Expression of energy metabolism related genes in the gastric tissue of obese individuals with non-alcoholic fatty liver disease.

BACKGROUND: Stomach is an integral part of the energy balance regulating circuit. Studies exploring the effects of cross-system changes in the energy homeostasis in stomach tissue are scarce. The proximity of the stomach to liver--the most common secondary target affected by obesity--suggests that these two organs are exposed to each other's local secretion. Therefore, we aimed at expression profiling of energy metabolism associated genes in the gastric tissue of obese non-alcoholic fatty liver disease (NAFLD) patients. METHODS: A total of 24 patients with histologically-proven NAFLD were included. In the gastric tissue, gene expression profiling of 84 energy metabolism associated genes was carried out. RESULTS: The accumulation of the fat in the liver parenchyma is accompanied by downregulation of genes encoding for carboxypeptidase E (CPE) and Interleukin 1B (IL1B) in the gastric mucosa of same patient. In patients with high grade hepatic steatosis, Interleukin 1 beta encoding gene with anorexigenic function, IL1B was downregulated. The levels expression of 21 genes, including ADRA2B, CNR1 and LEP were significantly altered in the gastric tissue of NAFLD patients with hepatic inflammation. There were also indications of an increase in the opioid signaling within gastric mucosa that may results in a shift to proinflammatory environment within this organ and contribute to systemic inflammation and the pathogenic processes in hepatic parenchyma. CONCLUSIONS: We have shown differential expression of energy metabolism associated genes in the gastric tissue of obese NAFLD patients. Importantly, these gene expression profiles are associated with changes in the hepatic parenchyma as reflected in increased scores for hepatic steatosis, inflammation, fibrosis and NASH. This study suggests the complex interplay of multiple organs in the pathogenesis of obesity-related complications such as NAFLD and provides further evidence supporting an important role for gastric tissue in promoting obesity-related complications.

Expression of genes for microRNA-processing enzymes is altered in advanced non-alcoholic fatty liver disease.

BACKGROUND AND AIM: Recently, microRNAs (miRNA) have been linked to the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and its progression to non-alcoholic steatohepatitis (NASH). First transcribed as pri-miRNA, these molecules are further processed by a complex of endonuclear and cytosolic RNA binding molecules to form mature miRNAs. The aim of this study is to investigate mechanisms of miRNA regulation in the visceral adipose of obese NAFLD patients via measuring expression of miRNA processing enzymes and pri-miRNA. METHODS: Total RNAs were extracted from visceral adipose tissue (VAT) samples collected from patients undergoing bariatric surgery. All patients had biopsy-proven NAFLD (NASH patients [n = 12] and non-NASH NAFLD [n = 12]). For each patient, we profiled mRNA levels for three miRNA processing elements (Drosha, DGCR8, and Dicer1) and seven pri-miRNAs (pri-miR-125b-2, pri-miR-16-2, pri-miR-26a-1, pri-miR-26a-2, pri-miR-7-1, pri-miR-7-2, and pri-miR-7-3). RESULTS: Expression of Dicer1, Drosha and DGCR8 was significantly increased within the NASH cohort along with expression of pri-miR-7-1. The presence of focal necrosis on the liver biopsy correlated significantly with levels of Dicer1 and DGRC8. Both NASH and ballooning degeneration of hepatocytes correlated negatively with the expression levels of hsa-miR-125b. Histologic NASH correlated positively with the expression levels of pri-miR-16-2 and pri-miR-7-1. The presence of the hepatocyte's ballooning degeneration in the liver biopsy correlated positively with pri-miR-26a-1 and pri-miR-7-1. The expression profile of pri-miR-125b-2 also correlated positively with body mass index. CONCLUSIONS: Our findings support the hypothesis that VAT-derived miRNA may contribute to the pathogenesis of NASH in obese patients.

Expression of inflammation-related genes is altered in gastric tissue of patients with advanced stages of NAFLD.

