Metabolic adaptations after bariatric surgery: adipokines, myokines and hepatokines

Myokines as potential mediators of changes in glucose homeostasis and muscle mass after bariatric surgery

Myokines are bioactive peptides released by skeletal muscle. Myokines exert auto-, para-, or endocrine effects, enabling them to regulate many aspects of metabolism in various tissues. However, the contribution of myokines to the dramatic changes in glucose homeostasis and muscle mass induced by bariatric surgery has not been established. Our review highlights that myokines such as brain-derived neurotrophic factor (BDNF), meteorin-like protein (Metrnl), secreted protein acidic and rich in cysteine (SPARC), apelin (APLN) and myostatin (MSTN) may mediate changes in glucose homeostasis and muscle mass after bariatric surgery. Our review also identifies myonectin as an interesting candidate for future studies, as this myokine may regulate lipid metabolism and muscle mass after bariatric surgery. These myokines may provide novel therapeutic targets and biomarkers for obesity, type 2 diabetes and sarcopenia.

Role of the Unique Secreted Peptide Adropin in Various Physiological and Disease States

Adropin, a secreted peptide hormone identified in 2008, plays a significant role in regulating energy homeostasis, glucose metabolism, and lipid metabolism. Its expression is linked to dietary macronutrient intake and is influenced by metabolic syndrome, obesity, diabetes, and cardiovascular diseases. Emerging evidence suggests that adropin might be a biomarker for various conditions, including metabolic syndrome, coronary artery disease, and hypertensive disorders complicating pregnancy. In cerebrovascular diseases, adropin demonstrates protective effects by reducing blood-brain barrier permeability, brain edema, and infarct size while improving cognitive and sensorimotor functions in ischemic stroke models. The protective effects of adropin extend to preventing endothelial damage, promoting angiogenesis, and mitigating inflammation, making it a promising therapeutic target for cardiovascular and neurodegenerative diseases. This review provides a comprehensive overview of adropin's multifaceted roles in physiological and pathological conditions, as well as our recent work demonstrating adropin's role in subarachnoid hemorrhage-mediated neural injury and delayed cerebral infarction.

Adipokines in the Crosstalk between Adipose Tissues and Other Organs: Implications in Cardiometabolic Diseases

Adipose tissue was previously regarded as a dormant organ for lipid storage until the identification of adiponectin and leptin in the early 1990s. This revelation unveiled the dynamic endocrine function of adipose tissue, which has expanded further. Adipose tissue has emerged in recent decades as a multifunctional organ that plays a significant role in energy metabolism and homeostasis. Currently, it is evident that adipose tissue primarily performs its function by secreting a diverse array of signaling molecules known as adipokines. Apart from their pivotal function in energy expenditure and metabolism regulation, these adipokines exert significant influence over a multitude of biological processes, including but not limited to inflammation, thermoregulation, immune response, vascular function, and insulin sensitivity. Adipokines are pivotal in regulating numerous biological processes within adipose tissue and facilitating communication between adipose tissue and various organs, including the brain, gut, pancreas, endothelial cells, liver, muscle, and more. Dysregulated adipokines have been implicated in several metabolic diseases, like obesity and diabetes, as well as cardiovascular diseases. In this article, we attempted to describe the significance of adipokines in developing metabolic and cardiovascular diseases and highlight their role in the crosstalk between adipose tissues and other tissues and organs.

Effects of bariatric surgery on muscle strength and quality: A systematic review and meta-analysis

Obesity is a major health burden worldwide. Although bariatric surgery (BS) is recognized as an effective strategy for weight loss and comorbidities improvement, its impact on muscle strength and quality is still unclear. We aimed to examine postoperative changes in muscle strength and quality and their relationship with body mass index (BMI) changes among adults undergoing BS. To this end, we systematically searched the WoS, PubMed, EBSCO, and Scopus databases. The meta-analyses, which included 24 articles (666 participants), showed that BS reduces absolute lower-limb isometric strength (ES = -0.599; 95% CI = -0.972, -0.226; p = 0.002). Subjects who experienced a more significant reduction in BMI after BS also suffered a higher loss of absolute muscle strength. Similarly, absolute handgrip strength showed a significant decrease (ES = -0.376; 95% CI = -0.630, -0.121; p = 0.004). We found insufficient studies investigating medium- and long-term changes in muscle strength and/or quality after BS. This study provides moderate-quality evidence that BS-induced weight loss can reduce the strength of appendicular muscles in the short term, which should be addressed in management these subjects. More high-quality studies are needed to evaluate the impact of BS on muscle strength and the different domains of muscle quality in the medium and long term (registered on PROSPERO CRD42022332581).

