Macrophage activation plays a crucial role in regulating adipose tissue inflammation and is a major contributor to the pathogenesis of obesity-associated cardiovascular diseases. On various types of stimuli, macrophages respond with either classic (M1) or alternative (M2) activation. M1- and M2-mediated signaling pathways and corresponding cytokine production profiles are not completely understood. The discovery of microRNAs provides a new opportunity to understand this complicated but crucial network for macrophage activation and adipose tissue function. We have examined the activity of microRNA-223 (miR-223) and its role in controlling macrophage functions in adipose tissue inflammation and systemic insulinresistance. miR-223-/- mice on a high-fat diet exhibited an increased severity of systemic insulin resistance compared with wild-type mice that was accompanied by a marked increase in adipose tissue inflammation. The specific regulatory effects of miR-223 in myeloid cell-mediated regulation of adipose tissue inflammation and insulin resistance were then confirmed by transplantation analysis. Moreover, using bone marrow-derived macrophages, we demonstrated that miR-223 is a novel regulator of macrophage polarization, which suppresses classic pro-inflammatory pathways and enhances the alternative anti-inflammatory responses. In addition, we identified Pknox1 as a genuine miR-223 target gene and an essential regulator for macrophage polarization. For the first time, this study demonstrates that miR-223 acts to inhibit Pknox 1,suppressing pro-inflammatory activation of macrophages; thus, it is a crucial regulator of macrophage polarization and protects against diet-induced adipose tissue inflammatory response and systemic insulin resistance.

The overall aim of the work presented in this thesis was to further characterise aspects of metabolic and immune system cross-talk in human subcutaneous adipose tissue, with a particular emphasis on the potential role of T-lymphocytes in adipose tissue dysfunction and insulin resistance. Chapter 3 characterised macrophage and T-lymphocyte populations residing in adipose tissue from lean through to class I obese men. This work demonstrated that T-lymphocytes display increased activation with increased adiposity and that potential compensatory mechanisms may be present to help counteract adipose tissue inflammation. In Chapter 4, the same participants were exposed to a meal-based stimulus in order to examine the postprandial metabolic and inflammatory responses in blood and adipose tissue. Despite increased glucose and insulin responses in blood with obesity, there were no differences in inflammatory cytokine gene expression responses in adipose tissue. This suggests that mechanisms may be present to limit or dampen inflammatory output from adipose tissue after feeding in individuals with modestly increased adiposity. Chapter 5 examined metabolic and immune system changes to 50 % calorie restriction for 3 days, resulting in reduced serum leptin which was temporally associated with a reduction in blood T-lymphocyte activation. In adipose tissue, however, leptin gene expression/secretion was not reduced and neither was resident T-lymphocyte activation, indicating that there may be local tissue-specific responses of immune cells to caloric restriction. Chapter 6 characterised differences between obese individuals with either normal or impaired glucose tolerance, and their respective responses to 10 days of diet and activity modification. Overall, this thesis highlights key differences in properties of T-lymphocyte populations with increasing levels of adiposity and insulin resistance together with responses in adipose tissue and the immune system in times of feeding, severe calorie restriction and glucose lowering diet and activity.

