The overall objective of this research was to investigate the status of tumor necrosis factor-?? (TNF-??), and molecules associated with its signaling, in the pathological state of hepatic steatosis. The effect of NSAID piroxicam, a cancer preventive agent also known to affect TNF-?? signaling on hepatic steatosis, was also investigated. The biological state of the tissue was assessed by examining the expression of TNF-?? signaling molecule in whole tissue, as well as in hepatic lipid raft. Lipid rafts are dynamic assemblies of cholesterol and sphingolipids, microdomains that form in the exoplasmic leaflet of the biological membranes shown to play a role in compartmentalization, modulation and integration of the cell signaling. In the present research, Zucker obese rats were used as a model of human obesity and insulin resistant state. These rats exhibit hepatic steatosis in adulthood similar to those noted in obese individuals. Female Zucker obese and lean rats (5 weeks old) were fed a semisynthetic diet with or without piroxicam (150 ppm). Zucker lean counterparts served as control. After 8 weeks of feeding, rats were euthanized and liver from each animal was collected. Liver tissue from each animal was processed for histology and biochemical analysis which included lipids and proteins (COX-1 and 2, TNF-??, TNF-RI and RII, IKK-??, I??B-?? and NF-??B). Liver histology and the level of total lipids confirmed that Zucker obese rats had hepatic steatosis, which was further augmented by piroxicam treatment. Whole tissue protein expression, using western blot, showed that the steatotic liver differed from non-steatotic livers by having lower levels of TNF-RII. TNF-RII showed a trend which was inversely proportional to the pathological state of the tissue. The obese-piroxicam liver had the lowest level of TNF-RII and lean livers had the highest (p<0.05). The total NF-??B level was higher in the obese and obese-piroxicam groups compared to the lean or lean-piroxicam groups (p<0.05). Piroxicam treatment lowered the level of NF-??B in obese and lean livers. I??B-?? was higher in obese livers than in lean livers. The nuclear level of NF-??B by western blot analysis showed the same pattern as noted in the whole tissue homogenate. However, the difference in the level between obese and lean was marked. The obese nuclei contained two to three fold higher levels of NF-??B protein than the lean liver nuclei. I??B-?? level was significantly higher in the obese liver tissues and nuclei than their lean counterparts. While transcriptionally active NF-??B was higher (p<0.05) in the obese livers than in the lean livers, the difference between obese and lean groups was not as significant as that noted for the level of NF-??B assessed by western blot. This suggests that the proportion of active NF-??B present in the nuclear fraction is much higher in the lean than in the obese nuclei. Lipid raft was extracted and identified successfully from obese and lean livers. The total caveolin and flotillin levels were significantly higher in the liver lipid rafts of the obese-piroxicam than that of the other groups. This is the group that also exhibited higher steatosis. Piroxicam treatment significantly decreased the level of caveolin in the lean liver and significantly increased the level of flotillin in the obese liver. While COX-1 was not detectable, however, the level of COX-2 and TNF-RII in lipid raft was opposite to the level noted in the whole tissue homogenate. TNFRII was highest in the obese-piroxicam lipid raft and lowest in the lean-piroxicam lipid raft. TNF-RII, COX-2, I??B-?? and NF-??B proteins were the molecules profoundly affected by the pathological state of the tissue and piroxicam treatment. This research is the first to report the presence of I??B-?? in the nuclear compartment with a higher level in the nuclei and whole tissue in the obese liver than in the lean liver. This research demonstrates that TNF-?? to NF-??B axis is altered in steatotic liver, and analysis of lipid rafts in steatotic and non-steatotic liver demonstrates that lipid rafts play a distinct role in modifying the biological availability of key proteins in the pathological state of liver steatosis.

