Molecular and functional characterization of human bone marrow adipocytes

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The vascular endothelium of the adipose tissue gives rise to both white and brown fat cells

Adipose tissue expansion involves the enlargement of existing adipocytes, the differentiation of adipocyte progenitors, and the development of the supporting vascular network. Although some data suggest that the adipocyte progenitors reside in the vasculature of the adipose tissue, their identity is not completely clear [1,2]. Here we address the hypothesis that a population of adipocytes derives from an endothelial cell (EC) lineage. We performed a detailed morphological analysis in developing murine WAT and BAT in order to highlight the features of adipocyte precursors. In addition, we used the VE-Cadherin- Cre/R26R mouse model to address the relationship between vascular ECs and adipose cells development. This lineage tracing model allowed the identification of cells that express the EC gene VE-Cadherin at any point during differentiation. Finally, we analyzed capillary sprouts arising from human subcutaneous fat tissue to evaluate the hypothesis that ECs forming these structures possess the capacity to transform into adipocytes. Ultrastructural analysis of discrete areas of intense adipogenesis, that we designated vasculo-adipocytic islets, revealed the presence of rare endothelial-pericytic cells that could represent an intermediate developmental step between the EC and the preadipocyte stage. Lineage tracing experiments using the VE-cadherin promoter revealed the expression of reporter genes in ECs, preadipocytes and adipocytes in white and brown fat depots. Furthermore, capillary sprouts (which have predominantly EC characteristics) from human adipose tissue were found to express Zfp423, a recently identified marker of preadipocyte determination [3]. In response to PPARγ activation the ECs lost progressively their structural and molecular characteristics, and formed structurally and biochemically defined adipocytes. We report morphological and genetic evidence that adipocytes in white and brown fat depots originate from cells that display endothelial characteristics and this is in accordance with the results published by other researchers [4] and also with previous works performed in our lab [5]

Altered adipocyte differentiation and unbalanced autophagy in type 2 Familial Partial Lipodystrophy: an in vitro and in vivo study of adipose tissue browning

Type-2 Familial Partial Lipodystrophy is caused by LMNA mutations. Patients gradually lose subcutaneous fat from the limbs, while they accumulate adipose tissue in the face and neck. Several studies have demonstrated that autophagy is involved in the regulation of adipocyte differentiation and the maintenance of the balance between white and brown adipose tissue. We identified deregulation of autophagy in laminopathic preadipocytes before induction of differentiation. Moreover, in differentiating white adipocyte precursors, we observed impairment of large lipid droplet formation, altered regulation of adipose tissue genes, and expression of the brown adipose tissue marker UCP1. Conversely, in lipodystrophic brown adipocyte precursors induced to differentiate, we noticed activation of autophagy, formation of enlarged lipid droplets typical of white adipocytes, and dysregulation of brown adipose tissue genes. In agreement with these in vitro results indicating conversion of FPLD2 brown preadipocytes toward the white lineage, adipose tissue from FPLD2 patient neck, an area of brown adipogenesis, showed a white phenotype reminiscent of its brown origin. Moreover, in vivo morpho-functional evaluation of fat depots in the neck area of three FPLD2 patients by PET/CT analysis with cold stimulation showed the absence of brown adipose tissue activity. These findings highlight a new pathogenetic mechanism leading to improper fat distribution in lamin A-linked lipodystrophies and show that both impaired white adipocyte turnover and failure of adipose tissue browning contribute to disease.We thank FPLD2 patients for donating biological samples. We thank the Italian Network for Laminopathies and the European Consortium of Lipodystrophies (ECLip) for support and helpful discussion. We thank Aurelio Valmori for the technical support. The studies were supported by Rizzoli Orthopedic Institute “5 per mille” 2014 project to MC, AIProSaB project 2016 and Fondazione Del Monte di Bologna e Ravenna grant 2015–2016 “New pharmacological approaches in bone laminopathies based on the use of antibodies neutralizing TGF beta 2” to GL. GL is also supported by PRIN MIUR project 2015FBNB5Y.S

Polarized Ends of Human Macula Densa Cells: Ultrastructural Investigation and Morphofunctional Correlations

ABSTRACT The morphology of the kidney macula densa (MD) has extensively been investigated in animals, whereas human studies are scanty. We studied the fine structure of human MD cells focusing on their apical and basal ends and correlating structure and function. The MD region was examined by transmission electron microscopy in six renal biopsies from patients with kidney disease. Ultrastructural analysis of MD cells was performed on serial sections. MD cells show two polarized ends. The apical portion is characterized by a single, immotile cilium associated with microvilli; apically, cells are joined by adhering junctions. In the basal portion, the cytoplasm contains small, dense granules and numerous, irregular cytoplasmic projections extending to the adjacent extraglomerular esangium. The projections often contain small, dense granules. A reticulated basement membrane around MD cells separates them from the extraglomerular mesangium. Although the fact that tissue specimens came from patients with kidney disease mandates extreme caution, ultrastructural examination confirmed that MD cells have sensory features due to the presence of the primary cilium, that they are connected by apical adhering junctions forming a barrier that separates the tubular flow from the interstitium, and that they present numerous basal interdigitations surrounded by a reticulated basement membrane. Conceivably, the latter two features are related to the functional activity of the MD. The small, dense granules in the basal cytoplasm and in cytoplasmic projections are likely related to the paracrine function of MD cells

USE OF ISOLATED MATURE ADIPOCYTES IN REGENERATIVE MEDICINE FOR THE RECONSTRUCTION AND REPARATION OF TISSUES

The present invention provides for the use of mature adipocytes isolated from the adipose tissue as multipotent cells in the regenerative medicine. The mature adipocytes isolated from the adipose tissue have been characterized before and after implant in the tissue of a recipient animal, showing a considerable plasticity in transdifferentiating into cell lines of a different nature than the original one as a response to suitable environmental stimuli

