Plasma concentrations of interleukin-1-beta, interleukin-6 and tumor necrosis factor-alpha, and of their soluble receptors and receptor antagonist in anorexia nervosa

A transdiagnostic and diagnostic-specific approach on inflammatory biomarkers in eating disorders: A meta-analysis and systematic review

Eating disorders (EDs) are severe mental illnesses with a multifactorial etiology and a chronic course. Among the biological factors related to pathogenesis and maintenance of EDs, inflammation acquired growing scientific interest. This study aimed to assess the inflammatory profile of EDs, focusing on anorexia nervosa, bulimia nervosa, and including for the first time binge eating disorder. A comprehensive research of existing literature identified 51 eligible studies for meta-analysis, comparing levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), osteoprotegerin (OPG), soluble receptor activator of nuclear factor kappa-B ligand (sRANKL), interleukin-1β (IL-1β), and interleukin-10 (IL-10) between patients with EDs and healthy controls (HCs). The systematic review explored other inflammatory biomarkers of interest, which did not meet the meta-analysis criteria. Results revealed significantly elevated levels of TNF-α, OPG, sRANKL, and IL-1β in patients with EDs compared to HCs. Additionally, the results highlighted the heterogeneity of inflammatory state among patients with EDs, emphasizing the need for further research into the association between inflammatory biomarkers and psychopathological correlates. This approach should transcend categorical diagnoses, enabling more precise subcategorizations of patients. Overall, this study contributed to the understanding of the inflammatory pathways involved in EDs, emphasizing potential implications for diagnosis, staging, and targeted interventions.

Inflammatory profiles in women with eating disorder: Linking inflammatory biomarkers to clinical phenotypes

INTRODUCTION

Eating disorders (ED) represent a group of very complex and serious diagnoses characterized by emotional dysregulation and impulsivity. New approaches are necessary to achieve effective diagnosis and treatments. Shifting biomarker research away from the constraints of diagnostic categories may effectively contribute to a dimensional differentiation across disorders according to neurobiology (e.g., inflammatory biomarkers). Thus, the aim of our study was to identify inflammatory profiles in patients with ED.

METHODS

A sample of 100 women with an ED (23.4 ± 8.55 years) and 59 healthy controls (HC) (20.22 ± 4.18 years) was used. K-means cluster analysis was followed to identify inflammatory clusters considering seven blood biomarkers (iNOS, TNFα, COX2, p38, ERK, TBARS and PPARγ). Moreover, a wide assessment of clinical features was conducted.

RESULTS

Two distinct clusters were identified. Cluster 1 patients were characterized by higher inflammatory levels of TNF-α, COX2, p38, and ERK, and had more restrictive anorexia diagnosis than cluster 2. Cluster 2 participants showed higher inflammatory levels of iNOS and were older than cluster 1 and controls and had lower BMI than HC. In addition, they had higher levels of bulimic symptoms than those from the cluster 1 and HC, and higher impulsivity than HC. All ED patients (regardless of cluster) showed higher ED symptoms and more trauma than HC.

CONCLUSIONS

Our study revealed that inflammatory dysfunction may be linked with clinical endophenotypes in ED, one more restrictive (cluster 1) with an inflammation/oxidative endophenotype more cytokine and MAPK/ERK mediated, and the other more impulsive, with more bulimic symptoms (cluster 2) with NO free radical high output source iNOS. Trauma seems to be a vulnerability factor for both endophenotypes.

Anorexia Nervosa in vivo cytokine production: a systematic review

INTRODUCTION

The underlying psychobiology that contributes to Anorexia Nervosa (AN) onset and disease progression remains unclear. New research is emerging suggesting a possible link between inflammation and a variety of mental illnesses. Alterations of cytokines may play a role in the pathogenesis of AN. Some studies have found differences in the cytokine profile of those with AN compared to healthy controls, but results are heterogeneous. The aim of this work was to systematically review existing studies investigating in-vivo cytokine production in those with AN before and after weight restoration compared to controls.

METHODS

A comprehensive literature search of four electronic databases (PubMed, PsychInfo, EMBASE and CINAH) was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to identify human in-vivo studies investigating the relationship between AN and cytokine production. Data extracted from included studies related to population characteristics (e.g. age, gender, mean mBMI/%IBW), cytokine measurement and relevant findings. Confounding factors (e.g. smoking status, co-morbid mental illness, menstruation status) were also collected.

RESULTS

36 studies were eligible for this systematic review of which the majority were conducted in Europe (77.8%) and involved female subjects (97.2%). Those with AN ranged in age from 13 to 47 years and had an illness duration of 3 months to 24 years. 15 candidate cytokines and 3 receptors were identified (TNF-alpha, IL-6, IL-1B, CRP, IL-2, IL-7, IL-10, IFN-γ, TNF-R2, IL-1 α, IL-15, TNF-R1, IL-17, IL-18, TGF-B1, IL-12, IL-6R and TGF-B2) exploring in-vivo levels in patients with AN and comparing to controls. TNF-alpha and IL-6 were the most extensively studied with IL-6 being significantly elevated in 4 out of 8 (50%) of longitudinal studies when comparing AN patients at baseline compared to post weight restoration. Following weight restoration, there was no difference in IL-6 levels when comparing to HC in 7 of 8 (87.5%) longitudinal studies examined.

CONCLUSIONS

The most promising cytokine potentially involved in the pathogenesis of AN appears to be IL-6, and possibly TNF-alpha pathways. The heterogeneity of clinical and methodology factors impedes the generalizability of results. Future studies may wish to address these methodological shortcomings as alterations in cytokine levels in AN could act as therapeutic targets assisting with weight restoration and psychopathology and may offer diagnostic potential.

Expression of immune-related proteins and their association with neuropeptides in adolescent patients with anorexia nervosa

Anorexia nervosa (AN) is a metabo-psychiatric disorder where alterations of cytokines, neuropeptides, neurotransmitters, and the interactions between these factors can play an important role. Thus, the primary goal of the presented study was a cross-sectional analysis of immune-related proteins in patients with AN. Moreover, the correlations between these molecules and selected neuropeptides were studied. Twenty-five adolescent inpatients girls in the acute stage of a restrictive type of AN were enrolled in the study within the first year of the disease. Additionally, thirty similar in age and height controls (CG) were also assessed. The levels of 24 immune-related proteins, including cytokines, chemokines, and proteases, were measured. Moreover, selected adipocytokines, gastrointestinal hormones, and centrally produced neuropeptides levels were determined. Finally, the correlations between these molecules were analyzed. The fasting levels of CXCL1, CXCL9, FGF2, GrB, IL1, IL6, IL8, MMP8, MMP9, CTSS were statistically lower in AN than in the CG. The concentrations of many immune-related proteins remain unchanged despite their metabolic and mental condition. Moreover, significant correlations were found between leptin and CXCL1, CXCL9, GrB, IL1, IL6, and MMP8. Leptin receptors were correlated with GrB, while resistin was associated with MMP9. Our findings suggest that the initial stage of restrictive AN among adolescents within the first year of the disease is not connected with a pro-inflammatory state. Some immune-related protein changes may be associated with altered neuropeptides, primarily leptin, its receptors, and resistin. Future research should clarify which changes are primary and secondary to weight loss and whether these changes normalize with increasing weight. This would aid in understanding the complex etiopathogenesis of AN and in the search for new methods of treatment.

