Lipoprotein Metabolism and Lipid Management in Chronic Kidney Disease

The association between monocyte to high-density lipoprotein cholesterol ratio and chronic kidney disease in a Chinese adult population: a cross-sectional study

BACKGROUND

Monocyte to high-density lipoprotein cholesterol ratio (MHR) was confirmed as a novel inflammatory marker and strongly associated with the risk of several diseases. This study aimed to investigate the relationship between MHR and chronic kidney disease (CKD) in a Chinese adult population.

METHODS

In this cross-sectional study, 232,775 community-dwelling adults in Binhai who completed health checkups in 2021 were enrolled. Participants were categorized based on the MHR quartiles. Clinical characteristics of participants across different groups were compared using one-way ANOVA, Kruskal-Wallis h-test, and Chi-squared test as appropriate. Univariate and multivariable logistic regression analyses were taken to assess the relationship between MHR and the presence of CKD, as well as its association with low estimated glomerular filtration rate (eGFR) and proteinuria. Subgroup analyses were further executed to confirm the reliability of this relationship.

RESULTS

A total of 21,014 (9.0%) individuals were diagnosed with CKD. Characteristic indicators including waist circumference, body mass index (BMI), blood pressure (BP), serum uric acid (SUA), triglyceride, and fasting blood glucose (FBG) showed a gradual increase with higher MHR quartiles, whereas parameters such as age, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and eGFR decreased (p < .001). In the multivariable logistic regression analysis, we observed independent associations between MHR (per 1 SD increase) and CKD, as well as low eGFR and proteinuria, with odds ratio (ORs) and 95% confidence intervals (95%CIs) of 1.206 (1.186-1.225), 1.289 (1.260-1.319), and 1.150 (1.129-1.171), respectively (p < .001). Similar conclusions were confirmed in subgroup analysis stratified by gender, age, BMI, central obesity, hypertension, and diabetes mellitus, after justification for confounding factors.

CONCLUSION

Elevated MHR level was independently associated with the presence of CKD, suggesting that it might serve as a useful clinical tool for risk stratification, offering valuable insights to inform preventive and therapeutic approaches for clinicians in their routine medical practice.

Low Density Lipoprotein Cholesterol Decreases the Expression of Adenosine A2A Receptor and Lipid Rafts-Protein Flotillin-1: Insights on Cardiovascular Risk of Hypercholesterolemia

High blood levels of low-density lipoprotein (LDL)-cholesterol (LDL-C) are associated with atherosclerosis, mainly by promoting foam cell accumulation in vessels. As cholesterol is an essential component of cell plasma membranes and a regulator of several signaling pathways, LDL-C excess may have wider cardiovascular toxicity. We examined, in untreated hypercholesterolemia (HC) patients, selected regardless of the cause of LDL-C accumulation, and in healthy participants (HP), the expression of the adenosine A2A receptor (A2AR), an anti-inflammatory and vasodilatory protein with cholesterol-dependent modulation, and Flotillin-1, protein marker of cholesterol-enriched plasma membrane domains. Blood cardiovascular risk and inflammatory biomarkers were measured. A2AR and Flotillin-1 expression in peripheral blood mononuclear cells (PBMC) was lower in patients compared to HP and negatively correlated to LDL-C blood levels. No other differences were observed between the two groups apart from transferrin and ferritin concentrations. A2AR and Flotillin-1 proteins levels were positively correlated in the whole study population. Incubation of HP PBMCs with LDL-C caused a similar reduction in A2AR and Flotillin-1 expression. We suggest that LDL-C affects A2AR expression by impacting cholesterol-enriched membrane microdomains. Our results provide new insights into the molecular mechanisms underlying cholesterol toxicity, and may have important clinical implication for assessment and treatment of cardiovascular risk in HC.

Vitamin Supplement Use in Patients With CKD: Worth the Pill Burden?

All vitamins play essential roles in various aspects of body function and systems. Patients with chronic kidney disease (CKD), including those receiving dialysis, may be at increased risk of developing vitamin deficiencies due to anorexia, poor dietary intake, protein energy wasting, restricted diet, dialysis loss, or inadequate sun exposure for vitamin D. However, clinical manifestations of most vitamin deficiencies are usually subtle or undetected in this population. Testing for circulating levels is not undertaken for most vitamins except folate, B12, and 25-hydroxyvitamin D because assays may not be available or may be costly to perform and do not always correlate with body stores. The last systematic review through 2016 was performed for the Kidney Disease Outcome Quality Initiative (KDOQI) 2020 Nutrition Guideline update, so this article summarizes the more recent evidence. We review the use of vitamins supplementation in the CKD population. To date there have been no randomized trials to support the benefits of any vitamin supplementation for kidney, cardiovascular, or patient-centered outcomes. The decision to supplement water-soluble vitamins should be individualized, taking account the patient's dietary intake, nutritional status, risk of vitamins deficiency/insufficiency, CKD stage, comorbid status, and dialysis loss. Nutritional vitamin D deficiency should be corrected, but the supplementation dose and formulation need to be personalized, taking into consideration the degree of 25-hydroxyvitamin D deficiency, parathyroid hormone levels, CKD stage, and local formulation. Routine supplementation of vitamins A and E is not supported due to potential toxicity. Although more trial data are required to elucidate the roles of vitamin supplementation, all patients with CKD should undergo periodic assessment of dietary intake and aim to receive various vitamins through natural food sources and a healthy eating pattern that includes vitamin-dense foods.

Serum apolipoproteins (apoA-1, apoB, and apoB/apoA-1 ratio) for early identification of dyslipidemia in children with CKD

BACKGROUND

Dyslipidemia in children with chronic kidney disease (CKD) is identified based on lipid profile parameters; however, changes in lipoprotein quality precede quantitative changes.

METHODS

A cross-sectional study was done from January to October 2021; overweight, obese children, known cases of diabetes mellitus, hypothyroidism or on steroid therapy, or lipid lowering drugs were excluded. Clinical details were elicited and examinations done. Besides hemogram, kidney function tests, liver function tests, total cholesterol, low density lipoproteins (LDL), triglycerides, high density lipoproteins (HDL), and apolipoproteins A-1 and B were estimated to identify dyslipidemia. Relevant tests of significance were applied, and ROC curves were drawn for apoA-1, apoB, and apoB/apoA-1 ratios.

RESULTS

A total of 76 (61 M:15 F) children with median (IQR) age 7 (3.25-11) years were enrolled; cause of CKD was CAKUT in 82.3% patients. Dyslipidemia (alteration of 1 or more lipid parameters) was seen in 78.9% with a prevalence of 71.7% in early and 95.7% in later stages of CKD (P = 0.02); most had elevated serum triglyceride levels. The median (IQR) values of apoB, apoA-1, and apoB/apoA-1 ratio were 78 (58-110) mg/dl, 80 (63-96.75) mg/dl, and 0.88 (0.68-1.41), respectively; apoB, apoA-1, and apoB/apoA-1 ratio had a sensitivity of 26.67%, 86.67%, and 70%, respectively, and specificity of 87.5%, 62.5%, and 62.5%, respectively, for diagnosis of dyslipidemia. The ROC for apoB, apoA-1, and apoB/apoA-1 ratio showed AUC of 0.66, 0.68, and 0.74 (P = 0.4, 0.02, < 0.01), respectively.

CONCLUSIONS

The prevalence (78.9%) of dyslipidemia was high in patients with CKD especially in those with later stages. The ratio of apoB/apoA-1 was altered early and appears to be promising for early detection.

Lipid profiles and lifestyle habits of stroke survivors in the east coast region of peninsular Malaysia: Preliminary findings

Background: Stroke survivors are at high risk for recurrent cardiovascular events if no prevention strategies are undertaken. Aim: This study aimed to investigate the fasting serum lipid profiles and lifestyle habits in stroke survivors, and the factors associated with suboptimal lipid profiles. Methods: A cross-sectional retrospective study was conducted in three public hospitals in Malaysia. Stroke survivors' data regarding the socio-demographic characteristics, clinical profiles, fasting serum lipid profiles, dietary adherence, and physical activity levels were acquired. Binary logistic regression was used to examine the factors associated with suboptimal lipid goals. Results: A total of 104 stroke survivors were recruited from patients attending the neurology and rehabilitation departments. Only 22% of the stroke survivors attained the targeted low-density lipoprotein cholesterol level (LDL-C < 1.8 mmol/L). Meanwhile, more than two thirds of patients achieved the targeted total cholesterol, triglyceride, and high-density lipoprotein cholesterol goals. Patients with a longer stroke duration (Adjusted odds ratio, AOR 3.33, 95% confidence intervals, CI: 1.09, 10.13, p  =  0.034), elevated blood pressure (AOR 4.74, 95% CI: 1.65, 13.62, p  =  0.004), chronic kidney disease (AOR 3.30, 95% CI: 1.05, 10.34, p  =  0.041), abdominal obesity (AOR 3.14, 95% CI: 1.20, 8.21, p  =  0.020), excessive energy intake (AOR 2.72, 95% CI: 1.07, 6.91, p  =  0.036), and excessive saturated fatty acids intake (AOR 2.85, 95% CI: 1.02, 7.93, p  =  0.045) were significantly associated with suboptimal lipid profiles. Conclusion: The lipid goals attainment was low, particularly the LDL-C levels among Malaysian stroke survivors. Greater efforts are warranted to fully utilise the lipid-lowering therapy and the lifestyle changes in these high-risk patients.