Obesity is associated with chronic low-grade inflammation perpetuated by visceral adipose. Other organs, particularly stomach and intestine, may also overproduce proinflammatory molecules. We examined the gene expression patterns in gastric tissue of morbidly obese patients with nonalcoholic fatty liver disease (NAFLD) and compared the changes in gene expression in different histological forms of NAFLD. Stomach tissue samples from 20 morbidly obese NAFLD patients who were undergoing sleeve gastrectomy were profiled using qPCR for 84 genes encoding inflammatory cytokines, chemokines, their receptors, and other components of inflammatory cascades. Interleukin 8 receptor-beta (IL8RB) gene overexpression in gastric tissue was correlated with the presence of hepatic steatosis, hepatic fibrosis, and histologic diagnosis of nonalcoholic steatohepatitis (NASH). Expression levels of soluble interleukin 1 receptor antagonist (IL1RN) were correlated with the presence of NASH and hepatic fibrosis. mRNA levels of interleukin 8 (IL8), chemokine (C-C motif) ligand 4 (CCL4), and its receptor chemokine (C-C motif) receptor type 5 (CCR5) showed a significant increase in patients with advanced hepatic inflammation and were correlated with the severity of the hepatic inflammation. The results of our study suggest that changes in expression patterns for inflammatory molecule encoding genes within gastric tissue may contribute to the pathogenesis of obesity-related NAFLD.

Performance of Noninvasive Liver Fibrosis Tests in Morbidly Obese Patients with Nonalcoholic Fatty Liver Disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is highly prevalent in morbidly obese patients, and fibrosis is an independent predictor of mortality. Noninvasive tests (NITs) are being developed for the detection of advanced fibrosis (AF). PURPOSE: To assess the performance of three NITs (NAFLD fibrosis score, NFS, fibrosis-4 index, FIB-4, and aspartate aminotransferase-to-platelet ratio, APRI), in the identification of AF among morbidly obese patients. MATERIALS AND METHODS: Patients, who underwent bariatric surgery between 2004 and 2009 and had liver biopsy, were included. Fibrosis stages ≥ F2 and ≥ F3 were defined as significant and AF, respectively. Published and optimal thresholds (Youden index) for NFS, FIB-4 and APRI, sensitivity, specificity, positive and negative predictive values (PPV-NPV), and area under the receiver operator curves (AUROC) were evaluated. RESULTS: Among 584 patients (mean age 43.3 ± 11.3 years, 21.2% male, 75% white, mean BMI 45.5 ± 8.80), 31.7% had NASH. Stages distributions were F1 = 68.1%, F2 = 16.4%, F3 = 8%, and F4 = 3.2%. At published thresholds, all 3 NITs performed poorly for detection of AF, with AUROC < 0.62. Overall performance at optimal thresholds improved to 0.68, 0.72, and 0.74 for NFS, FIB-4, and APRI, respectively. At optimal thresholds, all tests had good NPV (94.4-95.9%) but low PPV (24.2-32.5%). Combinations of the tests did not improve their performance. CONCLUSIONS: NFS, FIB-4, and APRI fall short to detect advanced fibrosis but valuable for excluding advanced fibrosis. More research is needed to develop new NITs with high positive predictive value.

Preoperative prediction of stomach weight to be removed in laparoscopic sleeve gastrectomy procedure.

