Diet-induced increase in plasma oxidized LDL promotes early fibrosis in a renal porcine auto-transplantation model

Preservation of Organs to Be Transplanted: An Essential Step in the Transplant Process

Organ transplantation remains the treatment of last resort in case of failure of a vital organ (lung, liver, heart, intestine) or non-vital organ (essentially the kidney and pancreas) for which supplementary treatments exist. It remains the best alternative both in terms of quality-of-life and life expectancy for patients and of public health expenditure. Unfortunately, organ shortage remains a widespread issue, as on average only about 25% of patients waiting for an organ are transplanted each year. This situation has led to the consideration of recent donor populations (deceased by brain death with extended criteria or deceased after circulatory arrest). These organs are sensitive to the conditions of conservation during the ischemia phase, which have an impact on the graft’s short- and long-term fate. This evolution necessitates a more adapted management of organ donation and the optimization of preservation conditions. In this general review, the different aspects of preservation will be considered. Initially done by hypothermia with the help of specific solutions, preservation is evolving with oxygenated perfusion, in hypothermia or normothermia, aiming at maintaining tissue metabolism. Preservation time is also becoming a unique evaluation window to predict organ quality, allowing repair and/or optimization of recipient choice.

Obesity and the Development of Lung Fibrosis

Obesity is an epidemic worldwide and the obese people suffer from a range of respiratory complications including fibrotic changes in the lung. The influence of obesity on the lung is multi-factorial, which is related to both mechanical injury and various inflammatory mediators produced by excessive adipose tissues, and infiltrated immune cells. Adiposity causes increased production of inflammatory mediators, for example, cytokines, chemokines, and adipokines, both locally and in the systemic circulation, thereby rendering susceptibility to respiratory diseases, and altered responses. Lung fibrosis is closely related to chronic inflammation in the lung. Current data suggest a link between lung fibrosis and diet-induced obesity, although the mechanism remains incomplete understood. This review summarizes findings on the association of lung fibrosis with obesity, highlights the role of several critical inflammatory mediators (e.g., TNF-α, TGF-β, and MCP-1) in obesity related lung fibrosis and the implication of obesity in the outcomes of idiopathic pulmonary fibrosis patients.

Astaxanthin suppresses End MT by LOX-1 pathway in ox-LDL-induced HUVECs

Introduction

Astaxanthin (ASX) is carotenoid with the highest antioxidant activity in various cell types and reverse atherosclerosis. However, the roles and detailed mechanisms of ASX in atherosclerosis associated endothelial injury remains unclear.

Methods

In vitro atherosclerosis model was established in HUVECs by incubation with oxidized low-density lipoprotein (ox-LDL). Cell viability and oxidative stress were measured. The mRNA and protein expressions of lectin-like ox-LDL receptor (LOX-1) and other related genes were determined.

Results

ox-LDL reduced cell viability of HUVECs, and induced oxidative stress, as evidenced by elevated cellular malondialdehyde (MDA) and decreased superoxide dismutase (SOD). Pretreatment with ASX (50, 100, 200, and 400 μM) markedly reversed the reduction in cell viability and an increase in migration of HUVECs induced by ox-LDL (50 μg/mL). ASX attenuated the increase in the endothelial-to-mesenchymal transition (EndMT) process, as evidenced by increased CD31 and decreased α-SMA and vimentin proteins by ASX treatment in HUVECs. Furthermore, ASX attenuated the increase in MDA and decrease in SOD induced by ox-LDL, increased supernatant NO production, attenuated the increase in iNOS and decrease in eNOS in HUVECs with ox-LDL. ASX enhanced mRNA and protein expressions of the lectin-like ox-LDL receptor (LOX-1), which was dependent on ASX’s antioxidant activity. The inhibitory effect of ASX on EndMT could be abolished by overexpression of LOX-1 in HUVECs induced by ox-LDL.

Conclusions

Our data speculate that ASX prevents ox-LDL-induced endothelial cell injury and EndMT by inducing antioxidant property (SOD and NO) and decreasing LOX-1 expression.

