Leptin and its relation to weight loss, ob gene expression and the acute-phase response in surgical patients

Dual-energy X-ray absorptiometry scans accurately predict differing body fat content in live sheep

Background

There is considerable interest in implementing mobile scanning technology for on-farm body composition analysis on live animals. These experiments evaluated the use of dual energy X-ray absorptiometry (DXA) as an accurate method of total body fat measurement in live sheep.

Results

In Exp. 1, visceral and whole body fat analysis was undertaken in sheep with body condition scores (BCS) in the range 2 to 3.25 (scale 1: thin to 5: fat). The relationship of BCS was moderately correlated with visceral fat depot mass (r = 0.59, P < 0.01, n = 24) and whole body fat (r = 0.70, P < 0.001, n = 24). In Exp. 2, sheep with BCS in the range 2.25 to 3.75 were blood sampled to analyse circulating leptin concentrations, and were DXA scanned immediately post mortem for total body fat. Plasma leptin concentrations had low correlations with BCS (r = 0.50, P < 0.05, n = 17) and DXA body fat (r = 0.42, P < 0.05, n = 17), and no correlation with chemical body fat (r = 0.17, P > 0.05, n = 9). There was a moderate correlation between DXA body fat and BCS (r = 0.70, P < 0.01, n = 17), and DXA body fat was highly correlated with chemical body fat (r = 0.81, P < 0.001, n = 9). In Exp. 3, a series of five DXA scans, at 8-week intervals, was performed on growing sheep over a 32-week period. The average BCS ranged from 2.39 ± 0.07 (S.E.M.) to 3.05 ± 0.11 and the DXA body fat (%) ranged from 16.8 ± 0.8 to 24.2 ± 1.2. There was a moderate correlation between DXA body fat and BCS over the 32 weeks (r = 0.61, P < 0.001, n = 24).

Conclusions

Overall, these experiments indicated that there was good agreement between BCS, DXA and chemical analysis for measuring total body fat in sheep, and that DXA scanning is a valid method for longitudinal measurement of total body fat in live sheep.

Potential Biomarkers of Fat Loss as a Feature of Cancer Cachexia

Fat loss is associated with shorter survival and reduced quality of life in cancer patients. Effective intervention for fat loss in cachexia requires identification of the condition using prognostic biomarkers for early detection and prevention of further depletion. No biomarkers of fat mass alterations have been defined for application to the neoplastic state. Several inflammatory cytokines have been implicated in mediating fat loss associated with cachexia; however, plasma levels may not relate to adipose atrophy. Zinc-α2-glycoprotein may be a local catabolic mediator within adipose tissue rather than serving as a plasma biomarker of fat loss. Plasma glycerol and leptin associate with adipose tissue atrophy and mass, respectively; however, no study has evaluated their potential as a prognostic biomarker of cachexia-associated fat loss. This review confirms the need for further studies to identify valid prognostic biomarkers to identify loss of fat based on changes in plasma levels of biomarkers.

The expression of LEP, LEPR, IGF1 and IL10 in obesity and the relationship with microRNAs

Obesity is a multifactorial disease, with epigenetic alterations. Have been described modifications in the expression of some microRNAs, and some proteins related to obesity. The objective was to determine and correlate, in obese patients, the gene expression of LEP, LEPR, IGF1, IL10 and of miR-27a, miR-27b, miR-143 and miR-145. RNA was extracted from biopsies of subcutaneous fat, liver and visceral fat of 15 obese subjects submitted to bariatric surgery and of 15 non-obese subjects submitted to cholecystectomy for cDNA synthesis and for RT-PCR. The microRNAs were chosen using the TargetScan software. An increased expression of LEP and IGF1 was detected in the subcutaneous fat of the obese group compared to control, while the expression of IGF1 was higher in the control group than in the obese one. MiRNA-27a had a higher expression in the omentum of the obese patients and there was also a correlation in the expression of miRNA-145 and LEPR in the omentum of this group.

Circulating leptin levels and risk of colorectal cancer and adenoma: a case-control study and meta-analysis

PURPOSE

Equivocal results regarding the role of leptin in colorectal cancer (CRC) and adenoma (CRA) have been reported. A case-control study investigating the association of leptin with CRC risk and clinicopathological characteristics along with meta-analysis of published data on both CRC and CRA were conducted.

METHODS

Pubmed and Embase were searched for the meta-analysis, comprising 28 case-control studies amounting 3,614 CRC and 1,215 CRA cases, along with 5,220 controls. Meticulous contact with the authors of individual studies was undertaken for the provision of additional data. Pooling of standardized mean differences (SMD), relative risks (RR) and 95 % CI (random effects models), subgroup, sensitivity, and meta-regression analyses were conducted.

RESULTS

The meta-analysis suggested positive association of serum leptin with CRA (RR, 95 % CI 1.35, 1.03 to +1.76), but not CRC either at the pooled analysis on SMDs or RRs (SMD, 95 % CI 0.18, -0.04 to +0.40; RR, 95 % CI 1.04, 0.65 to +1.65). Significant heterogeneity between studies on CRC as well as between studies on CRA providing SMD was noted. Subgroup, meta-regression and sensitivity analyses highlighted potential methodology-, design-, size- and quality-related effect modifiers.

CONCLUSIONS

Meta-analysis of current evidence suggests positive association of serum leptin with CRA but not with CRC risk. Given the case-control nature of available studies, the limited number of studies on serum leptin and CRA, and the heterogeneity of CRC studies, carefully designed, prospective studies preferably reporting RRs adjusted for a variety of confounders may be warranted.

