Objective: Children and adolescents with type 1 (insulin-dependent) diabetes mellitus (T1DM) show several impairment of bone metabolism and structure, resulting in a higher risk of decreased bone mass and its related complications later in life. Alterations of the nuclear factor-kB ligand (RANK-L)/osteoprotegerin (OPG) system have been implicated in several metabolic bone diseases characterized by increased osteoclast differentiation and activation and enhanced bone resorption. Design: We aimed to assess OPG levels and to investigate the possible relation between OPG levels, bone status and glycemic control in a group of prepubertal children with T1DM without microvascular complications. Methods: Twenty-six prepubertal T1DM children (median age 9.9 years, range 4.1 -13.1 years) were studied. In all patients, serum OPG, hemoglobin (Hb)A1c, parathyroid hormone (PTH) and 25-dihydroxyvitamin D (25-D) levels were evaluated. Bone quality was determined by measuring the attenuation of ultrasound waves by bone (broadband ultrasound attenuation (BUA)) at the calcaneal site. The data were compared with those of a group of 45 age-, sex-and body-size-matched healthy children. Results: Children with T1DM showed a reduced Z-score BUA in comparison with the control group (Student's t-test, P , 0.0001). Plasma OPG levels were significantly higher in diabetic children than in controls (Student's t-test, P , 0.0001). In T1DM children, Z-score BUA values displayed a significant correlation with OPG (Student's t-test, r ¼ 2 0.62; P ¼ 0.001), and HbA1c (r ¼ 20.59; P ¼ 0.007). OPG levels were significantly correlated with HbA1c (r ¼ 0.56; P ¼ 0.008). In a multiple regression analysis including age, duration of diabetes, physical activity, calcium intake, mean HbA1c and Z-score BUA, only HbA1c significantly predicted serum OPG levels (beta 0.67; P ¼ 0.003). Conclusions: Prepubertal children with T1DM have a significant increase of OPG levels. OPG serum concentrations are correlated to calcaneal BUA and HbA1c values. OPG could be a new marker of reduced bone mass in children with T1DM.European Journal of Endocrinology 153 879-885

Objective-Microvascular endothelium is one of the main targets of the inflammatory response. On specific activation, endothelial cells recruit Th1-lymphocytes at the inflammatory site. We investigated the intracellular signaling mediating tumor necrosis factor (TNF)-␣ and interferon (IFN)-␥ inflammatory response in human microvascular endothelial cells (HMEC-1) and the interfering effects of the peroxisome-proliferator-activated-receptor (PPAR␥) agonist, rosiglitazone (RGZ). Methods and Results-TNF␣ and IFN␥, mainly when combined, stimulate IFN␥-inducible protein of 10 kDa (IP10) and fractalkine production evaluated by ELISA and TaqMan analyses. This effect is not only mediated by activation of the NFkB and Stat1 classic pathways, but also involves a rapid increase in phosphorylation and activation of extracellular signal-regulated kinases (ERK1/2) as measured by Western blot. RGZ interferes with TNF␣ and IFN␥ stimulation of IP10, fractalkine, and adhesion molecule through a novel rapid mechanism which involves the blocking of ERK activation. Key Words: thiazolidinediones Ⅲ MAPK Ⅲ CXCL10 Ⅲ endothelium Ⅲ Th1-response T umor necrosis factor (TNF)-␣ and interferon (IFN)-␥ are the pivotal cytokines coordinating interactions between infiltrating lymphocytes/macrophages and resident cells during the vascular inflammatory Th1-response. Th1-oriented immune responses are implicated in several systemic pathologies such as autoimmune diseases, atherogenesis, type 2 diabetes (T2D), and they also play a major role in the development of acute and chronic rejection as well as in chronic allograft nephropathy. 1 IFN␥, primarily secreted by activated T-lymphocytes, represents the cardinal Th1-cytokine whereas TNF␣, secreted by monocytes, macrophages, and resident cells, is considered a pleiotropic cytokine involved in a general inflammatory response. Both cytokines modulate the expression of cellular adhesion molecules (CAM) in endothelial cells (ECs). A synergistic action of TNF␣ and IFN␥ in promoting inflammatory response through chemokine secretion has been described. 2 In particular, IFN␥ induces ECs to secret CXC chemokines, such as fractalkine, IFN␥-inducible T-cell ␣-chemoattractant, monokine-induced by IFN␥ and IFN␥-inducible protein of 10 kDa (IP10). Both IP10 and fractalkine chemoattractant activity is directed toward Th1-lymphocytes. 1,3 Thiazolidinediones (TZD) are a pharmacological class of drugs currently used in T2D to improve glucose homeostasis by increasing insulin sensitivity. Besides their well established effects on lipid metabolism and glucose homeostasis, a novel role of TZD in regulating the inflammatory response 4 through a direct action on cells of natural and induced immunity is recently emerging, both in vitro and in animal models of human inflammatory disorders. 5,6 Experimental evidence suggests that the TZD receptor, PPAR␥, interferes with cytokine-induced chemokine secretion in monocytes, 7 macrophages, 8 and venous endothelial cells. 9 TZD action seems to be mainly attributable to their ability ...