Lower serum levels of IL-1β and IL-6 cytokines in adolescents with anorexia nervosa and their association with gut microbiota in a longitudinal study

INTRODUCTION

Anorexia nervosa (AN) is an often chronic and debilitating psychiatric disease whose etiology is not completely understood. Recently, a potential role of inflammation has emerged in other psychiatric diseases, such as depression, PTSD and schizophrenia. The first results in adults with AN seemed to confirm a low-grade proinflammatory state until recent studies presented more differential findings. Studying adolescents with a shorter illness duration and fewer confounding factors might help elucidate the role of inflammation in the underlying pathophysiology of AN; however, the few available studies in adolescents remain ambiguous, and no longitudinal data are available in this age range.

METHODS

We examined the proinflammatory cytokines Tumor Necrosis Factor-alpha (TNF-α), Interleukin (IL)-1β, IL-6, IL-15, and the cytokine-receptor IL-6 Receptor alpha (IL-6 Rα) in the serum of twenty-two hospitalized female adolescent patients with AN longitudinally at admission and discharge and compared their results to nineteen healthy controls (HC). We also collected clinical data and stool samples that were analyzed with 16S rRNA amplicon sequencing to explore potential influencing factors of cytokine changes.

RESULTS

TNF-α serum levels were significantly elevated in patients with AN at admission, while IL-1β and IL-6 levels were lower at admission and discharge than in HC. After treatment, we also found significantly elevated levels of IL-6 Rα compared to HC, while IL-15 did not show significant changes. Exploratory analyses revealed positive associations of cytokine and genus-level changes between admission and discharge for IL-1β (Bacteroides) and IL-15 (Romboutsia), and negative associations for IL-15 (Anaerostipes) and TNF-α (uncultured Lachnospiraceae).

CONCLUSION

We confirmed a previous finding of elevated levels of TNF-α also in adolescents with AN; however, the reduced IL-1β and IL-6 levels differed from the mostly increased levels found in adults. A mixed pro- and anti-inflammatory state appears to be present in adolescents, potentially due to their shorter illness duration. The gut microbiota, with its regulatory function on cytokine production, might play a role in mediating these inflammatory processes in AN and could offer targets for new therapeutic approaches.

Brain Volume Loss, Astrocyte Reduction, and Inflammation in Anorexia Nervosa

Anorexia nervosa is the third most common chronic disease in adolescence and is characterized by low body weight, body image distortion, weight phobia, and severe somatic consequences. Among the latter, marked brain volume reduction has been linked to astrocyte cell count reduction of about 50% in gray and white matter, while neuronal and other glial cell counts remain normal. Exact underlying mechanisms remain elusive; however, first results point to important roles of the catabolic state and the very low gonadal steroid hormones in these patients. They also appear to involve inflammatory states of "hungry astrocytes" and interactions with the gut microbiota. Functional impairments could affect the role of astrocytes in supporting neurons metabolically, neurotransmitter reuptake, and synapse formation, among others. These could be implicated in reduced learning, mood alterations, and sleep disturbances often seen in patients with AN and help explain their rigidity and difficulties in relearning processes in psychotherapy during starvation.

Longitudinal associations between circulating interleukin-6 and C-reactive protein in childhood, and eating disorders and disordered eating in adolescence

OBJECTIVE

Few studies have explored the association between inflammation and eating disorders and none used a longitudinal design. We investigated the association between serum-levels of interleukin 6 (IL-6) and C-reactive protein (CRP) measured in childhood and eating disorders and related behaviours and cognitions in adolescence in a large general population sample.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC). Our exposures were thirds of IL6 and CRP derived from serum measurements taken at age nine years, and outcomes were eating disorder diagnoses and self-reported disordered eating behaviours at ages 14, 16, and 18 years. We used univariable and multivariable multilevel logistic regression models adjusting for a number of potential confounders, including sex, fat mass, and pre-existing mental health difficulties.

RESULTS

Our sample included 3480 children. Those in the top third of CRP had lower odds of binge eating (odds ratio(OR):0.62, 95% confidence interval (CI):0.39,1.00,p "equals" 0.05) and fasting (OR:0.63, 95% CI:0.38,1.07,p "equals" 0.09) after adjustment for confounders. We also observed weak associations of comparable magnitude for purging, anorexia nervosa, and bulimia nervosa. We did not find any associations between levels of IL6 and any of the outcomes under study.

CONCLUSIONS

There was little evidence of an association between CRP and IL-6 and adolescent eating disorder outcomes. The inverse association observed between CRP and binge eating was unexpected, so caution is needed when interpreting it. One possible explanation is that higher CRP levels could have a protective role for disordered eating by affecting appetitive traits.

Dysfunction of inflammatory pathways in adolescent female patients with anorexia nervosa

BACKGROUND

The pathogenesis of Eating Disorders is still unknown. However, a growing body of evidence shows that there are changes in cytokine levels and an alteration in the stress response in patients with anorexia nervosa (AN). For this reason, we decided to test whether there are differences in immune parameters involved in the regulation of the inflammatory response between female adolescents with AN and healthy adolescents.

METHODS

The sample 27 drug-naïve AN patients the study sample included 27 AN patients at a very early stage of the disease and 23 healthy controls. Plasma and peripheral blood mononuclear cells (PBMCs) were obtained for biochemical study.

RESULTS

Plasma levels of the pro-inflammatory cytokines TNF-α and IL-1β were significantly increased in patients with AN, while the levels of prostaglandins PGE₂ (proinflammatory) and 15d-PGJ₂, (anti-inflammatory) were lower compared with controls. Protein expression in PBMCs of cyclooxygenase-2 (COX-2) and the activated forms of the mitogen-activated protein kinases p38 and ERK were also increased in the AN group. Expression levels of the anti-inflammatory factor peroxisome proliferator-activated receptor gamma (PPARγ) were significantly decreased in patients. Plasma levels of lipid peroxidation markers -TBARS- were not increased in patients with AN. Components of the biochemical inflammatory response (COX-2, PGE₂, TBARS, 15d-PGJ₂, ERK, p65 NFκB) and glucocorticoid receptor -GR- expression and the scores on the impulsivity measures in the BARRATT, EDI and BITE questionnaires showed a significant correlation within the AN patients group.