The role of cytokines and adipocytokines in zoledronate-induced acute phase reaction in postmenopausal women with low bone mass

OBJECTIVE

Patients treated with intravenous zoledronate frequently experience an acute phase reaction (APR) characterized by flu-like symptoms and increased levels of inflammatory cytokines. We aimed to define the role of various cytokines/adipocytokines in zoledronate-induced APR and develop a prognostic model for its prediction.

PATIENTS AND MEASUREMENTS

Fifty-one postmenopausal women with low bone mass were subjected to zoledronate intravenous infusion. Patients were divided into those who experienced APR (APR+) and those who did not (APR-). APR was clinically defined by body temperature and the visual analogue pain scale for musculoskeletal symptoms. White blood cell count, leucocytic subpopulations, C-reactive protein, interleukin-6, tumour necrosis factor-alpha, visfatin, resistin and leptin were measured before and 48 h following the infusion. The quantitative insulin sensitivity check index (QUICKI) and homoeostasis model of assessment - insulin resistance (HOMA-IR) were calculated to assess insulin sensitivity and resistance, respectively.

RESULTS

(APR+) patients were younger and had lower baseline visfatin and higher baseline lymphocytes and phosphate compared with APR- patients. QUICKI decreased and HOMA-IR increased in APR+ patients while remained unchanged in APR- patients. In binary logistic regression analysis, a model containing previous bisphosphonate treatment, age, body mass index, lymphocytes and visfatin, which predicted zoledronate-induced APR with 82·1% sensitivity and 73·9% specificity, was selected. In this model, lymphocytes (P = 0·010) and visfatin (P = 0·029) at baseline could independently predict APR.

CONCLUSIONS

Zoledronate-induced APR is associated with serum increases of pro-inflammatory cytokines and an increase of insulin resistance. Patients with higher lymphocytes and lower visfatin levels at baseline are at higher risk for APR.

Ocular Behçet disease: current therapeutic approaches

PURPOSE OF REVIEW

To alert physician to timely recognition and current treatment of recurrent hypopyon iridocyclitis or panuveitis in ocular Behçet disease (OBD).

RECENT FINDINGS

Interferon-α, rituximab, intravitreal triamcinolone, and biological response modifiers by tumor necrosis factor inhibitors such as infliximab and adalimumab are being used increasingly for the treatment of severe sight-threatening ocular inflammation including retinal vasculitis and cystoid macular edema (CME).

SUMMARY

Biological agents offer tremendous potential in the treatment of OBD. Given that OBD predominantly afflicts the younger adults in their most productive years, dermatologist, rheumatologist, internist, or general practitioners supervising patients with oculo-articulo-oromucocutaneous syndromes should be aware of systemic Behçet disease. Early recognition of ocular involvement is important and such patients should strongly be instructed to visit immediately an ophthalmologist, as uveitis management differs from extraocular involvements with high ocular morbidity from sight-threatening complications due to relapsing inflammatory attacks in the posterior segment of the eye. A single infliximab infusion should be considered for the control of acute panuveitis, whereas repeated long-term infliximab infusions were proved to be more effective in reducing the number of episodes in refractory uveoretinitis with faster regression and complete remission of CME.

Molecular mechanisms linking adipokines to obesity-related colon cancer: focus on leptin

Obesity is linked to increased risk of colon cancer, currently the third most common cancer. Consequently rising levels of obesity worldwide are likely to significantly impact on obesity-related colon cancers in the decades to come. Understanding the molecular mechanisms whereby obesity increases colon cancer risk is thus a focus for research to inform strategies to prevent the increasing trend in obesity-related cancers. This review will consider research on deregulation of adipokine signalling, a consequence of altered adipokine hormone secretion from excess adipose tissue, with a focus on leptin, which has been studied extensively as a potential mediator of obesity-related colon cancer. Numerous investigations using colon cell lines in vitro, in vivo studies in rodents and investigations of colon cancer patients illuminate the complexity of the interactions of leptin with colon tissues via leptin receptors expressed by the colon epithelium. Although evidence indicates a role for leptin in proliferation of colon epithelial cells in vitro, this has been contradicted by studies in rodent models. However, recent studies have indicated that leptin may influence inflammatory mediators linked with colon cancer and also promote cell growth dependent on genotype and is implicated in growth promotion of colon cancer cells. Studies in human cancer patients indicate that there may be different tumour sub-types with varying levels of leptin receptor expression, indicating the potential for leptin to induce variable responses in the different tumour types. These studies have provided insights into the complex interplay of adipokines with responsive tissues prone to obesity-related colon cancer. Deregulation of adipokine signalling via adipokine receptors located in the colon appears to be a significant factor in obesity-related colon cancer. Molecular profiling of colon tumours will be a useful tool in future strategies to characterise the influence that adipokines may have on tumour development and subsequent therapeutic intervention. Study of the molecular mechanisms linking obesity with cancer also supports recommendations to maintain a normal body weight to reduce the risk of colon cancer.

Pathophysiology of the Behçet's Disease

Behçet's disease (BD) is a multisystemic disease of unknown etiology characterized by chronic relapsing oral-genital ulcers and uveitis. Multiple systemic associations including articular, gastrointestinal, cardiopulmonary, neurologic, and vascular involvement are also observed in BD. Although the etiopathogenesis of the disease remains unknown, increased neutrophil functions such as chemotaxis, phagocytosis, and excessive production of reactive oxygen species (ROS), including superoxide anion, which may be responsible for oxidative tissue damage seen in BD, and also immunological alterations, T lymphocyte abnormalities in both subpopulation and function have been considered to be correlated with the etiopathogenesis of BD. There is some clinical evidence suggesting that emotional stress and hormonal alterations can influence the course and disease activity of BD.

