Increased Plasma Proneurotensin Levels Identify NAFLD in Adults With and Without Type 2 Diabetes

Proneurotensin/Neuromedin N and Risk of Incident CKD and Other Kidney Outcomes in Community-Living Individuals: The REGARDS Study

Rationale & Objective

Plasma proneurotensin/neuromedin N (pro-NT/NMN) is a precursor of neurotensin, a tridecapeptide linked with type 2 diabetes mellitus and other comorbid conditions associated with kidney disease. Whether pro-NT/NMN is directly associated with incident chronic kidney disease (CKD), and whether that association differs by race, is uncertain. We evaluated whether pro-NT/NMN levels were associated with increased risk of kidney outcomes.

Study Design

Prospective cohort.

Setting & Participants

Participants in Biomarker Mediators of Racial Disparities in Risk Factors, a nested cohort from the REasons for Geographic And Racial Differences in Stroke study, with available stored serum and urine samples from baseline and second visits for biomarker measurement.

Exposure

Baseline log-transformed pro-NT/NMN.

Outcomes

Incident CKD, progressive estimated glomerular filtration rate (eGFR) decline, incident albuminuria, and incident kidney failure within median follow-up time of 9.4 years.

Analytical Approach

Logistic regression.

Results

Among 3,914 participants, the mean ± SD age was 64 ± 8 (SD) years, 48% were women, and 51% were Black. Median baseline eGFR was 90 (IQR, 77-102) mL/min/1.73 m2. Each SD higher of pro-NT/NMN was associated with 9% higher odds of progressive eGFR decline (OR, 1.09; 95% CI, 1.00-1.20). There was no association observed with incident CKD (OR, 1.10; 95% CI, 0.96-1.27), incident albuminuria (OR, 1.08; 95% CI, 0.96-1.22), or incident kidney failure (OR, 1.10; 95% CI, 0.83-1.46). There were no differences in results by race or sex.

Limitations

Single measurement of pro-NT/NMN and limited generalizability.

Conclusions

Higher pro-NT/NMN was associated with progressive eGFR decline but no other manifestations of kidney disease incidence.

Reduced Lipopolysaccharide-Binding Protein (LBP) Levels Are Associated with Non-Alcoholic Fatty Liver Disease (NAFLD) and Adipose Inflammation in Human Obesity

Lipopolysaccharide (LPS) and its binding protein LBP have emerged as potential contributors to the progression from overweight/obesity to overt metabolic diseases and NAFLD. While LPS is known to activate hepatocyte inflammation, thus contributing toward NAFLD development, the role of LBP is more intricate, and recent data have shown that experimental reduction in hepatic LBP promotes NAFLD progression. In this cross-sectional investigation, we evaluated circulating LBP in relation to obesity, NAFLD, visceral adipose tissue (VAT) inflammation, and type 2 diabetes (T2D). We recruited 186 individuals (M/F: 81/105; age: 47 ± 10.4 years; BMI: 35.5 ± 8.6 kg/m2); a subgroup (n = 81) underwent bariatric surgery with intra-operative VAT and liver biopsies. LBP levels were higher in obese individuals than non-obese individuals but were inversely correlated with the parameters of glucose metabolism. Reduced LBP predicted T2D independent of age, sex, and BMI (p < 0.001). LBP levels decreased across more severe stages of hepatosteatosis and lobular inflammation, and were inversely associated with VAT inflammation signatures. In conclusion, LBP levels are increased in obese individuals and are associated with a more favorable metabolic profile and lower NAFLD/NASH prevalence. A possible explanation for these findings is that hepatic LBP production may be triggered by chronic caloric excess and facilitate LPS degradation in the liver, thus protecting these individuals from the metabolic consequences of obesity.

Higher circulating levels of proneurotensin are associated with increased risk of incident NAFLD

BACKGROUND

Neurotensin (NT), an intestinal peptide able to promote fat absorption, is implicated in the pathogenesis of obesity. Increased levels of proneurotensin (pro-NT), a stable NT precursor fragment, have been found in subjects with nonalcoholic fatty liver disease (NAFLD); however, whether higher pro-NT levels are associated with an increased NAFLD risk independently of other metabolic risk factors is unsettled.

METHODS

Ultrasound-defined presence of NAFLD was assessed on 303 subjects stratified into tertiles according to fasting pro-NT levels. The longitudinal association between pro-NT levels and NAFLD was explored on the study participants without NAFLD at baseline reexamined after 5 years of follow-up (n = 124).

RESULTS

Individuals with higher pro-NT levels exhibited increased adiposity, a worse lipid profile, and insulin sensitivity as compared to the lowest tertile of pro-NT. Prevalence of NAFLD was progressively increased in the intermediate and highest pro-NT tertile as compared to the lowest tertile. In a logistic regression analysis adjusted for several confounders, individuals with higher pro-NT levels displayed a raised risk of having NAFLD (OR = 3.43, 95%CI = 1.48-7.97, p = 0.004) than those in the lowest pro-NT tertile. Within the study cohort without NAFLD at baseline, subjects with newly diagnosed NAFLD at follow-up exhibited higher baseline pro-NT levels than those without incident NAFLD. In a cox hazard regression analysis model adjusted for anthropometric and metabolic parameters collected at baseline and follow-up visit, higher baseline pro-NT levels were associated with an increased risk of incident NAFLD (HR = 1.52, 95%CI = 1.017-2.282, p = 0.04).

CONCLUSION

Higher pro-NT levels are a predictor of NAFLD independent of other metabolic risk factors.

Cardiovascular Effects of Weight Loss in Obese Patients with Diabetes: Is Bariatric Surgery the Additional Arrow in the Quiver?

Obesity is an increasingly widespread disease worldwide because of lifestyle changes. It is associated with an increased risk of cardiovascular disease, primarily type 2 diabetes mellitus, with an increase in major cardiovascular adverse events. Bariatric surgery has been shown to be able to reduce the incidence of obesity-related cardiovascular disease and thus overall mortality. This result has been shown to be the result of hormonal and metabolic effects induced by post-surgical anatomical changes, with important effects on multiple hormonal and molecular axes that make this treatment more effective than conservative therapy in determining a marked improvement in the patient's cardiovascular risk profile. This review, therefore, aimed to examine the surgical techniques currently available and how these might be responsible not only for weight loss but also for metabolic improvement and cardiovascular benefits in patients undergoing such procedures.

Evaluating the Feasibility of Pro-Neurotensin and 25-Hydroxyvitamin D3 as Possible Indicators for Type 2 Diabetes Mellitus and Its Complications

(1) Background: Type 2 diabetes mellitus (T2DM) and metabolic syndrome are associated with decreased vitamin D. In contrast, high pro-neurotensin (pro-NT) levels are linked with an increased risk of T2DM and cardiovascular disease. We aimed to determine the validity of pro-NT and 25-dihydroxy vitamin D3 levels as predictors for T2DM complications; (2) Methods: One hundred T2DM, and one hundred healthy volunteers participated in this case-control study. Their Pro-NT and 25-hydroxyvitamin D3 levels were evaluated using the ELISA technique; (3) Results: Pro-NT and 25 (OH) vitamin D3 have significant validity and accuracy in T2DM prediction, 84.5%, and 90.5%, respectively (p = 0.001). At a value of <29.5, 25-Hydroxy vitamin D3 showed 88% sensitivity and 93% specificity in predicting T2DM. At a value of >124 Pmol/L, Pro-NT showed 81% sensitivity and 88% specificity in predicting T2DM. At a value of 16.5, 25-Hydroxy vitamin D3 had 78.4% sensitivity and 68.3% specificity in predicting T2DM complications. At a value of >158 pmol/L, Pro-NT predicted T2DM complications with 67.6% sensitivity and 56.0% specificity; (4) Conclusions: 25 (OH) Vit D3 and Pro-NT could identify T2DM patients and predict T2DM complications. More extensive research is required to adequately validate this novel perspective with a large population study.

