Fenofibrate-induced renal dysfunction, yes or no?

Future Directions in Diabetic Retinopathy Treatment: Stem Cell Therapy, Nanotechnology, and PPARα Modulation

This narrative review focuses on innovative treatment approaches to diabetic retinopathy to meet the urgent demand for advancements in managing both the early and late stages of the disease. Recent studies highlight the potential of adipose stem cells and their secreted factors in mitigating the retinal complications of diabetes, with promising results in improving visual acuity and reducing inflammation and angiogenesis in diabetic retinopathy. However, caution is warranted regarding the safety and long-term therapeutic effects of adipose stem cells transplantation. Bone marrow mesenchymal stem cells can also mitigate retinal damage in diabetic retinopathy. Studies demonstrate that bone marrow mesenchymal stem cells-derived exosomes can suppress the Wnt/β-catenin pathway, reducing oxidative stress, inflammation, and angiogenesis in the diabetic retina, offering promise for future diabetic retinopathy treatments. Nanotechnology has the ability to precisely target the retina and minimize systemic side effects. Nanoparticles and nanocarriers offer improved bioavailability, sustained release of therapeutics, and potential for synergistic effects. They can be a new way of effective treatment and prevention of diabetic retinopathy. Activation and modulation of PPARα as a means for diabetic retinopathy treatment has been widely investigated in recent years and demonstrated promising effects in clinical trials. PPARα activation turned out to be a promising therapeutic method for treating dyslipidemia, inflammation, and insulin sensitivity. The combination of PPARα modulators with small molecules offers an interesting perspective for retinal diseases' therapy.

Fenofibrate and risk of end-stage renal disease: A nationwide cohort study

AIM

Previous studies have shown that fenofibrate improves outcomes such as albuminuria and estimated glomerular filtration rate decline. We hypothesize that fenofibrate has renoprotective effects and prevents or delays the development of end-stage renal disease. The objective of this study is to investigate the risk of incident end-stage renal disease in relation to fenofibrate treatment in patients who are already taking statins.

MATERIALS AND METHODS

We performed a nationwide population-based cohort study using data from the Korea National Health Information Database from 2010 to 2017. Among adults using statins, 413 715 fenofibrate users were compared with 413 715 fenofibrate non-users after 1:1 age, sex and triglyceride matching. The endpoint of this study was incident end-stage renal disease.

RESULTS

During a median 3.96-year follow-up, the incidence per 1000 person years of end-stage renal disease was lower in fenofibrate users than in fenofibrate non-users (0.885 vs. 0.960, p < 0.0001). The hazard ratio for end-stage renal disease was lower (0.763, 95% confidence interval 0.710-0.821) in fenofibrate users. This association was significant in patients with hypertension, proteinuria and an estimated glomerular filtration rate <60 mL/min/1.732.

CONCLUSIONS

Fenofibrate use in patients taking statins with either hypertension, proteinuria, or decreased estimated glomerular filtration rate is associated with a low risk of incident end-stage renal disease. To confirm the renoprotective effect of fenofibrate in chronic kidney disease, a randomized controlled trial is warranted.

Protective Effect of Pemafibrate Treatment against Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats

Diabetic retinopathy (DR) can cause visual impairment and blindness, and the increasing global prevalence of diabetes underscores the need for effective therapies to prevent and treat DR. Therefore, this study aimed to evaluate the protective effect of pemafibrate treatment against DR, using a Spontaneously Diabetic Torii (SDT) fatty rat model of obese type 2 diabetes. SDT fatty rats were fed either a diet supplemented with pemafibrate (0.3 mg/kg/day) for 16 weeks, starting at 8 weeks of age (Pf SDT fatty: study group), or normal chow (SDT fatty: controls). Normal chow was provided to Sprague-Dawley (SD) rats (SD: normal controls). Electroretinography (ERG) was performed at 8 and 24 weeks of age to evaluate the retinal neural function. After sacrifice, retinal thickness, number of retinal folds, and choroidal thickness were evaluated, and immunostaining was performed for aquaporin-4 (AQP4). No significant differences were noted in food consumption, body weight, or blood glucose level after pemafibrate administration. Triglyceride levels were reduced, and high-density lipoprotein cholesterol levels were increased. Extension of oscillatory potential (OP)1 and OP3 waves on ERG was suppressed in the Pf SDT fatty group. Retinal thickness at 1,500 microns from the optic disc improved in the Pf SDT fatty group. No significant improvements were noted in choroidal thickness or number of retinal folds. Quantitative analyses showed that AQP4-positive regions in the retinas were significantly larger in the Pf SDT fatty group than in the SDT fatty group. The findings suggest that pemafibrate treatment can exert protective effects against DR.