Pro-inflammatory and tumour proliferative properties of excess visceral adipose tissue

Obesity has been associated with increased incidence and mortality of oesophageal and colorectal adenocarcinoma. Excess central adiposity may drive this association through an altered inflammatory milieu. Utilising a unique adipose tissue bioresource we aimed to determine the pro-tumour properties of visceral adipose tissue. Comparing subcutaneous and visceral adipose tissue depots, we observed significantly higher levels of VEGF and IL-6, along with significantly higher proportions of CD8(+) T cells and NKT cells in visceral adipose tissue. Significantly higher levels of VEGF were observed in the conditioned media from visceral adipose tissue of centrally obese compared to non-obese patients. We also report a significant increase in oesophageal and colorectal tumour cell proliferation following culture with conditioned media from visceral adipose tissue of centrally obese patients. Neutralising VEGF in the conditioned media significantly decreased tumour cell proliferation. This novel report highlights a potential mechanism whereby visceral adipose tissue from centrally obese cancer patients may drive tumour progression.

Enhanced ZAG production by subcutaneous adipose tissue is linked to weight loss in gastrointestinal cancer patients

Background:

Profound loss of adipose tissue is a hallmark of cancer cachexia. Zinc-α2-glycoprotein (ZAG), a recently identified adipokine, is suggested as a candidate in lipid catabolism.

Methods:

In the first study, eight weight-stable and 17 cachectic cancer patients (weight loss ⩾5% in previous 6 months) were recruited. Zinc-α2-glycoprotein mRNA and protein expression were assessed in subcutaneous adipose tissue (SAT), subcutaneous adipose tissue morphology was examined and serum ZAG concentrations were quantified. In the second cohort, ZAG release by SAT was determined in 18 weight-stable and 15 cachectic cancer patients. The effect of ZAG on lipolysis was evaluated in vitro.

Results:

Subcutaneous adipose tissue remodelling in cancer cachexia was evident through shrunken adipocytes with increased fibrosis. In cachectic cancer patients, ZAG mRNA was upregulated (2.7-fold, P=0.028) while leptin mRNA decreased (2.2-fold, P=0.018); serum ZAG levels were found to be unaffected. Zinc-α2-glycoprotein mRNA correlated positively with weight loss (r=0.51, P=0.01) and serum glycerol levels (r=0.57, P=0.003). Zinc-α2-glycoprotein release by SAT was also elevated in cachectic patients (1.5-fold, P=0.024) and correlated with weight loss (r=0.50, P=0.003). Recombinant ZAG stimulated lipolysis in human adipocytes.

Conclusions:

Zinc-α2-glycoprotein expression and secretion by adipose tissue is enhanced in cachectic cancer patients. Given its lipid-mobilising effect, ZAG may contribute to adipose atrophy associated with cancer cachexia in human beings.

Cancer cachexia: a systematic literature review of items and domains associated with involuntary weight loss in cancer

BACKGROUND

The concept of cancer-related anorexia/cachexia is evolving as its mechanisms are better understood. To support consensus processes towards an updated definition and classification system, we systematically reviewed the literature for items and domains associated with involuntary weight loss in cancer.

METHODS

Two search strings (cachexia, cancer) explored five databases from 1976 to 2007. Citations, abstracts and papers were included if they were original work, in English/German language, and explored an item to distinguish advanced cancer patients with variable degrees of involuntary weight loss. The items were grouped into the 5 domains proposed by formal expert meetings.

RESULTS

Of 14,344 citations, 1275 abstracts and 585 papers reviewed, 71 papers were included (6325 patients; 40-50% gastrointestinal, 10-20% lung cancer). No single domain or item could consistently distinguish cancer patients with or without weight loss or having various degrees of weight loss. Anorexia and decreased nutritional intake were unexpectedly weakly related with weight loss. Explanations for this could be the imprecise measurement methods for nutritional intake, symptom interactions, and the importance of systemic inflammation as a catabolic drive. Data on muscle mass and strength is scarce and the impact of cachexia on physical and psychosocial function has not been widely assessed.

CONCLUSIONS

Current data support a modular concept of cancer cachexia with a variable combination of reduced nutritional intake and catabolic/hyper-metabolic changes. The heterogeneity in the literature revealed by this review underlines the importance of an agreed definition and classification of cancer cachexia.

Zinc-alpha2-glycoprotein in cachexia and obesity

PURPOSE OF REVIEW

Control of adipose mass is important in the treatment of both cachexia and obesity. This review focuses on a novel adipokine, zinc-alpha2-glycoprotein (ZAG), which plays an important role in the mobilization and utilization of stored lipids.

RECENT FINDINGS

An increased lipolysis is responsible for the loss of adipose tissue in cachexia, through an increased lipolytic response to catecholamines, arising from an increased expression of hormone-sensitive lipase. In obesity, there is a decreased response of adipocytes to catecholamines and reduced expression of hormone-sensitive lipase. ZAG was identified as a lipolytic factor produced by certain cachexia-inducing tumours, and subsequently adipose tissue (both white and brown), the expression of which was found to increase in cachexia. In contrast, ZAG expression is low in obesity. ZAG not only increases lipolysis in white adipose tissue through the classical cyclic AMP pathway, but also stimulates an increase in expression of uncoupling protein-1 in brown adipose tissue, which would stimulate utilization of the release lipid to generate heat. Homozygous ZAG null mice show an increase in body weight, especially when fed a high-fat diet, whereas adipocytes from such animals show a resistance to lipolysis by catecholamines and agents that increase cyclic AMP levels.

