Metabolic adaptations in severe obesity: Insights from circulating oxylipins before and after weight loss

BACKGROUND

The relationship between lipid mediators and severe obesity remains unclear. Our study investigates the impact of severe obesity on plasma concentrations of oxylipins and fatty acids and explores the consequences of weight loss.

METHODS

In the clinical trial identifier NCT05554224 study, 116 patients with severe obesity and 63 overweight/obese healthy controls matched for age and sex (≈2:1) provided plasma. To assess the effect of surgically induced weight loss, we requested paired plasma samples from 44 patients undergoing laparoscopic sleeve gastrectomy one year after the procedure. Oxylipins were measured using ultra-high-pressure liquid chromatography coupled to a triple quadrupole mass spectrometer via semi-targeted lipidomics. Cytokines and markers of interorgan crosstalk were measured using enzyme-linked immunosorbent assays.

RESULTS

We observed significantly elevated levels of circulating fatty acids and oxylipins in patients with severe obesity compared to their metabolically healthier overweight/obese counterparts. Our findings indicated that sex and liver disease were not confounding factors, but we observed weak correlations in plasma with circulating adipokines, suggesting the influence of adipose tissue. Importantly, while weight loss restored the balance in circulating fatty acids, it did not fully normalize the oxylipin profile. Before surgery, oxylipins derived from lipoxygenase activity, such as 12-HETE, 11-HDoHE, 14-HDoHE, and 12-HEPE, were predominant. However, one year following laparoscopic sleeve gastrectomy, we observed a complex shift in the oxylipin profile, favoring species from the cyclooxygenase pathway, particularly proinflammatory prostanoids like TXB2, PGE2, PGD2, and 12-HHTrE. This transformation appears to be linked to a reduction in adiposity, underscoring the role of lipid turnover in the development of metabolic disorders associated with severe obesity.

CONCLUSIONS

Despite the reduction in fatty acid levels associated with weight loss, the oxylipin profile shifts towards a predominance of more proinflammatory species. These observations underscore the significance of seeking mechanistic approaches to address severe obesity and emphasize the importance of closely monitoring the metabolic adaptations after weight loss.

The Role of Olfactomedin 2 in the Adipose Tissue–Liver Axis and Its Implication in Obesity-Associated Nonalcoholic Fatty Liver Disease

This study’s objective was to assess the involvement of olfactomedin 2 (OLFM2), a secreted glycoprotein related to lipid metabolism regulation, in nonalcoholic fatty liver disease (NAFLD) mediated by the adipose-tissue–liver axis. OLFM2 mRNA expression was analyzed in subcutaneous (SAT) and visceral (VAT) adipose tissue by RT–qPCR. The cohort included women with normal weight (n = 16) or morbid obesity (MO, n = 60) who were subclassified into normal liver (n = 20), simple steatosis (n = 21), and nonalcoholic steatohepatitis (NASH, n = 19) groups. The results showed that OLFM2 expression in SAT was enhanced in MO individuals and in the presence of NAFLD. Specifically, OLFM2 expression in SAT was increased in mild and moderate degrees of steatosis in comparison to the absence of it. Moreover, OLFM2 expression in SAT was negatively correlated with interleukin-6 levels. On the other hand, OLFM2 expression in VAT decreased in the presence of NASH and exhibited a positive correlation with adiponectin levels. In conclusion, OLFM2 in SAT seems to be implicated in hepatic lipid accumulation. Additionally, since we previously suggested the possible implication of hepatic OLFM2 in NAFLD progression, now we propose a possible interaction between the liver and SAT, reinforcing the potential implication of this tissue in NAFLD development.

Increased Hepatic ATG7 mRNA and ATG7 Protein Expression in Nonalcoholic Steatohepatitis Associated with Obesity

The autophagy gene ATG7 has been shown to be essential for the induction of autophagy, a process that used to be suppressed in nonalcoholic fatty liver disease (NAFLD). However, the specific role of ATG7 in NAFLD remains unclear. The aim of this study was to analyze hepatic ATG7 mRNA and ATG7 protein expression regarding obesity-associated NAFLD. Patients included women classified into normal weight (NW, n = 6) and morbid obesity (MO, n = 72). The second group was subclassified into normal liver (NL, n = 11), simple steatosis (SS, n= 29), and nonalcoholic steatohepatitis (NASH, n = 32). mRNA expression was analyzed by RT-qPCR and protein expression was evaluated by Western blotting. Our results showed that NASH patients presented higher ATG7 mRNA and ATG7 protein levels. ATG7 mRNA expression was increased in NASH compared with SS, while ATG7 protein abundance was enhanced in NASH compared with NL. ATG7 mRNA correlated negatively with the expression of some hepatic lipid metabolism-related genes and positively with endocannabinoid receptors, adiponectin hepatic expression, and omentin levels. These results suggest that ATG7-mediated autophagy may play an important role in the pathogenesis of NAFLD, especially in NASH, perhaps playing a possible protective role. However, this is a preliminary study that needs to be further studied.

Increased Secreted Frizzled-Related Protein 5 mRNA Expression in the Adipose Tissue of Women with Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5) is an anti-inflammatory adipocytokine secreted by adipocytes that seems to be linked with nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the role of the SFRP5-wingless-MMTV integration site family member 5a (WNT5A) pathway, closely related to adipogenesis, in subcutaneous (SAT) and visceral adipose tissues (VAT) and its relationship with obesity-related NAFLD. Our cohort was composed of 60 women with morbid obesity (MO), who underwent hypocaloric diet, subclassified according to their hepatic histopathology and 15 women with normal weight. We observed increased SFRP5 mRNA expression in VAT and lower WNT5A expression in SAT in MO compared to normal weight. We found elevated SFRP5 expression in nonalcoholic steatohepatitis (NASH) in SAT and in mild simple steatosis (SS) and NASH in VAT. We observed higher WNT5A expression in SS compared to normal liver in SAT, and a peak of WNT5A expression in mild SS. To conclude, we reported increased SFRP5 mRNA expression in SAT and VAT of NAFLD-related to obesity subjects, suggesting an implication of the SFRP5-WNT5A pathway in NAFLD pathogenesis, probably due to the adipose tissue-liver axis. Since the mechanisms by which this potential interaction takes place remain elusive, more research in this field is needed.

