Le diabète de type 2 (T2D) est un trouble métabolique de l’homéostasie du glucose. Il est caractérisé par une hyperglycémie chronique qui résulte en partie d’une production excessive de glucose par le foie conséquence au développement d’une résistance à l’insuline. Le T2D est une pathologie multifactorielle à la fois génétique et environnementale. Récemment des études d’associations de gènes (GWAS) dans différentes cohortes ont mis en évidence une forte corrélation entre le locus CDKN2A et le risque de développement du T2D en se basant sur certains paramètres métaboliques tel que la glycémie à jeun. Le locus CDKN2A code pour des protéines régulatrices du cycle cellulaire dont la protéine p16INK4a. p16INK4a est largement décrite dans la littérature pour son rôle suppresseur de tumeurs et comme marqueur de sénescence, cependant son rôle dans le contrôle de l’homéostasie hépatique du glucose n’a jamais été rapporté. Afin de déterminer le rôle de p16INK4a dans le métabolisme hépatique du glucose, nous avons utilisé in vivo des souris sauvages (p16+/+) et déficientes pour p16INK4a (p16-/-) et in vitro des hépatocytes primaires ainsi que la lignée AML12. Nous avons montrés qu’après un jeune, les souris p16-/- présentent une hypoglycémie moins prononcée qui se traduit par une expression hépatique plus élevée de gènes de la néoglucogenèse tels que PEPCK, G6Pase et PGC1a. De plus, les hépatocytes primaires de souris p16-/- présentent une meilleur réponse au glucagon que ceux des p16+/+. Enfin, nous avons montrés que la diminution d’expression de p16INK4a par siRNA dans les AML12 suffit à induire l’expression des gènes de la néoglucogenèse et potentialise la réponse de ces cellules à différents stimuli gluconéogenique. L’effet observé dépend de l’activation de la voie PKA-CREB-PGC1A. L’ensemble de ces données montrent pour la première fois que p16INK4a pourrait jouer un rôle un cours du développement du T2D. / P16INK4a is a tumor suppressor protein well described as a cell cycle regulator. p16INK4a blocks cyclin D/ cyclin dependent kinase (CDK) 4 activity by binding to the catalytic subunit of CDK4, preventing retinoblastoma protein phosphorylation and subsequently the release of the E2F1 transcription factor. As a consequence; the transcription of genes required for progression to the S phase is restrained. Recently, genome-wide association studies (GWAS) associated the CDKN2A locus, encoding, amongst other genes, p16INK4A, with an increased risk of type 2 diabetes (T2D) development. However, the pathophysiological link between p16INK4a and hepatic glucose homeostasis remains unknown. In this context, we investigated the role of p16INK4a in hepatic glucose metabolism in vivo using p16+/+ and p16-/- mice and in vitro using primary hepatocytes and the AML12 hepatocyte cell line.p16-/- mice exhibited a higher response to fasting as shown by an increased hepatic gluconeogenic gene expression including phosphoenolpyruvate carboxykinase (PEPCK), fructose-1,6-biphosphatase (F1,6P) and glucose-6-phosphatase (G6Pase). p16-/- mice displayed an enhanced hepatic gluconeogenic activity in vivo upon administration of pyruvate, a gluconeogenic substrate. Consistent with this, in vitro data show that p16-/- primary hepatocytes display an enhanced gluconeogenic response to glucagon. In addition, knock down of p16INK4a by siRNA in AML12 cells increased gluconeogenic gene expression. These effects were associated with an increased activity of the PKA-CREB signaling pathway which leads to increased PPARg coactivator 1 (PGC1)α expression, a key transcriptional co-activator that regulates genes involved in energy metabolism. These findings describe a new function for p16INK4a as an actor in the hepatic adaptation to metabolic stress and suggest that p16INK4a could play a role during T2D development .

Alcoholic Fatty Liver Disease (AFLD) is caused by excessive alcohol consumption and is a leading cause of liver related mortalities, with currently no treatments available. The goal of this project was to establish the effect of alcohol consumption on adipose tissue-derived secreted factors, adiponectin and C1q TNF Related Proteins 1-3 (CTRP1-3). We propose that excessive alcohol consumption will reduce circulating levels of adiponectin and CTRPs 1-3. Mice were fed a Lieber-Decarli control or alcohol diet for 10-days with a gavage (NIAAA model) or 6-weeks with no gavage (chronic model). Serum and adipose tissue were collected and CTRPs 1-3 and adiponectin levels were examined by immunoblot analysis. Our results indicate that long-term alcohol consumption effects adipokine secretion in a sex specific manner. Further research will be needed to explore the physiological relevance of these findings, to determine if these changes are beneficial to combat the negative effects of excessive alcohol consumption.