Sleeve gastrectomy (SG) is a surgical procedure that includes a longitudinal lateral gastrectomy to reduce food intake by reducing the capacity of the stomach. The technique of SG as a primary procedure has evolved since it was first introduced in 2001. Some perform the SG over smaller bougie sizes (30-40 Fr) or an NG tube. Some begin the SG near the pylorus (2 cm) while others avoid the antral/pyloric area. Establishing the mass or volume of stomach remaining is subject to limitations associated with the in vivo status. However, quantifying the amount (mass) of stomach removed is definitively an objective measure. The study was conducted to determine the relationship between the amount of stomach excised and the patient's gender and preoperative weight and height. Data was collected prospectively and was compiled in a review of 165 (136 Female and 29 Male) patients who underwent laparoscopic SG from December 7, 2001 to March 18, 2004 by a single surgeon at three institutions using the same technique for performance and measurement. The empty weight and capacity of resected stomach specimens were measured intra-operatively and subsequently correlated with the patient's gender, preoperative weight, and height. The mean height of male patients was 179.7+/-7.1 (CM) and the mean height of female patients was 165.1+/-7.1(CM). The mean weight of stomach tissue removed from male patients was 160.3±29.4 (G) and from female patients was 123.5±40.4 (G). The difference in height and weight between men and women was statistically significant (P-value<0.0001). The empty stomach weight and capacity both are linearly related to each other (R-square=0.9292, P-value<.0001). There is evidence showing the statistically significant correlation among preoperative height, gender, and preoperative weight and amount of stomach removed. For the average height patient, removal of gastric tissue weighing less than 160 grams in males and 120 grams in females may indicate an inadequate resection. This removes a stomach capacity of approximately 1600 cc's and 1200 cc's respectively.

Expression of cytokine signaling genes in morbidly obese patients with non-alcoholic steatohepatitis and hepatic fibrosis.

BACKGROUND: White adipose tissue (WAT) from visceral adiposity plays an important role in the pathogenesis of non-alcoholic steatohepatitis (NASH). Development of NASH and its progression to fibrosis is partially due to cytokines and adipokines produced by WAT. The aim of this study was to assess the association of hepatic fibrosis and NASH by evaluating the intrinsic differences in the inflammatory cytokine signaling in the visceral adipose tissue obtained from morbidly obese patients. METHODS: We used targeted microarrays representing human genes involved in the inflammatory and fibrogenic reactions to profile visceral adipose samples of 15 well-matched NASH patients with and without fibrosis. Additionally, visceral adipose samples were subjected to real-time polymerase chain reaction profiling of 84 inflammations related genes. RESULTS: Eight genes (CCL2, CCL4, CCL18, CCR1, IL10RB, IL15RA, and LTB) were differentially expressed in NASH with fibrosis. Additionally, an overlapping but distinct list of the differentially expressed genes were found in NASH with type II diabetes (DM; IL8, BLR1, IL2RA, CD40LG, IL1RN, IL15RA, and CCL4) as compared to NASH without DM. CONCLUSIONS: Inflammatory cytokines are differentially expressed in the adipose tissue of NASH with fibrosis, as well in NASH with DM. These findings point at the interaction of adipose inflammatory cytokines, DM, hepatic fibrosis in NASH, and its progression to cirrhosis and end-stage liver disease.

Metabolic syndrome after laparoscopic bariatric surgery.

BACKGROUND: Metabolic syndrome (MS) is common among morbidly obese patients undergoing bariatric surgery. The aim of this study was to assess the impact and predictors of bariatric surgery on the resolution of MS. METHODS: Subjects included 286 patients [age 44.0 +/- 11.5, female 78.2%, BMI 48.7 +/- 9.4, waist circumference 139 +/- 20 cm, AST 23.5 +/- 14.9, ALT 30.0 +/- 20.1, type 2 diabetes mellitus (DM) 30.1% and MS 39.2%] who underwent bariatric surgery. RESULTS: Of the entire cohort, 27.3% underwent malabsorptive surgery, 55.9% underwent restrictive surgery, and 16.8% had combination restrictive-malabsorptive surgery. Mean weight loss was 33.7 +/- 20.1 kg after restrictive surgery (follow up period 298 +/- 271 days), 39.4 +/- 22.9 kg after malabsorptive surgery (follow-up period 306 +/- 290 days), and 28.3 +/- 14.1 kg after combination surgery (follow-up period 281 +/- 239 days). Regardless of the type of bariatric surgery, significant improvements were noted in MS (p values from <0.0001-0.01) as well as its components such as DM (p values from <0.0001-0.0005), waist circumference (p values <0.0001), BMI (p values <0.0001), fasting serum triglycerides (p values <0.0001 to 0.001), and fasting serum glucose (p values <0.0001). Additionally, a significant improvement in AST/ALT ratio (p value = 0.0002) was noted in those undergoing restrictive surgery. Multivariate analysis showed that patients who underwent malabsorptive bariatric procedures experienced a significantly greater percent excess weight loss than patients who underwent restrictive procedures (p value = 0.0451). Percent excess weight loss increased with longer postoperative follow-up (p value <0.0001). CONCLUSIONS: Weight loss after bariatric surgery is associated with a significant improvement in MS and other metabolic factors.