Oxidized LDL Is Associated with eGFR Decline in Proteinuric Diabetic Kidney Disease: A Cohort Study

Diabetic kidney disease (DKD) is a highly heterogenous disease, including the proteinuric and the nonproteinuric pattern. Oxidized low-density lipoprotein (ox-LDL) is progressively increased in DKD and causes direct damage to kidney tubular epithelial cells through a mechanism similar to that underlying the deleterious effect of lipid peroxides in the vascular endothelium. We aimed to examine the association between plasma ox-LDL cholesterol and clinical endpoints in DKD patients. Ninety-one patients with established proteinuric DKD and diabetic retinopathy were enrolled and prospectively followed for 10 years or the occurrence of death, or at least 30% decline in eGFR, or progression to end-stage kidney disease (ESKD) requiring renal replacement therapy (primary outcome). At the end of the study, both eGFR and proteinuria were reassessed. Secondary outcomes of the study were the percentage change in eGFR and proteinuria over time for each patient. At baseline, patients were divided into 2 groups according to the median ox-LDL value (i.e., below or equal and above 66.22 U/L). Both Kaplan-Meier curves (p = 0.001, log-rank test) and univariate Cox regression analysis showed that high ox-LDL was associated with the primary outcome (HR = 3.42, 95%CI = 1.55 − 7.56, p = 0.002). After adjustment for various well-known cofounders, multivariate Cox analysis showed that the association between increased circulating ox-LDL levels and the composite kidney endpoint remained significant (HR = 2.87, 95%CI = 1.14–7.20, p = 0.025). Regarding the secondary outcome of eGFR decline, the assessment of areas under the curves (AUC) showed that ox-LDL outperformed several cofounding factors (AUC 71%, 95%CI = 0.59 − 0.83, p = 0.001) and had better accuracy to predict deterioration of eGFR over time than baseline proteinuria (AUC 67%, 95%CI = 0.54 − 0.79, p = 0.014). Increased ox-LDL might be associated with disease progression in proteinuric DKD.

High-fat diet-induced aggravation of cardiovascular impairment in permethrin-treated Wistar rats

This study characterized the impact of post-weaning high-fat diet (HFD) and/or permethrin (PER) treatment on heart dysfunction and fibrosis, as well as atherogenic risk, in rats by investigating interactions between HFD and PER. Our results revealed that HFD and/or PER induced remarkable cardiotoxicity by promoting cardiac injury, biomarker leakage into the plasma and altering heart rate and electrocardiogram pattern, as well as plasma ion levels. HFD and/or PER increased plasma total cholesterol, triacylglycerols, and low-density lipoprotein (LDL) cholesterol levels but significantly reduced high-density lipoprotein (HDL) cholesterol. Cardiac content of peroxidation malonaldehyde, protein carbonyls, and reactive oxygen species were remarkably elevated, while glutathione levels and superoxide dismutase, catalase and glutathione peroxidase activities were inhibited in animals receiving a HFD and/or PER. Furthermore, cardiac DNA fragmentation and upregulation of Bax and caspase-3 gene expression supported the ability of HFD and/or PER to induce apoptosis and inflammation in rat hearts. High cardiac TGF-β1 expression explained the profibrotic effects of PER either with the standard diet or HFD. Masson's Trichrome staining clearly demonstrated that HFD and PER could cause cardiac fibrosis. Additionally, increased oxidized LDL and the presence of several lipid droplets in arterial tissues highlighted the atherogenic effects of HFD and/or PER in rats. Such PER-induced cardiac and vascular dysfunctions were aggravated by and associated with a HFD, implying that obese individuals may be more vulnerable to PER exposure. Collectively, post-weaning exposure to HFD and/or PER may promote heart failure and fibrosis, demonstrating the pleiotropic effects of exposure to environmental factors early in life.