Mammalian ABC (ATP-binding cassette) transporters are integral membrane proteins that translocate allocrites across biological membranes using ATP as a substrate. ABCB1 is a polyspecific efflux pump which can confer multidrug resistance in cancer. ABCB1 is also expressed in a variety of normal tissues where it functions to prevent the accumulation of toxic allocrites. Direct inhibition of ABCB1 can therefore have detrimental effects on patients. Identification of ABCB1-interacting partners that influence trafficking or function would therefore provide alternative targets for therapy which may be cell- or tissue-type specific. The “split-ubiquitin” yeast two-hybrid system, that can detect protein:protein interactions at the plasma membrane, was used to screen for ABCB1-interactors in a human liver library. All candidates isolated from the screen interacted with ABCB1 in a non-specific manner when subjected to strict testing. ABCB4, a close relative of ABCB1, is expressed primarily at the hepatocyte canalicular membrane where it flops phosphatidylcholine (PC) into the outer leaflet for extraction by bile salts. Many ABCB4 non-synonymous mutations have been linked to cholestatic liver diseases in humans, but data confirming an impact on ABCB4 function is lacking. Transient expression of wild-type (WT) ABCB4 in tissue culture has proved difficult because the protein is toxic to HEK293T cells. However, co-expression of the phosphatidylserine flippase ATP8B1 (FIC1) and its accessory protein CDC50A allowed the cells to tolerate ABCB4. To investigate the impact of SNPs on ABCB4 function, equivalent changes were introduced into the ABCB4 cDNA for transient expression in the presence or absence of ATP8B1/CDC50A. ABCB4 expression and targeting to the plasma membrane were monitored by western analysis and confocal microscopy, respectively, and, by “feeding” the transfected cells [methyl-3H]choline, PC efflux to added bile salt acceptor was measured. By thus mimicking the situation at the canalicular membrane I report the preliminary characterisation of nine variants of ABCB4 that have been linked to cholestatic liver disease.

OBJECTIVE. To identify clinical, socio-demographic, dietary and biological markers to be used in a non-invasive and cost-effective clinical tool for screening for non-alcoholic fatty liver disease (NAFLD) in obese adolescents. METHODS. We conducted a cross-sectional analysis using baseline data from 77 obese adolescents enrolled in a drug trial for the Glaser Pediatric Research Network, between October 2003 and August 2007. NAFLD was defined as the presence of fatty liver infiltration assessed by computed tomography. Receiver operation characteristic (ROC) analyses were performed to identify variables with the highest area under the curve (AUC) for NAFLD. Serum biomarkers were dichotomized using sensitivity analyses to identify the best cutoff point for NAFLD. Multiple logistic regression models were created to predict prevalent NAFLD. RESULTS. Serum triglycerides was identified as the best biomarker for NAFLD (AUC 0.790; pseudo R2 0.235). Additional adjustment for sex, age and Tanner stage improved the AUC to 0.846 and the pseudo R2 to 0.290. We then explored adding a simple biochemical marker for predicting NAFLD (HOMA-B, ALT or glutamate) and found that HOMA-B led to greater improvement in AUC, ALT to a greater improvement in sensitivity and glutamate to a greater improvement in the pseudo R2. Thus, all three factors individually improved overall model performance to some degree and inclusion of all three led to an AUC=0.907 and pseudo R2=0.433. Our second objective was to develop a more complex exploratory model starting with the inclusion of important clinical predictors (triglycerides, sex, age, Tanner stage, SBP, BMI, waist circumference); this yielded an AUC of 0.871 and pseudo R2 of 0.342. Further adjustment for HOMA-B, ALT and glutamate gave an AUC=0.913 and pseudo R2=0.497. CONCLUSION. Simple clinical and biochemical factors may be used to screen for prevalent NAFLD. Our simplest clinically relevant model using triglycerides, age, sex and Tanner stage provided a reasonable screening tool for NAFLD in obese adolescents. A second more complex model that warrants further testing includes triglycerides, sex, age, Tanner stage, SPB, BMI, waist circumference, HOMA-B, ALT and glutamate. In this study, this model was more accurate for detecting undiagnosed cases of NAFLD in this pediatric population.

The non-alcoholic fatty liver disease (NAFLD) is the most common liver pathology in developed countries with an estimated prevalence of 20 to 30% in the American population. A typically benign and asymptomatic pathology, NAFLD is characterized by hepatic steatosis and abnormal levels of hepatic enzymes stemming from an increase in circulating free fatty acids originating from white adipose tissue lipolysis, an increased de novo lipogenesis, reduced fatty acid oxidation and decreased hepatic triglycerides secretion, all within an insulin resistance context. NAFLD has the potential to progress to the non-alcoholic steatohepatitis (NASH), a condition marked by inflammation, advanced oxidative stress and fibrosis. NASH is expected to be the leading cause of liver transplant by 2020 due to its complications (i.e.: cirrhosis, hepatocellular carcinoma and liver failure). Various xenobiotics such as pesticides have been shown to promote the apparition and development of NAFLD. Of interest to this study is the neonicotinoid imidacloprid, more contemporarily known for its suspected role in the colony collapse disorder of various anthophilae species. Imidacloprid has been shown to induce hepatic oxidative stress in rats, a significant factor in the development of NAFLD and its progression to NASH. Lifestyle modifications, namely physical exercise, is a current treatment which has been proven beneficial to prevent and treat NAFLD by reducing hepatic steatosis, oxidative stress and improving insulin sensitivity. The role of any neonicotinoid on the development of NAFLD has yet to be examine and few have looked at the role of exercise in the treatment of NAFLD brought about by pesticide contamination.

