Modulation of central and peripheral molecular clocks by proanthocyanidins

Els ritmes circadians permeten als organismes anticipar-se als canvis mediambientals i adaptar el metabolisme al patró d’alimentació i la disponibilitat d’aliments. De fet, les alteracions del ritme circadià provoquen trastorns del metabolisme com la síndrome metabòlica. Els ritmes circadians es mantenen pel rellotge central que es troba a l’ hipotàlem, tot i que els teixits perifèrics també presenten oscil•ladors circadians . Des d’un punt de vista molecular, el sistema circadià està constituït per gens rellotge que interacciones entre si, formant un cicle de regulació. La senyal més important per sincronizar aquest cicle amb l’exterior, és la llum. No obstant, hi ha altres senyals externes, com els cicle d’alimentació-dejuni i alguns components dels aliments, que també poden actuar sincronitzant el rellotge molecular. Les proantocianidines, que són una subclasse de flavonoides, indueixen una amplia gama d’efectes beneficiosos per la salut, millorant totes les patologies de la síndrome metabòlica. Per lo tant, l’objectiu principal d’aquesta tesi va ser avaluar la capacitat de les proantocianidines per modular el rellotge molecular a nivell central i perifèric, sota condicions estàndard o alterades. Els resultats demostren que les proantocianidines modulen els ritmes de expressió dels gens rellotge al llarg de les 24 hores, tant a nivell central con perifèric, tot i que els seus efectes depenen de si el tractament amb proantocianidines ha set durant la fase de llum o la fase de foscor. A més, els efectes sobre el sistema estan associats a canvis de la fluctuació ciracadiana d’alguns metabòlits importants en plasma, o dels nivells de NAD en el fetge. En conjunt, aquests resultats suggereixen que les proantocianidines podrien promoure els seus efectes beneficiosos sobre el metabolisme a través de la seva interacció amb el sistema circadià.Circadian rhythms allow organisms to anticipate environmental changes and to adapt the metabolism to feeding regime and food availability. In fact, alterations of circadian rhythm induce metabolic disturbances, such as metabolic syndrome. Circadian rhythms are maintained by a central clock in the hypothalamus, but circadian clocks are also present in peripheral tissues. At molecular level, the clock system is composed by feedback loops of core-clock and clock-controlled genes. The most important synchronizer of the clock system is light, but other external cues, such as fasting-feeding time or food components, also act as synchronizers. Proanthocyanidins, a flavonoid sub-class, are reported to have a vast range of beneficial effects improving all the components of the metabolic syndrome. Therefore, the main objective of this thesis was to evaluate the capacity of proanthocyanidins to modulate the central and peripheral molecular clocks under standard or disrupted conditions. Results show that proanthocyanidins modulate the 24-h rhythm expression of clock-core and clock-controlled gens in the central and peripheral clocks. However, the time of proanthocyanidin administration, in the light or dark phase, determine the precise effect on the molecular clock. The modulation of the clock system is associated with variations of the circadian fluctuation of some important metabolites in plasma or NAD levels in liver. Overall these results suggest that proanthocyanidins could mediate their beneficial metabolic effects through their interaction with the clock machinery.Los ritmos circadianos permiten a los organismos anticiparse a los cambios medioambientales y adaptar el metabolismo al patrón de alimentación y la disponibilidad de alimentos. De hecho, alteraciones del ritmo circadiano provocan trastornos del metabolismo como el síndrome metabólico. Los ritmos circadianos se mantienen por la acción del reloj central ubicado en el hipotálamo, aunque la mayoría de tejidos periféricos también disponen de reloj molecular. Desde un punto de vista molecular, el sistema circadiano está compuesto por genes “reloj” que interaccionan entre sí, formando un bucle de regulación. La señal externa más importante que sincroniza el sistema circadiano con el exterior es la luz, pero los ciclos de alimentación y ayunas, así como algunos componentes de los alimentos también actúan como señales externas sincronizadoras del reloj molecular. Las proantocianidinas, que son una subclase de los flavanoides, ejercen una amplia gama de efectos beneficiosos sobre la salud, mejorando todas las patologías del síndrome metabólico. Por lo tanto, el objetivo de la presente tesis fue evaluar la capacidad de las proantocianidinas para modular el reloj molecular a nivel central y periférico, bajo situaciones estándar o alteradas. Los resultados muestran que las proantocianidinas modulan el ritmo de expresión de los genes reloj a lo largo de las 24 horas, tanto a nivel central como periférico, aunque sus efectos dependen de si el tratamiento con proantocianidinas se ha realizado durante la fase de luz o la fase de oscuridad. Además, los efectos sobre el sistema circadiano están asociados a modificaciones en la fluctuación circadiana de algunos metabolitos importantes en plasma, o de los niveles de NAD en el hígado. En conjunto, estos resultados sugieren que las proantocianidinas podrían mediar sus efectos beneficiosos sobre el metabolismo a través de su interacción con el reloj molecular

