Adipose tissue and atherosclerosis

Cholesterol in the Cell Membrane-An Emerging Player in Atherogenesis

Membrane cholesterol is essential for cell membrane properties, just as serum cholesterol is important for the transport of molecules between organs. This review focuses on cholesterol transport between lipoproteins and lipid rafts on the surface of macrophages. Recent studies exploring this mechanism and recognition of the central dogma-the key role of macrophages in cardiovascular disease-have led to the notion that this transport mechanism plays a major role in the pathogenesis of atherosclerosis. The exact molecular mechanism of this transport remains unclear. Future research will improve our understanding of the molecular and cellular bases of lipid raft-associated cholesterol transport.

Assessment of Zinc- alpha2 glycoprotein (ZAG) and Lipase Maturation Factor 1 (LMF1) concentration in children with chronic kidney disease

ZAG (zinc-alpha2-glycoprotein) - adipokine, may participate in the mechanism of malnutrition in chronic kidney disease (CKD) as cachexia factor. The transmembrane protein of the endoplasmic reticulum - lipase maturation factor 1 (LMF1) is necessary for the secretion and enzymatic activity of lipases and lowering triglycerides level. The aim of the study was to evaluate these markers - ZAG and LMF1, their potential importance in CKD in children. The study included 59 children and adolescents aged 10.7±5.0 years with CKD. Compared with healthy children, serum and urine ZAG levels were higher in children with CKD. A similar relationship was obtained in the comparison of girls and boys between the above groups. We showed a reduced serum and urine concentration of LMF1 in children with CKD. Additionally, ZAG and LMF1 levels in children below 10 years of age and above 10 were no different. There was also no correlation between these markers and serum creatinine (except negative correlation of urinary ZAG), albumin, cholesterol, triglycerides. LMF1 concentration correlated positively with vitamin D level in dialyzed patients. To conclude, elevated serum ZAG levels in children with CKD document that selective kidney damage results in the rise of ZAG concentration, however the specific role of this marker in malnutrition was not documented. Reduced serum LMF1 concentration in children with CKD, did not correlate with standard parameters used to assess lipid metabolism and severity of CKD. The usefulness of LMF1 as the marker of the lipid metabolism disturbances in children with CKD was not proven.

Decreased infiltration of adipose tissue macrophages and amplified inflammation of adipose tissue in obese mice with severe acute pancreatitis

OBJECTIVE

Macrophages are involved in obesity-associated inflammation and severe acute pancreatitis (SAP) development. However, the role of adipose tissue macrophages (ATMs) in obesity-related SAP has not been fully elucidated. We investigated the relationship between ATMs and inflammatory responses in SAP model mice fed a high-fat diet (HFD).

METHODS

SAP was induced in animal models via intraperitoneal injections of caerulein and lipopolysaccharide (LPS). SAP severity was evaluated, both morphologically and biochemically, and macrophage infiltration in the pancreas and epididymal adipose tissue was measured. We also analyzed apoptosis levels, polarization of the ATMs, and expression of inflammatory mediators in epididymal adipose tissue.

RESULTS

Obesity increased disease severity in SAP animals. Increased macrophage infiltration in the pancreas induced by SAP was found in both normal diet (ND)- and HFD-fed mice. Total ATM infiltration in epididymal adipose tissue was elevated by HFD, while a significant decrease in infiltration was observed in both the ND + SAP and HFD + SAP groups. The apoptosis levels of ATMs were reduced in the HFD group, but were markedly enhanced in both the ND + SAP and HFD + SAP groups compared to their respective control groups. Higher levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) were observed in the HFD + SAP than in the ND + SAP group. Increased proportion of M1 type ATMs was induced by both HFD and SAP.

CONCLUSIONS

Total ATM infiltration was decreased in epididymal adipose tissue of SAP animals. ATM polarization to the M1 type resulted in an amplified inflammatory response in obese mice with SAP.