Neurotensin Gene rs2234762 C>G Variant Associates with Reduced Circulating Pro-NT Levels and Predicts Lower Insulin Resistance in Overweight/Obese Children

Neurotensin (NT) is a small protein implicated in the regulation of energy balance which acts as both a neurotransmitter in the central nervous system and as a gastrointestinal peptide. In the gut, NT is secreted after fat ingestion and promotes the absorption of fatty acids. The circulating levels of its precursor, pro-NT, predicts the presence and development of metabolic and cardiovascular diseases. Despite the extensive knowledge on the dynamic changes that occur to pro-NT = after fat load, the determinants of fasting pro-NT are unknown. The aim of this study was to determine the possible genetic regulation of plasma pro-NT. The NT gene (NTS) was sequenced for potential functional variants, evaluating its entire genomic and potentially regulatory regions, in DNA from 28 individuals, stratified by low and high pro-NT levels. The identified variant differently distributed in the two pro-NT subgroups was genotyped in a cohort of nine hundred and thirty-two overweight/obese children and adolescents. A total of seven sequence variations across the NTS gene, none of them located in coding regions, were identified. The rs2234762 polymorphism, sited in the NTS gene promoter, was statistically more frequent in the lowest pro-NTS level group. Carriers of the rs2234762 variant showed lower pro-NT levels, after adjusting for sex, age, BMI, triglycerides and the Tanner stage. Having NTS rs2234762 predicted less pronounced insulin resistance at the 6.5-year follow-up with OR: 0.46 (0.216–0.983), at the logistic regression analysis adjusted for age, sex and BMI. In conclusion, the NTS rs2234762 gene variant is a determinant of reduced circulating pro-NT levels in overweight and obese children, which predisposes this group to a more favorable metabolic profile and a reduced insulin resistance later in life, independently from metabolic confounders.

Increased meal-induced neurotensin response predicts successful maintenance of weight loss - Data from a randomized controlled trial

BACKGROUND

The gut derived anorexigenic hormone neurotensin (NT) is upregulated after bariatric surgery which may contribute to the sustained weight loss. In contrast, diet-induced weight loss is most often followed by weight regain. We therefore investigated whether diet-induced weight loss impacts levels of circulating NT in mice and humans and whether NT levels predicts body weight change after weight loss in humans.

METHODS

In vivo mice study: Obese mice were fed ad-libitum or a restricted diet (40-60 % of average food intake) for 9 days to obtain similar weight loss as observed in the human study. At termination, intestinal segments, the hypothalamus and plasma were collected for histological, real time PCR, and radioimmunoassay (RIA) analysis.

CLINICAL TRIAL

Plasma samples from 42 participants with obesity, completing an 8-week low-calorie diet in a randomized controlled trial, were analyzed. Plasma NT was measured by RIA at fasting and during a meal test before and after diet-induced weight loss and after one year of intended weight maintenance.

RESULTS

In obese mice, food restriction-induced body weight loss of 14 % was associated with a 64 % reduction in fasting plasma NT (p < 0.0001). In the mouse duodenum (p = 0.07) and jejunum (p < 0.05), NT tissue concentration was decreased without tissue atrophy indicative of a physiological downregulation. In the mouse hypothalamus a downregulation of Pomc (p < 0.01) along with upregulation of Npy (p < 0.001) and Agrp (p < 0.0001) expression was found after restricted feeding in support of increased hunger after diet-induced weight loss. Therefore, we investigated the NT response in humans undergoing weight loss maintenance. In humans, similar to the mice, the low-calorie diet induced weight loss of 13 % body weight was associated with 40 % reduction in fasting plasma NT levels (p < 0.001). Meal-induced NT peak responses were greater in humans who lost additional weight during the 1 year maintenance phase compared to participants who regained weight (p < 0.05).

CONCLUSION

Diet-induced weight loss decreased fasting plasma NT levels in both humans and mice with obesity, and regulated hunger-associated hypothalamic gene expression in mice. Meal-induced NT responses were greater in humans who lost additional weight during the 1 year maintenance phase compared to participants who regained weight. This indicates that increased peak secretion of NT after weight loss may contribute to successful maintenance of weight loss.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02094183.

A study on serum pro-neurotensin (PNT), furin, and zinc alpha-2-glycoprotein (ZAG) levels in patients with acromegaly

PURPOSE

Acromegaly caused by growth hormone cell adenoma is commonly associated with abnormal glucolipid metabolism, which may result from changes in adipocytokine secretion. This study aims to investigate serum adipokine levels, including pro-neurotensin (PNT), furin, and zinc alpha-2-glycoprotein (ZAG), in acromegalic patients and the correlation between the levels of these three adipokines and GH levels and glucolipid metabolism indices.

METHODS

Sixty-eight acromegalic patients and 121 controls were included, and their clinical data were recorded from electronic medical record system. Serum PNT, furin and ZAG levels were measured by ELISA.

RESULTS

Serum PNT levels in acromegalic patients were significantly higher than controls (66.60 ± 12.36 vs. 46.68 ± 20.54 pg/ml, P < 0.001), and acromegaly was an independent influencing factor of PNT levels (P < 0.001). Moreover, subjects with the highest tertile of PNT levels had a close correlation with acromegaly (OR = 22.200, 95% CI 7.156 ~ 68.875, P < 0.001), even in Model 1 adjusted for gender and age and Model 2 adjusted for gender, age and BMI. Additionally, serum PNT levels were positively correlated with BMI (r = 0.220, P = 0.002) and triglycerides (TGs, r = 0.295, P < 0.001), and TGs were an independent influencing factor of serum PNT levels in acromegalic subjects (P < 0.001). Furthermore, serum PNT levels in obese acromegalic patients were significantly higher than those with normal BMI (P < 0.05). However, serum furin levels were lower in acromegalic patients than controls (0.184 ± 0.036 vs. 0.204 ± 0.061 ng/ml, P < 0.001).

CONCLUSION

This study is the first to demonstrate that acromegalic patients have increased serum PNT levels. Moreover, serum PNT plays a potential role in abnormal lipid metabolism of acromegalic patients.

Association between Metabolically Healthy Obesity and Subclinical Atherosclerosis in the Cardiovascular and Metabolic Diseases Etiology Research Center (CMERC) Cohort

We aimed to investigate the association between a new definition of metabolic health (MH) and subclinical atherosclerosis in a cohort of patients without previous cardiovascular disease (CVD). In total, 7824 community-dwelling adults were categorized as normal weight, overweight, or obese. Metabolically healthy obesity (MHO) was defined as obesity accompanied by all of the following criteria: systolic blood pressure (BP) < 130 mmHg, no use of BP-lowering medication, waist-hip ratio <0.832 (women) and <0.887 (men), and no prevalent diabetes. Carotid atherosclerosis was defined as carotid plaque or mean carotid intima-media thickness ≥ 1.1 mm. The prevalence of carotid atherosclerosis was 8.3% and 1113 (14.2%) patients were classified as having MHO. All individuals classified as metabolically unhealthy were at an increased risk of carotid atherosclerosis independent of body mass index categories. Conversely, the risk of carotid atherosclerosis in individuals with MHO was not significantly increased compared to that in metabolically healthy normal weight participants (hazard ratio 1.20, 95% confidence interval 0.87−1.67). This new definition of MH was able to identify people with MHO without an increased risk of CVD in an Asian community cohort.

