The antidepressant fluoxetine acts on energy balance and leptin sensitivity via BDNF

Leptin and Brain Derived Neurotrophic Factor (BDNF) pathways are critical players in body weight homeostasis. Noninvasive treatments like environmental stimulation are able to increase response to leptin and induce BDNF expression in the brain. Emerging evidences point to the antidepressant selective serotonin reuptake inhibitor Fluoxetine (FLX) as a drug with effects similar to environmental stimulation. FLX is known to impact on body weight, with mechanisms yet to be elucidated. We herein asked whether FLX affects energy balance, the leptin system and BDNF function. Adult lean male mice chronically treated with FLX showed reduced weight gain, higher energy expenditure, increased sensitivity to acute leptin, increased hypothalamic BDNF expression, associated to changes in white adipose tissue expression typical of "brownization". In the Ntrk2tm1Ddg/J model, carrying a mutation in the BDNF receptor Tyrosine kinase B (TrkB), these effects are partially or totally reversed. Wild type obese mice treated with FLX showed reduced weight gain, increased energy output, and differently from untreated obese mice, a preserved acute response to leptin in terms of activation of the intracellular leptin transducer STAT3. In conclusion, FLX impacts on energy balance and induces leptin sensitivity and an intact TrkB function is required for these effects to take place

Liver and White/Brown Fat Dystrophy Associates with Gut Microbiota and Metabolomic Alterations in 3xTg Alzheimer's Disease Mouse Model

Metabolic impairments and liver and adipose depots alterations were reported in subjects with Alzheimer's disease (AD), highlighting the role of the liver-adipose-tissue-brain axis in AD pathophysiology. The gut microbiota might play a modulating role. We investigated the alterations to the liver and white/brown adipose tissues (W/BAT) and their relationships with serum and gut metabolites and gut bacteria in a 3xTg mouse model during AD onset (adulthood) and progression (aging) and the impact of high-fat diet (HFD) and intranasal insulin (INI). Glucose metabolism (18FDG-PET), tissue radiodensity (CT), liver and W/BAT histology, BAT-thermogenic markers were analyzed. 16S-RNA sequencing and mass-spectrometry were performed in adult (8 months) and aged (14 months) 3xTg-AD mice with a high-fat or control diet. Generalized and HFD resistant deficiency of lipid accumulation in both liver and W/BAT, hypermetabolism in WAT (adulthood) and BAT (aging), abnormal cytokine-hormone profiles, and liver inflammation were observed in 3xTg mice; INI could antagonize all these alterations. Specific gut microbiota-metabolome profiles correlated with a significant disruption of the gut-microbiota-liver-adipose axis in AD mice. In conclusion, fat dystrophy in liver and adipose depots contributes to AD progression, and associates with altered profiles of the gut microbiota, which candidates as an appealing early target for preventive intervention.This study was conducted within the JPI-HDHL-INTIMIC Knowledge Platform of Food, Diet, Intestinal Microbiomics, and Human Health (sub-project no. KP-778 MISVILUPPO, Italian Ministry of Agricultural, Food and Forestry Policies, Ministry Decree 23092/7303/19), and the JPI-HDHL-INTIMIC Joint Transnational Research program (project no. INTIMIC-085 GUTMOM, Italian Ministry of Education, University and Research, Ministry Decree no. 946/2019). The funders had no role in study design, data collection and analysis, or preparation of the manuscript. Projects supported by the Joint Action “European Joint Programming Initiative: A Healthy Diet for a Healthy Life (JPI HDHL)” are funded by the respective national/regional funding organisations: Fund for Scientific Research (FRS—FNRS, Belgium); Research Foundation—Flanders (FWO, Belgium); INSERM Institut National de la Santé et de la Recherche Médicale (France); Federal Ministry of Food and Agriculture (BMEL) represented by Federal Office for Agriculture and Food (BLE, Germany); Ministry of Education, University and Research (MIUR), Ministry of agricultural, food, and forestry policies (MiPAAF), National Institute of Health (ISS) on behalf of the Ministry of Health (Italy); the National Institute of Health Carlos III (Spain); The Netherlands Organisation for Health Research and Development (ZonMw, The Netherlands), Austrian Research Promotion Agency (FFG) on behalf of the Austrian Federal Ministry for Education, Science, and Research (BMBWF), Ministry of Science and Technology (Israel), Formas (Sweden). DM gratefully acknowledges funding from the Ministry of Science and Innovation of Spain (ACPIN2017-117 and PID2019-108973RB-C22).Peer reviewe

GDF15 Provides an Endocrine Signal of Nutritional Stress in Mice and Humans.