B- and T-lymphocyte attenuator could be a new player in accelerated atherosclerosis associated with chronic kidney disease

BACKGROUND

In chronic kidney disease (CKD), cardiovascular morbi-mortality is higher than in general population. Atherosclerotic cardiovascular disease is accelerated in CKD, but specific CKD-related risk factors for atherosclerosis are unknown.

METHODS

CKD patients from the NEFRONA study were used. We performed mRNA array from blood of patients free from atheroma plaque at baseline, with (n=10) and without (n=10) de novo atherosclerotic plaque development 2 years later. Selected mRNA candidates were validated in a bigger sample (n=148). Validated candidates were investigated in vivo in an experimental model of CKD-accelerated atherosclerosis, and in vitro in murine macrophages.

RESULTS

mRNA array analysis showed 92 up-regulated and 67 down-regulated mRNAs in samples from CKD patients with de novo plaque development. The functional analysis pointed to a paramount role of the immune response. The validation in a bigger sample confirmed that B- and T-lymphocyte co-inhibitory molecule (BTLA) down-regulation was associated with de novo plaque presence after 2 years. However, BTLA down-regulation was not found to be associated with atherosclerotic progression in patients with plaque already present at baseline. In a model of CKD-accelerated atherosclerosis, mRNA and protein expression levels of BTLA were significantly decreased in blood samples and atheroma plaques. Plaques from animals with CKD were bigger, had more infiltration of inflammatory cells, higher expression of IL6 and IL17 and less presence of collagen than plaques from control animals. Incubation of macrophages with rat uremic serum decreased BTLA expression.

CONCLUSIONS

BTLA could be a potential biomarker or therapeutic target for atherosclerosis incidence in CKD patients.

Dyslipidemia in Patients with Chronic Kidney Disease: An Updated Overview

Dyslipidemia is a potentially modifiable cardiovascular risk factor. Whereas the recommendations for the treatment target of dyslipidemia in the general population are being more and more rigorous, the 2013 Kidney Disease: Improving Global Outcomes clinical practice guideline for lipid management in chronic kidney disease (CKD) presented a relatively conservative approach with respect to the indication of lipid lowering therapy and therapeutic monitoring among the patients with CKD. This may be largely attributed to the lack of high-quality evidence derived from CKD population, among whom the overall feature of dyslipidemia is considerably distinctive to that of general population. In this review article, we cover the characteristic features of dyslipidemia and impact of dyslipidemia on cardiovascular outcomes in patients with CKD. We also review the current evidence on lipid lowering therapy to modify the risk of cardiovascular events in this population. We finally discuss the association between dyslipidemia and CKD progression and the potential strategy to delay the progression of CKD in relation to lipid lowering therapy.

Association of indoor use of pesticides with CKD of unknown origin

INTRODUCTION

Chronic kidney disease (CKD) is a growing global health problem. Recently, an epidemic of CKD of unknown origin (CKDu), a form of CKD seen mostly in agricultural communities, has been emerged. One of the proposed causes of CKDu is pesticide use in farmers. On the other hand, the research on relation between indoor use of pesticides and CKDu is little. In this study, we aimed to investigate the association between indoor use of pesticide as well as the exposure time with CKDu. This study was done as part of the population-based cohort of Prospective Epidemiological Research Studies in Iran. We used the baseline data of the Zahedan Adult Cohort Study. All subjects with diabetes mellitus and/or hypertension, estimated glomerular filtration rate (eGFR) between 60-89 ml/min/1.73 m2, and unavailable creatinine measurement were excluded. Subjects with an eGFR of less than 60 ml/min/1.73 m2 were defined as having CKDu, and their data were compared with those with an eGFR of more than 90 ml/min/1.73 m2. Data regarding indoor pesticide use and duration of exposure were obtained through a questionnaire. After applying the exclusion criteria, 1079 subjects remained in the study. Female sex, single marital status, low physical activity, triglyceride (TG) levels of more than 150 mg/dl, body mass index (BMI) of more than 25 kg/m2, non-smokers, indoor pesticide use, and high pesticide exposure time were associated with CKDu. The effects of age, female sex, TG levels more than 150 mg/dl, pesticide use (OR 1.36; 95% CI 1.01-1.84), and high exposure time (third tertile of exposure time) compared to non-users (OR 1.64; 95% CI 1.07-2.51) remained significant in multivariable analysis.

CONCLUSION

We found a positive association between pesticide use, as well as longer exposure time to pesticides, and impaired kidney function in cases without diabetes mellitus and hypertension. Further longitudinal studies should be carried out to confirm these findings.

Association between remnant cholesterol and chronic kidney disease in Chinese hypertensive patients

Background

Remnant cholesterol (RC) and chronic kidney disease (CKD) have not been definitively linked in individuals with different characteristics. This study aims to investigate the relationship between serum RC level and CKD and examine possible effect modifiers in Chinese patients with hypertension.

Methods

Our study is based on the Chinese H-type Hypertension Project, which is an observational registry study conducted in real-world settings. The outcome was CKD, defined as an estimated glomerular filtration rate of less than 60 ml/min·1.73 m2. Multivariate logistic regression and smooth curve fitting were used to analyze the association between RC and CKD. Subgroup analyses were subsequently conducted to examine the effects of other variables.

Results

The mean age of the 13,024 patients with hypertension at baseline was 63.8 ± 9.4 years, and 46.8% were male. A conspicuous linear positive association was observed between RC level and CKD (per SD increment; odds ratio [OR], 1.15; 95% confidence interval [CI], 1.08-1.23). Compared with the lowest quartile group of RC, the risk of CKD was 53% higher (OR, 1.53; 95% CI, 1.26-1.86) in the highest quartile group. Furthermore, a stronger positive association between RC level and CKD was found among participants with a higher body mass index (BMI <24 vs. ≥24 kg/m2; P-interaction = 0.034) or current non-smokers (smoker vs. non-smoker; P-interaction = 0.024).

Conclusions

Among Chinese adults with hypertension, RC level was positively associated with CKD, particularly in those with a BMI of ≥24 kg/m2 and current non-smokers. These findings may help improve lipid management regimens in patients with hypertension.

Lipid Profiling Reveals Lipidomic Signatures of Weight Loss Interventions

Obesity is an epidemic all around the world. Weight loss interventions that are effective differ from each other with regard to various lipidomic responses. Here, we aimed to find lipidomic biomarkers that are related to beneficial changes in weight loss. We adopted an untargeted liquid chromatography with tandem mass spectrometry (LC-MS/MS) method to measure 953 lipid species for Exercise (exercise intervention cohort, N = 25), 1388 lipid species for LSG (laparoscopic sleeve gastrectomy cohort, N = 36), and 886 lipid species for Cushing (surgical removal of the ACTH-secreting pituitary adenomas cohort, N = 25). Overall, the total diacylglycerol (DG), triacylglycerol (TG), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and sphingomyelin (SM) levels were associated with changes in BMI, glycated hemoglobin (HbA1c), triglyceride, and total cholesterol according to weight loss interventions. We found that 73 lipid species changed among the three weight loss interventions. We screened 13 lipid species with better predictive accuracy in diagnosing weight loss situations in either Exercise, LSG, or Cushing cohorts (AUROC > 0.7). More importantly, we identified three phosphatidylcholine (PC) lipid species, PC (14:0_18:3), PC (31:1), and PC (32:2) that were significantly associated with weight change in three studies. Our results highlight potential lipidomic biomarkers that, in the future, could be used in personalized approaches involving weight loss interventions.

Development of a risk prediction score and equation for chronic kidney disease: a retrospective cohort study

Chronic kidney disease (CKD) is a risk factor for end-stage renal disease and contributes to increased risk of cardiovascular disease morbidity and mortality. We aimed to develop a risk prediction score and equation for future CKD using health checkup data. This study included 58,423 Japanese participants aged 30-69 years, who were randomly assigned to derivation and validation cohorts at a ratio of 2:1. The predictors were anthropometric indices, life style, and blood sampling data. In derivation cohort, we performed multivariable logistic regression analysis and obtained the standardized beta coefficient of each factor that was significantly associated with new-onset CKD and assigned scores to each factor. We created a score and an equation to predict CKD after 5 years and applied them to validation cohort to assess their reproducibility. The risk score ranged 0-16, consisting of age, sex, hypertension, dyslipidemia, diabetes, hyperuricemia, and estimated glomerular filtration rate (eGFR), with area under the curve (AUC) of 0.78 for the derivation cohort and 0.79 for the validation cohort. The CKD incidence gradually and constantly increased as the score increased from ≤ 6 to ≥ 14. The equation consisted of the seven indices described above, with AUC of 0.88 for the derivation cohort and 0.89 for the validation cohort. We developed a risk score and equation to predict CKD incidence after 5 years in Japanese population under 70 years of age. These models had reasonably high predictivity, and their reproducibility was confirmed through internal validation.

