Mechanisms for the metabolic success of bariatric surgery

Significant Promising Effects of Bariatric Surgery on the Biochemical Control of Glycemia and Lipidemia in Diabetic Patients in Western Saudi Arabia: A Tertiary Center Experience and a Retrospective Study

BACKGROUND

The prevalence of obesity has increased globally and is associated with many comorbidities such as type 2 diabetes and fatty liver and cardiovascular diseases. Bariatric surgery is considered an effective intervention for achieving weight loss and controlling lipidemia and glycemia.

OBJECTIVES

This Saudi retrospective observational study evaluates the clinical and biochemical benefits following bariatric surgery to obese diabetic patients.  Methodology: After gaining ethical committee approval, data was collected from the patients' medical records at a tertiary medical center (King Fahad General Hospital, Al-Madinah Al-Munawwarah, Saudi Arabia). The total sample size was 61 patients, of whom 78.33% (n=48) had a body mass index (BMI) of 40 or greater (obese class III).

RESULTS

Following bariatric surgery, there were statistically significant reductions (p<0.001) in BMI and HbA1C (decreased from 45.53±7.791 kg/m2 and 7.9±1.82% to 33.42±6.18 kg/m2 and 6.06±1.35%, respectively, after surgery). Likewise, significant reductions (p<0.001) occurred to serum total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides that decreased from 234.4±26.7 mg/dl, 152.2±19.4 mg/dl, and 187.3±24.6 mg/dl to 158.4±17.3 mg/dl, 95.6±15.7 mg/dl, and 132.5±19.5 mg/dl, respectively. Interestingly, serum high-density lipoprotein (HDL) significantly increased (p<0.001) from 43.8±6.2 mg/dl to 52.3±4.6 mg/dl. Using the novel clinical therapeutic index, bariatric surgery decreased BMI by about 26.6%. Using the novel biochemical therapeutic index, bariatric surgery decreased HbA1C, serum total cholesterol, serum LDL cholesterol, and serum triglycerides by about 22.99%, 32.42%, 37.18%, and 29.26%, respectively, while serum HDL increased by about 19.4%.

CONCLUSION

Bariatric surgery is an effective intervention for obese diabetic patients resulting in weight loss, better control of diabetes and hyperlipidemia, and the metabolic profile. It is also recommended in Saudi Arabia for the high prevalence of obesity and diabetes mellitus.

Associations between the gut microbiome and metabolic, inflammatory, and appetitive effects of sleeve gastrectomy

The complex and multifactorial etiology of obesity creates challenges for its effective long-term management. Increasingly, the gut microbiome is reported to play a key role in the maintenance of host health and wellbeing, with its dysregulation associated with chronic diseases such as obesity. The gut microbiome is hypothesized to contribute to obesity development and pathogenesis via several pathways involving food digestion, energy harvest and storage, production of metabolites influencing satiety, maintenance of gut barrier integrity, and bile acid metabolism. Moreover, the gut microbiome likely contributes to the metabolic, inflammatory, and satiety benefits and sustained weight-loss effects following bariatric procedures such as sleeve gastrectomy. While the field of gut microbiome research in relation to obesity and sleeve gastrectomy outcomes is largely in its infancy, the gut microbiome nonetheless holds great potential for understanding some of the mechanisms behind sleeve gastrectomy outcomes as well as for optimizing post-surgery benefits. This review will explore the current literature within the field as well as discuss the current limitations, including the small sample size, variability in methodological approaches, and lack of associative data, which need to be addressed in future studies.

Long-term cancer outcomes after bariatric surgery

OBJECTIVE

Obesity is associated with increased cancer risk. Because of the substantial and sustained weight loss following bariatric surgery, postsurgical patients are ideal to study the association of weight loss and cancer.

METHODS

Retrospectively (1982-2019), 21,837 bariatric surgery patients (surgery, 1982-2018) were matched 1:1 by age, sex, and BMI with a nonsurgical comparison group. Procedures included gastric bypass, gastric banding, sleeve gastrectomy, and duodenal switch. Primary outcomes included cancer incidence and mortality, stratified by obesity- and non-obesity-related cancers, sex, cancer stage, and procedure.

RESULTS

Bariatric surgery patients had a 25% lower risk of developing any cancers compared with a nonsurgical comparison group (hazard ratio [HR] 0.75; 95% CI 0.69-0.81; p < 0.001). Cancer incidence was lower among female (HR 0.67; 95% CI 0.62-0.74; p < 0.001) but not male surgery patients, with the HR lower for females than for males (p < 0.001). Female surgery patients had a 41% lower risk for obesity-related cancers (i.e., breast, ovarian, uterine, and colon) compared with nonsurgical females (HR 0.59; 95% CI 0.52-0.66; p < 0.001). Cancer mortality was significantly lower after surgery in females (HR 0.53; 95% CI 0.44-0.64; p < 0.001).