Apnoeic-hypopnoeic episodes during obstructive sleep apnoea are associated with histological nonalcoholic steatohepatitis.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) and obstructive sleep apnoea are associated with metabolic syndrome and atherosclerotic heart disease. This study evaluates the potential association between the NAFLD subtypes and a number of polysomnographical (PSG) parameters. METHODS: This study included patients undergoing bariatric surgery with extensive clinical and histological data for whom complete PSG data before surgery were also available. Excess alcohol intake and other causes of liver disease were excluded. Apnoea, hypopnoea and apnoea-hypopnoea index (AHI) were calculated as described previously. RESULTS: In this study, a total of 101 patients [77 nonalcoholic steatohepatitis (NASH) and 22 non-NASH controls] with PSG data were included (age 42.9 +/- 11.4 years, body mass index 51.6 +/- 9.5 kg/m(2), fasting serum glucose 117.4 +/- 53.4 mg/dl, fasting serum triglycerides 171.3 +/- 82.9 mg/dl, 58% hypertension and 33% diabetes mellitus). Subjects with histological NASH had significantly lower lowest desaturation (77 vs. 85%, P=0.006), lower mean nocturnal oxygen saturation (91 vs. 93%, P=0.05), higher AHI (35 vs. 22, P=0.03), higher respiratory disturbance index (46 vs. 21, P=0.02) and higher alanine aminotransferase/aspartate aminotransferase ratio (1.4 vs. 1.3, P=0.05) compared with non-NASH controls. In multivariate analysis, the lowest desaturation (P=0.04) was independently associated with histological NASH. Lowest desaturation and mean nocturnal oxygen saturation were significantly lower in subjects with fibrosis (76 vs. 85%, P=0.004 and 90.4 vs. 93.0%, P=0.02). CONCLUSIONS: Our results suggest that the frequent nocturnal hypoxic episodes in NAFLD patients may be a risk factor for developing NASH. Additional studies are needed to study the effect of optimizing sleep apnoea management on the outcomes of patients with NAFLD.

Gene expression patterns in hepatic tissue and visceral adipose tissue of patients with non-alcoholic fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) and its progressive form, non-alcoholic steatohepatitis (NASH), are among the least understood metabolic consequences of obesity. Increasingly, omental adipose tissue is recognized as a biologically active organ in the pathogenesis of NAFLD. Differences in transcriptional regulation in omental adipose tissue and liver tissue may provide important insights into the pathogenesis of NAFLD and its progression. METHODS: Transcriptional profiles were obtained for liver and visceral adipose specimens of morbidly obese patients undergoing bariatric surgery. Functional analyses with the Ingenuity Pathways Knowledge Base (IPKB) and IPA 4.0 software identified genes that potentially play hepatoprotective roles as well as those potentially involved in the pathogenesis of NASH. TNFalpha and IL6 were measured in the serum samples. RESULTS: Tissue from patients with NASH showed prominent adipose-specific deregulation of genes related to inflammation and the immune system. A number of liver and adipose-specific functional networks, including those centered at TNFalpha, JUN/JUNB, and IFNgamma were highlighted as related to the NASH pathogenesis. The results also showed compensatory increases in hepatic detoxification enzymes and decreases in the gene network controlled by transcription factor COUP-TFII. CONCLUSION: Our findings support the hypothesis that adipocyte secretion plays an important role in the development of NAFLD.

Gene expression of leptin, resistin, and adiponectin in the white adipose tissue of obese patients with non-alcoholic fatty liver disease and insulin resistance.

