Nicotinamide Prevents Diabetic Brain Inflammation via NAD+-Dependent Deacetylation Mechanisms.

This study investigated the effect of nicotinamide (NAM) supplementation on the development of brain inflammation and microglial activation in a mouse model of type 1 diabetes mellitus. C57BL/6J male mice, which were made diabetic with five consecutive, low-dose (55 mg/kg i.p.) streptozotocin (STZ) injections. Diabetic mice were randomly distributed in different experimental groups and challenged to different doses of NAM (untreated, NAM low-dose, LD, 0.1%; NAM high-dose, HD, 0.25%) for 25 days. A control, non-diabetic group of mice was used as a reference. The NAD+ content was increased in the brains of NAM-treated mice compared with untreated diabetic mice (NAM LD: 3-fold; NAM HD: 3-fold, p-value < 0.05). Immunohistochemical staining revealed that markers of inflammation (TNFα: NAM LD: -35%; NAM HD: -46%; p-value < 0.05) and microglial activation (IBA-1: NAM LD: -29%; NAM HD: -50%; p-value < 0.05; BDKRB1: NAM LD: -36%; NAM HD: -37%; p-value < 0.05) in brains from NAM-treated diabetic mice were significantly decreased compared with non-treated T1D mice. This finding was accompanied by a concomitant alleviation of nuclear NFκB (p65) signaling in treated diabetic mice (NFκB (p65): NAM LD: -38%; NAM HD: -53%, p-value < 0.05). Notably, the acetylated form of the nuclear NFκB (p65) was significantly decreased in the brains of NAM-treated, diabetic mice (NAM LD: -48%; NAM HD: -63%, p-value < 0.05) and inversely correlated with NAD+ content (r = -0.50, p-value = 0.03), suggesting increased activity of NAD+-dependent deacetylases in the brains of treated mice. Thus, dietary NAM supplementation in diabetic T1D mice prevented brain inflammation via NAD+-dependent deacetylation mechanisms, suggesting an increased action of sirtuin signaling.

NAD+ Precursors and Intestinal Inflammation: Therapeutic Insights Involving Gut Microbiota.

The oxidized form of nicotinamide adenine dinucleotide (NAD+) is a critical metabolite for living cells. NAD+ may act either as a cofactor for many cellular reactions as well as a coenzyme for different NAD+-consuming enzymes involved in the physiological homeostasis of different organs and systems. In mammals, NAD+ is synthesized from either tryptophan or other vitamin B3 intermediates that act as NAD+ precursors. Recent research suggests that NAD+ precursors play a crucial role in maintaining the integrity of the gut barrier. Indeed, its deficiency has been associated with enhanced gut inflammation and leakage, and dysbiosis. Conversely, NAD+-increasing therapies may confer protection against intestinal inflammation in experimental conditions and human patients, with accumulating evidence indicating that such favorable effects could be, at least in part, mediated by concomitant changes in the composition of intestinal microbiota. However, the mechanisms by which NAD+-based treatments affect the microbiota are still poorly understood. In this context, we have focused specifically on the impact of NAD+ deficiency on intestinal inflammation and dysbiosis in animal and human models. We have further explored the relationship between NAD+ and improved host intestinal metabolism and immunity and the composition of microbiota in vivo. Overall, this comprehensive review aims to provide a new perspective on the effect of NAD+-increasing strategies on host intestinal physiology.

The Bittersweet Beat: Diabetes Complications.

In this Editorial, we are focusing on a selection of articles recently published in the Journal of Clinical Medicine dealing with relevant aspects of cardiometabolic complications of diabetes mellitus [...].

Fatty Acid Binding Proteins 3 and 4 Predict Both All-Cause and Cardiovascular Mortality in Subjects with Chronic Heart Failure and Type 2 Diabetes Mellitus.