Non-alcoholic fatty liver disease (NAFLD) is a common consequence of metabolic syndrome (MetS) with the least severe form of NAFLD being hepatic steatosis, which is the accumulation of intrahepatic fat. Omega-3 polyunsaturated fatty acids (n3 PUFAs) are fatty acids in our diets commonly found in marine animals (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and certain plants (α-linoleic acid [ALA]). Although past studies have examined the consumption of marine sources or plant sources on hepatic steatosis and MetS parameters, individual n3 PUFA have yet to be compared to each other. Thus fa/fa Zucker rats were provided n3 PUFA diets containing ALA, EPA or DHA for 8 weeks relative to a linoleic acid (LA)-rich n6 PUFA diet provided to fa/fa and lean Zucker rats. Comparisons were to baseline fa/fa Zucker rats. It was shown that DHA prevented the progression of hepatic steatosis and was associated with improvements in insulin resistance.

TGFβ ligands, activin and myostatin have been shown to stimulate insulin production and secretion. Antagonists, Follistatin (FST) and Follistatin like 3 (FSTL3) were partially and fully ablated, respectively, creating hyperinsulinemic mice with fatty liver. Much research has surfaced on the connection between hepatic steatosis and hepatic insulin resistance. We present two different models, each with a different mechanism behind the development of fatty liver. FST288-only mice have increased synthesis of mRNA and proteins responsible for hepatic triglyceride (TG) uptake, while our double mutants have increased synthesis of mRNA and proteins responsible for TG synthesis. This alteration was likely independent of hepatic insulin resistance as livers from both mouse lines were insulin sensitive. Experiments conducted in this study to realize the causal factor of hepatic steatosis can be performed on adipose and muscle tissues in the future to better characterize the phenotype.

Apoptosis is a genetically regulated form of cell death that occurs when the cell is exposed to physiological, pathogenic, or cytotoxic stimuli. Unregulated apoptosis (too much or too little apoptosis) at any time from embryogenesis to adulthood, can result in a variety of disease states, such as neurodegenerative disorders, autoimmunity, cardiovascular disease, liver and kidney problems, and cancer. A reasonable estimation is that either too little or too much cell death contributes to half of the main medical illnesses for which adequate therapy or prevention is lacking. The apoptotic pathways can be initiated by reactive oxygen species (ROS) and inflammatory molecules, both of which are believed to be up-regulated in a state of obesity. In addition, multiple studies have shown that the risk of developing cardiovascular disease, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and certain types of cancers increase with increasing degree of obesity in both men and women. Despite the well characterized association of obesity and disease incidence, the mechanisms by which obesity contributes to disease pathology are poorly understood. Previously, in our research group, it was shown that obese Zucker rats, which are the animal model of human obesity, are more prone to colon cancer and hepatic steatosis compare to their relative lean counterparts. Therefore, applying Real-Time RT-PCR, the expression levels of some pro- and anti-apoptotic members of the BCL-2 family of genes were investigated to figure out the possible effect of obesity on apoptotic gene expression levels. Also, apoptotic gene expression patterns of obese and lean Zucker rats after DNA damage induction were compared to each other in order to find the possible connection of apoptotic gene expression with disease progression in obese individuals. This is the first study comparing the expression level of BCL-2 family of genes in obese versus lean liver and colon tissue. In this study, it was shown that an obese genotype affects pro- and anti-apoptotic gene expression levels and patterns whether or not DNA damage has been induced in both liver and colon. The results show a clear alteration in apoptotic gene expression levels in obese individuals compared to their lean counterparts leading to the proposal that apoptosis may be involved in the obesity related colon cancer and liver steatosis.