Growth hormone improves insulin resistance in visceral adipose tissue after duodenal-jejunal bypass by regulating adiponectin secretion

BACKGROUND

The mechanism of improvement of type 2 diabetes after duodenal-jejunal bypass (DJB) surgery is not clear.

AIM

To study the morphological and functional changes in adipose tissue after DJB and explore the potential mechanisms contributing to postoperative insulin sensitivity improvement of adipose tissue in a diabetic male rat model.

METHODS

DJB and sham surgery was performed in a-high-fat-diet/streptozotocin-induced diabetic rat model. All adipose tissue was weighed and observed under microscope. Use inguinal fat to represent subcutaneous adipose tissue (SAT) and mesangial fat to represent visceral adipose tissue. RNA-sequencing was utilized to evaluate gene expression alterations adipocytes. The hematoxylin and eosin staining, reverse transcription-quantitative polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay were used to study the changes. Insulin resistance was evaluated by immunofluorescence.

RESULTS

After DJB, whole body blood glucose metabolism and insulin sensitivity in adipose tissue improved. Fat cell volume in both visceral adipose tissue (VAT) and SAT increased. Compared to SAT, VAT showed more significantly functional alterations after DJB and KEGG analysis indicated growth hormone (GH) pathway and downstream adiponectin secretion were involved in metabolic regulation. The circulating GH and adiponectin levels and GH receptor and adiponectin levels in VAT increased. Cytological experiment showed that GH stimulated adiponectin secretion and improve insulin sensitivity.

CONCLUSION

GH improves insulin resistance in VAT in male diabetic rats after receiving DJB, possibly by increasing adiponectin secretion.

Plasma SHBG Levels as an Early Predictor of Response to Bariatric Surgery

BACKGROUND

Obesity is a growing global health problem, and currently, bariatric surgery (BS) is the best solution in terms of sustained total weight loss (TWL). However, a significant number of patients present weight regain (WR) in time. There is a lack of biomarkers predicting the response to BS and WR during the follow-up. Plasma SHBG levels, which are low in obesity, increase 1 month after BS but there is no data of plasma SHBG levels at long term. We performed the present study aimed at exploring the SHBG role in predicting TWL and WR after BS.

METHODS

Prospective study including 62 patients with obesity undergoing BS. Anthropometric and biochemical variables, including SHBG were analyzed at baseline, 1, 6, 12, and 24 months; TWL ≥ 25% was considered as good BS response.

RESULTS

Weight loss nadir was achieved at 12 months post-BS where maximum SHBG increase was reached. Greater than or equal to 25% TWL patients presented significantly higher SHBG increases at the first and sixth months of follow-up with respect to baseline (100% and 150% respectively, p = 0.025), than < 25% TWL patients (40% and 50% respectively, p = 0.03). Also, these presented 6.6% WR after 24 months. The first month SHBG increase predicted BS response at 24 months (OR = 2.71; 95%CI = [1.11-6.60]; p = 0.028) and TWL in the 12th month (r = 0.330, p = 0.012) and the WR in the 24th (r =  - 0.301, p = 0.028).

CONCLUSIONS

Our results showed for the first time that increase in plasma SHBG levels within the first month after BS is a good predictor of TWL and WR response after 2 years.

Identification of myokines susceptible to improve glucose homeostasis after bariatric surgery

IMPORTANCE AND OBJECTIVE

The identification of myokines susceptible to improve glucose homeostasis following bariatric surgery could lead to new therapeutic approaches for type 2 diabetes.

METHODS

Changes in the homeostasis model assessment (HOMA) test were assessed in patients before and 3 months after bariatric surgery. Changes in myokines expression and circulating levels were assessed using real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). Myokines known to regulate glucose homeostasis were identified using literature (targeted study) and putative myokines using RNA-sequencing (untargeted study). A linear regression analysis adjusted for age and sex was used to search for associations between changes in the HOMA test and changes in myokines.