BACKGROUND: Adipose tissue is an active endocrine organ that secretes a variety of metabolically important substances including adipokines. These factors affect insulin sensitivity and may represent a link between obesity, insulin resistance, type 2 diabetes (DM), and nonalcoholic fatty liver disease (NAFLD). This study uses real-time polymerase chain reaction (PCR) quantification of mRNAs encoding adiponectin, leptin, and resistin on snap-frozen samples of intra-abdominal adipose tissue of morbidly obese patients undergoing bariatric surgery. METHODS: Morbidly obese patients undergoing bariatric surgery were studied. Patients were classified into two groups: Group A (with insulin resistance) (N=11; glucose 149.84 +/- 40.56 mg/dL; serum insulin 8.28 +/- 3.52 microU/mL), and Group B (without insulin resistance) (N=10; glucose 102.2 +/- 8.43 mg/dL; serum insulin 3.431 +/- 1.162 microU/mL). RESULTS: Adiponectin mRNA in intra-abdominal adipose tissue and serum adiponectin levels were significantly lower in Group A compared to Group B patients (P<0.016 and P<0.03, respectively). Although serum resistin was higher in Group A than in Group B patients (P<0.005), resistin gene expression was not different between the two groups. Finally, for leptin, neither serum level nor gene expression was different between the two groups. Serum adiponectin level was the only predictor of nonalcoholic steatohepatitis (NASH) in this study (P=0.024). CONCLUSIONS: Obese patients with insulin resistance have decreased serum adiponectin and increased serum resistin. Additionally, adiponectin gene expression is also decreased in the adipose tissue of these patients. This low level of adiponectin expression may predispose patients to the progressive form of NAFLD or NASH.

Laparoscopic transduodenal sphincteroplasty.

BACKGROUND: Common bile duct stones are a difficult problem, often leading to conversion to an open operation or repeated endoscopic procedures. Both strategies are associated with added morbidity. MATERIALS AND METHODS: A new technique was developed to perform a traditional sphincteroplasty using minimally invasive methods. The procedure was performed on two patients with distal common bile duct stones; each patient had previously undergone at least two unsuccessful preoperative endoscopic retrograde cholangiopancreatography procedures by at least two different experienced endoscopists. RESULTS: In both patients, a laparoscopic transduodenal sphincteroplasty was successfully completed. A transduodenal common bile duct exploration was performed at the time of sphincterotomy, successfully clearing the common bile duct in both cases. There were no untoward postoperative sequelae. Follow-up at one year was satisfactory in both patients. CONCLUSION: Laparoscopic transduodenal sphincteroplasty can be safely performed in patients with common bile duct stones refractory to endoscopic retrograde cholangiopancreatography. This technique offers a new approach to the management of common bile duct stones, and can spare patients the need for an open operation or subsequent endoscopic procedures.

Predictors of nonalcoholic steatohepatitis and advanced fibrosis in morbidly obese patients.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a common form of chronic liver disease in the United States. It is commonly associated with the components of the metabolic syndrome including obesity. From the spectrum of NAFLD, only patients with nonalcoholic steatohepatitis (NASH) have been convincingly shown to have a potential for progression to cirrhosis. We report the prevalence of NAFLD and NASH as well as predictors of NASH and advanced fibrosis in morbidly obese patients. METHODS: 212 consecutive patients who underwent bariatric surgery were enrolled in the study. A liver biopsy was performed at the time of the surgery. Causes of chronic liver disease other than NAFLD were excluded by clinical and laboratory evaluation. RESULTS: The prevalence of NAFLD was 93%. Of those with NAFLD, 26% had NASH. 17 patients (9%) had advanced fibrosis (i.e., bridging fibrosis or cirrhosis). Male gender, AST, and type 2 diabetes mellitus were independently associated with NASH. Waistto-hip ratio, AST, and focal hepatocyte necrosis on liver biopsy were independently associated with advanced fibrosis. Interestingly, while AST was associated with NASH and advanced fibrosis, the majority of the patients with either NASH or advanced fibrosis had normal AST. CONCLUSIONS: NAFLD and NASH are very common in morbidly obese patients undergoing bariatric surgery. Features associated with the metabolic syndrome and liver cell injury are independently associated with either NASH or advanced fibrosis.

