Endothelial nitric oxide synthase impairment is restored by clofibrate treatment in an animal model of hypertension

Machine Learning-Based Integrated Analysis of PANoptosis Patterns in Acute Myeloid Leukemia Reveals a Signature Predicting Survival and Immunotherapy

Objective

We conducted a meticulous bioinformatics analysis leveraging expression data of 226 PANRGs obtained from previous studies, as well as clinical data from AML patients derived from the HOVON database.

Methods

Through meticulous data analysis and manipulation, we were able to categorize AML cases into two distinct PANRG clusters and subsequently identify differentially expressed genes (PRDEGs) with prognostic significance. Furthermore, we organized the patient data into two corresponding gene clusters, allowing us to investigate the intricate relationship between the risk score, patient prognosis, and the immune landscape.

Results

Our findings disclosed significant associations between the identified PANRGs, gene clusters, patient survival, immune system, and cancer-related biological processes and pathways. Importantly, we successfully constructed a prognostic signature comprising nineteen genes, enabling the stratification of patients into high-risk and low-risk groups based on individually calculated risk scores. Furthermore, we developed a robust and practical nomogram model, integrating the risk score and other pertinent clinical features, to facilitate accurate patient survival prediction. Our comprehensive analysis demonstrated that the high-risk group exhibited notably worse prognosis, with the risk score proving to be significantly correlated with infiltration of most immune cells. The qRT-PCR results revealed significant differential expression patterns of LGR5 and VSIG4 in normal and human leukemia cell lines (HL-60 and MV-4-11).

Conclusions

Our findings underscore the potential utility of PANoptosis-based molecular clustering and prognostic signatures as predictive tools for assessing patient survival in AML.

The role of peroxisome proliferator-activated receptors in healthy and diseased eyes

Peroxisome Proliferator-Activated Receptors (PPARs) are a family of nuclear receptors that play essential roles in modulating cell differentiation, inflammation, and metabolism. Three subtypes of PPARs are known: PPAR-alpha (PPARα), PPAR-gamma (PPARγ), and PPAR-beta/delta (PPARβ/δ). PPARα activation reduces lipid levels and regulates energy homeostasis, activation of PPARγ results in regulation of adipogenesis, and PPARβ/δ activation increases fatty acid metabolism and lipolysis. PPARs are linked to various diseases, including but not limited to diabetes, non-alcoholic fatty liver disease, glaucoma and atherosclerosis. In the past decade, numerous studies have assessed the functional properties of PPARs in the eye and key PPAR mechanisms have been discovered, particularly regarding the retina and cornea. PPARγ and PPARα are well established in their functions in ocular homeostasis regarding neuroprotection, neovascularization, and inflammation, whereas PPARβ/δ isoform function remains understudied. Naturally, studies on PPAR agonists and antagonists, associated with ocular pathology, have also gained traction with the development of PPAR synthetic ligands. Studies on PPARs has significantly influenced novel therapeutics for diabetic eye disease, ocular neuropathy, dry eye, and age-related macular degeneration (AMD). In this review, therapeutic potentials and implications will be highlighted, as well as reported adverse effects. Further investigations are necessary before any of the PPARs ligands can be utilized, in the clinics, to treat eye diseases. Future research on the prominent role of PPARs will help unravel the complex mechanisms involved in order to prevent and treat ocular diseases.

Clofibrate improves myocardial ischemia-induced damage through regulation of renin-angiotensin system and favours a pro-vasodilator profile in left ventricle

Myocardial ischemia initiates a chain of pathological conditions leading to cardiomyocyte death. Therefore, pharmacological treatment to stop ischemia-induced damage is necessary. Fibrates, have been reported to decrease inflammatory markers and to modulate the renin-angiotensin system (RAS). Our aim was to explore if clofibrate treatment, administered one week after myocardial event, decreases MI-induced cardiac damage. Wistar rats were assigned to: 1. Sham or 2. Coronary artery ligation (MI). Seven days after, rats were subdivided to receive vehicle (V) or clofibrate [100 mg/kg (C)] daily for 7 days. Blood samples and left ventricle were analyzed. RAS components [angiotensin II, angiotensin converting enzyme (ACE), and AT₁-receptor] decreased in MI-C compared to MI-V, while [Ang-(1-7), bradykinin, ACE-2, and AT₂-receptor] raised in response to clofibrate treatment. Oxidative stress markers increased in MI-V rats, a profile reverted in MI-C rats. Nitric oxide (NO) pathway (Akt, eNOS, and NO) exhibits a lower participation in MI-V, but clofibrate raised NO-pathway components and its production. MI-induced fibrosis and structural damage was also improved by clofibrate-treatment. In conclusion, clofibrate administration to 7 days MI-rats exerts an antioxidant, pro-vasodilator expression profile, and anti-fibrotic effect suggesting that PPARα activation can be considered a therapeutic target to improve cardiac condition posterior to ischemia.

Vasoregression: A Shared Vascular Pathology Underlying Macrovascular And Microvascular Pathologies?

Vasoregression is a common phenomenon underlying physiological vessel development as well as pathological microvascular diseases leading to peripheral neuropathy, nephropathy, and vascular oculopathies. In this review, we describe the hallmarks and pathways of vasoregression. We argue here that there is a parallel between characteristic features of vasoregression in the ocular microvessels and atherosclerosis in the larger vessels. Shared molecular pathways and molecular effectors in the two conditions are outlined, thus highlighting the possible systemic causes of local vascular diseases. Our review gives us a system-wide insight into factors leading to multiple synchronous vascular diseases. Because shared molecular pathways might usefully address the diagnostic and therapeutic needs of multiple common complex diseases, the literature analysis presented here is of broad interest to readership in integrative biology, rational drug development and systems medicine.

