Diego Lucero

Pro-inflammatory and atherogenic circulating factors in non-alcoholic fatty liver disease associated to metabolic syndrome

BACKGROUND It is not elucidated if liver fat deposits associated to metabolic syndrome (MS) aggravate the atherogenic state. We evaluated, in MS patients, if the presence of non-alcoholic hepatic steatosis (HS) determines differences in inflammatory markers and VLDL characteristics. METHODS Seventy-five patients with MS were divided into 2 groups depending on the presence or absence of HS, assessed by ultrasound. Lipid profile, free fatty acids (FFA), VLDL composition, adiponectin, tumor necrosis factor-alpha (TNF-α), high sensitivity C-reactive protein (hs-CRP), and soluble adhesion molecules (sVCAM-1 and sICAM-1) were measured. RESULTS HS patients presented increased triglycerides levels, HOMA-IR and FFA. Patients with HS showed a reduction in adiponectin (p = 0.04) and increase in hs-CRP (p = 0.02), independently of insulin-resistance (IR). FFA correlated positively with TNF-α (p = 0.04) and inversely with adiponectin (p = 0.01). hs-CRP correlated with all inflammatory markers, independently of IR: TNF-α (r = 0.34, p = 0.02), sVCAM-1 (r = 0.29 p = 0.03), sICAM-1 (r = 0.56, p = 0.01), adiponectin (r = -0.34, p = 0.04). HS patients presented higher VLDL mass and number of particles. Adiponectin correlated with VLDL cholesterol content (r = -0.47, p = 0.04), independently of IR. VLDL, once secreted, would suffer from changes, becoming more atherogenic. CONCLUSIONS Simple HS would play an important role increasing cardiovascular risk, independently of IR. hs-CRP may represent a useful biomarker of this condition.

Hepatic lipase activity is increased in non-alcoholic fatty liver disease beyond insulin resistance.

Hepatic lipase is a lipolytic enzyme mostly synthesized and localized at the surface of liver sinusoidal capillaries, which hydrolyses triglycerides and phospholipids of intermediate density, large low density (LDL) and high density lipoproteins. Hepatic lipase activity is increased in insulin resistant states. Non‐alcoholic fatty liver disease (NAFLD) is characterized by insulin resistance. However, at present, no data are available regarding the behaviour of hepatic lipase with regard to the degree of hepatic steatosis. Our aim was to evaluate hepatic lipase activity in NAFLD patients and its relationship to the severity of hepatic steatosis.

Does non-alcoholic fatty liver impair alterations of plasma lipoproteins and associated factors in metabolic syndrome?

BACKGROUND Hepatic steatosis (HS) is closely associated to metabolic syndrome (MS). Both, VLDL-triglyceride oversecretion and intrahepatic deposits, can take place. We evaluated VLDL characteristics, CETP, hepatic lipase (HL), IDL and small dense LDL (sdLDL), in patients with HS associated to MS. METHODS We studied 3 groups matched by age and sex: 25 MS patients with HS (diagnosed by ultrasonography), 25 MS patients without HS and 25 healthy controls. Main measurements were: lipid profile, free fatty acids, VLDL composition, VLDL size by HPLC, CETP and HL activities, IDL-cholesterol and sdLDL-cholesterol. RESULTS Patients with HS presented higher triglyceride levels, HOMA-IR and free fatty acids, VLDL mass and VLDL-apoB (p<0.05). No differences in VLDL composition were observed. MS groups presented higher proportion of large VLDL than controls (p<0.05). HS group showed higher CETP than controls (p=0.01) and almost higher than MS without HS (p=0.06). CETP correlated with VLDL-cholesterol content, r=0.48, p<0.005. The increase in sdLDL-cholesterol correlated with CETP (r=0.47) and HL (r=0.56), independent of insulin resistance (p<0.003). CONCLUSION Despite intrahepatic fat, patients with HS secreted higher number of VLDL particles. CETP would have a remodeling action on VLDL in circulation, enriching it in cholesterol and also favoring, together with HL, the formation of sdLDL.

New evidence for the therapeutic potential of curcumin to treat nonalcoholic fatty liver disease in humans.