SUMMARY

These results suggest that ZAG may play an important role in the regulation of adipose mass in obesity and cachexia.

Obesity-related genes variability in Czech patients with sporadic colorectal cancer: preliminary results

BACKGROUND

Genetic variability in obesity-related genes and the resulting phenotypes are being recognized as major risk factors for colorectal cancer and/or severity of the disease.

MATERIALS AND METHODS

A total of 102 patients (aged 68 +/- 10.2 years, 79 men and 23 women) and 101 age-matched (68.1 +/- 5.4 years old) individuals without colorectal cancer, 59 men and 42 women, were recruited. All the individuals were genotyped for the following subset of polymorphisms in obesity-related genes: angiotensinogen gene (M235T and -6A/G), in IL-6 gene (-174 G/C and -596 A/G), in leptin gene (-2548 A/G), and polymorphism Gln223Arg within the leptin receptor (LEPR) gene.

RESULTS

A significant increase in frequency of double heterozygote genotype (MTAG) of both angiotensinogen polymorphisms in males with colorectal cancer was observed when compared to control men [odds ratio (OR) = 3.77, P (corr) = 0.001]. A marginally significant difference in genotype distribution of -174 G/C IL-6 polymorphism between the patients in stage I-II compared to patients in III-IV was found (P (g) = 0.05, P (a) = 0.173). The GG genotype of -174 G/C IL-6 polymorphism in the patients in stage III-IV carries an increased risk compared to those in stage I-II (OR = 2.83, P (corr) = 0.06). Similarly, a difference in genotype distribution of Gln223Arg in LEPR gene between the patients staged I-II compared to III-IV was observed (P (g) = 0.05). The AA genotype was shown to be risky for the patients staged III-IV (OR = 3.35, P (corr) = 0.06).

CONCLUSIONS

The investigated single nucleotide polymorphisms within the genes encoding for obesity-related genes were observed to be associated both with clinical manifestation of colorectal cancer and with severity of the disease. Thus, we suggest that defined genetic variability in the genes might become DNA markers for colorectal cancer in the future.

Serum leptin levels in community acquired pneumonia (CAP) are related to nutritional status and not to acute phase reaction

To determine whether leptin in patients with CAP acts as a nutritional or as an inflammatory marker and whether leptin plays any role regarding survival, we included 222 patients diagnosed of CAP, 142 men and 80 women, median age 74 years. We did not find significant differences in serum leptin levels between CAP patients and healthy controls, even after adjusting by BMI. Serum leptin levels were directly related with BMI, body fat and muscle mass and inversely related with inflammatory markers, including pro- and anti-inflammatory cytokines. Patients with positive blood cultures showed lower serum leptin and raised inflammatory markers. Although patients who died showed lower values of serum leptin, multivariate analysis showed that the prognostic value of low serum leptin levels depends on impaired nutritional status. In conclusion, we suggest that in CAP patients, leptin does not act as an inflammatory reactant but as a nutritional marker.

Similar effects of general and spinal anaesthesia on perioperative stress response in patients undergoing haemorrhoidectomy

Surgery induces release of neuroendocrine hormones (cortisol), cytokines (interleukin-6: IL-6, tumour necrosis factor-α: TNF-α), acute phase proteins (C-reactive protein: CRP, leptin). We studied the effects of general and spinal anaesthesia on stress response to haemorrhoidectomy. Patients were assigned to general and spinal anaesthesia groups (n = 7). Blood samples were drawn before induction and 24 hours after surgery. Perioperative levels of IL-6, TNF-α, CRP, cortisol, and leptin were comparable among the groups. Twenty four hours after surgery, TNF-α and cortisol did not change; IL-6 and CRP increased significantly in all patients. Significant increase in leptin levels was found in patients undergoing spinal anaesthesia. Except for the increase in leptin levels, there was no significant difference related to the effects of general and spinal anaesthesia.

Leptin: at the crossroads of energy balance and systemic inflammation

In addition to playing a central role in energy homeostasis, leptin is also an important player in the inflammatory response. Systemic inflammation is accompanied by fever (less severe cases) or hypothermia (more severe cases). In leptin-irresponsive mutants, the hypothermia of systemic inflammation is exaggerated, presumably due to the enhanced production and cryogenic action of tumor necrosis factor (TNF)-alpha. Mechanisms that exaggerate hypothermia can also attenuate fever, particularly in a cool environment. Another common manifestation of systemic inflammation is behavioral depression. Along with the production of interleukin (IL)-1beta, this manifestation is exaggerated in leptin-irresponsive mutants. The enhanced production of TNF-alpha and IL-1beta may be due, at least in part, to insufficient activation of the anti-inflammatory hypothalamo-pituitary-adrenal axis by immune stimuli in the absence of leptin signaling. In experimental animals and humans that are responsive to leptin, suppression of leptin production under conditions of negative energy balance (e.g., fasting) can exaggerate both hypothermia and behavioral depression. Since these manifestations aid energy conservation, exaggeration of these manifestations under conditions of negative energy balance is likely to be beneficial.