Experimentació amb grans primats

Treball presentat a l'assignatura de Deontologia i Veterinària Legal (21223

Canine sterile steroid-responsive lymphadenitis in 49 dogs

OBJECTIVES:To report clinical and laboratory features, treatment responses and outcome in dogs diagnosed with sterile steroid-responsive lymphadenitis in the United Kingdom. MATERIALS AND METHODS:Medical records of dogs diagnosed with sterile steroid-responsive lymphadenitis from 2009 to 2016 at six specialist referral centres were evaluated retrospectively. RESULTS:The study included 49 dogs. Springer spaniels appeared to be over-represented (16 of 49 dogs). Young dogs (median age: 3 years and 9 months) and females (31 of 49) were frequently affected. Clinical presentation was variable, with pyrexia (39 of 49), lethargy (35 of 49) and anorexia (21 of 49) the most commonly reported clinical signs. Lymph node cytology or histopathology demonstrated neutrophilic, pyogranulomatous, granulomatous or necrotising lymphadenitis without a detectable underlying cause in all cases. Because a sterile immune-mediated aetiology was suspected, all dogs received prednisolone, which was followed by rapid resolution of clinical signs and lymphadenopathy in most cases. CLINICAL SIGNIFICANCE:Sterile steroid-responsive lymphadenitis should be considered in dogs with pyrexia of unknown origin with inflammatory lymphadenopathy if no underlying cause can be found and often responds well to immunosuppressive corticosteroid therapy

Myoglobin‐mediated lipid shuttling increases adrenergic activation of brown and white adipocyte metabolism and is as a marker of thermogenic adipocytes in humans

Background: Recruitment and activation of brown adipose tissue (BAT) results in increased energy expenditure (EE) via thermogenesis and represents an intriguing therapeutic approach to combat obesity and treat associated diseases. Thermogenesis requires an increased and efficient supply of energy substrates and oxygen to the BAT. The hemoprotein myoglobin (MB) is primarily expressed in heart and skeletal muscle fibres, where it facilitates oxygen storage and flux to the mitochondria during exercise. In the last years, further contributions of MB have been assigned to the scavenging of reactive oxygen species (ROS), the regulation of cellular nitric oxide (NO) levels and also lipid binding. There is a substantial expression of MB in BAT, which is induced during brown adipocyte differentiation and BAT activation. This suggests MB as a previously unrecognized player in BAT contributing to thermogenesis. Methods and results: This study analyzed the consequences of MB expression in BAT on mitochondrial function and thermogenesis in vitro and in vivo. Using MB overexpressing, knockdown or knockout adipocytes, we show that expression levels of MB control brown adipocyte mitochondrial respiratory capacity and acute response to adrenergic stimulation, signalling and lipolysis. Overexpression in white adipocytes also increases their metabolic activity. Mutation of lipid interacting residues in MB abolished these beneficial effects of MB. In vivo, whole-body MB knockout resulted in impaired thermoregulation and cold- as well as drug-induced BAT activation in mice. In humans, MB is differentially expressed in subcutaneous (SC) and visceral (VIS) adipose tissue (AT) depots, differentially regulated by the state of obesity and higher expressed in AT samples that exhibit higher thermogenic potential. Conclusions: These data demonstrate for the first time a functional relevance of MBs lipid binding properties and establish MB as an important regulatory element of thermogenic capacity in brown and likely beige adipocytes. Keywords: energy expenditure; hemoprotein; metabolism; obesity; oxphos; uncoupling protein

