Metabolic Effects Of Duodenojejunal Bypass Surgery In A Rat Model Of Type 1 Diabetes

Background Metabolic surgery has beneficial metabolic effects, including remission of type 2 diabetes. We hypothesized that duodenojejunal bypass (DJB) surgery can protect against development of type 1 diabetes (T1D) by enhancing regulation of cellular and molecular pathways that control glucose homeostasis. Methods BBDP/Wor rats, which are prone to develop spontaneous autoimmune T1D, underwent loop DJB (n = 15) or sham (n = 15) surgery at a median age of 41 days, before development of diabetes. At T1D diagnosis, a subcutaneous insulin pellet was implanted, oral glucose tolerance test was performed 21 days later, and tissues were collected 25 days after onset of T1D. Pancreas and liver tissues were assessed by histology and RT-qPCR. Fecal microbiota composition was analyzed by 16S V4 sequencing. Results Postoperatively, DJB rats weighed less than sham rats (287.8 vs 329.9 g,P = 0.04). In both groups, 14 of 15 rats developed T1D, at similar age of onset (87 days in DJB vs 81 days in sham,P = 0.17). There was no difference in oral glucose tolerance, fasting and stimulated plasma insulin and c-peptide levels, and immunohistochemical analysis of insulin-positive cells in the pancreas. DJB rats needed 1.3 +/- 0.4 insulin implants vs 1.9 +/- 0.5 in sham rats (P = 0.002). Fasting and glucose stimulated glucagon-like peptide 1 (GLP-1) secretion was elevated after DJB surgery. DJB rats had reduced markers of metabolic stress in liver. After DJB, the fecal microbiome changed significantly, including increases inAkkermansiaandRuminococcus, while the changes were minimal in sham rats. Conclusion DJB does not protect against autoimmune T1D in BBDP/Wor rats, but reduces the need for exogenous insulin and facilitates other metabolic benefits including weight loss, increased GLP-1 secretion, reduced hepatic stress, and altered gut microbiome

STE20 kinase TAOK3 regulates type 2 immunity and metabolism in obesity

Healthy adipose tissue (AT) contains ST2(+) Tregs, ILC2s, and alternatively activated macrophages that are lost in mice or humans on high caloric diet. Understanding how this form of type 2 immunity is regulated could improve treatment of obesity. The STE20 kinase Thousand And One amino acid Kinase-3 (TAOK3) has been linked to obesity in mice and humans, but its precise function is unknown. We found that ST2(+) Tregs are upregulated in visceral epididymal white AT (eWAT) of Taok3(-/-) mice, dependent on IL-33 and the kinase activity of TAOK3. Upon high fat diet feeding, metabolic dysfunction was attenuated in Taok3(-/-) mice. ST2(+) Tregs disappeared from eWAT in obese wild-type mice, but this was not the case in Taok3(-/-) mice. Mechanistically, AT Taok3(-/-) Tregs were intrinsically more responsive to IL-33, through higher expression of ST2, and expressed more PPAR & gamma; and type 2 cytokines. Thus, TAOK3 inhibits adipose tissue Tregs and regulates immunometabolism under excessive caloric intake. Maes et al. reveal an unexpected role of TAOK3 in regulating ST2(+) regulatory T cells in mouse adipose tissue. Absence of TAOK3 sustains Tregs in obesity and improves metabolic dysfunction

Fat induces glucose metabolism in nontransformed liver cells and promotes liver tumorigenesis

Hepatic fat accumulation is associated with diabetes and hepatocellular carcinoma (HCC). Here, we characterize the metabolic response that high-fat availability elicits in livers before disease development. After a short term on a high-fat diet (HFD), otherwise healthy mice showed elevated hepatic glucose uptake and increased glucose contribution to serine and pyruvate carboxylase activity compared with control diet (CD) mice. This glucose phenotype occurred independently from transcriptional or proteomic programming, which identifies increased peroxisomal and lipid metabolism pathways. HFD-fed mice exhibited increased lactate production when challenged with glucose. Consistently, administration of an oral glucose bolus to healthy individuals revealed a correlation between waist circumference and lactate secretion in a human cohort. In vitro, palmitate exposure stimulated production of reactive oxygen species and subsequent glucose uptake and lactate secretion in hepatocytes and liver cancer cells. Furthermore, HFD enhanced the formation of HCC compared with CD in mice exposed to a hepatic carcinogen. Regardless of the dietary background, all murine tumors showed similar alterations in glucose metabolism to those identified in fat exposed nontransformed mouse livers, however, particular lipid species were elevated in HFD tumor and nontumor-bearing HFD liver tissue. These findings suggest that fat can induce glucose-mediated metabolic changes in nontransformed liver cells similar to those found in HCC

Interrogation of the perturbed gut microbiota in gouty arthritis patients through in silico metabolic modeling