Black raspberry (Rubus occidentalis) attenuates inflammatory markers and vascular endothelial dysfunction in Wistar rats fed a high-fat diet with fructose solution

A continuous high-fat/high-fructose diet induces inflammation and lowers vascular endothelial function in the body. This research examined the effects of black raspberry (BR) powder consumption on the inflammatory response and endothelial dysfunction in rats fed with a high-fat diet and fructose solution. Wistar rats were randomly divided into two groups as control (AIN-93G diet + distilled water) and HFF (high-fat diet + 20% fructose solution) groups, for 16 weeks. At 8 weeks, the HFF was further divided into three subgroups: HFF, HFFBR2.5 (2.5% BR in high-fat diet), and HFFBR5 (5% BR in high-fat diet). The BR-fed groups showed significantly higher high-density lipoprotein-cholesterol and lower triglycerides than the HFF group. Rats supplemented with BR showed decreased mRNA and protein expressions of inflammatory cytokines and adhesion molecules in the liver and aorta tissues. Furthermore, the aortic protein expression of endothelial nitroxide synthase was significantly greater in the HFFBR2.5 and HFFBR5 than HFF. PRACTICAL APPLICATIONS: Black raspberry (BR: Rubus occidentalis) is abundant in flavonoids and anthocyanins. BR displays various biological activities and has been used to alleviate inflammatory conditions. In our study, BR supplementation showed promising effects against high-fat/high-fructose diet-induced inflammation and endothelial dysfunction in rats by decreasing markers of inflammation and improving vascular endothelial function. These findings suggest that BR consumption could have beneficial effects on the risk factors of cardiovascular disease.

Oxidized LDL Modifies the Association between Proteinuria and Deterioration of Kidney Function in Proteinuric Diabetic Kidney Disease

Proteinuria is characterized by low accuracy for predicting onset and development of diabetic kidney disease (DKD) because it is not directly associated with molecular changes that promote DKD, but is a result of kidney damage. Oxidized low-density lipoprotein (ox-LDL) reflects oxidative stress and endothelial dysfunction, both underlying the development of proteinuria and loss of kidney function in DKD. We aimed to investigate whether ox-LDL modifies the association between proteinuria and progression of DKD in a cohort of 91 patients with proteinuric DKD and diabetic retinopathy, followed for 10 years. The primary endpoint was a combined kidney outcome of eGFR decline ≥30% or progression to end-stage kidney disease. After the end of the study, we considered the percentage change of eGFR over time as our secondary outcome. Proteinuria was associated with both outcomes, and ox-LDL amplified the magnitude of this link (p < 0.0001 for primary and p < 0.0001 for secondary outcome, respectively). After adjustment for duration of diabetes, history of cardiovascular disease and serum albumin, ox-LDL remained a significant effect modifier of the association between proteinuria and eGFR decline over time (p = 0.04). Our study shows that in proteinuric DKD, circulating ox-LDL levels amplified the magnitude of the association between proteinuria and progression of DKD.

A Novel Combination Therapy Using Rosuvastatin and Lactobacillus Combats Dextran Sodium Sulfate-Induced Colitis in High-Fat Diet-Fed Rats by Targeting the TXNIP/NLRP3 Interaction and Influencing Gut Microbiome Composition

Inflammasome targeting and controlling dysbiosis are promising therapeutic approaches to control ulcerative colitis. This report is the first to investigate the mechanisms underlying the coloprotective effects of rosuvastatin and Lactobacillus and their combined therapy on dextran sodium sulfate (DSS)-induced colitis in high-fat diet (HFD)-fed rats. Our results demonstrate the aggravation of intestinal inflammation as a consequence of an HFD following DSS administration. An association between dyslipidemia, LDL oxidation, CD36 expression, ROS generation, thioredoxin-interacting protein (TXNIP) upregulation, and NLRP3 inflammasome activation was demonstrated by DSS exposure in HFD-fed rats. We demonstrated that rosuvastatin/Lactobacillus significantly suppressed the DSS/HFD-induced increase in colon weight/length ratio, DAI, MDI, and myeloperoxidase, as well as corrected dysbiosis and improved histological characteristics. Additionally, caspase-1 activity and IL-1β-driven pyroptotic activity was significantly reduced. Rosuvastatin/Lactobacillus showed prominent anti-inflammatory effects as revealed by the IL-10/IL-12 ratio and the levels of TNF-α and IL-6. These latter effects may be attributed to the inhibition of phosphorylation-induced activation of NF-κB and a concomitant reduction in the expression of NLRP3, pro-IL-1β, and pro-IL-18. Furthermore, rosuvastatin/Lactobacillus reduced Ox-LDL-induced TXNIP and attenuated the inflammatory response by inhibiting NLRP3 inflammasome assembly. To conclude, rosuvastatin/Lactobacillus offers a safe and effective strategy for the management of ulcerative colitis.