CONCLUSIONS

Bariatric surgery was associated with lower all-cancer and obesity-related cancer incidence among female patients. Cancer mortality was significantly lower among females in the surgical group versus the nonsurgical group.

Long-term all-cause and cause-specific mortality for four bariatric surgery procedures

OBJECTIVE

This retrospective study incorporated long-term mortality results after different bariatric surgery procedures and for multiple age at surgery groups.

METHODS

Participants with bariatric surgery (surgery) and without (non-surgery) were matched (1:1) for age, sex, BMI, and surgery date with a driver license application/renewal date. Mortality rates were compared by Cox regression, stratified by sex, surgery type, and age at surgery.

RESULTS

Participants included 21,837 matched surgery and non-surgery pairs. Follow-up was up to 40 years (mean [SD], 13.2 [9.5] years). All-cause mortality was 16% lower in surgery compared with non-surgery groups (hazard ratio, 0.84; 95% CI: 0.79-0.90; p < 0.001). Significantly lower mortality after bariatric surgery was observed for both females and males. Mortality after surgery versus non-surgery decreased significantly by 29%, 43%, and 72% for cardiovascular disease, cancer, and diabetes, respectively. The hazard ratio for suicide was 2.4 times higher in surgery compared with non-surgery participants (95% CI: 1.57-3.68; p < 0.001), primarily in participants with ages at surgery between 18 and 34 years.

CONCLUSIONS

Reduced all-cause mortality was durable for multiple decades, for multiple bariatric surgical procedures, for females and males, and for greater than age 34 years at surgery. Rate of death from suicide was significantly higher in surgery versus non-surgery participants only in the youngest age at surgery participants.

The role of bariatric and metabolic surgery in the development, diagnosis, and treatment of endometrial cancer

The obesity pandemic continues to contribute to a worsening burden of disease worldwide. The link between obesity and diseases such as diabetes, cardiovascular disease, and cancer has been well established, yet most patients living with obesity remain untreated or undertreated. Metabolic and bariatric surgery is the most effective and durable treatment for obesity, is safe, and may have a protective benefit with respect to cancer incidence. In this review, an overview of the link between obesity, metabolic surgery, and cancer is discussed with emphasis on indications for endometrial cancer, the malignancy most strongly associated with obesity. Considerable evidence from retrospective and prospective cohort studies supports a decreased risk of endometrial cancer in patients with obesity who undergo bariatric surgery compared with nonsurgical controls. Survivors of endometrial cancer are at increased risk of poor health outcomes associated with obesity, and women with endometrial cancer are more likely to die of cardiovascular disease and other obesity-related illnesses than of the malignancy itself. Recent advances in anticancer drug therapies have targeted pathways that may also be therapeutically altered with metabolic surgery. Metabolic surgery has significant potential to enter the treatment paradigm for endometrial cancer, and gynecologic oncologist visits present an opportunity to identify patients who may benefit the most.

Gut Factors Mediating the Physiological Impact of Bariatric Surgery

Despite decades of obesity research and various public health initiatives, obesity remains a major public health concern. Our most drastic but most effective treatment of obesity is bariatric surgery with weight loss and improvements in co-morbidities, including resolution of type 2 diabetes (T2D). However, the mechanisms by which surgery elicits metabolic benefits are still not well understood. One proposed mechanism is through signals generated by the intestine (nutrients, neuronal, and/or endocrine) that communicate nutrient status to the brain. In this review, we discuss the contributions of gut-brain communication to the physiological regulation of body weight and its impact on the success of bariatric surgery. Advancing our understanding of the mechanisms that drive bariatric surgery-induced metabolic benefits will ultimately lead to the identification of novel, less invasive strategies to treat obesity.

The risk of inflammatory bowel disease after bariatric surgery

BACKGROUND

The association between bariatric surgery and new onset of inflammatory bowel disease has so far only been sparsely studied and with conflicting results.

OBJECTIVES

To investigate the association between bariatric surgery and inflammatory bowel disease in a large population-based cohort.

SETTING

Nationwide in Sweden.

METHODS

This population-based retrospective cohort study included Swedish individuals registered in the Scandinavian Obesity Surgery Registry who underwent primary Roux-en-Y gastric bypass or sleeve gastrectomy during 2007-2018. Ten control individuals from the general population were matched according to age, sex, and region of residence at time of exposure. The study population was followed until 2019 with regard to the development of inflammatory bowel disease. Cox proportional hazards models were used to compare disease-free survival time between subgroups and control individuals for each outcome.

