Increased renal uptake and urine excretion of oxidized LDL is possibly associated with formation of large calcium oxalate nephrolithiasis: a preliminary study

PURPOSE

Growing evidence have suggested an association between nephrolithiasis and cardiovascular disease (CVD) with unclear mechanism. Oxidized low-density lipoproteins (oxLDL) induces atherosclerosis and was found to be the possible link between these two diseases. Our study aimed to examine the serum, urine and kidney expression of oxLDL in relation to large calcium oxalate (CaOx) renal stone disease.

METHODS

A total of 67 large CaOx dominant renal stone patients and 31 stone-free controls were enrolled in the prospective case-control study. All participants were without known CVD history. Serum, urine, and kidney biopsy were collected before and during percutaneous nephrolithotomy, respectively. Enzyme-linked immunosorbent assays were used to assess serum and urine oxLDL, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and high-sensitivity C-reactive protein (hsCRP).

RESULTS

There was no significantly difference in circulating oxLDL, but serum hsCRP was significantly near two-fold higher in nephrolithiasis patients. Serum hsCRP was also correlated with stone maximal length. Urine oxLDL was significantly higher in the nephrolithiasis group and correlated with serum hsCRP and stone maximal length. Increased oxLDL uptake in kidney was found in nephrolithiasis patients, whereas no significantly renal expression of oxLDL was observed in controls.

CONCLUSIONS

The renal uptake of oxLDL with increased oxLDL excretion from large CaOx renal stone formers, independent of increased circulating oxLDL, is a novel pathological finding in kidney stone disease and brings attention to the possible involvement of renal steatosis in the process of urolithiasis formation.

Mechanism of two alkaloids isolated from coral endophytic fungus for suppressing angiogenesis in atherosclerotic plaque in HUVEC

Atherosclerosis is a significant cause of many cardiovascular diseases. Oxidized low-density lipoproteins (ox-LDL) are crucial in developing atherosclerosis. In this study, we researched the effects of two alkaloids epi-aszonalenin A (EAA) and aszonalenin (AZN) of an endophytic fungus Aspergillus terreus C23-3 from coral Pavona, on ox-LDL-induced inflammation, apoptosis and angiogenesis in HUVEC, and evaluated related factors and mechanism. The results reveal that EAA and AZN inhibit HUVEC migration, invasion, angiogenesis and reactive oxygen species (ROS) accumulation on a non-cytotoxic basis. Then, EAA and AZN suppressed the ox-LDL-induced of LOX-1, VEGF protein expression, MAPK and PI3K/AKT pathways phosphorylation. Furthermore, AZN suppressed the ox-LDL-induced inflammatory factors (IL-6, IL-1β, and TNF-α), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and VEGF receptor VEGFR-2 and platelet-derived growth factor PDGF. In addition, it inhibited ox-LDL-induced atherosclerosis by blocking inflammation and apoptosis through nuclear factor κB (NF-κB), cleaved-caspase-3 and Bax/Bcl-2 pathways. Molecular docking results confirm that the effect of AZN on atherosclerosis inhibitory activity may be attributed to hydrogen bonds formed into LOX-1 and VEGFR-2. These data indicate that EAA and AZN can effectively prevent ox-LDL-induced HUVEC damage and angiogenesis by inhibiting inflammation and apoptosis. Therefore, EAA and AZN may have potential beneficial effects in regulating atherosclerosis and plaque angiogenesis.