Nonalcoholic Steatohepatitis Modifies Serum Iron-Related Variables in Patients with Morbid Obesity

Nonalcoholic steatohepatitis (NASH) is frequently associated with severe obesity. The liver is the principal storage repository for iron, and the excessive accumulation of this metal may promote hepatic inflammation. Laparoscopic sleeve gastrectomy (LSG) results in weight loss and improvement in comorbidities such as NASH. The aim of this study was to assess the specific NASH-related changes in iron metabolism and to investigate whether these changes are reversed by LSG. We included 150 patients with morbid obesity who provided 12-h fasting blood samples immediately before LSG together with an intraoperative wedge-liver biopsy. Thirty-eight patients with NASH underwent a second blood extraction 12 months postsurgery. Serum samples were collected from a control group comprising 50 healthy volunteers. We found significantly higher serum iron and transferrin concentrations in patients with NASH along with the highest degrees of steatosis, fibrosis, hepatocellular ballooning, and lobular inflammation. However, we did not find any significant accumulation of iron in the hepatic biopsies. Presurgery serum iron concentrations were lower in the patient group than in the control group and increased 1 year postsurgery. Serum ferritin levels showed changes in the opposite direction. We did not observe any significant change in serum transferrin concentrations. These changes were reversed by LSG. We conclude that alterations in serum iron-related variables are related to the severity of NASH in patients with morbid obesity, and these alterations are reversed by LSG. We also found that severe forms of NASH can be found in the absence of increased iron stores.

Deregulation of Secreted Frizzled-Related Protein 5 in Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5), an antagonist of the noncanonical WNT pathway, has a controversial role in liver disease. The aim of this study was to analyze the role of SFRP5 and the noncanonical WNT pathway in nonalcoholic fatty liver disease (NAFLD). Plasma SFRP5 levels were determined by ELISA in women with normal weight (NW; n = 20) and morbid obesity (MO; n = 69). Women with MO were subclassified according to hepatic histology into normal liver (NL; n = 28), NAFLD (n = 41) (simple steatosis (SS; n = 24), and nonalcoholic steatohepatitis (NASH; n = 17)). We used RT-qPCR to evaluate the hepatic mRNA expression of SFRP5, WNT5A, and JNK in women with MO. SFRP5 levels were lower in NW than in MO patients who underwent a very low-calorie diet before surgery. Hepatic SFRP5 mRNA expression was higher in SS than in NL or NASH; additionally, patients with hepatic inflammation or ballooning presented lower SFRP5 abundance. WNT5A and JNK expression was enhanced in NAFLD compared with NL. In conclusion, circulating SFRP5 levels depend on the diet, and hepatic SFRP5 seems to have a protective role in the first steps of NAFLD; however, SFRP5 could be deregulated in an advanced stage while WNT5A and JNK are activated, promoting liver damage.

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.

Glutaminolysis-induced mTORC1 activation drives non-alcoholic steatohepatitis progression

BACKGROUND & AIMS

A holistic insight on the relationship between obesity and metabolic dysfunction-associated fatty liver disease is an unmet clinical need. Omics investigations can be used to investigate the multifaceted role of altered mitochondrial pathways to promote nonalcoholic steatohepatitis, a major risk factor for liver disease-associated death. There are no specific treatments but remission via surgery might offer an opportunity to examine the signaling processes that govern the complex spectrum of chronic liver diseases observed in extreme obesity. We aim to assess the emerging relationship between metabolism, methylation and liver disease.

METHODS

We tailed the flow of information, before and after steatohepatitis remission, from biochemical, histological, and multi-omics analyses in liver biopsies from patients with extreme obesity and successful bariatric surgery. Functional studies were performed in HepG2 cells and primary hepatocytes.

RESULTS

The reversal of hepatic mitochondrial dysfunction and the control of oxidative stress and inflammatory responses revealed the regulatory role of mitogen-activated protein kinases. The reversible metabolic rearrangements leading to steatohepatitis increased the glutaminolysis-induced production of α-ketoglutarate and the hyperactivation of mammalian target of rapamycin complex 1. These changes were crucial for the adenosine monophosphate-activated protein kinase/mammalian target of rapamycin-driven pathways that modulated hepatocyte survival by coordinating apoptosis and autophagy. The signaling activity of α-ketoglutarate and the associated metabolites also affected methylation-related epigenomic remodeling enzymes. Integrative analysis of hepatic transcriptome signatures and differentially methylated genomic regions distinguished patients with and without steatohepatitis.

CONCLUSION

We provide evidence supporting the multifaceted potential of the increased glutaminolysis-induced α-ketoglutarate production and the mammalian target of rapamycin complex 1 dysregulation as a conceivable source of the inefficient adaptive responses leading to steatohepatitis.

LAY SUMMARY

Steatohepatitis is a frequent and threatening complication of extreme obesity without specific treatment. Omics technologies can be used to identify therapeutic targets. We highlight increased glutaminolysis-induced α-ketoglutarate production as a potential source of signals promoting and exacerbating steatohepatitis.