Oxidative Stress Evaluation in Ischemia Reperfusion Models: Characteristics, Limits and Perspectives

Ischemia reperfusion injury is a complex process consisting of a seemingly chaotic but actually organized and compartmentalized shutdown of cell function, of which oxidative stress is a key component. Studying oxidative stress, which results in an imbalance between reactive oxygen species (ROS) production and antioxidant defense activity, is a multi-faceted issue, particularly considering the double function of ROS, assuming roles as physiological intracellular signals and as mediators of cellular component damage. Herein, we propose a comprehensive overview of the tools available to explore oxidative stress, particularly in the study of ischemia reperfusion. Applying chemistry as well as biology, we present the different models currently developed to study oxidative stress, spanning the vitro and the silico, discussing the advantages and the drawbacks of each set-up, including the issues relating to the use of in vitro hypoxia as a surrogate for ischemia. Having identified the limitations of historical models, we shall study new paradigms, including the use of stem cell-derived organoids, as a bridge between the in vitro and the in vivo comprising 3D intercellular interactions in vivo and versatile pathway investigations in vitro. We shall conclude this review by distancing ourselves from "wet" biology and reviewing the in silico, computer-based, mathematical modeling, and numerical simulation options: (a) molecular modeling with quantum chemistry and molecular dynamic algorithms, which facilitates the study of molecule-to-molecule interactions, and the integration of a compound in a dynamic environment (the plasma membrane...); (b) integrative systemic models, which can include many facets of complex mechanisms such as oxidative stress or ischemia reperfusion and help to formulate integrated predictions and to enhance understanding of dynamic interaction between pathways.

Pyrogallol-Phloroglucinol-6 6-Bieckol on Attenuates High-Fat Diet-Induced Hypertension by Modulating Endothelial-to-Mesenchymal Transition in the Aorta of Mice

Endothelial-to-mesenchymal transition (EndMT), which is involved in the development of various cardiovascular diseases, is induced by dyslipidemia or obesity. In dyslipidemia, the increased levels of oxidized low-density lipoproteins (oxLDL) upregulated the lectin-type oxidized LDL receptor 1 (Lox-1), which then upregulated the down signaling pathways of PKC-α/MMPs/TGF-β/SMAD2 or 3 and increased the EndMT. In this study, we investigated the effect of pyrogallol-phloroglucinol-6,6-bieckol (PPB), which is a compound of Ecklonia cava (E. cava), on decreased blood pressure (BP) by attenuating the EndMT in a high-fat diet- (HFD-) fed animal model. We also investigated PPB's attenuation effect on EndMT in oxLDL-treated mouse endothelial cells as an in vitro model. The results indicated that, in the aorta or endothelial cells of mice, the HFD or oxLDL treatment significantly increased the expression of Lox-1/PKC-α/MMP9/TGF-β/SMAD2/SMAD3. The PPB treatment significantly decreased its expression. In contrast, the HFD or oxLDL treatment significantly decreased the expression of the EC markers (PECAM-1 and vWF) while the PPB treatment significantly increased them. Moreover, the HFD or oxLDL treatment significantly increased the expression of the mesenchymal cell markers (α-SMA and vimentin) while PPB treatment significantly decreased them. PPB decreased the intima-media thickness and extracellular matrix amount of the aorta and attenuated the BP, which was increased by the HFD. In conclusion, PPB attenuated the upregulation of Lox-1/PKC-α/MMP9/TGF-β/SMAD2 and 3 and restored the EndMT in HFD-fed animals. Moreover, PPB showed a restoring effect on HFD-induced hypertension.