GDF15 is an established biomarker of cellular stress. The fact that it signals via a specific hindbrain receptor, GFRAL, and that mice lacking GDF15 manifest diet-induced obesity suggest that GDF15 may play a physiological role in energy balance. We performed experiments in humans, mice, and cells to determine if and how nutritional perturbations modify GDF15 expression. Circulating GDF15 levels manifest very modest changes in response to moderate caloric surpluses or deficits in mice or humans, differentiating it from classical intestinally derived satiety hormones and leptin. However, GDF15 levels do increase following sustained high-fat feeding or dietary amino acid imbalance in mice. We demonstrate that GDF15 expression is regulated by the integrated stress response and is induced in selected tissues in mice in these settings. Finally, we show that pharmacological GDF15 administration to mice can trigger conditioned taste aversion, suggesting that GDF15 may induce an aversive response to nutritional stress.This work and authors were funded by the NIHR Cambridge Biomedical Research Centre; NIHR Rare Disease Translational Research Collaboration; Medical Research Council [MC_UU_12012/2 and MRC_MC_UU_12012/3]; MRC Metabolic Diseases Unit [MRC_MC_UU_12012/5 and MRC_MC_UU_12012.1]; Wellcome Trust Strategic Award [100574/Z/12/Z and 100140]; Wellcome Trust [107064 , 095515/Z/11/Z , 098497/Z/12/Z, 106262/Z/14/Z and 106263/Z/14/Z]; British Heart Foundation [RG/12/13/29853]; Addenbrooke’s Charitable Trust / Evelyn Trust Cambridge Clinical Research Fellowship [16-69] US Department of Agriculture: 2010-34323-21052; EFSD project grant and a Royal College of Surgeons Research Fellowship, Diabetes UK Harry Keen intermediate clinical fellowship (17/0005712). European Research Council, Bernard Wolfe Health Neuroscience Endowment, Experimental Medicine Training Initiative/AstraZeneca and Medimmune

Effetti della carenza o dell'eccesso di tessuto adiposo sul sistema immunitario: caratterizzazione delle cellule T regolatorie e del fenotipo dei macrofagi derivati dai monociti