Recent studies have shown perturbed gut microbiota associated with gouty arthritis, a metabolic disease characterized by an imbalance between uric acid production and excretion. To mechanistically investigate altered microbiota metabolism associated with gout disease, 16S rRNA gene amplicon sequence data from stool samples of gout patients and healthy controls were computationally analyzed through bacterial community metabolic models. Patient-specific community models constructed with the metagenomics modeling pipeline, mgPipe, were used to perform k-means clustering of samples according to their metabolic capabilities. The clustering analysis generated statistically significant partitioning of samples into a Bacteroides-dominated, high gout cluster and a Faecalibacterium-elevated, low gout cluster. The high gout cluster was predicted to allow elevated synthesis of the amino acids D-alanine and L-alanine and byproducts of branched-chain amino acid catabolism, while the low gout cluster allowed higher production of butyrate, the sulfur-containing amino acids L-cysteine and L-methionine, and the L-cysteine catabolic product H2S. By expanding the capabilities of mgPipe to provide taxa-level resolution of metabolite exchange rates, acetate, D-lactate and succinate exchanged from Bacteroides to Faecalibacterium were predicted to enhance butyrate production in the low gout cluster. Model predictions suggested that sulfur-containing amino acid metabolism generally and H2S more specifically could be novel gout disease markers

The role of diet in development and reversal of type 2 diabetes

Type 2 diabetes is a chronic disease, characterized by insulin resistance and beta-cell dysfunction. It is thought to be a consequence of both genetic predisposition and environmental factors. Although sedentary lifestyle and Western diet are the main drivers of the rising prevalence of type 2 diabetes, environmental pollutants have been reported to play a role as well. In the first part of this thesis, we evaluated the role of the cereulide toxin in beta cell failure and the onset of type 2 diabetes, as cereulide had been implicated in beta-cell toxicity and it had been found frequently in low concentrations in starchy dishes in Belgian restaurants. We confirmed the increased sensitivity to cereulide of different beta-cell models when compared to other mammalian cell lines. Rat and mouse beta-cell lines (INS-1E and MIN6) and freshly isolated murine pancreatic islets showed very high rates of apoptosis after exposure to 5 ng/ml cereulide for 24 h, whereas human hepatocellular carcinoma (HepG2) and renal fibroblast cells (COS-1) remained viable when exposed to the same concentration. Hoechst/propidium Iodide staining and electron microscopy evaluation revealed that the observed cell death was mainly due to apoptosis, which was further supported by increased caspase 3/7 activation, elevated cytochrome C release into the cytoplasm and upregulation of pro-apoptotic mRNA markers in MIN6 cells. Transmission electron microscopy showed that mitochondria of the MIN6 cells were swollen and disintegrated after exposure to 0.5 ng/ml cereulide. At this dose, reactive oxygen species culminated more than twofold, and basal respiration rate was reduced to half, as compared to unexposed MIN6 cells. Presumably, such high mitochondrial toxicity explains the reduced insulin secretion by MIN6 cells or whole mouse islets after cereulide exposure.Taken together, we show that cereulide causes apoptotic beta-cell death at low concentrations and impairs beta-cell function at even lower concentrations, with mitochondrial dysfunction underlying these defects. In the second part of the thesis, we investigated the impact of Roux-en-Y Gastric Bypass (RYGB) on pancreatic islet mass and function in a mouse model. Diet-induced obese C57BL/6J mice underwent RYGB or sham surgery at the age of 22 weeks. Postoperatively, the mice consumed the same high fat diet (HFD) as before, and sham mice were either pair-fed (PFS) or weight-matched (WMS) to the RYGB mice and compared to age-matched normal chow fed LEAN control mice. PFS mice regained body weight quickly after sham surgery to become obese and glucose intolerant by the end of the 8 week postsurgical follow-up period. RYGB and WMS on the other hand, had a similar body weight and body fat percentage as LEAN mice. Total energy expenditure was higher in RYGB compared to WMS mice. In vitro glucose stimulated insulin secretion was not significantly altered in isolated islets after RYGB, compatible with the hypothesis that changes in the gastrointestinal tract are necessary for the RYGB-specific observed effects on beta-cell function. Histological examination showed similar islet numbers in LEAN, WMS, RYGB and PFS mice. However, islets of PFS mice were larger than islets of LEAN mice. Interestingly, the islet size in RYGB and WMS also tended to be larger than in LEAN mice. We speculate that the islet size increased during the high fat feeding that rendered the mice obese. Subsequently, islet partial involution occurs when weight is lost by either RYGB or caloric restriction. We did not detect differences in islet composition, in particular in terms of relative insulin content, between experimental groups. Ki67-staining showed very low proliferation of islet cells in all groups, as can be expected in 30 week old mice at steady state. Pathway analysis of the RYGB islet transcriptome suggested no difference in inflammation or endoplasmic reticulum stress in islets post-RYGB compared to WMS mice. However, several proliferation/differentiation markers were upregulated in islets following RYGB and most members of the Reg gene family were expressed in the pancreases of the RYGB but not the WMS mice. Overexpression of Reg2 and Reg3b in MIN6 cells line, did not affect the insulin secretion. As no difference in proliferation was noted in the histology samples, the relevance of the Reg gene upregulation in islets after RYGB remains to be determined and will be subject of further research. In this chapter, we concluded that islet histology, function and gene profile did not differ dramatically between the mice that underwent RYGB or lost similar weight by caloric restriction. In the third part of the thesis we investigated the metabolic impact after different weight loss strategies. Twenty two weeks old diet-induced obese C57BL/6J mice underwent RYGB-HF or caloric restriction on either normal chow (RESTR-NC) or HFD (RESTR-HF), in order to attain a similar body weight as the LEAN control mice on normal chow at the end of the 8 weeks intervention period. Thirty weeks old HFD fed mice were used as age-matched OBESE controls. Oxygen consumption, heat production and total energy expenditure decreased with weight loss through adaptive thermogenesis and there was no significant difference between RESTR-NC and RESTR-HF mice. The epididymal white adipose tissue (eWAT) pads and individual adipocytes of the RESTR-HF mice were significantly larger than in RESTR-NC and RYGB-HF mice. The adipocytes in RESTR-NC mice were not enlarged anymore, and the increased density compared to NC-CO mice suggests that adipocyte size rather than number is affected by weight loss. In addition, mRNA markers of inflammation were at normal levels in RESTR-NC and RYGB-HF mice, but were increased in the eWAT of OBESE mice and RESTR-HF mice. Both histological examination and triglyceride (TG) content evaluation of hepatic tissues showed massive steatosis in all OBESE mice, but also signs of steatosis in RESTR-HF and RYGB-HF mice, while RESTR-NC and LEAN were free of fatty liver disease. The eWAT size and hepatic TG content was tightly correlated with the glucose and insulin tolerance tests. Actually, the intraperitoneal glucose tolerance tests revealed that the RESTR-HF mice were only slighty less glucose intolerant than the OBESE mice, despite a major weight loss. If the same weight loss was achieved on a normal chow diet on the other hand (RESTR-NC) or by RYGB the glucose tolerance was restored. Thus, we clearly show that metabolic improvement is not solely weight driven. We demonstrate that shifting to lower fat foods has a greater metabolic benefit than losing weight by restricting calories or surgery without modifications of the food content. Food with lower fat content causes less fat disposition and by consequence less glucose intolerance than weight loss achieved through restriction on fat. The overall conclusion of the present thesis is that external pollutants can contribute to type 2 diabetes by direct detrimental effects on beta-cell survival and function and that the nature of weight loss strategies matters by its impact on fat disposition and insulin resistance, but has no direct effect on beta-cells.status: publishe