The overall objective of this research was to investigate the status of tumor necrosis factor-α (TNF-α), and molecules associated with its signaling, in the pathological state of hepatic steatosis. The effect of NSAID piroxicam, a cancer preventive agent also known to affect TNF-α signaling on hepatic steatosis, was also investigated. The biological state of the tissue was assessed by examining the expression of TNF-α signaling molecule in whole tissue, as well as in hepatic lipid raft. Lipid rafts are dynamic assemblies of cholesterol and sphingolipids, microdomains that form in the exoplasmic leaflet of the biological membranes shown to play a role in compartmentalization, modulation and integration of the cell signaling. In the present research, Zucker obese rats were used as a model of human obesity and insulin resistant state. These rats exhibit hepatic steatosis in adulthood similar to those noted in obese individuals. Female Zucker obese and lean rats (5 weeks old) were fed a semisynthetic diet with or without piroxicam (150 ppm). Zucker lean counterparts served as control. After 8 weeks of feeding, rats were euthanized and liver from each animal was collected. Liver tissue from each animal was processed for histology and biochemical analysis which included lipids and proteins (COX-1 and 2, TNF-α, TNF-RI and RII, IKK-β, IκB-α and NF-κB). Liver histology and the level of total lipids confirmed that Zucker obese rats had hepatic steatosis, which was further augmented by piroxicam treatment. Whole tissue protein expression, using western blot, showed that the steatotic liver differed from non-steatotic livers by having lower levels of TNF-RII. TNF-RII showed a trend which was inversely proportional to the pathological state of the tissue. The obese-piroxicam liver had the lowest level of TNF-RII and lean livers had the highest (p<0.05). The total NF-κB level was higher in the obese and obese-piroxicam groups compared to the lean or lean-piroxicam groups (p<0.05). Piroxicam treatment lowered the level of NF-κB in obese and lean livers. IκB-α was higher in obese livers than in lean livers. The nuclear level of NF-κB by western blot analysis showed the same pattern as noted in the whole tissue homogenate. However, the difference in the level between obese and lean was marked. The obese nuclei contained two to three fold higher levels of NF-κB protein than the lean liver nuclei. IκB-α level was significantly higher in the obese liver tissues and nuclei than their lean counterparts. While transcriptionally active NF-κB was higher (p<0.05) in the obese livers than in the lean livers, the difference between obese and lean groups was not as significant as that noted for the level of NF-κB assessed by western blot. This suggests that the proportion of active NF-κB present in the nuclear fraction is much higher in the lean than in the obese nuclei. Lipid raft was extracted and identified successfully from obese and lean livers. The total caveolin and flotillin levels were significantly higher in the liver lipid rafts of the obese-piroxicam than that of the other groups. This is the group that also exhibited higher steatosis. Piroxicam treatment significantly decreased the level of caveolin in the lean liver and significantly increased the level of flotillin in the obese liver. While COX-1 was not detectable, however, the level of COX-2 and TNF-RII in lipid raft was opposite to the level noted in the whole tissue homogenate. TNFRII was highest in the obese-piroxicam lipid raft and lowest in the lean-piroxicam lipid raft. TNF-RII, COX-2, IκB-α and NF-κB proteins were the molecules profoundly affected by the pathological state of the tissue and piroxicam treatment. This research is the first to report the presence of IκB-α in the nuclear compartment with a higher level in the nuclei and whole tissue in the obese liver than in the lean liver. This research demonstrates that TNF-α to NF-κB axis is altered in steatotic liver, and analysis of lipid rafts in steatotic and non-steatotic liver demonstrates that lipid rafts play a distinct role in modifying the biological availability of key proteins in the pathological state of liver steatosis.

Apoptosis is a genetically regulated form of cell death that occurs when the cell is exposed to physiological, pathogenic, or cytotoxic stimuli. Unregulated apoptosis (too much or too little apoptosis) at any time from embryogenesis to adulthood, can result in a variety of disease states, such as neurodegenerative disorders, autoimmunity, cardiovascular disease, liver and kidney problems, and cancer. A reasonable estimation is that either too little or too much cell death contributes to half of the main medical illnesses for which adequate therapy or prevention is lacking. The apoptotic pathways can be initiated by reactive oxygen species (ROS) and inflammatory molecules, both of which are believed to be up-regulated in a state of obesity. In addition, multiple studies have shown that the risk of developing cardiovascular disease, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and certain types of cancers increase with increasing degree of obesity in both men and women. Despite the well characterized association of obesity and disease incidence, the mechanisms by which obesity contributes to disease pathology are poorly understood. Previously, in our research group, it was shown that obese Zucker rats, which are the animal model of human obesity, are more prone to colon cancer and hepatic steatosis compare to their relative lean counterparts. Therefore, applying Real-Time RT-PCR, the expression levels of some pro- and anti-apoptotic members of the BCL-2 family of genes were investigated to figure out the possible effect of obesity on apoptotic gene expression levels. Also, apoptotic gene expression patterns of obese and lean Zucker rats after DNA damage induction were compared to each other in order to find the possible connection of apoptotic gene expression with disease progression in obese individuals. This is the first study comparing the expression level of BCL-2 family of genes in obese versus lean liver and colon tissue. In this study, it was shown that an obese genotype affects pro- and anti-apoptotic gene expression levels and patterns whether or not DNA damage has been induced in both liver and colon. The results show a clear alteration in apoptotic gene expression levels in obese individuals compared to their lean counterparts leading to the proposal that apoptosis may be involved in the obesity related colon cancer and liver steatosis.

