Gastric bypass specifically impairs liver parameters as compared with sleeve gastrectomy, independently of evolution of metabolic disorders

Subcutaneous Stromal Cells and Visceral Adipocyte Size Are Determinants of Metabolic Flexibility in Obesity and in Response to Weight Loss Surgery

Adipose tissue (AT) expansion either through hypertrophy or hyperplasia is determinant in the link between obesity and metabolic alteration. The present study aims to profile the unhealthy subcutaneous and visceral AT (SAT, VAT) expansion in obesity and in the outcomes of bariatric surgery (BS). The repartition of adipocytes according to diameter and the numbers of progenitor subtypes and immune cells of SAT and VAT from 161 obese patients were determined by cell imaging and flow cytometry, respectively. Associations with insulin resistance (IR) prior to BS as well as with the loss of excessive weight (EWL) and IR at 1 and 3 years post-BS were studied; prior to BS, SAT and VAT, unhealthy expansions are characterized by the accumulation of adipogenic progenitors and CD4+ T lymphocytes and by adipocyte hypertrophy and elevated macrophage numbers, respectively. Such SAT stromal profile and VAT adipocyte hypertrophy are associated with adverse BS outcomes. Finally, myofibrogenic progenitors are a common determinant of weight and IR trajectories post-BS; the study suggests that adipogenesis in SAT and adipocyte hypertrophy in VAT are common determinants of metabolic alterations with obesity and of the weight loss and metabolic response to bariatric surgery. The data open up new avenues to better understand and predict individual outcomes in response to changes in energy balance.

Prospective comparison of transient elastography, MRI and serum scores for grading steatosis and detecting non-alcoholic steatohepatitis in bariatric surgery candidates

Background & Aims

Tools for the non-invasive diagnosis of non-alcoholic steatohepatitis (NASH) in morbidly obese patients with suspected non-alcoholic fatty liver disease (NAFLD) are an unmet clinical need. We prospectively compared the performance of transient elastography, MRI, and 3 serum scores for the diagnosis of NAFLD, grading of steatosis and detection of NASH in bariatric surgery candidates.

Methods

Of 186 patients screened, 152 underwent liver biopsy, which was used as a reference for NAFLD (steatosis [S]>5%), steatosis grading and NASH diagnosis. Biopsies were read by a single expert pathologist. MRI-based proton density fat fraction (MRI-PDFF) was measured in an open-bore, vertical field 1.0T scanner and controlled attenuation parameter (CAP) was measured by transient elastography, using the XL probe. Serum scores (SteatoTest, hepatic steatosis index and fatty liver index) were also calculated.

Results

The applicability of MRI was better than that of FibroScan (98% vs. 79%; p <0.0001). CAP had AUROCs of 0.83, 0.79, 0.73 and 0.69 for S>5%, S>33%, S>66% and NASH, respectively. Transient elastography had an AUROC of 0.80 for significant fibrosis (F0-F1 vs. F2-F3). MRI-PDFF had AUROCs of 0.97, 0.95, 0.92 and 0.84 for S>5%, S>33%, S>66% and NASH, respectively. When compared head-to-head in the 97 patients with all valid tests available, MRI-PDFF outperformed CAP for grading steatosis (S>33%, AUROC 0.97 vs. 0.78; p <0.0003 and S>66%, AUROC 0.93 vs. 0.75; p = 0.0015) and diagnosing NASH (AUROC 0.82 vs. 0.68; p = 0.0056). When compared in "intention to diagnose" analysis, MRI-PDFF outperformed CAP, hepatic steatosis index and fatty liver index for grading steatosis (S>5%, S>33% and S>66%).

Conclusion

MRI-PDFF outperforms CAP for diagnosing NAFLD, grading steatosis and excluding NASH in morbidly obese patients undergoing bariatric surgery.

Lay summary

Non-invasive tests for detecting fatty liver and steatohepatitis, the active form of the disease, have not been well studied in obese patients who are candidates for bariatric surgery. The most popular tests for this purpose are Fibroscan, which can be used to measure the controlled attenuation parameter (CAP), and magnetic resonance imaging, which can be used to measure the proton density fat fraction (MRI-PDFF). We found that, when taking liver biopsy as a reference, MRI-PDFF performed better than CAP for detecting and grading fatty liver as well as excluding steatohepatitis in morbidly obese patients undergoing bariatric surgery.

