Jean-Paul Thissen

Inhibition by interleukin-1 beta and tumor necrosis factor-alpha of the insulin-like growth factor I messenger ribonucleic acid response to growth hormone in rat hepatocyte primary culture.

The cytokines are the putative mediators of the catabolic reaction that accompanies infection and trauma. Evidence suggests that their catabolic actions are indirect and potentially mediated through changes in hormonal axis such as the hypothalamo-pituitary-adrenal axis. Insulin-like growth factor I (IGF-I) is a GH-dependent growth factor that regulates the protein metabolism. To determine whether cytokines can directly inhibit the production of IGF-I by the liver, we investigated the regulation of IGF-I gene expression by interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha (10 ng/ml) in a model of rat primary cultured hepatocytes. Hepatocytes were isolated by liver collagenase perfusion and cultured on Matrigel 48 h before experiments. Each experiment was performed in at least three different animals. In the absence of GH, IL-1 beta and TNF-alpha did not affect the IGF-I messenger RNA (mRNA) basal levels, whereas IL-6 increased it by a factor of 2.5 after 24 h (P < 0.05). GH (500 ng/ml) alone stimulated the IGF-I gene expression markedly (5-to 10-fold increase) after 24 h (P < 0.001). IL-1 beta, and TNF-alpha to a lesser extent, dramatically inhibited the IGF-I mRNA response to GH (IL-1 beta: -82%, P < 0.001 and TNF-alpha: -47%, P < 0.01). The half-maximal inhibition of the IGF-I mRNA response to GH was observed for a concentration of IL-1 beta between 0.1 and 1 ng/ml. Moreover, IL-1 beta abolished the IL-6-induced IGF-I mRNA response. In contrast, IL-6 did not impair the IGF-I mRNA response to GH. To determine the potential role of the GH receptor (GHR) and the GH-binding protein (GHBP) in this GH resistance, we assessed the GHR and GHBP mRNAs response to these cytokines. GH alone did not affect the GHR/GHBP mRNA levels. IL-1 beta markedly decreased the GHR and GHBP mRNA levels (respectively, -68% and -60%, P < 0.05). Neither TNF-alpha nor IL-6 affected the GHR/GHBP gene expression. In conclusion, our results show that IL-1 beta, and TNF-alpha to a lesser extent, blunt the IGF-I mRNA response to GH. The resistance to GH induced by IL-1 beta might be mediated by a decrease of GH receptors, as suggested by the marked reduction of GHR mRNA. These findings suggest that decreased circulating IGF-I, in response to infection and trauma, may be caused by a direct effect of cytokines at the hepatocyte level.

GH insensitivity induced by endotoxin injection is associated with decreased liver GH receptors.

Sepsis induces a state of growth hormone (GH) resistance associated with a decrease of circulating insulin-like growth factor (IGF) I, a GH-dependent anabolic hormone mainly produced by the liver. To address the mechanisms that might trigger GH insensitivity in sepsis, we investigated the regulation of liver GH receptor (GHR) and its gene expression by endotoxin. Endotoxin injection in rats decreased serum IGF-I and liver GH-binding sites after 10 h. In contrast to liver GHR, circulating GH-binding protein (GHBP) levels were not significantly reduced after endotoxin injection. The parallel decrease in IGF-I and GHR and in their corresponding liver mRNAs suggests that decreased serum IGF-I and liver GHR were likely to result from decreased liver synthesis. Although GH administration in control animals significantly enhanced serum IGF-I, it did fail to prevent the decline in serum IGF-I and liver GH-binding sites in endotoxemic rats. In this study, we showed that endotoxin injection induces a state of GH insensitivity associated with decreased liver GHR. This decline in GHR, which cannot be prevented by exogenous GH, might contribute to the GH insensitivity observed in sepsis.Sepsis induces a state of growth hormone (GH) resistance associated with a decrease of circulating insulin-like growth factor (IGF) I, a GH-dependent anabolic hormone mainly produced by the liver. To address the mechanisms that might trigger GH insensitivity in sepsis, we investigated the regulation of liver GH receptor (GHR) and its gene expression by endotoxin. Endotoxin injection in rats decreased serum IGF-I and liver GH-binding sites after 10 h. In contrast to liver GHR, circulating GH-binding protein (GHBP) levels were not significantly reduced after endotoxin injection. The parallel decrease in IGF-I and GHR and in their corresponding liver mRNAs suggests that decreased serum IGF-I and liver GHR were likely to result from decreased liver synthesis. Although GH administration in control animals significantly enhanced serum IGF-I, it did fail to prevent the decline in serum IGF-I and liver GH-binding sites in endotoxemic rats. In this study, we showed that endotoxin injection induces a state of GH insensitivity associated with decreased liver GHR. This decline in GHR, which cannot be prevented by exogenous GH, might contribute to the GH insensitivity observed in sepsis.