Mesenchymal stem cells alleviate palmitic acid-induced endothelial-to-mesenchymal transition by suppressing endoplasmic reticulum stress

High levels of plasma free fatty acids (FFAs) lead to endothelial dysfunction (ED), which is involved in the pathogenesis of metabolic syndrome, diabetes, and atherosclerosis. Endoplasmic reticulum (ER) stress and endothelial-to-mesenchymal transition (EndMT) are demonstrated to be mechanistically related to endothelial dysfunction. Mesenchymal stem cells (MSCs) have exhibited an extraordinary cytoprotective effect on cellular lipotoxicity and vasculopathy. However, the underlying mechanisms have not been clearly defined. In the present study, we investigated whether MSCs could ameliorate palmitic acid (PA)-induced endothelial lipotoxicity by reducing ER stress and EndMT. We observed that MSC cocultures substantially alleviated PA-induced lipotoxicity in human umbilical vein endothelial cells (HUVECs). MSCs were able to restore the cell viability, increase tubule formation and migration ability, and decrease inflammation response and lipid deposition. Furthermore, PA caused endothelial-to-mesenchymal transition in HUVECs, which was abrogated by MSCs possibly through inhibiting ER stress. In addition, PA stimulated MSCs to secrete more stanniocalcin-1 (STC-1). Knocking down of STC-1 in MSCs attenuated their effects on PA-induced lipotoxicity in HUVECs. In vivo, MSC transplantation alleviated dyslipidemia and endothelial dysfunction in high-fat diet-fed Sprague-Dawley rats. MSC-treated rats showed reduced expressions of ER stress-related genes in aortas and suppressed expressions of EndMT-related proteins in rat aortic endothelial cells. Overall, our findings indicated that MSCs were able to attenuate endothelial lipotoxicity through inhibiting ER stress and EndMT, in which STC-1 secreted from MSCs may play a critical role.

Interleukin-1β Promotes Ox-LDL Uptake by Human Glomerular Mesangial Cells via LOX-1

The aim of this study was to determine whether interleukin-1β (IL-1β) promotes oxidised low-density lipoprotein (Ox-LDL) uptake by human glomerular mesangial cells (HMCs) and its effect on the expression of lectin-like Ox-LDL receptor 1 (LOX-1) and to identify pathways through which IL-1β affects lipid uptake. Confocal laser scanning microscopy and flow cytometry were used to observe the effect of IL-1β on lipid uptake by HMCs and the pathway by which IL-1β may mediate lipid uptake. Real-time polymerase chain reaction (PCR) and western blotting were used to evaluate the effect of IL-1β on LOX-1 expression. Confocal laser scanning microscopy and flow cytometry revealed that IL-1β promoted uptake of fluorescent Dil-labelled Ox-LDL(Dil-Ox-LDL) by HMCs and the enhanced uptake of Dil-Ox-LDL was partially inhibited by an anti-LOX-1 antibody evaluated by flow cytometry. Further, IL-1β promoted LOX-1 mRNA and protein expression of HMCs in a dose- and time-dependent manner. Thus, Ox-LDL is ingested by HMCs under basic conditions. Inflammatory cytokine IL-1β promotes Ox-LDL uptake by HMCs. Furthermore, IL-1β promotes the mRNA and protein expression of LOX-1, a specific receptor of Ox-LDL, suggesting that the enhancement of Ox-LDL uptake may be mediated by LOX-1 pathway. Anti-LOX-1 therapy may be a promising option for treatment of glomerulosclerosis.

Hypercholesterolemia-induced increase in plasma oxidized LDL abrogated pro angiogenic response in kidney grafts

BACKGROUND

Renal transplantation is increasingly associated with the presence of comorbidity factors such as dyslipidemia which could influence the graft outcome. We hypothesized that hypercholesterolemia could affect vascular repair processes and promote post-transplant renal vascular remodeling through the over-expression of the anti-angiogenic thrombospondin-1 interacting with vascular endothelial growth factor-A levels.

METHODS

We tested this hypothesis in vitro, in vivo and in a human cohort using (1) endothelial cells; (2) kidney auto-transplanted pig subjected (n = 5) or not (n = 6) to a diet enriched in cholesterol and (3) a renal transplanted patient cohort (16 patients).