Leptin: a proliferative factor for breast cancer? Study on human ductal carcinoma

Mammary adipose tissue is an important source of paracrine mitogens and anti-mitogens, including insulin-like growth factor, transforming growth factors, and cytokines (especially, TNFalpha and IL-1beta). Nevertheless, it is also an important source of the adipocytokine, leptin. Recently, leptin was reported to stimulate the proliferation of various cell types (pancreatic beta cells, prostate, colorectal, lung, etc.) as a new growth factor. It was also shown to stimulate the proliferation of breast cancer cell lines. In this study, we conducted an immunohistochemical analysis of leptin expression in normal tissue and benign and malignant ductal breast cell, representing the different states of the invasion process. We determined for the first time that leptin is expressed both by ductal breast tumors and by benign lesions as atypical hyperplasia. This suggests that leptin may be taken up or synthesized by all modified ductal breast cells, and may prove a proliferative factor. Moreover, leptin is unexpressed by normal tissue in the healthy breast but is exhibited by the normal tissue in near vicinity of the malignant ductal breast lesions. We also postulated that leptin may be a prognostic or diagnostic factor for ductal breast cancer. These putative hypotheses require further study.

Comparison of Gene Expression in Intra-Abdominal and Subcutaneous Fat: A Study of Men with Morbid Obesity and Nonobese Men Using Microarray and Proteomics

Extent of intra-abdominal fat had significant linear relations with six metabolic coronary risk factors: systolic and diastolic blood pressure, fasting blood concentrations of glucose, high density lipoprotein (HDL) cholesterol, triglyceride, and plasminogen activator inhibitor-1. Tumor necrosis factor-alpha and adiponectin can be biological mediators from the intra-abdominal fat to the metabolic coronary risk factors. Complementarily, we describe a new study that will analyze the gene expression in intra-abdominal and subcutaneous fat on mRNA and protein level using high throughput methods. The study will elucidate further whether intra-abdominal obesity is the common denominator for the different components of the metabolic syndrome.

Adipose tissue in Walker 256 tumour-induced cachexia: possible association between decreased leptin concentration and mononuclear cell infiltration

The adipose tissue (AT) is severely affected by cachexia, a paraneoplastic syndrome, which increases the morbidity and mortality of cancer. There is, however, a heterogeneous response to the condition, according to the AT depot. As plasma leptin concentration has been often reported to vary in cachexia, we have measured (species specific radioimmunoassay) the local concentration of leptin in three AT depots: retroperitoneal (RPAT), epididymal (EAT) and mesenteric (MES) of Walker 256 tumour-bearing rats. A reduced concentration of leptin ( P<0.0001) was found in all the depots and in the plasma of the cachectic rats, compared with controls already from day 4 after tumour cell injection. The presence of a cell infiltrate was observed in all AT obtained from the tumour-bearing animals. Ultrastructural analysis, along with immunocytochemistry for RT1B (indicating the presence of MHCII) and using antibody against mononuclear phagocytes, showed the cells to be macrophages. The profile of TNFalpha and PGE2 secretion by the infiltrate was investigated (commercial kits). There was increased production of both factors by the cells of all AT ( P<0.05) compared with peritoneal macrophages obtained from the cachectic rats, while the cells isolated from MES showed the highest synthesis of TNFalpha. The results suggest a possible modulation of the chronic locally produced TNFalpha and PGE2 upon leptin synthesis by the AT of the cachectic rats.

Cancer anorexia-cachexia syndrome: cytokines and neuropeptides

PURPOSE OF REVIEW

Cancer anorexia-cachexia syndrome is observed in 80% of patients in the advanced stages of cancer and is a strong independent risk factor for mortality. Numerous cytokines produced by tumor and immune cells, interacting with the neuropeptidergic system, mediate the cachectic effect of cancer. Since there is currently no effective pharmacological treatment and the anorexia-cachexia syndrome continues to be defined biochemically, we review the role of cytokines and neuropeptides in this process.

RECENT FINDINGS

Currently data suggest that cancer anorexia-cachexia syndrome results from a multifactorial process involving many mediators, including hormones (e.g. leptin), neuropeptides (e.g. neuropeptide Y, melanocortin, melanin-concentrating hormone and orexin) and cytokines (e.g. interleukin 1, interleukin 6, tumor necrosis factor alpha and interferon gamma). It is likely that close interrelation among these mediators exists in the hypothalamus, decreasing food intake and leading to cachexia.

SUMMARY

In the pathogenesis of cancer anorexia, cytokines play a pivotal role influencing the imbalance of orexigenic and anorexigenic circuits that regulate the homeostatic loop of body-weight regulation, leading to cachexia. Interfering pharmacologically with cytokine expression or neural transduction of cytokine signals can be an effective therapeutic strategy in anorectic patients before they develop cancer anorexia-cachexia syndrome.

Serum leptin concentration and advanced gastrointestinal cancers: a case controlled study

BACKGROUND

Serum leptin level is associated with appetite and energy expenditure in healthy individuals. We aimed to evaluate the serum leptin concentration and the other factors which may be associated with weight loss in patients with advanced gastrointestinal cancer.

METHODS

Forty-four patients with advanced gastrointestinal cancer (25 gastric and 19 colorectal cancer) and 25 healthy controls were enrolled. Serum leptin levels were measured as ng/ml via enzyme linked immuno-sorbent assay (ELISA) method in all subjects. The difference in serum leptin concentration between cancer and control group, the factor associated with its serum level and the relationship between serum leptin concentration and weight loss was evaluated.