Introdução: Doentes Hepáticos mesmo após o Transplante de Fígado (TF) apresentam heranças fisiopatológicas que podem influenciar na diminuição da Capacidade Funcional (CF). Objetivo: Traçar o perfil dos pacientes pós TF em relação à CF, e definir quais os melhores exercícios físicos para compor futuro programa de condicionamento físico dos pacientes, tanto antes como depois do TF. Métodos: Estudo transversal com 52 pacientes submetidos ao TF entre os anos de 2002 e 2013. Foi realizado o Teste de Caminhada de 6 minutos (TC6). Resultados: 51,9% dos pacientes eram homens, sendo a média de idade da amostra 58 + 10,26 anos. Entre os participantes, 48,1% eram hipertensos, 42,3% obesos e 40,4% tinham diabetes tipo II. Tacrolimus é o medicamento mais utilizado em 84,6% dos pacientes. O DPTC6 média total foi de 497 + 90 metros, onde os homens andavam distância média mais alta que as mulheres (531 + 70 e 460 + 95 metros respectivamente). Sexo e Idade foram significativas (p=0,002 e p=0,011), evidenciando que a média do TC6 é maior em homens mais jovens do que em mulheres, independentemente do tempo transcorrido após o TF (p>0,05). Em relação a prática de exercícios físicos, apesar de não ser estatisticamente significativa, evidenciou-se que praticantes possuem melhores DPTC6. Conclusão: A DPTC6 por pacientes já submetidos ao Transplante de Fígado no Hospital de Clínicas de Porto Alegre, é indicativa de boa capacidade funcional, principalmente entre os pacientes mais jovens, os do sexo masculino e praticantes de exercícios físicos. / Introduction: The pathophysiological profile of patients with liver disease may impact functional capacity even after liver transplantation (LT). Objective: To describe functional capacity after LT in a group of Brazilian patients. Methods: This cross-sectional study included 52 patients submitted to LT between 2002 and 2013. Functional capacity was determined using the six-minute walk test (6MWT). Results: The mean age of the overall sample was 58 ± 10.26 years, and 51.9% were male. Hypertension was detected in 48.1%, obesity in 42.3%, and type 2 diabetes in 40.4%. Tacrolimus was the most used medicine (84.6% of patients). The mean distance traveled in the 6MWT was 497 + 90 m (531 ± 70 m for males vs. 460 ± 95 m for females). Gender and age were significantly associated with 6MWT results (p=0.002 and p=0.011), showing a higher mean 6MWT distance in younger men than in women, regardless of the time elapsed since LT (p<0.05). In relation to physical exercise, physically active individuals had more favorable 6MWT results; however, this association was not statistically significant. Conclusion: The present group of LT patients had good functional capacity as measured by the 6MWT, especially younger patients, male patients, and physically active patients.

La consommation excessive d’alcool est la première cause de cirrhose en France. L’atteinte hépatique débute par une stéatose (accumulation de triglycérides dans les hépatocytes) qui peut évoluer vers un état inflammatoire (hépatite alcoolique) lors d’une consommation chronique d’alcool. La maladie peut ensuite évoluer vers la fibrose, la cirrhose et jusqu'à l’hépatocarcinome. La mortalité des formes aiguës de l’hépatite alcoolique sévère est comprise entre 50 et 75%. La corticothérapie est le seul traitement qui peut améliorer le pronostic à court terme. D’autres facteurs que la seule consommation excessive d’alcool interviennent dans la genèse des lésions hépatiques. Ainsi, parmi les sujets ayant une forte consommation d’alcool à long terme, la majorité des patients développent une stéatose mais seulement 10 à 35% développeront une hépatite et 8 à 20% évolueront vers la cirrhose. La recherche de facteurs qui relient la consommation d’alcool et la nature et progression des lésions hépatiques est donc essentielle pour trouver de nouvelles cibles thérapeutiques améliorant la prise en charge de ces formes graves. Afin de rechercher quels sont ces facteurs, nous avons utilisé un modèle murin d’alcoolisation. Nous avons utilisé un régime Lieber de Carli (LDC) enrichi en graisses, additionné d’alcool ou non. Nous avons orienté notre projet vers un axe microbiote-inflammation hépatique en analysant l’évolution des populations bactériennes intestinales au cours de la surconsommation d’alcool chez la souris. Des résultats nous ont montré que les Bacteroides variaient grandement d’une animalerie à l’autre. L’objet de nos travaux était d’étudier l’effet de la modulation des Bacteroides sur l’apparition des lésions hépatiques lors de la maladie alcoolique du foie. / Excessive alcohol consumption in the first cause of liver cirrhosis in France. Liver damages begin with steatosis (accumulation of fat in hepatocytes), which can progress to an inflammatory state (alcoholic hepatitis) during a long-term chronic alcohol consumption. Then, the disease can degenerate in liver fibrosis, cirrhosis and reach the hepatocarcinoma state. The mortality rate of acute alcoholic hepatitis ranges from 50% to 75%. Treatment based on corticoids is the only available and efficient treatment to improve the short-term prognosis. Other factors than only excessive alcohol consumption play a role in the onset of hepatic damages. Among patients having a long-term alcohol excessive consumption, most of them will develop a steatosis, whereas only 10% to 35% will develop alcoholic hepatitis and only 8 to 20% a liver cirrhosis. Researching these factors linking alcohol consumption and the nature and onset of liver injuries is of the utmost importance in order to find new therapeutic targets improving the patient life expectancy.In order to research these actors, we used a mice alcoholization model. We used a Lieber DeCarli diet, enriched in fat, added with ethanol or not. We studied the link between intestinal microbiota composition and the onset of liver injuries, by analyzing bacterial populations during an excessive alcohol consumption in mice. We discovered that one of the major bacterial population composing the intestinal microbiota, Bacteroides, underwent differential modifications from one animal housing facility to the other. The aim of our work was to modulate the Bacteroides population and study its effects on liver injuries.