Obesity-related differential gene expression in the visceral adipose tissue.

BACKGROUND: This study investigates the expression patterns in human adipose tissue, and identifies genes that may be involved in the abnormal energy homeostasis. METHODS: Subjects were prospectively recruited from morbidly obese patients undergoing bariatric surgery and from non-obese organ donors. Extensive clinical data and visceral fat specimens were obtained from each subject at the time of surgery. A group of 50 obese patients and 9 non-obese controls were selected for further study. Two custom two-color cDNA microarrays were produced with 40,173 human individual cDNA clones. Microarray experiments were performed for each sample, and a selected group of gene expression values were confirmed with real-time RT-PCR. RESULTS: A comparison of gene expression profiles from obese and non-obese patients identified 1,208 genes with statistically significant differential expression between the 2 groups. Most prominent among these genes are multiple glycolysis enzyme encoding genes; others are involved in oxysterol biosynthesis and signaling, or are ATP-binding transporters and solute carriers. CONCLUSION: Differential gene expression in the adipose tissue of morbidly obese patients includes genes related to lipid and glucose metabolism, membrane transport, and genes promoting the cell cycle. These findings are a first step toward clarifying the molecular pathogenesis of obesity and identifying potential targets for therapeutic intervention.

Tissue thickness of human stomach measured on excised gastric specimens from obese patients.

Laparoscopic linear cutting staplers are commonly used in bariatric surgery. Although many staple sizes are available, the clinical results of a staple line vary depending on the staple size and tissue environment. To help surgeons choose the proper staple size as well as establish design parameters for the development of new stapling devices, understanding the mechanical properties of the tissue is necessary. Knowing the distribution of the thickness of the stomach tissue would allow for increased accuracy in defining key design parameters for stapling devices, thus improving their performance in the operating theater. To this end, 50 sleeve/lateral gastrectomy specimens were obtained in a consecutive series from individuals undergoing weight loss surgery. Thickness measurements were performed at six predetermined sites. Results show that stomach thickness varies from thinnest at the proximal end near the esophageal junction to thickest near the pylorus. The data also suggest that the stomach is thinner along the greater curvature. Due to the variation in thickness of the stomach, laparoscopic linear cutting staplers with thicker staples are recommended when transecting the antrum. This thickness data will facilitate the development of devices with appropriate aperture closure for correct tissue compression.

Perioperative care of the patient with morbid obesity.

Obesity recently has been called an epidemic. In the United States, more than 60% of adults are overweight. Although obesity and morbid obesity share numerous etiological factors (eg, genetic, environmental, psychosocial, economic), accepted treatment options differ. Morbid obesity requires urgent and definitive correction to treat both current and possible future complications and to help prevent a probable shortened lifespan. Generally, it is accepted that nonsurgical approaches to weight loss for a person who is morbidly obese are unsuccessful. This Home Study describes the major surgical procedures currently available to treat morbid obesity and discusses the information that nurses need to know about perioperative care of patients who are morbidly obese.

Association of obestatin, ghrelin, and inflammatory cytokines in obese patients with non-alcoholic fatty liver disease.