Hematological changes in anorexia nervosa are correlated with total body fat mass depletion.

OBJECTIVEnTo assess the relationships between total body fat mass (FM) and hematological abnormalities in anorexia nervosa (AN).nnnMETHODnPeripheral blood parameters and body composition were determined in 10 anorectic patients and 19 age- and sex-matched healthy subjects. In patients with AN, magnetic resonance imaging (MRI) studies of bone marrow were also performed.nnnRESULTSnCompared with controls, patients with AN had -41% body weight, -81% FM, -18.8% lean tissue mass (LTM), and -22.6% bone mineral content; they also had lower mean total leukocyte (4.52 +/- 0.47 vs. 6.28 +/- 0.33 x 10(3)/microliter, p < .005), neutrophil (2.45 +/- 0.34 vs. 3.46 +/- 0.20 x 10(3)/microliter, p < .005), monocyte (0.24 +/- 0.03 vs. 0.37 +/- 0.03 x 10(3)/microliter, p < .05), and platelet counts (184 +/- 17 vs. 238 +/- 9 x 10(3)/microliter, p < .005). Hemoglobin level was normal and comparable in both groups. In patients with AN, but not in controls, total leukocyte, neutrophil, eosinophil, and monocyte counts as well as hemoglobin level were highly correlated with FM expressed in absolute values or in percentage of body weight, but not with LTM. Moreover, AN patients with signal intensity patterns suggestive of serous atrophy of bone marrow at MRI had not only lower erythrocyte, leukocyte, neutrophil, and platelet counts, but they also had lower FM than AN patients with normal MRI patterns.nnnDISCUSSIONnHematological changes in AN, as assessed by peripheral blood parameters and MRI patterns of bone marrow, are correlated with total body FM depletion, suggesting that the reduction of adipose tissue adversely affects hematopoiesis.

Decreased acid-labile subunit (ALS) levels by endotoxin in vivo and by interleukin-1beta in vitro.

The production by the liver of the three subunits of the growth hormone (GH)-dependent 150 kDa complex (IGF-I, IGF-binding protein-3 and acid-labile subunit or ALS) is primarily under the control of GH. Recent data have shown that, besides GH, endotoxin (LPS) and cytokines may regulate the liver IGF-I gene. To investigate the potential regulation of ALS by LPS, we measured serum ALS by immunoblot, 5 and 10 h after IP injection of LPS (250 or 750 microg/100 g BW vs saline), in 4-week-old female Wistar rats (four per group). Ten hours after injection, serum ALS levels were reduced by 57% (delta%) with the lower dose (P<0.05) and by 81% with the higher dose (P<0.01) by comparison with saline-treated rats. The decrease in ALS levels in response to LPS was not prevented by exogenous GH. To investigate the role of interleukin (IL)-1beta in the regulation of ALS, primary cultured rat hepatocytes were exposed to increasing concentrations of IL-1beta. Cell exposure to IL-1beta markedly decreased both basal and GH-stimulated ALS levels (-70%; P<0.01) in a dose-dependent fashion, with the half-maximal inhibitory effect at concentrations of 0.1 ng/ml. Our results show that endotoxin induces a rapid decline in circulating ALS that is potentially mediated through IL-1beta. By limiting the formation of the 150 kDa complex, this reduction in circulating ALS might contribute to the rapid decline in serum IGF-I observed in sepsis.