Behavior of Iron and Ferritin After Bariatric Surgery in Patients With and Without Hepatic Steatosis

BACKGROUND

Iron deficiency and hepatic steatosis are common in bariatric surgery patients. Steatosis can falsely elevate ferritin values even in presence of iron deficiency. This study aims to assess the influence of hepatic steatosis on iron deficiency and replacement therapy after bariatric surgery.

METHODS

Seventy-nine individuals undergoing gastric bypass have been studied at 4 time points (preoperative and 1, 3, and 6 months after surgery). Weight, body mass index (BMI), iron, ferritin, vitamin B12, folate, hemoglobin, gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and use of iron replacement were recorded.

RESULTS

Forty-two individuals (53%) had moderate/severe steatosis assessed by ultrasound. No differences were seen in iron profile and replacement therapy features compared to individuals with no/mild steatosis both in the preoperative and postoperative periods. Mixed model analysis showed ferritin levels to be higher in the moderate/severe steatosis group than in no/mild steatosis at the 6th month (139 ± 131 vs. 60.9 ± 49.8, p < 0.05). Values in both groups were lower than baseline, with p < 0.0001. The same was observed with serum iron (92.1 ± 39.6 moderate/severe steatosis vs. 68.6 ± 33.4 no/mild steatosis, p < 0.001; p from baseline < 0.01 for both). GGT was higher in moderate/severe steatosis in the 3rd month (38.8 ± 40.5 vs. 28.8 ± 20.8, p < 0.05; p from baseline < 0.0001 for both).

CONCLUSIONS

Ferritin levels were consistently higher in individuals with steatosis in the follow-up of bariatric surgery, but no apparent implication on the diagnosis of iron deficiency and in the prescription of replacement therapy was demonstrated at 6 months of follow-up. Longer studies are probably necessary to investigate this matter.

Gastric Bypass Compared with Sleeve Gastrectomy for Nonalcoholic Fatty Liver Disease: a Systematic Review and Meta-analysis

The effects of bariatric procedures on nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) remain unclear. A systematic review and meta-analysis was performed to compare the impact of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on NAFLD/NASH. Patients submitted to RYGB presented significant reduction of steatohepatitis (RD: 0.53; 95% CI 0.33 to 0.74) and fibrosis (RD: 0.26; 95% CI 0.14 to 0.37). SG caused a significant reduction of steatohepatitis (RD: 0.42; 95% CI 0.27 to 0.57), but not of fibrosis (RD: 0.20; 95% CI -0.00 to 0.39). The NAFLD Activity Score was significantly improved after both procedures, as well as biochemical tests. No difference was found between RYGB and SG regarding the histopathological outcomes. SG and RYGB are equivalently effective for treating NAFLD/NASH.

Nonalcoholic Fatty Liver Disease in Adults: Current Concepts in Etiology, Outcomes, and Management

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disease, extending from simple steatosis to inflammation and fibrosis with a significant risk for the development of cirrhosis. It is highly prevalent and is associated with significant adverse outcomes both through liver-specific morbidity and mortality but, perhaps more important, through adverse cardiovascular and metabolic outcomes. It is closely associated with type 2 diabetes and obesity, and both of these conditions drive progressive disease toward the more advanced stages. The mechanisms that govern hepatic lipid accumulation and the predisposition to inflammation and fibrosis are still not fully understood but reflect a complex interplay between metabolic target tissues including adipose and skeletal muscle, and immune and inflammatory cells. The ability to make an accurate assessment of disease stage (that relates to clinical outcome) can also be challenging. While liver biopsy is still regarded as the gold-standard investigative tool, there is an extensive literature on the search for novel noninvasive biomarkers and imaging modalities that aim to accurately reflect the stage of underlying disease. Finally, although no therapies are currently licensed for the treatment of NAFLD, there are interventions that appear to have proven efficacy in randomized controlled trials as well as an extensive emerging therapeutic landscape of new agents that target many of the fundamental pathophysiological processes that drive NAFLD. It is highly likely that over the next few years, new treatments with a specific license for the treatment of NAFLD will become available.