Executive summary of the Hellenic Atherosclerosis Society guidelines for the diagnosis and treatment of dyslipidemias - 2023

Atherosclerotic cardiovascular disease (ASCVD) remains the main cause of death worldwide, and thus its prevention, early diagnosis and treatment is of paramount importance. Dyslipidemia represents a major ASCVD risk factor that should be adequately managed at different clinical settings. 2023 guidelines of the Hellenic Atherosclerosis Society focus on the assessment of ASCVD risk, laboratory evaluation of dyslipidemias, new and emerging lipid-lowering drugs, as well as diagnosis and treatment of lipid disorders in women, the elderly and in patients with familial hypercholesterolemia, acute coronary syndromes, heart failure, stroke, chronic kidney disease, diabetes, autoimmune diseases, and non-alcoholic fatty liver disease. Statin intolerance is also discussed.

Fenofibrate reduces glucose-induced barrier dysfunction in feline enteroids

Diabetes mellitus (DM) is a common chronic metabolic disease in humans and household cats that is characterized by persistent hyperglycemia. DM is associated with dysfunction of the intestinal barrier. This barrier is comprised of an epithelial monolayer that contains a network of tight junctions that adjoin cells and regulate paracellular movement of water and solutes. The mechanisms driving DM-associated barrier dysfunction are multifaceted, and the direct effects of hyperglycemia on the epithelium are poorly understood. Preliminary data suggest that fenofibrate, An FDA-approved peroxisome proliferator-activated receptor-alpha (PPARα) agonist drug attenuates intestinal barrier dysfunction in dogs with experimentally-induced DM. We investigated the effects of hyperglycemia-like conditions and fenofibrate treatment on epithelial barrier function using feline intestinal organoids. We hypothesized that glucose treatment directly increases barrier permeability and alters tight junction morphology, and that fenofibrate administration can ameliorate these deleterious effects. We show that hyperglycemia-like conditions directly increase intestinal epithelial permeability, which is mitigated by fenofibrate. Moreover, increased permeability is caused by disruption of tight junctions, as evident by increased junctional tortuosity. Finally, we found that increased junctional tortuosity and barrier permeability in hyperglycemic conditions were associated with increased protein kinase C-α (PKCα) activity, and that fenofibrate treatment restored PKCα activity to baseline levels. We conclude that hyperglycemia directly induces barrier dysfunction by disrupting tight junction structure, a process that is mitigated by fenofibrate. We further propose that counteracting modulation of PKCα activation by increased intracellular glucose levels and fenofibrate is a key candidate regulatory pathway of tight junction structure and epithelial permeability.

Effects of Fenofibrate and Gemfibrozil on Kynurenic Acid Production in Rat Kidneys In Vitro: Old Drugs, New Properties

Kidney dysfunction significantly increases the cardiovascular risk, even in cases of minor functional declines. Hypertriglyceridemia is the most common lipid abnormality reported in patients with kidney disorders. PPAR-α (peroxisome proliferator-activated receptor-α) agonists called fibrates are the main agents used to lower triglyceride levels. Kynurenic acid (KYNA) is a tryptophan (Trp) derivative directly formed from L-kynurenine (L-KYN) by kynurenine aminotransferases (KATs). KYNA is classified as a uremic toxin, the level of which is correlated with kidney function impairments and lipid abnormalities. The aim of this study was to analyze the effect of the most commonly used triglyceride-lowering drugs, fenofibrate and gemfibrozil, on KYNA production and KAT activity in rat kidneys in vitro. The influence of fenofibrate and gemfibrozil on KYNA formation and KAT activity was tested in rat kidney homogenates in vitro. Fenofibrate and gemfibrozil at 100 µM-1 mM significantly inhibited KYNA synthesis in rat kidney homogenates. Both fibrates directly affected the KAT I and KAT II isoenzyme activities in a dose-dependent manner at similar concentrations. The presented results reveal the novel mechanism of action of fibrates in the kidneys and suggest their potential role in kidney function protection beyond the well-known anti-hyperlipidemic effect.

Can coenzyme Q10 alleviate the toxic effect of fenofibrate on skeletal muscle?

