Body fat and C-reactive protein levels in healthy non-obese men.

BACKGROUND AND AIM: The relationships between C-reactive protein (CRP) levels, adipose tissue and metabolic alterations have not been clearly established in healthy non-obese subjects. We investigated the relationships between body fat, CRP levels and metabolic variables in healthy, non-obese sons of patients affected by metabolic syndrome (MS). METHODS AND RESULTS: Age, CRP and interleukin 6 (IL-6) levels, anthropometric measures (body mass index, BMI; waist circumference and waist-to-hip ratio, WHR), total and regional fat content (as determined by means of dual X-ray absorptiometry, DXA), total and LDL cholesterol, and the metabolic variables related to MS (HDL-cholesterol, triglyceride, glucose and insulin levels; the fasting insulin resistance index, FIRI; blood pressure) were evaluated in 85 healthy non-obese sons of MS patients. Linear and multiple regression analyses were used to evaluate the relationships between body fat, metabolic variables and CRP levels, and to investigate whether the association between body fat content and metabolic variables persists after adjustment for CRP levels. Body fat was associated with all of the investigated variables. CRP levels were associated with total and regional body fat, the anthropometric index of weight, age, and with some metabolic alterations (HDL-cholesterol and triglyceride levels, systolic blood pressure, and fasting insulin and LDL-cholesterol levels). The associations between total body fat and the metabolic variables did not change after adjustment for CRP levels. Total body fat was the best predictor of CRP levels (p<0.0001). CONCLUSIONS: In healthy, non-obese sons of MS patients, total body fat is the best predictor of CRP levels, and remains closely associated with metabolic abnormalities after adjustment for CRP levels. These findings strongly support the hypothesis that body fat is the main determinant of metabolic abnormalities and a low inflammatory state, at least in healthy subjects.

herg encodes a K+ current highly conserved in tumors of different histogenesis: a selective advantage for cancer cells?

The human ether-a-go-go-related gene (herg) encodes a K+ current (IHERG) that plays a fundamental role in heart excitability by regulating the action potential repolarization (IKr); mutations of this gene are responsible for the chromosome 7-linked long QT syndrome (LQT2). In this report, we show that in a variety (n = 17) of tumor cell lines of different species (human and murine) and distinct histogenesis (neuroblastoma, rhabdomyosarcoma, adenocarcinoma, lung microcytoma, pituitary tumors, insulinoma beta-cells, and monoblastic leukemia), a novel K+ inward-rectifier current (IIR), which is biophysically and pharmacologically similar to IHERG, can be recorded with the patch-clamp technique. Northern blot experiments with a human herg cDNA probe revealed that both in human and murine clones the very high expression of herg transcripts can be quantified in at least three clearly identifiable bands, suggesting an alternative splicing of HERG mRNA. Moreover, we cloned a cDNA encoding for IIR from the SH-SY5Y human neuroblastoma. The sequence of this cDNA result was practically identical to that already reported for herg, indicating a high conservation of this gene in tumors. Consistently, the expression of this clone in Xenopus oocytes showed that the encoded K+ channel had substantially all of the biophysical and pharmacological properties of the native IIR described for tumor cells. In addition, in the tumor clones studied, IIR governs the resting potential, whereas it could not be detected either by the patch clamp or the Northern blot techniques in cells obtained from primary cell cultures of parental tissues (sensory neurons and myotubes), whose resting potential is controlled by the classical K+ anomalous rectifier current. This current substitution had a profound impact on the resting potential, which was markedly depolarized in tumors as compared with normal cells. These results suggest that IIR is normally only expressed during the early stages of cell differentiation frozen by neoplastic transformation, playing an important pathophysiological role in the regulatory mechanisms of neoplastic cell survival. In fact, because of its biophysical features, IIR, besides keeping the resting potential within the depolarized values required for unlimited tumor growth, could also appear suitable to afford a selective advantage in an ischemic environment.

DNA binding activity of the glucocorticoid receptor is sensitive to redox changes in intact cells.

The effect of changes of redox conditions on glucocorticoid receptor (GR) activity in intact cells has been studied using two approaches. One was to evaluate the GR-DNA binding in extracts of COS2 cells transiently overexpressing GR and in which reactive oxygen intermediates (ROI) accumulate as a consequence of glutathione (GSH) depletion. GR-DNA binding was significantly decreased in COS2 cells treated with diethylmaleate (DEM), which causes GSH depletion by forming GSH-DEM complexes. A similar effect was observed for Sp1, another Zn-finger transcription factor, whereas no difference was observed for the C/EBP transcription factor, which is known to be unaffected by redox changes in vitro. N-Acetylcysteine (NAC), which counteracts the effects of DEM by increasing GSH biosynthesis, prevents the decrease of GR-DNA binding in cells treated with DEM. The GR-DNA binding efficiency was similarly decreased using extracts from H2O2-treated COS2 cells and from COS2 cells treated with buthionine sulphoximine, which causes GSH depletion via a mechanism different from that of DEM. The other approach was to evaluate the efficiency of a GR-regulated promoter under different redox conditions. In HeLa cells, transfected with a plasmid containing the CAT gene under the control of the glucocorticoid responsive element (GRE) within the mouse mammary tumor virus promoter, and treated with dexamethasone to activate GR, exposure to DEM significantly impaired the activation of CAT gene expression induced by dexamethasone. Also in this case NAC treatment inhibited the effects of DEM.

Effects of keratinocyte-secreted soluble factors on spreading, number of dendrites and cell-cell contacts of human epidermal melanocytes and dermal fibroblasts: a quantitative analysis.

We previously demonstrated that spreading and clustering of in vitro cultured human keratinocytes are autocrine-induced phenomena, mediated by keratinocyte-secreted soluble factor. In this paper, the effects of this factor on spreading, number of dendrites and cell-cell contacts of the two cellular components of skin, melanocytes and fibroblasts have been studied 24 h after plating cells on uncoated plastic surfaces in MCDB153 serum-free medium or in the same medium conditioned by keratinocytes (KCM). Spreading of melanocytes present in the epidermal cell population remained constant at increasing cell density, while that of keratinocytes showed a statistically significant increase. Moreover, time-course experiments showed that the rate of spreading was faster for melanocytes. At increasing epidermal cell density, a statistically significant increase in number of dendrites and cell-cell contacts of melanocytes was observed. Similar results were obtained when melanocytes were plated both in coculture with keratinocytes (as epidermal cell cultures) or as a pure cell population in keratinocyte conditioned medium (KCM), suggesting that the observed phenomena are due to keratinocyte-secreted soluble factors and not to direct keratinocyte-melanocyte interactions. The addition of nerve growth factor (NGF) to fresh medium or addition of an inactivating anti-NGF monoclonal antibody (alpha D11) to KCM did not affect the number of dendrites or cell-cell contacts of melanocytes. Keratinocyte-secreted soluble factor(s) present in KCM also dramatically influenced morphology and cell-cell contacts of human dermal fibroblasts.

Inhibition of the differentiation of human myeloid cell lines by redox changes induced through glutathione depletion.

We have investigated the effect of redox changes in vivo on the differentiation of two human myeloid cell lines, HL-60 and KG-1. The glutathione-depleting agent diethyl maleate (DEM) prevented the development of differentiated features in response to phorbol esters, including adherence of the cells to plastic surfaces and repression of the myeloperoxidase and CD34 genes. Moreover, DEM abolished phorbol 12-myristate 13-acetate-induced activation of the transcription factors AP-1 and Egr-1, suggesting that inhibition of differentiation may be due, at least in part, to redox modifications of these proteins.