RESULTS

Serum leptin concentration of cancer group was significantly lower than controls (p = 0.002). Female subjects had significantly higher serum leptin concentration than male subjects in control group (p = 0.01), while not in cancer group (p > 0.05). Serum leptin concentration was significantly related with gender in controls (p = 0.023, beta = 0.479), while no gender difference was observed in cancer group (p > 0.05). No relationship was found between serum leptin concentration and weight loss percentage in cancer group in linear regression analysis (p > 0.05). No significant difference was observed in serum leptin concentrations between colon and gastric cancer sub-groups (p > 0.05).

CONCLUSION

Independently from the site of gastrointestinal tract, serum leptin concentration in advanced gastrointestinal cancer is lower than controls and it is not a determinant factor in weight loss. In contrast to healthy subjects, gender does not effect the serum leptin concentration in patients with advanced gastrointestinal cancer.

Circulating concentrations of "free" leptin in relation to fat mass and appetite in gastrointestinal cancer patients

Recent studies have suggested that circulating concentrations of leptin might play a role in cancer cachexia. In the first part of the study, we compared circulating concentrations of free and total leptin, percent fat mass, and the inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6), together with appetite score, in age- and gender-matched healthy controls (n = 11) and advanced gastrointestinal cancer patients (n = 26). In the second part of the study, the same measurements were repeated before and after megestrol acetate treatment of weight-losing gastrointestinal cancer patients (n = 10). Body mass index and percent fat mass were significantly lower (P < 0.05) and IL-6 and CRP were significantly higher (P < 0.05) in cancer patients than in controls. There was no difference in the percentage of leptin bound in the circulation between controls and cancer patients. Circulating "free" leptin concentrations correlated with percent fat mass in controls (r = 0.745, P = 0.008) and cancer patients (r = 0.600, P = 0.001). In cancer patients, circulating leptin concentrations, either free or total, were not correlated with IL-6 or CRP concentrations. When adjusted for fat mass, the circulating concentrations of free and total leptin were significantly lower in the cancer patients (P < 0.01). Megestrol acetate treatment significantly increased circulating free and total leptin concentrations in the cancer patients (P < 0.05). There was a significant positive correlation between the change in circulating concentrations of free and total leptin and the change in percent fat mass (r = 0.685, P < 0.05 and r = 0.661, P < 0.05, respectively). The results of the present study indicate that the proportions of free and bound leptin in the circulation do not differ between normal subjects and patients with gastrointestinal cancer and in both groups are related to fat mass. Furthermore, the increase in circulating leptin concentrations after megestrol acetate treatment is not associated with any alteration in leptin binding.

No influence of surgical stress on postoperative leptin gene expression in different adipose tissues and soluble leptin receptor plasma levels

As part of the postsurgical stress response, plasma leptin levels increase in-between 12 h postoperatively.

OBJECTIVE

To study the kinetics of leptin gene expression in different adipose tissues before and after severe surgical trauma in children and adults.

METHODS

In 22 adults and 23 children with cardiac and 19 adult patients with abdominal surgery, we measured plasma leptin concentrations preoperatively, 4 and 10-17 h postoperatively and quantified leptin mRNA expression by TaqMan real-time PCR in adipose tissue taken at the beginning and the end of surgery from subcutaneous, intrathoracic, omental and mesenteric fat. Plasma-soluble leptin receptor levels were measured in 23 children after cardiosurgery.

RESULTS

Plasma leptin levels doubled between 4 and 10-17 h postoperatively in adults (p < 0.001) as well as in children (p = 0.0002) with cardiac surgery. After abdominal surgery, 10-17 h postoperatively, plasma leptin concentrations increased significantly (p < 0.05). During the operation, leptin gene expression did not change in neither of the patient groups. Plasma-soluble leptin receptor levels decreased immediately after the onset of surgery and remained unchanged thereafter.

CONCLUSIONS

Leptin gene expression is not up-regulated during surgery. The measured increase in plasma leptin after surgery does not result from elevated levels of soluble leptin receptor but may follow an up-regulation of leptin gene expression later after the operation due to postsurgical metabolic changes.

Plasma leptin levels in patients with burn injury: a preliminary report

The purpose of this study was to investigate the relationship between the plasma leptin level and clinical parameters in patients with burn injury. Six patients with burn injury were admitted to the Emergency and Critical Care Medicine Center of St. Marianna University Hospital within 1h after injury. Plasma levels were monitored for leptin, proinflammatory cytokines (interleukin (IL)-1 beta, IL-6, tumor necrosis factor alpha (TNF alpha)), stress-related parameters (adrenocorticotropic hormone (ACTH), cortisol, and C-reactive protein (CRP)). The change in individual plasma leptin levels did not show similar pattern in all these patients. However, leptin levels remained within the normal range, except in a patient (Case 1) complicated with severe hypovolemic shock. Plasma ACTH and cortisol levels were also elevated in most of the patients. Examination of relationships among plasma leptin, proinflammatory cytokines, and stress-related parameters revealed a significant positive correlation between the plasma leptin level and IL-1 beta or IL-6. These results suggest that the plasma leptin level may have some relations to plasma proinflammatory cytokines in pathophysiologic responses to critical conditions of burn injury.