Rapid Molecular Evaluation of Human Kidney Tissue Sections by In Situ Mass Spectrometry and Machine Learning to Classify the Nephrotic Syndrome

Nephrotic syndrome (NS) is classified based on morphological changes of glomeruli in biopsied kidney tissues evaluated by time-consuming microscopy methods. In contrast, we employed desorption electrospray ionization mass spectrometry (DESI-MS) directly on renal biopsy specimens obtained from 37 NS patients to rapidly differentiate lipid profiles of three prevalent forms of NS: IgA nephropathy (n = 9), membranous glomerulonephritis (n = 7), and lupus nephritis (n = 8), along with other types of glomerular diseases (n = 13). As we noted molecular heterogeneity in regularly spaced renal tissue regions, multiple sections from each biopsy specimen were collected, providing a total of 973 samples for investigation. Using multivariate analysis, we report differential expressions of glycerophospholipids, sphingolipids, and glycerolipids among the above four classes of NS kidneys, which were otherwise overlooked in several past studies correlating lipid abnormalities with glomerular diseases. We developed machine learning (ML) models with the top 100 features using the support vector machine, which enabled us to discriminate the concerned glomerular diseases with 100% overall accuracy in the training, validation, and holdout test set. This DESI-MS/ML-based tissue analysis can be completed in a few minutes, in sharp contrast to a daylong procedure followed in the conventional histopathology of NS.

KLKB1 and CLSTN2 are associated with HDL-mediated cholesterol efflux capacity in a genome-wide association study

BACKGROUND AND AIMS

HDL-mediated cholesterol efflux capacity (CEC) may protect from cardiovascular disease. Thus, we aimed to identify its genetic and non-genetic determinants.

METHODS

We measured CEC to 2% apolipoprotein B-depleted serum using BODIPY-cholesterol and cAMP-stimulated J774A.1 macrophages using serum samples from 4,981 participants in the German Chronic Kidney Disease (GCKD) study. Variance of CEC explained by clinical and biochemical parameters in a multivariable linear regression model was calculated by proportional marginal variance decomposition. A genome-wide association study with 7,746,917 variants was performed based on an additive genetic model. The main model was adjusted for age, sex and principal components 1-10. Further models were selected for sensitivity analysis and to reduce residual variance by known CEC pathways.

RESULTS

Variables that explained 1% and more of the variance of CEC were concentrations of triglycerides (12.9%), HDL-cholesterol (11.8%), LDL-cholesterol (3.0%), apolipoprotein A-IV (2.8%), PCSK9 (1.0%), and eGFR (1.0%). The KLKB1 (chr4) and APOE/C1 (chr19) loci were genome-wide significantly (p < 5x10-8) associated with CEC in our main model (p = 8.8x10-10 and p = 3.3x10-10, respectively). KLKB1 remained significantly associated after additional adjustment for either kidney parameters, HDL-cholesterol, triglycerides or apolipoprotein A-IV concentrations, while the APOE/C1 locus was not significantly associated anymore after adjustment for triglycerides. Adjustment for triglycerides also revealed an association with the CLSTN2 locus (chr3; p = 6.0x10-9).

CONCLUSIONS

We identified HDL-cholesterol and triglycerides as the main determinants of CEC. Furthermore, we newly found a significant association of CEC with the KLKB1 and the CLSTN2 locus and confirmed the association with the APOE/C1 locus, likely mediated by triglycerides.

Use of fibrates is not associated with reduced risks of mortality or cardiovascular events among ESRD patients: A national cohort study

Background

Although a recent study reported that fibrates are associated with a low risk of cardiovascular (CV) death and can postpone the need for long-term hemodialysis in patients with advanced chronic kidney disease (CKD), little is known regarding whether the CV protective effects of fibrates extend to patients with end-stage renal disease (ESRD). The present study compared CV outcomes and mortality among patients with ESRD treated with fibrates, statins, neither, or their combination.

Methods

This cohort study extracted data from Taiwan's National Health Insurance Research Database (NHIRD). Adult patients with ESRD and hyperlipidemia were identified and categorized into four groups (fibrate, statin, combination, and non-user groups) according to their use of different lipid-lowering therapies within 3 months prior to the commencement of permanent dialysis. Inverse probability of treatment weighting was used to balance the baseline characteristics of the groups. The follow-up outcomes were all-cause mortality, CV death, and major adverse cardiac and cerebrovascular events (MACCEs).

Results

Compared with the non-user and statin groups, the fibrate group did not exhibit significantly lower risks of all-cause mortality [fibrate vs. non-user: hazard ratio (HR), 0.97; 95% confidence interval (CI), 0.92–1.03; statin vs. fibrate: HR, 0.95; 95% CI, 0.90–1.01], CV death (fibrate vs. non-user: HR, 0.97; 95% CI, 0.90–1.05; statin vs. fibrate: HR, 0.97; 95% CI, 0.90–1.06), and MACCEs (fibrate vs. non-user: HR, 1.03; 95% CI, 0.96–1.10; statin vs. fibrate: HR, 0.94; 95% CI, 0.87–1.004). The combination of fibrates and statins (specifically moderate- to high-potency statins) did not result in lower risks of all-cause mortality, CV death, or MACCEs compared with statins alone.

Conclusion

In patients with ESRD, the use of fibrates might be not associated with reduced mortality or CV risks, regardless of whether they are used alone or in combination with statins.

Arctic introgression and chromatin regulation facilitated rapid Qinghai-Tibet Plateau colonization by an avian predator

The Qinghai-Tibet Plateau (QTP), possesses a climate as cold as that of the Arctic, and also presents uniquely low oxygen concentrations and intense ultraviolet (UV) radiation. QTP animals have adapted to these extreme conditions, but whether they obtained genetic variations from the Arctic during cold adaptation, and how genomic mutations in non-coding regions regulate gene expression under hypoxia and intense UV environment, remain largely unknown. Here, we assemble a high-quality saker falcon genome and resequence populations across Eurasia. We identify female-biased hybridization with Arctic gyrfalcons in the last glacial maximum, that endowed eastern sakers with alleles conveying larger body size and changes in fat metabolism, predisposing their QTP cold adaptation. We discover that QTP hypoxia and UV adaptations mainly involve independent changes in non-coding genomic variants. Our study highlights key roles of gene flow from Arctic relatives during QTP hypothermia adaptation, and cis-regulatory elements during hypoxic response and UV protection.

Non-High-Density Lipoprotein Cholesterol and Cardiovascular Outcomes in Chronic Kidney Disease: Results from KNOW-CKD Study

As non-high-density lipoprotein cholesterol (non-HDL-C) levels account for all atherogenic lipoproteins, serum non-HDL-C level has been suggested to be a marker for cardiovascular (CV) risk stratification. Therefore, to unveil the association of serum non-HDL-C levels with CV outcomes in patients with non-dialysis chronic kidney disease (ND-CKD), the patients at stages 1 to 5 (n = 2152) from the Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease (KNOW-CKD) were prospectively analyzed. The subjects were divided into quintiles by serum non-HDL-C level. The primary outcome was a composite of all-cause death or non-fatal CV events. The median duration of follow-up was 6.940 years. The analysis using the Cox proportional hazard model unveiled that the composite CV event was significantly increased in the 5th quintile (adjusted hazard ratio 2.162, 95% confidence interval 1.174 to 3.981), compared to that of the 3rd quintile. A fully adjusted cubic spline model depicted a non-linear, J-shaped association between non-HDL-C and the risk of a composite CV event. The association remained robust in a series of sensitivity analyses, including the analysis of a cause-specific hazard model. Subgroup analyses reveled that the association is not significantly altered by clinical conditions, including age, gender, body mass index, estimated glomerular filtration rate, and albuminuria. In conclusion, high serum non-HDL-C level increased the risk of adverse CV outcomes among the patients with ND-CKD. Further studies are warranted to define the optimal target range of non-HDL-C levels in this population.