研究背景及實驗目的: 非酒精性脂肪性肝炎(NASH)使得肥胖和2 型糖尿病變得複雜，肝臟炎症的持續產生是其主要的發病機理。CXCL10 是一種促進炎症的細胞因數，其在肥胖和2 型糖尿病中的表達顯著升高。CXCL10 以及其受體CXCR3 是否在NASH 的發生發展中起作用尚不清楚。在本研究中，我們探索了CXCL10 以及其受體CXCR3 在脂肪性肝炎中的功能， 並評估了CXCL10 在NASH 中的臨床價值。 / 實驗方法：CXCL10 基因敲除鼠，CXCR3 敲除鼠以及野生型C57BL/6 小鼠給予蛋氨酸膽鹼缺乏食(MCD)4 周或者8 周。CXCL10 的信號通路以及下游靶點通過細胞因數分析，cDNA array, 蛋白DNA 結合實驗，自噬溶酶體系統分析進行檢測。為了闡明CXCL10 抑制對NASH 的預防治療作用，我們給MCD 餵養的小鼠注射抗CXCL10 抗體。用不同濃度的CXCL10 抗體以及CXCR3 抑制劑NIBR2130 幹預MCD 培養的肝細胞株AML-12。臨床研究中，我們收集了147個非酒精性脂肪肝患者以及73 個健康對照的血清，用酶聯免疫吸附試驗檢測血清中CXCL10 的水準。 / 結果：野生型小鼠給予MCD 餵養後，CXCL10 以及CXCR3 的表達升高，並出現脂肪性肝炎的表現。然而，MCD 飼養的CXCL10 以及CXCR3 基因敲除鼠中，脂肪性肝炎明顯減輕。CXCL10 通過促炎細胞因數的產生以及NK-κB 信號通路促進MCD 飼養的小鼠NASH 的發生。CXCL10 通過促進脂質合成的基因SREBP-1c, ChREBP 和 SCD-1 引起脂肪變性，並通過CYP2E1 以及 C/EBPβ 的上調引起氧化應激。值得注意的是，自噬的損傷在CXCL10 以及CXCR3 導致的脂肪性肝炎的進展中起重要作用。 MCD 飼養的野生型小鼠中p62 以及LC3-II 表達明顯高於CXCL10 以及CXCR3 基因敲除鼠。通過抗CXCL10 抗體中和CXCL10 可以減輕MCD 食引起的小鼠脂肪性肝炎以及MCD 培養液引起的AML-12 細胞損傷。高選擇性的CXCR3 抑制劑NIBR2130 也可以抑制MCD 引起的肝細胞損傷。我們進一步研究了CXCL10 的臨床應用價值，發現NASH 患者血清以及肝臟中CXCL10 的水準明顯升高。更重要的是，血液中CXCL10 的水準與肝小葉炎症程度有關，是NASH 的獨立危險因素。 / 結論：我們的研究首次發現CXCL10 以及其受體CXCR3 通過促進炎症，脂質聚集，氧化應激以及自噬缺乏在NASH 的發病中起重要作用。抑制CXCL10 或者CXCR3 為NASH 患者的治療提供了新的方法。CXCL10 可作為NASH 患者非侵入性診斷的標誌物。 / Background and aims: Non-alcoholic steatoheaptitis (NASH) complicates obesity and type 2 diabetes, while recruitment and perpetuation of liver inflammation is central to its pathogenesis. Expression of C-X-C motif chemokine 10 (CXCL10), a proinflammatory cytokine, correlates positively with obesity and type 2 diabetes. Whether CXCL10 and its receptor CXCR3 play a role in NASH is unknown. In this study, we investigated the functional significance of CXCL10 and its receptor CXCR3 in steatoheaptitis. Moreover, the clinical impact of CXCL10 in NASH was examined. / Methods: Gene-deleted CXCL10 (CXCL10-/-), CXCL10 receptor CXCR3 (CXCR3-/-) and C57BL/6 wildtype (WT) mice were fed methionine and choline-deficient (MCD) diet for 4 or 8 weeks. Cytokine profiling assay, cDNA array, protein-DNA binding activity assay and autophagosome-lysosome system analysis of CXCL10 signaling and downstream targets were performed. In other experiments, we injected neutralizing anti-CXCL10 monoclonal antibodies (mAb) into MCD diet-fed WT mice, while AML-12 cells were cultured in MCD medium in the presence of anti-CXCL10 mAb or CXCR3 inhibitor (NIBR2130) for 24 hours. Human serum was obtained from 147 patients with biopsy-proven non-alcoholic fatty liver disease and 73 controls. Circulating CXCL10 levels were determined by enzyme-linked immunosorbent assay. / Results: MCD-fed WT mice developed steatohepatitis with higher hepatic CXCL10 and CXCR3 expression. CXCL10-/- and CXCR3-/- mice were refractory to MCDinduced steatohepatitis. In WT mice with steatohepatitis, but not in CXCL10-/- mice, CXCL10 was associated with the induction of pro-inflammatory chemokines and cytokines, as well as activation of nuclear factor-κB (NF-κB) signaling. CXCL10 expression was linked to steatosis through lipogenic factors, including liver X receptors and its downstream targets (SREBP-1c, ChREBP and SCD-1), and also to oxidative stress (up-regulation of CYP2E1 and C/EBPβ). In particular, autophagy deficiency was involved in CXCL10- and CXCR3-induced steatohepatitis as indicated by p62 and LC3-I/II protein accumulation in MCD-fed WT mice than in CXCL10-/- and CXCR3-/- mice. Moreover, the impaired autophagic function was related to the reduction of lysosomal function in CXCL10- or CXCR3-induced NASH. Blockade of CXCL10 by anti-CXCL10 mAb protected against MCD-induced steatohepatitis in vivo and against MCD-mediated injury to AML-12 cells in vitro. The highly selective CXCR3 antagonist NIBR2130 also inhibited MCD-induced injury in AML-12 hepatocytes. We further investigated the clinical impact of CXCL10 and found circulating and hepatic CXCL10 levels were significantly higher in human NASH. Importantly, circulating CXCL10 level was correlated with the degree of lobular inflammation and was an independent risk factor for NASH patients. / Conclusions: We demonstrate for the first time that CXCL10 and its receptor CXCR3 plays a pivotal role in the pathogenesis of NASH by promoting inflammation, fatty acid accumulation, oxidative stress and autophagy deficiency. Blockade of CXCL10 or CXCR3 is a potential novel approach for NASH intervention. CXCL10 is a noninvasive biomarker for NASH patients. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhang, Xiang. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 145-167). / Abstracts also in Chinese.