Many individuals presumed to have non-alcoholic fatty liver disease (NAFLD) consume moderate amounts of alcohol; however, little is known regarding patterns of alcohol use and how drinking behaviors may influence liver fat. We conducted a cross-sectional study of 2,475 participants of the Framingham Heart Study who underwent computed tomography (CT) to define liver fat. We performed multivariable-adjusted logistic regression models for the association between different alcohol drinking patterns, including the average alcoholic drinks/week, frequency of alcohol use, usual quantity of alcohol consumed, maximum drinks consumed in 24 hours, and binge drinking behavior, and CT-defined hepatic steatosis. We excluded heavy alcohol users defined as women who drink > 14 drinks/week and men who drink > 21 drinks/week. We also performed an analysis specific to beverage type (beer, wine, or liquor/spirit drinks).The prevalence of hepatic steatosis in our study sample (mean age ± standard deviation (SD) 49.8±10.2, 50.3% women) was 17.5%. Among individuals with presumed NAFLD, binge drinking occurred in 25.4% of individuals. In adjusted models, the odds of hepatic steatosis increased by 20% for each SD increase in the number of alcoholic drinks consumed per week (OR 1.20; 95% confidence interval (CI) 1.08, 1.36). Frequency of alcohol use (drinking days/week) was also associated with hepatic steatosis (OR 1.09; 95% CI 1.03, 1.15). The odds of hepatic steatosis increased by 15% for each SD increase in the maximum drinks per week (OR 1.15; 95% CI 1.02, 1.30). In the beverage specific analysis, alcohol use patterns were associated with hepatic steatosis among beer drinkers, but no significant associations were observed among wine drinkers. Conclusions: Even after excluding heavy alcohol users from our sample, alcohol use contributed to liver fat, which suggests alcohol-related liver fat may be present among individuals presumed to have NAFLD. Additional prospective studies are needed to validate our findings and to determine if more comprehensive alcohol use screening tools should be used in practice or clinical trial settings. / 2020-06-03T00:00:00Z

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19964号 / 医博第4154号 / 新制||医||1017(附属図書館) / 33060 / 京都大学大学院医学研究科医学専攻 / (主査)教授 柳田 素子, 教授 横出 正之, 教授 渡邊 直樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

O balanço energético corporal é mantido através de alterações na ingestão de calorias e no gasto energético. O prolongado balanço energético positivo, em que a ingestão excede o gasto, promove obesidade. A obesidade resulta do aumento de triacilglicerois no tecido adiposo, que também passa a apresentar inflamação de baixo grau crônica. O resultado disso envolve a redução da capacidade de tamponamento dos ácidos graxos livres circulantes e subsequente deposição de gordura em territórios ectópicos como musculatura esquelética e fígado, além de aumentar o risco de desenvolver o diabetes Mellitus tipo 2. Assim, a obesidade é um fator de risco importante para doenças metabólicas e suas comorbidades, dentre elas a doença gordurosa hepática não alcoólica. Uma proposta terapêutica para intervir na obesidade e/ou nas comorbidades associadas é o uso de substancias com ação anti-inflamatória. Considerando a possibilidade de novo uso para alguns produtos liberados para uso e com potencial tóxico já avaliado, foi escolhido avaliar o efeito do fitoterápico Uncaria tomentosa. Para isso, foram utilizados dois modelos de camundongos: (1) obesidade induzida por dieta hiperlipídica (DH), camundongos machos c57bl/6, alimentado com DH por 10 semanas, e (2) camundongo geneticamente obeso, ob/ob. A dose e tempo de tratamento escolhidos basearam-se no resultado da tolerância à insulina determinada inicialmente. Os animais receberam via oral o extrato da UT na dose de 50 mg/kg, uma vez ao dia, por 5 dias consecutivos. Seguindo-se ao tratamento, os animais foram submetidos a testes de tolerância a glicose e insulina, análise do coeficiente respiratório e depois a eutanásia, para retirada do fígado e sangue. O tecido hepático foi submetido a técnicas histológicas para verificar a morfologia e quantificação das gotículas de gordura, extração das proteínas celulares e RNAm para realização de western blot