Activation of the Nrf2/ARE signaling pathway protects against palmitic acid-induced renal tubular epithelial cell injury by ameliorating mitochondrial reactive oxygen species-mediated mitochondrial dysfunction

Chronic kidney disease (CKD) is often accompanied by dyslipidemia, and abnormal lipid metabolism in proximal tubule cells is considered closely related to the dysfunction of proximal tubule cells and eventually leads to accelerated kidney damage. Nuclear factor E2-related factor 2 (Nrf2), known as a redox-sensitive transcription factor, is responsible for regulating cellular redox homeostasis. However, the exact role of Nrf2 in dyslipidemia-induced dysfunction of proximal tubule cells is still not fully elucidated. In the present study, we showed that palmitic acid (PA) induced mitochondrial damage, excessive mitochondrial reactive oxygen species (ROS) (mtROS) generation, and cell injury in HK-2 cells. We further found that mtROS generation was involved in PA-induced mitochondrial dysfunction, cytoskeletal damage, and cell apoptosis in HK-2 cells. In addition, we demonstrated that the Nrf2/ARE signaling pathway was activated in PA-induced HK-2 cells and that silencing Nrf2 dramatically aggravated PA-induced mtROS production, mitochondrial damage, cytoskeletal damage and cell apoptosis in HK-2 cells. However, the mitochondrial antioxidant MitoTEMPOL effectively eliminated these negative effects of Nrf2 silencing in HK-2 cells under PA stimulation. Moreover, activation of the Nrf2/ARE signaling pathway with tBHQ attenuated renal injury, significantly reduced mtROS generation, and improved mitochondrial function in rats with HFD-induced obesity. Taken together, these results suggest that the Nrf2/ARE-mediated antioxidant response plays a protective role in hyperlipidemia-induced renal injury by ameliorating mtROS-mediated mitochondrial dysfunction and that enhancing Nrf2 antioxidant signaling provides a potential therapeutic strategy for kidney injury in CKD with hyperlipidemia.

Relationship between Renal Function, Fibrin Clot Properties and Lipoproteins in Anticoagulated Patients with Atrial Fibrillation

Background: Mechanisms by which chronic kidney disease (CKD) influences fibrin clot properties in atrial fibrillation (AF) remain ill-defined. We aimed to investigate the effects of AF and CKD on fibrin clot properties and lipoproteins, and determine the relationship between these factors. Methods: Prospective cross-sectional study of patients recruited from cardiology services in Liverpool between September 2019 and October 2021. Primary groups consisted of anticoagulated AF patients with and without CKD in a 1:1 ratio. Control group comprised anticoagulated patients without AF or CKD. Fibrin clot properties were analysed using turbidity and permeation assays. Detailed lipoprotein characteristics, including total cholesterol, low-density lipoprotein cholesterol (LDL-C), small dense LDL and oxidised LDL, were measured. Results: Fifty-six anticoagulated patients were enrolled (median age 72.5; 34% female); 46 with AF (23 with CKD and 23 without CKD) and 10 controls. AF was associated with changes in three indices of fibrin clot properties using PTT (Tlag 314 vs. 358 s, p = 0.047; Abspeak 0.153 vs. 0.111 units, p = 0.031; Tlysis50% 884 vs. 280 s, p = 0.047) and thrombin reagents (Tlag 170 vs. 132 s, p = 0.031; Tmax 590 vs. 462 s, p = 0.047; Tpeak50% 406 vs. 220 s, p = 0.005) while the concomitant presence of CKD led to changes in fibrin clot properties using kaolin (Tlag 1072 vs. 1640 s, p = 0.003; Tmax 1458 vs. 1962 s, p = 0.005; Tpeak50% 1294 vs. 2046, p = 0.008) and PPP reagents (Tlag 566 vs. 748 s, p = 0.044). Neither of these conditions were associated with changes in fibrin clot permeability. Deteriorating eGFR was significantly correlated to the speed of clot formation, and CKD was independently associated with unfavourable clot properties (Tlag −778, p = 0.002; Tmax −867, p = 0.004; Tpeak50% −853, p = 0.004 with kaolin reagent). AF alone was not associated with changes in lipoprotein distribution while AF patients with CKD had lower total cholesterol, LDL-C and small dense LDL due to the presence of other risk factors. No significant relationship was observed between fibrin clot properties and lipoprotein distribution. Conclusions: There are important changes that occur in fibrin clot properties with AF and CKD that may account for the increased risk of thromboembolic complications. However, these changes in fibrin clot properties were not attributable to alterations in lipoprotein distribution.

Hypertriglyceridemia in Preterm Infants

Preterm and critically ill infants are at risk for hypertriglyceridemia (HTG). Common risk factors for HTG include prematurity, intravenous lipid emulsion dose and oil composition, reduced lipoprotein lipase activity, fetal growth restriction, sepsis, and renal failure. Despite these risk factors, clinicians lack a universally agreed upon definition for HTG and evidence-based approach to HTG management. This review provides a detailed overview of triglyceride and intravenous lipid emulsion metabolism and how this relates to specific HTG risk factors, along with some practical considerations for managing HTG in the neonatal population.

In vivo Trial of Bifidobacterium longum Revealed the Complex Network Correlations Between Gut Microbiota and Health Promotional Effects

Complete genome sequence analysis of Bifidobacterium longum subsp. longum BCBL-583 isolated from a Korean female fecal sample showed no virulence factor or antibiotic resistance gene, suggesting human safety. In addition, this strain has oxygen and heat tolerance genes for food processing, and cholesterol reduction and mucin adhesion-related genes were also found. For in vivo evaluations, a high fat diet (HFD) mouse model was used, showing that BCBL-583 administration to the model (HFD-583) reduced the total cholesterol and LDL-cholesterol in the blood and decreased pro-inflammatory cytokines but increased anti-inflammatory cytokines, substantiating its cholesterol reduction and anti-inflammation activities. Subsequent microbiome analysis of the fecal samples from the HFD mouse model revealed that BCBL-583 administration changed the composition of gut microbiota. After 9 weeks feeding of bifidobacteria, Firmicutes, Actinobacteria, and Bacteroidetes increased, but Proteobacteria maintained in the HFD mouse models. Further comparative species-level compositional analysis revealed the inhibitions of cholesterol reduction-related Eubacterium coprostanoligenes and obesity-related Lactococcus by the supplementation of B. longum BCBL-583, suggesting its possible cholesterol reduction and anti-obesity activities. The correlation analysis of HFD-583 between the gut microbiota compositional change and cholesterol/immune response showed that Verrucomicrobia, Firmicutes, Actinobacteria, and Bacteroidetes may play an important role in cholesterol reduction and anti-inflammation. However, correlation analysis of Proteobacteria showed the reverse correlation in HFD-583. Interestingly, the correlation analysis of B. longum ATCC 15707 administration to HFD model showed similar patterns of cholesterol but different in immune response patterns. Therefore, this correlation analysis suggests that the microbial composition and inflammatory cytokine/total-cholesterol may be closely related in the administration of BCBL-583 in the HFD mice group. Consequently, BCBL-583 could be a good probiotic strain for gut health promotion through gut microbiota modulation.

The Role of Phytosterols in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease is now recognized as the most common cause of chronic liver disease with an increasing prevalence in both adults and children. Although the symptoms are absent or poorly expressed in most cases, some patients may progress to end-stage liver disease. The pathogenesis of NAFLD is known to be multifactorial. Current therapeutic recommendations focus on lifestyle changes in order to reduce the incidence of risk factors and drugs targeting major molecular pathways potentially involved in the development of this disease. Given that a pharmacological treatment, completely safe and effective, is not currently known in recent years more research has been done on the effects that some bio-active natural compounds, derived from plants, have in preventing the onset and progression of NAFLD. Numerous studies, in animals and humans, have shown that phytosterols (PSs) play an important role in this pathology. Phytosterols are natural products that are found naturally in plant. More than 250 phytosterols have been identified, but the most common in the diet are stigmasterol, β-sitosterol, and campesterol. Consumption of dietary PSs can reduce serum cholesterol levels. Due to these properties, most studies have focused on their action on lipid metabolism and the evolution of NAFLD. PSs may reduce steatosis, cytotoxicity oxidative stress, inflammation, and apoptosis. The purpose of this review is to provide an overview of the importance of dietary phytosterols, which are a window of opportunity in the therapeutic management of NAFLD.

The Roles of Fatty Acids and Apolipoproteins in the Kidneys

The kidneys are organs that require energy from the metabolism of fatty acids and glucose; several studies have shown that the kidneys are metabolically active tissues with an estimated energy requirement similar to that of the heart. The kidneys may regulate the normal and pathological function of circulating lipids in the body, and their glomerular filtration barrier prevents large molecules or large lipoprotein particles from being filtered into pre-urine. Given the permeable nature of the kidneys, renal lipid metabolism plays an important role in affecting the rest of the body and the kidneys. Lipid metabolism in the kidneys is important because of the exchange of free fatty acids and apolipoproteins from the peripheral circulation. Apolipoproteins have important roles in the transport and metabolism of lipids within the glomeruli and renal tubules. Indeed, evidence indicates that apolipoproteins have multiple functions in regulating lipid import, transport, synthesis, storage, oxidation and export, and they are important for normal physiological function. Apolipoproteins are also risk factors for several renal diseases; for example, apolipoprotein L polymorphisms induce kidney diseases. Furthermore, renal apolipoprotein gene expression is substantially regulated under various physiological and disease conditions. This review is aimed at describing recent clinical and basic studies on the major roles and functions of apolipoproteins in the kidneys.

The association between diabetes coexisting with low levels of high-density lipoprotein cholesterol and peritoneal dialysis-related peritonitis

BACKGROUND

Low levels of high-density lipoprotein cholesterol (HDL-C) and diabetes are common in patients undergoing peritoneal dialysis (PD). The aim of this study was to investigate the association between the coexistence of diabetes with a low level of HDL-C and the first episode of peritoneal dialysis-related peritonitis (PDRP) in patients with PD.