CONCLUSIONS

The results for female adolescent patients with AN indicate that there is a dysfunction of intra- and intercellular inflammatory pathways characterized by higher levels of pro-inflammatory parameters in plasma and a decrease in one of the controlling cytoplasmic-nuclear pathways implicated in their modulation (i.e. PPARγ) with, at this very early stage of the disease, no effect on oxidative stress markers plasma levels. Most notably, higher severity of illness (restrictive and purging behaviour) correlated with higher levels of inflammatory markers.

A systematic review of in vitro cytokine production in eating disorders

BACKGROUND

Eating disorders (EDs) have been associated with alterations in cytokine concentrations and production. This review examines whether in vitro cytokine production (i) is altered in people with EDs compared to healthy participants; and (ii) changes in response to treatment?

METHODS

Using PRISMA guidelines, we systematically reviewed articles reporting group comparisons or longitudinal assessments of spontaneous and/or stimulated cytokine production in vitro in people with EDs.

RESULTS

Twelve studies were included. Cross-sectional results were mixed in anorexia nervosa. Only one study measured cytokine production in bulimia nervosa. Two longitudinal studies showed that daily yoghurt consumption increases phytohemagglutinin-stimulated interferon-γ production in anorexia nervosa.

CONCLUSION

The mixed results could be accounted for by variations in experimental design. Our findings suggest that cytokine production could possibly be modulated through dietary interventions. However, due to the methodological heterogeneity and shortcomings of the included studies, it seems unreasonable to draw further conclusions.

Can improvement in hormonal and energy balance reverse cardiovascular risk factors in athletes with amenorrhea?

Female athletes display a high prevalence of hypothalamic amenorrhea as a result of energy imbalance. In these athletes with amenorrhea, decreased luteinizing hormone/follicule-stimulating hormone secretion leads to deficiency in endogenous estrogen. The severe estrogen deficiency in these athletes may increase cardiovascular risk similar to that in postmenopausal women. This review discusses the potential cardiovascular risk factors in athletes with amenorrhea as a result of hypoestrogenism, which include endothelial dysfunction and unfavorable lipid profiles. We also consider the potential to reverse the cardiovascular risk by restoring energy or hormonal imbalance along the reproductive axis in athletes with amenorrhea.

Brain-Behavior-Immune Interaction: Serum Cytokines and Growth Factors in Patients with Eating Disorders at Extremes of the Body Mass Index (BMI) Spectrum

Alterations of the immune system are known in eating disorders (EDs), however the importance of cytokine balance in this context has not been clarified. We compared cytokines and growth factors at opposite ends of BMI ranges, in 90 patients classified in relation to BMI, depressive and EDs comorbidities. Serum concentrations of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were determined by a biochip analyzer (Randox Labs). Differences were calculated through ANOVA. Possible predictors of higher cytokine levels were evaluated through regression analysis. IL-1α, IL-10, EGF, and IFN-γ were altered individuals with anorexia nervosa (AN) and binge eating disorder (BED). Night-eating was associated with IL-8 and EGF levels, IL-10 concentrations with post-dinner eating and negatively with sweet-eating, long fasting with higher IFN-γ levels. IL-2 increase was not linked to EDs, but to the interaction of depression and BMI. Altogether, for the first time, IL-1α, IL-10, EGF, and IFN-γ were shown to differ between AN and HCs, and between AN and individuals with obesity with or without BED. Only IL-2 was influenced by depression. Dysfunctional eating behaviors predicted abnormal concentrations of IL-10, EGF, IL-8 and IFN-γ.

Adipokines, cortisol and cytokine alterations in recent onset anorexia nervosa. A case-control study

INTRODUCTION

Psychological and neuroendocrine alterations are typical characteristics in anorexia nervosa patients. The role of adipokines and cytokines as mediators of body systems' adaptations to the patients' abnormal eating behavior is not well understood. The duration of disease seems to be a determinant of nutritional status and associated hormone changes. We aimed to assess whether alterations in adipokines, cytokines and cortisol do already exist in patients with a recent disease onset by means of a case-control study.

METHODS

Forty-one adolescent female patients on their first-episode and diagnosed with anorexia nervosa, were matched by age and socioeconomic status (SES) (1:1) with healthy girls. Leptin, soluble leptin receptor (sOB-R), adiponectin, cortisol, and the cytokines IL-1β, IL-2, IL-6 and TNF-α were examined.

RESULTS

The results showed reduced leptin and increased sOB-R and cortisol levels in AN patients. Adiponectin was also increased but opposite to the previous biomarkers did not correlate with BMI Z-score. Serum TNF-α and IL-2 showed significantly lower and higher values, respectively, in the AN patients than in the controls. Cortisol showed the strongest correlation with sOB-R (r=0.436; P=0.005).

CONCLUSIONS

Our study confirms previous findings on adipokine and cortisol alterations in AN patients, while overall cytokine results did not show a clear disruption in AN patients with short disease duration. The results highlight the need to disentangle the role of the sOB-R in the interactions between leptin and cortisol secretion.

Decline of Plasma Concentrations of Interleukin-18 in Severely Malnourished Patients with Anorexia Nervosa: Exploratory Analysis

Multiple studies on the dynamics of inflammatory cytokines in patients with anorexia nervosa (AN) have been published, although results are not consistent among reports. Thus the pathophysiologic roles of these cytokines are not clear. We performed an exploratory analysis that included (1) comparisons of plasma interleukin-18 (IL-18) concentrations between patients with AN (n = 21) and healthy controls (n = 39), and (2) correlations between body mass index (BMI) and IL-18 concentrations in both groups, exploring the relationship between malnourishment and IL-18. Plasma IL-18 levels were significantly decreased in patients with AN compared with controls. Plasma IL-18 levels correlated to BMI in controls, but not in patients with AN. These results suggest that a decline in plasma IL-18 levels in patients with AN is not only due to malnourishment, but other pathophysiologic changes as well. IL-18 has a role in the brain’s reaction to sadness and chronic stress. Therefore, decreased levels of IL-18 may commonly occur in patients with chronic AN.

A meta-analysis of cytokine concentrations in eating disorders

Cytokines are signalling molecules, which play an important role in both immune system function and brain development and function, and subsequently mental states and behaviour. Cytokines have been implicated in eating disorders (EDs) due to their role in psychological health, body weight and appetite regulation. This meta-analysis examined cross-sectional and longitudinal studies measuring concentrations of cytokines in individuals with EDs. Using PRISMA guidelines, we systematically reviewed relevant articles in PubMed, Web of Science, and MEDLINE. Random-effects meta-analyses were conducted for interleukin (IL)-1β, IL-6, transforming growth factor (TGF)-β, and tumor necrosis factor (TNF)-α, independently, firstly with all EDs combined and then stratified by ED diagnosis. Twenty-five studies were included: serum/plasma cytokine concentrations were measured in people with anorexia nervosa (AN) in 23 studies and bulimia nervosa (BN) in 4 studies. TNF-α and IL-6 were elevated in ED participants compared to healthy controls (HCs). Specifically, this pattern was seen only when comparing AN participants to HCs. Concentrations of these cytokines did not differ between people with BN and HCs. IL-1β and TGF-β did not differ between HCs and any ED group. Therefore, AN seems to be associated with elevated concentrations of TNF-α and IL-6. Considering the role of cytokines in appetite, mood regulation, and anxiety, these pro-inflammatory cytokines could be a potential future drug target to help people with AN, not only with weight gain, but also with various coexisting psychological problems. Future studies should consider confounding factors that affect cytokine concentrations and report ED-relevant clinical characteristics.