Zinc regulation of insulin-like growth factor-I (IGF-I), growth hormone receptor (GHR) and binding protein (GHBP) gene expression in rat cultured hepatocytes.

Dietary zinc depletion in vivo attenuates growth, decreases circulating insulin-like growth factor-I (IGF-I) and liver growth hormone (GH) receptors (GHR). In order to investigate a direct role of zinc in the regulation of IGF-I, GHR and GH binding protein (GHBP) gene expression, we evaluated the response of their mRNAs to changes in zinc availability in primary culture of rat hepatocytes. Exposition of cells to the zinc chelator DTPA (diethylenetriaminepenta-acetic acid) did not decrease IGF-I and GHBP mRNAs while it strongly inhibited metallothionein (MT) gene expression. On the other hand, zinc excess (50 vs. 1.5 microM) decreased IGF-I, GHR and GHBP mRNAs while it stimulated MT mRNA. However, the response of IGF-I to GH was not affected by the exposure to DTPA nor zinc excess. Furthermore, zinc repletion of primary cultured hepatocytes isolated from zinc-deprived rats did not increase IGF-I nor GHR/GHBP mRNAs. Therefore, our results suggest that the IGF-I decline induced in vivo by zinc deficiency is not caused by reduced extracellular zinc availability at the hepatocyte level. Although IGF-I and MT gene expression is down-regulated by dietary zinc depletion, underlying mechanisms of regulation are different for both genes.

Continuous administration of growth hormone does not prevent the decrease of IGF-I gene expression in zinc-deprived rats despite normalization of liver GH binding.

To determine the role of reduced liver GH binding (GHR) in the decreased IGF-I observed in zinc-deficient (ZD) animals, we investigated the effects of GHR restoration on growth, insulin-like growth factor I (IGF-I) and its binding proteins (IGFBPs) in ZD rats. Rats were fed for 4 weeks a zinc-deficient diet (ZD Zn, 0 ppm) or a Zinc-normal diet (pair-fed or PF; Zn, 75 ppm). ZD rats received continuous s.c. infusion of bovine growth hormone (bGH) (100 microg/d) for the 4 weeks or for the last week of the study. Compared with pair-fed rats, zinc deficiency produced attenuated weight gain (-43%, P < 0.001), lower serum IGF-I and liver IGF-I mRNA (-52%, P < 0.001 and -44%, P < 0.05), lower serum IGFBPs (IGFBP-3 -66%, IGFBP-4 -48%, 34-29 kDa IGFBP cluster -53%, P < 0.05), lower liver GHR and its mRNA (-20 and -34%, P < 0.05) and lower serum growth hormone binding protein (GHBP) and its mRNA (-56 and -48%, P < 0.05; all comparisons vs PF rats). Exogenous bGH given continuously normalized the liver GHR, serum GHBP and their liver mRNAs, as well as circulating IGFBPs. Despite restoration of GHR and GHBP to normal, growth, serum IGF-I and its liver mRNA were not stimulated by GH infusion in ZD rats, indicating that IGF-I synthesis requires the presence of zinc in addition to GH, and that the lack of growth-promoting action of GH in zinc-deprived rats results from a defect beyond GH binding to its liver receptors.

