Non-alcoholic fatty liver disease:understanding the role of aging, fatty acid transport and epigenetics

Overgewicht, een gezondheidstoestand waarbij de inname van energie groter is dan het verbruik ervan, vormt een wereldwijd probleem in de huidige maatschappij. De toename in overgewicht gaat gepaard met een stijging in overgewicht gerelateerde ziekten, zoals type 2 diabetes (T2D) en niet-alcoholische leververvetting (NAFLD). NAFLD is wereldwijd de grootste veroorzaker van leverziekte. Het begint met vet ophoping in de lever, beter bekend als lever steatose. Deze goedaardige en omkeerbare toestand van NAFLD kan echter uitgroeien tot een leverontsteking ofwel een niet-alcoholische steatohepatitis (NASH), welke vervolgens kan doorgroeien tot fibrose, cirrose en uiteindelijk een hepatocellulair carcinoom (HCC). Toch worden de pathogenese van NAFLD en de mechanismen, die verantwoordelijk zijn voor de progressie van de ziekte, onvoldoende begrepen. Het in dit proefschrift beschreven onderzoek werd uitgevoerd om meer inzicht te krijgen in de etiologie, het verloop van de ziekte en het effect van risicofactoren zoals ouderdom en laaggradige chronische ontsteking op de ontwikkeling van NAFLD. Daarnaast beschrijven we de rol van macroH2A1 en de vetzuurtransporteur CD36 in de ontwikkeling van NAFLD met behulp van diermodellen en een dieet interventiestrategie. Onze gegevens suggereren dat een breed spectrum van genetische en milieu afhankelijke factoren betrokken zijn bij de ontwikkeling van NAFLD. Echter meer onderzoek en begrip over deze factoren is vereist om de weg vrij te banen voor een nieuwe behandeling van NAFLD

Obesity-induced chronic inflammation in C57Bl6J mice, a novel risk factor in the progression of renal AA amyloidosis?

Background: Compelling evidence links obesity induced systemic inflammation to the development of chronic kidney disease (CKD). This systemic inflammation may result from exacerbated adipose inflammation. Besides the known detrimental effects of typical pro-inflammatory factors secreted by the adipose tissue (TNF-α, MCP-1 and IL-6) on the kidney, we hypothesize the enhanced obesity-induced secretion of serum amyloid A (SAA), an acute inflammatory protein, to play a key role in aggravating obesity-induced CKD. Methods: Groups of male C57Bl/6J mice (n = 99 in total) were fed a low (10% lard) or high (45% lard) fat diet for a maximum of 52 weeks. Mice were sacrificed after 24, 40 and 52 weeks. Whole blood samples, kidneys and adipose tissues were collected. The development of adipose and renal tissue inflammation was assessed on gene expression and protein level. Adipocytokine levels were measured in plasma samples. Results: A distinct inflammatory phenotype was observed in the adipose tissue of HFD mice prior to renal inflammation, which was associated with an early systemic elevation of TNF-α, leptin and SAA (1A-C). With aging, sclerotic lesions appeared in the kidney, the extent of which was severely aggravated by HFD feeding. Lesions exhibited typical amyloid characteristics (2A) and pathological severity positively correlated with bodyweight (2B). Interestingly, more SAA protein was detected in lesions of HFD mice. Conclusion: Our data suggest a causal link between obesity induced chronic inflammation and AA amyloidosis in C57Bl/6J mice. Though future studies are necessary to prove this causal link and to determine its relevance for the human situation, obesity may hence be considered a risk factor for the development and progression of renal AA amyloidosis in the course of CKD. (Figure Presented)

Предсказание торсионных углов в аминокислотных последовательностях белков на основе байесовской процедуры распознавания на цепях Маркова

Запропоновано процедуру розпізнавання торсіонних кутів, утворених C^α атомами чотирьох сусідніх амінокислотних залишків. Отримана послідовність кутів використовується для побудови просторової структури білка на решітці Z³.Torsion angles defined on C^α atoms of four neighbouring residues are predicted using Bayesian pattern recognition procedure on non-stationary Markov chains. The predicted sequence of torsion angles is used for constructing protein 3-dimensional structure on Z³

Plasticity of lifelong calorie-restricted C57BL/6J mice in adapting to a medium-fat diet intervention at old age

Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study we investigated the systemic and liver-specific responses caused by a diet switch to a medium-fat (MF) diet in 24-month-old life-long, CR-exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine-week-old C57BL/6J mice were exposed either to a control, CR or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitum MF feeding (CR-MF). The mice were sacrificed at the age of 28 months, then biochemical and molecular analyses were performed. Our results showed that, despite the long-term exposure to the CR regimen, mice in the CR-MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR-improved survival was observed in the diet switch group. The liver transcriptomic profile of CR-MF mice largely shifted to a profile similar to the MF-fed animals but leaving ~22% of the 1578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the life-long CR group. Therefore, although the diet switch was performed at an old age, the CR-MF-exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies

箸の文化と割箸の歴史地理：奈良吉野下市の割箸を主として

Lipid droplets (LDs) hypertrophy in adipocytes is the main cause of energy metabolic system dysfunction, obesity and its afflictions such as T2D. However, the role of adipocytes in linking energy metabolic disorders with insulin regulation is unknown in humans. Human adipocytes constitutively synthesize and secrete insulin, which is biologically functional. Insulin concentrations and release are fat mass-and LDs-dependent respectively. Fat reduction mediated by bariatric surgery repairs obesity-associated T2D the expression of genes, like PCSK1 (proinsulin conversion enzyme), GCG (Glucagon), GPLD1, CD38 and NNAT, involved in insulin regulation/release were differentially expressed in pancreas and adipose tissue (AT). INS (insulin) and GCG expression reduced in human AT-T2D as compared to AT-control, but remained unchanged in pancreas in either state. Insulin levels (mRNA/protein) were higher in AT derived from prediabetes BB rats with destructed pancreatic 2-cells and controls than pancreas derived from the same rats respectively. Insulin expression in 10 human primary cell types including adipocytes and macrophages is an evidence for extrapancreatic insulin-producing cells the data suggest a crosstalk between AT and pancreas to fine-tune energy metabolic system or may minimize the metabolic damage during diabetes. This study opens new avenues towards T2D therapy with a great impact on public health

Intermittent calorie restriction largely counteracts the adverse health effects of a moderate-fat diet in aging C57BL/6J mice

Scope: Calorie restriction (CR) has been shown to extend life- and health-span in model species. For most humans, a life-long CR diet is too arduous to adhere to. The aim of this study was to explore whether weekly intermittent CR can 1) provide long-term beneficial effects and 2) counteract diet-induced obesity in male aging mice. Methods and results: In this study we have exposed C57Bl/6J mice for 24 months to an intermittent (INT) diet, alternating weekly between CR of a control diet and ad libitum moderate-fat (MF) feeding. This weekly intermittent CR significantly counteracted the adverse effects of the MF diet on mortality, body weight and liver health markers in male 24-month-old mice. Hepatic gene expression profiles of INT-exposed animals appeared much more comparable to CR than to MF-exposed mice. At 12 months of age, a subgroup of MF-exposed mice was transferred to the INT diet. Gene expression profiles in the liver of the 24-month-old diet switch mice were highly similar to the INT-exposed mice. However, a small subset of genes was consistently changed by the MF diet during the first phase of life. Conclusion: Weekly intermittent CR largely, but not completely, reversed adverse effects caused by a MF diet