PET radioligand binding to translocator protein (TSPO) is increased in unmedicated depressed subjects

BACKGROUND

Inflammation is associated with major depressive disorder (MDD). Translocator protein 18 kDa (TSPO), a putative biomarker of neuroinflammation, is quantified using positron emission tomography (PET) and 11C-PBR28, a TSPO tracer. We sought to (1) investigate TSPO binding in MDD subjects currently experiencing a major depressive episode, (2) investigate the effects of antidepressants on TSPO binding, and (3) determine the relationship of peripheral and central inflammatory markers to cerebral TSPO binding. Twenty-eight depressed MDD subjects (unmedicated (n = 12) or medicated (n = 16)) and 20 healthy controls (HC) underwent PET imaging using 11C-PBR28. Total distribution volume (VT, proportional to Bmax/Kd) was measured and corrected with the free fraction in plasma (fp). The subgenual prefrontal cortex (sgPFC) and anterior cingulate cortex (ACC) were the primary regions of interest. Peripheral blood samples and cerebrospinal fluid were analyzed to investigate the relationship between TSPO binding and peripheral and central inflammatory markers, including interleukins and neurotrophic factors previously linked to depression.

RESULTS

TSPO binding was higher in MDD versus HC in the sgPFC (Cohen's d = 0.64, p = .038, 95% CI 0.04-1.24) and ACC (d = 0.60, p = .049, 95% CI 0.001-1.21), though these comparisons missed the corrected threshold for statistical significance (α = .025). Exploratory analyses demonstrated that unmedicated MDD subjects had the highest level of TSPO binding, followed by medicated MDD subjects, who did not differ from HC. TSPO binding correlated with interleukin-5 in cerebrospinal fluid but with no other central inflammatory markers.

CONCLUSIONS

This study found a trend towards increased TSPO binding in the brains of MDD subjects, and post hoc analysis extended these findings by demonstrating that this abnormality is significant in unmedicated (but not medicated) MDD subjects.

Immune disorders in anorexia

Anorexia nervosa is a disease involving eating disorders. It mainly affects young people, especially teenage women. The disease is often latent and occurs in many sub-clinical and partial forms. Approximately from 0.3% to 1% of the population suffers from anorexia. It has been shown that patients with anorexia develop neurotransmitter-related disorders, leading to uncontrolled changes in the immune and endocrine systems. Interactions between cytokines, neuropeptides, and neurotransmitters play an important role in disease development. Significant malnutrition induces disorders and alterations in T-cell populations. The cellular response in patients with anorexia nervosa has been shown to be normal, although opinions on this issue are controversial. Laboratory studies on neutrophils in anorexia patients showed decreased adhesion and reduced bactericidal and cell activities. Despite such unfavourable results, patients with anorexia are resistant to infections, which are very rare in this group. Glutamine improves the performance of the human immune system. The administration of glutamine to anorexia patients, as a supplement to parenteral nutrition, has resulted in significant improvements in immune system parameters. The results of previous studies on the causes and risk factors in the development of anorexia nervosa are still ambiguous. One can hope that the differences and similarities between patients with anorexia nervosa and those with other forms of protein-calorie malnutrition may be helpful in determining the relationship between nutritional status and body defences and susceptibility to infection, and can help to broaden the knowledge about the aetiopathogenesis of anorexia nervosa.

Hypothalamic expression of inflammatory mediators in an animal model of binge eating

Binge eating episodes are characterized by uncontrollable, distressing eating of a large amount of highly palatable food and represent a central feature of bingeing related eating disorders. Research suggests that inflammation plays a role in the onset and maintenance of eating-related maladaptive behavior. Markers of inflammation can be selectively altered in discrete brain regions where they can directly or indirectly regulate food intake. In the present study, we measured expression levels of different components of cytokine systems (IL-1, IL-6, IL-18, TNF-α and IFN-ɣ) and related molecules (iNOS and COX2) in the preoptic and anterior-tuberal parts of the hypothalamus of a validated animal model of binge eating. In this animal model, based on the exposure to both food restriction and frustration stress, binge-like eating behavior for highly palatable food is not shown when animals are exposed to the frustration stress during the estrus phase. We found a characteristic down-regulation of the IL-18/IL-18 receptor system (with increased expression of the inhibitor of the pro-inflammatory cytokine IL-18, IL-18BP, together with a decreased expression of the binding chain of the IL-18 receptor) and a three-fold increase in the expression of iNOS specifically in the anterior-tuberal region of the hypothalamus of animals that develop a binge-like eating behavior. Differently, when food restricted animals were stressed during the estrus phase, IL-18 expression increased, while iNOS expression was not significantly affected. Considering the role of this region of the hypothalamus in controlling feeding related behavior, this can be relevant in eating disorders and obesity. Our data suggest that by targeting centrally selected inflammatory markers, we may prevent that disordered eating turns into a full blown eating disorder.

Interleukin-7 Plasma Levels in Human Differentiate Anorexia Nervosa, Constitutional Thinness and Healthy Obesity

Introduction

Interleukin-7 (IL-7) is a cytokine involved in energy homeostasis as demonstrated in rodents. Anorexia nervosa is characterized by restrained eating behavior despite adaptive orexigenic regulation profile including high ghrelin plasma levels. Constitutional thinness is a physiological condition of resistance to weight gain with physiological anorexigenic profile including high Peptide YY plasma level. Healthy obesity can be considered as a physiological state of resistance to weight loss with opposite appetite regulating profile to constitutional thinness including low Peptide YY plasma level. No studies in IL-7 are yet available in those populations. Therefore we evaluated circadian plasma levels of IL-7 in anorexia nervosa compared to constitutional thinness, healthy obese and control females.

Materials and Methods

10 restrictive-type anorexia nervosa women, 5 bingeing/purging anorexia nervosa woman, 5 recovered restrictive anorexia nervosa women, 4 bulimic females, 10 constitutional thinness women, 7 healthy obese females, and 10 normal weight women controls were enrolled in this cross-sectional study, performed in endocrinology unit and academic laboratory. Twelve-point circadian profiles of plasma IL-7 levels were measured in each subject.