RESULTS

In the targeted study, brain-derived neurotrophic factor (BDNF) expression was upregulated (+30%, P = .006) while BDNF circulating levels were decreased (-12%, P = .001). Upregulated BDNF expression was associated with decreased HOMA of insulin resistance (HOMA-IR) (adjusted estimate [95% confidence interval {CI}]: -0.51 [-0.88 to -0.13], P = .010). Decreased BDNF serum levels were associated with decreased HOMA of beta-cell function (HOMA-B) (adjusted estimate [95% CI] = 0.002 [0.00002-0.0031], P = .046). In the untargeted study, upregulated putative myokines included XYLT1 (+64%, P < .001), LGR5 (+57, P< .001), and SPINK5 (+46%, P < .001). Upregulated LGR5 was associated with decreased HOMA-IR (adjusted estimate [95% CI] = -0.50 [-0.86 to -0.13], P = .009). Upregulated XYLT1 and SPINK5 were associated with increased HOMA of insulin sensitivity (HOMA-S) (respectively, adjusted estimate [95% CI] = 109.1 [28.5-189.8], P = .009 and 16.5 [0.87-32.19], P = .039).

CONCLUSIONS

Improved glucose homeostasis following bariatric surgery is associated with changes in myokines expression and circulating levels. In particular, upregulation of BDNF, XYLT1, SPINK5, and LGR5 is associated with improved insulin sensitivity. These results suggest that these myokines could contribute to improved glucose homeostasis following bariatric surgery.

STUDY REGISTRATION

NCT03341793 on ClinicalTrials.gov (https://clinicaltrials.gov/).

Mechanisms of bariatric surgery for weight loss and diabetes remission

Obesity and type 2 diabetes(T2D) lead to defects in intestinal hormones secretion, abnormalities in the composition of bile acids (BAs), increased systemic and adipose tissue inflammation, defects of branched-chain amino acids (BCAAs) catabolism, and dysbiosis of gut microbiota. Bariatric surgery (BS) has been shown to be highly effective in the treatment of obesity and T2D, which allows us to view BS not simply as weight-loss surgery but as a means of alleviating obesity and its comorbidities, especially T2D. In recent years, accumulating studies have focused on the mechanisms of BS to find out which metabolic parameters are affected by BS through which pathways, such as which hormones and inflammatory processes are altered. The literatures are saturated with the role of intestinal hormones and the gut-brain axis formed by their interaction with neural networks in the remission of obesity and T2D following BS. In addition, BAs, gut microbiota and other factors are also involved in these benefits after BS. The interaction of these factors makes the mechanisms of metabolic improvement induced by BS more complicated. To date, we do not fully understand the exact mechanisms of the metabolic alterations induced by BS and its impact on the disease process of T2D itself. This review summarizes the changes of intestinal hormones, BAs, BCAAs, gut microbiota, signaling proteins, growth differentiation factor 15, exosomes, adipose tissue, brain function, and food preferences after BS, so as to fully understand the actual working mechanisms of BS and provide nonsurgical therapeutic strategies for obesity and T2D.

3-Month Post-Operative Increase in FGF21 is Predictive of One-Year Weight Loss After Bariatric Surgery

PURPOSE

The association between bariatric surgery outcome and blood levels of fibroblast growth factor 21 (FGF21) remains controversial. Many patients displayed stable or decreased FGF21 one year after bariatric surgery. Nevertheless, there is often an early increase FGF21 concentration in the post-surgery period. The aim of this study was to investigate the relationship between 3-month FGF21 response and percentage total weight loss at one year after bariatric surgery.

MATERIALS AND METHODS

In this prospective monocentric study, a total of 144 patients with obesity grade 2-3 were included; 61% of them underwent a sleeve gastrectomy and 39% a Roux-en-Y gastric bypass. Data analysis was carried out to determine the relation between 3-month plasma FGF21 response and weight loss one year after bariatric surgery. Multiple adjustments were done including degree of weight loss after 3 months.

RESULTS

FGF21 significantly increased between baseline and Month 3 (n = 144, p < 10-3), then decreased between Month 3 and Month 6 (n = 142, p = 0.047) and was not different from baseline at Month 12 (n = 142, p = 0.86). The 3-month-FGF21 response adjusted to body weight loss was not different between types of bariatric surgery. The 3-month-FGF21 response was associated to body weight loss at Month 6 (r = -0.19, p = 0.02) and Month 12 (r = -0.34, p < 10-4). After multiple regression analysis, only Month 12 body weight loss remained associated to 3-month FGF21 response (r = -0.3, p = 0.02).