Nutrient supply affects the mRNA expression profile of the porcine skeletal muscle

Background: The genetic basis of muscle fat deposition in pigs is not well known. So far, we have only identified a limited number of genes involved in the absorption, transport, storage and catabolism of lipids. Such information is crucial to interpret, from a biological perspective, the results of genome-wide association analyses for intramuscular fat content and composition traits. Herewith, we have investigated how the ingestion of food changes gene expression in the gluteus medius muscle of Duroc pigs. Results: By comparing the muscle mRNA expression of fasted pigs (T0) with that of pigs sampled 5 h (T1) and 7 h (T2) after food intake, we have detected differential expression (DE) for 148 (T0-T1), 520 (T0-T2) and 135 (T1-T2) genes (q-value of 1.5). Many of these DE genes were transcription factors, suggesting that we have detected the coordinated response of the skeletal muscle to nutrient supply. We also found DE genes with a dual role in oxidative stress and angiogenesis (THBS1, THBS2 and TXNIP), two biological processes that are probably activated in the post-prandial state. Finally, we have identified several loci playing a key role in the modulation of circadian rhythms (ARNTL, PER1, PER2, BHLHE40, NR1D1, SIK1, CIART and CRY2), a result that indicates that the porcine muscle circadian clock is modulated by nutrition. Conclusion: We have shown that hundreds of genes change their expression in the porcine skeletal muscle in response to nutrient intake. Many of these loci do not have a known metabolic role, a result that suggests that our knowledge about the genetic basis of muscle energy homeostasis is still incomplete

Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences and Countermeasures.

Circadian (∼ 24 hour) timing systems pervade all kingdoms of life, and temporally optimize behaviour and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behaviour and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these too are increasingly subject to disruption. A large proportion of the world's population is at increased risk of environmentally-driven circadian rhythm and sleep disruption, and a minority of individuals are also genetically predisposed to circadian misalignment and sleep disorders. The consequences of disruption to the circadian system and sleep are profound and include myriad metabolic ramifications, some of which may be compounded by adverse effects on dietary choices. If not addressed, the deleterious effects of such disruption will continue to cause widespread health problems; therefore, implementation of the numerous behavioural and pharmaceutical interventions that can help restore circadian system alignment and enhance sleep will be important

Nutrients and the circadian clock: A partnership controlling adipose tissue function and health.

White adipose tissue (WAT) is a metabolic organ with flexibility to retract and expand based on energy storage and utilization needs, processes that are driven via the coordination of different cells within adipose tissue. WAT is comprised of mature adipocytes (MA) and cells of the stromal vascular cell fraction (SVF), which include adipose progenitor cells (APCs), adipose endothelial cells (AEC) and infiltrating immune cells. APCs have the ability to proliferate and undergo adipogenesis to form MA, the main constituents of WAT being predominantly composed of white, triglyceride-storing adipocytes with unilocular lipid droplets. While adiposity and adipose tissue health are controlled by diet and aging, the endogenous circadian (24-h) biological clock of the body is highly active in adipose tissue, from adipocyte progenitor cells to mature adipocytes, and may play a unique role in adipose tissue health and function. To some extent, 24-h rhythms in adipose tissue rely on rhythmic energy intake, but individual circadian clock proteins are also thought to be important for healthy fat. Here we discuss how and why the clock might be so important in this metabolic depot, and how temporal and qualitative aspects of energy intake play important roles in maintaining healthy fat throughout aging

Interdependence of nutrient metabolism and the circadian clock system: Importance for metabolic health