Introduction The immune system acts on different metabolic tissues that are implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Leptin and linoleic acid have the ability to potentially affect immune cells, whereas curcumin is a known natural polyphenol with antioxidant and anti-inflammatory properties. Aims This study was designed to evaluate the pro-inflammatory and pro-oxidant effects of leptin and linoleic acid on immune cells from patients with NAFLD and to corroborate the modulatory effects of curcumin and its preventive properties against the progression of NAFLD using a high-fat diet (HFD)-induced NAFLD/nonalcoholic steatohepatitis mouse model. Results The ex vivo experiments showed that linoleic acid increased the production of reactive oxygen species in monocytes and liver macrophages, whereas leptin enhanced tumor necrosis factor-α (TNF-α) production in monocytes and interferon-γ production in circulating CD4+ cells. Conversely, oral administration of curcumin prevented HFD-induced liver injury, metabolic alterations, intrahepatic CD4+ cell accumulation and the linoleic acid- and leptin- induced pro-inflammatory and pro-oxidant effects on mouse liver macrophages. Conclusion Our findings provide new evidence for the therapeutic potential of curcumin to treat human NAFLD. However, the development of a preventive treatment targeting human circulating monocytes and liver macrophages as well as peripheral and hepatic CD4+ cells requires additional research.

Nonalcoholic fatty liver disease associated with metabolic syndrome: Influence of liver fibrosis stages on characteristics of very low-density lipoproteins

BACKGROUND We evaluated possible changes in VLDLcharacteristics, and metabolic related factors, in MetS-associated NAFLD and accompanying liver fibrosis. METHODS We studied 36 MetS patients with biopsy-proven NAFLD (MetS+NAFLD) and 24 MetS without ultrasound NAFLD evidence. Further, MetS+NAFLD was sub-divided according to fibrosis stage into, non-to-moderate (F0-F2, n=27) and severe (F3-F4, n=9) fibrosis. We measured: lipid profile, VLDL composition and size (size exclusion-HPLC), CETP and lipoprotein lipase (LPL) activities and adiponectin. Additionally, in MetS+NAFLD type IV collagen 7S domain was measured. RESULTS MetS+NAFLD showed increased VLDL-mass, VLDL particle number, VLDL-triglyceride% and large VLDL-% (p<0.04). CETP activity tended to increase in MetS+NAFLD (p=0.058), while LPL activity was unchanged. Moreover, in MetS+NAFLD, adiponectin was decreased (p<0.001), and negatively correlated with VLDL-mass and VLDL particle number (p<0.05), independently of insulin-resistance. Within MetS+NAFLD group, despite greater insulin-resistance, patients with severe fibrosis showed lower plasma triglycerides, VLDL-mass, VLDL-triglyceride%, large VLDL-% and CETP activity (p<0.05), while type IV collagen was increased (p=0.009) and inversely correlated with large VLDL-% (p=0.045). CONCLUSIONS In MetS, NAFLD is associated with larger and triglyceride over-enriched circulating VLDLs, of greater atherogenicity. However, when NAFLD progresses to severe fibrosis, circulating VLDL features apparently improved, probably due to early alterations in hepatic synthetic function.

Role of SN1 Lipases on Plasma Lipids in Metabolic Syndrome and Obesity

Objective— To assess the phospholipase activity of endothelial (EL) and hepatic lipase (HL) in postheparin plasma of subjects with metabolic syndrome (MS)/obesity and their relationship with atherogenic and antiatherogenic lipoproteins. Additionally, to evaluate lipoprotein lipase (LPL) and HL activity as triglyceride (TG)-hydrolyses to complete the analyses of SN1 lipolytic enzymes in the same patient. Approach and Results— Plasma EL, HL, and LPL activities were evaluated in 59 patients with MS and 36 controls. A trend toward higher EL activity was observed in MS. EL activity was increased in obese compared with normal weight group (P=0.009) and was negatively associated with high-density lipoprotein–cholesterol (P=0.014 and P=0.005) and apolipoprotein A-I (P=0.045 and P=0.001) in control and MS group, respectively. HL activity, as TG-hydrolase, was increased in MS (P=0.025) as well as in obese group (P=0.017); directly correlated with low-density lipoprotein–cholesterol (P=0.005) and apolipoprotein B (P=0.003) and negatively with high-density lipoprotein–cholesterol (P=0.021) in control group. LPL was decreased in MS (P<0.001) as well as in overweight and obese compared with normal weight group (P=0.015 and P=0.004, respectively); inversely correlated %TG-very low-density lipoproteins (P=0.04) and TG/apolipoprotein B index (P=0.013) in control group. These associations were not found in MS. Conclusions— We describe for the first time EL and HL activity as phospholipases in MS/obesity, being both responsible for high-density lipoprotein catabolism. Our results elucidate part of the remaining controversies about SN1 lipases activity in MS and different grades of obesity. The impact of insulin resistance on the activity of the 3 enzymes determines the lipoprotein alterations observed in these states.

