Adiponectin isoforms, insulin resistance and liver histology in nonalcoholic fatty liver disease.
BACKGROUND
Nonalcoholic fatty liver disease is associated with insulin resistance and low adiponectin levels. Adiponectin circulates as high-, medium- and low-molecular weight complexes, possibly exerting different insulin-sensitising effects.


OBJECTIVE
We investigated adiponectin isoforms in nonalcoholic fatty liver disease in relation to liver disease severity and insulin resistance.


METHODS
Total adiponectin and isoform distribution were measured in 54 biopsy-proven, non-diabetic nonalcoholic fatty liver disease subjects, divided according to their fasting and 120-min glucose levels during an oral glucose tolerance test, as well as in 44 matched healthy controls. Insulin resistance/sensitivity was estimated in nonalcoholic fatty liver disease by the homeostasis model assessment and the oral glucose insulin sensitivity during oral glucose tolerance test. Total adiponectin and adiponectin isoforms were determined by in-house assays.


RESULTS
Total adiponectin was reduced in nonalcoholic fatty liver disease (5.32±1.85 mg/L vs. 9.11±3.46 mg/L), with a relative abundance of high-molecular weight (34% vs. 47%) and low-molecular weight adiponectin (16% vs. 19%), coupled with dearth of medium-molecular weight adiponectin (50% vs. 34%) (P<0.001 for all comparisons). In nonalcoholic fatty liver disease, adiponectin did not differ in relation to homeostasis model assessment, but levels were remarkably higher in relation to oral glucose insulin sensitivity-determined insulin sensitivity. However, the distribution of isoforms did not vary with disease severity, BMI class, glucose regulation or insulin resistance.


CONCLUSIONS
Adiponectin levels are reduced in nonalcoholic fatty liver disease, without any significant contribution of isoform distribution to progressive liver disease.
Bianchi
Giampaolo
G
Department of Internal Medicine, "Alma Mater Studiorum" University, Bologna, Italy. giampaolo.bianchi@unibo.it
Bugianesi
Elisabetta
E
Frystyk
Jan
J
Tarnow
Lise
L
Flyvbjerg
Allan
A
Marchesini
Giulio
G
D052242:Adiponectin / Q000097:blood*; D000328:Adult; D001786:Blood Glucose; D016009:Chi-Square Distribution; D005234:Fatty Liver / Q000097:blood / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease; D020033:Protein Isoforms / Q000097:blood; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric
D052242:Adiponectin; D001786:Blood Glucose; D007328:Insulin; D020033:Protein Isoforms