RESULTS

Cells exposed to oxidized LDL showed reduced proliferation and an increased expression of thrombospondin-1. In pigs, 3 months after transplantation of kidney grafts, we observed a deregulation of the hypoxia inducible factor 1a-vascular endothelial growth factor-A axis induced in cholesterol-enriched diet animals concomitant with an overexpression of thrombospondin-1 and a decrease in cortical microvessel density promoting vascular remodeling. In patients, hypercholesterolemia was associated with decreased vascular endothelial growth factor-A plasma levels during early follow up after renal transplantation and increased chronic graft dysfunction.

CONCLUSIONS

These results support a potential mechanism through which a high fat-diet impedes vascular repair in kidney graft and suggest the value of controlling cholesterolemia in recipient even at the early stage of renal transplantation.

Oxidized low density lipoprotein induces endothelial-to-mesenchymal transition by stabilizing Snail in human aortic endothelial cells

The endothelial-to-mesenchymal transition (EndMT) of endothelial cells contributes to the development of atherosclerosis. Oxidized low density lipoprotein (ox-LDL) is a highly risk factor for atherosclerosis. However, whether ox-LDL causes EndMT and the underlying mechanism are unclear. We report here that ox-LDL treatment is able to induce EndMT in human aortic endothelial cells (HAECs), and that the ox-LDL-induced EndMT is strictly dependent on the presence of its innate receptor, ox-LDL Receptor-1 (LOX-1). In addition, ox-LDL specifically upregulates EndMT transcriptional factor Snail, and knockdown of Snail completely attenuates ox-LDL-induced EndMT, indicating an essential role of Snail in mediating this effect. Mechanically, ox-LDL induces Snail stabilization by inhibiting its ubiquitination, which is in part attributed to inhibited GSK-3β activity. Hence, our findings suggest that inducing EndMT of aortic endothelial cells by ox-LDL might contribute to its detrimental role in promoting atherosclerosis development.

Anti-atherosclerotic effect of Cynodon dactylon extract on experimentally induced hypercholesterolemia in rats

Cynodon dactylon (Bermuda grass) is a perennial plant traditionally used as an herbal medicine in many countries. In the present study, anti-atherosclerotic property of ethanolic extract of C. dactylon was investigated in the experimentally induced hypercholesterolemia in rats. In this study, 36 male Wistar rats were selected and allocated into six groups (n = 6). The control group received a normal diet, sham group received a high cholesterol diet (HCD; 1.50% cholesterol and 24.00% fat) and other groups received a HCD and ethanolic extract of C. dactylon at low (100 mg kg^-1), moderate (200 mg kg^-1) and maximum (400 mg kg^-1) doses via gavages. The last group received atorvastatin (10 mg kg^-1) through gavage with a HCD. The study period for all groups was six months. At the end of this period, parameters including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were assessed in the blood samples. Additionally, histopathological and immunohistochemical examinations on coronary and aorta arteries sections were performed. The results showed an increase in vessels wall thickness and proliferation of smooth muscle cells in the HCD group, while these pathological changes were not seen in C. dactylon-treated groups. Treatment of HCD animals with C. dactylon positively changed lipid profile by lowering of TC, TG and LDL-C. The results indicate that C. dactylon prevents from early atherosclerotic changes in the vessels wall.

[Toward a customized preservation for each kidney graft?]

The increased number of patients in waiting list for renal transplantation requires the establishment of recommendations regarding graft preservation techniques. The preservation method impacts graft function and survival particularly in case of extended criteria donors. Based on our experience, the aim of this review is to establish a decisional diagram to draw graft management to 5years in relation to donor type and graft quality. Novel biomarkers are necessary to evaluate graft quality. Nuclear magnetic resonance or transcriptomic analyses are promising. Thus, good quality organs will be preserved in static condition associated to hypothermia; while grafts from extended criteria donors need to be assessed early during dynamic perfusion through an evaluation of perfusion solution to discriminate: good organs, with acceptable risks without perfusion conditions modifications; tolerable risk grafts for which it will be recommended to use a supplementation of perfusion solution with oxygen or pharmacologic additives such as mitochondrion protectors or oxygen carriers; and elevated risks graft which will not be used. This diagram based on experimental data needs to be assessed in clinical trials but highlights the crucial role of kidney graft quality assessment for its management and placed dynamic perfusion preservation as the protocol of choice for extended criteria donors.