Plasma Proneurotensin and Prediction of Cause-Specific Mortality in a Middle-aged Cohort During Long-term Follow-up

CONTEXT

Neurotensin is associated with cardiometabolic diseases but its role with mortality risk in humans is unknown.

OBJECTIVE

This work aims to examine the prediction of proneurotensin (Pro-NT) with respect to total and cause-specific mortality in a middle-aged cohort.

METHODS

In the population-based middle-aged cohort (n = 4632; mean age, 57 years) of the Malmö Diet and Cancer Study, Pro-NT was assessed and total as well as cause-specific mortality was studied. Main cause of death was based on the International Classification of Diseases.

RESULTS

During a mean follow-up of 20 ± 3 years, 950 men and 956 women died. There was significantly increased mortality risk in individuals belonging to the highest quartile (Q) of Pro-NT (Q4, Pro-NT ≥ 149 pmol/L) compared with Qs 1 to 3 (Pro-NT < 149 pmol/L), hazard ratio (HR), 95% CI of 1.29 (1.17-1.42; P < .001). Data were adjusted for sex and age. No significant interaction was observed between Pro-NT and sex on mortality risk. Individuals within Q4 vs Qs 1 to 3 had an HR of 1.41 (95% CI, 1.18-1.68; P < .001) for death due to cardiovascular disease (n = 595/4632); 2.53 (95% CI, 1.37-4.67; P = .003), due to digestive tract disease (n = 42/4632), 1.62 (95% CI, 1.04-2.52; P = .032) due to mental and behavioral disease (n = 90/4632); and 1.91 (95% CI, 1.15-3.19; P = .013) due to unspecific causes (n = 64/4632). There was no significant relationship between Pro-NT and deaths due to cancer, infections, neurological, or other causes. Adjustment for cardiovascular risk factors only marginally changed these results.

CONCLUSION

The relationship between Pro-NT and total mortality risk was mainly driven by cardiovascular mortality, but high Pro-NT also predicts death from digestive, mental, and behavioral disease and deaths attributed to unspecific causes.

New Insights in the Control of Fat Homeostasis: The Role of Neurotensin

Neurotensin (NT) is a small peptide with pleiotropic functions, exerting its primary actions by controlling food intake and energy balance. The first evidence of an involvement of NT in metabolism came from studies on the central nervous system and brain circuits, where NT acts as a neurotransmitter, producing different effects in relation to the specific region involved. Moreover, newer interesting chapters on peripheral NT and metabolism have emerged since the first studies on the NT-mediated regulation of gut lipid absorption and fat homeostasis. Intriguingly, NT enhances fat absorption from the gut lumen in the presence of food with a high fat content, and this action may explain the strong association between high circulating levels of pro-NT, the NT stable precursor, and the increased incidence of metabolic disorders, cardiovascular diseases, and cancer observed in large population studies. This review aims to provide a synthetic overview of the main regulatory effects of NT on several biological pathways, particularly those involving energy balance, and will focus on new evidence on the role of NT in controlling fat homeostasis, thus influencing the risk of unfavorable cardio–metabolic outcomes and overall mortality in humans.

High pro-neurotensin levels in individuals with type 1 diabetes associate with the development of cardiovascular risk factors at follow-up

AIMS

Neurotensin (NT) is a gut hormone that promotes lipids absorption and controls appetite. Elevated circulating pro-NT, the stable precursor of NT, is associated with cardiovascular (CV) disease, metabolic syndrome (MS) and type 2 diabetes (T2D). Features of MS and insulin resistance are reported also in type 1 diabetes (T1D), with detrimental impact on the overall CV risk profile. Aims of the study were to evaluate plasma pro-NT in T1D patients and to test whether its levels are associated with and/or predictive of CV risk factors and overall risk profile.

METHODS

For this longitudinal retrospective study, we analyzed clinical data from 41 T1D individuals referring to the diabetes outpatient clinics at Sapienza University of Rome, Italy, collected at the baseline and after 10 years. Fasting plasma pro-NT levels were measured in T1D subjects at the baseline and in 34 age-, sex-, BMI-comparable healthy individuals recruited in the same period.

RESULTS

Pro-NT did not differ significantly between patients and controls (median[range] pro-NT: 156.3 [96.6-198.2] vs. 179.4 [139.7-230.7] pmol/L, p = 0.26). In T1D, greater fasting pro-NT associated with poor glycemic control at baseline and predicted increased waist circumference, reduced insulin sensitivity, dyslipidemia and hypertension at 10-year follow-up. High pro-NT predicted 10-year very-high CV risk with adjusted OR = 11 (95%C.I.: 1.4-94.5; p = 0.029).

CONCLUSIONS

In T1D individuals, elevated pro-NT levels predict the development of adverse metabolic profile, which translates in higher CV risk profile at 10-year follow-up. Pro-NT represents a novel predictor/marker of CV risk factors in adults with T1D.

Pro-Neurotensin as a Potential Novel Diagnostic Biomarker for Detection of Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

Currently, liver biopsy is the gold standard method for diagnosis of non-alcoholic fatty liver severity. It is critical to develop non-invasive diagnostic method to diagnose nonalcoholic fatty liver rather than invasive techniques. Our case-control study was to address the value of circulating miRNA-122 and serum pro-neurotensin as a potential non-invasive biomarker for the diagnosis of non-alcoholic fatty acid diseases.

METHODS

Clinical assessment, laboratory investigations, and anthropometric measurements were reported for 157 patients with proven NAFLD. Apparently, healthy participants (n=100) were enrolled as a control group. Serum samples were tested for micro-RNAs-122 and pro-neurotensin.

RESULTS

Compared with the control subjects, both mi-RNA-122 and serum proneurotensin levels were increased in NAFLD (p<0.001) and at a cut-off ≥6.83, mi-RNA-122 had 51.0% sensitivity, 70.0% specificity to differentiate NAFLD from healthy controls, while serum proneurotensin had 80.0% sensitivity and 80.0% specificity at a cutoff ≥108.

CONCLUSION

The circulating pro-neurotensin might be used as a novel biomarker for diagnosis of patients with NAFLD, wherefore the integration of a circulating mi-RNA-122 and serum pro-neurotensin could be beneficial to diagnose NAFLD cases. Large-scale studies are needed to investigate the possible role of mi-RNA-122 and pro-neurotensin in the development, progression, and prognosis of NAFLD and NASH.