RESULTS

The final cohort consisted of 64,188 exposed individuals with a total follow-up of 346,860 person-years and 634,530 controls with total follow-up of 3,444,186 person-years. Individuals who underwent Roux-en-Y-gastric bypass had an increased risk of later development of Crohn's disease (hazard ratio [HR] 1.8, 95% CI 1.5-2.2) and unclassified inflammatory bowel disease (HR 2.7, 95% CI 2.0-3.7) but not ulcerative colitis (HR .9, 95% CI .8-1.1) compared with control individuals, whereas individuals who underwent sleeve gastrectomy had an increased risk of ulcerative colitis (HR 1.8, 95% CI 1.1-3.1) but not Crohn's disease (HR .8, 95% CI .3-2.1) and unclassified inflammatory bowel disease (HR 2.5, 95% CI .8-7.8).

CONCLUSIONS

Roux-en-Y gastric bypass was associated with increased risk of Crohn's disease and unclassified inflammatory bowel disease, whereas sleeve gastrectomy was associated with increased risk of ulcerative colitis only.

Associations Between Video Evaluations of Surgical Technique and Outcomes of Laparoscopic Sleeve Gastrectomy

Importance

In any surgical procedure, various aspects of technique may affect patient outcomes. As new procedures enter practice, it is difficult to evaluate the association of each aspect of technique with patient outcomes.

Objective

To examine the associations between technique and outcomes in laparoscopic sleeve gastrectomy.

Design, Setting, and Participants

In this cohort study of bariatric surgery programs participating in a statewide surgical quality improvement collaborative, 30 surgeons submitted intraoperative videos from representative sleeve gastrectomies performed on 6915 patients with morbid obesity. These videos were reviewed by blinded peer surgeons on key technical elements, and 605 reviews were linked to sleeve gastrectomy outcomes of all of the surgeons' patients from January 1, 2015, to December 31, 2016.

Exposures

Surgeons' technical approaches to 5 controversial aspects of laparoscopic sleeve gastrectomy: dissection of the proximal stomach, sleeve caliber, sleeve anatomy, staple line reinforcement, and leak testing.

Main Outcomes and Measures

The 30-day outcomes were rate of postoperative hemorrhage and staple line leak. The 1-year outcomes were percentage of total weight lost and reflux severity (Gastroesophageal Reflux Disease Health-Related Quality of Life instrument).

Results

A total of 30 surgeons submitted 46 videos of operations performed on 6915 patients (mean [SD] age, 45.4 [11.7] years; 5494 [79.5%] female; 4706 [68.1%] White). Complete dissection of the proximal stomach was associated with reduced hemorrhage rates (higher ratings for complete mobilization of fundus were associated with a decrease in hemorrhage rate from 2.1% [25th percentile] to 1.0% [75th percentile], P = .01; higher ratings for visualization of the left crus were associated with a decrease in hemorrhage rate from 1.5% to 0.94%, P = .006; and higher ratings for complete division of the short gastrics were associated with a decrease in hemorrhage rate from 2.8% to 1.2%, P = .03). The reduction in hemorrhage rates came at the expense of higher leak rates (higher ratings for complete mobilization of fundus were associated with an increase in leak rate from 0.05% [25th percentile] to 0.16% [75th percentile], P < .001; higher ratings for visualization of the left crus were associated with an increase in leak rate from 0.1% to 0.2%, P = .003; and higher ratings for complete division of the short gastrics were associated with an increase in leak rate from 0.02% to 0.1%, P = .01). Surgeons who stapled more tightly to the bougie had smaller decreases in reflux than those who stapled less tightly (-2.0 to -1.3 on a 50-point scale, P = .002). Staple line reinforcement (buttressing and oversewing) was associated with a small (2 of 1000 cases) decrease in hemorrhage rates. Staple line buttressing was also associated with a similarly small increase in leak rates (1 of 1000 cases). Leak testing was associated with a statistically insignificant change in the staple line leak rate (0.16%-0.22%, P = .47).

Conclusions and Relevance

Variations in surgical technique can be measured by video review and are associated with differences in patient outcomes.

The Phantom Satiation Hypothesis of Bariatric Surgery

The excitation of vagal mechanoreceptors located in the stomach wall directly contributes to satiation. Thus, a loss of gastric innervation would normally be expected to result in abrogated satiation, hyperphagia, and unwanted weight gain. While Roux-en-Y-gastric bypass (RYGB) inevitably results in gastric denervation, paradoxically, bypassed subjects continue to experience satiation. Inspired by the literature in neurology on phantom limbs, I propose a new hypothesis in which damage to the stomach innervation during RYGB, including its vagal supply, leads to large-scale maladaptive changes in viscerosensory nerves and connected brain circuits. As a result, satiation may continue to arise, sometimes at exaggerated levels, even in subjects with a denervated or truncated stomach. The same maladaptive changes may also contribute to dysautonomia, unexplained pain, and new emotional responses to eating. I further revisit the metabolic benefits of bariatric surgery, with an emphasis on RYGB, in the light of this phantom satiation hypothesis.