A Novel Peptide Isolated from Microalgae Isochrysis zhanjiangensis Exhibits Anti-apoptosis and Anti-inflammation in Ox-LDL Induced HUVEC to Improve Atherosclerosis

In the early stage, oxidized low density lipoprotein (ox-LDL) caused atherosclerosis, followed by human umbilical vein endothelial cells (HUVEC) damage, leading to a variety of cardiovascular related diseases. This study investigated the mechanism of nonapeptide (EMFGTSSET, ETT) isolated from in vitro gastrointestinal digestion of Isochrysis zhanjiang on endothelial cell inflammation and apoptosis induced by ox-LDL in atherosclerosis. At the cellular level, the results shown that ETT inhibited the up-regulation of oxidized low-density lipoprotein receptor-1 (LOX-1) induced by ox-LDL. Furthermore, ETT inhibited the fluorescence intensity of ROS, inflammatory factors (interleukin-6, interleukin-1β, and tumor necrosis factor-α) and the expression of cell adhesion molecules (vascular cell adhesion protein 1 and intercellular cell adhesion molecule-1). In addition, it also upregulates nuclear red blood cell 2 related factor 2 (Nrf2), heme oxygenase-1 (HO -1), p-Akt, and bcl-2 levels. But down-regulated the expression of p-p65, p-IκB-α, p-p38, p-ERK, p-JNK, bax, and cleaved caspase-9/-3 (c-c-9/-3), thereby inhibited ox-LDL induction inflammation and apoptosis of atherosclerosis. Through molecular docking, it was judged that the stable interaction between ETT and LOX-1 and VCAM-1 was maintained through hydrogen bonding. These results can provide a theoretical basis for ETT as a potential substance for the prevention and treatment of atherosclerosis, and further improve the value of Isochrysis zhanjiangensis.

Reduced oxidized LDL in T2D plaques is associated with a greater statin usage but not with future cardiovascular events

Background

Type 2 diabetes (T2D) patients are at a greater risk of cardiovascular events due to aggravated atherosclerosis. Oxidized LDL (oxLDL) has been shown to be increased in T2D plaques and suggested to contribute to plaque ruptures. Despite intensified statin treatment during the last decade the higher risk for events remains. Here, we explored if intensified statin treatment was associated with reduced oxLDL in T2D plaques and if oxLDL predicts cardiovascular events, to elucidate whether further plaque oxLDL reduction would be a promising therapeutic target.

Methods

Carotid plaque OxLDL levels and plasma lipoproteins were assessed in 200 patients. Plaque oxLDL was located by immunohistochemistry. Plaque cytokines, cells and scavenger receptor gene expression were quantified by Luminex, immunohistochemistry and RNA sequencing, respectively. Clinical information and events during follow-up were obtained from national registers.

Results

Plaque oxLDL levels correlated with markers of inflammatory activity, endothelial activation and plasma LDL cholesterol (r = 0.22-0.32 and p ≤ 0.01 for all). T2D individuals exhibited lower plaque levels of oxLDL, sLOX-1(a marker of endothelial activation) and plasma LDL cholesterol (p = 0.001, p = 0.006 and p = 0.009). No increased gene expression of scavenger receptors was identified in T2D plaques. The lower oxLDL content in T2D plaques was associated with a greater statin usage (p = 0.026). Supporting this, a linear regression model showed that statin treatment was the factor with the strongest association to plaque oxLDL and plasma LDL cholesterol (p < 0.001 for both). However, patients with T2D more frequently suffered from symptoms and yet plaque levels of oxLDL did not predict cardiovascular events in T2D (findings are summarized in Fig. 1a).

Conclusions

This study points out the importance of statin treatment in affecting plaque biology in T2D. It also implies that other biological components, beyond oxLDL, need to be identified and targeted to further reduce the risk of events among T2D patients receiving statin treatment.

Cameroonian professional soccer players and risk of atherosclerosis

Background

Elevated titers of antibodies against oxidized low-density lipoproteins-cholesterol (ox-LDL-Ab) have been reported among professional athletes, paradoxically reflecting an increased risk of developing atherogenic and/or cardiovascular events. This study aimed to determine titers of ox-LDL-Ab in a group of Cameroonian professional soccer players, and evaluate their evolution during part of a competition season as well as the plasmatic antioxidant status to find out if this latter correlates with ox-LDL-Ab .