METHODS

We retrospectively investigated patients with PD from January 1, 2003, to May 31, 2020, in four PD centers. Patients with PD were divided into four groups: no comorbidities, low HDL-C only, diabetes only, and diabetes plus low HDL-C. The clinical and laboratory baseline data of the four groups were collected and compared. The association between diabetes coexisting with low HDL-C levels and the first episode of PDRP was analyzed by multivariate Cox regression analysis.

RESULTS

A total of 1013 patients with PD were included in our study. The mean age was 49.94 ± 14.32 years, and 597 (58.99%) patients were males. A total of 301 (29.7%) patients had their first episodes of PDRP, and low HDL-C levels coexisted with diabetes in 72 patients with PD. After adjusting for confounding factors, a low level of HDL-C coexisting with diabetes was significantly associated with the first episode of PDRP in our study (hazard ratio: 2.81, 95% CI 1.32 ~ 4.73, p = 0.005). The associations among HDL-C, diabetes and PDRP were consistent in the following subgroups: sex, age, and pre-existing CVD (all P interaction > 0.05).

CONCLUSIONS

Patients with both diabetes and low HDL-C levels were at higher risk for PDRP in patients with PD.

PCSK9 and Cardiovascular Disease in Individuals with Moderately Decreased Kidney Function

Background and objectives: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of lipid homeostasis. Studies investigating the association between PCSK9 and cardiovascular disease in large cohorts of CKD patients are limited. Design, setting, participants, and measurements: The association of PCSK9 concentrations with prevalent and incident cardiovascular disease was investigated in 5,138 Caucasians of the German Chronic Kidney Disease study with a median follow-up of 6.5 years. Inclusion criteria were eGFR of 30-60 mL/min/1.73 m² or an eGFR>60 mL/min/1.73m² in the presence of overt proteinuria (urine albumin-creatinine ratio >300mg/g or equivalent). Prevalent cardiovascular disease was defined as history of non-fatal myocardial infarction, coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, carotid arteries interventions and stroke. Incident major adverse cardiovascular disease events included death from cardiovascular causes, acute non-fatal myocardial infarction and non-fatal stroke. Results: Median PCSK9 concentration in the cohort was 285 ng/mL (interquartile range 231-346 ng/mL). There was no association between PCSK9 concentrations and baseline eGFR and albuminuria. With each 100 ng/ml increment of PCSK9, the odds for prevalent cardiovascular disease (n=1,284) was 1.22-fold (95%CI 1.12-1.34, p<0.001) higher in a model with extended adjustment for major confounders. This association was stronger in non-statin than statin-users (p-value for interaction=0.009). During follow-up 474 individuals experienced a major adverse cardiovascular disease event and participants in PCSK9 quartiles 2 to 4 had a 32%-47% higher risk compared to quartile 1 (p<0.05). Subgroup analysis revealed this association was restricted to those participants who already had cardiovascular disease at baseline (all HR>1.75, p<0.05). In addition, PCSK9 showed a valuable gain in classification accuracy both for prevalent cardiovascular disease (NRI=0.27, 95%CI:0.20-0.33) and incident major adverse cardiovascular disease events during follow-up (NRI=0.10, 95%CI:0.008-0.21) when added to an extended adjustment model. Conclusions: Our findings reveal no relation of PCSK9 with baseline eGFR and albuminuria, but a significant association between higher PCSK9 concentrations and risk of cardiovascular disease independent of traditional risk factors including LDL-cholesterol levels.

Control of Cholesterol Metabolism Using a Systems Approach

Simple Summary

Cholesterol is the main sterol in mammals that is essential for healthy cell functionining. It plays a key role in metabolic regulation and signaling, it is a precursor molecule of bile acids, oxysterols, and all steroid hormones. It also contributes to the structural makeup of the membranes. Its homeostasis is tightly controlled since it can harm the body if it is allowed to reach abnormal blood concentrations. One of the diseases associated with elevated cholesterol levels being the major cause of morbidities and mortalities worldwide, is atherosclerosis. In this study, we have developed a model of the cholesterol metabolism taking into account local inflammation and oxidative stress. The aim was to investigate the impact of the interplay of those processes and cholesterol metabolism disturbances on the atherosclerosis development and progression. We have also analyzed the effect of combining different classes of drugs targeting selected components of cholesterol metabolism.

Abstract

Cholesterol is an essential component of mammalian cells and is involved in many fundamental physiological processes; hence, its homeostasis in the body is tightly controlled, and any disturbance has serious consequences. Disruption of the cellular metabolism of cholesterol, accompanied by inflammation and oxidative stress, promotes the formation of atherosclerotic plaques and, consequently, is one of the leading causes of death in the Western world. Therefore, new drugs to regulate disturbed cholesterol metabolism are used and developed, which help to control cholesterol homeostasis but still do not entirely cure atherosclerosis. In this study, a Petri net-based model of human cholesterol metabolism affected by a local inflammation and oxidative stress, has been created and analyzed. The use of knockout of selected pathways allowed us to observe and study the effect of various combinations of commonly used drugs on atherosclerosis. The analysis results led to the conclusion that combination therapy, targeting multiple pathways, may be a fundamental concept in the development of more effective strategies for the treatment and prevention of atherosclerosis.

Blood Plasma Metabolites in Diabetes-Associated Chronic Kidney Disease: A Focus on Lipid Profiles and Cardiovascular Risk

Background

We investigated a cross-sectional metabolomic analysis of plasma and urine of patients with early and late stage diabetes associated chronic kidney disease (CKD), inclusive of stages 1–5 CKD, to identify potential metabolomic profiles between the two groups.

Methods

This cross-sectional study recruited 119 adults. Metabolomic biomarkers were quantified in 119 non-fasted plasma and 57 urine samples using a high-throughput proton Nuclear Magnetic Resonance platform. Analyses were conducted using R with the ggforestplot package. Linear regression models were minimally adjusted for age, sex, and body mass index and p-values were adjusted for multiple comparisons using the Benjamini-Hockberg method with a false discovery rate of 0.05.

Results

Apolipoprotein A1 concentration (ApoA1) was reduced (adj. p = 0.04) and apolipoprotein B/apolipoprotein A1 ratio (ApoB/ApoA1) was increased (adj. p = 0.04) in late CKD compared with early CKD. Low-density lipoprotein triglyceride (LDL-TG) had an increased concentration (adj. p = 0.01), while concentrations of high-density lipoprotein cholesterol (HDL-C) were reduced (adj. p = 0.04) in late CKD compared to early stages of disease.

Conclusion

Our results highlight the presence of abnormal lipid metabolism namely significant reduction in the protective ApoA1 and significant increase in atherogenic ApoB/ApoA1 ratio. The study also demonstrates significantly elevated levels of triglyceride-rich lipoproteins such as LDL-TG. We illustrate the significant reduction in protective HDL-C in individuals with diabetic CKD. It explores a detailed plasma lipid profile that significantly differentiates between the late and early CKD groups as well as each CKD stage. The study of complex metabolite profiles may provide additional data required to enable more specific cardiovascular risk stratification.

MIF rs755622 and IL6 rs1800795 Are Implied in Genetic Susceptibility to End-Stage Renal Disease (ESRD)

Chronic kidney disease (CKD) is characterized by an increased risk of kidney failure and end-stage renal disease (ESRD). Aging and comorbidities as cardiovascular diseases, metabolic disorders, infectious diseases, or tumors, might increase the risk of dialysis. In addition, genetic susceptibility factors might modulate kidney damage evolution. We have analyzed, in a group of ESRD patients and matched controls, a set of SNPs of genes (Klotho rs577912, rs564481, rs9536314; FGF23 rs7955866; IGF1 rs35767; TNFA rs1800629; IL6 rs1800795; MIF rs755622, rs1007888) chosen in relation to their possible involvement with renal disease and concomitant pathologies. Analysis of the raw data did indicate that IL6 rs180795 and MIF rs755622 SNPs might be markers of genetic susceptibility to ESRD. In particular, the C positive genotypes of MIF rs755622, (dominant model) seem to be an independent risk factor for ESDR patients (data adjusted for age, gender, and associated pathologies). Stratifying results according to age MIF rs755622 C positive genotype frequencies are increased in both the two age classes considered (<59 and ≥59-year-old subjects). Analyses of data according to gender allowed us to observe that ESRD women shoved a significantly reduced frequency of genotypes bearing IL6 rs180795 C allele. In addition, MIF rs755622 might interact with diabetes or hypercholesterolemia in increasing susceptibility to ESRD. In conclusion, our data indicate that some polymorphisms involved in the regulation of both renal function and inflammatory response can influence the evolution of chronic kidney disease and suggest that the modulation of the activities of these and other genes should also be considered as therapeutic targets on to intervene with innovative therapies.

