Pioglitazone in the treatment of NASH: the role of adiponectin.
BACKGROUND
Plasma adiponectin is decreased in NASH patients and the mechanism(s) for histological improvement during thiazolidinedione treatment remain(s) poorly understood.


OBJECTIVE
To evaluate the relationship between changes in plasma adiponectin following pioglitazone treatment and metabolic/histological improvement.


METHODS
We measured in 47 NASH patients and 20 controls: (i) fasting glucose, insulin, FFA and adiponectin concentrations; (ii) hepatic fat content by magnetic resonance spectroscopy; and (iii) peripheral/hepatic insulin sensitivity (by double-tracer oral glucose tolerance test). Patients were then treated with pioglitazone (45 mg/day) or placebo and all measurements were repeated after 6 months.


RESULTS
Patients with NASH had decreased plasma adiponectin levels independent of the presence of obesity. Pioglitazone increased 2.3-fold plasma adiponectin and improved insulin resistance, glucose tolerance and glucose clearance, steatosis and necroinflammation (all P < 0.01-0.001 vs. placebo). In the pioglitazone group, plasma adiponectin was significantly associated (r = 0.52, P = 0.0001) with hepatic insulin sensitivity and with the change in both variables (r = 0.44, P = 0.03). Increase in adiponectin concentration was related also to histological improvement, in particular, to hepatic steatosis (r = -0.46, P = 0006) and necroinflammation (r = -0.56, P < 0.0001) but importantly also to fibrosis (r = -0.29, P = 0.03).


CONCLUSIONS
Adiponectin exerts an important metabolic role at the level of the liver, and its increase during pioglitazone treatment is critical to reverse insulin resistance and improve liver histology in NASH patients.
Gastaldelli
A
A
The University of Texas Health Science Center at San Antonio, 78284-3900, USA.
Harrison
S
S
Belfort-Aguiar
R
R
Hardies
J
J
Balas
B
B
Schenker
S
S
Cusi
K
K
D052242:Adiponectin / Q000097:blood / Q000378:metabolism*; D000328:Adult; D016022:Case-Control Studies; D005234:Fatty Liver / Q000188:drug therapy*; D005951:Glucose Tolerance Test; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D000077205:Pioglitazone; D012044:Regression Analysis; D045162:Thiazolidinediones / Q000627:therapeutic use*; D016896:Treatment Outcome
D052242:Adiponectin; D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D000077205:Pioglitazone