Effect of Bariatric Surgery on Metabolic Diseases and Underlying Mechanisms

Obesity is a highly prevalent public health concern, attributed to multifactorial causes and limited in treatment options. Several comorbidities are closely associated with obesity such as the development of type 2 diabetes mellitus (T2DM), cardiovascular and cerebrovascular diseases, and nonalcoholic fatty liver disease (NAFLD). Bariatric surgery, which can be delivered in multiple forms, has been remarked as an effective treatment to decrease the prevalence of obesity and its associated comorbidities. The different types of bariatric surgery create a variety of new pathways for food to metabolize in the body and truncate the stomach's caliber. As a result, only a small quantity of food is tolerated, and the body mass index noticeably decreases. This review describes the improvements of obesity and its comorbidities following bariatric surgery and their mechanism of improvement. Additionally, endocrine function improvements after bariatric surgery, which contributes to the patients' health improvement, are described, including the role of glucagon-like peptide-1 (GLP-1), fibroblast growth factors 19 and 21 (FGF-19, FGF-21), and pancreatic peptide YY (PYY). Lastly, some of the complications of bariatric surgery, including osteoporosis, iron deficiency/anemia, and diarrhea, as well as their potential mechanisms, are described.

Pro-Neurotensin/Neuromedin N and Risk of Incident Metabolic Syndrome and Diabetes Mellitus in the REGARDS Cohort

CONTEXT

The peptide neurotensin is implicated in insulin resistance, diabetes mellitus (DM), and cardiovascular disease.

OBJECTIVE

We studied the association of neurotensin's stable precursor, pro-neurotensin/neuromedin N (pro-NT/NMN) with incident metabolic syndrome (MetS) and DM.

METHODS

We included 3772 participants from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study who completed the baseline exam (2003-2007), the follow-up exam (2013-2016), and had pro-NT/NMN measured by immunoassay. Weighted logistic regression models were fitted to incident DM, incident MetS, and each MetS component, separately, incorporating demographics, metabolic risk factors, homeostasis model of insulin resistance (HOMA-IR), and diet scores. Incident MetS was defined by 3 or more harmonized criteria at follow-up in those with fewer than 3 at baseline. Incident DM was defined by use of hypoglycemic drugs/insulin, fasting glucose 126 mg/dL or greater, or random glucose 200 mg/dL or greater in those without these at baseline.

RESULTS

Median (IQR) plasma pro-NT/NMN was 160 pmol/L (118-218 pmol/L). A total of 564 (of 2770 without baseline MetS) participants developed MetS, and 407 (of 3030 without baseline DM) developed DM. Per SD higher log-pro-NT/NMN, the demographic-adjusted odds ratio (OR) and 95% CI of incident MetS was 1.22 (1.11-1.35), 1.16 (1.00-1.35) for incident low high-density lipoprotein (HDL), and 1.25 (1.11-1.40) for incident dysglycemia. The association of pro-NT/NMN with MetS was attenuated in the model adding HOMA-IR (OR per SD log-pro-NT/NMN 1.14; 95% CI, 1.00-1.30). There was no association with incident DM (OR per SD log-pro-NT/NMN 1.06; 95% CI, 0.94-1.19).

CONCLUSION

Pro-NT/NMN was associated with MetS and 2 components, dysglycemia and low HDL, likely explained by insulin resistance.

Neurotensin is an anti-thermogenic peptide produced by lymphatic endothelial cells

The lymphatic vasculature plays important roles in the physiology of the organs in which it resides, though a clear mechanistic understanding of how this crosstalk is mediated is lacking. Here, we performed single-cell transcriptional profiling of human and mouse adipose tissue and found that lymphatic endothelial cells highly express neurotensin (NTS/Nts). Nts expression is reduced by cold and norepinephrine in an α-adrenergic-dependent manner, suggesting a role in adipose thermogenesis. Indeed, NTS treatment of brown adipose tissue explants reduced expression of thermogenic genes. Furthermore, adenoviral-mediated overexpression and knockdown or knockout of NTS in vivo reduced and enhanced cold tolerance, respectively, an effect that is mediated by NTSR2 and ERK signaling. Inhibition of NTSR2 promoted energy expenditure and improved metabolic function in obese mice. These data establish a link between adipose tissue lymphatics and adipocytes with potential therapeutic implications.

Circulating Levels of Pro-Neurotensin and Its Relationship with Nonalcoholic Steatohepatitis and Hepatic Lipid Metabolism

Recent studies suggest a link between pro-neurotensin (pro-NT) and nonalcoholic fatty liver disease (NAFLD), but the published data are conflicting. Thus, we aimed to analyze pro-NT levels in women with morbid obesity (MO) and NAFLD to investigate if this molecule is involved in NAFLD and liver lipid metabolism. Plasma levels of pro-NT were determined in 56 subjects with MO and 18 with normal weight (NW). All patients with MO were subclassified according to their liver histology into the normal liver (NL, n = 20) and NAFLD (n = 36) groups. The NAFLD group had 17 subjects with simple steatosis (SS) and 19 with nonalcoholic steatohepatitis (NASH). We used a chemiluminescence sandwich immunoassay to quantify pro-NT in plasma and RT-qPCR to evaluate the hepatic mRNA levels of several lipid metabolism-related genes. We reported that pro-NT levels were significantly higher in MO with NAFLD than in MO without NAFLD. Additionally, pro-NT levels were higher in NASH patients than in NL. The hepatic expression of lipid metabolism-related genes was found to be altered in NAFLD, as previously reported. Additionally, although pro-NT levels correlated with LDL, there was no association with the main lipid metabolism-related genes. These findings suggest that pro-NT could be related to NAFLD progression.

Pro-Neurotensin/Neuromedin N and Risk of Cognitive Impairment in a Prospective Study

BACKGROUND

The neuropeptide neurotensin (NT) has been linked to cardiometabolic disease. Cardiovascular risk factors are being recognized as risk factors for cognitive impairment.

OBJECTIVE

To examine the association of the stable precursor of NT, pro-neurotensin/neuromedin N (pro-NT/NMN), with incident cognitive impairment (ICI).

METHODS

We conducted a prospective nested case-control study in the REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort. In 2003-2007, REGARDS enrolled 30,239 Black and White adults aged ≥45 years. ICI was identified using a 3-test cognitive battery administered biannually. Baseline pro-NT/NMN was measured by immunoassay in 393 cases of ICI and 490 controls after 3.4 years follow up. Multivariable logistic regression was used to calculate odds ratios (OR) of ICI by pro-NT/NMN quartiles. Race, age, and sex differences were studied with stratified models and interaction testing.

RESULTS

Pro-NT/NMN was higher in Black participants and those with hypertension and diabetes. Women with a 4th versus 1st-quartile pro-NT/NMN had 2.28-fold increased odds of ICI (95% CI 1.08-4.78) after adjusting for risk factors and incident stroke. There was no association of higher pro-NT/NMN quartiles with ICI in the overall group or men. There were no race or age differences in associations.

CONCLUSION

In this biracial population-based study, elevated systemic pro-NT/NMN was associated with more than doubled risk of ICI in women but not men. Others reported sex-specific associations in women for cardiovascular mortality and diabetes with higher pro-NT/NMN, supporting a role for future research on sex differences in the neurotensinergic system.