Laparoscopic sleeve gastrectomy alters 1H-NMR-measured lipoprotein and glycoprotein profile in patients with severe obesity and nonalcoholic fatty liver disease

Patients with morbid obesity frequently present non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) associated with pro-atherogenic alterations. Laparoscopic sleeve gastrectomy (LSG) is an effective treatment for weight reduction, and for the remission of hepatic alterations. Using ¹H-nuclear magnetic resonance (¹H-NMR), we investigated the effects of LSG on lipoprotein and glycoprotein profile in patients with morbid obesity and liver disease. We included 154 patients with morbid obesity (49 non-NASH, 54 uncertain NASH, 51 definite NASH). A blood sample was obtained before surgery and, in patients with definite NASH, one year after surgery. Patients with NASH had increased concentrations of medium and small VLDL particles, VLDL and IDL cholesterol concentrations, IDL, LDL, and HDL triglyceride concentrations, and elevated glycoprotein levels. These changes were more marked in patients with type 2 diabetes mellitus. LSG produced significant decreases in the concentration of VLDL particles, VLDL cholesterol and triglycerides, an increase in the concentration LDL particles and LDL cholesterol concentrations, and a decrease in protein glycation. We conclude that patients with obesity and NASH had significant alterations in circulating levels of lipoproteins and glycoproteins that were associated with the severity of the disease. Most of these changes were reversed post-LSG.

Insights into the treatment of postsleeve gastrectomy leak: analysis of the results of 105 cases on a national register

BACKGROUND

Many options have been put forward to treat staple line leaks after sleeve gastrectomy (SG) but no clear consensus has emerged concerning a management algorithm.

OBJECTIVES

Aiming to establish a pattern to tailor treatment, the Spanish Society of Obesity Surgery (SECO) and the Obesity Section of the Spanish Association of Surgeons (AEC) set up a national register to record treatment of leaks after SG.

SETTING

Multiple hospital centers, Spain.

METHODS

Between September 2016 and December 2017, cases were entered into an online database. Results were assessed according to the number and type of therapeutic procedures.

RESULTS

One hundred and five patients from 27 centers were diagnosed with postSG leak. The mean age was 44 years, and 77 (73%) were women. Mean body mass index (BMI) was 47 kg/m². Mortality was 7%. The first treatment was effective in 50% of cases with no significant differences between nonoperative management and surgery. We found no significant correlations between appearance of leak, type of treatment (nonoperative management or surgery), and treatment effectiveness. An endoscopic stent was the first nonoperative option in 30% of cases and second option in 50% of cases, with effectiveness of 61% and 50%, respectively. In patients requiring a third treatment option (n = 25), surgery was more effective than nonoperative treatment (75% versus 8%) and the incidence of complications secondary to endoscopic stent placement was high (71%).

CONCLUSION

The choice of postSG leak treatment depends on the patient's clinical condition and the site of the leak. Healing may be slow (>2 months) and may require several interventions using different approaches such as nonoperative treatment, endoscopic stents, or surgery. The effectiveness of endoscopic options decreases and the effectiveness of complex resective or derivative surgery increases with leak duration and the number of treatments required.

Hepatocyte Notch Signaling Deregulation Related to Lipid Metabolism in Women with Obesity and Nonalcoholic Fatty Liver

OBJECTIVE

This cohort study aimed to explore the relationship between the Notch signaling pathway and the degree of nonalcoholic fatty liver disease (NAFLD). Moreover, this study intended to investigate whether this pathway is related to hepatic lipid metabolism and Toll-like receptors (TLRs).

METHODS

This study used real-time polymerase chain reaction analysis to evaluate the hepatic expression level of all genes studied (Notch receptors NOTCH1, NOTCH2, NOTCH3, and NOTCH4, transcription factors HES1 and HES5, and Hes-related repressor proteins HEY1 and HEY2) in hepatic tissue from two cohorts: women with severe obesity (n = 57) and normal liver structure (n = 20) or NAFLD (n = 37).

RESULTS

In women with severe obesity and NAFLD, this study found downregulation of hepatic HES5 expression. This expression correlated positively with the hepatic expression of HES1, HEY1, and NOTCH3. This study also found a positive correlation between HES5 expression and sterol regulatory element-binding protein 1c (SREBP1c) and between NOTCH3 and several genes related to hepatic lipid metabolism (encoding liver X nuclear receptor α variant 1, farnesoid X nuclear receptor, SREBP1c, acetyl-CoA carboxylase 1, fatty acid synthase, peroxisome proliferator-activated receptor α, carnitine palmitoyltransferase 1, carnitine O-octanoyltransferase, ATP-binding cassette subfamily A member 1, and ATP-binding cassette subfamily G member 1). Finally, this study found a positive correlation between NOTCH2 and TLR2, TLR4, and TLR9 and a positive relationship between NOTCH1 and TLR9.

CONCLUSIONS

Taken together, these findings suggest that hepatic expression of Notch proteins and ligands in relation to lipid metabolism pathways in the liver could have a role in NAFLD pathogenesis.

Relationship between IL-8 Circulating Levels and TLR2 Hepatic Expression in Women with Morbid Obesity and Nonalcoholic Steatohepatitis

The progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) is linked to systemic inflammation. Currently, two of the aspects that need further investigation are diagnosis and treatment of NASH. In this sense, the aim of this study was to assess the relationship between circulating levels of cytokines, hepatic expression of toll-like receptors (TLRs), and degrees of NAFLD, and to investigate whether these levels could serve as noninvasive biomarkers of NASH. The present study assessed plasma levels of cytokines in 29 normal-weight women and 82 women with morbid obesity (MO) (subclassified: normal liver (n = 29), simple steatosis (n = 32), and NASH (n = 21)). We used enzyme-linked immunosorbent assays (ELISAs) to quantify cytokine and TLR4 levels and RTqPCR to assess TLRs hepatic expression. IL-1β, IL-8, IL-10, TNF-α, tPAI-1, and MCP-1 levels were increased, and adiponectin levels were decreased in women with MO. IL-8 was significantly higher in MO with NASH than in NL. To sum up, high levels of IL-8 were associated with the diagnosis of NASH in a cohort of women with morbid obesity. Moreover, a positive correlation between TLR2 hepatic expression and IL-8 circulating levels was found.

Plasma metabolic alterations in patients with severe obesity and non-alcoholic steatohepatitis

BACKGROUND

Obesity can influence hepatic mitochondrial function, and cause non-alcoholic steatohepatitis (NASH). Diagnosis and follow-up rely on invasive liver biopsy so blood-based markers are urgently required.