Reverse epidemiology for lipid disorders in hemodialysis-dependent patients: Role of dilutional hypolipidemia

Introduction:

Atherosclerotic cardiovascular disease is a major cause of mortality and morbidity in dialysis patients. Compared to general population, dialysis patients have lower lipid levels and higher vascular events. This paradox is popularly known as reverse epidemiology. Present study is an attempt to understand reasons for low lipids in dialysis patients.

Subjects and Methods:

This was a prospective observational multicentric study involving three stages across six dialysis units with Care Hospitals, Hyderabad. Maintenance hemodialysis patients were studied with fasting lipid profiles [TC, LDL-c, HDL-c, and TG], pre- and post-dialysis blood lipids and effluent water lipid profiles. Other parameters studied were use of statins, interdialytic weight gain, and ultrafiltration. All patients had uniform dialysis protocols regarding filter used and dialysis duration.

Results:

Of the 91 patients studied, we observed significant rise in post-dialysis TC, LDL, and HDL [P < 0.01] and lower lipids [P < 0.01] just before the next dialysis. Lipids were least filtered across the membrane except HDL, which was found in effluent water for more than 60% of patients. Single use of dialyser was associated with higher rise in post dialysis lipids as well as HDL getting filtered in effluent [P = 0.24]. Rosuvastatin was associated with lower lipid values [P = 0.08] and BMI [P = 0.19].

Conclusions:

Low lipid levels in dialysis patients are due to dilutional hypolipidemia and needs correction with an equation proposed in present study. Corrected lipids should be used for risk stratification and deploying treatment.

Egyptian practical guidance in hypertriglyceridemia management 2021

Hypertriglyceridemia (HTG) is a very common, yet underappreciated problem in clinical practice. Elevated triglyceride (TG) levels are independently associated with atherosclerotic cardiovascular disease (ASCVD) risk. Furthermore, severe HTG may lead to acute pancreatitis. Although LDL-guided statin therapy has improved ASCVD outcomes, residual risk remains. Recent trials have demonstrated that management of high TG levels, in patients already on statin therapy, reduces the rate of major vascular events. Few guidelines were issued, providing important recommendations for HTG management strategies. The goal of treatment is to reduce the risk of ASCVD and acute pancreatitis. The management stands on lifestyle modification, detection of secondary causes of HTG and pharmacological therapy, when indicated. In this guidance we review the causes and classification of HTG and summarize the current methods for risk estimation, diagnosis and treatment. The present guidance provides a focused update on the management of HTG, outlined in a simple user-friendly format, with an emphasis on the latest available data.

Estimation of LDL cholesterol in chronic kidney disease

AIMS 

Most of the laboratories make use of the Friedewald formula to assess low-density lipoprotein cholesterol (LDL-C). The accuracy of this approach, however, crucially depends on triglyceride concentrations. Since hypertriglyceridaemia is a characteristic trait of the lipid profile in chronic kidney disease (CKD), the present study examines the accuracy of the Friedewald formula in this population. It aims to derive and validate a more accurate equation for CKD.

METHODS 

Cross-sectional study on two cohorts of subjects (overall n = 3.514) with estimated glomerular filtration rate (eGFR) <60 mL/min comparing directly measured LDL-C (LDL-Cmeas) as assessed by an enzymatic assay (Roche, Switzerland) to concentrations estimated by the Friedewald (LDL-CF) and the Martin's formula (LDL-CM). Accuracy was analysed by Bland-Altman and linear regression analyses. In the first cohort, a novel formula was derived to assess LDL-C in CKD. The formula was validated in Cohort 2.

RESULTS 

Cohort 1 comprised 1738 subjects, and Cohort 2 comprised 1776 subjects. The mean eGFR was 29.4 ± 14.4 mL/min. In Cohort 1, LDL-CF was highly correlated with LDL-Cmeas (R2 = 0.92) but significantly underestimated LDLmeas by 11 mg/dL. LDL-C = cholesterol - HDL - triglycerides/7.98 was derived as the optimal equation for the calculation of LDL-C in Cohort 1 and was successfully validated in Cohort 2 (bias of 1.6 mg/dL). The novel formula had a higher accuracy than both the Friedewald (bias -12.2 mg/dL) and the Martin's formula (bias -4.8 mg/dL).

CONCLUSION 

The Friedewald formula yields lower LDL-C concentrations in CKD than direct enzymatic measurements, which may lead to undersupply of this cardiovascular high-risk population in a treat-to-target approach.

Lipid Disorders in NAFLD and Chronic Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver dysfunction and is characterized by exaggerated lipid accumulation, inflammation and even fibrosis. It has been shown that NAFLD increases the risk of other chronic diseases, particularly chronic kidney disease (CKD). Lipid in excess could lead to liver and kidney lesions and even end-stage disease through diverse pathways. Dysregulation of lipid uptake, oxidation or de novo lipogenesis contributes to the toxic effects of ectopic lipids which promotes the development and progression of NAFLD and CKD via triggering oxidative stress, apoptosis, pro-inflammatory and profibrotic responses. Importantly, dyslipidemia and release of pro-inflammatory cytokines caused by NAFLD (specifically, nonalcoholic steatohepatitis) are considered to play important roles in the pathological progression of CKD. Growing evidence of similarities between the pathogenic mechanisms of NAFLD and those of CKD has attracted attention and urged researchers to discover their common therapeutic targets. Here, we summarize the current understanding of molecular aberrations underlying the lipid metabolism of NAFLD and CKD and clinical evidence that suggests the relevance of these pathways in humans. This review also highlights the orchestrated inter-organ cross-talk in lipid disorders, as well as therapeutic options and opportunities to counteract NAFLD and CKD.

Association of Kidney Function With NMR-Quantified Lipids, Lipoproteins, and Metabolic Measures in Mexican Adults

CONTEXT

Chronic kidney disease (CKD) and diabetes are associated with dyslipidemia, metabolic abnormalities, and atherosclerotic risk. Nuclear magnetic resonance (NMR) spectroscopy provides much more detail on lipoproteins than traditional assays.

METHODS

In about 38 000 participants from the Mexico City Prospective Study, aged 35 to 84 years and not using lipid-lowering medication, NMR spectroscopy quantified plasma concentrations of lipoprotein particles, their lipidic compositions, and other metabolic measures. Linear regression related low estimated glomerular filtration rate (eGFR; <60 mL/min/1.73 m2) to each NMR measure after adjustment for confounders and for multiplicity. Analyses were done separately for those with and without diabetes.

RESULTS

Among the 38 081 participants (mean age 52 years, 64% women), low eGFR was present for 4.8% (306/6403) of those with diabetes and 1.2% (365/31 678) of those without diabetes. Among both those with and without diabetes, low eGFR was significantly associated with higher levels of 58 NMR measures, including apolipoprotein B (Apo-B), the particle numbers of most Apo-B containing lipoproteins, the cholesterol and triglycerides carried in these lipoproteins, several fatty acids, total cholines and phosphatidylcholine, citrate, glutamine, phenylalanine, β-OH-butyrate, and the inflammatory measure glycoprotein-A, and significantly lower levels of 13 NMR measures, including medium and small high-density lipoprotein particle measures, very low-density lipoprotein particle size, the ratio of saturated:total fatty acids, valine, tyrosine, and aceto-acetate.

CONCLUSIONS

In this Mexican population with high levels of adiposity and diabetes, low kidney function was associated with widespread alterations in lipidic and metabolic profiles, both in those with and without diabetes. These alterations may help explain the higher atherosclerotic risk experienced by people with CKD.

7-Ketocholesterol: Effects on viral infections and hypothetical contribution in COVID-19

7-Ketocholesterol, which is one of the earliest cholesterol oxidization products identified, is essentially formed by the auto-oxidation of cholesterol. In the body, 7-ketocholesterol is both provided by food and produced endogenously. This pro-oxidant and pro-inflammatory molecule, which can activate apoptosis and autophagy at high concentrations, is an abundant component of oxidized Low Density Lipoproteins. 7-Ketocholesterol appears to significantly contribute to the development of age-related diseases (cardiovascular diseases, age-related macular degeneration, and Alzheimer's disease), chronic inflammatory bowel diseases and to certain cancers. Recent studies have also shown that 7-ketocholesterol has anti-viral activities, including on SARS-CoV-2, which are, however, lower than those of oxysterols resulting from the oxidation of cholesterol on the side chain. Furthermore, 7-ketocholesterol is increased in the serum of moderately and severely affected COVID-19 patients. In the case of COVID-19, it can be assumed that the antiviral activity of 7-ketocholesterol could be counterbalanced by its toxic effects, including pro-oxidant, pro-inflammatory and pro-coagulant activities that might promote the induction of cell death in alveolar cells. It is therefore suggested that this oxysterol might be involved in the pathophysiology of COVID-19 by contributing to the acute respiratory distress syndrome and promoting a deleterious, even fatal outcome. Thus, 7-ketocholesterol could possibly constitute a lipid biomarker of COVID-19 outcome and counteracting its toxic effects with adjuvant therapies might have beneficial effects in COVID-19 patients.