Results

24h mean IL-7 plasma levels (pg/ml, mean±SEM) were decreased in restrictive-type anorexia nervosa (123.4±14.4, p<0.0037), bingeing/purging anorexia nervosa (24.2±5.6, p<0.001), recovered restrictive anorexia nervosa (64.2±16.1, p = 0.01) and healthy obese patients (51±3.2, p<0.001) compared to controls (187.7±28.6). Bulimic patients (197.4±42.7) and constitutional thinness patients (264.3±35.8) were similar to controls.

Conclusions

Low IL-7 is part of the adaptive profile in restrictive-type anorexia nervosa, confirming its difference with constitutional thinness. Healthy obesity, with low IL-7, is once again in mirror image of constitutional thinness with normal high IL-7.

Inflammatory cytokines and anorexia nervosa: A meta-analysis of cross-sectional and longitudinal studies

OBJECTIVE

Although inflammation is increasingly implicated in psychiatric disorders, less is known about its role in anorexia nervosa (AN), an illness with low body mass index (BMI).

METHODS

We performed a systematic PubMed literature search until 12/31/2013 and meta-analyzed cross-sectional and longitudinal studies comparing circulating pro- and anti-inflammatory cytokines between patients with anorexia nervosa (AN) and healthy controls (HCs) (1) before and (2) after weight gain, and (3) within AN patients before and after weight gain. Standardized mean differences (SMDs)± 95% confidence intervals (CIs) for results from ≥ 2 studies were calculated.

RESULTS

Of 999 initial hits, 22 studies with 924 participants (AN=512, HCs=412) were eligible. Compared to HCs, tumor necrosis factor (TNF)-alpha (SMD=0.35, 95%CI=0.09-0.61, p=0.008), interleukin (IL)1-beta (SMD=0.51, 95%CI=0.18-0.84, p=0.003), IL-6 (SMD=0.43, 95%CI=0.11-0.76, p=0.009), and TNF-receptor-II (SMD=0.42, 95%CI:0.07-0.78, p=0.02) were significantly elevated in AN, while C-reactive protein (SMD=-0.53, 95%CI=-.77, -0.28, p<0.0001) and IL-6 receptor (SMD=-0.85, 95%CI=-1.33, -0.36, p=0.0006) were significantly decreased. No differences were found for TNF-receptor I and TGF-β. Across a subset of eight longitudinal studies (AN=152, HCs=129), significant weight gain (baseline BMI=15.4 ± 1.5, endpoint BMI=18.2 ± 1.6, p<0.0001) was not associated with significant changes in TNF-α, IL-6 and IL1-β. However, after weight gain, IL-6 was not different anymore compared to HCs (SMD=0.06, 95%CI=-0.32, 0.45, p=0.75). In meta-regression, shorter illness duration (p=0.0008), but not younger age (p=0.71) significantly moderated greater IL-6 levels.

CONCLUSION

Despite abnormally low BMI, AN seems to be associated with increased inflammatory cytokines. Whether specific elevated cytokines represent trait or state markers of AN, and whether they could be treatment targets requires further study.

The expression of cytokines and chemokines in the blood of patients with severe weight loss from anorexia nervosa: an exploratory study

Anorexia nervosa (AN) is a serious, potentially life-threatening disorder characterized by severe weight loss, dysregulated eating, and often excessive exercise. While psychiatric illnesses such as depression are associated with increased levels of pro-inflammatory mediators, evidence for such disturbances in patients with AN has been less clear. In an exploratory study of possible disturbances in immune responses in AN, we assayed a panel of cytokines and chemokines in the blood of patients undergoing inpatient treatment, testing the hypothesis that metabolic disturbances in this disease would lead to a pattern of immune disturbances distinct from that of other psychiatric diseases. For this purpose, we evaluated patients by the Beck Depression Inventory-II (BDI-II) and the Eating Disorders Examination-Questionnaire and assessed cytokines and chemokines by enzyme-linked immunosorbent assays. Patients reported a moderate level of depression (mean BDI-II = 22.6) but exhibited few immunologic abnormalities of the kind associated with major depressive disorder [e.g., increased interleukin (IL)-6]; RANTES showed the most frequent elevations and was increased in 4 of the patients studied. Together, these findings suggest that features of AN such as loss of adipose tissue and excessive exercise may attenuate cytokine production and thus modulate the experience of illness that impacts on core features of disease.

Elevated levels of exhaled nitric oxide in patients with anorexia nervosa

BACKGROUND

Nitric oxide (NO) is involved in eating behavior and inflammatory response. Moreover, there is evidence that NO production is altered in patients with anorexia nervosa (AN).

AIM

To assess whether the overproduction of NO in AN can affect NO level in exhaled air.

MATERIALS AND METHODS

Exhaled NO level was studied in 23 girls with AN and compared with that of healthy age- and gender-matched nonatopic controls.

RESULTS

Exhaled NO levels were significantly higher in girls with AN compared with healthy age-matched controls.

CONCLUSIONS

It appears that anorexia nervosa was accompanied by a higher level of exhaled NO, likely resulting from a systemic increase in NO production because of the severe catabolic state.

Circulating interleukin 6 and soluble forms of its receptors in relation to resting energy expenditure in women with anorexia nervosa

CONTEXT

Anorexia nervosa (AN) is an eating disorder, resulting in sustained low weight and marked decrease in fat mass. Interleukin 6 (IL-6) may play a role in appetite, energy expenditure and body weight control. IL-6 acts through binding with membrane receptor (IL-6R) and activates glycoprotein 130 (gp130) signalling. Both IL-6R and gp130 are present in the blood in the soluble forms (sIL-6R and sgp130 respectively). sIL-6R sensitizes cells towards IL-6, whereas sgp130 inhibits gp130 signalling.

OBJECTIVE

To estimate circulating IL-6/sIL-6R/sgp130 system and its relationships with body weight and resting energy expenditure (REE) in AN women.

PATIENTS

We examined 19 women with AN and 27 healthy normal-weight female controls.

MEASUREMENTS

Indirect calorimetry and the measurement of serum IL-6, sIL-6R and sgp130 concentrations were performed in all the subjects.

RESULTS

REE was decreased in AN women (P < 0·001). Serum IL-6 was higher in AN women in comparison with control group (P = 0·005). Serum sIL-6R was lower (P = 0·009) and serum sgp130 was higher (P = 0·004) in AN women in comparison with controls. IL-6 and sIL-6R were related to REE in the entire study population (r = -0·54, P < 0·001 and r = 0·48, P = 0·001 respectively) and in AN group (r = -0·54, P = 0·024 and r = 0·60, P = 0·011 respectively).

CONCLUSIONS

Increased IL-6 in AN seems to be compensated by the changes in sIL-6R and sgp130, which are directed towards inhibition of IL-6 action. The balance between these factors might play a role in the regulation of energy expenditure in AN.

Tumour necrosis factor alpha and oxidative stress as maintaining factors in the evolution of anorexia nervosa

OBJECTIVE

Aim of the study was to evaluate tumour necrosis factor α (TNF-α) axis and oxidative status in patients with anorexia nervosa (AN) seeking a possible correlation with both nutritional status and evolution of the disease.