Fenofibrate (FEN) is an antilipidemic drug that increases the activity of the lipoprotein lipase enzyme, thus enhancing lipolysis; however, it may cause myopathy and rhabdomyolysis in humans. Coenzyme Q10 (CoQ10) is an endogenously synthesized compound that is found in most living cells and plays an important role in cellular metabolism. It acts as the electron carrier in the mitochondrial respiratory chain. This study aimed to elucidate FEN-induced skeletal muscle changes in rats and to evaluate CoQ10 efficacy in preventing or alleviating these changes. Forty adult male rats were divided equally into four groups: the negative control group that received saline, the positive control group that received CoQ10, the FEN-treated group that received FEN, and the FEN + CoQ10 group that received both FEN followed by CoQ10 daily for 4 weeks. Animals were sacrificed and blood samples were collected to assess creatine kinase (CK). Soleus muscle samples were taken and processed for light and electron microscopic studies. This study showed that FEN increased CK levels and induced inflammatory cellular infiltration and disorganization of muscular architecture with lost striations. FEN increased the percentage of degenerated collagen fibers and immune expression of caspase-3. Ultrastructurally, FEN caused degeneration of myofibrils with distorted cell organelles. Treatment with CoQ10 could markedly ameliorate these FEN-induced structural changes and mostly regain the normal architecture of muscle fibers due to its antifibrotic and antiapoptotic effects. In conclusion, treatment with CoQ10 improved muscular structure by suppressing oxidative stress, attenuating inflammation, and inhibiting apoptosis.

Factors associated with incidence of acute kidney injury: a Japanese regional population-based cohort study, the Shizuoka study

BACKGROUND

Acute kidney injury (AKI) is a globally critical issue. Most studies about AKI have been conducted in limited settings on perioperative or critically ill patients. As a result, there is little information about the epidemiology and risk factors of AKI in the general population.

METHODS

We conducted a population-based cohort study using the Shizuoka Kokuho Database. We included subjects with records of health checkup results. The observation period for each participant was defined as from the date of insurance enrollment or April 2012, whichever occurred later, until the date of insurance withdrawal or September 2020, whichever was later. Primary outcome was AKI associated with admission based on the ICD-10 code. We described the incidence of AKI and performed a multivariate analysis using potential risk factors selected from comorbidities, medications, and health checkup results.

RESULTS

Of 627,814 subjects, 8044 were diagnosed with AKI (incidence 251 per 100,000 person-years). The AKI group was older, with more males. Most comorbidities and prescribed medications were more common in the AKI group. As novel factors, statins (hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.80-0.89) and physical activity habits (HR 0.79, 95% CI 0.75-0.83) were associated with reduced incidence of AKI. Other variables associated with AKI were approximately consistent with those from previous studies.

CONCLUSIONS

The factors associated with AKI and the incidence of AKI in the general Japanese population are indicated. This study generates the hypothesis that statins and physical activity habits are novel protective factors for AKI.

Investigation of the separate and simultaneous bindings of warfarin and fenofibrate to bovine serum albumin

Lipid-lowering drugs are often taken with anticoagulant drugs in hyperlipidemia patients. Fenofibrate (FNBT) and warfarin (WAR) are common clinical lipid-lowering drugs and anticoagulant drugs, respectively. A study of binding affinity, binding force, binding distance, and binding sites was performed to determine the interaction mechanism between drugs and carrier proteins (bovine serum albumin, BSA), as well as their effects on BSA conformation. Both FNBT and WAR can form complexes with BSA by van der Waals force and hydrogen bonds. WAR had a stronger fluorescence quenching effect on BSA, a stronger binding affinity, and greater effects on BSA conformation than FNBT. According to fluorescence spectroscopy and cyclic voltammetry, co-administration of drugs decreased one drug's binding constant to BSA and increased its binding distance. This suggested that each drug's binding to BSA was disturbed by each other, as well as each drug's binding ability to BSA was altered by the other. It was demonstrated that co-administration of drugs had greater effects on the secondary structure of BSA and microenvironment polarity surrounding amino acid residues, using multiple spectroscopy techniques, such as ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and synchronous fluorescence spectroscopy.

Effects of fenofibrate therapy on renal function in primary gout patients

Objective

To investigate the incidence and potential risk factors for development of fenofibrate-associated nephrotoxicity in gout patients.