CONCLUSION

This study showed that the magnitude of changes in FGF21 at 3 months after bariatric surgery emerged as an independent predictor of one-year body weight loss irrespective of the type of surgery.

Effects of bariatric surgery and dietary intervention on insulin resistance and appetite hormones over a 3 year period

To examine an impact of three types of bariatric surgery compared with dietary intervention (DIET), on concurrent changes in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and appetite hormones over 3 years. Fifty-five adults were studied during phase of weight loss (0-12 months) and during weight stability (12-36 months) post intervention. Measurements of HOMA-IR, fasting and postprandial PYY and GLP1, adiponectin, CRP, RBP4, FGF21 hormones and dual-Xray absorptiometry were performed throughout the study. All surgical groups achieved significant reductions in HOMA-IR with greatest difference between Roux-en-Y gastric bypass and DIET (- 3.7; 95% CI - 5.4, - 2.1; p = 0.001) at 12-36 months. Initial (0-12 months) HOMA-IR values were no different to DIET after adjustment for the lost weight. During 12-36 months, after controlling for treatment procedure and weight, for every twofold increase in postprandial PYY and adiponectin, HOMA-IR decreased by 0.91 (95% CI - 1.71, - 0.11; p = 0.030) and by 0.59 (95% CI - 1.10, - 0.10; p = 0.023) respectively. Initial, non-sustained changes in RBP4 and FGF21 were not associated with HOMA-IR values. While initial rapid weight loss reduces insulin resistance, the enhanced secretions of PYY and adiponectin may contribute to weight-independent improvements in HOMA-IR during weight stability.Clinical trial registration: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12613000188730.

Mechanisms linking bariatric surgery to adipose tissue, glucose metabolism, fatty liver disease and gut microbiota

PURPOSE

In the last 20 years, bariatric surgery has achieved an important role in translational and clinical research because of obesity comorbidities. Initially, a tool to lose weight, bariatric surgery now has been shown to be involved in several metabolic pathways.

METHODS

We conducted a narrative review discussing the underlying mechanisms that could explain the impact of bariatric surgery and the relationship between obesity and adipose tissue, T2D, gut microbiota, and NAFLD.

RESULTS

Bariatric surgery has an impact in the relation between obesity and type 2 diabetes, but in addition  it induces the white-to-brown adipocyte trans-differentiation, by enhancing thermogenesis. Another issue is the connection of bariatric surgery with the gut microbiota and its role in the complex mechanism underlying weight gain.

CONCLUSION

Bariatric surgery modifies gut microbiota, and these modifications influence lipid metabolism, leading to improvement of non-alcoholic fatty liver disease.

Effects of Peripheral Neural Blocks in Laparoscopic Sleeve Gastrectomy: a Pilot Study on Cognitive Functions in Severe Obese Patients

BACKGROUND

In addition to the analgesic effect, peripheral neural blocks also prevent cognitive impairment and peripheral inflammation induced by surgery. However, it is unknown if there is collateral impact on cognitive improvement after bariatric surgery.

METHODS

In this pilot study, 75 patients with severe obesity for selective laparoscopic sleeve gastrectomy (LSG) were recruited and randomized into three groups (1:1:1) as general anesthesia (GA) group, transverse abdominis plane block (TAPB) group, and quadratus lumborum block (QLB) group. Bilateral TAPB or QLB was performed (0.33% ropivacaine with dexmedetomidine 1 μg/kg) before the standardized general anesthesia. Cognitive test battery was completed before LSG and in 1-month and 3-month follow-up. The levels of peripheral inflammatory cytokines were determined at equivalent time points.

RESULTS

Patients with LSG exhibited massive cognitive improvement in postoperative 3 month without or with TAPB or QLB (P_time < 0.001). Compared to GA, QLB significantly strengthened performance in MoCA (β = 0.56, 95%CI: 0.08, 1.05). IL-6, IL-8, and high-sensitivity CRP significantly verified among three groups. Changes in IL-6 within postoperative 3 months were negatively correlated with MMSE and MoCA, and positively correlated with AVLT-DR for QLB group. Similar correlation was found in the GA group for changes in IL-6 and AVLT-IR.

CONCLUSION

Laparoscopic sleeve gastrectomy ideally improved memory and attention as early as postoperative 1 month. QLB promoted cognitive improvement in MoCA, which was negatively correlated with changes in IL-6. More precise trials are needed to determine the overall effect of peripheral neural block on cognition following bariatric surgery.