BACKGROUND: Three protein products of ghrelin gene (acylated ghrelin, des-acylated ghrelin, and obestatin) are involved in appetite stimulation and suppression. Additionally, there is some evidence suggesting their involvement in metabolic and inflammatory pathways which may be implicated in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The aim of this study was to examine the relationships of ghrelin gene products in patients with NAFLD. METHODS: We included 75 morbidly obese patients with biopsy-proven NAFLD (41 with histologic non-alcoholic steatohepatitis (NASH)) with clinical and laboratory data as well as frozen serum samples from the time of liver biopsy. Fasting serum was assayed for obestatin as well as acylated and des-acyl-ghrelin concentrations using ELISA. Bio-Plex inflammatory cytokine assays were used to profile expression of 17 inflammatory mediators, including IL-6, IL-7, IL-8, G-CSF, CCL2, and MIP-1ß. RESULTS: Patients with NASH had twofold higher concentration of des-acyl-ghrelin than patients with non-NASH (2.58 vs. 1.24 pg/ml, P < 0.02). Ghrelin concentrations in NASH patients with fibrosis stage ≥2 were almost double the concentration of NASH patients with fibrosis stage <2 (8.73 vs. 4.22 pg/ml, P < 0.04). Obestatin levels also increased with the fibrosis stage (2.54 vs. 3.46 pg/ml, P < 0.03). NAFLD patients with higher fibrosis stage had lower IL-7 concentrations (16.89 vs. 10.68 pg/ml, P = 0.014). Obestatin levels at baseline significantly correlated with rate of weight loss after bariatric surgery at various time points. CONCLUSIONS: This study suggests that products of the GHRL gene may be important for the pathogenesis of NASH and fibrosis. Additional confirmatory studies are needed.

A systems biology approach to the pathogenesis of obesity-related nonalcoholic fatty liver disease using reverse phase protein microarrays for multiplexed cell signaling analysis.

UNLABELLED: Nonalcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease. Omental adipose tissue, a biologically active organ secreting adipokines and cytokines, may play a role in the development of NAFLD. We tested this hypothesis with reverse-phase protein microarrays (RPA) for multiplexed cell signaling analysis of adipose tissue from patients with NAFLD. Omental adipose tissue was obtained from 99 obese patients. Liver biopsies obtained at the time of surgery were all read by the same hepatopathologist. Adipose tissue was exposed to rapid pressure cycles to extract protein lysates. RPA was used to investigate intracellular signaling. Analysis of 54 different kinase substrates and cell signaling endpoints showed that an insulin signaling pathway is deranged in different locations in NAFLD patients. Furthermore, components of insulin receptor-mediated signaling differentiate most of the conditions on the NAFLD spectrum. For example, PKA (protein kinase A) and AKT/mTOR (protein kinase B/mammalian target of rapamycin) pathway derangement accurately discriminates patients with NASH from those with the non-progressive forms of NAFLD. PKC (protein kinase C) delta, AKT, and SHC phosphorylation changes occur in patients with simple steatosis. Amounts of the FKHR (forkhead factor Foxo1)phosphorylated at S256 residue were significantly correlated with AST/ALT ratio in all morbidly obese patients. Furthermore, amounts of cleaved caspase 9 and pp90RSK S380 were positively correlated in patients with NASH. Specific insulin pathway signaling events are altered in the adipose tissue of patients with NASH compared with patients with nonprogressive forms of NAFLD. CONCLUSION: These findings provide evidence for the role of omental fat in the pathogenesis, and potentially, the progression of NAFLD.

A genomic and proteomic study of the spectrum of nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and some of its forms are progressive. This study describes the profiling of hepatic gene expression and serum protein content in patients with different subtypes of NAFLD. Liver biopsy specimens from 98 bariatric surgery patients were classified as normal, steatosis alone, steatosis with nonspecific inflammation, and nonalcoholic steatohepatitis (NASH). Microarray hybridizations were performed in triplicate and the microarray expression levels of a selected group of genes were confirmed using real-time quantitative reverse-transcriptase polymerase chain reaction. Serum protein profiles of the same patients were determined by SELDI-TOF mass spectrometry. Of 98 obese patients, 91 were diagnosed with NAFLD (12 steatosis alone, 52 steatosis with nonspecific inflammation, and 27 NASH), and 7 patients without NAFLD served as obese controls. Each group of NAFLD patients was compared with the obese controls, and 22 genes with more than twofold differences in expression levels were revealed. Proteomics analyses were performed for the same group comparisons and revealed twelve significantly different protein peaks. In conclusion, this genomic/proteomic analysis suggests differential expression of several genes and protein peaks in patients within and across the forms of NAFLD. These findings may help clarify the pathogenesis of NAFLD and identify potential targets for therapeutic intervention.