Safety and Tolerability of Targeted Medical Nutrition for Cachexia in Non-Small-Cell Lung Cancer: A Randomized, Double-Blind, Controlled Pilot Trial.

Background: This pilot, double-blind, comparator-controlled trial evaluated the safety and tolerability of an oral targeted medical nutrition (TMN) supplement for the management of cachexia in patients with non-small-cell lung cancer (NSCLC).Methods: Patients receiving first-line chemotherapy for NSCLC with weight loss or low BMI were randomized 1:1 to receive juice-based TMN (∼200 kcal; 10 g whey protein; ≥2.0 g eicosapentaenoic acid/docosahexaenoic acid in fish oil; and 10 µg 25-hydroxy-vitamin D3) or a milk-based isocaloric comparator twice daily for 12 weeks (ClinicalTrials.gov: NCT02515032). Primary endpoints included number/type of adverse events and changes in vital signs/laboratory parameters. Secondary endpoints included measures of clinical relevance. Survival was an exploratory endpoint.Results: The TMN group (n = 26; mean 64.4 years) experienced fewer adverse events (64 vs. 87) than the comparator group (n = 29; mean 66.0 years), including fewer cases of neutropenia (0 vs. 4). Compliance was slightly lower in the TMN (58.5%) vs. comparator group (73.6%). There were no statistically significant between-group differences in efficacy endpoints. Fewer (4 vs. 10) patients who received TMN than comparator had died by 1-year post baseline.Conclusions: TMN was well tolerated. Trends for improved clinical outcomes with TMN identified in this study warrant further investigation.

Targeted medical nutrition for cachexia in chronic obstructive pulmonary disease: a randomized, controlled trial.

BACKGROUND: Cachectic patients with chronic obstructive pulmonary disease (COPD) may benefit from nutritional support. This double-blind, randomized, controlled trial evaluated the safety and efficacy of targeted medical nutrition (TMN) vs. an isocaloric comparator in pre-cachectic and cachectic patients with COPD. METHODS: Patients aged ≥50 years with moderate-to-severe COPD and involuntary weight loss or low body mass index (16-18 kg/m2 ) were randomized 1:1 to receive TMN (~230 kcal; 2 g omega-3 fatty acids; 10 µg 25-hydroxy-vitamin D3) or isocaloric comparator twice daily for 12 weeks (ClinicalTrials.gov Identifier: NCT02442908). Primary safety endpoints comprised adverse events and changes in vital signs, laboratory parameters, and concomitant medications. Secondary efficacy endpoints included changes in weight, body composition, exercise tolerance, metabolic biomarkers, and systemic inflammation. RESULTS: Forty-five patients were randomized to receive TMN (n = 22; mean 69.2 years) or isocaloric comparator (n = 23; mean 69.7 years). TMN was well tolerated. Adverse events were similar in number and type in both groups. Compliance to both products was good (TMN, 79%; comparator, 77%). Both groups gained weight, but the TMN group gained comparatively more fat mass (P = 0.0013). Reductions in systolic blood pressure (P = 0.0418) and secondary endpoints of triglycerides (P = 0.0217) and exercise-induced fatigue (P = 0.0223) and dyspnoea (P = 0.0382), and increases in high-density lipoprotein cholesterol (P = 0.0254), were observed in the TMN vs. the comparator group by week 12. CONCLUSIONS: Targeted medical nutrition containing high-dose omega-3 fatty acids, vitamin D, and high-quality protein is well tolerated with a good safety profile and has positive effects on blood pressure and blood lipids and on exercise-induced fatigue and dyspnoea. Therefore, this TMN could be clinically beneficial in the nutritional and metabolic support of pre-cachectic and cachectic patients with COPD.

Patient-reported adverse effects of high-dose intravenous methylprednisolone treatment: a prospective web-based multi-center study in multiple sclerosis patients with a relapse.