Effects of dietary fat type and energy restriction on adipose tissue fatty acid composition and leptin production in rats

To investigate whether dietary fatty acid (FA) composition and energy restriction (ER) interactively influence obese (ob) gene expression, rats consumed diets containing beef tallow, safflower, or fish oil ad libitum (AL) or at 60% AL intake. Circulating leptin concentrations were higher (P < 0.0001) after AL feeding, but were not influenced by dietary fat. ER decreased (P < 0.0001) weight gain and visceral adipose weight, which were positively correlated (r = 0.40 P < 0.001, r = 0.58 P < 0.0001) with circulating leptin levels. Visceral adipose ob mRNA levels were greater in animals fed unsaturated fats, particularly safflower oil, which had the highest ob mRNA levels. Circulating leptin levels did not parallel ob mRNA levels, except for the greater abundance detected in AL adipose in comparison to ER animals. In addition, visceral FA profiles reflected dietary fat source and were influenced by an interaction of dietary fat and energy. These data demonstrate that dietary fat, particularly from a plant or marine source, and ER interactively influence ob mRNA levels; however, alterations in ob mRNA do not confer changes in circulating leptin, with the exception of ER, which is a key determinant. Thus, dietary intake is an important regulator of leptin production; however, the significance of these modest changes in diet-induced obese animals requires further study.

Leptin and energy metabolism in pulmonary tuberculosis

BACKGROUND

Pulmonary tuberculosis is the classic cause of "consumption," but the pathogenesis of such wasting is largely unknown. Animal studies in other conditions suggest that leptin may be a mediator between proinflammatory cytokine activity and wasting.

OBJECTIVE

We tested whether the leptin concentration, after control for body fat mass, is higher during active pulmonary tuberculosis than after recovery and whether it correlates with energy metabolism and proinflammatory cytokine activity.

DESIGN

Nondiabetic adults with pulmonary tuberculosis (n = 32) were recruited into a prospective observational study. Patients found to be antibody positive for human immunodeficiency virus were excluded from the study. Dual-energy X-ray absorptiometry, indirect calorimetry, and food intake protocols were performed at baseline and after 1 and 6 mo of tuberculosis treatment. Fasting plasma leptin, tumor necrosis factor alpha and its soluble receptor, and interleukin 6 were measured by enzyme-linked immunosorbent assay.

RESULTS

Resting energy expenditure was close to Harris-Benedict predictions and did not change significantly during treatment, but energy intake increased. Leptin concentration was correlated in a log-linear fashion with percentage body fat but was independent of cytokines and energy intake. There was no significant difference in leptin, corrected for energy balance and fat mass, at baseline and after 1 and 6 mo of treatment.

CONCLUSIONS

These data are compatible with recovery from anorexia or starvation without discernible hyper- or hypometabolism. The close correlation of leptin with body fat mass is similar to observations in healthy subjects. No additional influence of disease state or proinflammatory cytokine activity was found. Leptin does not appear to be a component of the immune response to human pulmonary tuberculosis, and thus it cannot account for the weight loss and anorexia associated with tuberculosis.

Low serum leptin levels and malnutrition in chronic alcohol misusers hospitalized by somatic complications

AIMS

Leptin is a peptide produced by fat cells which regulates fat mass by decreasing food intake and increasing resting energy expenditure, so an increase of serum leptin could be an indicator of malnutrition. Our objective was to determine serum leptin levels (at admission and on the 15th day) in 79 male alcohol misusers, hospitalized by somatic complications, who drink more than 80 g ethanol/day, and to analyse its relationships with nutritional status assessed by anthropometry and dual-energy X-ray absortiometry (DEXA), insulin-like growth factor (IGF-1) and its binding protein (IGF1BP-3); acute phase reaction assessed by C-reactive protein (CRP), interleukin-6 (IL-6) and type II soluble receptor of tumour necrosis factor (TNF) (sTNFRII); serum oestradiol and testosterone; and the amount and duration of ethanol intake, the smoking habit and the presence of liver cirrhosis.

METHODS

Patients were admitted through the emergency room, and blood for the above-mentioned determinations was taken at 08.00 on the following day, so none of the patients was acutely intoxicated at this time. The control group was composed of 32 healthy male (age-matched) subjects.

RESULTS

Malnutrition was frequent among alcoholics. Serum leptin levels were closely related to total fat both in controls and in alcoholics. Serum leptin levels were decreased in alcoholics, even after adjusting for the amount of fat. Those alcoholics who reported anorexia and weight loss showed decreased leptin levels. After 15 days of hospitalization, serum leptin did not increase, in contrast with LDL cholesterol, serum albumin, prealbumin, IGF-1, IGF1BP-3 and testosterone which increased, whereas oestradiol and acute phase reactants, such as CRP, IL-6 and sTNFRII, were decreased. Serum leptin was not related to gonadal hormones at admission, but on day 15 we found a negative correlation between leptin and testosterone, and a positive one with oestradiol.

CONCLUSIONS

Serum leptin levels are related to many factors, e.g. fat mass, age, smoking, serum testosterone and oestradiol levels, growth factors such as IGF-1 and CRP, and cytokines, such as IL-6 and sTNFRII. The most important of these is fat mass, as shown by multivariate analysis. Since serum leptin levels are decreased in alcohol misusers, we consider this decrease to be a consequence of a low fat mass.

Serum leptin concentration is increased in patients with Behçet's syndrome and is correlated with disease activity

Background Behçet's syndrome is a systemic, relapsing immuno-inflammatory disease with a generalized vasculitis of the microvasculature endothelial dysfunction. Leptin, a recently discovered neuroendocrine hormone, is a metabolic peptide that appears to be involved. Serum proinflammatory cytokines upregulate leptin levels and leptin itself directly induces nitric oxide production from endothelial cells with its specific receptors.