Methods

A total of 983 gout patients on fenofibrate treatment who visited the dedicated Gout Clinic at the Affiliated Hospital of Qingdao University between September 2016 and June 2020 were retrospectively enrolled from the electronic records system. Fenofibrate-associated nephrotoxicity was defined as an increase in serum creatinine (SCr) ≥0.3 mg/dl within 6 months of fenofibrate initiation. The change trend of SCr and uric acid levels during the treatment period were assessed by a generalised additive mixed model (GAMM). Multivariate analysis was performed for risk factors affecting elevated SCr.

Results

A total of 100 (10.2%) patients experienced an increase in SCr ≥0.3 mg/dl within 6 months after fenofibrate initiation. The median change of SCr in the whole cohort was 0.11 mg/dl [interquartile range (IQR) 0.03–0.20], whereas it was 0.36 (0.33–0.45) in the fenofibrate-associated nephrotoxicity group. In a multivariable regression model, chronic kidney disease (CKD) [odds ratio (OR) 2.39 (95% CI 1.48, 3.86)] and tophus [OR 2.29 (95% CI 1.39, 3.78)] were identified to be risk predictors, independent of measured covariates, of fenofibrate-associated nephrotoxicity. During the treatment period, although SCr temporarily increased, serum urate and triglyceride concentrations decreased using the interaction analysis of GAMM. Of those with fenofibrate withdrawal records, the SCr increase in 65% of patients was reversed after an average of 49 days off the drug.

Conclusions

This observational study implied that fenofibrate-associated nephrotoxicity occurs frequently in gout patients, especially in patients with tophi or CKD. The potential renal risks of fenofibrate usage in gout needs additional research.

The role of metabolic reprogramming in tubular epithelial cells during the progression of acute kidney injury

Acute kidney injury (AKI) is one of the most common clinical syndromes. AKI is associated with significant morbidity and subsequent chronic kidney disease (CKD) development. Thus, it is urgent to develop a strategy to hinder AKI progression. Renal tubules are responsible for the reabsorption and secretion of various solutes and the damage to this part of the nephron is a key mediator of AKI. As we know, many common renal insults primarily target the highly metabolically active proximal tubular cells (PTCs). PTCs are the most energy-demanding cells in the kidney. The ATP that they use is mostly produced in their mitochondria by fatty acid β-oxidation (FAO). But, when PTCs face various biological stresses, FAO will shut down for a time that outlives injury. Recent studies have suggested that surviving PTCs can adapt to FAO disruption by increasing glycolysis when facing metabolic constraints, although PTCs do not perform glycolysis in a normal physiological state. Enhanced glycolysis in a short period compensates for impaired energy production and exerts partial renal-protective effects, but its long-term effect on renal function and AKI progression is not promising. Deranged FAO and enhanced glycolysis may contribute to the AKI to CKD transition through different molecular biological mechanisms. In this review, we concentrate on the recent pathological findings of AKI with regards to the metabolic reprogramming in PTCs, confirming that targeting metabolic reprogramming represents a potentially effective therapeutic strategy for the progression of AKI.

Efficacy of a micronized, nanocrystal fenofibrate formulation in treatment of hyperlipidemia in dogs

Background

Safe, effective, and readily available drug therapies are required for the management of hyperlipidemia and its associated complications in dogs.

Objectives

To investigate the efficacy of a micronized, nanocrystal formulation of fenofibrate (Tricor) in the treatment of hyperlipidemia in dogs.

Animals

Ten client‐owned dogs with primary (n = 7) and secondary (n = 3) hyperlipidemia. All dogs had hypertriglyceridemia at baseline; 3 dogs also had hypercholesterolemia.

Methods

Prospective dose‐escalation study. Dogs were treated with fenofibrate orally once daily in up to 3 cycles of 21 days each. Fenofibrate dose was increased at the end of each cycle if hypertriglyceridemia persisted and adverse effects were not documented. Complete blood count, biochemistry, and urine protein:creatinine ratio were collected serially. Baseline (T0) parameters were compared to time of maximal reduction in serum triglyceride concentrations (T1) and reported as median (range).

Results

Triglycerides normalized in all dogs (T0 = 662 mg/dL [189‐2391]; T1 = 113 mg/dL [81‐132]; P = .002). Fenofibrate dose at T1 = 6.4 mg/kg PO q24h (range, 2.2‐13.5). T1 was achieved at 3 (n = 4), 6 (n = 4), and 9 (n = 2) weeks. Serum cholesterol concentrations decreased in 9 of 10 dogs. Quiet demeanor and firm stools in 1 dog were the only reported adverse reactions. Fenofibrate administration resulted in a significant reduction in median alkaline phosphatase activity (P = .049).