Subjects with type 2 diabetes mellitus (T2D) are at increased risk for heart failure (HF). The cardiac-specific (FABP3) and adipose-tissue-specific (FABP4) types of the fatty acid binding proteins have been associated with both all-cause and cardiovascular (CV) mortality. The aim of this study was to explore the prognosis value of FABP3 and FABP4 in ambulatory subjects with chronic HF (CHF), with and without T2D. A prospective study involving 240 ambulatory CHF subjects was performed. Patients were followed-up for a mean of 5.78 ± 3.30 years and cause of death (if any) was recorded. Primary endpoints were defined as all-cause and CV death, and a composite endpoint that included CV death or hospitalization for HF was included as a secondary endpoint. Baseline serum samples were obtained and the serum FABP3 and FABP4 concentrations were assessed by sandwich enzyme-linked immunosorbent assay. Survival analysis was performed with multivariable Cox regressions, using Fine and Gray competing risks models when needed, to explore the prognostic value of FABP3 and FABP4 concentrations, adjusting for potential confounders. Type 2 diabetes mellitus was highly prevalent, accounting for 47.5% for total subjects with CHF. Subjects with T2D showed higher mortality rates (T2D: 69.30%; non-T2D: 50.79%, p = 0.004) and higher serum FABP3 (1829.3 (1104.9-3440.5) pg/mL vs. 1396.05 (820.3-2362.16) pg/mL, p = 0.007) and FABP4 (45.5 (27.6-79.8) ng/mL vs. 34.1 (24.09-55.3) ng/mL, p = 0.006) concentrations compared with non-T2D CHF subjects. In the whole study cohort, FABP3 was independently associated with all-cause death, and both FABP3 and FABP4 concentrations were associated with CV mortality. The predictive values of these two molecules for all-cause (FABP3: HR 1.25, 95% CI 1.09-1.44; p = 0.002. FABP4: HR 2.21, 95% CI 1.12-4.36; p = 0.023) and CV mortality (FABP3: HR 1.28, 95% CI 1.09-1.50; p = 0.002. FABP4: HR 4.19, 95% CI 2.21-7.95; p < 0.001) were only statistically significant in the subgroup of subjects with T2D. Notably, FABP4 (HR 2.07, 95% CI 1.11-3.87; p = 0.022), but not FABP3, also predicted the occurrence of the composite endpoint (death or hospitalization for HF) only in subjects with T2D. All these associations were not found in CHF subjects without T2D. Our findings support the usefulness of serum FABP3 and FABP4 concentrations as independent predictors for the occurrence of all-cause and CV mortality in ambulatory subjects with CHF with T2D.

Predictive Value of the Advanced Lipoprotein Profile and Glycated Proteins on Diabetic Retinopathy.

This study aimed to assess whether the advanced characteristics of serum lipoprotein subclasses could better predict the risk of developing diabetic retinopathy (DR) and its severity compared to other established risk factors in subjects with type 1 (T1D) and type 2 (T2D) diabetes. This observational, cross-sectional substudy analyzed DR-related data from 309 T1D and 264 T2D subjects. The advanced lipoprotein and glycoprotein profile was determined by nuclear magnetic resonance (NMR) spectroscopy (Liposcale test). NMR analysis of lipoproteins revealed that T1D subjects with DR showed standard non-HDL particles, despite higher IDL lipid concentrations. Notably, IDL lipids were elevated in T1D subjects with worsened DR. VLDL and LDL were smaller, whereas HDL triglycerides were increased in DR compared with non-DR. On the other hand, the T2D subjects with DR showed altered characteristics in the LDL fraction, mainly revealed by a significant decrease in smaller LDL and a reduction in LDL-C. Moreover, the glycoprotein profile did not reveal significant changes among DR groups, regardless of the type of diabetes. However, lipoprotein characteristics and glycoproteins unveiled by NMR analysis did not improve the predictive value of conventional lipids or other traditional, well-established biomarkers of DR in our cohorts.

Association of α-klotho with subclinical carotid atherosclerosis in subjects with type 1 diabetes mellitus.

BACKGROUND: Compelling evidence suggests that the fibroblast growth factor 23 (FGF23) / α-klotho axis is impaired in subjects with diabetes mellitus. We examined the relationship between parameters related to calcium/phosphate homeostasis, including FGF23 and α-klotho, and subclinical carotid atherosclerosis burden in type 1 diabetes mellitus (T1D) subjects. METHODS: This cross-sectional study involved 226 subjects with T1D and 147 age-, sex- and plaque-matched, non-diabetic (non-T1D) subjects, both with normal renal function. Carotid ultrasound was performed to determine the presence and burden of atheromatous plaques. Concentrations of the intact form of FGF23 and α-klotho were assessed by ELISA. Calcium, phosphate, parathyroid hormone, and vitamin D levels were also determined. Negative binomial regression models were used to examine relationship between parameters studied and subclinical carotid atherosclerosis. RESULTS: Only FGF23 was increased in T1D compared with non-diabetic subjects (> 2-fold; p < 0.05). α-klotho was higher in subjects with subclinical carotid atherosclerosis (1.4-fold, p < 0.05). Regression analysis revealed that the log α-klotho concentration was positively associated with the presence of subclinical carotid atherosclerosis both in T1D subjects (incidence rate ratio [IRR]: 1.41; 95% confidence interval [CI], 1.06-1.89; p < 0.05) and in non-T1D subjects (IRR: 1.65; 95% CI, 1.02-2.75; p < 0.05). The models also showed that age, smoking and albuminuria-to-creatinine ratio were positively associated with subclinical carotid atherosclerosis in T1D subjects. Interestingly, sex-related protection against plaque was also revealed in T1D women. CONCLUSION: Higher α-klotho was associated with subclinical carotid atherosclerotic in the absence of kidney dysfunction. This finding also points to a new pathophysiological pathway involved in the development and progression of this complication.