Obesity can lead to a range of health problems including type 2 diabetes (T2DM), cardiovascular disease and non-alcoholic fatty liver disease (NAFLD), and causes an estimated 2.8 million deaths annually (2016). It is a growing epidemic affecting over 600 million people worldwide (in 2014), with 26.8% of the adult population in England alone being obese, an increase of 10% in the last decade, and 62.9% overweight or obese. This trend is predicted to continue, and is attributed to an increasingly sedentary lifestyle, coupled with a high calorie “western diet”, which is estimated to cost >£25billion/year in the UK (2015), which is predicted to rise to £49.9 billion by 2050. It is clear that both sex and genetics affect the extent to which individuals exposed to a high fat diet develop adiposity and its associated morbidities, although the mechanisms underlying these differences are not well understood. Here we explore this aetiology, focusing on poly(A)-binding protein 4 (PABP4), an RNA-binding protein in which polymorphisms associated with altered cholesterol levels and cardiovascular disease risk were identified in human GWAS studies. To this end, I take advantage of an unpublished Pabp4 knock-out mouse, maintained on either normal (ND) or high fat diet (HFD), to explore the role of PABP4 in determining the response to high fat diet. PABP4 is a poorly characterised member of the PABP family, which are multifunctional central regulators of global and mRNA-specific translation, and stability. In cell lines, PABP4 is predominantly cytoplasmic, consistent with such functions. However, analogously to PABP1, the prototypical PABP family member, PABP4 is relocalised to stress granules or the nucleus in response to specific cellular stresses and/or viral infections, suggesting a role in altering gene expression programs in responses to changing cellular conditions. Whilst the expression pattern of PABP4 within tissues has not been previously characterised, western blotting of adult mouse tissues revealed that PABP4 is highly expressed in tissues relevant to obesity, T2DM and NAFLD, such as adipose, pancreas, liver and muscle, consistent with the idea that it may play a role in regulating gene expression programs in response to HFD. Immunohistochemistry of tissue sections provided additional insight, revealing a distinct cellular distribution of PABP4 in some tissues, when compared to the well characterised PABP1. Birth weight and post-birth growth can affect adult metabolism. In particular, low birth weight and catch-up growth, characterised by preferentially putting down adipose over lean mass, increases the risk of metabolic conditions in adulthood, such as obesity, T2DM and cardiovascular disease. Therefore, Pabp4-/- and wildtype mice were weighed at birth and daily until weaning. Interestingly this revealed that Pabp4-/- mice have a reduced weight at birth that is exacerbated to weaning (21days (P21)) (5.7% and 18.3% reductions respectively). This analysis also uncovered a reduced survival to weaning, with both male and female Pabp4-/- mice being present at sub-Mendelian ratios by P21 (p=0.0056). Whilst most death occurred neonatally, Pabp4-/- mice showed an increased rate of attrition until weaning, preceded in some cases by an arrest of weight gain. Weight gain was also tracked from 4 weeks to 12 weeks of age on normal diet showing that Pabp4-/- mice had reduced weight into adulthood (12% reduction at 12wks). Analysis of weight gain by sex uncovered a sexually dimorphic effect of Pabp4-deficiency, with female, but not male, Pabp4-/- mice remaining reduced in weight compared to wildtype after 8 weeks on ND (13.4% reduction in female weight). Body composition analysis showed that fat mass was equivalent to wildtype at 12 weeks of age in both sexes but that female Pabp4-/- mice had a 14.3% reduction in lean mass. Neither the catch-up growth in males nor the reduced lean mass in females was sufficient to result in a change in glucose homeostasis. As the risk of developing metabolic disorders in adult life is a consequence of both genetic and environmental factors, such as diet, Pabp4-/- were placed on a HFD at 4 weeks of age for 8 weeks. HFD models the ‘western’ diet, and has been shown to induce obesity, insulin resistance and glucose intolerance in wildtype mice. Whereas Pabp4-/- mice were only distinguishable from wild-type in terms of female lean mass on normal diet, pronounced sexually dimorphic differences were observed in HFD fed mice. Male Pabp4-/- mice appeared to be partially protected from the negative effects of an 8 week HFD regimen, with a 44% decrease in adipose mass gain compared to wildtype despite equal lean mass. Pabp4-/- male mice also had significantly reduced ectopic lipid stores, with an 81% decrease in hepatic triglyceride concentration compared to wildtype, meaning that NAFLD has not developed. Furthermore, Pabp4- /- male mice did not develop hyperinsulinemia on HFD and retained insulin sensitisation (assessed via glucose tolerance test (GTT) and insulin