The Role of Central Neurotensin in Regulating Feeding and Body Weight

The small peptide neurotensin (Nts) is implicated in myriad processes including analgesia, thermoregulation, reward, arousal, blood pressure, and modulation of feeding and body weight. Alterations in Nts have recently been described in individuals with obesity or eating disorders, suggesting that disrupted Nts signaling may contribute to body weight disturbance. Curiously, Nts mediates seemingly opposing regulation of body weight via different tissues. Peripherally acting Nts promotes fat absorption and weight gain, whereas central Nts signaling suppresses feeding and weight gain. Thus, because Nts is pleiotropic, a location-based approach must be used to understand its contributions to disordered body weight and whether the Nts system might be leveraged to improve metabolic health. Here we review the role of Nts signaling in the brain to understand the sites, receptors, and mechanisms by which Nts can promote behaviors that modify body weight. New techniques permitting site-specific modulation of Nts and Nts receptor-expressing cells suggest that, even in the brain, not all Nts circuitry exerts the same function. Intriguingly, there may be dedicated brain regions and circuits via which Nts specifically suppresses feeding behavior and weight gain vs other Nts-attributed physiology. Defining the central mechanisms by which Nts signaling modifies body weight may suggest strategies to correct disrupted energy balance, as needed to address overweight, obesity, and eating disorders.

Precursor fractions of neurotensin and enkephalin might point to molecular mechanisms of cancer risk modulation during a lifestyle-intervention in germline BRCA1/2 gene mutation carriers

BACKGROUND

Germline BRCA1/2 mutation carriers (gBMC) face increased cancer risks that are modulated via non-genetic lifestyle factors whose underlying molecular mechanisms are unknown. The peptides Neurotensin (NT) and Enkephalin (ENK)-involved in tumorigenesis and obesity-related diseases-are of interest. We wanted to know whether these biomarkers differ between gBMC and women from the general population and what effect a 1-year lifestyle-intervention has in gBMC.

METHODS

The stable precursor fragments pro-NT and pro-ENK were measured at study entry (SE), after 3 and 12 months for 68 women from LIBRE-1 (a controlled lifestyle-intervention feasibility trial for gBMC involving structured endurance training and the Mediterranean Diet). The SE values were compared with a cohort of the general population including female subjects with and without previous cancer disease, non-suggestive for hereditary breast and ovarian cancer (OMA-reference). For LIBRE-1, we analysed the association between the intervention-related change in the two biomarkers and certain lifestyle factors.

RESULTS

At SE, gBMC had a higher median pro-NT than OMA-reference (in the subgroups with previous cancer 117 vs. 91 pmol/L, p = 0.002). Non-diseased gBMC had lower median pro-ENK levels when compared to the non-diseased reference group. VO2peak and pro-NT 1-year change in LIBRE-1 were inversely correlated (r = - 0.435; CI - 0.653 to - 0.151; p = 0.004). Pro-ENK correlated positively with VO2peak at SE (r = 0.323; CI 0.061-0.544; p = 0.017). Regression analyses showed an inverse association of 1-year changes for pro-NT and Omega-6/Omega-3 (Estimate: - 37.9, p = 0.097/0.080) in multivariate analysis.

CONCLUSION

Our results give first indications for lifestyle-related modification particularly of pro-NT in gBMC.

Circulating pro-neurotensin levels predict bodyweight gain and metabolic alterations in children

BACKGROUND AND AIMS

Neurotensin (NT) is an intestinal peptide released after fat ingestion, which regulates appetite and facilitates lipid absorption. Elevated plasma levels of its stable precursor pro-neurotensin (pro-NT) are associated with type 2 diabetes, obesity and cardiovascular mortality in adult populations; no data on pro-NT and metabolic disease are available in children. Aim of the study was to evaluate plasma pro-NT in relation to the presence of obesity in children, and to test if high pro-NT associates with the development of metabolic impairment later in life.

METHODS AND RESULTS

For this longitudinal retrospective study, we studied 151 overweight/obese children undergoing metabolic evaluations at University of Cagliari, Italy. Pro-NT was also assessed in 46 normal-weight, age-, sex-comparable normal-weight children, selected as a reference group. At the baseline, pro-NT was comparable between overweight/obese and normal-weight children and correlated positively with age (p < 0.001), triglycerides (p < 0.001) and inversely with HDL levels (p = 0.008). Plasma pro-NT associated with high triglycerides with OR = 5.9 (95%CI: 1.24-28.1; p = 0.026) after adjustment for multiple confounders. At the 6.5-year follow-up, high basal pro-NT associated with impaired β-cell function to compensate for insulin-resistance (disposition index: r = -0.19, p = 0.035) and predicted bodyweight increase, as indicated by percentage change of standard deviation score BMI (median(95%CI) = +20.8(+4.9-+27.5)% in the highest tertile), independently from age, sex, triglycerides and insulin-resistance (standardized β = 0.24; p = 0.036).

CONCLUSIONS

Elevated pro-NT levels in children are significantly associated with weight gain later in life and may represent a marker of susceptibility to metabolic impairment in presence of obesity.

Effect of Monoclonal Antibody Blockade of Long Fragment Neurotensin on Weight Loss, Behavior, and Metabolic Traits After High-Fat Diet Induced Obesity

BACKGROUND

Obesity is a major public health problem of our time as a risk factor for cardiometabolic disease and the available pharmacological tools needed to tackle the obesity pandemic are insufficient. Neurotensin (NTS) is a 13 amino acid peptide, which is derived from a larger precursor hormone called proneurotensin or Long Form NTS (LF NTS). NTS modulates neuro-transmitter release in the central system nervous, and facilitates intestinal fat absorption in the gastrointestinal tract. Mice lacking LF NTS are protected from high fat diet (HFD) induced obesity, hepatic steatosis and glucose intolerance. In humans, increased levels of LF NTS strongly and independently predict the development of obesity, diabetes mellitus, cardiovascular disease and mortality. With the perspective to develop therapeutic tools to neutralize LF NTS, we developed a monoclonal antibody, specifically inhibiting the function of the LF NTS (LF NTS mAb). This antibody was tested for the effects on body weight, metabolic parameters and behavior in mice made obese by high-fat diet.

METHODS

C57bl/6j mice were subjected to high-fat diet (HFD) until they reached an obesity state, then food was switched to chow. Mice were treated with either PBS (control therapy) or LF NTS mAb at the dose of 5 mg/kg once a week (i.v.). Mice weight, plasma biochemical analysis, fat and muscle size and distribution and behavioral tests were performed during the losing weight period and the stabilization period.

RESULTS

Obese mice treated with the LF NTS mAb lost weight significantly faster than the control treated group. LF NTS mAb treatment also resulted in smaller fat depots, increased fecal cholesterol excretion, reduced liver fat and larger muscle fiber size. Moreover, mice on active therapy were also less stressed, more curious and more active, providing a possible explanation to their weight loss.

CONCLUSION

Our results demonstrate that in mice subjected to HFD-induced obesity, a blockade of LF NTS with a monoclonal antibody results in reduced body weight, adipocyte volume and increased muscle fiber size, possibly explained by beneficial effects on behavior. The underlying mechanisms as well as any future role of LF NTS mAb as an anti-obesity agent warrants further studies.