Conclusions and Clinical Importance

Over 21 to 63 days, TriCor was effective in the management of primary and secondary hyperlipidemia in dogs.

Design, synthesis, and biological evaluation of a novel dual peroxisome proliferator-activated receptor alpha/delta agonist for the treatment of diabetic kidney disease through anti-inflammatory mechanisms

Diabetic kidney disease (DKD) is a major feature of the final stage of nearly all cause types of diabetes mellitus (DM). To date, few safe and effective drugs are available to treat. Peroxisome proliferator-activated receptors (PPARs), comprised of three members: PPAR-α, PPAR-δ and PPAR-γ, play a protective role in the DKD through glycemic control and lipid metabolism, whereas systemic activation of PPAR-γ causes serious side-effects in clinical trials. GFT505 is a dual PPAR-α/δ agonist, and the selectivity against PPAR-γ is still to be improved. Sulfuretin has been shown to suppress the expression of PPAR-γ and improve the pathogenesis of diabetic complications. In this study, by hybridizing the carboxylic acid of GFT505 and the parent nucleus of sulfuretin, we pioneeringly designed and synthetized a series of novel dual PPAR-α/δ agonists, expecting to provide a better benefit/risk ratio for PPARs. Of all the synthesized compounds, compound 12 was identified with highly activity on PPAR-α/δ and higher selectivity against PPAR-γ than that of GFT505 (EC₅₀: hPPAR-α: 0.26 μM vs.0.76 μM; hPPAR-δ: 0.50 μM vs.0.73 μM; hPPAR-γ: 4.22 μM vs.2.79 μM). The molecular docking studies also depicted good binding affinity of compound 12 for PPAR-α and PPAR-δ compared to GFT505. Furthermore, compound 12 exhibited an evidently renoprotective effect on the DKD through inhibiting inflammatory process, which might at least partly via JNK/NF-κB pathways in vivo and in vitro. Overall, compound 12 hold therapeutic promise for DKD.

PPARα Agonist Oral Therapy in Diabetic Retinopathy

Diabetic retinopathy (DR) is an eye condition that develops after chronically poorly-managed diabetes, and is presently the main cause for blindness on a global scale. Current treatments for DR such as laser photocoagulation, topical injection of corticosteroids, intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents and vitreoretinal surgery are only applicable at the late stages of DR and there are possibilities of significant adverse effects. Moreover, the forms of treatment available for DR are highly invasive to the eyes. Safer and more effective pharmacological treatments are required for DR treatment, in particular at an early stage. In this review, we cover recently investigated promising oral pharmacotherapies, the methods of which are safer, easier to use, patient-friendly and pain-free, in clinical studies. We especially focus on peroxisome proliferator-activator receptor alpha (PPARα) agonists in which experimental evidence suggests PPARα activation may be closely related to the attenuation of vascular damages, including lipid-induced toxicity, inflammation, an excess of free radical generation, endothelial dysfunction and angiogenesis. Furthermore, oral administration of selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) agonists may induce hepatic fibroblast growth factor 21 expression, indirectly resulting in retinal protection in animal studies. Our review will enable more comprehensive approaches for understanding protective roles of PPARα for the prevention of DR development.

Pemafibrate Protects Against Retinal Dysfunction in a Murine Model of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the leading causes of blindness globally. Retinal neuronal abnormalities occur in the early stage in DR. Therefore, maintaining retinal neuronal activity in DR may prevent vision loss. Previously, pemafibrate, a novel selective peroxisome proliferator-activated receptor alpha modulator, was suggested as a promising drug in hypertriglyceridemia. However, the role of pemafibrate remains obscure in DR. Therefore, we aimed to unravel systemic and retinal changes by pemafibrate in diabetes. Adult mice were intraperitoneally injected with streptozotocin (STZ) to induce diabetes. After STZ injection, diet supplemented with pemafibrate was given to STZ-induced diabetic mice for 12 weeks. During the experiment period, body weight and blood glucose levels were examined. Electroretinography was performed to check the retinal neural function. After sacrifice, the retina, liver, and blood samples were subjected to molecular analyses. We found pemafibrate mildly improved blood glucose level as well as lipid metabolism, boosted liver function, increased serum fibroblast growth factor21 level, restored retinal functional deficits, and increased retinal synaptophysin protein expression in STZ-induced diabetic mice. Our present data suggest a promising pemafibrate therapy for the prevention of early DR by improving systemic metabolism and protecting retinal function.