In a prospective multi-center observational study, we evaluated the frequency, severity, and impact on activities of daily living (ADL) of adverse effects (AEs) of high-dose intravenous methylprednisolone (IVMP) in relapsing remitting multiple sclerosis (MS) patients with a relapse. Online self-report questionnaires stating IVMP's most common AEs were completed at baseline, the 2nd day of treatment, and 1 day and 1 week after treatment. Eighty-five patients were included, 66 completed the baseline questionnaire, and 59 completed at least one post-baseline questionnaire. Patients reported on average 4 (median) AEs; two (3.4 %) reported no AE. Most frequent was change in taste (61 %), facial flushing (61 %), sick/stomach pain (53 %), sleep disturbance (44 %), appetite change (37 %), agitation (36 %), and behavioral changes (36 %). Of all AEs, 34.3 % were severe and 37.9 % impacted on ADL. A 3-day course resulted in 4 (median) AEs and a 5-day course in 7. All patients with high disease impact had two or more AEs, compared with 79 % of those with low impact (p < 0.01). Of patients with high disability, 45 % had severe AEs, compared with 16 % of those with low disability. Severe central nervous system (CNS)-related AEs occurred two times more frequently in patients with high disease impact, and two-and-a-half times more frequently in patients with high disability. Therefore, in virtually all patients, high-dose IVMP leads to AEs, with about one of three AEs being severe with impact on ADL. Patients with high disease impact or high disability may experience more (severe) AEs, due to a higher occurrence of severe CNS-related AEs.

Glucocorticoid-mediated effects on metabolism are reversed by targeting 11 beta hydroxysteroid dehydrogenase type 1 in human skeletal muscle.

BACKGROUND: Adipose tissue and liver play important roles in mediating the metabolic actions of glucocorticoids. However, the effects of glucocorticoids on glucose and lipid metabolism in skeletal muscle are not understood completely. Intracellular glucocorticoid action is dependent on 11 beta-hydroxysteroid dehydrogenase 1 (HSD1), an enzyme that converts cortisone to active cortisol. METHODS: We investigated the direct role of HSD1 in cultured primary human skeletal muscle cells using siRNA and pharmacological inhibitors of the enzyme. Primary human skeletal muscle cells were cultured in the presence of 0.5 microM cortisone or 0.5 microM cortisol for eight days. siRNA was utilized to reduce expression of either HSD1 or pyruvate dehydrogenase kinase (PDK) 4. Effects of pharmacological inhibitors of HSD1 were also studied. RESULTS: Exposure to cortisone or cortisol decreased basal glucose uptake and glucose incorporation into glycogen, but was without effect on the insulin-stimulated response. Glucocorticoid exposure increased palmitate oxidation, as well as the expression of PDK4. siRNA-mediated reduction or pharmacological inhibition of HSD1 prevented the effects of cortisone, but not cortisol, on metabolic responses. siRNA-mediated reduction of PDK4 prevented the effect of cortisol to attenuate glycogen synthesis. CONCLUSION: Targeted reduction or pharmacological inhibition of HSD1 in primary human skeletal muscle cells prevents the effects of cortisone, but not cortisol, on glucose metabolism and palmitate oxidation. Furthermore, the glucocorticoid-mediated reductions in glucose metabolism are dependent on PDK4.

Signaling specificity of interleukin-6 action on glucose and lipid metabolism in skeletal muscle.

We identified signaling pathways by which IL-6 regulates skeletal muscle differentiation and metabolism. Primary human skeletal muscle cells were exposed to IL-6 (25 ng/ml either acutely or for several days), and small interfering RNA gene silencing was applied to measure glucose and fat metabolism. Chronic IL-6 exposure increased myotube fusion and formation and the mRNA expression of glucose transporter 4, peroxisome proliferator activated receptor (PPAR)alpha, PPARdelta, PPARgamma, PPARgamma coactivator 1, glycogen synthase, myocyte enhancer factor 2D, uncoupling protein 2, fatty acid transporter 4, and IL-6 (P < 0.05), whereas glucose transporter 1, CCAAT/enhancer-binding protein-alpha, and uncoupling protein 3 were decreased. IL-6 increased glucose incorporation into glycogen, glucose uptake, lactate production, and fatty acid uptake and oxidation, concomitant with increased phosphorylation of AMP-activated protein kinase (AMPK), signal transducer and activator of transcription 3, and ERK1/2. IL-6 also increased phosphatidylinositol (PI) 3-kinase activity (450%; P < 0.05), which was blunted by subsequent insulin-stimulation (P < 0.05). IL-6-mediated glucose metabolism was suppressed, but lipid metabolism was unaltered, by inhibition of PI3-kinase with LY294002. The small interfering RNA-directed depletion of AMPK reduced IL-6-mediated fatty acid oxidation and palmitate uptake but did not reduce glycogen synthesis. In summary, IL-6 increases glycogen synthesis via a PI3-kinase-dependent mechanism and enhances lipid oxidation via an AMPK-dependent mechanism in skeletal muscle. Thus, IL-6 directly promotes skeletal muscle differentiation and regulates muscle substrate utilization, promoting glycogen storage and lipid oxidation.