Narrative Review of Carotid disease and the kidney

Patients with chronic kidney disease (CKD) have an increased cardiovascular (CV) risk that is only in part explained by established risk factors. Carotid arteriosclerosis and atherosclerosis are increased in CKD, play a role in the causation of CV disease in these patients and can affect the progression of renal disease. The arterial stiffening process is evident even in CKD patients with a very mild reduction of glomerular filtration rate (GFR) whereas arterial thickening is evident in more advanced stages. Possible mechanisms include functional and structural alterations of the arterial wall. Arterial stiffness can mediate the effect of CKD on target organs (i.e., brain, kidney and heart). In this review we discuss the arterial phenotype of patients with CKD. This is characterized by increased common carotid artery stiffness and outward remodeling (enlargement and thickening of the arterial wall) and a normal/reduced stiffness paired with an inward remodeling (narrowing of the arterial wall) of muscular arteries. We also discuss the consequences of carotid dysfunction, including the involvement of large elastic arteries stiffness on ventricular-vascular coupling, the mechanisms linking carotid stiffening and increased cardio- and cerebrovascular risk in CKD patients, and the therapeutic options to improve carotid function.

Overview of Lipidomic Analysis of Triglyceride Molecular Species in Biological Lipid Extracts

Triglyceride (TG) is a class of neutral lipids, which functions as an energy storage depot and is important for cellular growth, metabolism, and function. The composition and content of TG molecular species are crucial factors for nutritional aspects in food chemistry and are directly associated with several diseases, including atherosclerosis, diabetes, obesity, stroke, etc. As a result of the complexities of aliphatic moieties and their different connections/locations to the glycerol backbone in TG molecules, accurate identification of individual TG molecular species and quantitative assessment of TG composition and content are particularly challenging, even at the current stage of lipidomics development. Herein, methods developed for analysis of TG species, such as liquid chromatography-mass spectrometry with a variety of columns and different mass spectrometric techniques, shotgun lipidomics approaches, and ion-mobility-based analysis, are reviewed. Moreover, the potential limitations of the methods are discussed. It is our sincere hope that the overviews and discussions can provide some insights for researchers to select an appropriate approach for TG analysis and can serve as the basis for those who would like to establish a methodology for TG analysis or develop a new method when novel tools become available. Biologically accurate analysis of TG species with an enabling method should lead us toward improving the nutritional quality, revealing the effects of TG on diseases, and uncovering the underlying biochemical mechanisms related to these diseases.

Dyslipidemia in Patients with Kidney Disease

Cardiovascular (CV) disease (CVD) is the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD) and with end-stage renal disease. CKD has a strong association with dyslipidemia. Dyslipidemias can affect kidney function and increase the risk for CVD development, so it is an important risk factor. Statin therapy can decrease CV events in patients with pre-end-stage CKD and in renal transplant patients, but not in those already on dialysis. This article focuses on epidemiology of CKD, how dyslipidemias confer a higher risk for CVD, the approach to management and treatment of dyslipidemias, and recent guidelines.

Lipid Profiles in Primary Aldosteronism Compared with Essential Hypertension: Propensity-Score Matching Study

BACKGROUND

There has been controversy regarding the association between primary aldosteronism (PA) and dyslipidemia and few studies considered the effects of diabetes and renal function on lipid metabolism. We analyzed lipid profiles of PA patients and compared them to propensity-score (PS)-matched essential hypertension (EH) patients adjusting for glycemic status and renal function.

METHODS

Patients who were diagnosed with PA using a saline-infusion test at Seoul National University Hospital from 2000 to 2018 were retrospectively analyzed. EH patients who had aldosterone-renin ratio (ARR) results were selected as controls. Covariates, including diabetes, were PS-matched for patients with PA, lateralized PA, non-lateralized PA, and high ARR to EH patients, respectively.

RESULTS

Among a total of 80 PA and 80 EH patients, total cholesterol (TC) and triglyceride (TG) levels were significantly lower in the PA patients than in the EH patients (least-squares mean±standard error: 185.5±4.4 mg/dL vs. 196.2±4.4 mg/dL, P=0.047, for TC; and 132.3±11.5 mg/dL vs. 157.4±11.4 mg/dL, P=0.035, for TG) in fully adjusted model (adjusting for multiple covariates, including diabetes status, glycosylated hemoglobin level, and estimated glomerular filtration rate). There were no significant differences in high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol levels between the two groups. According to increments in aldosterone levels, an increasing tendency of HDL-C and decreasing tendencies of TG and non-HDL-C were observed.

CONCLUSION

PA patients had lower TC and TG levels than EH patients, independent of glycemic status and renal function.

The Association between Decreased Kidney Function and FIB-4 Index Value, as Indirect Liver Fibrosis Indicator, in Middle-Aged and Older Subjects

Liver fibrosis might be linked to the prevalence of chronic kidney disease (CKD). However, there is little information about the association between liver fibrosis and decreased kidney function in middle-aged and older subjects. We aimed to evaluate the influence of liver fibrosis on the incidence or prevalence of CKD stage 3–5 in a retrospective cross-sectional study (Study 1, n = 806) and a 6-year longitudinal study (Study 2, n = 380) of middle-aged and older subjects. We evaluated liver fibrosis using the Fibrosis-4 (FIB-4) index and kidney function using the estimated glomerular filtration rate (eGFR) of all subjects. All subjects were divided into four groups on the basis of their FIB-4 score quartiles (low to high). In the Jonckheere–Terpstra trend test of Study 1, the eGFR decreased significantly from the lowest group to the highest group (p < 0.001). The Kaplan–Meier survival curve in Study 2 showed that the cumulative prevalence of CKD stage 3–5 was higher in the third quartile than the other quartiles. Our results suggest that liver fibrosis could be a useful indicator for the prevalence of CKD, even within a relatively healthy population, although liver fibrosis was not an independent risk factor.

The causal effects of serum lipids and apolipoproteins on kidney function: multivariable and bidirectional Mendelian-randomization analyses

Background

The causal nature of the observed associations between serum lipids and apolipoproteins and kidney function are unclear.

Methods

Using two-sample and multivariable Mendelian randomization (MR), we examined the causal effects of serum lipids and apolipoproteins on kidney function, indicated by the glomerular-filtration rate estimated using creatinine (eGFRcrea) or cystatin C (eGFRcys) and the urinary albumin-to-creatinine ratio (UACR). We obtained lipid- and apolipoprotein-associated genetic variants from the Global Lipids Genetics Consortium (n = 331 368) and UK Biobank (n = 441 016), respectively, and kidney-function markers from the Trøndelag Health Study (HUNT; n = 69 736) and UK Biobank (n = 464 207). The reverse causal direction was examined using variants associated with kidney-function markers selected from recent genome-wide association studies.

Results

There were no strong associations between genetically predicted lipid and apolipoprotein levels with kidney-function markers. Some, but inconsistent, evidence suggested a weak association of higher genetically predicted atherogenic lipid levels [indicated by low-density lipoprotein cholesterol (LDL-C), triglycerides and apolipoprotein B] with increased eGFR and UACR. For high-density lipoprotein cholesterol (HDL-C), results differed between eGFRcrea and eGFRcys, but neither analysis suggested substantial effects. We found no clear evidence of a reverse causal effect of eGFR on lipid or apolipoprotein traits, but higher UACR was associated with higher LDL-C, triglyceride and apolipoprotein B levels.

Conclusion

Our MR estimates suggest that serum lipid and apolipoprotein levels do not cause substantial changes in kidney function. A possible weak effect of higher atherogenic lipids on increased eGFR and UACR warrants further investigation. Processes leading to higher UACR may lead to more atherogenic lipid levels.

Unconjugated p-cresol activates macrophage macropinocytosis leading to increased LDL uptake

Patients with chronic kidney disease (CKD) and end-stage renal disease suffer from increased cardiovascular events and cardiac mortality. Prior studies have demonstrated that a portion of this enhanced risk can be attributed to the accumulation of microbiota-derived toxic metabolites, with most studies focusing on the sulfonated form of p-cresol (PCS). However, unconjugated p-cresol (uPC) itself was never assessed due to rapid and extensive first-pass metabolism that results in negligible serum concentrations of uPC. These reports thus failed to consider the host exposure to uPC prior to hepatic metabolism. In the current study, not only did we measure the effect of altering the intestinal microbiota on lipid accumulation in coronary arteries, but we also examined macrophage lipid uptake and handling pathways in response to uPC. We found that atherosclerosis-prone mice fed a high-fat diet exhibited significantly higher coronary artery lipid deposits upon receiving fecal material from CKD mice. Furthermore, treatment with uPC increased total cholesterol, triglycerides, and hepatic and aortic fatty deposits in non-CKD mice. Studies employing an in vitro macrophage model demonstrated that uPC exposure increased apoptosis whereas PCS did not. Additionally, uPC exhibited higher potency than PCS to stimulate LDL uptake and only uPC induced endocytosis- and pinocytosis-related genes. Pharmacological inhibition of varying cholesterol influx and efflux systems indicated that uPC increased macrophage LDL uptake by activating macropinocytosis. Overall, these findings indicate that uPC itself had a distinct effect on macrophage biology that might have contributed to increased cardiovascular risk in patients with CKD.

