Association between dietary factors and plasma fetuin-A concentrations in the general population

Interplay between Fatty Acid Binding Protein 4, Fetuin-A, Retinol Binding Protein 4 and Thyroid Function in Metabolic Dysregulation

Signalling between the tissues integrating synthesis, transformation and utilization of energy substrates and their regulatory hormonal axes play a substantial role in the development of metabolic disorders. Interactions between cytokines, particularly liver derived hepatokines and adipokines, secreted from adipose tissue, constitute one of major areas of current research devoted to metabolic dysregulation. The thyroid exerts crucial influence on the maintenance of basal metabolic rate, thermogenesis, carbohydrate and lipid metabolism, while its dysfunction promotes the development of metabolic disorders. In this review, we discuss the interplay between three adipokines: fatty acid binding protein type 4, fetuin-A, retinol binding protein type 4 and thyroid hormones, that shed a new light onto mechanisms underlying atherosclerosis, cardiovascular complications, obesity, insulin resistance and diabetes accompanying thyroid dysfunction. Furthermore, we summarize clinical findings on those cytokines in the course of thyroid disorders.

Effects of fetuin-A with diverse functions and multiple mechanisms on human health

Fetuin-A (Alfa 2-Heremans-Schmid) is a glycoprotein that is mainly synthesized by hepatocytes and then released into the bloodstream. While fetuin-A, a multifunctional protein, has inhibitory effects on health in the processes of calcification, mineralization, coronary artery calcification (CAC), and kidney stone formation by various mechanisms, it has such stimulatory effects as obesity, diabetes, and tumor progression processes. Fetuin-A produces these effects on the organism mainly by playing a role in the secretion levels of some inflammatory cytokines and exosomes, preventing unwanted calcification, inhibiting the autophosphorylation of tyrosine kinase, suppressing the release of adiponectin and peroxisome proliferator-activated receptor-γ (PPARγ), activating the toll-like receptor 4 (TLR-4), triggering the phosphatidylinositol 3 (PI3) kinase/Akt signaling pathway and cell proliferation, and mimicking the transforming growth factor-beta (TGF-β) receptor. In the present review, fetuin-A was examined in a wide perspective from the structure and release of fetuin-A to its effects on health.

The biology of vascular calcification

Vascular calcification (VC), characterized by different mineral deposits (i.e., carbonate apatite, whitlockite and hydroxyapatite) accumulating in blood vessels and valves, represents a relevant pathological process for the aging population and a life-threatening complication in acquired and in genetic diseases. Similarly to bone remodeling, VC is an actively regulated process in which many cells and molecules play a pivotal role. This review aims at: (i) describing the role of resident and circulating cells, of the extracellular environment and of positive and negative factors in driving the mineralization process; (ii) detailing the types of VC (i.e., intimal, medial and cardiac valve calcification); (iii) analyzing rare genetic diseases underlining the importance of altered pyrophosphate-dependent regulatory mechanisms; (iv) providing therapeutic options and perspectives.

Effects of nutritional status on serum fetuin-A level

Fetuin-A is a glycoprotein structured molecule which is mostly released by the liver. As a multifunctional protein, fetuin-A has positive effects on health such as calcification, cardiovascular diseases and tumor development processes with various mechanisms, whereas it plays a negative role in the processes of obesity, diabetes and fatty liver disease. There are a large number of studies reporting that serum fetuin-A levels are affected by several dietary factors. It is reported in some of these studies that several nutrients increase fetuin-A release, while some others have adverse effects. It is put forward that some nutrients such as dairy products, curcumin, niacin, palmitate, coffee and alcohol consumption decrease fetuin-A level, and dietary omega-3 fatty acids intake may increase fetuin-A concentration. In addition, it is indicated that high blood glucose levels increase hepatic fetuin-A release by activating extracellular signal-regulated kinase 1/2 enzymes and increased plasma free fatty acids do the same effect by increasing NF-_KB activity. Despite these studies in the literature, there is not any review evaluating fetuin-A, chronic diseases and nutrition together. Therefore, in this study, the relationship between serum fetuin levels and some diseases and the effects of nutrients on fetuin A levels were investigated with possible mechanisms.