Role of Microbiome and Antibiotics in Autoimmune Diseases

The global rise in the incidence of autoimmune diseases has paralleled the widespread use of antibiotics. Recently, the gut microbiome has been shown to be key in the development and maturation of a normal immune system, and a range of microbial disturbances have been associated with the development and activity of several autoimmune diseases. Here, we aim to provide an overview of the mechanistic crosstalk between the human microbiome, the immune system, and antibiotics. The disease-associated microbial gut dysbiosis, the potential role of antibiotics in the development and treatment of autoimmune diseases, and the manipulation of the gut microbiome with prebiotics and probiotics is discussed using 2 key autoimmune diseases as an example: inflammatory bowel disease and type 1 diabetes. Although some data suggest that widespread use of antibiotics may facilitate autoimmunity through gut dysbiosis, there are also data to suggest antibiotics may hold the potential to improve disease activity. Currently, the effect of fecal microbiota transplantation on several autoimmune diseases is being studied in clinical trials, and several preclinical studies are revealing promising results with probiotic and prebiotic therapies.status: publishe

Routine gynecological ultrasound: look at the bladder and the ureters!

Background: To illustrate the technical feasibility and diagnostic value of including the assessment of the bladder and the ureters during a standard transvaginal ultrasound examination. Methods: We present four cases illustrating ureter and bladder pathology diagnosed by transvaginal ultrasound. Results: In a first case, transvaginal ultrasonography in a woman with lower abdominal pain showed a calculus in the left distal ureter. The small echogenic lesion was easily detectable within the ureter lumen. A second patient, presenting with suprapubic pain, urgency and back pain, was also diagnosed with a ureteral calculus and additionally a hydroureter. The presence of a hydroureter is part of the differential diagnosis of any cystic structure in the pelvis. In a third case, an elderly woman, referred with uterine prolapse, transvaginal ultrasound examination showed a tubular anechoic structure lateral in the pelvis due to a hydroureter, illustrating the differential diagnosis with a hydrosalpinx. A fourth patient, presenting with hematuria, showed an irregular and highly vascularized mass in the bladder and was diagnosed with a transitional cell carcinoma. Conclusion: The bladder and pelvic part of the ureters are easily identifiable on transvaginal scan. Important pathology of the lower urinary tract and the distal ureters can be readily diagnosed by transvaginal ultrasound examination. The evaluation of the bladder and the ureters should therefore be part of the standard gynecological ultrasound investigation.status: Published onlin

ApoB in de lipidenkliniek, waarom en wanneer meten?

status: publishe