Adipokines and proinflammatory cytokines, the key mediators in the pathogenesis of nonalcoholic fatty liver disease

Table 4 Studies and their findings on resistin, visfatin and retinol binding protein 4

Adipocytokines	Finding	Ref.
Resistin	Resistin levels increased in morbidly obese humans	[142]
	Resistin levels in T2DM patients 20% higher when compared to non-diabetic patients	[144]
	No correlation between resistin and components of MS on T2DM patients	[145]
	Resistin did not correlate with BMI but significantly correlated with IR	[146]
	G/G -180C>G homozygotes for resistin had significantly higher resistin mRNA levels in abdominal subcutaneous fat	[148]
	Serum resistin levels not associated with the presence of NASH	[149]
	Serum resistin levels higher in NAFLD that in controls and positively correlated with liver inflammation and fibrosis severity	[118,150]
	Resistin serum levels in NAFLD patients were associated with histological severity of the disease but not with IR	[151]
	Expression of resistin in human peripheral-blood mononuclear cells upregulated by TNF-α and IL-6	[152]
Visfatin	Secretion of visfatin enhanced by glucose administration	[153]
	Plasma visfatin elevated in patients with T2DM	[154]
	Visfatin plasma concentrations markedly elevated in obese subjectsBariatric surgery reduced body mass index, visfatin, leptin and increased adiponectin after 6 mo	[155]
	Plasma visfatin levels elevated in subjects with MS	[156]
	Significantly higher visfatin mRNA in visceral fat of obese subjects compared with lean controls, and positively correlated with body mass index	[158]
	Visfatin level lower in NASH compared to NAFLD patients and healthy controls	[159]
	Visfatin level positively correlated with portal inflammation	[160]
Retinol binding protein 4	Serum RBP4 concentration elevated in IR, obese humans, T2DM and in subjects with a strong family history of T2DM	[161,162]
	Strong association of increased circulating RBP4 levels with IR and MS	[163-166]
	No connection of RBP4 with obesity, IR, or components of the MS	[167-171]
	RBP4 levels associated with inflammatory response in obese individuals	[168,172]
	Circulating RBP4 levels higher in subjects with NAFLDRBP4 liver expression higher in moderate/severe NASH compared to mild forms	[173]
	RBP4 level a risk factors for fibrosis ≥ 2 in NASHRBP4 and HOMA-IR independently associated with steatosis in patients with chronic hepatitis C	[174]
	In NAFLD patients, serum RBP4 significantly lower compared with controls, did not correlate with IRRBP4 liver tissue expression enhanced in NAFLD patients and correlated with NAFLD histology	[175]
	Serum RBP4 levels did not correlate with BMI, HOMA-IR, fasting blood glucose, or insulin levels in patients with simple steatosis and NASHPatients with cirrhosis and fibrosis had higher RBP4 compared to controls	[176,177]

T2DM: Type 2 diabetes mellitus; MS: Metabolic syndrome; NASH: Nonalcoholic steatohepatitis; NAFLD: Non-alcoholic fatty liver disease; IR: Insulin resistance; TNF-α: Tumor necrosis factor alpha; IL-6: Interleukin 6; RBP4: Retinol binding protein 4; HOMA-IR: Homeostasis model assessment-estimated insulin resistance.