A inibição de mTOR com rapamicina exacerba a intolerância glicose associada a obesidade, um efeito que pode estar associado ao desenvolvimento de processo pró-inflamatório no tecido adiposo. O tratamento de camundongos com rapamicina exacerbou a intolerância a glicose e inflamação do tecido adiposo induzida por dieta hiperlipídica. In vitro, a inibição dos complexos 1 e 2 da mTOR com rapamicina e torina induziu polarização espontânea de macrófagos para o fenótipo M1 e aumentou a atividade fagocítica de macrófagos M0. Camundongos com ativação constitutiva de mTORC1 exclusivamente em células mielóides foram protegidos do ganho de peso, adiposidade, intolerância a glicose e a insulina induzidos pela ingestão de dieta hiperlipídica e apresentaram um aumento da polarização de macrófagos para o fenótipo M2. Em conjunto, nossos dados indicam que a atividade do complexo 1 da mTOR atenua o desenvolvimento da inflamação do tecido adiposo associada a obesidade por um mecanismo que envolve a polarização de macrófagos para o fenótipo M2. / Pharmacological mTOR inhibition with rapamycin exacerbates the glucose intolerance associated with obesity, such an effect that may be associated to the development of inflammatory process in adipose tissue. Rapamycin treatment exacerbates the glucose intolerance and adipose tissue inflammation induced by high fat diet feeding. In vitro, inhibition of mTOR complexes 1 and 2 with rapamycin and torin induced spontaneous macrophage polarization into a pro-inflammatory M1 phenotype and increased M0 macrophage phagocytosis. Mice with constitutive activation of mTOR complex 1 in myeloid cells were protected from body weight gain, fat accretion, glucose and insulin tolerance induced by the intake of high fat diet and displayed a significant increase in macrophage polarization to a M2 phenotype. Altogether, our findings indicate that the activity of mTOR complex 1 attenuates the development of adipose tissue inflammation induced by high fat feeding, through a mechanism that involves a higher polarization of macrophages to anti-inflammatory M2 phenotype.

A inibição de mTOR com rapamicina exacerba a intolerância glicose associada a obesidade, um efeito que pode estar associado ao desenvolvimento de processo pró-inflamatório no tecido adiposo. O tratamento de camundongos com rapamicina exacerbou a intolerância a glicose e inflamação do tecido adiposo induzida por dieta hiperlipídica. In vitro, a inibição dos complexos 1 e 2 da mTOR com rapamicina e torina induziu polarização espontânea de macrófagos para o fenótipo M1 e aumentou a atividade fagocítica de macrófagos M0. Camundongos com ativação constitutiva de mTORC1 exclusivamente em células mielóides foram protegidos do ganho de peso, adiposidade, intolerância a glicose e a insulina induzidos pela ingestão de dieta hiperlipídica e apresentaram um aumento da polarização de macrófagos para o fenótipo M2. Em conjunto, nossos dados indicam que a atividade do complexo 1 da mTOR atenua o desenvolvimento da inflamação do tecido adiposo associada a obesidade por um mecanismo que envolve a polarização de macrófagos para o fenótipo M2. / Pharmacological mTOR inhibition with rapamycin exacerbates the glucose intolerance associated with obesity, such an effect that may be associated to the development of inflammatory process in adipose tissue. Rapamycin treatment exacerbates the glucose intolerance and adipose tissue inflammation induced by high fat diet feeding. In vitro, inhibition of mTOR complexes 1 and 2 with rapamycin and torin induced spontaneous macrophage polarization into a pro-inflammatory M1 phenotype and increased M0 macrophage phagocytosis. Mice with constitutive activation of mTOR complex 1 in myeloid cells were protected from body weight gain, fat accretion, glucose and insulin tolerance induced by the intake of high fat diet and displayed a significant increase in macrophage polarization to a M2 phenotype. Altogether, our findings indicate that the activity of mTOR complex 1 attenuates the development of adipose tissue inflammation induced by high fat feeding, through a mechanism that involves a higher polarization of macrophages to anti-inflammatory M2 phenotype.

Obesity and associated metabolic disorders, e. g. metabolic syndrome, represent a considerable health threat for modern society. Due to sedentary lifestyle, high caloric intake and changes in composition of diet, prevalence of obesity is increasing worldwide. One of the possible causes contributing to higher prevalence of obesity in recent population could be the change of fatty acids (FA) composition of dietary lipids, with the shift in the content of n-6 and n-3 FA toward n-6 FA. In contrast to n-6 FA, n-3 FA are known for their anti-atherogenic, anti-obesogenic and anti-inflammatory properties. In our experiments in mice, the capability of naturally occurred and chemically modified n- 3 long chain polyunsaturated fatty acids (LC-PUFA) in prevention and reversal of specific parts of metabolic syndrome was demonstrated. A specific chemical derivative of docosahexaenoic acid was proven to be very effective in preventing and improving metabolic conditions of animals exposed to high-fat (HF) diet challenge. Further, the involvement of AMP-activated protein kinase (AMPK), a master regulator of lipid metabolism, in skeletal muscle thermogenesis induced by HF-feeding was investigated. Activation of AMPK in the HF-fed mice is most possibly caused by increased leptin levels and represents an important link...

