Longitudinal Changes in Serum Levels of Angiopoietin-Like Protein 6 and Selenoprotein P After Gastric Bypass Surgery

Angiopoietin-Like Proteins: Cardiovascular Biology and Therapeutic Targeting for the Prevention of Cardiovascular Diseases

Despite the best pharmacologic tools available, cardiovascular diseases (CVDs) remain a major cause of morbidity and mortality in developed countries. After 2 decades of research, new therapeutic targets, such as angiopoietin-like proteins (ANGPTLs), are emerging. ANGPTLs belong to a family of 8 members, from ANGPTL1 to ANGPTL8; they have structural homology with angiopoietins and are secreted in the circulation. ANGPTLs display a multitude of physiological and pathologic functions; they contribute to inflammation, angiogenesis, cell death, senescence, hematopoiesis, and play a role in repair, maintenance, and tissue homeostasis. ANGPTLs-particularly the triad ANGPTL3, 4, and 8-have an established role in lipid metabolism through the regulation of triacylglycerol trafficking according to the nutritional status. Some ANGPTLs also contribute to glucose metabolism. Therefore, dysregulation in ANGPTL expression associated with abnormal circulating levels are linked to a plethora of CVD and metabolic disorders including atherosclerosis, heart diseases, diabetes, but also obesity and cancers. Because ANGPTLs bind to different receptors according to the cell type, antagonists are therapeutically inadequate. Recently, direct inhibitors of ANGPTLs, mainly ANGPTL3, have been developed, and specific monoclonal antibodies and antisense oligonucleotides are currently being tested in clinical trials. The aim of the current review is to provide an up-to-date preclinical and clinical overview on the function of the 8 members of the ANGPTL family in the cardiovascular system, their contribution to CVD, and the therapeutic potential of manipulating some of them.

Clinical improvement may not reflect metabolic homeostasis normalization in subjects with and without Roux-En-Y bariatric surgery after 12 years: comparison of surgical subjects to a lean cohort

Background

A 12-year study comparing clinical outcomes following Roux-en-Y bariatric surgery showed long-term weight loss with remission/prevention of type-2-diabetes (T2D), hypertension and dyslipidemia. However, it is unknown whether the underlying homeostatic metabolic processes involving hepatokines, adipokines and myokines also normalize. Using this 12-year study, we determined whether metabolic indices improved in post-surgical (BMI:34.4kg/m2) versus non-surgical comparator-subjects-with-obesity (BMI:43.8kg/m2) at 12-year follow-up (both cohorts with baseline diabetes), and if post-surgical subjects normalized their metabolic processes to those of a normal-weight cohort without diabetes.

Methods

Cross-sectional design. Plasma from a cohort of Roux-en-Y bariatric surgery (n=50) and non-surgery (n=76) comparator-subjects-with-obesity (both cohorts at 12-year follow-up) plus a normal-weight cohort (n=39) was assayed by Luminex immunoassay or ELISA for hepatokines [angiopoietin-like proteins-(ANGPTL3; ANGPTL4; ANGPTL6); fibroblast growth factors-(FGF19; FGF21; FGF23)]; adipokines [adipsin; adiponectin; FGF19] and myonectin.

Results

After age and gender adjustment, surgery versus comparator-subjects-with-obesity had lower BMI (34.4 ± 1.0 vs 43.8 ± 0.9kg/m2; p<0.0001), HbA1c (6.2 ± 0.3 vs 7.7 ± 0.2%; p<0.0001), insulin resistance (HOMA-IR, 2.0 ± 1.5 vs 10.8 ± 1.4; p<0.0001) fat mass (45.6 ± 2.2 vs 60.0 ± 2.0; p<0.0001), HDL-C (55.4 ± 2.6 vs 42.6 ± 2.3mg/dL; p<0.0001), triglycerides (130 ± 14 vs 187 ± 12mg/dL; p<0.0001) and higher adiponectin (25.9 ± 2.3 vs 15.7 ± 2.0µg/ml; p<0.001); Adipsin, ANGPTL3, ANGPTL4, ANGPTL6, FGF19, FGF21, FGF23 and myonectin did not differ. Surgery versus normal-weight group: higher ANGPTL4 (156 ± 6 vs 119 ± 7ng/mL; p<0.0001), higher FGF23 (96.4 ± 10.1 vs 50.9 ± 11.5pg/mL; p=0.007) and lower myonectin (744 ± 55 vs 969 ± 66ng/mL; p=0.002); adiponectin, adipsin ANGPTL3, ANGPTL6, FGF19, FGF21 did not differ. Non-surgery comparator-subjects-with-obesity versus normal-weight group: higher adipsin (1859 ± 94 vs 1314 ± 133ng/mL; p=0.0001), higher FGF23 (84.6 ± 8.5 vs 50.9 ± 11.5pg/mL; p<0.0001) and higher ANGPTL4 (171 ± 5 vs 119 ± 7ng/mL; p<0.0001); adiponectin ANGPTL3, ANGPTL6, FGF19, FGF21 and myonectin did not differ.