Vitamin D and Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD): An Update

Non-alcoholic fatty liver disease (NAFLD) is the first cause of chronic liver disease worldwide; it ranges from simple steatosis to steatohepatitis (NASH) and, potentially, cirrhosis and hepatocarcinoma. NAFLD is also an independent risk factor for type 2 diabetes, cardiovascular diseases, and mortality. As it is largely associated with insulin resistance and related disorders, NAFLD has been recently re-named as Metabolic dysfunction-Associated Fatty Liver Disease (MAFLD). At present, there are no approved pharmacological treatments for this condition. Vitamin D is a molecule with extensive anti-fibrotic, anti-inflammatory, and insulin-sensitizing properties, which have been proven also in hepatic cells and is involved in immune-metabolic pathways within the gut–adipose tissue–liver axis. Epidemiological data support a relationship hypovitaminosis D and the presence of NAFLD and steatohepatitis (NASH); however, results from vitamin D supplementation trials on liver outcomes are controversial. This narrative review provides an overview of the latest evidence on pathophysiological pathways connecting vitamin D to NAFLD, with emphasis on the effects of vitamin D treatment in MAFLD by a nonsystematic literature review of PubMed published clinical trials. This article conforms to the Scale for Assessment of Narrative Review Articles (SANRA) guidelines. Evidence so far available supports the hypothesis of potential benefits of vitamin D supplementation in selected populations of NAFLD patients, as those with shorter disease duration and mild to moderate liver damage.

Magnitude of rise in proneurotensin is related to amount of triglyceride appearance in blood after standardized oral intake of both saturated and unsaturated fat

Background

In rodents, neurotensin contributes to high fat diet induced obesity by facilitation of intestinal fat absorption. The effect of oral lipid load on plasma proneurotensin and relationship with plasma triglycerides in humans is unknown.

Aim

To investigate the acute effects of an oral lipid load on proneurotensin and plasma triglycerides and their interrelationships in healthy individuals.

Setting/ methods

Twenty-two healthy subjects were given 150 mL of full milk cream (54 g fat) and 59 mL of pure olive oil (54 g fat) in the fasted state at two different occasions separated by at least 1 week in random order. Venous blood was drawn at fasted before 0 h (h) and at 1 h, 2 h and 4 h after ingestion. Post-ingested values of proneurotensin and plasma triglycerides were compared with fasting levels and post ingestion Area Under the Curve (AUC) of proneurotensin was correlated with that of plasma triglycerides.

Results

An immediate rise of plasma proneurotensin and plasma triglycerides were observed after ingestion of cream with maximum increase at 2 h for proneurotensin [mean (95% confidence interval)] of 22 (12–31) pmol/L (P < 0.001) and at 3 h for triglycerides of 0.60 (0.43–0.78) mmol/L (P < 0.001). Similarly, plasma proneurotensin and plasma triglycerides increased after ingestion of olive oil with maximum increase of proneurotensin at 3 h of 62 (46–78) pmol/L (P < 0.001) and plasma triglycerides at 3 h of 0.32 (0.18–0.45) mmol/L (P < 0.001). The post lipid load AUC for proneurotensin correlated significantly with the AUC for plasma triglycerides both after cream (r = 0.49, P = 0.021) and olive oil (r = 0.55, P = 0.008), respectively.

Conclusion

Proneurotensin increases after an oral lipid load of both cream and olive oil and the rise of post-ingestion plasma triglycerides is significantly related to the rise of post-ingestion proneurotensin.

Chronic high-fat diet consumption induces an alteration in plasma/brain neurotensin signaling, metabolic disturbance, systemic inflammation/oxidative stress, brain apoptosis, and dendritic spine loss

Chronic high-fat diet (HFD) consumption caused not only negative effects on obesity and metabolic disturbance, but also instigated several brain pathologies, including dendritic spine loss. In addition, alterations in plasma/brain neurotensin (NT) levels and NT signaling were observed in obesity. However, the mechanistic link between the NT levels in plasma and brain, NT signaling, and peripheral/brain pathologies following prolonged HFD consumption still needs to be elucidated. We hypothesized that an increase in peripheral/brain NT signaling were associated with peripheral/brain pathologies after prolonged HFD consumption. Male Wistar rats (n = 24) were given either a normal diet (ND) or a HFD for 12 and 40 weeks. At the end of each time course, metabolic parameters and plasma NT levels were measured. Rats were then decapitated and the brains were examined the levels of brain NT, hippocampal reactive oxygen species, the number of Iba-1 positive cells, the dendritic spine densities, and the expression of NT-, mitophagy-, autophagy-, and apoptotic-related proteins. The findings showed an increase in the level of plasma NT with dyslipidemia, metabolic disturbances, systemic inflammation/oxidative stress, and hippocampal pathologies in rats fed HFD for 12 and 40 weeks. The expression of brain NT signaling and brain apoptosis were markedly increased after 40 weeks of HFD feeding. These results indicated that the alteration in the level of circulating/brain NT and its downstream signaling were associated with central and peripheral pathologies after long-term HFD intake. Therefore, these alterations in NT level or its signaling could be considered as a therapeutic target in treating obesity.

Neurotensin up-regulation is associated with advanced fibrosis and hepatocellular carcinoma in patients with MAFLD

BACKGROUND & AIMS

Neurotensin (NTS), a 13-aminoacid peptide localized in central nervous system and gastrointestinal tract, is involved in lipid metabolism and promotes various cancers onset mainly by binding to neurotensin receptor 1 (NTSR1). Increased plasma levels of pro-NTS, the stable NTS precursor, have been associated with type 2 diabetes (T2D), cardiovascular diseases and metabolic associated fatty liver disease (MAFLD). We aimed to evaluate 1) the impact of NTS rs1800832 and NTSR1 rs6090453 genetic variants on liver damage in 1166 MAFLD European individuals, 2) the relation between NTS variant and circulating pro-NTS and 3) the hepatic NTS expression by RNAseq transcriptomic analysis in 125 bariatric patients.

RESULTS

The NTS rs1800832 G allele was associated with hepatic fibrosis (OR 1.27, 95% confidence interval (CI). 1.02-1.58; p = 0.03), even more in carriers of both NTS and NTSR1 G risk alleles (OR 1.17, 95% CI. 1.03-1.34; p = 0.01), with cirrhosis (OR 1.58, 95% CI. 1.07-2.34; p = 0.02) and HCC (OR 1.98, 95% CI. 1.24-3.2; p = 0.004). Pro-NTS circulating levels were correlated with T2D (p = 0.005), BMI, (p = 0.04), age (p = 0.0016), lobular inflammation (p = 0.0025), fibrosis>2 (p < 0.0001), cirrhosis (p = 0.0009) and HCC (p < 0.0001) and more so after stratification for the NTS G allele. Transcriptomic data showed that hepatic NTS expression correlated with that of fibrogenic genes (p < 0.05).

CONCLUSIONS

NTS rs1800832 variant is associated with advanced fibrosis and HCC in MAFLD patients likely affecting NTS protein activity. The rs6090453 NTSR1 gene variant synergizes with NTS rs1800832 mutation to promote liver damage. Prospective studies are necessary to confirm NTS role in liver disease progression.

Epidemiology and pathophysiology of the association between NAFLD and metabolically healthy or metabolically unhealthy obesity

The prevalence of nonalcoholic fatty liver disease (NAFLD) is continuing to rise in many countries, paralleling the epidemic of obesity worldwide. In the last years, the concept of metabolically healthy obesity [MHO, generally defined as obesity without metabolic syndrome (MetS)] has raised considerable scientific interest. MHO is a complex phenotype with risks intermediate between metabolically healthy individuals with normal-weight (NWMH) and patients who are obese and metabolically unhealthy (MUO, i.e. obesity with MetS). In this review we aimed to examine the association and pathophysiological link of NAFLD with MHO and MUO. Compared to NWMH individuals, patients with obesity, regardless of the presence of MetS features, are at higher risk of all-cause mortality and cardiovascular events. Moreover, MHO patients have a greater risk of NAFLD development and progression compared to NWMH individuals. However, this risk is generally lower than that of MUO patients, suggesting a stronger adverse effect of coexisting MetS disorders than obesity per se on the severity of NAFLD. Nevertheless, since MHO is a dynamic state (with a significant proportion of MHO subjects progressing to MUO over time) and NAFLD itself may predict the transition from MHO to MUO, we believe that any effort should be made to identify NAFLD in all obese individuals, although they appear to be "metabolically healthy". Future research is needed to better understand the role of NAFLD and other pathogenic factors potentially involved in the transition from MHO to MUO and to elucidate how this transition may affect the presence and severity of NAFLD.