tolerance test (ITT)), although they displayed wildtype-like elevated plasma glucose concentrations (compared to ND). Western blotting had detected high PABP4 levels in the pancreas, indicating a possible pancreatic origin of these alterations. However, immunofluorescence revealed that PABP4 was confined to the exocrine portion of the pancreas, and was undetectable in the insulin producing pancreatic beta cells, suggesting this phenotype may not be beta cell in origin. This is consistent with the fact that the Pabp4-/- male mice retained an appropriate glucose-induced burst of insulin secretion, and therefore insulin production appears unimpaired. Thus, the primary defect may reside in the exocrine pancreas, which aids digestion, or in other key metabolism related tissues (e.g. muscle, liver, adipose and brain), or a combination thereof. In HFD fed wildtype mice, insulin resistance is caused by increased adiposity and ectopic lipid depots, which blunt insulin stimulated signalling cascades, meaning that the normal responses to insulin (e.g. cellular up take of glucose in muscle and arrested glucose production in liver, to decrease plasma glucose concentrations), are impaired. Therefore, the absence of insulin resistance in HFD fed Pabp4-/- male mice may be a consequence of the reduced increase in adipose mass and ectopic lipid deposits detected in these mice, and their consequent lack of inhibition on insulin signalling pathways. The reduced adiposity was not a result of reduced food intake or dietary fat absorption as male Pabp4-/- mice did not eat less nor exhibit apparent steatorrhea (fatty stools). These results highlight that the Pabp4-/- male mice appear to have an alteration in energy use/storage, and the investigation of this will form the basis of future work. When fed HFD, female Pabp4-/- mice revealed a divergent phenotype to that of wildtype female mice and Pabp4-/- male mice. HFD fed Pabp4-/- female mice showed no difference to HFD-fed wildtype mice in terms of weight, but still exhibited the reduction in lean mass seen on ND, but now with a 22.8% increase in volume of adipose tissue. Together, this means that HFD fed Pabp4-/- females have a higher body fat percentage (32.6% compared to 25.9 % for wildtype females). In contrast to the males, there was no difference in terms of hepatic triglycerides in HFD fed Pabp4-/- female mice and they showed greater hyperglycaemia than wildtype (GTT), although like males they retained insulin sensitisation (ITT). These potentially conflicting results in terms of insulin sensitivity and plasma glucose concentrations may result from the alterations in body composition, which can confound results when lean mass is altered and total body weight is used for calculating doses for GTT/ITT. Interestingly, adiponectin, an adipokine normally found in inverse proportion to adipose mass, was increased in plasma from HFD fed Pabp4-/- female mice (21% increase from HFD fed wildtype mice). Whilst surprising given the increase fat mass of Pabp4-/- females, the insulin sensitising properties of adiponectin may help to explain the retained insulin sensitivity detected in the female Pabp4-/- mice. / The finding that HFD revealed metabolic differences in the Pabp4-/- mice lead to the question of whether Pabp4-/- mice have issues adapting to other situations which require modulation of energy storage and glucose homeostasis. One such event is pregnancy, when maternal regulation of insulin resistance is tightly modulated throughout gestation. We therefore characterised the maternal Pabp4-/- environment in late pregnancy (E18.5), when insulin sensitivity decreases to 40-60% lower than pre-pregnancy which results reduced maternal glucose uptake, freeing the glucose up for the rapidly developing foetus. Pregnant Pabp4-/- mice had elevated plasma insulin concentration post fasting (63.7% increase), however glucose homeostasis was wildtype-like, both in terms of plasma glucose and insulin concentrations, throughout a GTT. However, plasma glucose and insulin concentrations in E18.5 Pabp4-/- foetuses were significantly decreased (9% and 44.3% respectively). Pabp4-/- foetuses also had reduced foetal and placental weight/length parameters. This establishes that the differences in weight observed at birth were present by late gestation and secondly, that the reductions in both foetal glucose and insulin concentrations which may contribute to or underlie the reduced growth. It also suggests that the differences seen in adulthood on HFD may be a consequence of metabolic differences present during pregnancy. Taken together, these data support the hypothesis that PABP4 plays a key role in the regulation of mRNAs which are important in growth, post-natal survival and metabolic adaption to high fat diet.