Role of HDL in neutralizing the VLDL effect on endothelial dysfunction

OBJECTIVE It has been reported that LDL inhibits endothelium-dependent relaxation (EDR) and that HDL can neutralize this effect. However, the atherogenic properties of VLDL have been so far difficult to demonstrate. Studies on VLDL are controversial, and nothing is known about the role of HDL on potential VLDL vascular actions. We examined the effect of human VLDLs on EDR, and the role of HDL in this system. METHODS VLDL (n=14) and LDL (n=6) were isolated from volunteer subjects. Normal HDL was obtained from one healthy donor. VLDL ability to inhibit ACh-induced vasorelaxation (10(-9)-10(-5)mM) on aortic rings previously precontracted by noradrenaline (10(-8)mM) was measured in the presence and absence of HDL. RESULTS ACh-induced maximal relaxation (R%) was mildly, but not significantly attenuated in the presence of VLDL (72±7%), while LDL caused a significant inhibition (60±10%, p<0.05) when compared to incubation in the absence of lipoproteins. VLDLs were subdivided into 2 groups depending on their cholesterol/triglyceride ratio: 0.18-0.22 (n=8) was considered typical and 0.10-0.15, rich in triglycerides (VLDLRT, n=6). Typical VLDL had no effect on EDR (p=0.38), however R% from VLDLRT was lower (54±7%, p<0.01) similar to the one obtained with LDL (p=0.32). HDL showed favorable effects on EDR inhibition induced by the presence of VLDLRT (p<0.05.). CONCLUSION Although typical VLDL did not cause endothelial dysfunction, triglyceride-enriched VLDL had inhibitory effect on EDR. It is proposed that alterations in VLDL composition would increase its atherogenic capacity. Moreover HDL appears to protect endothelium from VLDL action.

Adiponectin predicts MMP-2 activity independently of obesity

Matrix metalloproteinases (MMPs), especially MMP‐2 and MMP‐9, have been identified in atherosclerotic plaques and have been directly associated with plaque remodelling and vulnerability. Cardiovascular disease (CVD) is related to insulin resistance (IR) and obesity, characterized by changes in plasma levels of inflammatory markers, such as adiponectin and C‐reactive protein (CRP). Our aim was to evaluate the impact of both proteins on MMP‐2 and MMP‐9 behaviour in individuals with IR.

Overproduction of altered VLDL in an insulin-resistance rat model: Influence of SREBP-1c and PPAR-α

BACKGROUND In insulin-resistance, VLDL presents alterations that increase its atherogenic potential. The mechanism by which insulin-resistance promotes the production of altered VLDL is still not completely understood. The aim of this study was to evaluate the relationship between the expression of sterol regulatory element binding protein 1c (SREBP-1c) and of peroxisome proliferator-activated receptor-α (PPAR-α), with the features of composition and size of VLDL in an insulin-resistance rat model induced by a sucrose rich diet (SRD). METHODS The study was conducted on 12 male Wistar rats (180g) receiving SRD (12 weeks) and 12 controls. Lipid profile, free fatty acids, glucose, and insulin were measured. Lipid content in liver and visceral fat were assessed. Isolated VLDL (d<1.006g/ml) was characterized by its chemical composition and size by HPLC. The respective hepatic expression of SREBP-1c and PPAR-α was determined (Western blot). RESULTS As expected, SRD had elevated triglycerides (TG), free fatty acids and insulin levels, and decreased HDL-cholesterol (p<0.05), together with augmented hepatic and visceral fat (p<0.05). SRD showed higher VLDL total mass - with increased TG content - and predominance of large VLDL (p<0.05). SRD showed an increase in SREBP-1c (precursor and mature forms) and decreased PPAR-α expression (p<0.045). SREBP-1c forms were positively associated with VLDL total mass (p<0.04), VLDL-TG% (p<0.019), and large VLDL% (p<0.002). On the other hand, PPAR-α correlated negatively with VLDL total mass (p=0.05), VLDL-TG% (p=0.005), and large VLDL% (p=0.002). CONCLUSIONS Insulin-resistance, by coordinated activation of SREBP-1c and reduction of PPAR-α, could promote the secretion of larger and TG over-enriched VLDL particles, with greater atherogenic capacity.