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Background: Obesity is frequently complicated by comorbid conditions, yet how excess adipose contributes is poorly understood. Although adipocytes in obese individuals induce systemic inflammation via secreted cytokines, another potential mediator has recently been identified (i.e., adipocyte-derived exosomes). We hypothesized that adipocyte-derived exosomes contain mediators capable of activating end-organ inflammatory and fibrotic signaling pathways., Methods: We developed techniques to quantify and characterize exosomes shed by adipocytes from seven obese (age: 12-17.5 y, BMI: 33-50 kg/m(2)) and five lean (age: 11-19 y, BMI: 22-25 kg/m(2)) subjects., Results: Abundant exosomal miRNAs, but no mRNAs, were detected. Comparison of obese vs. lean visceral adipose donors detected 55 differentially expressed miRNAs (P < 0.05; fold change ≥|1.2|). qRT-PCR confirmed downregulation of miR-148b (ratio = 0.2 (95% confidence interval = 0.1, 0.6)) and miR-4269 (0.3 (0.1, 0.8)), and upregulation of miR-23b (6.2 (2.2, 17.8)) and miR-4429 (3.8 (1.1-13.4)). Pathways analysis identified TGF-β signaling and Wnt/β-catenin signaling among the top canonical pathways expected to be altered with visceral adiposity based on projected mRNA targets for the 55 differentially expressed miRNAs. A select mRNA target was validated in vitro., Conclusion: These data show that visceral adipocytes shed exosomal-mediators predicted to regulate key end-organ inflammatory and fibrotic signaling pathways.

Objectives: Our previous work demonstrated altered messenger RNA expression of integrin β-5 and -8, using an in silico analysis of publically available data from patients with biliary atresia (BA); however, we were unable to demonstrate statistically significant differences in protein expression because of sample size. In the present study, we repeated the analysis of liver fibrosis and protein expression of the integrins in a larger cohort of patients with BA and compared them with patients undergoing liver biopsy for other diagnoses, with the hypothesis that ≥ 1 of the integrins would be differentially expressed., Methods: Liver specimens were obtained at 2 collaborating institutions. Samples from infants with BA (n = 23) were compared with samples from those who underwent liver biopsy for neonatal hepatitis (n = 9). All of the specimens were analyzed by 2 pathologists (C.R. and R.A.), who were blinded to the diagnoses. Standard Ishak scoring was performed to evaluate fibrosis and inflammation, and immunohistochemical (IHC) positivity was graded from 0 to 4. Comparisons between the IHC positivity and Ishak scoring for the BA and control groups were performed using the Student t test with P < 0.01 considered significant because of the multiple comparisons. Interobserver variability was assessed by intraclass correlation (ICC)., Results: Pooled analysis from specimens from patients with BA showed significantly more fibrosis than controls based on Ishak scores (3.21 ± 1.82 vs 1.17 ± 1.00, P < 0.005). IHC evaluation showed increased integrin ανβ8 protein expression when compared with controls (2.67 ± 0.81 vs 1.72 ± 0.62, P < 0.005); however, there were no significant differences in integrin ανβ5 (1.93 ± 0.84 vs 1.50 ± 0.90, P = 0.23) or integrin ανβ6 (0.85 ± 1.20 vs 0.94 ± 0.85, P = 0.82) expression. These data were confirmed on individual analysis. Interobserver agreement was fair for integrin ανβ5 (ICC 0.52), good for integrin ανβ6 (ICC 0.72), and excellent for integrin ανβ8 (ICC 0.79) and fibrosis (ICC 0.89)., Conclusions: Our data show that integrin ανβ8, but not integrin ανβ5 or integrin ανβ6, protein expression is increased in liver specimens of patients with BA. These data support the mounting evidence that transforming growth factor-β (TGF-β) activation is responsible for the fibrosis found in BA. Anti-integrin ανβ8 or more global integrin blocking strategies may be therapeutic options in BA, but further work is clearly needed.

Introduction: Our previous work demonstrated that the transforming-growth factor (TGF) β pathway plays a central role in the liver fibrosis associated with experimental biliary atresia (BA). To confirm these findings in humans, we performed an in silico analysis of publicly available microarray data from liver specimens from children with BA, with the hypothesis that the TGF-β pathway would be dysregulated., Methods: We analyzed publicly available liver gene expression microarray data from 47 infants with BA. We re-analyzed the microarray image files and clinical data to compare gene expression differences between the fibrogenic and inflammatory cohorts identified in the initial study. Targets from the microarray analysis were confirmed using the animal model of BA., Results: Analysis of variance (ANOVA) detected 6903 transcripts (2822 distinct genes) differentially regulated between groups (p < 0.01; fold change >1.2). We used a targeted approach to identified a subgroup of 24 TGF-β-related transcripts. Expressions for procollagen transcripts were increased in the fibrogenic group (1.2-fold to 1.4-fold); expression of matrix metalloproteinase (MMP)-7 was similarly increased 2-fold, while MMP-9 and plasminogen activator inhibitor-1 were decreased 2-fold and 3-fold respectively. Integrins β5 (1.18-fold) and β8 (1.84-fold) also demonstrated increased expression in the fibrogenic group. Increased expression of β5 (3-fold) and β8 (5-fold) as well as Smad-3 (4-fold) and Smad interacting protein (SIP)-1 (3.5-fold) mRNA was confirmed in experimental BA. Phosphorylated Smad-3 protein in the experimental group was also nearly twice that of the control group, further implicating the TGF-β pathway., Conclusion: Gene transcripts for known upstream and downstream TGF-β mediators are differentially expressed in liver specimens from children with BA and a fibrogenic gene signature. The same integrins that were dysregulated in the human specimens were also found to be up-regulated in our animal BA model, as were other intermediaries in the TGF-β pathway. Further investigation into whether these mediators may be attractive targets for future therapy in children with BA is warranted., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: As the obesity epidemic takes its toll on patients stricken with the disease and our health care system, debate continues regarding the use of weight loss surgery and its long-term consequences, especially for adolescents. One subset of patients regarding whom there is increased controversy is adolescents with extreme obesity (BMI > 60 kg/m(2)) because the risk of complications in this weight category is higher than for others undergoing bariatric surgery. Several strategies have been suggested for this patient group, including staged operations, combined operations, intragastric balloon use, and endoluminal sleeve placement. However, the device options are often not available to adolescents, and there are no data regarding staged or combined procedures in this age group., Methods: All adolescents with BMI >60 kg/m(2) referred to our program were evaluated for inpatient medical weight loss prior to laparoscopic sleeve gastrectomy. The program utilizes a multidisciplinary approach with a protein-sparing modified fast diet, exercise, and behavioral modification., Results: Three patients completed the program, and each achieved significant preoperative weight loss through the inpatient program and successfully underwent bariatric surgery., Conclusions: Presurgical weight loss via an inpatient program for adolescents with a BMI >60 kg/m(2) results in total weight loss comparable to a primary surgical procedure alone, with the benefit of decreasing the perioperative risk.