Submitted by Natalia Vieira (natalia.vieira@famerp.br) on 2016-05-20T17:39:42Z No. of bitstreams: 1 giovannazanellisilva_dissert.pdf: 2457622 bytes, checksum: 3faf263a6839bd66d93d3bcefc887385 (MD5) / Made available in DSpace on 2016-05-20T17:39:42Z (GMT). No. of bitstreams: 1 giovannazanellisilva_dissert.pdf: 2457622 bytes, checksum: 3faf263a6839bd66d93d3bcefc887385 (MD5) Previous issue date: 2015-11-27 / Introduction: Nonalcoholic Fatty Liver Disease (NAFLD) is characterized by an increase in intracellular content of triglycerides; its prevalence worldwidely is nearly 20-30% of the population. This disease has spectral nature that includes steatosis and nonalcoholic steatohepatitis (NASH) in the absence of significant alcohol consumption. Although NAFLD may remain as a stable disease for longer periods, this condition may progress to advanced stages of cirrhosis and liver cancer. Diabetes Mellitus Type 2, insulin resistance and obesity are important risk factors, among others, for development of NAFLD, and are directly related to sedentary lifestyle and inappropriate eating habits. Thus, alteration in lifestyle, changes in eating habits and regular physical activity play a fundamental role in treating this disease. Aim: To evaluate the effectiveness of hypocaloric diet for the treatment of NASH as well as adherence to treatment. Methods: This is a prospective longitudinal open cohort study, in which 26 NASH patients were divided into 2 group: 15 patients in the control group and 11 patients in the treatment group which were followed up for 6 months. Both groups were diagnosed by liver biopsy. The treatment group was a given lifestyle change program with supervised low-calorie diet (20-25 kcal / kg actual weight / day), monitored exercise, standard treatment of metabolic syndrome and drug maintenance treatment with metformin and N- acetylcysteine. The control group received general guidelines on diet and weight loss, encouragement to practice physical exercise, standard treatment of metabolic syndrome and maintenance of drug treatment with metformin. Criteria for inclusion: patients with at least one of the component of metabolic syndrome; BMI ≥ 25 and ≤ 40 kg /m² and sedentary for at least three months. Criteria for exclusion: other concomitant liver diseases, alcohol intake greater than or equal to 21 drinks / week, or 140 g / day for men and 14 drinks / week or 70g / day for women, medication known to be associated with NAFLD, untreated hypothyroidism or hyperthyroidism, previous bariatric surgery, or uncontrolled psychiatric disorder. Diagnostic criteria: the diagnosis of NASH was done by liver biopsy in patients with steatosis on ultrasound or MRI and at least one risk factor for advanced fibrosis into the period up to one year before entering the study. The lifestyle change program in the treatment group had a weight loss goal of 5% or more of their initial weight within six months. Evaluation criteria: a monthly basis applied the clinical evaluation protocol and on a quarterly basis the laboratorial, according to the following variables: weight, height, body mass index, waist circumference, hip circumference, aminotransferase levels, gamma GT, total cholesterol and fractions, triglycerides. Statistical analysis: the descriptive variables were expressed as frequency, mean or median, standard deviation and variation as applicable. The Student t test and Mann-Whitney test were used for comparative analysis. It was admitted confidence interval of 95% and a significance level of P <0.05. Results: Of the 15 patients enrolled with a diagnosis of NASH who were submitted to nutritional treatment, 12 patients completed the six month follow-up of the study. The average age was 51.42 years ± 8.50, being 08 (66%) women and 04 (33%) men. Of this total, only one patient refused to carry out physical activity. Two (17%) among the 12 participants who completed the six month follow-up reached the percentage of expected weight loss. The average percentage of adaptation to the proposed diet was 82.93% ± 13.51%. Conclusion: The lifestyle change program tested for six months associated with NASH treatment, was not effective for clinical and biochemical improvement even with satisfactory adherence by most patients. Our data point out to the potential role of more restrictive diets and intensive supervision in this context combined with multidisciplinary team for the treatment of NASH. This real-life study produced crucial information for readjustment of the multidisciplinary