SUBJECTS AND METHODS

Thirty-nine consecutive women with AN and an age-matched healthy control group were studied. Patients were 26±9 yr, with a body mass index (BMI) of 13.9±2 kg/m(2). TNF-α, its receptors TNF-R55 and TNF-R75, and oxidative status markers (selenium, ascorbic/ dehydroascorbic acid, retinol, α-tocopherol, selenium-dependent gluthatione peroxidase, reduced/oxidated gluthatione) were measured. A correlation with both nutritional indexes (body weight, BMI, albumin, prealbumin, transferrin, lymphocyte count) and disease duration was investigated. Pearson's correlation and unpaired Student's t-test were used to compare patients and controls.

RESULTS

TNF-α and oxidative status markers were significantly higher in patients than controls and TNF-α was directly related to dehydroascorbic acid (p<0.05). Both TNF-R55 and TNF-R75 were higher in patients with duration of disease longer than one year as compared to controls and patients with shorter duration. Receptors inversely correlated with BMI (p<0.05 and p<0.01) and directly with disease duration (p<0.05). Inverse correlation between disease duration and BMI was present (p<0.01).

CONCLUSIONS

The study showed activation of TNF-α axis and oxidative stress in AN patients, as well as correlation between the two systems. Due to the correlation between TNF receptors and both BMI and disease duration, a possible role of pro-inflammatory cytokines in the evolution of the eating disorder is suggested.

Association between inflammatory and obesity markers in a Swiss population-based sample (CoLaus Study)

OBJECTIVE

To assess the associations between obesity markers (BMI, waist circumference and %body fat) and inflammatory markers (interleukin-1β (IL-1β); interleukin-6 (IL-6); tumor necrosis factor-α (TNF-α) and high-sensitivity C-reactive protein (hs-CRP)).

METHODS

Population sample of 2,884 men and 3,201 women aged 35-75 years. Associations were assessed using ridge regression adjusting for age, leisure-time physical activity, and smoking.

RESULTS

No differences were found in IL-1β levels between participants with increased obesity markers and healthy counterparts; multivariate regression showed %body fat to be negatively associated with IL-1β. Participants with high %body fat or abdominal obesity had higher IL-6 levels, but no independent association between IL-6 levels and obesity markers was found on multivariate regression. Participants with abdominal obesity had higher TNF-α levels, and positive associations were found between TNF-α levels and waist circumference in men and between TNF-α levels and BMI in women. Obese participants had higher hs-CRP levels, and these differences persisted after multivariate adjustment; similarly, positive associations were found between hs-CRP levels and all obesity markers studied.

CONCLUSION

Obesity markers are differentially associated with cytokine levels. %Body fat is negatively associated with IL-1β; BMI (in women) and waist circumference (in men) are associated with TNF-α; all obesity markers are positively associated with hs-CRP.

Hepcidin, interleukin-6 and hematological iron markers in males before and after heart surgery

Anemia of inflammation in patients with acute or chronic acute-phase activation is a common clinical problem. Hepcidin is a peptide shown to be the principal regulator of the absorption and systemic distribution of iron. Main inducers of hepcidin are iron overload, hypoxia and inflammation, where the latter has been linked to hepcidin via increased interleukin-6 (IL-6). This article addresses the impact and time course of postoperative acute-phase reaction in humans following heart surgery on prohepcidin, hepcidin, hematological markers and IL-6 concentrations. Serum concentrations of prohepcidin, hepcidin, IL-6 and hematological iron parameters were studied in five male patients without infection before and after heart surgery. This study, which is the first to report the impact on serum hepcidin and serum prohepcidin concentrations in patients following surgery, clearly demonstrates the induction of hypoferremia due to the postoperative acute-phase reaction. Significant changes were seen for serum iron concentration, transferrin saturation, total iron binding capacity and hemoglobin concentration. A significant increase in ferritin concentration was seen 96-144 h postoperatively. Additionally, there were significant alterations in both serum hepcidin after 96-144 h and serum prohepcidin after 48 h compared with preoperative values. Serum prohepcidin decreased, whereas serum hepcidin increased. In conclusion, changes in serum prohepcidin were followed by an increase in serum hepcidin. This speaks in favor of a chain of action where proteolytic trimming of serum prohepcidin results in increased serum hepcidin. However, hypoferremia appeared prior to the changes in serum prohepcidin and serum hepcidin.

The immune system in extreme longevity

Recent observations indicate that immunosenescence is not accompanied by an unavoidable and progressive deterioration of the immune function, but is rather the result of a remodeling where some functions are reduced, others remain unchanged or even increased. In addition, it appears that the ancestral/innate compartment of the immune system is relatively preserved during aging in comparison to the more recent and sophisticated adaptive compartment that exhibit more profound modifications. The T-cell branch displays an age-dependent decline of the absolute number of total T-cells (CD3+), involving both CD4+ and CD8+ subsets, accompanied by an increase of NK cells with well-preserved cytotoxic function and by a reduction of B-cells. One of the main characteristics of the immune system during aging is a progressive, age-dependent decline of the virgin T-cells (CD95-), which is particularly profound at the level of the CD8+ subpopulation of the oldest old subjects. The progressive exhaustion of this important T-cell subpopulation dedicated primarily to the defense against new antigenic challenges (viral, neoplastic, bacterial ones), could be a consequence of both the thymic involution and the lifelong chronic antigenic stimulation. The immune function of the elderly, is therefore weakened by the exhaustion of CD95- virgin cells that are replaced by large clonal expansions of CD28- T-cells. The origin of CD28- cells has not been completely clarified yet, but it is assumed that they represent cells in the phase of replicative senescence characterized by shortening telomers and reduced proliferative capacity. A major characteristic of the immune system during aging is the up-regulation of the inflammatory responses which appears to be detrimental for longevity. In this regard, we have recently observed a progressive age-dependent increase of type 1(IL-2, IFN-gamma, TNF-alpha) and type 2 (IL-4, IL-6, IL-10) positive CD8+ T-cells; in particular, type 1 cytokine-positive cells significantly increased, with age, in all CD8+ subsets particularly among effector/cytotoxic and memory cells. A major force able to drive a chronic pro-inflammatory state during aging may be represented by persistent viral infections by EBV and CMV. Therefore, we have determined the frequency and the absolute number of viral antigen-specific CD8+ T-cells in subjects older than 85 years, who were serologically positive for CMV or EBV. In the majority of these subjects we detected the presence of T lymphocytes positive for epitopes of CMV or EBV. In all subjects the absolute number of CMV-positive CD8+ cells outnumbered that of EBV-positive ones. In addition, the majority of CMV+ T cells were included within the CD28- subpopulation, while EBV+ T cells belonged mainly to the CD28+ subset. These data indicate that the chronic antigenic stimulation induced by persistent viral infections during aging bring about important modifications among CD8+ subsets, which are particularly evident in the presence of CMV persistence. The age-dependent expansions of CD8+CD28- T-cells, mostly positive for pro-inflammatory cytokines and including the majority of CMV-epitope-specific cells, underlines the importance of chronic antigenic stimulation in the pathogenesis of the main immunological alterations of aging and may favour the appearance of several pathologies (arteriosclerosis, dementia, osteoporosis, cancer) all of which share an inflammatory pathogenesis.