típico e reação em cadeia da polimerase (PCR), respectivamente. Também foi utilizada imunohistoquímica com anticorpo anti-F4/80 para comprovar infiltrado inflamatório. O tratamento com UT reduziu a glicemia de jejum cerca de 15 e 20% nos modelos DH e ob/ob, respectivamente, e a insulimenia para 54% no grupo DH, enquanto no grupo ob/ob houve um aumento de 2 vezes na insulinemia com o uso da UT. Houve uma redução de 22% no índice de massa corpórea (IMC) acompanhada de maior gasto energético com o tratamento no modelo DH. A esteatose hepática foi reduzida em aproximadamente 30% e a presença de infiltrados inflamatórios em 70% em ambos os modelos. Além disso, o grau de fosforilação do IRS1 no resíduo serina foi reduzido em 25% nos camundongos alimentados com DH após tratamento com UT, acompanhando a maior sensibilidade à insulina desses animais em relação aos obesos não tratados. Diante desses resultados, concluímos que o extrato bruto da Uncaria tomentosa melhora a homeostase da glicose e reverte a esteatohepatite incipiente a estatose benigna. O tratamento com Uncaria tomentosa pode ser uma estratégia terapêutica potencial no combate a alterações metabólicas associadas à obesidade como a doença hepática gordurosa não alcoólica (DHGNA) de início imediato. / The body\'s energy balance is maintained through changes in calorie intake and energy expenditure. The prolonged positive energy balance, in which the intake exceeds the expense, promotes obesity. Obesity results from the increase of triacylglycerols in adipose tissue, which also starts to present chronic low-grade inflammation. The result of this involves the reduction of the buffering capacity of circulating free fatty acids and subsequent fat deposition in ectopic territories such as skeletal muscle and liver, as well as increasing the risk of developing type 2 diabetes mellitus. Thus, obesity is an important risk factor for metabolic diseases and their comorbidities, among them non-alcoholic fatty liver disease. A therapeutic proposal to intervene in obesity and/or associated comorbidities is the use of substances with anti-inflammatory action. Considering the possibility of new use for some products released for use and with toxic potential already evaluated, it was chosen to evaluate the effect of the herbal remedy Uncaria tomentosa (UT), popularly known as cat\'s claw. Two models of mice were used: (1) higt fat diet induced obesity (HFD), male mice c57bl / 6, fed HFD for 12 weeks, and (2) genetically obese mice, ob/ob. The dose and time of treatment chosen were based on the initially determined insulin tolerance result. The animals received orally the UT extract at the dose of 50 mg/kg once daily for 5 consecutive days. Following the treatment, the animals were submitted to glucose and insulin tolerance tests, analysis of the respiratory coefficient and then euthanasia, for removal of the liver and blood. Liver tissue was submitted to histological techniques to verify the morphology and quantification of fat droplets, extraction of cellular proteins and mRNA for typical western blot and polymerase chain reaction (PCR), respectively. Immunohistochemistry with anti-F4 / 80 antibody was also used to prove inflammatory infiltrate. Treatment with UT reduced fasting glucose by 15 and 20% in the HFD and ob/ob models respectively, and the insukinemia to 54% in the HFD group, whereas in the ob/ob group there was a 2-fold increase in insulinemia with the use of UT. There was a 22% reduction in body mass index (BMI) accompanied by greater energy expenditure with HFD treatment. Hepatic steatosis was reduced by approximately 30% and the presence of inflammatory infiltrates by 70% in both models. In addition, the degree of IRS1 phosphorylation at the serine residue was reduced by 25% in the mice fed HFD after treatment with UT, following the higher insulin sensitivity of these animals compared to the untreated obese. In view of these results, we conclude that the crude extract of Uncaria tomentosa improves glucose homeostasis and reverts incipient steatohepatitis to benign steatosis. Treatment with Uncaria tomentosa can be a potential therapeutic strategy in the action against obesity-related metabolic alterations such as non-alcoholic fatty liver disease (NAFLD).