treatment protocol for patients followed up in the service. / Introducao: A doenca hepatica gordurosa nao alcoolica (DHGNA) e caracterizada pelo aumento do conteudo intracelular de triglicerideos, com prevalencia mundial de aproximadamente 20 a 30% da populacao. Esta doenca tem natureza espectral que engloba esteatose e esteatohepatite nao-alcoolica (NASH), na ausencia de consumo significante de alcool. Embora DHGNA possa permanecer como uma doenca estavel por longos periodos, esta condicao pode progredir para estagios avancados de cirrose e cancer de figado. O Diabetes Mellitus Tipo 2, resistencia a insulina e obesidade sao importantes fatores de risco, dentre outros, para desenvolvimento da DHGNA, e estao diretamente relacionadas ao estilo de vida sedentario e habitos alimentares inapropriados. Dessa forma, alteracao no estilo de vida, mudancas nos habitos alimentares e atividade fisica regular tem papel fundamental no tratamento desta doenca. Objetivo: Avaliar a eficacia da dieta hipocalorica durante o tratamento do NASH, assim como, a adesao ao tratamento instituido. Metodo e Casuistica: Trata-se de um estudo de coorte aberto prospectivo, longitudinal, no qual foram incluidos consecutivamente 26 pacientes, divididos em dois grupos: 15 pacientes no grupo tratamento e 11 pacientes no grupo controle acompanhados durante 6 meses. Ambos tinham diagnostico de NASH por biopsia. O grupo tratamento recebeu programa de mudanca no estilo de vida com dieta hipocalorica supervisionada (20 - 25 kcal/kg de peso atual/dia), exercicio fisico supervisionado, tratamento padrao dos componentes da sindrome metabolica e manutencao de tratamento medicamentoso com metformina e N-acetilcisteina. O grupo controle recebeu orientacoes gerais de dieta e perda de peso, estimulo a pratica de exercicio fisico, tratamento padrao dos componentes da sindrome metabolica e manutencao do tratamento medicamentoso com metformina. Criterios de inclusao: portadores de pelo menos uma caracteristica de sindrome metabolica, IMC . 25 e . 40kg/m2, e sedentarios por no minimo tres meses. Criterios de exclusao: outras doencas hepaticas concomitantes, ingestao alcoolica igual ou superior a 21 doses/semana ou 140g/dia para homens e 14 doses/semana ou 70g/dia para mulheres, medicacao conhecidamente relacionada com DHGNA, hipotireoidismo ou hipertireoidismo nao tratados, pos operatorio de cirurgia bariatrica, compulsao alimentar ou outro disturbio psiquiatrico nao controlado. Criterios diagnosticos: o diagnostico de NASH foi feito por biopsia de figado em pacientes portadores de esteatose ao ultrassom ou ressonancia magnetica e pelo menos um fator de risco para fibrose avancada, no periodo de ate 1 ano antes da entrada no estudo. Programa de mudanca no estilo de vida no grupo tratado teve como meta a reducao minima ou superior a 5% de seu peso inicial no periodo de seis meses. Criterios de avaliacao: aplicado mensalmente o protocolo de avaliacao clinica e trimestralmente o laboratorial, de acordo com as seguintes variaveis: peso, altura, indice de massa corporal, circunferencia abdominal, circunferencia do quadril, niveis de aminotransferases, gama GT, colesterol total e fracoes, triglicerideos. Analise estatistica: as variaveis descritivas foram expressas em frequencia, media ou mediana, desvio padrao e variacao conforme aplicaveis. Foram utilizados os testes t de Student e teste de Mann-Whitney para analises comparativas. Foi admitido intervalo de confianca de 95% e nivel de significancia para P<0,05. Resultados: Dos 15 pacientes incluidos com diagnostico de NASH que foram submetidos ao programa de mudanca no estilo de vida, 12 pacientes concluiram o acompanhamento de 6 meses do estudo. A idade média foi de 51,42 anos ± 8,50, sendo 08 (66%) pessoas do gênero feminino e 04(33%) do gênero masculino. Deste total, apenas um paciente negou a realização de atividade física. Dois (17%) participantes dentre os 12 que concluíram os seis meses de acompanhamento atingiram a porcentagem de perda de peso esperada. A média da porcentagem de adequação à dieta proposta dos participantes do estudo encontrada foi de 82,93% ± 13,51%. Conclusão: O programa de mudança no estilo de vida testado durante seis meses associado ao tratamento do NASH, não foi eficaz para a melhora clínica e bioquímica mesmo com adesão satisfatória pela maioria dos pacientes. Este estudo de vida real produziu informações de fundamental importância para readequação do protocolo de atendimento multidisciplinar dos pacientes em acompanhamento no serviço.