Obesity and associated metabolic disorders, e. g. metabolic syndrome, represent a considerable health threat for modern society. Due to sedentary lifestyle, high caloric intake and changes in composition of diet, prevalence of obesity is increasing worldwide. One of the possible causes contributing to higher prevalence of obesity in recent population could be the change of fatty acids (FA) composition of dietary lipids, with the shift in the content of n-6 and n-3 FA toward n-6 FA. In contrast to n-6 FA, n-3 FA are known for their anti-atherogenic, anti-obesogenic and anti-inflammatory properties. In our experiments in mice, the capability of naturally occurred and chemically modified n- 3 long chain polyunsaturated fatty acids (LC-PUFA) in prevention and reversal of specific parts of metabolic syndrome was demonstrated. A specific chemical derivative of docosahexaenoic acid was proven to be very effective in preventing and improving metabolic conditions of animals exposed to high-fat (HF) diet challenge. Further, the involvement of AMP-activated protein kinase (AMPK), a master regulator of lipid metabolism, in skeletal muscle thermogenesis induced by HF-feeding was investigated. Activation of AMPK in the HF-fed mice is most possibly caused by increased leptin levels and represents an important link...

No description available.

O consumo de ácidos graxos n-3 tem sido associado à proteção contra a obesidade, inflamação e resistência à insulina. Os n-3 são ligantes fracos dos receptores nucleares PPARγ, e pela ativação deste podem exercer suas ações metabólicas e anti-inflamatórias. No presente trabalho, foi investigado se o aumento da disponibilidade dos n-3 geneticamente ou por dieta, via ativação de PPARγ, protege camundongos do desenvolvimento da obesidade, intolerância a glicose e inflamação do tecido adiposo. Foi visto em um modelo com camundongos fat-1 (elevados níveis endógenos de n-3) que dentre as ações dos ácidos graxos n-3, a proteção contra o aumento de peso/adiposidade associada à obesidade, bem como a melhora da intolerância à glicose são dependentes de PPARγ. Além disso, por meio da utilização de camundongos com deleção de PPARγ em hepatócitos os dados desse trabalho mostram que os PPARγ são, ao menos em parte, essenciais ao aumento da oxidação de ácidos graxos induzida pelos n-3 devido à modulação da expressão gênica e protéica de enzimas mitocondriais e peroxissomais. / The intake of n-3 fatty acids have been associated to the protection against obesity, inflammation and insulin resistance. The n-3 fatty acids are ligands of the nuclear receptor PPARγ, and by the activation of this receptor can promote their metabolic and anti-inflammatory effects. Herein, we investigated whether increasing body n-3 fatty acids levels either genetically or by a n-3 enriched diet protects mice from diet-induced obesity, glucose intolerance and adipose tissue inflammation through PPARγ activation. Fat-1 mice were protected from diet-induced obesity, glucose intolerance and adipose tissue inflammation. To better investigate PPARγ involvement in n-3 beneficial actions, mice with genetic deletion of PPARγ specifically in hepatocytes. In spite of the absence of changes in body weight and glucose homeostasis PPARγ deletion in hepatocytes completely abolished the increase in liver fatty acid oxidation and hepatic gene expression of genes associated to mitochondrial and peroxisomal activity.