AIM

To investigate whether values of circulating metabolites from energy and one-carbon (1-C) metabolism may: (a) reflect hepatic mitochondrial flexibility failure and (b) act as NASH biomarkers.

METHODS

Patients with severe obesity undergoing bariatric surgery (n = 270) were investigated using quantitative targeted plasma metabolomics. Comparisons were with non-obese controls without liver disease (n = 50). Obese patients with NASH (n = 53) and without NASH (n = 130) representing extreme groups of liver disease were assessed to test the diagnostic ability of the measured circulating metabolites. Paired liver biopsy and plasma samples from NASH patients were available 1 year post-surgery and were evaluated to monitor metabolomic changes with liver damage resolution.

RESULTS

We identified correlations between human liver metabolism and obesity. High-plasma α-ketoglutarate (α-KG) and lactate concentrations in NASH patients indicating citric acid cycle replenishment via glutaminolysis might also be a crucial point in NASH onset. Plasma measurements of α-KG, β-hydroxybutyrate, pyruvate and oxaloacetate reduced the uncertainty in clinical diagnosis of NASH [area under receiver operating characteristic curve (AUC) of 0.826] and predicted NASH resolution without ambiguity (AUC of 0.999).

CONCLUSION

Changes in plasma mitochondrial metabolites appear to be associated with NASH. These metabolic responses may be dynamically remodelled following resolution of liver damage through massive weight loss.

Quantitative and Topographic Analysis by Immunohistochemical Expression of Ghrelin Gastric Cells in Patients with Morbid Obesity

PURPOSE

The cellular distribution of ghrelin positive cells is not well defined. The aim of the study is to quantify and determine the distribution of ghrelin cells in gastric mucosa in patients with morbid obesity and relate this finding to gender, comorbidities, gastritis, and plasmatic levels of acyl and desacylghrelin before and after laparoscopic sleeve gastrectomy.

PATIENT AND METHODS

We performed a study on 61 patients with BMI≥50 kg/m² operated by laparoscopic sleeve gastrectomy. Three gastric regions were analyzed by histopathology and immunohistology. Blood sample was taken before surgery, and at 6 and 12 months post-surgery, to study the plasma levels of ghrelin isoforms.

RESULTS

Ghrelin cells are present in all regions of the gastric mucosa, with a greater number in the body and the fundus. Difference was found in the antrum between male and female patients (p=0.018). Patients with arterial hypertension also showed a lower level of cells in antrum (p<0.05). Acylghrelin levels after surgery were significantly lower (32.83+5.6 pg/mL to 10.09+11.8 pg/mL, p<0.05). Values of desacylghrelin tended to decrease but no significant variation was observed (207.4+39.3 pg/mL to 188.84+52.3 pg/mL).

CONCLUSION

Our patients show ghrelin cells in all areas of the stomach. Gender, comorbidities, and gastritis are determinant on gastric ghrelin-producing cells distribution.

Laparoscopic sleeve gastrectomy reverses non-alcoholic fatty liver disease modulating oxidative stress and inflammation

BACKGROUND & AIMS

Hepatic alterations, such as in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are frequently associated with obesity. To investigate the molecular mechanisms of these alterations and to identify molecules that could be used as potential therapeutic targets, we investigated the modulation of hepatic indices of oxidative stress and inflammation in obese patients undergoing laparoscopic sleeve gastrectomy (LSG).

METHODS

Patients (n = 436) attending our obesity clinic underwent LSG for weight loss. We obtained a diagnostic intraoperative liver biopsy, and a sub-cohort (n = 120) agreed to a 1-year follow-up that included donation of blood samples and additional liver biopsies. Selected key molecules in blood and liver tissue were used to investigate the hepatic alterations in obesity, and their response to LSG.

RESULTS

One year post-surgery, the prevalence of diabetes, dyslipidemia and hypertension decreased significantly. LSG improved liver histology features in all patients. Improvement was greater in severe cases of NAFLD including those with steatohepatitis, bridging fibrosis or cirrhosis. Significant pre-surgery differences in plasma, and liver markers of oxidative stress and inflammation (including chemokine C-C motif ligand 2, paraoxonase-1, galectin-3, and sonic hedgehog) were observed between patients with, and those without, NASH; post-surgery indicated consistent improvements in these parameters.

CONCLUSION

Our study shows that the histology and liver function of patients with morbid obesity are significantly improved after LSG via mechanisms that involve the reduction of oxidative stress and inflammatory processes. These data encourage the use of LSG as a therapeutic option to improve, or resolve, NAFLD.

Circulating microbiota-derived metabolites: a "liquid biopsy?

BACKGROUND/OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) causes a wide spectrum of liver damage, from simple steatosis (SS) to cirrhosis. SS and non-alcoholic steatohepatitis (NASH) cannot be distinguished by clinical or laboratory features. Dysregulation of the gut microbiota is involved in NASH pathogenesis. The aim of this study was to assess the relationship between microbiota-derived metabolites and the degrees of NAFLD; also, to investigate whether these metabolites could be included in a panel of NASH biomarkers.

SUBJECTS/METHODS

We used liquid chromatography coupled to triple-quadrupole-mass spectrometry (LC-QqQ) analysis to quantify choline and its derivatives, betaine, endogenous ethanol, bile acids, short-chain fatty acids and soluble TLR4 in serum from women with normal weight (n = 29) and women with morbid obesity (MO) (n = 82) with or without NAFLD. We used real-time polymerase chain reaction (RT-PCR) analysis to evaluate the hepatic and intestinal expression level of all genes studied (TLR2, TLR4, TLR9, LXRα, SREBP1C, ACC1, FAS, PPARα, CPT1α, CROT, SREBP2, ABCA1, ABCG1 and FXR in the liver; TLR2, TLR4, TLR5, TLR9, GLP-1R, DPP-4, FXR and PPARɣ in the jejunum) in 82 women with MO with normal liver histology (NL, n = 29), SS (n = 32), and NASH (n = 21).