La lipodistrofia comprende un gruppo di disordini rari ed eterogenei, con perdita parziale o generalizzata di tessuto adiposo bianco sottocutaneo. Si conoscono forme ad eziologia genetica e forme acquisite; la più comune tra le forme monogeniche è la lipodistrofia parziale familiare di Dunnigan. Indipendentemente dalla causa della patologia, il tessuto adiposo dei lipodistrofici è incapace di svolgere la sua funzione di deposito dei lipidi in eccesso; questo genera, in un apparente paradosso, un quadro clinico simile a quello degli obesi, caratterizzato da disturbi metabolici quali insulino-resistenza, dislipidemia, steatosi epatica non alcolica. È noto che anche nell’obesità patologica il tessuto adiposo sottocutaneo, deputato all’immagazzinamento dei trigliceridi, riduce questa sua funzione a causa di infiammazione, necrosi, ipossia. Studi condotti da diversi gruppi di ricerca pongono l’attenzione sulla relazione tra metabolismo e sistema immunitario, tanto da parlare di “immuno-metabolismo”, un tema emergente di ricerca. Scopo della mia tesi è di verificare se esistano delle variazioni nelle popolazioni di cellule T che modulano la reattività immunitaria e dei macrofagi derivati da monociti (MDMs), in pazienti lipodistrofici e obesi. Gli studi sono stati condotti su 16 donne lipodistrofiche, di cui 6 affette da sindrome di Dunnigan e 10 da forme eterogenee di lipodistrofia, 16 donne obese (BMI> 30 kg/m2) e 16 donne sane, normopeso, che rappresentano il gruppo dei controlli. In collaborazione con i medici del centro obesità dell’ospedale di Cisanello, sono stati determinati i parametri fisici, il profilo lipidico plasmatico, la glicemia, l’emoglobina glicata, i livelli di leptina. Per mezzo di citometria a flusso, è stato rilevato il numero circolante di cellule T regolatorie CD4/CD25hi (Tregs), che hanno la funzione di sopprimere l’iper-reattività del sistema immunitario e di cellule T invarianti natural killer (iNKTs), che promuovono un fenotipo anti-infiammatorio nei macrofagi. Sono stati caratterizzati i macrofagi derivati da monociti (MDMs), per morfologia e, tramite colorazione Oil-Red-O che ha definito 2 morfotipi principali, le lipid laden (LL) e le spindle-like (Sp) MDMs. Sono stati quindi eseguiti studi di espressione genica, utilizzando marcatori pro e anti-infiammatori. I risultati ottenuti mostrano che sia le pazienti lipodistrofiche che quelle obese hanno un profilo lipidico alterato, caratterizzato da livelli elevati di trigliceridi e di LDL ossidate e livelli inferiori di HDL rispetto ai controlli sani. Nelle pazienti lipodistrofiche le popolazioni di Tregs ed iNKTs sono significativamente diminuite, il numero delle LL-MDMs è maggiore mentre quello delle Sp-MDMs è minore. Il gruppo di pazienti lipodistrofici ad eziologia omogenea, rappresentato dai Dunnigan, ha mostrato risultati simili. La più alta prevalenza del fenotipo LL-MDMs trovato nelle pazienti lipodistrofiche è associato ad una minor espressione nei macrofagi del marcatore anti-infiammatorio IL-10 e con una maggior espressione di CD68, un fattore pro-infiammatorio. Nell’obesità le alterazioni del sistema immunitario risultano simili a quelle riscontrate nella lipodistrofia, seppur con un fenotipo meno pronunciato. Dall’analisi di correlazione emerge un’associazione significativa del morfotipo LL-MDMs con alti livelli di trigliceridi e di LDL ossidate e con bassi livelli di HDL. Si può concludere che lipodistrofia e obesità mostrano un numero ridotto di cellule T che sopprimono l’iper-reattività immunitaria e un aumento marcato di macrofagi che si infiltrano nel tessuto adiposo, dando accumulo di lipidi e di cellule infiammatorie. Il profilo lipidico è significativamente associato a questi cambiamenti. Questi risultati rafforzano il concetto che l’eccesso o la deplezione del tessuto adiposo possono comportare disfunzioni simili ed evidenziano ulteriormente la relazione tra il metabolismo e il sistema immunitario

Fluoxetine Modulates the Activity of Hypothalamic POMC Neurons via mTOR Signaling

Hypothalamic proopiomelanocortin (POMC) neurons are important players in the regulation of energy homeostasis; we previously demonstrated that environmental stimulation excites arcuate nucleus circuits to undergo plastic remodeling, leading to altered ratio between excitatory and inhibitory synaptic contacts on these neurons. The widely used selective serotonin reuptake inhibitor fluoxetine (FLX) is known to affect body weight. On the other hand, FLX administration mimics the effects of environmental stimulation on synaptic plasticity in the hippocampus and cortex. The mammalian target of rapamycin (mTOR) pathway is instrumental in these phenomena. Thus, we aimed at investigating whether and how FLX affects POMC neurons activity and hypothalamic mTOR function. Adult mice expressing green fluorescent protein (GFP) under the POMC promoter were treated with FLX for 3 weeks resulting in diminished body weight. Patch clamp recordings performed on POMC neurons indicate that FLX increases their firing rate and the excitatory AMPA-mediated transmission, and reduces the inhibitory GABAergic currents at presynaptic level. Immunofluorescence studies indicate that FLX increases the ratio between excitatory and inhibitory synaptic contacts on POMC neurons. These changes are associated with an increased activity of the hypothalamic mTOR pathway. Use of the mTOR inhibitor rapamycin blunts the effects of FLX on body weight and on functional and structural plasticity of POMC neurons. Our findings indicate that FLX is able to remodel POMC neurons, and that this may be partly mediated by the mTOR signaling pathway

Discovery of PTPRJ Agonist Peptides That Effectively Inhibit in Vitro Cancer Cell Proliferation and Tube Formation