Body composition of women with and without dynapenia defined by different cut-off points

ABSTRACT Objective To compare body composition of postmenopausal women with and without dynapenia, defined by different cut-off points. Methods Body composition was assessed by electrical bioimpedance and the nutritional status by the body mass index. Dynapenia was diagnosed according to handgrip strength, using the following cut-off points: handgrip strength <16kgf and <20 kgf. Results A total of 171 women (50 to 92 years of age) participated in the investigation. The mean age of non-dynapenic and dynapenic women (handgrip strength <20kgf) was 69.4±8.2 and 74.5±8.2 years, respectively. The mean age of women with dynapenia (handgrip strength <16kgf) was 75.0±10.1 years and non-dynapenic women, 71.1±8.2 years. It was found that dynapenic women, with handgrip strength <20 and <16kgf, had an average of 2.38 and 2.47kg less muscle mass respectively, when compared to non-dynapenic women (p<0.05). However, there was no difference in muscle mass between the different dynapenic groups. Non-dynapenic women (handgrip strength ≥20kgf) had more total (3.55kg) and central fat (1.47kg) (p<0.05). Conclusion Dynapenic women, diagnosed considering both cutoff points, had less total and segmental muscle mass compared to non-dynapenic women. In addition, dynapenic women with handgrip strength <20kgf had lower total and trunk adiposity.

Associations Between Homeostasis Model Assessment (HOMA) and Routinely Examined Parameters in Individuals With Metabolic Syndrome

The aim of the study was to investigate whether routine clinical parameters, including visceral adiposity index (VAI) and atherogenic index of plasma (AIP), could become widely applicable predictors of insulin resistance (IR), evaluated using homeostasis model assessment (HOMA-IR, HOMA-β), with regard to presence of metabolic syndrome (MS). The study comprised 188 individuals identified to meet the MS criteria during regular health examinations and an equal number of age, sex-matched controls without MS. The strongest correlations were noted between HOMA-IR and waist circumference (WC) in the MS group (r=0.57) as well as between HOMA-IR and alanine aminotransferase (ALT, r=0.57) or aspartate aminotransferase (r=0.56) in the controls, with a statistical significance of p<0.001. In a multivariate linear regression model, the predictors of HOMA-IR were WC (linear coefficient β=0.1, p<0.001), ALT (β=2.28, p<0.001) and systolic blood pressure (β=0.04, p<0.001). HOMA-β was determined by WC (β=1.97, p=0.032) and ALT (β=99.49, p=0.004) and inversely associated with age (β=-1.31, p=0.004). Neither VAI nor AIP were significant predictors. The presence of MS was significantly associated with both HOMA-IR and HOMA-β. These results indicate that WC and ALT appear to be reliable predictors of IR. Comprehensive assessment of these parameters may serve for estimating the level of IR.

Attenuation of oxidative stress-induced lesions in skeletal muscle in a mouse model of obesity-independent hyperlipidaemia and atherosclerosis through the inhibition of Nox2 activity

Obesity leading to hyperlipidaemia and atherosclerosis is recognised to induce morphological and metabolic changes in many tissues. However, hyperlipidaemia can occur in the absence of obesity. The impact of the latter scenario on skeletal muscle and liver is not understood sufficiently. In this regard, we used the Apolipoprotein E-deficient (ApoE^-/-) mouse model, an established model of hyperlipidaemia and atherosclerosis, that does not become obese when subjected to a high-fat diet, to determine the impact of Western-type diet (WD) and ApoE deficiency on skeletal muscle morphological, metabolic and biochemical properties. To establish the potential of therapeutic targets, we further examined the impact of Nox2 pharmacological inhibition on skeletal muscle redox biology. We found ectopic lipid accumulation in skeletal muscle and the liver, and altered skeletal muscle morphology and intramuscular triacylglycerol fatty acid composition. WD and ApoE deficiency had a detrimental impact in muscle metabolome, followed by perturbed gene expression for fatty acid uptake and oxidation. Importantly, there was enhanced oxidative stress in the skeletal muscle and development of liver steatosis, inflammation and oxidative protein modifications. Pharmacological inhibition of Nox2 decreased reactive oxygen species production and protein oxidative modifications in the muscle of ApoE^-/- mice subjected to a Western-type diet. This study provides key evidence to better understand the pathophysiology of skeletal muscle in the context of hyperlipidaemia and atherosclerosis and identifies Nox2 as a potential target for attenuating oxidative stress in skeletal muscle in a mouse model of obesity-independent hyperlipidaemia.