Conclusion

Bariatric surgery markedly improved anthropometric and metabolic features versus comparator-subjects-with-obesity at 12-year follow-up, indicating benefit of weight loss. However, despite weight loss, these patients still had class-1 obesity, as reflected in the adipokine, hepatokine and myokine markers of body homeostasis that did not completely normalize to indicative values of normal-weight subjects, suggesting either that this is the new normal for these patients or that weight loss to a BMI<25kg/m2 is needed for normalization of these parameters.

Effect of alternate day fasting combined with aerobic exercise on non-alcoholic fatty liver disease: A randomized controlled trial

Innovative non-pharmacological lifestyle strategies to treat non-alcoholic fatty liver disease (NAFLD) are critically needed. This study compared the effects of alternate day fasting (ADF) combined with exercise to fasting alone, or exercise alone, on intrahepatic triglyceride (IHTG) content. Adults with obesity and NAFLD (n = 80, 81% female, age: 23-65 years) were randomized to 1 of 4 groups for 3 months: combination of ADF (600 kcal/2,500 kJ "fast day" alternated with an ad libitum intake "feast day") and moderate-intensity aerobic exercise (5 session per week, 60 min/session); ADF alone; exercise alone; or a no-intervention control group. By month 3, IHTG content was significantly reduced in the combination group (-5.48%; 95% CI, -7.77% to -3.18%), compared with the exercise group (-1.30%; 95% CI, -3.80% to 1.20%; p = 0.02) and the control group (-0.17%; 95% CI, -2.17% to 1.83%; p < 0.01) but was not significantly different versus the ADF group (-2.25%; 95% CI, -4.46% to -0.04%; p = 0.05). Body weight, fat mass, waist circumference, and alanine transaminase (ALT) levels significantly decreased, while insulin sensitivity significantly increased in the combination group compared with the control group. Lean mass, aspartate transaminase (AST), HbA1c, blood pressure, plasma lipids, liver fibrosis score, and hepatokines (fetuin-A, FGF-21, and selenoprotein P) did not differ between groups. Combining intermittent fasting with exercise is effective for reducing hepatic steatosis in patients with NAFLD but may offer no additional benefit versus fasting alone.

Serum Fibrinogen-Like Protein 1 Levels in Obese Patients Before and After Laparoscopic Sleeve Gastrectomy: A Six-Month Longitudinal Study

PURPOSE

Fibrinogen-like protein (FGL)-1 is an original hepatokine with a critical role in developing hepatic steatosis. This study intends to examine the pre- and postoperative serum FGL-1 levels in bariatric patients and identify its relationship with other clinical indicators.

PATIENTS AND METHODS

Ninety-two individuals (60 bariatric patients and 32 people with normal weight) were enrolled in this research between July 2018 and April 2021. All bariatric patients finished follow-up visits 6 months after laparoscopic sleeve gastrectomy (LSG). Clinical data, anthropometric parameters, biochemical variables, FibroScan, and serum FGL-1 levels were collected at baseline and 6 months after LSG.

RESULTS

FGL-1 levels in patients with obesity (44.66±20.03 ng/mL) were higher than in individuals with normal weight (20.73±9.73 ng/mL, p < 0.001). After LSG, FGL-1 levels were significantly decreased (27.53±11.45 ng/mL, p < 0.001). Besides, body mass index (BMI), liver enzyme levels, glucose metabolism, lipid metabolism, uric acid (UA), controlled attenuation parameter (CAP), and liver stiffness measurement (LSM) were significantly improved. After adjusting possible confounders, FGL-1 levels at baseline were negatively associated with changes in LSM levels; changes in FGL-1 levels showed positive correlations with changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST) and UA levels at 6 months after surgery.

CONCLUSION

Serum FGL-1 levels were significantly decreased following LSG in patients with obesity. The preoperative serum FGL-1 levels could be a predictor of postoperative liver fibrosis improvement. Furthermore, the decreased FGL-1 levels were associated with improved liver enzymes and UA but not with bodyweight or glucolipid metabolism.