Diet change affects intestinal microbiota restoration and improves vertical sleeve gastrectomy outcome in diet-induced obese rats.

PURPOSE: Obesity, a worldwide health problem, is linked to an abnormal gut microbiota and is currently most effectively treated by bariatric surgery. Our aim was to characterize the microbiota of high-fat fed Sprague-Dawley rats when subjected to bariatric surgery (i.e., vertical sleeve gastrectomy) and posterior refeeding with either a high-fat or control diet. We hypothesized that bariatric surgery followed by the control diet was more effective in reverting the microbiota modifications caused by the high-fat diet when compared to either of the two factors alone. METHODS: Using next-generation sequencing of ribosomal RNA amplicons, we analyzed and compared the composition of the cecal microbiota after vertical sleeve gastrectomy with control groups representing non-operated rats, control fed, high-fat fed, and post-operative diet-switched animals. Rats were fed either a high-fat or control low-fat diet and were separated into three comparison groups after eight weeks comprising no surgery, sham surgery, and vertical sleeve gastrectomy. Half of the rats were then moved from the HFD to the control diet. Using next-generation sequencing of ribosomal RNA amplicons, we analyzed the composition of the cecal microbiota of rats allocated to the vertical sleeve gastrectomy group and compared it to that of the non-surgical, control fed, high-fat fed, and post-operative diet-switched groups. Additionally, we correlated different biological parameters with the genera exhibiting the highest variation in abundance between the groups. RESULTS: The high-fat diet was the strongest driver of altered taxonomic composition, relative microbial abundance, and diversity in the cecum. These effects were partially reversed in the diet-switched cohort, especially when combined with sleeve gastrectomy, resulting in increased diversity and shifting relative abundances. Several highly-affected genera were correlated with obesity-related parameters. CONCLUSIONS: The dysbiotic state caused by high-fat diet was improved by the change to the lower fat, higher fiber control diet. Bariatric surgery contributed significantly and additively to the diet in restoring microbiome diversity and complexity. These results highlight the importance of dietary intervention following bariatric surgery for improved restoration of cecal diversity, as neither surgery nor change of diet alone had the same effects as when combined.

Seasonal variation in plasma lipids and lipases in young healthy humans.

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year. In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am. Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude). Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter. These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.

Diet Change After Sleeve Gastrectomy Is More Effective for Weight Loss Than Surgery Only.

BACKGROUND: Bariatric surgery with or without diet change has become one of the most effective treatments for obesity. The objective of this study was to observe the effects of vertical sleeve gastrectomy (VSG) and diet change in Sprague-Dawley rats on both body and tissue weights. METHODS: Eighteen rats were fed with a standard chow diet (SCD) (C group), and 36 rats were fed with a high-fat diet (HFD) (diet-induced obesity (DIO) group). After 8 weeks, the animals underwent VSG, sham surgery or no surgery (NS). After surgery, a third of the rats fed with the HFD changed to the SCD (DIO + C group). Body weight, food and energy intake were recorded daily during the experiment (12 weeks). Food efficiency (%) (FE) was determined from weekly weight gain and weekly kilocalorie consumed measurements. RESULTS: The DIO group had higher and significant weight gain than the C group at the time of surgery (p < 0.001). The major weight loss (WL) was observed in the DIO + C-VSG group, during the 4 weeks after surgery. Adipose tissues in the DIO + C-VSG group were drastically reduced and had a weight similar to those in the C-VSG group. CONCLUSION: VSG and the diet change combination led to a greater WL, which was maintained during the 4 weeks post-surgery, leading to a normalization of body weight. VSG and diet change also affected most of the tissues, not only adipose, showing a global change in whole body composition.

Diabetic and dyslipidaemic morbidly obese exhibit more liver alterations compared with healthy morbidly obese.