Weight Loss After Laparoscopic Sleeve Gastrectomy Ameliorates the Cardiac Remodeling in Obese Chinese

This study aimed to investigate the impact of weight loss after laparoscopic sleeve gastrectomy (LSG) on cardiac structural and functional remodeling in obese Chinese. A total of 44 obese participants were enrolled consecutively. The physical, laboratory, electrocardiographic, and echocardiographic parameters of pre-and postoperative were recorded. The average follow-up time was 12.28 ± 5.80 months. The body mass index (BMI) of the patients with obesity was decreased from 41.6 ± 7.44 to 30.3 ± 5.73kg/m² (P<0.001) after LSG. The systolic and diastolic blood pressure of the subjects was significantly reduced from 137.9 ± 15.7mmHg to 123.0 ± 16.0 and 83.4 ± 10.8 to 71.3 ± 11.7mmHg (P<0.001), respectively. The levels of fasting insulin and fasting blood glucose were significantly decreased (38.8 ± 32.1 to 8.43 ± 4.16 mU/L, P<0.001; 6.95 ± 2.59 to 4.64 ± 0.50mmol/L, P<0.001). Total cholesterol (TC, 4.66 ± 0.84 to 4.23 ± 0.75mmol/L, P<0.001) and triglyceride (TG, 1.92 ± 1.21 to 0.85 ± 0.30mmol/L, P<0.001) decreased significantly. Cardiovascular geometric parameters including aortic sinus diameter (ASD, 32.9 ± 2.83mm to 32.0 ± 3.10mm, P<0.05), left atrial diameter (LAD, 38.8 ± 4.03 to 36.2 ± 4.12mm, P<0.001), and interventricular septum thickness(IVS, 10.2 ± 0.93 to 9.64 ± 0.89mm, P<0.001) were significantly reduced. The ratio of weight loss (RWL) was positively correlated with the changes of LAD. The change of IVS was negatively correlated with the change of fasting blood glucose (GLU). Weight loss after LSG could effectively improve cardiac structural, but not functional, abnormality in obese Chinese.

Impacts of Different Modes of Bariatric Surgery on Plasma Levels of Hepassocin in Patients with Diabetes Mellitus

Background: Hepassocin is a liver-derived protein and its serum concentrations significantly increase in diabetes and fatty liver patients. Hepassocin is also a biomarker for diabetes and fatty liver; therefore, we aimed to investigate the impacts of different types of bariatric surgery on hepassocin plasma levels in obese patients with diabetes, and to determine if hepassocin could be a potential new marker for monitoring the effects of bariatric surgery and a treatment target. Methods: Overall, 12 patients undergoing gastric bypass (GB), 10 patients undergoing sleeve gastrectomy (SG) and 11 patients undergoing duodeno-jejunal bypass with sleeve gastrectomy (DJB-SG) were enrolled. Fasting hepassocin levels were measured at baseline, three, 12, and 24 months after surgery. Results: All the three groups significantly decreased their body mass index, waist-to-hip ratio, a body shape index (ABSI), triglycerides, fasting blood sugar, hemoglobin A1c, C-peptide levels and homeostasis model assessment of insulin resistance 24 months after surgery. There were no significant changes in hepassocin levels, even 24 months after the three surgeries. Hepassocin had a significant negative relationship with the ABSI (p< 0.001) 24 months after the SG. Conclusions: Neither GB, SG, nor DJB-SG altered plasma hepassocin levels in diabetic patients up to 24 months after surgery. The use of hepassocin in clinical settings requires more investigation.

Bile-ology: from bench to bedside

Bile acids (BAs) are originally known as detergents essential for the digestion and absorption of lipids. In recent years, extensive research has unveiled new functions of BAs as gut hormones that modulate physiological and pathological processes, including glucose and lipid metabolism, energy expenditure, inflammation, tumorigenesis, cardiovascular disease, and even the central nervous system in addition to cholesterol homeostasis, enterohepatic protection and liver regeneration. BAs are closely linked with gut microbiota which might explain some of their crucial roles in organs. The signaling actions of BAs can also be mediated through specific nuclear receptors and membrane-bound G protein-coupled receptors. Several pharmacological agents or bariatric surgeries have demonstrated efficacious therapeutic effects on metabolic diseases through targeting BA signaling. In this mini-review, we summarize recent advances in bile-ology, focusing on its translational studies.