Background: While additional research is needed, a number of large epidemiological studies show an association between circadian disruption and metabolic disorders. Specifically, obesity, insulin resistance, cardiovascular disease, and other signs of metabolic syndrome all have been linked to circadian disruption in humans. Studies in other species support this association and generally reveal that feeding that is not in phase with the external light/dark cycle, as often occurs with night or rotating shift workers, is disadvantageous in terms of energy balance. As food is a strong driver of circadian rhythms in the periphery, understanding how nutrient metabolism drives clocks across the body is important for dissecting out why circadian misalignment may produce such metabolic effects. A number of circadian clock proteins as well as their accessory proteins (such as nuclear receptors) are highly sensitive to nutrient metabolism. Macronutrients and micronutrients can function as zeitgebers for the clock in a tissue-specific way and can thus impair synchrony between clocks across the body, or potentially restore synchrony in the case of circadian misalignment. Circadian nuclear receptors are particularly sensitive to nutrient metabolism and can alter tissue-specific rhythms in response to changes in the diet. Finally, SNPs in human clock genes appear to be correlated with diet-specific responses and along with chronotype eventually may provide valuable information from a clinical perspective on how to use diet and nutrition to treat metabolic disorders. Scope of review: This article presents a background of the circadian clock components and their interrelated metabolic and transcriptional feedback loops, followed by a review of some recent studies in humans and rodents that address the effects of nutrient metabolism on the circadian clock and vice versa. We focus on studies in which results suggest that nutrients provide an opportunity to restore or, alternatively, can destroy synchrony between peripheral clocks and the central pacemaker in the brain as well as between peripheral clocks themselves. In addition, we review several studies looking at clock gene SNPs in humans and the metabolic phenotypes or tendencies associated with particular clock gene mutations. Major conclusions: Targeted use of specific nutrients based on chronotype has the potential for immense clinical utility in the future. Macronutrients and micronutrients have the ability to function as zeitgebers for the clock by activating or modulating specific clock proteins or accessory proteins (such as nuclear receptors). Circadian clock control by nutrients can be tissue-specific. With a better understanding of the mechanisms that support nutrient-induced circadian control in specific tissues, human chronotype and SNP information might eventually be used to tailor nutritional regimens for metabolic disease treatment and thus be an important part of personalized medicine's future. Keywords: Circadian, Metabolism, Nutrients, Synchrony, Nuclear receptor

Adipose Stromal Cell Expansion and Exhaustion: Mechanisms and Consequences

Adipose tissue (AT) is comprised of a diverse number of cell types, including adipocytes, stromal cells, endothelial cells, and infiltrating leukocytes. Adipose stromal cells (ASCs) are a mixed population containing adipose progenitor cells (APCs) as well as fibro-inflammatory precursors and cells supporting the vasculature. There is growing evidence that the ability of ASCs to renew and undergo adipogenesis into new, healthy adipocytes is a hallmark of healthy fat, preventing disease-inducing adipocyte hypertrophy and the spillover of lipids into other organs, such as the liver and muscles. However, there is building evidence indicating that the ability for ASCs to self-renew is not infinite. With rates of ASC proliferation and adipogenesis tightly controlled by diet and the circadian clock, the capacity to maintain healthy AT via the generation of new, healthy adipocytes appears to be tightly regulated. Here, we review the contributions of ASCs to the maintenance of distinct adipocyte pools as well as pathogenic fibroblasts in cancer and fibrosis. We also discuss aging and diet-induced obesity as factors that might lead to ASC senescence, and the consequences for metabolic health

Lead intoxication mimicking idiopathic epilepsy in a young dog

An 11-month-old neutered female cocker spaniel was referred for two generalised tonic-clonic epileptic seizures with a one-week interval of mild depression. On admission, physical and neurological examinations were unremarkable. Neurolocalisation was forebrain. Haematology, biochemistry, serology for infectious diseases, urinalysis and urine culture were unremarkable. Cerebral MRI revealed T1-weighted hyperintensity in the lentiform nuclei. Cerebrospinal fluid analysis was unremarkable. Idiopathic epilepsy was mistakenly diagnosed and phenobarbital was started. A delayed blood film examination revealed metarubricytosis, polychromasia and basophilic stippling, raising the suspicion of lead intoxication. Abdominal radiography revealed a metallic lead foreign body (lead curtain weight), which removed endoscopically. Treatment with CaEDTA, thiamine and D-penicillamine was started. This report highlights the importance of including haematology, blood smear examination, biochemistry and urinalysis in the diagnostic workup of acute epileptic seizures particularly in young dogs. Lead intoxication should be included in the differential diagnosis in these patients, as modern lead sources still exist in our environment