Methods

We conducted a descriptive cohort study in 2012 including 18 healthy male soccer players. Three samplings were performed in March (T1), May (T2), and July 2012 (T3) to assess the lipid profile, titers of ox-LDL-Ab, and plasmatic concentrations of four antioxidants: the ferric reducing antioxidant power (FRAP), reduced glutathione (GSH), superoxide dismutase (SOD), and uric acid.

Results

Ages ranged from 16 to 28 years with a median (interquartile range) of 19.5 (19–23) years. Total cholesterol, high-density lipoproteins-cholesterol (HDL-C), low-density lipoproteins-cholesterol (LDL-C) and triglycerides varied within normal ranges throughout the three samplings. While total cholesterol and LDL-C titers increased significantly (p = 0.003 and p = 0.006, respectively), triglycerides and HDL-C values varied non-significantly throughout the measurements (p = 0.061 and p = 0.192, respectively). The median ox-LDL-Ab titers were respectively: 653.3 (468.2–838.8) mIU/ml at T1, 777.7 (553.7–1150.7) mIU/ml at T2, and 1037.7 (901.7–1481.5) mIU/ml at T3. Overall, ox-LDL-Ab titers increased significantly from T1 to T3 (p = 0.006). Concomitantly, uric acid and FRAP concentrations decreased significantly (p = 0.001 and p = 0.003, respectively); on the contrary, GSH and SOD values increased, but insignificantly (p = 0.115 and p = 0.110, respectively). There was a positive and significant correlation between ox-LDL-Ab and HDL-C (ρ = 0.519, p = 0.027), and between ox-LDL-Ab and SOD (ρ = 0.504, p = 0.033) at T2. Ox-LDL-Ab values were expected to increase with each new visit (β = 201.1; p = 0.041) and each IU/ml of SOD titers (β = 23.6; p = 0.019).

Conclusion

These Cameroonian professional soccer players exhibited high levels of ox-LDL-Ab reflecting elevated levels of oxidatively-modified LDL-C particles with an increment over time, this being insufficiently counterbalanced by the antioxidant defense mechanisms. As a consequence, they may be at increased atherogenic and cardiovascular risks.

Oxidized Low-Density Lipoprotein Predicts the Development of Renal Dysfunction in Atrial Fibrillation

BACKGROUND/AIM

To investigate the role of oxidative stress (OS) in the development of chronic kidney disease (CKD) in atrial fibrillation (AF).

METHODS

We compared OS burden, determined at study inclusion as plasma concentrations of oxidized low-density lipoprotein (oxLDL), between stable AF patients (n = 256, mean age: 62.8 ± 9.3 years; 60.9% males) with preserved renal function, defined as an estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m², and a matched control group in sinus rhythm (n = 138, mean age: 61.5 ± 11.2 years; 60.9% males). During the prospective follow-up of AF patients, we investigated the association and prognostic validity of oxLDL for CKD development, diagnosed as a sustained decline in eGFR to <60 ml/min/1.73 m².

RESULTS

AF patients had a higher mean oxLDL (76.2 ± 21.7 U/l) compared to sinus rhythm controls (61.6 ± 13.1 U/l; p < 0.001). AF presence independently predicted increased oxLDL levels in the study cohort [β = 14.7; 95% confidence interval (CI), 10.7-18.7; p < 0.001]. Over a median 4-year follow-up, 19.9% of AF patients developed CKD. Adjusting for all clinical covariates, oxLDL (per tertile) was associated with a hazard ratio of 2.17 for CKD occurrence (95% CI, 1.40-3.35; p < 0.001). AF patients in the upper oxLDL tertile (≥88.7 U/l) had a 3.70-fold (95% CI, 1.55-8.81) higher risk for CKD compared to the lower oxLDL tertile (<67.0 U/l) patients (p < 0.001). oxLDL improved discriminative validity (c-statistic increment: 0.041, 95% CI, 0.007-0.075, p = 0.017), and increased the net reclassification and integrated discrimination for CKD risk by 12.4 and 6.0%, respectively (both p < 0.001).