Effect of rosiglitazone on early-morning plasma cortisol levels.

OBJECTIVES: PPAR-gamma agonists are able to inhibit pituitary tumour development and tumoral hormonal secretion in rodents both in vitro and in vivo. Their use for treatment of Cushing Disease (CD) has been suggested but the clinical experience with the two PPAR-gamma agonists commercially available (rosiglitazone and pioglitazone) was not impressive. Short-time treatment has been proposed to be the cause of unsuccessful results on CD in humans. We report here the effect on early-morning plasma cortisol levels of a long-time treatment with rosiglitazone at the highest approved dose. METHODS: Because PPAR-gamma receptors are located in normal corticotroph cells we tested in a placebo-controlled study the influence of rosiglitazone on cortisol secretion. The study enrolled 30 newly diagnosed type 2 patients which were assigned to receive either rosiglitazone (8 mg/day) or placebo. Plasma morning cortisol (8.00 a.m.) was measured at the baseline and at the end of the study. RESULTS: Rosiglitazone vs placebo did not modify the early morning plasma levels of cortisol (13 microg/dl [3-21] vs 11 microg/dl [7-23] [median and range]) after 26 weeks of treatment. CONCLUSION: The discrepancy between in vitro and animal data on one side and clinical data on the other side warrant further investigations into the mechanisms of action of PPAR-gamma agonists on ACTH secretion before other clinical studies will be conducted.

Rosiglitazone treatment increases subcutaneous adipose tissue glucose uptake in parallel with perfusion in patients with type 2 diabetes: a double-blind, randomized study with metformin.

CONTEXT: We have shown that rosiglitazone increases whole-body and adipose tissue insulin sensitivity in humans. OBJECTIVE: The aim of this study was to further examine whether possible changes in adipose perfusion could explain increased adipose tissue glucose uptake (GU). PATIENTS: Thirty-seven patients with newly diagnosed type 2 diabetes were included. INTERVENTION: Patients were randomized into treatment with rosiglitazone, metformin, or placebo for 26 wk in a double-blinded trial. DESIGN: Femoral adipose flow and GU were measured with [15O]H2O, [18F]fluorodeoxyglucose and positron emission tomography during euglycemic hyperinsulinemia. Adipose masses were measured using magnetic resonance imaging. RESULTS: Metformin and rosiglitazone treatment improved glycemic control, but only rosiglitazone increased whole-body insulin sensitivity. Rosiglitazone treatment increased flow by 72% (P < 0.01) and GU by 23% (P < 0.05) and thereby decreased adipose tissue glucose extraction by 18% (P < 0.05); no changes were observed in the metformin or placebo-treated groups. When the adipose masses were taken into account, rosiglitazone treatment increased flow by 73% (P < 0.01) and GU by 24% (P < 0.05). During hyperinsulinemia, flow correlated with GU (r = 0.63; P < 0.01). CONCLUSIONS: In conclusion, s.c. GU is associated with flow in patients with type 2 diabetes. Rosiglitazone treatment enhances GU and flow but decreases glucose extraction, suggesting that perfusion may contribute to adipose tissue insulin sensitization by rosiglitazone.

Increased fat mass compensates for insulin resistance in abdominal obesity and type 2 diabetes: a positron-emitting tomography study.