Introdução: A doença hepática alcóolica (DHA) e a doença hepática gordurosa não alcóolica (DHGNA) estão entre as principais causas de morte por doenças hepáticas no mundo. Apesar das etiologias distintas, sendo a DHA causada pelo consumo excessivo de álcool e a DHGNA por dieta inadequada e sedentarismo, apresentam curso de doença semelhante, que pode evoluir de esteatose, para esteato-hepatite, fibrose, cirrose e carcinoma hepatocelular. Tanto a DHA quanto a DHGNA estão relacionadas à disbiose, aumento de permeabilidade intestinal, inflamação e dano hepático. Entretanto, ainda não está claro se a doença hepática precede as alterações no epitélio intestinal ou se é o aumento da permeabilidade que promove o dano hepático. Objetivo: Avaliar a expressão gênica de Tight Junctions em modelo de DHA e DHGNA em zebrafish (Danio rerio). Métodos: No modelo de DHA, os peixes foram divididos em dois grupos: Etanol (n=30), expostos a 0,5% de etanol por 28 dias e controle (n=30). No modelo de DHGNA, os peixes foram divididos também em dois grupos: Frutose (n=24), expostos à frutose 6% durante 2 horas por 14 dias e controle (n=24). Ao término dos experimentos os animais foram eutanasiados e coletados fígados, para avaliação histológica por coloração hematoxilina-eosina (HE) e de esteatose por Oil Red, e intestinos para avaliação da expressão gênica dos marcadores de permeabilidade intestinal cldnC, cldn15a, cldn15b e f11r por Real Time qPcr. Resultados: Tanto os animais expostos ao álcool quanto à frutose apresentaram esteatose hepática por coloração HE e Oil Red quando comparados aos seus respectivos controles, sem sinais de infiltrados inflamatórios e de fibrose hepática à microscopia óptica. Não houve diferença significativa na expressão gênica das tight junctions intestinais, tanto para a DHA quanto DHGNA (p  0,05). Conclusão: Os resultados sugerem que em estágios iniciais de DHA e DHGNA não ocorre alteração da permeabilidade intestinal, e que possivelmente o dano hepático precede o dano intestinal. / Introduction: Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are among the leading causes of death from liver disease worldwide. Despite the different etiologies, ALD is caused by excessive alcohol consumption and NAFLD is due to inadequate diet and sedentary lifestyle, they have a similar disease course, which can progress from steatosis to steatohepatitis, fibrosis, cirrhosis and hepatocellular carcinoma. Both ALD and NAFLD are related to dysbiosis, increased gut permeability, inflammation, and liver damage. However, it is not yet clear whether liver disease precedes changes in the intestinal epithelium or whether it is the increased permeability that promotes liver damage. Objective: To evaluate the gene expression of tight junctions in ALD and NAFLD models in zebrafish (Danio rerio). Methods: In the ALD model, fish were divided into two groups: Ethanol (n=30), exposed to 0.5% ethanol for 28 days and control (n=30). In the NAFLD model, fish were also divided into two groups: Fructose (n=24), exposed to 6% fructose for 2 hours for 14 days and control (n=24). At the end of the experiments the animals were euthanized and livers were collected for histological evaluation by hematoxylin-eosin (HE) staining and steatosis by oil red staining and intestines for evaluation of the gene expression of gut permeability markers cldnC, cldn15a, cldn15b and f11r by Real Time qPcr. Results: Both animals exposed to alcohol and fructose presented hepatic steatosis by HE and Oil Red staining when compared to their respective controls, without signs of inflammatory infiltrates under optical microscopy. There was no significant difference in the gene expression of the tight junctions for both ALD and NAFLD (p0.05) Conclusion: The results suggest that in the early stages of ALD and NAFLD there are no changes in intestinal tight junctions, and that possibly liver damage precedes intestinal damage.