Integrative analyses of hub genes and their association with immune infiltration in adipose tissue, liver tissue and skeletal muscle of obese patients after bariatric surgery

Bariatric surgery (BS) is an effective treatment for obesity. Adipose tissue, liver tissue and skeletal muscle are important metabolic tissues. This study investigated hub genes and their association with immune infiltration in these metabolic tissues of obese patients after BS by bioinformatic analysis with Gene Expression Omnibus datasets. Differentially expressed genes (DEGs) were identified, and a protein–protein interaction network was constructed to identify hub genes. As a result, 121 common DEGs were identified and mainly enriched in cytokine–cytokine receptor interactions, chemokine signaling pathway, neutrophil activation and immune responses. Immune cell infiltration analysis showed that the abundance of M1 macrophages was significantly lower in adipose and liver tissue after BS (p<0.05). Ten hub genes (TYROBP, TLR8, FGR, NCF2, HCK, CCL2, LAPTM5, MNDA and S100A9) that were all downregulated after BS were also associated with immune cells. Consistently, results in the validated dataset showed that the expression levels of these hub genes were increased in obese patients and mice, and decreased after BS. In conclusion, this study analysed the potential immune and inflammatory mechanisms of BS in three key metabolic tissues of obese patients, and revealed hub genes associated with immune cell infiltration, thus providing potential targets for obesity treatment.

The emerging role of leptin in obesity-associated cardiac fibrosis: evidence and mechanism

Cardiac fibrosis is a hallmark of various cardiovascular diseases, which is quite commonly found in obesity, and may contribute to the increased incidence of heart failure arrhythmias, and sudden cardiac death in obese populations. As an endogenous regulator of adiposity metabolism, body mass, and energy balance, obesity, characterized by increased circulating levels of the adipocyte-derived hormone leptin, is a critical contributor to the pathogenesis of cardiac fibrosis. Although there are some gaps in our knowledge linking leptin and cardiac fibrosis, this review will focus on the interplay between leptin and major effectors involved in the pathogenesis underlying cardiac fibrosis at both cellular and molecular levels based on the current reports. The profibrotic effect of leptin is predominantly mediated by activated cardiac fibroblasts but may also involve cardiomyocytes, endothelial cells, and immune cells. Moreover, a series of molecular signals with a known profibrotic property is closely involved in leptin-induced fibrotic events. A more comprehensive understanding of the underlying mechanisms through which leptin contributes to the pathogenesis of cardiac fibrosis may open up a new avenue for the rapid emergence of a novel therapy for preventing or even reversing obesity-associated cardiac fibrosis.

Towards harnessing the value of organokine crosstalk to predict the risk for cardiovascular disease in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Importantly, NAFLD increases the risk for cardiovascular disease (CVD). A causal relationship has been substantiated. Given the pandemic proportions of NAFLD, a reliable scoring system for predicting the risk of NAFLD-associated CVD is an urgent medical need. We here review cumulative evidence suggesting that systemically released organokines - especially certain adipokines, hepatokines, and cardiokines - may serve this purpose. The underlying rationale is that these signalers directly communicate between white adipose tissue, liver, and heart as key players in the pathogenesis of NAFLD and resultant CVD events. Moreover, evidence suggests that these organ-specific cytokines are secreted in a biologically predetermined, cascade-like pattern. Consequently, upon pinpointing organokines of relevance, we sketch requirements to establish an algorithm predictive of the CVD risk in patients with NAFLD. Such an algorithm, as to be consolidated in the form of an applicable equation, may be improved continuously by machine learning. To the best of our knowledge, such an option has not yet been considered. Establishing and implementing a reliable algorithm for determining the NAFLD-associated CVD risk has the potential to save many NAFLD patients from life-threatening CVD events.

Neurohormonal Changes in the Gut-Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery

Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut-brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut-brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.

Two-year change in weight status and high carotid intima-media thickness in Chinese children

BACKGROUND

No studies have assessed the association between change in weight status and subclinical cardiovascular outcomes in children.

OBJECTIVE

To examine the association of change in weight status over 2 years with carotid intima-media thickness (cIMT) among Chinese children.

METHODS

A total of 1184 children aged 6-11 years at baseline with complete data were included, and there were 1073 children after excluding those with cIMT ≥ sex- and age-specific 90th percentile values at baseline. Overweight (including obesity) at baseline or follow-up was defined by criteria for overweight and obesity for Chinese school-aged children and adolescents. High cIMT at follow-up was defined as cIMT ≥ age- and sex-specific 90th percentile based on the study population at follow-up.