Resting heart rate variability predicts inhibitory control above and beyond impulsivity

Heart rate variability (HRV) has been linked to effective functioning of prefrontal-subcortical inhibitory circuits. Despite the recognized role of the prefrontal cortex (PFC) in executive functions linked to inhibitory capacity, studies linking HRV to executive functions are inconsistent, likely due to potential confounders. The present study sought to examine this relation in a sample of 50 healthy participants (31 females; Mage = 24.2 years) who underwent assessment of resting HRV and two executive tasks assessing inhibitory control, namely the Rule Shift Cards and the Hayling Sentence Completion Test. Hierarchical multiple regressions showed that HRV predicted performance on both tasks (i.e., time taken to inhibit a strongly activated response) above and beyond the role of sex, body mass index, and impulsivity. Present results disconfirm that the HRV-executive function association is only due to confounders, and corroborate such relationship with the use of two ecological tasks assessing inhibitory control. Current findings support the Neurovisceral Integration Model and provide plausible explanation for previous inconsistent result

REATTIVITÀ VAGALE IN RISPOSTA A STIMOLI APPETITIVI E NEUTRI IN SOGGETTI CON DIAGNOSI DI OBESITA’

L’obesità è caratterizzata da anomala assunzione di cibo e da eccessivo accumulo di grasso. Il comportamento alimentare è dipendente dall’osservazione di stimoli come il cibo. Un indice particolarmente adatto per studiare la risposta a questi stimoli nei disturbi del comportamento alimentare è la variabilità del battito cardiaco, un parametro di funzionamento del sistema nervoso parasimpatico in grado di riflettere la capacità di regolare le emozioni e di inibire comportamenti disfunzionali. Questo studio si propone di esplorare la variabilità del battito cardiaco alla presentazione di immagini legate al cibo in un gruppo di pazienti obesi e in soggetti normopeso. Si ipotizza che, per i soli pazienti, gli stimoli legati al cibo diventino ansiogeni e scatenino una risposta fisiologica di crollo vagale. Si ipotizza inoltre che questo non si verifichi di fronte a stimoli non legati al cibo. 24 pazienti obesi ricoverati (19 femmine; età: 49.20 ± 13.64; indice di massa corporea: 41.63 ± 8.09) e 37 soggetti normopeso (24 femmine; età: 25.08 ± 6.76; indice di massa corporea: 22.14 ± 2.74) sono stati sottoposti a monitoraggio elettrocardiografico durante una condizione di riposo (baseline), un compito sperimentale e una fase di recupero. Un sottogruppo di pazienti (n = 11) ha ripetuto il paradigma sostituendo gli stimoli legati al cibo con stimoli neutri (oggetti). I risultati mostrano una riduzione significativa della variabilità interbattito dei pazienti, ma non dei controlli (p < .05), di fronte al cibo. Inoltre, i pazienti mostrano un’incapacità di ritornare ai valori di base al termine del compito (attivazione fisiologica sostenuta; p < .05). Come previsto, di fronte a stimoli neutri, i pazienti non mostrano alcuna risposta di attivazione fisiologica (n.s.). I risultati confermano la relazione tra aspetti fisiologici e psicologici nei disturbi alimentari e giustificano future indagini sulla reattività del sistema nervoso autonomo a stimoli salienti in persone obese

Obesity is associated with lack of inhibitory control and impaired heart rate variability reactivity and recovery in response to food stimuli

Recent theories compare obesity with addiction in terms of lack of inhibitory control in both clinical populations. The present study hypothesized impaired inhibition in obese patients reflected both in executive functions and reduced vagal tone (indexed by a decrease in heart rate variability; HRV) in response to food stimuli. Twenty-four inpatients with obesity (19 women) and 37 controls (24 women) underwent ECG monitoring during baseline, food stimuli viewing, and a recovery phase. Tests and questionnaires assessing inhibitory control and psychopathological dispositions were also administered. As hypothesized, patients were characterized by deficits in all the tests measuring inhibitory capacities. Results also show greater HRV reduction and impaired HRV recovery in response to food stimuli in obese patients compared to controls. The drive to eat experienced by obese patients in the absence of caloric need may rely on impairments in inhibitory and vagal functioning. Results are discussed in terms of implications for therap

A large proportion of mediastinal and perirenal visceral fat of Siberian adult people is formed by UCP1 immunoreactive multilocular and paucilocular adipocytes

Many deleterious consequences for health of excessive fat accumulation are due to visceral fat. Browning of visceral fat is mainly cold dependent and has been proposed as a possible tool for future therapies of obesity and related disorders. In this paper, we studied the composition of mediastinal and perirenal visceral fat, collected at necropsy, of human adults that lived in Siberia, one of the coldest regions of the earth. Data showed that a consistent part of the mediastinal and perirenal fat (up to about 40%) had the morphology typical of brown adipocytes and that a relevant percentage of them (up to about 30%) also expressed the functional marker uncoupling protein 1 (UCP1). Patients living mainly outdoor had higher percentage of brown-like adipocytes with more intensely UCP1 immunoreactive cells. The presence of numerous UCP1 immunoreactive paucilocular cells, a transitional stage of transdifferentiating adipocytes, supports the idea that visceral fat can be converted to brown adipose tissue in adult humans in physiological conditions. Tyrosine hydroxylase immunoreactive noradrenergic parenchymal nerve fibers were positively correlated to the number of multilocular adipocytes in mediastinal fat, and a similar trend was also observed in the perirenal fat