RESULTS

Hepatic FAS, TLR2, and TLR4 expression were overexpressed in NAFLD patients. TLR2 was overexpressed in NASH patients. In women with MO with NAFLD, we found upregulation of intestinal TLR9 expression and downregulation of intestinal FXR expression in women with NASH. Circulating TMAO, glycocholic acid and deoxycholic acid levels were significantly increased in NAFLD patients. Endogenous circulating ethanol levels were increased in NASH patients in comparison to those in SS patients.

CONCLUSIONS

These findings suggest that the intestine participates in the progression of NAFLD. Moreover, levels of certain circulating microbiota-related metabolites are associated with NAFLD severity and could be used as a "liquid biopsy" in the noninvasive diagnosis of NASH.

Low Circulating Levels of Neurotensin in Women with Nonalcoholic Fatty Liver Disease Associated with Severe Obesity

OBJECTIVE

This study was performed to investigate neurotensin plasma levels in patients with nonalcoholic fatty liver disease (NAFLD) associated with severe obesity.

METHODS

The plasma levels of neurotensin in 20 women with normal weight and 51 women with morbid obesity (MO) were measured, and women were subclassified according to their hepatic histology as having MO without NAFLD (n = 18) or MO with NAFLD (n = 33). The NAFLD group included 15 women with simple steatosis (SS) and 18 women with nonalcoholic steatohepatitis (NASH). To quantify neurotensin in plasma, a multiplex sandwich immunoassay with a Luminex magnetic bead-based platform was used.

RESULTS

Neurotensin levels were significantly decreased (P = 0.001) in women with MO and NAFLD (3.62 ± 0.85 ng/mL), compared with women with MO and normal liver function (11.65 ± 1.95 ng/mL; P = 0.001) and women with normal weight (13.68 ± 2.58 ng/mL; P = 0.001). There was no difference in levels between women with SS and women with NASH (P = 0.415).

CONCLUSIONS

Circulating levels of neurotensin were decreased in women with NAFLD associated with MO.

Hepcidin in morbidly obese women with non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in Western countries. Both iron and lipid metabolism seem to be involved in its pathogenesis. We aimed to assess the relationship between levels of hepcidin, the master iron-regulatory protein, in plasma and the presence of NAFLD in morbidly obese (MO) patients, and to investigate the association between the hepatic expression of the main iron and lipid metabolism -related genes.

Materials and methods

Enzyme-linked immunosorbent assay was used to measure plasma hepcidin levels in 49 normal-weight control women, 23 MO women with normal liver (NL) histology and 46 MO women with NAFLD. The mRNA expression of hepcidin, the main iron metabolism-related genes, and the main lipid-metabolism genes was quantified by qRT-PCR in liver biopsies from members of the MO group undergoing bariatric surgery.

Results

Circulating hepcidin levels were significantly greater in MO than in normal-weight control women. However, there were no significant differences between MO women with NL and those with NAFLD. PCR analysis showed increased expression of hepcidin, FPN1, TfR1 and TfR2 in the liver of MO NAFLD women compared to those with NL. Moreover, a positive association of hepatic hepcidin mRNA expression and the iron metabolism-related genes was found with some key genes involved in the lipid metabolism.

Conclusion

These findings suggest that circulating hepcidin levels are associated with obesity but not with the presence of NAFLD. However, the hepatic expression of hepcidin and the iron metabolism-related genes seem to play a role in regulating lipid metabolism pathways in liver, which has implications for NAFLD pathogenesis.

Increased Circulating Levels of Alpha-Ketoglutarate in Morbidly Obese Women with Non-Alcoholic Fatty Liver Disease

Background

Non-alcoholic fatty liver disease (NAFLD) causes a wide spectrum of liver damage, ranging from simple steatosis to cirrhosis. However, simple steatosis (SS) and steatohepatitis (NASH) cannot yet be distinguished by clinical or laboratory features. The aim of this study was to assess the relationship between alpha-ketoglutarate and the degrees of NAFLD in morbidly obese patients.

Materials and Methods

We used a gas chromatography-quadruple time-of-flight-mass spectrometry analysis to quantify alpha-ketoglutarate in serum from normal-weight subjects (n = 30) and morbidly obese women (n = 97) with or without NAFLD.

Results

We found that serum levels of alpha-ketoglutarate were significantly higher in morbidly obese women than in normal-weight women. We showed that circulating levels of alpha-ketoglutarate were lower in lean controls and morbidly obese patients without NAFLD. We also found that alpha-ketoglutarate serum levels were higher in both SS and NASH than in normal liver of morbidly obese patients. However, there was no difference between SS and NASH. Moreover, we observed that circulating levels of alpha-ketoglutarate were associated with glucose metabolism parameters, lipid profile, hepatic enzymes and steatosis degree. In addition, diagnostic performance of alpha-ketoglutarate has been analyzed in NAFLD patients. The AUROC curves from patients with liver steatosis exhibited an acceptable clinical utility. Finally, we showed that the combination of biomarkers (AST, ALT and alpha-ketoglutarate) had the highest accuracy in diagnosing liver steatosis.

Conclusion

These findings suggest that alpha-ketoglutarate can determine the presence of non-alcoholic fatty liver in morbidly obese patients but it is not valid a biomarker for NASH.