RESULTS

Compared with children who were in persistent normal-weight group, those in the incident or persistent overweight groups had higher cIMT change (incident overweight: β = 0.0149, p < 0.05; persistent overweight: β = 0.0068, p < 0.05) and had higher odds of high cIMT at follow-up (incident overweight: odds ratio [OR] = 3.58, 95% confidence interval [CI] = 1.34-9.61; persistent overweight: OR = 13.41, 95% CI = 7.58-23.73). In contrast, there was no significant increase in cIMT change (β = 0.0106, p > 0.05) and odds of high cIMT (OR = 2.50, 95% CI = 0.69-9.01) in the resolution group.

CONCLUSION

Children who developed overweight or maintained overweight over 2 years had increased odds of high cIMT, whereas those able to resolve their overweight status had a similar odds of developing high cIMT in childhood at follow-up. These findings highlight the potential role of managing weight status among children to preserve vascular health.

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.

Role of ANGPTL8 in NAFLD Improvement after Bariatric Surgery in Experimental and Human Obesity

Angiopoietin-like protein 8 (ANGPTL8) is an hepatokine altered in several metabolic conditions, such as obesity, type 2 diabetes, dyslipidemia and nonalcoholic fatty liver disease (NAFLD). We sought to explore whether ANGPTL8 is involved in NAFLD amelioration after bariatric surgery in experimental models and patients with severe obesity. Plasma ANGPTL8 was measured in 170 individuals before and 6 months after bariatric surgery. Hepatic ANGPTL8 expression was evaluated in liver biopsies of patients with severe obesity undergoing bariatric surgery with available liver pathology analysis (n = 75), as well as in male Wistar rats with diet-induced obesity subjected to sham operation, sleeve gastrectomy or Roux-en-Y gastric bypass (RYGB) (n = 65). The effect of ANGPTL8 on lipogenesis was assessed in human HepG2 hepatocytes under palmitate-induced lipotoxic conditions. Plasma concentrations and hepatic expression of ANGPTL8 were increased in patients with obesity-associated NAFLD in relation to the degree of hepatic steatosis. Sleeve gastrectomy and RYGB improved hepatosteatosis and reduced the hepatic ANGPTL8 expression in the preclinical model of NAFLD. Interestingly, ANGPTL8 inhibited steatosis and expression of lipogenic factors (PPARG2, SREBF1, MOGAT2 and DGAT1) in palmitate-treated human hepatocytes. Together, ANGPTL8 is involved in the resolution of NAFLD after bariatric surgery partially by the inhibition of lipogenesis in steatotic hepatocytes.

Body Composition, Basal Metabolic Rate and Leptin in Long-Term Weight Regain After Roux-en-Y Gastric Bypass Are Similar to Pre-surgical Obesity

PURPOSE

The purpose of this study is to evaluate the relationship between body composition, basal metabolic rate (BMR), and serum concentrations of leptin with long-term weight regain after Roux-en-Y gastric bypass (RYGB) and compare it with obesity before surgery.

MATERIALS AND METHODS

Prospective longitudinal analytical study. Three groups were formed: individuals 60 months post RYGB, with weight regain (G1) and without it (G2), and individuals with obesity who had not undergone bariatric surgery (G3). Body fat (BF), body fat mass (BFM), visceral fat (VF), fat-free mass (FFM), skeletal muscle mass (SMM), and BMR were assessed by octapolar and multi-frequency electrical bioimpedance. Fasting serum concentrations of leptin were measured.

RESULTS

Seventy-two individuals were included, 24 in each group. Higher means of BF, BFM, VF, and leptin levels were observed in G1, when compared to G2 (BF: 47.5 ± 5.6 vs. 32.0 ± 8.0, p < 0.05; FBM: 47.8 ± 11.6 vs. 23.9 ± 7.0, p < 0.05; VF: 156.8 ± 30.2 vs. 96.1 ± 23.8, p < 0.05; leptin: 45,251.2 pg/mL ± 20,071.8 vs. 11,525.7 pg/mL ± 9177.5, p < 0.000). G1 and G2 did not differ in FFM, SMM, and BMR. G1 and G3 were similar according to BF, FFM, BMR, and leptin levels. Body composition, but not leptin, was correlated with %weight regain in G1 (FBM: r = 0.666, p < 0.000; BF: r = 0.428, p = 0.037; VF: r = 0.544, p = 0.006).