Effects of Bariatric Surgeries on Fetuin-A, Selenoprotein P, Angiopoietin-Like Protein 6, and Fibroblast Growth Factor 21 Concentration

Obesity is a civilization disease representing a global health problem. Excessive body weight significantly reduces the quality of life. It is also associated with the leading causes of death, including type 2 diabetes mellitus, cardiovascular diseases, and numerous types of cancer. The mainstay of therapy is a dietary treatment. However, in morbidly obese patients, dietary treatment is often insufficient. In these patients, the most effective procedure is bariatric surgery, but it is still difficult to predict its outcome and metabolic changes. Hepatokines are proteins secreted by hepatocytes. Many of them, including fetuin-A, selenoprotein P, angiopoietin-like protein 6, and fibroblast growth factor 21, have been linked to metabolic dysfunctions. In this context, hepatokines may prove helpful. This review investigates the possible changes in hepatokine profiles after selected bariatric surgery protocols. In this regard, Roux-en-Y gastric bypass is the most studied type of surgery. The overall analysis of published research identified fetuin-A as a potential marker of metabolic alternations in patients after bariatric surgery.

Metabolic adaptations after bariatric surgery: adipokines, myokines and hepatokines

This review addresses the impact of bariatric surgery on the endocrine aspects of white adipose tissue, muscle and the liver. We describe literature supporting the notion that adipokines, myokines and hepatokines likely act in concert and drive many of the long-term metabolic improvements following surgery. Circulating adiponectin is increased while secretion of pro-inflammatory interleukins (1, 6 and 8) decreases, alongside leptin secretion. The metabolic improvements observed in the muscle might relate to reduction of myokines contributing to insulin resistance (including myostatin, brain-derived neurotrophic factor and fibroblast growth factor-21). Subject to exception, hepatokine secretion is generally increased (such as insulin-like growth factor-binding protein 2, adropin and sex hormone-binding globulin). In conclusion, bariatric surgery restores metabolic functions by enhancing the time-dependent secretion of anti-inflammatory, insulin-sensitizing and antilipemic factors. Further research is needed to understand the molecular mechanisms by which these factors may trigger the remission of obesity-related comorbidities following bariatric surgery.

Selenium and Selenoproteins in Adipose Tissue Physiology and Obesity

Selenium (Se) homeostasis is tightly related to carbohydrate and lipid metabolism, but its possible roles in obesity development and in adipocyte metabolism are unclear. The objective of the present study is to review the current data on Se status in obesity and to discuss the interference between Se and selenoprotein metabolism in adipocyte physiology and obesity pathogenesis. The overview and meta-analysis of the studies on blood Se and selenoprotein P (SELENOP) levels, as well as glutathione peroxidase (GPX) activity in obese subjects, have yielded heterogenous and even conflicting results. Laboratory studies demonstrate that Se may modulate preadipocyte proliferation and adipogenic differentiation, and also interfere with insulin signaling, and regulate lipolysis. Knockout models have demonstrated that the selenoprotein machinery, including endoplasmic reticulum-resident selenoproteins together with GPXs and thioredoxin reductases (TXNRDs), are tightly related to adipocyte development and functioning. In conclusion, Se and selenoproteins appear to play an essential role in adipose tissue physiology, although human data are inconsistent. Taken together, these findings do not support the utility of Se supplementation to prevent or alleviate obesity in humans. Further human and laboratory studies are required to elucidate associations between Se metabolism and obesity.

Changes in Liver Gene Expression and Plasma Concentration of Rbp4, Fetuin-A, and Fgf21 in Sprague-Dawley Rats Subjected to Different Dietary Interventions and Bariatric Surgery

Purpose

To study the effect of duodenal-jejunal omega switch (DJOS) in combination with different dietary patterns on the retinol-binding protein (RBP4), fetuin-A, and fibroblast growth factor 21 (FGF21) plasma levels and their hepatic gene expressions in rats.

Methods

A high-fat diet (HF) was given to 28 rats and 28 more were fed with a control diet (CD) for 2 months. After that, half of each group underwent either DJOS or SHAM surgery. For the next 2 months, half of the animals in each operation group were kept on the same diet as before and half of them had the diet changed. After 16 weeks of the experiment RBP4, fetuin-A, and FGF21 plasma levels as well as liver Rbp4, Ahsg, and Fgf21 gene expressions were measured.

Results

DJOS had a reductive impact on plasma levels of RBP4, fetuin-A, and FGF21 and Rbp4, Ahsg, and Fgf21 relative gene expression in the liver when compared to SHAM. The HF/HF group expressed significantly higher RBP4 and fetuin-A plasma levels in comparison to the control. The HF diet used before and/or after surgery led to upregulation of Rbp4, Ahsg, and Fgf21 relative gene expression. The lowest levels of analyzed parameters were observed in the CD/CD group.

Conclusions

The efficiency of DJOS surgery, measured by hepatokines' plasma levels and their gene expressions in the liver, depends on the type of diet applied before and after surgery. Manipulation of dietary patterns can lead to marked improvements in metabolic profile after DJOS surgery.