PNPLA3 Expression Is Related to Liver Steatosis in Morbidly Obese Women with Non-Alcoholic Fatty Liver Disease

Recent reports suggest a role for the Patatin-like phospholipase domain-containing protein 3 (PNPLA3) in the pathology of non-alcoholic fatty liver disease (NAFLD). Lipid deposition in the liver seems to be a critical process in the pathogenesis of NAFLD. The aim of the present work was to evaluate the association between the liver PNPLA3 expression, key genes of lipid metabolism, and the presence of NAFLD in morbidly obese women. We used real-time polymerase chain reaction (PCR) analysis to analyze the hepatic expression of PNPLA3 and lipid metabolism-related genes in 55 morbidly obese subjects with normal liver histology (NL, n = 18), simple steatosis (SS, n = 20), and non-alcoholic steatohepatitis (NASH, n = 17). Liver biopsies were collected during bariatric surgery. We observed that liver PNPLA3 expression was increased in NAFLD than in NL. It was also upregulated in SS than in NL. Interestingly, we found that the expression of PNPLA3 was significantly higher in severe than mild SS group. In addition, the expression of the transcription factors LXRα, PPARα, and SREBP2 was positively correlated with PNPLA3 liver expression. Regarding rs738409 polymorphism, GG genotype was positive correlated with the presence of NASH. In conclusion, our results show that PNPLA3 could be related to lipid accumulation in liver, mainly in the development and progression of simple steatosis.

Altered fatty acid metabolism-related gene expression in liver from morbidly obese women with non-alcoholic fatty liver disease

Lipid accumulation in the human liver seems to be a crucial mechanism in the pathogenesis and the progression of non-alcoholic fatty liver disease (NAFLD). We aimed to evaluate gene expression of different fatty acid (FA) metabolism-related genes in morbidly obese (MO) women with NAFLD. Liver expression of key genes related to de novo FA synthesis (LXRα, SREBP1c, ACC1, FAS), FA uptake and transport (PPARγ, CD36, FABP4), FA oxidation (PPARα), and inflammation (IL6, TNFα, CRP, PPARδ) were assessed by RT-qPCR in 127 MO women with normal liver histology (NL, n = 13), simple steatosis (SS, n = 47) and non-alcoholic steatohepatitis (NASH, n = 67). Liver FAS mRNA expression was significantly higher in MO NAFLD women with both SS and NASH compared to those with NL (p = 0.003, p = 0.010, respectively). Hepatic IL6 and TNFα mRNA expression was higher in NASH than in SS subjects (p = 0.033, p = 0.050, respectively). Interestingly, LXRα, ACC1 and FAS expression had an inverse relation with the grade of steatosis. These results were confirmed by western blot analysis. In conclusion, our results indicate that lipogenesis seems to be downregulated in advanced stages of SS, suggesting that, in this type of extreme obesity, the deregulation of the lipogenic pathway might be associated with the severity of steatosis.

Tissue-specific DNA methylation profiles regulate liver-specific expression of the APOA1/C3/A4/A5 cluster and can be manipulated with demethylating agents on intestinal cells

OBJECTIVE

The tissue-specific expression profiles of genes within the APOA1/C3/A4/A5 cluster play an important role in lipid metabolism regulation. We hypothesize that the tissue-specific expression of the APOA1/C3/A4/A5 gene cluster will show an inverse pattern with DNA methylation, and that repression in non- or low-expressing tissue, such as the intestine, can be reversed using epigenetic drugs.

METHODS AND RESULTS

We analyzed DNA samples from different human adult tissues (liver, intestine, leukocytes, brain, kidney, pancreas, muscle and sperm) using the Infinium HumanMethyation450 BeadChip array. DNA methylation profiles in APOA1/C3/A4/A5 gene cluster were confirmed by bisulfite PCR and pyrosequencing. To determine whether the observed tissue-specific methylation was associated with the expression profile we exposed intestinal TC7/Caco-2 cells to the demethylating agent 5-Aza-2'-deoxycytidine and monitored intestinal APOA1/C3/A4/A5 transcript re-expression by RT-qPCR. The promoters of APOA1, APOC3 and APOA5 genes were less methylated in liver compared to other tissues, and APOA4 gene was highly methylated in most tissues and partially methylated in liver and intestine. In TC7/Caco-2 cells, 5-Aza-2'-deoxycytidine treatment induced a decrease between 37 and 24% in the methylation levels of APOA1/C3/A4/A5 genes and a concomitant re-expression mainly in APOA1, APOA4 and APOA5 genes ranging from 22 to 600%.

CONCLUSIONS

We have determined the methylation patterns of the APOA1/C3/A4/A5 cluster that may be directly involved in the transcriptional regulation of this cluster. DNA demethylation of intestinal cells increases the RNA levels especially of APOA1, APOA4 and APOA5 genes.

Downregulation of lipogenesis and fatty acid oxidation in the subcutaneous adipose tissue of morbidly obese women

OBJECTIVE

The aim of this study was to analyse the expression of crucial genes in fatty acid metabolism in visceral (VAT) and subcutaneous (SAT) adipose tissue samples from morbidly obese women.

METHODS

The VAT and SAT expression of key genes in 145 morbidly obese women (MO, BMI > 40 Kg/m(2) ) and 18 normal weight control women by RT-PCR and Western Blot was analyzed.

RESULTS

In SAT, the expression levels of the genes related to lipogenesis and fatty acid oxidation were significantly lower in MO than in controls. In VAT, most of the lipogenic genes studied had similar expression levels in MO and control cohort. Regarding inflammation, IL6 was significantly higher in MO in both tissues whereas TNFα mRNA expression was significantly higher only in VAT.

CONCLUSIONS

Our results indicate that in morbidly obese patients, lipogenesis and fatty acid oxidation are downregulated in SAT, whereas in VAT these pathways are almost unchanged. By contrast, inflammation is induced in both adipose tissues. It is hypothesized that, in this type of extreme obesity, SAT works to limit any further development of fat mass, decreasing the expression of lipogenic and FA oxidative genes whereas VAT depot might have lost this capability.

Clinical and adipocytokine changes after bariatric surgery in morbidly obese women

OBJECTIVE

Recent studies report the effect of bariatric surgery on glycaemia control and prevention of type-2-diabetes in obese patients. This study is about the pathophysiological mechanisms associated to these changes.