Association between Healthy Eating Index-2010 and Fetuin-A Levels in Patients with Type 2 Diabetes: a Case-Control Study

The Healthy Eating Index-2010 (HEI-2010) assesses compliance with the 2010 Dietary Guidelines for Americans. Studies suggest that adherence to the HEI-2010 is related to lower the risk of type 2 diabetes (T2D). Fetuin-A, a novel biomarker for T2D, may play a linking role in the inverse association between HEI-2010 and T2D. Thus, a case-control analysis involving 107 patients with T2D and107 healthy subjects was conducted to determine the association between HEI-2010 and serum fetuin-A levels. The results of simple regression analysis showed that fetuin-A levels were positively associated with full name of body mass index (BMI) (p < 0.001), waist circumference (WC) (p < 0.001), fasting blood glucose (FBG) (p < 0.001), triglycerides (TG) (p = 0.003), gamma-glutamyl transferase (GGT) (p < 0.001), and homeostasis model assessment of insulin resistance (HOMA-IR) (p =0.001) and negatively associated with physical activity (PA) (p < 0.001), high-density lipoprotein (HDL) (p = 0.022), and HEI-2010 (p < 0.001) in all subjects. After controlling for confounders, the inverse association between fetuin-A and HEI-2010 remained significant in the subjects with T2D (β = -0.386; p < 0.001), 107 healthy controls (β = -0.237; p = 0.028), and all subjects (β = -0.298; p < 0.001). In conclusion, the present results suggested that higher quality diet assessed by HEI-2010 associates with lower serum fetuin-A levels in people with and without T2D. More studies are needed to confirm these findings.

Plasma Inflammation Markers of the Tumor Necrosis Factor Pathway but Not C-Reactive Protein Are Associated with Processed Meat and Unprocessed Red Meat Consumption in Bavarian Adults

BACKGROUND

High consumption of red and processed meats has been linked to higher chronic disease risk. It has been hypothesized that inflammation markers may mediate part of this association. Most previous studies on the association of red meat intake with circulating inflammation markers used C-reactive protein (CRP) but rarely other markers, and not all differentiated between processed meat and unprocessed red meat.

OBJECTIVE

We investigated the cross-sectional association of processed meat and unprocessed red meat consumption with plasma concentrations of CRP, interleukin 6 (IL-6), tumor necrosis factor (TNF)-α, soluble TNF receptor (sTNF-R) 1, and sTNF-R2 in German adults.

METHODS

Inflammation markers were quantified in the plasma of 553 adults (233 men and 320 women) aged 18-80 y within the cross-sectional Bavarian Food Consumption Survey II. Dietary intake was estimated from three 24-h dietary recalls. The association between red meat consumption and inflammation markers was analyzed with the use of multivariable-adjusted linear regression.

RESULTS

Processed meat consumption was borderline significantly associated with higher IL-6 [relative difference per 50-g increment: 5% (95% CI: -1%, 10%)] but not with CRP (2%; 95% CI: -6%, 10%), and it was inversely associated with total TNF-α (-3%; 95% CI: -6%, -1%), sTNF-R1 (-3%; 95% CI: -4%, -1%), and sTNF-R2 (-2%; 95% CI: -4%, 0%) concentrations. Unprocessed red meat consumption was not associated with CRP (-5%; 95% CI: -15%, 5%) or IL-6 (-1%; 95% CI: -9%, 7%) but was inversely associated with sTNF-R1 (-3%; 95% CI: -5%, -1%) and sTNF-R2 (-4%; 95% CI: -7%, -2%).

CONCLUSIONS

Our results suggest an inverse association between both processed meat and unprocessed red meat with inflammation markers of the TNF pathway in Bavarian adults but no association with CRP. Further research on the role of TNF pathway markers in chronic inflammation is warranted.

Pathophysiology of Non Alcoholic Fatty Liver Disease

The physiopathology of fatty liver and metabolic syndrome are influenced by diet, life style and inflammation, which have a major impact on the severity of the clinicopathologic outcome of non-alcoholic fatty liver disease. A short comprehensive review is provided on current knowledge of the pathophysiological interplay among major circulating effectors/mediators of fatty liver, such as circulating lipids, mediators released by adipose, muscle and liver tissues and pancreatic and gut hormones in relation to diet, exercise and inflammation.

Is rationale to decrease serum osteoprotegerin and fetuin-A in type 2 diabetes mellitus patients?

Fetuin-A and osteoprotegerin (OPG) are considered biomarkers of atherosclerosis, vascular calcification, inflammation in subjects with type 2 diabetes mellitus (T2DM) with possible predictive value. Recent clinical studies have been shown that fetuin-A and OPG could be helpful for cardiovascular risk stratification in T2DM. Therefore, fetuin-A and OPG may offer protection against atherosclerosis and vascular calcification. However, clinical implication of decreased serum concentrations of these biomarkers in T2DM during treatment with thiazolidinediones, in particular pioglitazone, and metformin is not fully understood. The relation of thiazolidinediones- and metformin- induced post-treatment serum levels of fetuin-A and OPG to changes in CV risk requires more investigations.