Progranulin serum levels and gene expression in subcutaneous vs visceral adipose tissue of severely obese patients undergoing bariatric surgery

Abstract

Background Progranulin represents an adipokine putatively mediating insulin resistance and inflammation. Data in humans are sparse, and the source of circulating progranulin in obesity is unknown. Objectives Serum progranulin concentrations and subcutaneous (sc) as well as visceral (vis) adipose tissue (AT) progranulin expression were quantified in a large cohort of patients with obesity undergoing bariatric surgery (BS) (n = 153) or a low‐calorie diet (LCD) (n = 121). Cohorts and methods Paired serum and AT mRNA samples were obtained from patients with severe obesity undergoing BS (ROBS cohort; Research in Obesity and Bariatric Surgery). Serum progranulin was measured by ELISA in both cohorts, and AT mRNA expression was analysed by quantitative real‐time PCR in bariatric patients. Results There was no gender‐specific effect in serum progranulin or AT progranulin expression. Importantly, circulating progranulin was independent from adipose tissue gene expression in paired samples. sc AT progranulin expression was higher than in vis AT (P = 0.027), and there was a positive correlation between sc AT and vis AT gene expression (P < 0.001; r = +0.34). Serum progranulin strongly and rapidly increased after BS within 3 days and remained elevated up to 12 months. Serum progranulin was strongly correlated with serum CTRP‐3 levels. Conclusions The present study provides detailed progranulin gene expression data in sc and vis AT in a large, prospective and observational cohort of patients with severe obesity. Serum progranulin concentrations are not predicted by sc or vis AT progranulin gene expression. Thus, AT seems not to be the main source of circulating progranulin levels in obesity.

Downregulation of CTRP-3 by Weight Loss In Vivo and by Bile Acids and Incretins in Adipocytes In Vitro

“…Bariatric surgery and LCD resulted in a highly significant weight loss at V12 when compared to baseline levels, as it was reported earlier for a smaller subgroup of the same study cohort [23]. On average, bariatric surgery patients lost 56.5 ± 17.1 kg and LCD patients lost 30.3 ± 15.6 kg.…”

“…The ROBS study cohort has been introduced recently, more detailed information concerning outline and study characteristics can be retrieved from the literature [23]. Briefly, serum samples and specimens from subcutaneous (abdominal) and visceral (intra-abdominal) adipose tissue were collected from the ROBS study cohort which represents an open-label, non-randomized, prospective, and observational (explorative and confirmatory) study of patients routinely undergoing either bariatric surgery (gastric sleeve or Roux-en-Y gastric bypass; n = 179) or a low-calorie formula diet (n = 131) in a single tertiary care center at the University of Giessen, Germany.…”

“…A large and well-characterized obesity study cohort (Research in Obesity and Bariatric Surgery, ROBS) has been established at the University Obesity Center, Giessen, Germany [23]. The ROBS study comprises obese patients undergoing either bariatric surgery (n = 179; RYGB or gastric sleeve (GS)) or life-style intervention including a low-calorie formula diet (LCD; n = 131).…”

Serum Levels and Adipose Tissue Gene Expression of Cathelicidin Antimicrobial Peptide (CAMP) in Obesity and During Weight Loss

“…Total mRNA was isolated from frozen human subcutaneous and visceral adipose tissue. Human subcutaneous and visceral adipose tissue was resected in obese patients undergoing bariatric surgery and participating in the ROBS study cohort [8]. Gene expression was quantified by reverse transcription of 300 ng RNA (QuantiTect Reverse Transcription Kit from Qiagen, Hilden, Germany) and subsequent real-time PCR (RT-PCR) (iTaq Universal SYBR Green Supermix, CFX Connect RT-PCR system; Bio-Rad, Munich, Germany) of the corresponding cDNA as mentioned below in detail.…”

“…Since reference values of human serum CAMP concentrations have not yet been evaluated in the literature systematically, basal CAMP concentrations were measured in two large cohorts of patients undergoing either BS (n = 156; 122 females, 34 males; mean age: 40.1 ± 11.0 years; mean BMI: 53.6 ± 6.6 kg/m 2 ; BMI range: 40.9-83.7 kg/m 2 ) or LCD (n = 79; 51 females, 28 males; mean age: 42.0 + 12.1 years; mean BMI: 44.0 ± 5.5 kg/m 2 ; BMI range: 31.9-59.2 kg/m 2 ). The detailed study characteristics can be drawn from a recent publication [8]. ▶table 1 summarizes mean values ± SEM/ SD, median, range, variance and gender-specific concentrations of CAMP at a glance.…”