To evaluate the relative impact of abdominal obesity and newly diagnosed type 2 diabetes on insulin action in skeletal muscle and fat tissue, we studied 61 men with (n = 31) or without (n = 30) diabetes, subgrouped into abdominally obese or nonobese according to the waist circumference. Adipose tissue depots were quantified by magnetic resonance imaging, and regional glucose uptake was measured using 2-[(18)F]fluoro-2-deoxyglucose/positron emission tomography during euglycemic hyperinsulinemia. Across groups, glucose uptake per unit tissue weight was higher in visceral (20.5 +/- 1.4 micromol . min(-1) . kg(-1)) than in abdominal (9.8 +/- 0.9 micromol min(-1) . kg(-1), P < 0.001) or femoral (12.3 +/- 0.6 micromol . min(-1) . kg(-1), P < 0.001) subcutaneous tissue and approximately 40% lower than in skeletal muscle (33.1 +/- 2.5 micromol . min(-1) . kg(-1), P < 0.0001). Abdominal obesity was associated with a marked reduction in glucose uptake per unit tissue weight in all fat depots and in skeletal muscle (P < 0.001 for all regions). Recent type 2 diabetes per se had little additional effect. In both intra-abdominal adipose (r = -0.73, P < 0.0001) and skeletal muscle (r = -0.53, P < 0.0001) tissue, glucose uptake was reciprocally related to intra-abdominal fat mass in a curvilinear fashion. When regional glucose uptake was multiplied by tissue mass, total glucose uptake per fat depot was similar irrespective of abdominal obesity or type 2 diabetes, and its contribution to whole-body glucose uptake increased by approximately 40% in obese nondiabetic and nonobese diabetic men and was doubled in obese diabetic subjects. We conclude that 1) in abdominal obesity, insulin-stimulated glucose uptake rate is markedly reduced in skeletal muscle and in all fat depots; 2) in target tissues, this reduction is reciprocally (and nonlinearly) related to the amount of intra-abdominal fat; 3) mild, recent diabetes adds little insulin resistance to that caused by abdominal obesity; and 4) despite fat insulin resistance, an expanded fat mass (especially subcutaneous) provides a sink for glucose, resulting in a compensatory attenuation of insulin resistance at the whole-body level in men.

Effects of metformin and rosiglitazone treatment on insulin signaling and glucose uptake in patients with newly diagnosed type 2 diabetes: a randomized controlled study.

The effect of metformin or rosiglitazone monotherapy versus placebo on insulin signaling and gene expression in skeletal muscle of patients with newly diagnosed type 2 diabetes was determined. A euglycemic-hyperinsulinemic clamp, combined with skeletal muscle biopsies and glucose uptake measurements over rested and exercised muscle, was performed before and after 26 weeks of metformin (n = 9), rosiglitazone (n = 10), or placebo (n = 11) treatment. Insulin-mediated whole-body and leg muscle glucose uptake was enhanced 36 and 32%, respectively, after rosiglitazone (P < 0.01) but not after metformin or placebo treatment. Insulin increased insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation, IRS-1-associated phosphatidylinositol (PI) 3-kinase activity, and phosphorylation of Akt Ser473 and AS160, a newly described Akt substrate that plays a role in GLUT4 exocytosis, approximately 2.3 fold before treatment. These insulin signaling parameters were unaltered after metformin, rosiglitazone, or placebo treatment. Expression of selected genes involved in glucose and fatty acid metabolism in skeletal muscle was unchanged between the treatment groups. Low-intensity acute exercise increased insulin-mediated glucose uptake but was without effect on insulin signaling. In conclusion, the insulin-sensitizing effects of rosiglitazone are independent of enhanced signaling of IRS-1/PI 3-kinase/Akt/AS160 in patients with newly diagnosed type 2 diabetes.

Reduced gene expression of adiponectin in fat tissue from patients with end-stage renal disease.