Absence of neurotensin attenuates intestinal dysbiosis and inflammation by maintaining Mmp7/α-defensin axis in diet-induced obese mice

We previously reported that high levels of plasma neurotensin (NT), a gut hormone released from enteroendocrine cells of the small bowel, contribute to obesity and comorbid conditions. Gut microbiota has been implicated in the obesity development. Paneth cells are critical in maintaining gut microbiota composition and homeostasis by releasing antimicrobial proteins including α-defensins. The purpose of our current study was to determine the possible role of NT in gut microbiota composition and α-defensin gene expression associated with obesity. Here we show that the ratio of Firmicutes/Bacteroidetes (F/B ratio) and intestinal proinflammatory cytokines is significantly increased in NT+/+ mice fed with a high-fat diet (HFD) which were improved in NT-deficient mice. HFD disrupted the intestinal Mmp7/α-defensin axis, which was completely prevented in NT-/- mice. In addition, NT treatment inhibited DEFA5 expression and concurrent NF-κB activity, which was blocked by a pan PKC inhibitor (Gö6983) or an inhibitor for atypical PKCs (CRT0066854). More importantly, the shRNA-mediated knockdown of atypical PKCτ reversed NT-attenuated DEFA5 expression and increased NF-κB activity. NT contributes to the HFD-induced disruption of gut microbiota composition and α-defensin expression. PKCτ/λ plays a central role in NT-mediated α-defensin gene expression which might be mediated through the inhibition of NF-κB signaling pathways in Paneth cells.

Identification of U-shaped curve relation between proneurotensin and risk of coronary artery disease (CAD) in patients with premature CAD

BACKGROUND AND AIMS

Neurotensin (NT) is a gut hormone with broad effects on the cardiovascular system. Recent data suggested that circulating proneurotensin (pro-NT)-the stable precursor fragment of NT-could independently predict cardiovascular artery disease (CAD) development. However, serum pro-NT levels in patients with premature cardiovascular artery disease (PCAD) are still unknown. This study aims to determine serum pro-NT levels in patients with PCAD and investigate its relationship with PCAD risk.

METHODS AND RESULTS

A total of 490 subjects, including 364 with PCAD and 126 without PCAD (NPCAD), and 182 controls were enrolled in the study. Data of baseline clinical parameters and biochemical variables were collected. Serum pro-NT levels were measured by ELISA. Serum pro-NT levels were higher in patients with PCAD than in controls (59.42 ± 66.66 vs. 38.07 ± 48.48 pg/mL, P < 0.05), especially in patients with BMI<25 kg/m². Serum pro-NT levels were independently related to PCAD (β = 0.349, P < 0.001), and the association revealed a U-shaped curve characteristic between pro-NT tertiles and CAD risk in patients with premature CAD and controls. Subjects with low and high tertiles of pro-NT levels had 1.79-fold and 2.23-fold higher risks of PCAD, respectively, than subjects with median pro-NT levels (P < 0.05). After adjusting for age, gender, and BMI in Model 1 and other confounders in Model 2 and Model 3, the U-shaped relationship remained significant.

CONCLUSION

Serum pro-NT levels were significantly increased in patients with PCAD. The association between pro-NT levels and PCAD risk presents a U-shaped curve characteristic, which demonstrated that subjects with lower and higher pro-NT levels both were more likely to have PCAD.

The association between plasma proneurotensin and glucose regulation is modified by country of birth

The prevalence of type 2 diabetes (T2D) has increased dramatically in Middle Eastern populations that represent the largest non-European immigrant group in Sweden today. As proneurotensin predicts T2D, the aim of this study was to investigate differences in proneurotensin levels across populations of Middle Eastern and Caucasian origin and to study its associations with indices of glucose regulation. Participants in the age 30 to 75 years, living in Malmö, Sweden, and born in Iraq or Sweden, were recruited from the census register. Anthropometrics and fasting samples were collected and oral glucose tolerance tests conducted assessing insulin secretion (DIo) as well as insulin sensitivity (ISI). A total of 2155 individuals participated in the study, 1398 were Iraqi-born and 757 were Swedish-born participants. Higher fasting proneurotensin levels were observed in Iraqi- compared to Swedish-born participants (137.5 vs. 119.8 pmol/L; p < 0.001) data adjusted for age, sex and body mass index. In Iraqi participants only, plasma proneurotensin was associated with impaired glucose regulation assessed as ISI, DIo and HbA1c, and significant interactions between country of birth and proneurotensin were observed (Pinteraction ISI = 0.048; Pinteraction DIo = 0.014; PinteractionHbA1c = 0.029). We report higher levels of proneurotensin in the general Middle Eastern population. The finding that Middle Eastern origin modifies the relationship of proneurotensin with indices of glucose regulation suggests that proneurotensin may be a stronger determinant of T2D in Middle Eastern as compared to Caucasian populations. These findings may explain part of the excess T2D risk in the Middle Eastern population but needs to be explored further.

Role of the intestinal microbiome in liver fibrosis development and new treatment strategies

Liver cirrhosis is a major cause of morbidity and mortality worldwide. The most common chronic liver diseases in western countries are alcohol-associated liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Although these diseases have different causes, liver fibrosis develops via shared mechanisms. The liver and intestinal microbiome are linked by the portal vein and have bidirectional interactions. Changes in the intestinal microbiome contribute to the pathogenesis and progression of liver diseases including ALD, NAFLD, viral hepatitis and cholestatic disorders, based on studies in patients and animal models. Intestinal microbial dysbiosis has been associated with liver cirrhosis and its complications. We review the mechanisms by which alterations in the microbiome contribute to liver fibrosis and discuss microbiome-based treatment approaches.

Long-Acting Neurotensin Synergizes With Liraglutide to Reverse Obesity Through a Melanocortin-Dependent Pathway

Neurotensin (NT), a gut hormone and neuropeptide, increases in circulation after bariatric surgery in rodents and humans and inhibits food intake in mice. However, its potential to treat obesity and the subsequent metabolic dysfunctions have been difficult to assess owing to its short half-life in vivo. Here, we demonstrate that a long-acting, pegylated analog of the NT peptide (P-NT) reduces food intake, body weight, and adiposity in diet-induced obese mice when administered once daily for 6 days. Strikingly, when P-NT was combined with the glucagon-like peptide 1 mimetic liraglutide, the two peptides synergized to reduce food intake and body weight relative to each monotherapy, without inducing a taste aversion. Further, P-NT and liraglutide coadministration improved glycemia and reduced steatohepatitis. Finally, we show that the melanocortin pathway is central for P-NT-induced anorexia and necessary for the full synergistic effect of P-NT and liraglutide combination therapy. Overall, our data suggest that P-NT and liraglutide combination therapy could be an enhanced treatment for obesity with improved tolerability compared with liraglutide monotherapy.