<p>Познато је да гојазност представља фактор ризика за развој карцинома дојке након менопаузе, док су подаци који се односе на репродуктивни периоду опречни. Познато је да је масно ткиво гојазних подложно хроничној инфламацији ниског степена и развоју оксидативног стреса. Ове промене су знатно боље испитане у висцералном масном ткиву у контексту развоја кардиометаболичких компликација, док је њихова улога у карциногенези мање позната. Циљ истраживања била је анализа масе и дистрибуције масног ткива пременопаузалних жена оболелих од карцинома дојке, као и показатеља инфламаторних промена и оксидативног стреса у масном ткиву дојке у односу на степен ухрањености. Истраживањем је обухваћено 50 пременопаузалних жена оболелих од карцинома дојке, 97 жена са бенигним променама у дојци и 209 здравих жена различитог степена ухрањености. Резултати нашег испитивања показали су да жене оболеле од карцинома дојке, посебно оне које су нормално ухрањене, имају већу склоност ка централној депозицији масног ткива. Уочена је значајно већа активност и експресија антиоксидативних ензима, како у жлезданом, тако и у масном ткиву дојке код жена оболелих од карцинома дојке у односу на контролну групу жена са бенигним променама, док је у односу на степен ухрањености примећена статистички значајно већа активност и експресија параметара редокс регулације код нормално ухрањених жена. Са друге стране, наши резултати не показују значајне разлике у степену експресије инфламаторних маркера TNF&alpha; и IL-6 у масном и жлезданом ткиву у односу на степен ухрањености, нити у односу на тип промена у дојци. Присуство макрофага класе М1 уочено је само у масном ткиву, док је присуство макрофага класе М2 детектовано у масном и жлезданом ткиву код жена са бенигним променама. Резултати анализе степена пролиферације туморских ћелија (ki67) нису показали статистички значајне разлике у односу на степен ухрањености, нити у односу на начин дистрибуције масног ткива. Није запажена разлика у степену апоптозе међу испитиваним групама. Добијени резултати указују на повезаност централне депозиције масног ткива и карцинома дојке, корелацију промена у масном и туморском ткиву, као и на разлике у антиоксидативном одговору код жена различитог степена ухрањености.</p> / <p>Poznato je da gojaznost predstavlja faktor rizika za razvoj karcinoma dojke nakon menopauze, dok su podaci koji se odnose na reproduktivni periodu oprečni. Poznato je da je masno tkivo gojaznih podložno hroničnoj inflamaciji niskog stepena i razvoju oksidativnog stresa. Ove promene su znatno bolje ispitane u visceralnom masnom tkivu u kontekstu razvoja kardiometaboličkih komplikacija, dok je njihova uloga u karcinogenezi manje poznata. Cilj istraživanja bila je analiza mase i distribucije masnog tkiva premenopauzalnih žena obolelih od karcinoma dojke, kao i pokazatelja inflamatornih promena i oksidativnog stresa u masnom tkivu dojke u odnosu na stepen uhranjenosti. Istraživanjem je obuhvaćeno 50 premenopauzalnih žena obolelih od karcinoma dojke, 97 žena sa benignim promenama u dojci i 209 zdravih žena različitog stepena uhranjenosti. Rezultati našeg ispitivanja pokazali su da žene obolele od karcinoma dojke, posebno one koje su normalno uhranjene, imaju veću sklonost ka centralnoj depoziciji masnog tkiva. Uočena je značajno veća aktivnost i ekspresija antioksidativnih enzima, kako u žlezdanom, tako i u masnom tkivu dojke kod žena obolelih od karcinoma dojke u odnosu na kontrolnu grupu žena sa benignim promenama, dok je u odnosu na stepen uhranjenosti primećena statistički značajno veća aktivnost i ekspresija parametara redoks regulacije kod normalno uhranjenih žena. Sa druge strane, naši rezultati ne pokazuju značajne razlike u stepenu ekspresije inflamatornih markera TNF&alpha; i IL-6 u masnom i žlezdanom tkivu u odnosu na stepen uhranjenosti, niti u odnosu na tip promena u dojci. Prisustvo makrofaga klase M1 uočeno je samo u masnom tkivu, dok je prisustvo makrofaga klase M2 detektovano u masnom i žlezdanom tkivu kod žena sa benignim promenama. Rezultati analize stepena proliferacije tumorskih ćelija (ki67) nisu pokazali statistički značajne razlike u odnosu na stepen uhranjenosti, niti u odnosu na način distribucije masnog tkiva. Nije zapažena razlika u stepenu apoptoze među ispitivanim grupama. Dobijeni rezultati ukazuju na povezanost centralne depozicije masnog tkiva i karcinoma dojke, korelaciju promena u masnom i tumorskom tkivu, kao i na razlike u antioksidativnom odgovoru kod žena različitog stepena uhranjenosti.</p> / <p>It is well known that obesity is a risk factor for breast cancer development in postmenopausal women while the data referring to premenopausal women are inconsistent. It is well documented that adipose tissue in obesity is susceptible to the development of low grade chronic inflammation and oxidative stress. These changes are more studied in visceral adipose tissue related to cardiometabolic complications, while their roles in carcinogenesis is less established. The aim of the study was to analyse the body weight and adipose tissue distribution in premenopausal women with breast cancer as well as markers of inflammation and oxidative stress regarding to nutrition level. The study included 50 premenopausal women with breast cancer, 97 women with benign breast diseases and 209 healthy women of different nutrition level. The results of our study showed higher tendency of women with breast cancer, especially normal-weight, toward central fat deposition. Comparing to women with benign breast diseases, women with breast cancer had significantly higher activity and expression of antioxidant enzymes in both adipose and glandular breast tissue, while in relationship to nutrition level normal-weight women showed statistically significantly higher activity and expression of these enzymes. On the other hand, our results did not show significant differences in inflammatory markers TNF&alpha; and IL-6 in adipose and glandular breast tissue in relationship to nutrition level nor to the type of breast changes. The presence of M1 macrophages was noted only in adipose tissue, while M2 macrophages appeared in both adipose and glandular breast tissue of women with benign breast changes. Cell proliferation level (ki67) did not statistically differ between women of different nutrition level or adipose tissue distribution. No difference between apoptosis level was found among examined groups. These results indicate to the association between adipose tissue central deposition and breast cancer, correlation of changes in adipose and tumor tissue, as well as to the various antioxidative response related to nutrition level.</p>