BACKGROUND: Cardiovascular disease (CVD) is the main cause of death in end-stage renal disease (ESRD) patients. It has been suggested that inflammation plays a key role in the development of both atherosclerosis and malnutrition (MIA), a combination of complications associated with poor outcome. Although plasma levels of adiponectin, a recently discovered anti-inflammatory and antiatherogenic adipocytokine, are markedly elevated in ESRD, gene expression of adiponectin (ApM1) has not been analyzed in ESRD patients. METHODS: We analyzed the ApM1 gene expression in adipose tissue from 18 ESRD patients of whom 9 (7 males, 60 +/- 8 years, BMI 24 +/- 6 kg/m(2)) had a high prevalence of MIA complications, and 9 age- (55 +/- 9 years), gender- (7 males) and BMI- (24 +/- 2 kg/m(2)) matched ESRD patients had few MIA complications. The results were compared with age- (59 +/- 11 years), gender- (7 males), and BMI- (24 +/- 6 kg/m(2)) matched healthy control patients. Information on CVD was obtained at the recruitment based on a detailed medical history. Malnutrition was defined as a subjective global assessment (SGA) score >1. Inflammation was defined as CRP >/=10 mg/L. Gene expression analysis was performed using the in situ hybridization technique. RESULTS: Gene expression of ApM1 was lower in ESRD patients compared with healthy control patients (P= 0.001). On the other hand, when comparing the gene expression between ESRD patients with and without MIA complications, respectively, no difference in the ApM1 gene expression was detected. CONCLUSION: Adiponectin gene expression is significantly down-regulated in ESRD patients compared with healthy control patients. We propose that the decrease in expression may be the result of a negative feedback regulation, as a result of elevated levels of circulating adiponectin caused by renal failure.

Effects of metformin and rosiglitazone monotherapy on insulin-mediated hepatic glucose uptake and their relation to visceral fat in type 2 diabetes.

OBJECTIVE: Impaired insulin-mediated hepatic glucose uptake (HGU) has been implicated in the hyperglycemia of type 2 diabetes. We examined the effects of metformin (2 g/day) and rosiglitazone (8 mg/day) monotherapy on HGU and its relation to subcutaneous fat, visceral fat (VF), and whole-body insulin-mediated glucose metabolism in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Glucose uptake was measured before and after 26 weeks of treatment using positron emission tomography with [(18)F]2-fluoro-2-deoxyglucose during euglycemic hyperinsulinemia; fat depots were quantified by magnetic resonance imaging. RESULTS: Fasting plasma glucose levels were significantly decreased after either rosiglitazone (-0.9 +/- 0.5 mmol/l) or metformin treatment (-1.1 +/- 0.5 mmol/l) in comparison with placebo; only metformin was associated with weight loss (P < 0.02 vs. placebo). When controlling for the latter, the placebo-subtracted change in whole-body glucose uptake averaged -1 +/- 4 micromol x min(-1) x kg(-1) in metformin-treated patients (NS) and +9 +/- 3 micromol x min(-1) x kg(-1) in rosiglitazone-treated patients (P = 0.01). Both rosiglitazone and metformin treatment were associated with an increase in HGU; versus placebo, the change reached statistical significance when controlling for sex (placebo-subtracted values = +0.008 +/- 0.004 micromol x min(-1) x kg(-1) x pmol/l(-1), P < 0.03, for metformin; and +0.007 +/- 0.004, P < 0.07, for rosiglitazone). After treatment with either drug, insulin-mediated VF glucose uptake (VFGU) was higher than with placebo. In the whole dataset, changes in HGU were negatively related to changes in HbA(1c) (r = 0.43, P = 0.01) and positively associated with changes in VFGU (r = 0.48, P < 0.01). CONCLUSIONS: We conclude that both metformin and rosiglitazone monotherapy increase HGU in type 2 diabetes; direct drug actions, better glycemic control, and enhanced VF insulin sensitivity are likely determinants of this phenomenon.

Differential effects of rosiglitazone and metformin on adipose tissue distribution and glucose uptake in type 2 diabetic subjects.