Capturing the onset of the common cold and its effects on iron absorption

Hypoferremia is a well-known response to infections and inflammatory disorders. It seems to be managed by the key mediator of iron kinetics, hepcidin. There are several studies on induced-acute phase reactions. However, to our best knowledge there are no previous published reports on the outbreak of a common cold and its initial effect on iron kinetics. The objective of this case report is to describe such an observation. From an apparently healthy state in the morning we observed, in a 28-year-old male, every hour for 6 h the outbreak of a common cold and the modulations in the levels of serum iron (S-Fe) and interleukin-6 (IL-6). Despite a 100 mg oral iron loading there was a substantial reduction in S-Fe, which seemed to precede the IL-6 peak. Interestingly, this observed succession is in conflict with the proposed infection chain of order in which IL-6 stimulates hepcidin induction.

Uncoupling of cardiovascular risk markers in adolescent girls with anorexia nervosa

OBJECTIVE

Cardiovascular (CV) risk begins in childhood, and low body weight should result in a favorable risk profile. However, adolescents with anorexia nervosa (AN) have alterations in many hormonal factors that mediate CV risk. We hypothesized that in AN, growth hormone (GH) resistance and hypercortisolemia would increase CV risk through effects on pro-inflammatory cytokines and lipid status despite low weight.

STUDY DESIGN

We examined CV risk markers (high sensitivity C-reactive protein [hsCRP], interleukin-6 [IL-6], apolipoprotein-B [Apo-B], and lipid profile) in 23 subjects with AN and in 20 control subjects 12 to 18 years of age, in whom GH, cortisol, leptin, and triiodothyronine (T3) had been previously determined.

RESULTS

Subjects with AN had higher Apo-B (P < .0001), IL-6 (P = .03), Apo-B/high-density lipoprotien (HDL) (P = .01), and Apo-B/low-density lipoprotein (LDL) (P < .0001) and lower hsCRP (P = .01) than controls. Triglycerides were lower and HDL higher in subjects with AN. IGF-I predicted hsCRP in controls but not in AN. Log hsCRP correlated positively with GH and inversely with leptin. On regression modeling, the most significant predictor of log hsCRP was leptin; T3 predicted log IL-6, log Apo-B, log Apo-B/HDL, and Apo-B/LDL; and cortisol independently predicted log Apo-B. IL-6 decreased with weight gain.

CONCLUSION

CV risk markers are uncoupled in AN, with increased Apo-B and IL-6 and decreased hsCRP, related to hormonal alterations. IL-6 normalizes with weight gain.

Increased cortisol responsivity to adrenocorticotropic hormone and low plasma levels of interleukin-1 receptor antagonist in women with functional hypothalamic amenorrhea

OBJECTIVE

To assess the hypothalamic-pituitary-adrenal (HPA) axis at all levels, to determine the origin of the previously reported hypercortisolism in patients with functional hypothalamic amenorrhea. A secondary aim was to evaluate factors outside the central nervous system which are known to affect the HPA axis, i.e., circulating levels of interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra), and fat mass-adjusted leptin levels, in patients with functional hypothalamic amenorrhea and healthy controls.

DESIGN

Cross-sectional study.

SETTING

Umeå University Hospital, Umeå, Sweden.

PATIENTS

Fifteen subjects with hypothalamic amenorrhea, and 14 age- and weight-matched controls.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

We collected blood samples four times during a 24-hour interval for analysis of cortisol, leptin, IL-1Ra, and IL-6 levels. We performed a low-dose oral dexamethasone test and a low-dose ACTH test. We measured body-fat percentage using a dual-energy X-ray absorptiometer.

RESULTS

Patients with hypothalamic amenorrhea had increased diurnal cortisol levels (P<.001). The cortisol response to intravenous low-dose ACTH was increased in functional hypothalamic amenorrhea patients compared to control subjects (P<.01), but they had similar rates of dexamethasone suppression. Patients with hypothalamic amenorrhea also had decreased diurnal leptin (P<.05), and decreased diurnal IL-1Ra levels (P<.05), compared to controls. Body-fat percentage was the main predictor of leptin levels.

CONCLUSION

The present study suggests novel links for the development of functional hypothalamic amenorrhea, including increased adrenal responsiveness and impairments in proinflammatory cytokine pathways.

Adipose tissue resistin levels in patients with anorexia nervosa

OBJECTIVE

Resistin is a specific fat-derived hormone that affects fuel homeostasis and insulin action in rodents. However, its role in human physiology and pathophysiologic conditions, such as malnutrition, remains uncertain.

METHODS

To enhance understanding of the role of resistin in the pathophysiology of anorexia nervosa (AN), we measured plasma resistin levels in 13 women with a restrictive type of AN and in 16 healthy age-matched women (control). Further, we measured resistin levels in the subcutaneous adipose tissue of eight women from the AN group and eight women from the control group with an in vivo microdialysis technique (CMA/107 pump, CMA/60 catheters, CMA Microdialysis AB, Solna, Sweden).

RESULTS

Body mass index, percentage of body fat, fasting plasma leptin and insulin, and homeostasis model assessment index for insulin resistance were severely decreased in patients with AN compared with the control group. Plasma resistin levels were significantly decreased in patients with AN (P < 0.05), whereas subcutaneous adipose tissue resistin levels were significantly increased in patients with AN compared with the control group (P < 0.05). In both groups, plasma resistin levels showed no significant relation to resistin in dialysate, percentage of body fat, body mass index, homeostasis model assessment index for insulin resistance, and fasting plasma leptin levels.

CONCLUSION

We demonstrated that AN is associated with decreased plasma resistin levels and increased resistin levels in extracellular space of the abdominal adipose tissue. Plasma resistin levels in patients with AN or in healthy normal-weight women were not directly related to body mass index, percentage of body fat, plasma leptin levels, and insulin sensitivity.