OBJECTIVES

To detect changes of serum leptin concentrations in patients with Behçet's syndrome compared with age- and sex-matched healthy volunteers by using enzyme-linked immunosorbent assay. We also investigated whether disease activity or the duration of Behçet's syndrome correlates with leptin concentration.

METHODS

Thirty-five consecutive patients with Behçet's syndrome (41.2 +/- 8.4 years, 16 male, 19 female) and 20 age- and sex-matched healthy control subjects (40.4 +/- 10.91 years, nine male, 11 female) were included in this study. The body mass index (BMI) [weight (kg) height(-1) (m(2))] was calculated for subjects at study enrollment. We measured serum leptin with a leptin enzyme immunoassay kit, and acute-phase reactants, including erythrocyte sedimentation rate, alpha1-antitrypsin, alpha 2-macroglobulin and neutrophil count. The Mann-Whitney U-test was used for statistical analysis and P < 0.05 was considered significant. Values were expressed as mean +/- SD.

RESULTS

The gender ratio, age and BMI were not substantially different among Behçet's patients and controls. The mean serum leptin concentrations in patients with Behçet's syndrome (16.8 +/- 7.49 ng mL(-1)) were significantly (P < 0.001) higher than in healthy control volunteers (7.5 +/- 2.77 ng mL(-1)). Active Behçet's patients had significantly (P = 0.001) higher leptin concentrations (20.5 +/- 7.99 ng mL(-1)) when compared with patients in inactive periods (12.8 +/- 4.43 ng mL(-1)). In addition, patients with longer disease duration (mean, 20.1 +/- 5.15 years) had also significantly (P = 0.013) higher leptin concentrations (20.2 +/- 8.52 ng mL(-1)) than those with shorter disease duration (13.4 +/- 4.52 ng mL(-1)) (mean, 7.4 +/- 3.29 years). All acute-phase reaction parameters were found to be significantly (for each, P < 0.01) increased in active disease.

CONCLUSIONS

Leptin may have a role in modulating endothelial function and may be involved in mechanisms for vessel endothelium repair, during an exacerbation as well as in chronic disease.

Leptin role in advanced lung cancer. A mediator of the acute phase response or a marker of the status of nutrition?

Leptin is an anorexia inductor peptide produced by adipocytes and related to fat mass. Leptin is also produced by fat under proinflammatory cytokine action. Our objective is to study serum leptin levels in relation to nutritional status and acute phase response in advanced-stage non-small cell lung cancer.Seventy-six patients newly diagnosed of non surgical non-small cell lung cancer before chemotherapy treatment and 30 healthy controls were included. BMI, serum leptin and cholesterol levels and lymphocyte count were decreased in lung cancer patients. Cytokine IL-6, TNF-alpha, sTNF-RII, sIL-2R, IL-12, IL-10 and IFN-gamma, and other acute phase reactants as alpha1 antitrypsin, ferritin, CRP and platelets were all raised in patients, whereas the IL-2 was decreased. We found a direct relationship between leptin and other indicators of the status of nutrition, especially total fat mass. We also found a close relationship between the status of nutrition and the performance status (Karnofsky index). However, serum leptin and nutritional status were inversely correlated with acute phase proteins and proinflammatory cytokines, suggesting a stress-type malnutrition. Although serum leptin levels, nutritional status and Karnofsky index are related to survival, at multivariate analysis they all were displaced by the acute phase reaction markers. These results suggest that cancer anorexia and cachexia are not due to a dysregulation of leptin production. Circulating leptin concentrations are not elevated in weight-losing cancer patients and are inversely related to the intensity of the inflammatory response. In advanced lung cancer patients serum leptin concentrations only depend on the total amount of fat.

Serum leptin concentrations after surgery in young rats

OBJECTIVES

We describe changes in serum leptin concentrations after surgery (laparotomy, partial hepatectomy, splenectomy, and unilateral nephrectomy) in young male rats. Because we presumed that pain and inflammation would influence food intake and subsequent leptin release, laparotomized and partially hepatectomized rats were treated with ibuprofen.

METHODS

Preoperative blood samples were taken from the retroorbital sinuses, and postoperative blood samples were taken from the aorta, vena portae, and vena cava 18 h after surgery. Serum leptin concentrations were estimated by radioimmunoassay.

RESULTS

Pre- and postoperative serum leptin concentrations did not differ significantly in rats with partial hepatectomy (5.1 +/- 0.4 versus 4.2 +/- 1.1 microg/L), splenectomy (6.1 +/- 0.4 versus 5.0 +/- 0.6 microg/L), or unilateral nephrectomy (4.1 +/- 0.7 versus 5.0 +/- 1.3 microg/L). Significant decreases in serum leptin were observed after laparotomy (8.1 +/- 0.9 versus 3.7 +/- 0.5 microg/L), laparotomy plus ibuprofen treatment (8.9 +/- 1.6 versus 3.1 +/- 0.4 microg/L), and partial hepatectomy plus ibuprofen treatment (5.4 +/- 0.6 versus 3.2 +/- 0.3 microg/L). We observed no significant differences in serum leptin concentrations measured in different regions of the body.

CONCLUSIONS

Surgical interventions in young rats are accompanied by decreases in serum leptin. The liver, spleen, and kidney may participate in leptin clearance. Ibuprofen treatment leads to additional decreases in serum leptin concentrations.