CONCLUSION

Long-term weight regain after RYGB is similar to pre-surgical obesity in body composition, BMR, and leptin concentrations, indicating relapse of metabolic and hormonal impairments associated with excessive body fat.

Adipokines, Myokines, and Hepatokines: Crosstalk and Metabolic Repercussions

Adipose, skeletal, and hepatic muscle tissues are the main endocrine organs that produce adipokines, myokines, and hepatokines. These biomarkers can be harmful or beneficial to an organism and still perform crosstalk, acting through the endocrine, paracrine, and autocrine pathways. This study aims to review the crosstalk between adipokines, myokines, and hepatokines. Far beyond understanding the actions of each biomarker alone, it is important to underline that these cytokines act together in the body, resulting in a complex network of actions in different tissues, which may have beneficial or non-beneficial effects on the genesis of various physiological disorders and their respective outcomes, such as type 2 diabetes mellitus (DM2), obesity, metabolic syndrome, and cardiovascular diseases (CVD). Overweight individuals secrete more pro-inflammatory adipokines than those of a healthy weight, leading to an impaired immune response and greater susceptibility to inflammatory and infectious diseases. Myostatin is elevated in pro-inflammatory environments, sharing space with pro-inflammatory organokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), resistin, and chemerin. Fibroblast growth factor FGF21 acts as a beta-oxidation regulator and decreases lipogenesis in the liver. The crosstalk mentioned above can interfere with homeostatic disorders and can play a role as a potential therapeutic target that can assist in the methods of diagnosing metabolic syndrome and CVD.

Effects of bariatric surgery on lipid-lipoprotein profile

Most patients with severe obesity will present some lipid-lipoprotein abnormalities. The atherogenic dyslipidemia associated with severe obesity is characterized by elevated fasting and postprandial triglyceride levels, low high-density lipoprotein cholesterol concentrations, and increased proportion of small and dense low-density lipoproteins. Bariatric surgery has been proven safe and successful in terms of long-term weight loss and improvement in obesity co-existing metabolic conditions including lipid-lipoprotein abnormalities. Nevertheless, bariatric surgery procedures are not all equivalent. We conducted a comprehensive critical analysis of the literature related to severe obesity, bariatric surgery and lipid-lipoprotein metabolism/profile. In this review, we described the metabolic impacts of different bariatric surgery procedures on the lipid-lipoprotein profile, and the mechanisms linking bariatric surgery and dyslipidemia remission based on recent epidemiological, clinical and preclinical studies. Further mechanistic studies are essential to assess the potential of bariatric/metabolic surgery in the management of lipid-lipoprotein abnormalities associated with severe obesity. Understanding the beneficial effects of various bariatric surgery procedures on the lipid-lipoprotein metabolism and profile may result in a wider acceptance of this strategy as a long-term metabolic treatment of lipid-lipoprotein abnormalities in severe obesity and help clinician to develop an individualized and optimal approach in the management of dyslipidemia associated with severe obesity. BRIEF SUMMARY: Abnormal lipid-lipoprotein profile is frequent in patients with severe obesity. Significant improvements in lipid-lipoprotein profile following bariatric surgery occur early in the postoperative period, prior to weight loss, and persists throughout the follow-up. The mechanisms that facilitate the remission of dyslipidemia after bariatric surgery, may involve positive effects on adipose tissue distribution/function, insulin sensitivity, liver fat content/function and lipid-lipoprotein metabolism.

Characterization and Treatment of Inflammation and Insulin Resistance in Obese Adipose Tissue

Adipose tissue is the largest energy storage and protection organ. It is distributed subcutaneously and around the internal organs. It regulates metabolism by storing and releasing fatty acids and secreting adipokines. Excessive nutritional intake results in adipocyte hypertrophy and proliferation, leading to local hypoxia in adipose tissue and changes in the release of adipokines. These lead to recruit of more immune cells into adipose tissue and release of inflammatory signaling factors. Excess free fatty acids and inflammatory factors interfere with intracellular insulin signaling. In this review, we summarize the characteristics of obese adipose tissue and analyze how its inflammation causes insulin resistance. We further discuss the latest clinical research progress on the control of insulin resistance and inflammation resulting from obesity through anti-inflammatory therapy and bariatric surgery. Our review shows that targeted anti-inflammatory therapy is of great significance for obese patients with insulin resistance.