Anorexia nervosa and osteoporosis

Anorexia nervosa (AN), a condition of severe undernutrition, is associated with low bone mineral density (BMD) in adults and adolescents. Whereas adult women with AN have an uncoupling of bone turnover markers with increased bone resorption and decreased bone formation markers, adolescents with AN have decreased bone turnover overall. Possible contributors to low BMD in AN include hypoestrogenism and hypoandrogenism, undernutrition with decreased lean body mass, and hypercortisolemia. IGF-I, a known bone trophic factor, is reduced despite elevated growth hormone (GH) levels, leading to an acquired GH resistant state. Elevated ghrelin and peptide YY levels may also contribute to impaired bone metabolism. Weight recovery is associated with recovery of BMD but this is often partial, and long-term and sustained weight recovery may be necessary before significant improvements are observed. Anti-resorptive therapies have been studied in AN with conflicting results. Oral estrogen does not increase BMD or prevent bone loss in AN. The combination of bone anabolic and anti-resorptive therapy (rhIGF-I with oral estrogen), however, did result in a significant increase in BMD in a study of adult women with AN. A better understanding of the pathophysiology of low BMD in AN, and development of effective therapeutic strategies is critical. This is particularly so for adolescents, who are in the process of accruing peak bone mass, and in whom a failure to attain peak bone mass may occur in AN in addition to loss of established bone.

Leptin and cytokines levels in children with failure to thrive

BACKGROUND

The majority of cases of failure to thrive (FTT) are non-organic. Many of these patients present with significant decreased caloric intake. It appears as if the appetite regulation center in the hypothalamus is not attuned to the calorie requirements of the infant.

OBJECTIVE

Our hypothesis was that some cases of non-organic FTT might be caused by abnormalities in hunger/satiety control secondary to neuroendocrine or cytokine imbalance. The aim of this study was to investigate which hormonal/cytokine profiles could be assigned to a defined category of FTT, namely organic, psychosocial and idiopathic subgroups.

STUDY DESIGN

34 patients were enrolled and 32 completed the study (12 controls, 12 idiopathic FTT, 5 organic FTT, and 3 psychosocial FTT). Each child was assessed by a pediatric gastroenterologist, dietician, and social worker and underwent appropriate laboratory investigation during which leptin, IL1, IL6 and TNF-alpha levels were determined. The Mann-Whitney U test was used to compare the groups.

RESULTS

IL6 was the only cytokine that showed significant differences between FTT patients (4.06 +/- 6.3 pg/ml) and normal controls (0.0 pg/ml (p = 0.028). Leptin values were significantly higher in the normal control group (1632 +/- 483 pg/ml) as compared to FTT patients (685 +/- 687 pg/ml) (p = 0.001).

CONCLUSIONS

Our results indicate that leptin does not play a role in the pathogenesis of anorexia in children with FTT. It is however, possible that IL6 may be an important factor in the etiology of anorexia in patients with FTT.

Nutritional status in the neuroendocrine control of growth hormone secretion: the model of anorexia nervosa

Growth hormone (GH) plays a key role not only in the promotion of linear growth but also in the regulation of intermediary metabolism, body composition, and energy expenditure. On the whole, the hormone appears to direct fuel metabolism towards the preferential oxidation of lipids instead of glucose and proteins, and to convey the energy derived from metabolic processes towards the synthesis of proteins. On the other hand, body energy stores and circulating energetic substrates take an important part in the regulation of somatotropin release. Finally, central and peripheral peptides participating in the control of food intake and energy expenditure (neuropeptide Y, leptin, and ghrelin) are also involved in the regulation of GH secretion. Altogether, nutritional status has to be regarded as a major determinant in the regulation of the somatotropin-somatomedin axis in animals and humans. In these latter, overweight is associated with marked impairment of spontaneous and stimulated GH release, while acute dietary restriction and chronic undernutrition induce an amplification of spontaneous secretion together with a clear-cut decrease in insulin-like growth factor I (IGF-I) plasma levels. Thus, over- and undernutrition represent two conditions connoted by GH hypersensitivity and GH resistance, respectively. Anorexia nervosa (AN) is a psychiatric disorder characterized by peculiar changes of the GH-IGF-I axis. In these patients, low circulating IGF-I levels are associated with enhanced GH production rate, highly disordered mode of somatotropin release, and variability of GH responsiveness to different pharmacological challenges. These abnormalities are likely due not only to the lack of negative IGF-I feedback, but also to a primary hypothalamic alteration with increased frequency of growth hormone releasing hormone discharges and decreased somatostatinergic tone. Given the reversal of the above alterations following weight recovery, these abnormalities can be seen as secondary, and possibly adaptive, to nutritional deprivation. The model of AN may provide important insights into the pathophysiology of GH secretion, in particular as regards the mechanisms whereby nutritional status effects its regulation.

Involvement of cytokines in eating disorders: a critical review of the human literature

A number of findings from clinical and animal studies indicate that pro-inflammatory cytokines may play roles in eating disorders. The measurement of pro-inflammatory cytokines (IL-1, IL-6, TNFalpha), which are known to decrease food intake, provides highly variable data from which firm conclusions cannot be drawn. In most of the longitudinal studies where pro-inflammatory cytokines have been shown to be impaired in anorexia or bulimia nervosa, a return to normal values was observed after renutrition. However these findings do not exclude the possibility that pro-inflammatory cytokines might be overproduced in specific brain areas and act locally without concomitantly increased serum or immune production. It was also pointed out that the production of the major type-1 cytokines (especially IL-2) was depressed in anorexia nervosa. It remains unclear whether this is due to undernutrition or to a specific underlying cause common to eating disorders. The impaired cytokine profile observed in eating disorders could be related to several factors including impaired nutrition, psychopathological and neuroendocrine factors. More particular attention should be devoted to the deregulation of the anti/pro-inflammatory balance. Deregulation of the cytokine network may be responsible for medical complications in eating disorder patients who are afflicted with chronic underweight.

The role of transsignalling via the agonistic soluble IL-6 receptor in human diseases

The activation of cells that do not express the membrane bound interleukin-6 6 receptor (IL-6R) by IL-6 and the soluble IL-6 receptor (sIL-6R) is termed transsignalling. Transsignalling may be an pathogenetic factor in human diseases as diverse as multiple myeloma (MM), Castleman's disease, prostate carcinoma, Crohn's disease, systemic sclerosis, Still's disease, osteoporosis and cardiovascular diseases. IL-6 and sIL-6R may directly or indirectly enhance their own production on endothelial or bone marrow stromal cells. Positive feedback autocrine loops thus created in affected organs may either cause or maintain disease progression. In autoimmune or vasculitic disease, the ability of the IL-6/sIL-6R complex to inhibit apoptosis of autoreactive T-cells may be central to the development of tissue specific autoimmunity. The anti-apoptotic effect of the IL-6/sIL-6R complex may be involved in tumour genesis and resistance to chemotherapy. Only in rare cases, where counterregulation has failed, there is a notable systemic effect of IL-6/sIL-6R. Appropriate animal models are necessary to establish the pathogenetic role of the IL-6/sIL-6R complex. A specific treatment option for diseases influenced by the sIL-6R could be based on gp130-Fc, a soluble gp130 (sgp130) linked to the Fc-fragment of IgG1. gp130-Fc has shown efficacy in vivo in animal models of Crohn's disease.