O consumo de ácidos graxos n-3 tem sido associado à proteção contra a obesidade, inflamação e resistência à insulina. Os n-3 são ligantes fracos dos receptores nucleares PPAR&gamma;, e pela ativação deste podem exercer suas ações metabólicas e anti-inflamatórias. No presente trabalho, foi investigado se o aumento da disponibilidade dos n-3 geneticamente ou por dieta, via ativação de PPAR&gamma;, protege camundongos do desenvolvimento da obesidade, intolerância a glicose e inflamação do tecido adiposo. Foi visto em um modelo com camundongos fat-1 (elevados níveis endógenos de n-3) que dentre as ações dos ácidos graxos n-3, a proteção contra o aumento de peso/adiposidade associada à obesidade, bem como a melhora da intolerância à glicose são dependentes de PPAR&gamma;. Além disso, por meio da utilização de camundongos com deleção de PPAR&gamma; em hepatócitos os dados desse trabalho mostram que os PPAR&gamma; são, ao menos em parte, essenciais ao aumento da oxidação de ácidos graxos induzida pelos n-3 devido à modulação da expressão gênica e protéica de enzimas mitocondriais e peroxissomais. / The intake of n-3 fatty acids have been associated to the protection against obesity, inflammation and insulin resistance. The n-3 fatty acids are ligands of the nuclear receptor PPAR&gamma;, and by the activation of this receptor can promote their metabolic and anti-inflammatory effects. Herein, we investigated whether increasing body n-3 fatty acids levels either genetically or by a n-3 enriched diet protects mice from diet-induced obesity, glucose intolerance and adipose tissue inflammation through PPAR&gamma; activation. Fat-1 mice were protected from diet-induced obesity, glucose intolerance and adipose tissue inflammation. To better investigate PPAR&gamma; involvement in n-3 beneficial actions, mice with genetic deletion of PPAR&gamma; specifically in hepatocytes. In spite of the absence of changes in body weight and glucose homeostasis PPAR&gamma; deletion in hepatocytes completely abolished the increase in liver fatty acid oxidation and hepatic gene expression of genes associated to mitochondrial and peroxisomal activity.