Lp-PLA2 activity and mass and CRP are associated with incident symptomatic peripheral arterial disease

Long follow up is needed in prospective cohort study evaluation of plasma biomarkers for incident peripheral arterial disease (PAD) Middle-aged PAD-free individuals from the cardiovascular cohort of the Malmö Diet and Cancer study (n = 5550; 1991-94) were followed prospectively for a median time of 23.4 years. The plasma biomarkers lipoprotein-associated phospholipase A2 (Lp-PLA₂) activity and mass, proneurotensin, and CRP, were studied in relation to incidence of PAD until December 31^st, 2016. The diagnosis of PAD could be validated and confirmed in 98%. Cox regression was used to calculate hazard ratios (HR) per 1 standard deviation increment of each respective log transformed plasma biomarker. Cumulative incidence of PAD was 4.4% (men 5.9%, women 3.3%). Adjusting for age, gender, smoking, body mass index, hypertension, diabetes mellitus, Lp-PLA₂ activity (HR 1.33; 95% CI 1.17-1.52), Lp-PLA₂ mass (HR 1.20; 95% CI 1.05-1.37) and CRP (HR 1.55; 95% CI 1.36-1.76) remained independently associated with incident PAD. The plasma biomarkers Lp-PLA₂ activity and mass, and CRP were markers of PAD risk, implying that they might be useful biomarkers for subclinical atherosclerosis and atherosclerotic disease.

Kinase suppressor of Ras 1 and Exo70 promote fatty acid-stimulated neurotensin secretion through ERK1/2 signaling

Neurotensin is a peptide hormone released from enteroendocrine cells in the small intestine in response to fat ingestion. Although the mechanisms regulating neurotensin secretion are still incompletely understood, our recent findings implicate a role for extracellular signal-regulated kinase 1 and 2 as positive regulators of free fatty acid-stimulated neurotensin secretion. Previous studies have shown that kinase suppressor of Ras 1 acts as a molecular scaffold of the Raf/MEK/extracellular signal-regulated kinase 1 and 2 kinase cascade and regulates intensity and duration of extracellular signal-regulated kinase 1 and 2 signaling. Here, we demonstrate that inhibition of kinase suppressor of Ras 1 attenuates neurotensin secretion and extracellular signal-regulated kinase 1 and 2 signaling in human endocrine cells. Conversely, we show that overexpression of kinase suppressor of Ras 1 enhances neurotensin secretion and extracellular signal-regulated kinase 1 and 2 signaling. We also show that inhibition of extracellular signal-regulated kinase 2 and exocyst complex component 70, a substrate of extracellular signal-regulated kinase 2 and mediator of secretory vesicle exocytosis, potently inhibits basal and docosahexaenoic acid-stimulated neurotensin secretion, whereas overexpression of exocyst complex component 70 enhances basal and docosahexaenoic acid-stimulated neurotensin secretion. Together, our findings demonstrate a role for kinase suppressor of Ras 1 as a positive regulator of neurotensin secretion from human endocrine cells and indicate that this effect is mediated by the extracellular signal-regulated kinase 1 and 2 signaling pathway. Moreover, we reveal a novel role for exocyst complex component 70 in regulation of neurotensin vesicle exocytosis through its interaction with the extracellular signal-regulated kinase 1 and 2 signaling pathway.

Circulating Pro-Neurotensin in gestational diabetes mellitus

BACKGROUND AND AIMS

Pro-Neurotensin (NT), a stable surrogate parameter of NT, has recently been introduced as a peptide predicting the development of obesity, diabetes mellitus, cardiovascular diseases, and cardiovascular mortality. However, regulation of Pro-NT in gestational diabetes mellitus (GDM) remains uninvestigated.

METHODS AND RESULTS

Pro-NT was quantified in 74 women with GDM, 74 healthy, gestational age-matched, pregnant controls, as well as in a second cohort comprising of 74 healthy, non-pregnant control women, using a chemiluminometric sandwich immunoassay. Pro-NT was correlated to measures of obesity, hypertension, glucose and lipid metabolism, renal function, and inflammation. Mean ± standard deviation of circulating Pro-NT levels were not significantly different in women with GDM (100.2 ± 75.7 pmol/l) as compared to healthy, pregnant controls (103.2 ± 37.4 pmol/l) and healthy, non-pregnant female controls (105.9 ± 38.9 pmol/l) (p = 0.661). Homeostasis model assessment of insulin resistance (HOMA-IR) and creatinine positively correlated with serum Pro-NT in multivariate regression analysis. In contrast, free fatty acids (FFA) were inversely correlated with circulating Pro-NT. Results sustained adjustment for pregnancy status.

CONCLUSIONS

Circulating Pro-NT is not independently associated with GDM, but is with HOMA-IR, creatinine, and FFA even after adjustment for pregnancy status.

Roles of Gut-Derived Secretory Factors in the Pathogenesis of Non-Alcoholic Fatty Liver Disease and Their Possible Clinical Applications

The rising prevalence of non-alcoholic fatty liver disease (NAFLD) parallels the global increase in the number of people diagnosed with obesity and metabolic syndrome. The gut-liver axis (GLA) plays an important role in the pathogenesis of NAFLD/non-alcoholic steatohepatitis (NASH). In this review, we discuss the clinical significance and underlying mechanisms of action of gut-derived secretory factors in NAFLD/NASH, focusing on recent human studies. Several studies have identified potential causal associations between gut-derived secretory factors and NAFLD/NASH, as well as the underlying mechanisms. The effects of gut-derived hormone-associated drugs, such as glucagon-like peptide-1 analog and recombinant variant of fibroblast growth factor 19, and other new treatment strategies for NAFLD/NASH have also been reported. A growing body of evidence highlights the role of GLA in the pathogenesis of NAFLD/NASH. Larger and longitudinal studies as well as translational research are expected to provide additional insights into the role of gut-derived secretory factors in the pathogenesis of NAFLD/NASH, possibly providing novel markers and therapeutic targets in patients with NAFLD/NASH.

Neurotensin Is a Lipid-Induced Gastrointestinal Peptide Associated with Visceral Adipose Tissue Inflammation in Obesity

Neurotensin (NT) is a 13-amino acid peptide localized in the neuroendocrine cells of the small intestine, which promotes fat absorption and fatty acids translocation in response to lipid ingestion. NT-knock-out mice fed with a high-fat diet are protected from obesity, fatty liver, and the development of insulin-resistance. In humans, higher plasma levels of pro-NT, which is the stable circulating precursor of NT, predict obesity, type 2 diabetes (T2D), and cardiovascular disease. In obesity, the presence of visceral adipose tissue (VAT) inflammation leads to unfavorable metabolic outcomes and is associated with the development of T2D and non-alcoholic fatty liver disease (NAFLD). In this study, we investigated the relationship between plasma pro-NT levels and the presence of VAT inflammation in biopsies from 40 morbidly obese subjects undergoing bariatric surgery. We demonstrated that higher proNT levels are significantly associated with greater macrophages infiltration, HIF-1α, WISP-1, and UNC5B expression in VAT (all p < 0.01) due to the diagnosis of T2D and NAFLD. The overall results show that, in obesity, pro-NT is a biomarker of VAT inflammation and insulin-resistance. Additionally, NT may be involved in the development of dysmetabolic conditions likely mediated by increased gut fat absorption and the presence of a proinflammatory milieu in the adipose tissue.