Fenofibrate plus Metformin Produces Cardioprotection in a Type 2 Diabetes and Acute Myocardial Infarction Model

We investigated whether fenofibrate, metformin, and their combination generate cardioprotection in a rat model of type 2 diabetes (T2D) and acute myocardial infarction (AMI). Streptozotocin-induced diabetic- (DB-) rats received 14 days of either vehicle, fenofibrate, metformin, or their combination and immediately after underwent myocardial ischemia/reperfusion (I/R). Fenofibrate plus metformin generated cardioprotection in a DBI/R model, reported as decreased coronary vascular resistance, compared to DBI/R-Vehicle, smaller infarct size, and increased cardiac work. The subchronic treatment with fenofibrate plus metformin increased, compared with DBI/R-Vehicle, total antioxidant capacity, manganese-dependent superoxide dismutase activity (MnSOD), guanosine triphosphate cyclohydrolase I (GTPCH-I) expression, tetrahydrobiopterin : dihydrobiopterin (BH₄ : BH₂) ratio, endothelial nitric oxide synthase (eNOS) activity, nitric oxide (NO) bioavailability, and decreased inducible NOS (iNOS) activity. These findings suggest that PPARα activation by fenofibrate + metformin, at low doses, generates cardioprotection in a rat model of T2D and AMI and may represent a novel treatment strategy to limit I/R injury in patients with T2D.

Restoration of Endothelial Function in Pparα (-/-) Mice by Tempol

Peroxisome proliferator activated receptor alpha (PPARα) is one of the PPAR isoforms belonging to the nuclear hormone receptor superfamily that regulates genes involved in lipid and lipoprotein metabolism. PPARα is present in the vascular wall and is thought to be involved in protection against vascular disease. To determine if PPARα contributes to endothelial function, conduit and cerebral resistance arteries were studied in Pparα^−/− mice using isometric and isobaric tension myography, respectively. Aortic contractions to PGF_2α and constriction of middle cerebral arteries to phenylephrine were not different between wild type (WT) and Pparα^−/−; however, relaxation/dilation to acetylcholine (ACh) was impaired. There was no difference in relaxation between WT and Pparα^−/− aorta to treatment with a nitric oxide (NO) surrogate indicating impairment in endothelial function. Endothelial NO levels as well as NO synthase expression were reduced in Pparα^−/− aortas, while superoxide levels were elevated. Two-week feeding with the reactive oxygen species (ROS) scavenger, tempol, normalized ROS levels and rescued the impaired endothelium-mediated relaxation in Pparα^−/− mice. These results suggest that Pparα^−/− mice have impaired endothelial function caused by decreased NO bioavailability. Therefore, activation of PPARα receptors may be a therapeutic target for maintaining endothelial function and protection against cardiovascular disease.

Therapeutic Effects of PPAR α on Neuronal Death and Microvascular Impairment

Peroxisome-proliferator activated receptor-alpha (PPARα) is a broadly expressed nuclear hormone receptor and is a transcription factor for diverse target genes possessing a PPAR response element (PPRE) in the promoter region. The PPRE is highly conserved, and PPARs thus regulate transcription of an extensive array of target genes involved in energy metabolism, vascular function, oxidative stress, inflammation, and many other biological processes. PPARα has potent protective effects against neuronal cell death and microvascular impairment, which have been attributed in part to its antioxidant and anti-inflammatory properties. Here we discuss PPARα's effects in neurodegenerative and microvascular diseases and also recent clinical findings that identified therapeutic effects of a PPARα agonist in diabetic microvascular complications.

PPARα ligand clofibrate ameliorates blood pressure and vascular reactivity in spontaneously hypertensive rats

AIM

Peroxisome proliferator activated receptors (PPARs) are nuclear transcription factors that regulate numerous genes influencing blood pressure. The aim of this study was to examine the effects of clofibrate, a PPARα ligand, on blood pressure in spontaneously hypertensive rats (SHR).

METHODS

Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), 8-9 weeks old, were randomly allocated into groups treated with vehicle or clofibrate (250 mg·kg(-1)·d(-1), ip for 21 d). Systolic blood pressure (SBP) was measured before and after the study period using tail-cuff plethysmography. Rats were sacrificed under anesthesia and blood, urine and tissue samples were processed for subsequent analysis.

RESULTS

SHR rats showed significantly higher SBP compared with WKY rats (198±6 mmHg vs 93±7 mmHg), and a 3-fold increase in urinary protein excretion. Clofibrate treatment reduced SBP by 26%±2% and proteinuria by 43%±9% in SHR but not in WKY rats. The urinary nitrite/nitrate excretion in SHR rats was nearly 2-fold greater than that in WKY, and was further increased by 30%±4% and 48%±3%, respectively, following clofibrate treatment. In addition, PPARα protein expression and PPARα activity were significantly lower in SHR than that in WKY rats. Clofibrate treatment significantly increased PPARα protein expression and PPARα activity in SHR rats, but not in WKY rats. Moreover, the vasoconstrictor response of aortic ring was markedly increased in SHRs, which was blunted after clofibrate treatment.

CONCLUSION

PPARα contributes to regulation of blood pressure and vascular reactivity in SHR, and clofibrate-mediated reduction in blood pressure and proteinuria is probably through increased NO production.