeding concentration (0.5×104/mL) as demonstrated by CCK-8 assay. The proliferation activity of cells on Fn increases in a concentration-dependent manner while it reached a plateau after 10 µg/mL. Cells adopted long, thin and spindle shape on Fn(10-50) and PCOL. Parallel actin filaments were observed in MDPC-23 cells cultured on Fn and PCOL. ALP activity was markedly up-regulated on Fn and PCOL-coated surfaces. Importantly, gene expression of BSP (Fn10: 2.44±0.32; Fn20: 3.05±0.01; Fn30: 2.90±0.21; Fn40: 2.74±0.30; Fn50: 2.64±0.12; PCOL: 2.20±0.03) and OCN (Fn10: 2.52±0.23; Fn20: 2.28±0.24; Fn30: 2.34±0.21; Fn40: 2.34±0.25; Fn50: 2.20±0.22; PCOL: 1.56±0.16) was significantly enhanced on Fn and PCOL substrates as compared with control; moreover, expression of integrin beta 1 (ITGB1), an ubiquitous cell surface receptor was augmented in Fn(10-50) and PCOL groups simultaneously. In accordance with the ALP activity and gene expression data, calcific deposition in cells grown on Fn(10-50) and PCOL was observed as well. Conclusion Despite the limitation of this study, the findings indicate that a surface coating of Fn enhances the proliferation, differentiation and mineralization of odontoblast-like cells by activation of integrin beta 1 (ITG B1). The promoting effects of Fn on MDPC-23 cells were achieved at a comparatively lower coating concentration than type I collagen (300 µg/mL). Specifically, it is suggested that the optimum coating concentration of Fn to be 10 µg/mL.

Proliferation and osteogenic activity of fibroblasts induced with fibronectin

The aim of this study was to determine the proliferation and osteogenic activity of fibroblasts induced with fibronectin and their possible dose-dependent relationship. The fibroblasts obtained by tissue explants adherent method were induced with fibronectin at different concentrations of 0, 10, 20, 40, 60, and 80 μg/mL for 14 days. The 3H-thymidine and 3H-proline incorporation test was used to evaluate the synthesis of DNA and collagen by fibroblasts, respectively. The mineralized nodules and osteocalcin secretion, as vital osteogenic indicators, were detected with tetracycline labeling and 125I-labeled competitive immunoassay, respectively. Fibronectin significantly increased the synthesis of DNA and collagen by fibroblasts, especially at the concentration of 40 μg/mL (P<0.05). The increased secretion of osteocalcin in the supernatant was also statistically significant at the concentration of 40 μg/mL (P<0.05). The mineralized nodules with trabecula-like structure derived from induced fibroblasts were positive for tetracycline labeling. The granulation tissue-derived fibroblasts induced with fibronectin exhibited increased proliferative, functional and osteogenic potential. Fibroblasts are considered a possible in situ stem cell in tissue engineering.

Effects of fibronectin and type IV collagen on osteosarcoma cell apoptosis.

The aims of this study are the investigation of the effects of fibronectin and type IV collagen extracellular matrix proteins and the role of caspase-3 and -9 on cis-platin induced U2-OS apoptosis were studied. First the cytotoxic effects of cis-platin on cell system were investigated by colorimetric method and than morphological and ELISA analysis were used for determination of cell apoptosis when induced with cis-platin. In addition, after adhering the cells to fibronection or type IV collagen proteins, the apoptotic rate and the effects of caspase-3 and -9 were also investigated by ELISA in presence of specific inhibitors. U2-OS cells showed 20% cytotoxicity after treatment with 2.4 µM of cis-platin for 48 h. Morphological and the numerical data showed that cis-platin was able to induced apoptosis on cells as a dose-dependent manner. Caspase-3 and -9 inhibitors inhibited cis-platin-induced apoptosis in U2-OS cells, respectively. The binding of cells to 10 µg/mL of fibronectin but not type IV collagen enhanced the apoptosis about 2.5 fold that effects inhibited with caspase-3 inhibitor. The caspase-3 and -9 are involved in the apoptotic signals induced by cis-platin in U2-OS. The binding to fibronectin, but not type IV collagen enhanced the apoptotic response of U2-OS and fibronectin-dependent apoptosis was activated by caspase-3. These finding might be useful for patients to fight against osteosarcoma.

Cell adhesion by aqueous extract of human placenta used as wound healer.

Aqueous extract of human placenta, used as wound healer, has shown significant cell adhesion property on mouse peritoneal macrophages and P388D1 cultured macrophage cell line. This property was offered primarily by fibronectin type III like peptide present in the extract and is comparable to fibronectin on a molar basis. The peptide induce adhesion of cell through cell surface receptors having K(d) = 2.8 +/- 0.9 x 10(-5) M suggesting weak binding. This is in support of integrins receptors that typically exhibit low affinities. Cell adhesion was partially inhibited by Arg-Gly-Asp (RGD) peptide, anti-beta1 integrin suggesting that integrin beta1 receptors have roles to play in the process.

Modulación de la angiogenesis inducida por linfocitos por proteinas de la matriz extracelular / Modulation of angiogenesis induced by lymphocytes by extracellular matrix proteins

La neovascularización es uno evento importante en el desarrollo y crecimiento tumoral. La liberación de células tumorales en la circulación no se observa en la fase avascular del crecimiento tumroal. Los linfocitos de ratones portadores de tumor son capaces de inducir una respuesta angiogénica cuando se inoculan intradérmicamente en la piel de animales singenéicos. Esta respuesta recibe el nombre de SLIA. En este trabajo se estudia proteínas presentes en la matriz extracelular, colágeno y fibronectina (FN) pueden modificar la respuesta antiogênica inducida por linfocitos de ratones portadores de tumor S13. El tratamiento de los linfocitos con FN o con el péptido Gly. Arg. Glyp. Asp. inhibió la angiogénesis. Por el contrario el colágeno y el péptido Gly. Arg. Gly. Asp. Ser no modificaron la respuesta neovascular inducida por los linfocitos de portadores de tumor