DESIGN AND METHODS

Circulating levels of receptors of tumor necrosis factor (TNF-RI, TNF-RII), visfatin, high molecular weight (HMW) adiponectin, and C reactive protein (CRP) in 30 morbidly obese women (body mass index, BMI>40 kg/m(2) ) and 60 normal-weight controls (BMI>25 kg/m(2) ) were analyzed. Morbidly obese were studied at three time-points: before surgery (baseline), and 6 and 12 months after.

RESULTS

After surgery, the levels of TNF-RI, TNF-RII, visfatin, and CRP were significantly lower than its baseline levels, whereas HMW adiponectin was higher. Fasting glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA2-IR) levels were markedly lower postoperatively. High density lipoproteins (HDL) moderately increased, and triglyceride levels had sharply decreased. The study of the predictive value of variables indicated that preoperative levels of TNF-RI and visfatin correlated positively with levels of glucose, insulin, glycosylated hemoglobin A1c, and HOMA2-IR postoperatively, whereas adiponectin levels correlated negatively. Baseline CRP levels negatively linked to HDL and TNF-RII positively to triglyceride.

CONCLUSIONS

The preoperative profile with high levels of proinflammatory adipocytokines is linked to smaller improvements in glucose homeostasis and lipid factors. The use of a range of biomarkers may predict the level of metabolic changes following bariatric surgery.

Plasma vitamin D and parathormone are associated with obesity and atherogenic dyslipidemia: a cross-sectional study

Background

Low concentrations of plasma vitamin D (25(OH)D) have been associated with the development of metabolic syndrome (MetS), obesity, diabetes and cardiovascular disease. The objective of this study was to quantify the associations between 25(OH)D and parathormone (PTH) plasma levels and obesity, the presence of MetS, diabetes or atherogenic dyslipidemia (AD) in a large sample of individuals with different degrees of adiposity.

Methods

Retrospective study of all patients who had attended the obesity clinics in a Spanish hospital between 2009 and 2011, and whose concentrations of PTH, 25(OH)D, calcium and alkaline phosphatase had been determined (n=316, 75.9% women). Individuals were categorized by degree of adiposity, presence of MetS, and other comorbidities.

Results

PTH increased but 25(OH)D and calcium decreased with increasing adiposity. The prevalence of 25(OH)D deficiency or insufficiency increased with obesity (<10% when BMI<45kg/m², and 26% when >50). The prevalence of hyperparathyroidism increased from 12% in non-obese to 47.5% in morbidly obese individuals with BMI>50 kg/m². Low plasma 25(OH)D and high PTH concentrations were associated with an increased risk of MetS and AD. These associations disappeared, except in the case of AD for 25(OH)D when adjusting for BMI. Regression analysis revealed that BMI and age or seasonality were independent predictors of PTH and 25(OH)D levels, respectively.

Conclusions

BMI was the variable most strongly associated with plasma 25(OH)D and PTH concentrations in our study. Low 25(OH)D and high PTH concentrations were not independently associated with an increased risk of MetS, or diabetes. Our data support a possible contribution of plasma 25(OH)D to the pathogenesis of hypertriglyceridemia and AD through inflammation.

Plasma visfatin levels and gene expression in morbidly obese women with associated fatty liver disease

OBJECTIVES

The few studies on the physiopathological role of visfatin in morbid obesity and the related metabolic diseases have led us to examine visfatin levels and its liver gene expression in morbidly obese women with non-alcoholic fatty liver disease (NAFLD).

DESIGN AND METHODS

We examined the circulating levels of visfatin by ELISA in serum samples from 95 morbidly obese women (MO) (BMI>40 kg/m(2)) who underwent bariatric surgery and 38 normal weight control women (BMI<25 kg/m(2)). We analysed visfatin liver and adipose tissue mRNA expression by RT-PCR. We evaluated the circulating levels and gene expression of adiponectin, resistin, RBP4, TNFα, IL6 and CRP.

RESULTS

Serum visfatin was significantly higher in MO compared with controls, and also in MO with NAFLD was significantly higher than MO with normal liver. We found that NAFLD diabetic patients presented similar serum visfatin levels than non-diabetic. Serum visfatin correlated with IL6 (r=0.496; p<0.001) and CRP levels (r=0.241; p=0.049). Liver visfatin expression was significantly higher in MO compared to controls and was also significantly higher in MO with NAFLD than in MO with normal liver. Visfatin liver expression correlated positively with resistin (r=0.436, p=0.018) and TNFα expression (r=0.328, p=0.028). Visfatin expression in adipose tissues was similar among the MO groups analysed.

CONCLUSION

Serum visfatin and its liver expression are higher in MO women with NAFLD, irrespective of the presence of diabetes. Serum visfatin and its liver expression correlate positively with pro-inflammatory factors. These findings suggest that visfatin may be a molecule related with fat inflammation in morbid obesity and fatty liver disease.

Repeated Aspergillus isolation in respiratory samples from non-immunocompromised patients not selected based on clinical diagnoses: colonisation or infection?

Background

Isolation of Aspergillus from lower respiratory samples is associated with colonisation in high percentage of cases, making it of unclear significance. This study explored factors associated with diagnosis (infection vs. colonisation), treatment (administration or not of antifungals) and prognosis (mortality) in non-transplant/non-neutropenic patients showing repeated isolation of Aspergillus from lower respiratory samples.

Methods

Records of adult patients (29 Spanish hospitals) presenting ≥2 respiratory cultures yielding Aspergillus were retrospectively reviewed and categorised as proven (histopathological confirmation) or probable aspergillosis (new respiratory signs/symptoms with suggestive chest imaging) or colonisation (symptoms not attributable to Aspergillus without dyspnoea exacerbation, bronchospasm or new infiltrates). Logistic regression models (step–wise) were performed using Aspergillosis (probable + proven), antifungal treatment and mortality as dependent variables. Significant (p < 0.001) models showing the highest R² were considered.