PTPRJ is a receptor protein tyrosine phosphatase involved in both physiological and oncogenic pathways. We previously reported that its expression is strongly reduced in the majority of explored cancer cell lines and tumor samples; moreover, its restoration blocks in vitro cancer cell proliferation and in vivo tumor formation. By means of a phage display library screening, we recently identified two peptides able to bind and activate PTPRJ, resulting in cell growth inhibition and apoptosis of both cancer and endothelial cells. Here, on a previously discovered PTPRJ agonist peptide, PTPRJ-pep19, we synthesized and assayed a panel of nonapeptide analogues with the aim to identify specific amino acid residues responsible for peptide activity. These second-generation nonapeptides were tested on both cancer and primary endothelial cells (HeLa and HUVEC, respectively); interestingly, one of them (PTPRJ-19.4) was able to both dramatically reduce cell proliferation and effectively trigger apoptosis of both HeLa and HUVECs compared to its first-generation counterpart. Moreover, PTPRJ-pep19.4 significantly inhibited in vitro tube formation on Matrigel. Intriguingly, while ERK1/2 phosphorylation and cell proliferation were both inhibited by PTPRJ-pep19.4 in breast cancer cells (MCF-7 and SKBr3), no effects were observed on primary normal human mammary endothelial cells (HMEC). We further characterized these peptides by molecular modeling and NMR experiments reporting, for the most active peptide, the possibility of self-aggregation states and highlighting new hints of structure-activity relationship. Thus, our results indicate that this nonapeptide might represent a great potential lead for the development of novel targeted anticancer drug

Pyrvinium Pamoate Induces Death of Triple-Negative Breast Cancer Stem-Like Cells and Reduces Metastases through Effects on Lipid Anabolism

Cancer stem-like cells (CSC) induce aggressive tumor phenotypes such as metastasis formation, which is associated with poor prognosis in triple-negative breast cancer (TNBC). Repurposing of FDA-approved drugs that can eradicate the CSC subcompartment in primary tumors may prevent metastatic disease, thus representing an effective strategy to improve the prognosis of TNBC. Here, we investigated spheroid-forming cells in a metastatic TNBC model. This strategy enabled us to specifically study a population of long-lived tumor cells enriched in CSCs, which show stem-like characteristics and induce metastases. To repurpose FDA-approved drugs potentially toxic for CSCs, we focused on pyrvinium pamoate (PP), an anthelmintic drug with documented anticancer activity in preclinical models. PP induced cytotoxic effects in CSCs and prevented metastasis formation. Mechanistically, the cell killing effects of PP were a result of inhibition of lipid anabolism and, more specifically, the impairment of anabolic flux from glucose to cholesterol and fatty acids. CSCs were strongly dependent upon activation of lipid biosynthetic pathways; activation of these pathways exhibited an unfavorable prognostic value in a cohort of breast cancer patients, where it predicted high probability of metastatic dissemination and tumor relapse. Overall, this work describes a new approach to target aggressive CSCs that may substantially improve clinical outcomes for patients with TNBC, who currently lack effective targeted therapeutic options. SIGNIFICANCE: These findings provide preclinical evidence that a drug repurposing approach to prevent metastatic disease in TNBC exploits lipid anabolism as a metabolic vulnerability against CSCs in primary tumors.status: publishe

Discovery of PTPRJ Agonist Peptides That Effectively Inhibit <i>in Vitro</i> Cancer Cell Proliferation and Tube Formation

PTPRJ is a receptor protein tyrosine phosphatase involved in both physiological and oncogenic pathways. We previously reported that its expression is strongly reduced in the majority of explored cancer cell lines and tumor samples; moreover, its restoration blocks <i>in vitro</i> cancer cell proliferation and <i>in vivo</i> tumor formation. By means of a phage display library screening, we recently identified two peptides able to bind and activate PTPRJ, resulting in cell growth inhibition and apoptosis of both cancer and endothelial cells. Here, on a previously discovered PTPRJ agonist peptide, PTPRJ-pep19, we synthesized and assayed a panel of nonapeptide analogues with the aim to identify specific amino acid residues responsible for peptide activity. These second-generation nonapeptides were tested on both cancer and primary endothelial cells (HeLa and HUVEC, respectively); interestingly, one of them (PTPRJ-19.4) was able to both dramatically reduce cell proliferation and effectively trigger apoptosis of both HeLa and HUVECs compared to its first-generation counterpart. Moreover, PTPRJ-pep19.4 significantly inhibited <i>in vitro</i> tube formation on Matrigel. Intriguingly, while ERK1/2 phosphorylation and cell proliferation were both inhibited by PTPRJ-pep19.4 in breast cancer cells (MCF-7 and SKBr3), no effects were observed on primary normal human mammary endothelial cells (HMEC). We further characterized these peptides by molecular modeling and NMR experiments reporting, for the most active peptide, the possibility of self-aggregation states and highlighting new hints of structure–activity relationship. Thus, our results indicate that this nonapeptide might represent a great potential lead for the development of novel targeted anticancer drugs