Rosiglitazone (RGZ), a thiazolidinedione ligand of the peroxisome proliferator-activated receptor (PPAR)-γ, has been recently described as possessing antitumoral properties. We investigated RGZ effect on cell proliferation in two cell line models (SW13 and H295R) of human adrenocortical carcinoma (ACC) and its interaction with the signaling pathways of the activated IGF-I receptor (IGF-IR). We demonstrate a high expression of IGF-IR in the two cell lines and in ACC. Cell proliferation is stimulated by IGF-I in a dose- and time-dependent manner and is inhibited by RGZ. The analysis of the main intracellular signaling pathways downstream of the activated IGF-IR, phosphatidyl inositol 3-kinase (PI3K)-Akt, and extracellular signal-regulated kinase (ERK1/2) cascades reveals that RGZ rapidly interferes with the Akt and ERK1/2 phosphorylation/activation which mediates IGF-I stimulated proliferation. In conclusion, our results suggest that RGZ exerts an inhibitory effect on human ACC cell proliferation by interfering with the PI3K/Akt and ERK1/2 signaling pathways downstream of the activated IGF-IR.

Articular cartilage defects, an exceedingly common problem closely correlated with advancing age, is characterized by lack of spontaneous resolution because of the limited regenerative capacity of adult articular chondrocytes. Medical and surgical therapies yield unsatisfactory short-lasting results. Recently, cultured autologous chondrocytes have been proposed as a source to promote repair of deep cartilage defects. Despite encouraging preliminary results, this approach is not yet routinely applicable in clinical practice, but for young patients. One critical points is the isolation and ex vivo expansion of large enough number of differentiated articular chondrocytes. In general, human articular chondrocytes grown in monolayer cultures tend to undergo dedifferentiation. This reversible process produces morphological changes by which cells acquire fibroblast-like features, loosing typical functional characteristics, such as the ability to synthesize type II collagen. The aim of this study was to isolate human articular chondrocytes from elderly patients and to carefully characterize their morphological, proliferative, and differentiative features. Cells were morphologically analyzed by optic and transmission electron microscopy (TEM). Production of periodic acid-schiff (PAS)-positive cellular products and of type II collagen mRNA was monitored at different cellular passages. Typical chondrocytic characteristics were also studied in a suspension culture system with cells encapsulated in alginate-polylysine-alginate (APA) membranes. Results showed that human articular chondrocytes can be expanded in monolayers for several passages, and then microencapsulated, retaining their morphological and functional characteristics. The results obtained could contribute to optimize expansion and redifferentiation sequences for applying cartilage tissue engineering in the elderly patients.