Effect of high concentrations of glucose on differentiation of rat trophoblast cells in vitro

Aims/hypothesisPrevious studies have shown that diabetic placentas are characterized by structural and biochemical anomalies, including defects in the differentiation of trophoblasts. In this study, the Rcho-1 cell line was used to investigate the impact of high glucose concentrations on different markers of differentiation of rat trophoblast cells in giant cells (endoreduplication, invasive phenotype and endocrine phenotype).MaterialsRcho-1 cells were incubated for 12 days in medium supplemented with different concentrations of glucose and 10% horse serum to optimize differentiation. The cells were examined for the proportion of nuclei showing signs of apoptosis. The effect of high glucose was investigated on the endoreduplication process, on invasive phenotype (secretion of gelatinase B) and on endocrine phenotype (expression of placental lactogen I (PL-I) and II (PL-II) and progesterone secretion).ResultsApoptosis was not induced by high glucose in Rcho-1. The number of cells was higher in the cultures exposed to high glucose (p<0.05) and their nuclei contained more DNA compared with control cells (p<0.001), while their nuclear size was smaller (p<0.001). Gelatinase B secretion increased during differentiation but no difference was found when gelatinase B secretion from trophoblasts exposed to high glucose was compared with the control cells. Rcho-1 cell cultures showed an increase in PL-I and PL-II mRNA expressions during differentiation and which was not affected by high glucose. Progesterone secretion increased during differentiation in control cultures. However, this increase was abolished when trophoblasts were cultured in high glucose.Conclusions/interpretationOur data suggest that high glucose influences the endoreduplication process and the steroidogenesis during differentiation of rattrophoblasts.

Regulation of Insulin-like Growth Factor-I by Nutrition

Nutrition is one of the principal regulators of circulating IGF-I. Many mechanisms are involved in the nutritional regulation of IGF-I. n n nBoth energy and protein are critical to the regulation of serum IGF-I concentrations. After fasting, adequate energy and protein are necessary for restoration of serum IGF-I, but energy may be somewhat more important than protein. While a low intake of protein is able to increase IGF-I in the presence of adequate energy, there is a threshold requirement of energy below which optimal protein intake fails to raise IGF-I after fasting. n n nThe decline of serum IGF-I during dietary restriction is independent of diet-induced alterations in pituitary GH secretion. In severe dietary restriction (fasting), a marked decrease in the number of liver somatogenic receptors suggests that a GH receptor defect is involved in the decline of serum IGF-I. In protein restriction, the decline of serum IGF-I results from a postreceptor defect in GH action at the hepatic level. n n nNutritional deprivation decreases hepatic IGF-I production by diminishing IGF-I gene expression. Decline in IGF-I gene expression results from both transcriptional and post-transcription mechanisms. n n nDiet restriction also increases the clearance and degradation of serum IGF-I through changes in the levels of circulating IGFBPs. n n nThe molecular mechanisms leading to the decline of IGF-I in catabolic stress seem to be similar to those operational in food deprivation. n n nNutrients may also control the biological action of IGF-I, either directly or indirectly, through changes in IGFBPs.

D-lactic acidosis: an unusual cause of encephalopathy in a patient with short bowel syndrome

Abstract A 24-year-old woman with a short bowel syndrome following post-ischemic small bowel resection, developed several episodes of lethargy, echolalia and ataxia. D-lactic acidosis was identified as the cause of neurological disturbances. This infrequent disorder can be precipitated by intake of a large amount of sugars, in patients with short bowel syndrome. It should be suspected in the presence of metabolic acidosis with increased anion gap and a normal level of L-lactic acid. The diagnosis relies on the specific dosage of D-lactic stereoisomer. Proper management involves rehydration, diet adaptation and oral administration of poorly absorbed antibiotics in order to modify the colonic flora responsible for D-lactic production.

Severe hypophosphatemia in a patient with anorexia nervosa during enteral refeeding.

Abstract Hypophosphatemia is a seldom but potentially fatal complication of the nutritional recovery or refeeding syndrome in patients with protein-calorie malnutrition or starvation. We report here the case of a 35-year-old anorexic patient who presented a severe but uncomplicated hypophosphatemia during enteral refeeding, despite phosphorus supplementation. Serum phosphorus monitoring is recommended in severely malnourished anorexic patients, particularly during the first week of refeeding, be it parenteral or enteral.