CONCLUSIONS

oxLDL is increased in AF patients compared to sinus rhythm controls. oxLDL has an independent association and an incremental predictive value that might complement clinical CKD risk assessment in AF patients following further research.

Physiology and pathophysiology of oxLDL uptake by vascular wall cells in atherosclerosis

Atherosclerosis is a progressive disease in which endothelial cell dysfunction, macrophage foam cell formation, and smooth muscle cell migration and proliferation, lead to the loss of vascular homeostasis. Oxidized low-density lipoprotein (oxLDL) may play a pre-eminent function in atherosclerotic lesion formation, even if their role is still debated. Several types of scavenger receptors (SRs) such as SR-AI/II, SRBI, CD36, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), toll-like receptors (TLRs) and others can promote the internalization of oxLDL. They are expressed on the surface of vascular wall cells (endothelial cells, macrophages and smooth muscle cells) and they mediate the cellular effects of oxLDL. The key influence of both oxLDL and SRs on the atherogenic process has been established in atherosclerosis-prone animals, in which antioxidant treatment and/or silencing of SRs has been shown to reduce atherogenesis. Despite some discrepancies, the indication from cohort studies that there is an association between oxLDL and cardiovascular (CV) events seems to point toward a role for oxLDL in atherosclerotic plaque progress and disruption. Finally, randomized clinical trials using antioxidants have demonstrated benefits only in high-risk patients, suggesting that additional proofs are still needed to better define the involvement of each type of modified LDL in the development of atherosclerosis.

Inflammation, lipid metabolism and cardiovascular risk in rheumatoid arthritis: A qualitative relationship?

Life expectancy in patients with rheumatoid arthritis (RA) is reduced compared to the general population owing to an increase in cardiovascular diseases (CVD) not fully explained by traditional cardiovascular risk factors. In recent years, interest has been focused on the alterations in lipid metabolism in relation to chronic inflammation as one of the possible mechanisms involved in the pathogenesis of atherosclerosis of RA patients. Research regarding this issue has revealed quantitative alterations in lipoproteins during the acute-phase reaction, and has also demonstrated structural alterations in these lipoproteins which affect their functional abilities. Although many alterations in lipid metabolism have been described in this regard, these structural changes associated with inflammation are particularly important in high-density lipoproteins as they affect their cardioprotective functions. In this respect, excessive oxidation in low-density lipoprotein (LDL) and increased lipoprotein(a) with a predominance of smaller apolipoprotein(a) isoforms has also been reported. This article will discuss proinflammatory high-density lipoproteins (piHDL), oxidized LDL and lipoprotein(a). Elevated concentrations of these lipoproteins with marked pro-atherogenic properties have been observed in RA patients, which could help to explain the increased cardiovascular risk of these patients.

Anti-oxidized low-density lipoprotein antibodies in chronic heart failure

Oxidative stress may play a significant role in the pathogenesis of heart failure (HF). Antibodies to oxidized low-density lipoprotein (oxLDL Abs) reflect an immune response to LDL over a prolonged period and may represent long-term oxidative stress in HF. The oxLDL plasma level is a useful predictor of mortality in HF patients, and measurement of the oxLDL Abs level may allow better management of those patients. Antibodies to oxLDL also significantly correlate with the New York Heart Association score. Hypercholesterolemia, smoking, hypertension, and obesity are risk factors for atherosclerotic coronary heart disease (CHD) leading to HF, but these factors account for only one-half of all cases, and understanding of the pathologic process underlying HF remains incomplete. Nutrients with antioxidant properties can reduce the susceptibility of LDL to oxidation. Antioxidant therapy may be an adjunct to lipid-lowering, angiotensin converting enzyme inhibition and metformin (in diabetes) therapy for the greatest impact on CHD and HF. Observational data suggest a protective effect of antioxidant supplementation on the incidence of HD. This review summarizes the data on oxLDL Abs as a predictor of morbidity and mortality in HF patients.