Resident and Monocyte-Derived Macrophages in Cardiovascular Disease

Macrophages are ubiquitous cells that reside in all major tissues. Counter to long-held beliefs, we now know that resident macrophages in many organs are seeded during embryonic development and self-renew independently from blood monocytes. Under inflammatory conditions, those tissue macrophages are joined and sometimes replaced by recruited monocyte-derived macrophages. Macrophage function in steady state and disease depends on not only their developmental origin but also the tissue environment. Here, we discuss the ontogeny, function, and interplay of tissue-resident and monocyte-derived macrophages in various organs contributing to the development and progression of cardiovascular disease.

Crossroads between peripheral atherosclerosis, western-type diet and skeletal muscle pathophysiology: emphasis on apolipoprotein E deficiency and peripheral arterial disease

Atherosclerosis is a chronic inflammatory process that, in the presence of hyperlipidaemia, promotes the formation of atheromatous plaques in large vessels of the cardiovascular system. It also affects peripheral arteries with major implications for a number of other non-vascular tissues such as the skeletal muscle, the liver and the kidney. The aim of this review is to critically discuss and assimilate current knowledge on the impact of peripheral atherosclerosis and its implications on skeletal muscle homeostasis. Accumulating data suggests that manifestations of peripheral atherosclerosis in skeletal muscle originates in a combination of increased i)-oxidative stress, ii)-inflammation, iii)-mitochondrial deficits, iv)-altered myofibre morphology and fibrosis, v)-chronic ischemia followed by impaired oxygen supply, vi)-reduced capillary density, vii)- proteolysis and viii)-apoptosis. These structural, biochemical and pathophysiological alterations impact on skeletal muscle metabolic and physiologic homeostasis and its capacity to generate force, which further affects the individual's quality of life. Particular emphasis is given on two major areas representing basic and applied science respectively: a)-the abundant evidence from a well-recognised atherogenic model; the Apolipoprotein E deficient mouse and the role of a western-type diet and b)-on skeletal myopathy and oxidative stress-induced myofibre damage from human studies on peripheral arterial disease. A significant source of reactive oxygen species production and oxidative stress in cardiovascular disease is the family of NADPH oxidases that contribute to several pathologies. Finally, strategies targeting NADPH oxidases in skeletal muscle in an attempt to attenuate cellular oxidative stress are highlighted, providing a better understanding of the crossroads between peripheral atherosclerosis and skeletal muscle pathophysiology.

Total control of fat cells from adipogenesis to apoptosis using a xanthene analog

Overcrowded adipocytes secrete excess adipokines and cytokines under stress, which results in a deregulated metabolism. This negative response to stress increases the possibility of obesity and several of its associated diseases, such as cancer and atherosclerosis. Therefore, a reduction in the number of adipocytes may be a rational strategy to relieve the undesired expansion of adipose tissue. A newly synthesized xanthene analog, MI-401, was found to have two distinct effects on the regulation of the adipocyte’s life cycle. MI-401 efficiently down regulated the expression of transcription factors, PPARγ and C/EBPα, and lipogenesis proteins, FAS and FABP4. This down regulation resulted in the inhibition of adipogenesis. Without newly differentiated adipocytes, the total number of adipocytes will not increase. In addition to this inhibitory effect, MI-401 was able to actively kill mature adipocytes. It specifically triggered apoptosis in adipocytes at low micro molar concentration and spared preadipocytes and fibroblasts. These dual functionalities make MI-401 an effective agent in the regulation of the birth and death of adipocytes.