BACKGROUND & AIMS: To study the origin of fat excess in the livers of morbidly obese (MO) individuals, we analysed lipids and lipases in both plasma and liver and genes involved in lipid transport, or related with, in that organ. METHODS: Thirty-two MO patients were grouped according to the absence (healthy: DM - DL -) or presence of comorbidities (dyslipidemic: DM - DL +; or dyslipidemic with type 2 diabetes: DM + DL +) before and one year after gastric bypass. RESULTS: The livers of healthy, DL and DM patients contained more lipids (9.8, 9.5 and 13.7 times, respectively) than those of control subjects. The genes implicated in liver lipid uptake, including HL, LPL, VLDLr, and FAT/CD36, showed increased expression compared with the controls. The expression of genes involved in lipid-related processes outside of the liver, such as apoB, PPARα and PGC1α, CYP7a1 and HMGCR, was reduced in these patients compared with the controls. PAI1 and TNFα gene expression in the diabetic livers was increased compared with the other obese groups and control group. Increased steatosis and fibrosis were also noted in the MO individuals. CONCLUSIONS: Hepatic lipid parameters in MO patients change based on their comorbidities. The gene expression and lipid levels after bariatric surgery were less prominent in the diabetic patients. Lipid receptor overexpression could enable the liver to capture circulating lipids, thus favouring the steatosis typically observed in diabetic and dyslipidaemic MO individuals.

Hepatic and visceral adipose tissue 11ßHSD1 expressions are markers of body weight loss after bariatric surgery.

OBJECTIVE: Cortisolemia and 11ßHSD1 in liver and adipose tissue are altered in obesity. However, their participation in the development of obesity remains unclear. This study analyzed these parameters in the transition from morbid to type 1 obesity after bariatric surgery. METHODS: A group of 34 patients with morbid obesity and 22 nonobese subjects were recruited. Initial hypothalamus-pituitary-adrenal (HPA) basal activity and 11ßHSD1 mRNA expression in liver, subcutaneous (SAT), and visceral adipose tissue (VAT) were evaluated. A year after bariatric surgery (weight loss of 48 kg), these parameters were reappraised in plasma, SAT, and liver. RESULTS: Body weight loss was accompanied by a downshift in basal HPA activity and 11ßHSD1 expression in SAT. In patients with morbid obesity, 11ßHSD1 expression correlated positively with BMI in VAT and negatively in liver at 6 and 12 months after surgery. In SAT, a correlation was observed with body weight only when patients showed type 1 obesity. Insulin, glucose, and HOMA correlated positively with all the HPA indicators and 11ßHSD1 expression in SAT. CONCLUSIONS: Body weight loss after bariatric surgery is accompanied by a downshift in basal HPA activity. Hepatic and VAT 11ßHSD1 expressions in morbid obesity are predictors of body weight loss.

Haematological parameters and serum trace elements in "healthy" and "unhealthy" morbidly obese patients before and after gastric bypass.

BACKGROUND & AIMS: We have investigated the differences in plasma parameters and serum trace elements between "healthy" and unhealthy morbidly obese patients before and after Roux-en-Y gastric bypass surgery. METHODS: A group of 32 morbidly obese patients undergoing bariatric surgery were divided into three groups. Group 1 subjects were free of dyslipidemia and type II diabetes mellitus (defined as "healthy" obese, DM-DL-); Group 2 subjects had only the presence of dyslipidemia (DM-DL+), while group 3 patients demonstrated the presence of both (DM + DL+). In all patients, we studied haematological, haemostasis, anaemia, coagulation plasma and trace elements parameters before and 1, 6 and 12 months after gastric bypass surgery. RESULTS: We found significant differences in some haematological parameters, including haemostasis (e.g., T-Quick, p = 0.0048) and coagulation (e.g., ATIII and PAI-1, p = 0.001 and p < 0.0001, respectively) and in anaemia parameters (e.g., folate, cobalamin and transferrin, p = 0.0002, p < 0.0001 and p = 0.0001, respectively) but also in serum trace elements between the groups. However, the response to bariatric surgery was similar in the three groups. CONCLUSION: Any healthy morbid obese subject is really metabolically "unhealthy" because he or she has many other haematologic or serum abnormalities that are often not included in the criteria for the definition of "healthy" in these obese subjects.

Morbidly "Healthy" Obese Are Not Metabolically Healthy but Less Metabolically Imbalanced Than Those with Type 2 Diabetes or Dyslipidemia.