We evaluated the effects of rosiglitazone (4 mg b.i.d.) and metformin (1 g b.i.d.) monotherapy for 26 weeks on adipose tissue insulin-stimulated glucose uptake in patients (n = 41) with type 2 diabetes. Before and after the treatment, glucose uptake was measured using 2-[(18)F]fluoro-2-deoxyglucose and positron emission tomography and adipose tissue masses were quantified using magnetic resonance imaging. Rosiglitazone improved insulin-stimulated whole-body glucose uptake by 44% (P < 0.01 vs. placebo). Mean body weight was unchanged in the rosiglitazone group, while it decreased by 2.0 kg in the metformin group (P < 0.05 vs. placebo). In visceral adipose tissue, glucose uptake increased by 29% (from 17.8 +/- 2.0 to 23.0 +/- 2.6 micro mol x kg(-1) x min(-1), P < 0.05 vs. placebo) in the rosiglitazone group but to a lesser extent (17%) in the metformin group (from 16.2 +/- 1.5 to 18.9 +/- 1.7 micro mol x kg(-1) x min(-1), P < 0.05 vs. baseline). Because the visceral adipose tissue mass simultaneously decreased with both treatments (P < 0.05), no change was observed in total visceral glucose uptake per depot. Rosiglitazone significantly enhanced glucose uptake in the femoral subcutaneous area, either when expressed per tissue mass (from 10.8 +/- 1.2 to 17.1 +/- 1.7 micro mol x kg(-1) x min(-1), P < 0.01 vs. placebo) or per whole-fat depot (P < 0.05 vs. placebo). In conclusion, metformin treatment resulted in improvement of glycemic control without enhancement of peripheral insulin sensitivity. The improved insulin sensitivity of the nonabdominal subcutaneous adipose tissue during treatment with rosiglitazone partly explains the enhanced whole-body insulin sensitivity and underlies the central role of adipose tissue for action of peroxisome proliferator-activated receptor gamma agonist in vivo.

Rosiglitazone but not metformin enhances insulin- and exercise-stimulated skeletal muscle glucose uptake in patients with newly diagnosed type 2 diabetes.

Rosiglitazone, a thiazolidinedione, enhances peripheral insulin sensitivity in patients with type 2 diabetes. Because the synergic action of insulin and exercise has been shown to be decreased in insulin resistance, the aim of this study was to compare the effects of rosiglitazone and metformin on muscle insulin responsiveness at rest and during exercise in patients with type 2 diabetes. Therefore, 45 patients with newly diagnosed or diet-treated type 2 diabetes were randomized for treatment with rosiglitazone (4 mg b.i.d.), metformin (1 g b.i.d.), or placebo in a 26-week double-blind trial. Skeletal muscle glucose uptake was measured using fluorine-18-labeled fluoro-deoxy-glucose and positron emission tomography (PET) during euglycemic-hyperinsulinemic clamp and one-legged exercise before and after the treatment period. Rosiglitazone (P < 0.05) and metformin (P < 0.0001) treatment lowered the mean glycosylated hemoglobin. The skeletal muscle glucose uptake was increased by 38% (P < 0.01) and whole-body glucose uptake by 44% in the rosiglitazone group. Furthermore, the exercise-induced increment during insulin stimulation was enhanced by 99% (P < 0.0001). No changes were observed in skeletal muscle or whole-body insulin sensitivity in the metformin group. In conclusion, rosiglitazone but not metformin 1) improves insulin responsiveness in resting skeletal muscle and 2) doubles the insulin-stimulated glucose uptake rate during physical exercise in patients with type 2 diabetes. Our results suggest that rosiglitazone improves synergic action of insulin and exercise.

Increased lipolysis and decreased leptin production by human omental as compared with subcutaneous preadipocytes.

Site differences in adipose tissue function may have implications for insulin-resistant conditions. In mature adipose tissue, subcutaneous adipocytes have higher leptin secretion, similar tumor necrosis factor (TNF)-alpha secretion, and lower catecholamine-stimulated lipolysis as compared with omental adipocytes. In this study, lipolysis and leptin and TNF-alpha secretion were compared between human omental and subcutaneous preadipocytes. After 16 days of incubation in a minimal differentiation medium, leptin mRNA and secretion were found to be two to eight times higher in subcutaneous than omental preadipocytes (P < 0.05). On the other hand, norepinephrine-induced lipolysis was about two times higher in the omental than in the subcutaneous preadipocytes, whereas basal lipolysis did not differ between the two regions. TNF-alpha secretion was marginally but significantly higher in the omental than in the subcutaneous preadipocytes. Preadipocyte differentiation was equal in both regions and was augmented to the same extent by different thiazolidinediones (rosiglitazone, pioglitazone, or troglitazone) in the two depots. In the presence of rosiglitazone, leptin secretion remained about three times higher and norepinephrine-induced lipolysis about six times lower in subcutaneous as compared with omental preadipocytes (P < 0.05), whereas TNF-alpha secretion and basal lipolysis were similar in preadipocytes from the two regions. These findings remained unaltered even if rosiglitazone was removed from the medium. However, leptin mRNA showed no regional differences in rosiglitazone-treated cells. Thus, regional differences in adipocyte leptin secretion as well as in norepinephrine-induced lipolysis are marked and present during different stages of preadipocyte differentiation and seem to be determined by intrinsic (i.e., primary) factors.