Impact of sleeve gastrectomy and Roux-en-Y gastric bypass on biopsy-proven non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD)/steatohepatitis (NASH) is the hepatic manifestation of metabolic syndrome. Our aim was to study the long-term effects of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on NAFLD/NASH.

METHODS

Between 2008 and 2015, 3813 patients had an intraoperative liver biopsy performed at the time of primary RYGB and SG at a single academic center. Utilizing strict inclusion criteria, 487 patients with biopsy-proven NAFLD who had abnormal alanine aminotransferase (ALT) or aspartate aminotransferase (AST) values (≥ 40 IU/L) at baseline were identified. Matching of SG to RYGB patients (1:4) was performed via logistic regression and propensity scores adjusting for clinical and liver histological characteristics. Changes in liver function tests (LFTs) at least 1 year after surgery were compared to baseline values and between the surgical groups.

RESULTS

A total of 310 (weighted) patients (SG n = 62, and RYGB n = 248) with a median follow-up time of 4 years (range, 1-10) were included in the analysis. The distribution of covariates was well-balanced after propensity matching. In 84% of patients, LFT values normalized after bariatric surgery at the last follow-up time. The proportions of patients having normalized LFT values did not differ significantly between the SG and RYGB groups (82% vs. 84%, p = 0.66). The AST decreased from (SG: 49.1 ± 21.5 vs. RYGB: 49.3 ± 22.0, p = 0.93) at baseline to (SG: 28.0 ± 16.5 vs. RYGB: 26.5 ± 15.5, p = 0.33) at the last follow-up. Similarly, a significant reduction in ALT values from (SG: 61.7 ± 30.0 vs. RYGB 59.4 ± 24.9, p = 0.75) at baseline to (SG: 27.2 ± 21.5 vs. RYGB: 26.1 ± 19.2, p = 0.52) at the last follow-up was observed.

CONCLUSIONS

In patients with biopsy-proven NAFLD/NASH, abnormal LFTs are normalized in most SG and RYGB patients by the end of the first postoperative year and remain normal until the last follow-up. This study also suggests that both bariatric procedures are similarly effective in improving liver function.

Validation of biochemical scores for liver steatosis before and 1 year after sleeve gastrectomy

BACKGROUND

Bariatric surgery is a potential treatment for liver steatosis in morbidly obese patients, showing an improvement in approximately 90% of cases of fatty liver after surgery. Liver biopsy is the gold standard method to monitor liver steatosis. Imaging tests, such as magnetic resonance (MR) spectroscopy, have shown a good accuracy in the diagnosis of liver steatosis. Several biochemical markers have been proposed as diagnostic alternatives to evaluate fatty liver.

OBJECTIVES

The aim of this study was to analyze the potential of different biochemical markers for evaluating liver steatosis in morbidly obese patients before and after undergoing sleeve gastrectomy.

SETTING

Garcilaso Clinic, Madrid, Spain.

METHODS

A prospective observational study of patients undergoing sleeve gastrectomy was performed. Diverse biochemical markers were assessed and correlated with MR spectroscopy as the diagnostic method for liver steatosis.

RESULTS

One hundred consecutive patients were included. Twelve months after surgery, mean body mass index was 28.3 ± 3.7 kg/m² and mean excess weight loss 82.5% ± 17.8%. Preoperatively, 67% of the patients had liver steatosis and 12 months after surgery the steatosis rate was reduced to 23%, as measured by MR spectroscopy. A significant direct correlation could only be observed between the percentage of lipid content, determined by MR spectroscopy and the liver fat score, at baseline and in the preoperative score. A cut-off point for liver fat score to determine the presence of liver steatosis was established at 1.22, for baseline and postoperative determinations.

CONCLUSION

The liver fat score is the most accurate biochemical score to correlate with the percentage of lipid content of the liver, determined by MR spectroscopy.