BACKGROUND: We have investigated the differences between metabolically "healthy" morbidly obese patients and those with comorbidities. MATERIALS AND METHODS: Thirty-two morbidly obese patients were divided by the absence ("healthy": DM-DL-) or presence of comorbidities (dyslipidemic: DM-DL+, or dyslipidemic and with type 2 diabetes: DM+DL+). We have studied various plasma parameters and gene expression adipose tissue, before and after gastric bypass. RESULTS: The group DM+DL+ tends to have lower values than the other two groups for anthropometric parameters. Regarding the satiety parameters, only leptin (p = 0.0024) showed a significant increase with comorbidities. Lipid parameters showed significant differences among groups, except for phospholipids and NEFA. For insulin resistance parameters, only glucose (p < 0.0001) was higher in DM+DL+ patients, but not insulin or homeostasis model assessment of insulin resistance (HOMA-IR). The gene expression of adiponectin, insulin receptor (INSR) and glucose receptor-4 (GLUT4), in the subcutaneous fat, decreased in all groups vs. a non-obese control. Interleukin-6 (IL6) and the inhibitor of plasminogen activator type 1 (PAI-1) genes decreased only in DM-DL+ and DM+DL+, but not in "healthy" patients. Leptin increased in all groups vs. the non-obese control. The visceral fat from DM+DL+ patients showed a sharp decrease in adiponectin, GLUT4, IL6 and PAI-1. All parameters mentioned above improved very significantly by surgery, independent of the occurrence of comorbidities. CONCLUSIONS: The morbidly obese "healthy" individual is not really metabolically healthy, but morbidly obese individuals with diabetes and dyslipidemia are more metabolically imbalanced.

Decreased lipases and fatty acid and glycerol transporter could explain reduced fat in diabetic morbidly obese.

OBJECTIVE: The possible differences were investigated in 32 morbidly obese patients depending on whether they were "healthy" or had dyslipidemia and/or type 2 diabetes. METHODS: Lipid metabolism and insulin resistance were analyzed in subcutaneous (SAT) and visceral adipose tissue (VAT) before and during 6 and 12 months after Roux-en-Y gastric bypass. RESULTS: Significant differences have been found in lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) activities in SAT from the different obese group versus normal weight (control) but not between them. The reduced lipase activities in VAT were 43 and 19% smaller (22 and 4% smaller, respectively, vs. control) than the "healthy" obese group for LPL and HSL, respectively, and were accompanied with a reduced expression of these lipases, as well as decreased expression of FAT/CD36, FABP4, and AQ7 in that tissue. In addition, the expression of the other genes measured showed a downregulation not only versus the "healthy" obese but also versus the normal weight group. CONCLUSIONS: Being obese is not "healthy," but it is even less so if morbidly obese patients with diabetes and dyslipidemia were considered. The reduced fat accumulation in these patients may be attributed to the decrease of the expression and activity of the lipases of their adipose tissue.

Bariatric surgery in morbidly obese patients improves the atherogenic qualitative properties of the plasma lipoproteins.

OBJECTIVE: The purpose of this study was to evaluate the effect of weight loss induced in morbidly obese subjects by Roux-en-Y gastric bypass bariatric surgery on the atherogenic features of their plasma lipoproteins. METHODS: Twenty-one morbidly obese subjects undergoing bariatric surgery were followed up for up to 1 year after surgery. Plasma and lipoproteins were assayed for chemical composition and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Lipoprotein size was assessed by non-denaturing polyacrylamide gradient gel electrophoresis, and oxidised LDL by ELISA. Liver samples were assayed for mRNA abundance of oxidative markers. RESULTS: Lipid profile analysis revealed a reduction in the plasma concentrations of cholesterol and triglycerides, which were mainly associated with a significant reduction in the plasma concentration of circulating apoB-containing lipoproteins rather than with changes in their relative chemical composition. All patients displayed a pattern A phenotype of LDL subfractions and a relative increase in the antiatherogenic plasma HDL-2 subfraction (>2-fold; P < 0.001). The switch towards predominantly larger HDL particles was due to an increase in their relative cholesteryl ester content. Excess weight loss also led to a significant decrease in the plasma concentration of oxidised LDL (∼-25%; P < 0.01) and in the total Lp-PLA2 activity. Interestingly, the decrease in plasma Lp-PLA2 was mainly attributed to a decrease in the apoB-containing lipoprotein-bound Lp-PLA2. CONCLUSION: Our data indicate that the weight loss induced by bariatric surgery ameliorates the atherogenicity of plasma lipoproteins by reducing the apoB-containing Lp-PLA2 activity and oxidised LDL, as well as increasing the HDL-2 subfraction.