Results

A total of 245 patients were identified, 139 (56.7%) with Aspergillosis. Aspergillosis was associated (R² = 0.291) with ICU admission (OR = 2.82), congestive heart failure (OR = 2.39) and steroids pre-admission (OR = 2.19) as well as with cavitations in X-ray/CT scan (OR = 10.68), radiological worsening (OR = 5.22) and COPD exacerbations/need for O₂ interaction (OR = 3.52). Antifungals were administered to 79.1% patients with Aspergillosis (100% proven, 76.8% probable) and 29.2% colonised, with 69.5% patients receiving voriconazole alone or in combination. In colonised patients, administration of antifungals was associated with ICU admission at hospitalisation (OR = 12.38). In Aspergillosis patients its administration was positively associated (R² = 0.312) with bronchospasm (OR = 9.21) and days in ICU (OR = 1.82) and negatively with Gold III + IV (OR = 0.26), stroke (OR = 0.024) and quinolone treatment (OR = 0.29). Mortality was 78.6% in proven, 41.6% in probable and 12.3% in colonised patients, and was positively associated in Aspergillosis patients (R² = 0.290) with radiological worsening (OR = 3.04), APACHE-II (OR = 1.09) and number of antibiotics for treatment (OR = 1.51) and negatively with species other than A. fumigatus (OR = 0.14) and aspergillar tracheobronchitis (OR = 0.27).

Conclusions

Administration of antifungals was not always closely linked to the diagnostic categorisation (colonisation vs. Aspergillosis), being negatively associated with severe COPD (GOLD III + IV) and concomitant treatment with quinolones in patients with Aspergillosis, probably due to the similarity of signs/symptoms between this entity and pulmonary bacterial infections.

FABP 4 is associated with inflammatory markers and metabolic syndrome in morbidly obese women

OBJECTIVE

The adipocyte/macrophage fatty acid-binding protein 4 (FABP4) has been described as a biomarker for adiposity and metabolic syndrome (MS). The aims of this study were to assess the relationship between FABP4 and inflammatory cytokines related to obesity, and to evaluate FABP4 mRNA expression in visceral and subcutaneous adipose tissue in non-diabetic morbidly obese women versus healthy lean women.

METHODS

We analyzed circulating levels of FABP4 in 81 Spanish women: 38 lean (body mass index (BMI)<25 kg/m(2)) and 43 morbidly obese (BMI>40 kg/m(2)). We took 30 follow-up blood samples at 6 and 12 months after bariatric surgery. We assessed FABP4 gene expression in samples of subcutaneous abdominal and visceral adipose tissue. Adipose tissue mRNA expression was determined by real-time RT-PCR.

RESULTS

In morbidly obese women, plasma FABP4 levels were significantly higher than in non-obese patients. These levels positively correlated with BMI, homeostasis model assessment of insulin resistance (HOMA2-IR), and plasma glucose and insulin levels. Post-operative FABP4 levels decreased by a maximum of 30% after 12 months. We also found an inverse association between FABP4 and adiponectin levels, and positive correlations between FABP4 and circulating leptin, tumor necrosis factor (TNF) receptors, C-reactive protein (CRP) and interleukin 6 levels. Linear regression analysis revealed that FABP4 was more closely related to HOMA2-IR than adiponectin, CRP, TNF-RI, or leptin. Furthermore, high circulating FABP4 levels were associated with the presence of MS. FABP4 mRNA expression in visceral adipose tissue was related to its circulating levels in morbidly obese women.

CONCLUSIONS

Our results indicate that serum FABP4 is associated with inflammatory factors related to obesity and MS in non-diabetic morbidly obese women.

Parameters related to oxygen free radicals in human skin: a study comparing healthy epidermis and skin cancer tissue

In vitro studies with tumor cells have demonstrated that oxygen free radicals are involved in the development of skin cancers and that variations in the body's defense mechanisms can modify the course of the disease. To assess the validity of this hypothesis in spontaneous tumors, we determined glutathione S-transferase, superoxide dismutase, reduced and oxidized glutathione, and thiobarbituric acid reactive substances in healthy whole skin (n = 95), dermis (n = 73), and epidermis (n = 69). The values were compared with those obtained in three types of skin cancer: basal cell carcinoma (n = 16), squamous cell carcinoma (n = 6), and melanoma (n = 33). In healthy skin, glutathione S-transferase, superoxide dismutase, reduced glutathione, and oxidized glutathione were higher in epidermis than in dermis, whereas thiobarbituric acid reactive substances were higher in dermis than in epidermis; whole skin had intermediate values. These results suggest that there is an induction of some anti-oxygen free radicals mechanisms in epidermis as a result of increased oxygen free radicals production. Glutathione S-transferase and thiobarbituric acid reactive substances were higher in all types of tumor than in healthy epidermis but oxidized glutathione was lower. Reduced glutathione and superoxide dismutase activity were lower in basal cell carcinoma and squamous cell carcinoma samples. Glutathione S-transferase increased, whereas superoxide dismutase and thiobarbituric acid reactive substances decreased in melanoma samples in direct relation to the Clark levels. Higher glutathione S-transferase activity, particularly in the most invasive forms of melanoma, indicates that this type of cancer is more malignant. Similarly, a decrease in superoxide dismutase activity can also encourage progression of the tumor. These results are in accord with those from tumor cell cultures and could suggest new strategies (gene therapy) for managing skin cancer.

Tacrolimus rescue therapy for cyclosporine-induced nephrotoxicity

Following renal transplantation, the long-term use of cyclosporine can cause nephrotoxicity. This small study of ten patients looks at the effects of tacrolismus rescue therapy over a 6-month period. After conversion to tacrolismus, renal function improved in seven patients, progressive graft dysfunction slowed and almost stabilized in two patients, and, in the remaining patient, deterioration continued and hemodialysis treatment was initiated at the end of the study period. A greater number of patients and a longer follow up are necessary to confirm these initially impressive results.