Loss of endothelial glucocorticoid receptor accelerates diabetic nephropathy

Endothelial cells play a key role in the regulation of disease. Defective regulation of endothelial cell homeostasis may cause mesenchymal activation of other endothelial cells or neighboring cell types, and in both cases contributes to organ fibrosis. Regulatory control of endothelial cell homeostasis is not well studied. Diabetes accelerates renal fibrosis in mice lacking the endothelial glucocorticoid receptor (GR), compared to control mice. Hypercholesterolemia further enhances severe renal fibrosis. The fibrogenic phenotype in the kidneys of diabetic mice lacking endothelial GR is associated with aberrant cytokine and chemokine reprogramming, augmented Wnt signaling and suppression of fatty acid oxidation. Both neutralization of IL-6 and Wnt inhibition improve kidney fibrosis by mitigating mesenchymal transition. Conditioned media from endothelial cells from diabetic mice lacking endothelial GR stimulate Wnt signaling-dependent epithelial-to-mesenchymal transition in tubular epithelial cells from diabetic controls. These data demonstrate that endothelial GR is an essential antifibrotic molecule in diabetes.

Lipoprotein Abnormalities in Chronic Kidney Disease and Renal Transplantation

Chronic kidney disease (CKD) is one of the most important risk factors for cardiovascular disease (CVD). Despite the kidney having no direct implications for lipoproteins metabolism, advanced CKD dyslipidemia is usually present in patients with CKD, and the frequent lipid and lipoprotein alterations occurring in these patients play a role of primary importance in the development of CVD. Although hypertriglyceridemia is the main disorder, a number of lipoprotein abnormalities occur in these patients. Different enzymes pathways and proteins involved in lipoprotein metabolism are impaired in CKD. In addition, treatment of uremia may modify the expression of lipoprotein pattern as well as determine acute changes. In renal transplantation recipients, the main lipid alteration is hypercholesterolemia, while hypertriglyceridemia is less pronounced. In this review we have analyzed lipid and lipoprotein disturbances in CKD and also their relationship with progression of renal disease. Hypolipidemic treatments may also change the natural history of CVD in CKD patients and may represent important strategies in the management of CKD patients.

Epicardial fat tissue, coronary arterial calcification and mortality in patients with advanced chronic kidney disease and hemodialysis

INTRODUCTION AND OBJECTIVES

Epicardial and mediastinal adipose tissue (EAT, MAT) are linked to metabolic syndrome and coronary artery disease. Patients with chronic kidney disease (CKD) have thicker EAT. We assessed if EAT and MAT could be associated with increased mortality and cardiovascular events in patients with advanced CKD and haemodialysis therapy.

METHODS

A post-hoc study was performed. We analyzed a prospective series of 104 cases. EAT thickness was quantified by a multislice synchronized computed tomography (MSCT).

RESULTS

The follow-up period was 112.68 (109.94-115.42) months. The optimal cut-off point of EAT for prediction of total mortality was 11.45 mm (92.86% and 43.75%). EAT thickness was associated with serum albumin levels, serum triglyceride levels, phosphorus and calcium phosphate product. The EAT was greater in haemodialysis patients compared to those with advanced CKD (P < .001). Patients with diabetes mellitus had greater EAT and MAT thickness (P = .018). At the end of follow up, the survival average time of patients with EAT thickness <11.45 mm was 97.48 months vs. 76.65 months for thickness > 11.45 mm (P = .007).

CONCLUSIONS

A higher EAT and MAT thickness was associated with increased mortality. Furthermore, EAT was associated with lower free survival time to fatal and non-fatal cardiovascular events. The measurement of EAT and MAT by MSCT could be a prognostic tool to predict cardiovascular events and mortality risk in advanced CKD patients.

Secondary Causes of Hypertriglyceridemia are Prevalent Among Patients Presenting With Hypertriglyceridemia Induced Acute Pancreatitis

BACKGROUND

Hypertriglyceridemia induced acute pancreatitis (HIAP) is the third common cause of acute pancreatitis. HIAP can result in recurrent attacks of severe AP with significant morbidity and mortality. Hypertriglyceridemia (HTG) could be primary or secondary. Although genetic causes of HTG are well studied, the prevalence of secondary causes of HTG in patients presenting with HIAP is not well characterized. This study aimed to identify the prevalence of risk factors for secondary hypertriglyceridemia among patients presenting with HIAP in a tertiary referral center in a large metropolitan area.

METHODS

This is a retrospective analysis of all patients admitted with AP from August 2012-2017. A subgroup of patients with triglycerides >880 mg/dl were included for analysis. Secondary causes of HTG were identified. Secondary analysis evaluating the severity of pancreatitis was performed.

RESULTS

There were 3,746 patients admitted for AP of which 57 patients had AP and HTG. Of these 57 patients, 70.2% had history of diabetes mellitus, 26.3% had history of heavy alcohol use, 22.8% had chronic kidney disease, 47.3% with obesity, and 21.1% with metabolic syndrome. Two patients were classified as unexplained HTG. Secondary analysis showed a total of 45.6% of patients requiring ICU admission. 26.3% of patients with severe inflammatory pancreatitis and 17.5% of patients with severe necrotizing pancreatitis.

CONCLUSIONS

In our cohort of HIAP, 55 out of 57 patients had secondary causes for HTG. Identifying secondary causes of HTG during acute hospitalization is important to tailor outpatient treatment in order to prevent future admissions with HIAP.

Proteinuria converts hepatic heparan sulfate to an effective proprotein convertase subtilisin kexin type 9 enzyme binding partner

Hepatic uptake of triglyceride-rich remnant lipoproteins is mediated by the low-density lipoprotein receptor, a low-density lipoprotein receptor related protein and the heparan sulfate proteoglycan, syndecan-1. Heparan sulfate proteoglycan also mediates low-density lipoprotein receptor degradation by a regulator of cholesterol homeostasis, proprotein convertase subtilisin kexin type 9 (PCSK9), thereby hampering triglyceride-rich remnant lipoproteins uptake. In this study, we investigated the effects of proteinuria on PCSK9, hepatic heparan sulfate proteoglycan and plasma triglyceride-rich remnant lipoproteins. Adriamycin-injected rats developed proteinuria, elevated triglycerides and total cholesterol (all significantly increased). Proteinuria associated with triglycerides and total cholesterol and serum PCSK9 (all significant associations) without loss of the low-density lipoprotein receptor as evidenced by immunofluorescence staining and western blotting. In proteinuric rats, PCSK9 accumulated in sinusoids, whereas in control rats PCSK9 was localized in the cytoplasm of hepatocytes. Molecular profiling revealed that the heparan sulfate side chains of heparan sulfate proteoglycan to be hypersulfated in proteinuric rats. Competition assays revealed sulfation to be a major determinant for PCSK9 binding. PCSK9 partly colocalized with hypersulfated heparan sulfate in proteinuric rats, but not in control rats. Hence, proteinuria induces hypersulfated hepatic heparan sulfate proteoglycans, increasing their affinity to PCSK9. This might impair hepatic triglyceride-rich remnant lipoproteins uptake, causing proteinuria-associated dyslipidemia. Thus, our study reveals PCSK9/heparan sulfate may be a novel target to control dyslipidemia.

Habitual coffee intake and plasma lipid profile: Evidence from UK Biobank

BACKGROUND & AIMS

There is evidence that long-term heavy coffee consumption may adversely affect individuals' cardiovascular disease (CVD) risk. As hyperlipidemia is a well-established contributor to CVD risk, we investigated the association between habitual coffee intake and plasma lipid profile.

METHODS

We used data from up to 362,571 UK Biobank participants to examine phenotypic associations between self-reported coffee intake and plasma lipid profiles, including low-density-lipoproteins cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (total-C), triglycerides, and apolipoproteins A1 and B (ApoA1 and ApoB). Mendelian randomization (MR) analysis using genetically instrumented coffee intake was used to interrogate the causal nature of coffee-lipid associations.

RESULTS

We observed a positive dose-dependent association between self-reported coffee intake and plasma concentration of LDL-C, ApoB and total-C, with the highest lipid levels seen among participants reported drinking >6 cups/day (P_{linear trend}≤ 3.24E-55 for all). Consistently, in MR analyses using genetically instrumented coffee intake one cup higher coffee intake was associated with a 0.07 mmol/L (95% CI 0.03 to 0.12), 0.02 g/L (95% CI 0.01 to 0.03), and 0.09 mmol/L (95% CI 0.04 to 0.14) increase in plasma concentration of LDL-C, ApoB, and total-C, respectively.

CONCLUSIONS

Our phenotypic and genetic analyses suggest that long-term heavy coffee consumption may lead to unfavourable lipid profile, which could potentially increase individuals' risk for CVD. These findings may have clinical relevance for people with elevated LDL cholesterol.