Mapping of early signaling events in tumor necrosis factor-alpha -mediated lipolysis in human fat cells.

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine with a proposed role in obesity-related insulin resistance. This could be mediated by increased lipolysis in adipose tissue resulting in elevated free fatty acid levels. The early intracellular signals entailed in TNF-alpha-mediated lipolysis are unknown but may involve members of the mitogen-activated protein kinase (MAPK) family. We investigated the possible contribution of MAPK in TNF-alpha-induced lipolysis in human preadipocytes. TNF-alpha activated the three mammalian MAPK, p44/42, JNK, and p38, in a distinct time- and concentration-dependent manner. TNF-alpha also induced a concentration-dependent stimulation of lipolysis with a more than 3-fold increase at the maximal dose. Lipolysis was completely inhibited by blockers specific for p44/42 (PD98059) and JNK (dimetylaminopurine) but was not affected by the p38 blocker SB203580. Use of receptor-specific TNF-alpha mutants showed that activation of MAPK is entirely mediated by the TNFR1 receptor. The results in human preadipocytes differed from those obtained in murine 3T3-L1 adipocytes in which all three MAPK were constitutively active. Thus, studies of intracellular signaling pathways obtained in different cellular contexts should be interpreted with caution. In conclusion, although TNF-alpha activates all three known MAPK in human preadipocytes, only p44/42 and JNK appear to be involved in the regulation of lipolysis.

Increases in serum leptin levels during peritoneal dialysis are associated with inflammation and a decrease in lean body mass.

Leptin, secreted from fat cells, functions as a lipostat mechanism through modulation of satiety signals. Markedly elevated leptin levels have been documented in uremic patients, especially in those who are treated by peritoneal dialysis (PD). However, the role of hyperleptinemia in uremic patients is not clear, and it is not known whether elevated leptin levels contribute to uremic anorexia and changes in body composition. In this prospective study, serum leptin, C-reactive protein (CRP), plasma insulin, and body composition (dual-energy x-ray absorptiometry) were measured in 36 patients (53 +/- 1 yr) close to start and after about 1 yr of PD. In addition, markers of dialysis adequacy and urea kinetics were followed during treatment with PD. During PD, the total body fat mass (20.5 +/- 1.0 to 22.9 +/- 1.3 kg; P < 0.01), truncal fat mass (11.5 +/- 0.7 to 13. 2 +/- 0.9 kg; P < 0.001), and serum leptin levels (20.1 +/- 3.8 to 35.6 +/- 6.8 ng/ml; P < 0.01) increased markedly, especially in patients with diabetes mellitus. Twenty-five PD patients that lost lean body mass during PD had significantly (P < 0.05) elevated initial CRP levels (14 +/- 2 mg/L) compared to 11 patients (<10 mg/L) who gained lean body mass during PD. A significant increase in serum leptin levels (20.9 +/- 4.2 to 42.7 +/- 4.0 ng/ml; P < 0.001) was observed in those patients who lost lean body mass, whereas no such change (18.4 +/- 8.4 to 19.2 +/- 6.4 ng/ml) was observed in the patients that gained lean body mass during PD treatment. The present longitudinal results demonstrate that serum leptin level and body fat content increase markedly during PD, especially in diabetic patients. Patients that lost lean body mass during PD had higher initial CRP levels and increased their serum leptin levels significantly during PD compared to those patients that gained lean body mass. Additional studies are therefore needed to elucidate the role of hyperleptinemia and inflammation in causing anorexia, protein-malnutrition, and changes in body composition during treatment with PD.