Beyond multiple mechanisms and a unique drug: Defective autophagy as pivotal player in cerebral cavernous malformation pathogenesis and implications for targeted therapies

Cerebral Cavernous Malformation: From Genetics to Pharmacotherapy

INTRODUCTION

Cerebral cavernous malformation (CCM) is a type of cerebrovascular abnormality in the central nervous system linked to both germline and somatic genetic mutations. Recent preclinical and clinical studies have shown that various drugs can effectively reduce the burden of CCM lesions. Despite significant progress, the mechanisms driving CCM remain incompletely understood, and to date, no drugs have been developed that can cure or prevent CCM. This review aims to explore the genetic mutations, molecular mechanisms, and pharmacological interventions related to CCM.

METHODS

Literatures on the genetic mechanisms and pharmacological treatments of CCM can be searched in PubMed and Web of Science.

RESULTS

Germline and somatic mutations mediate the onset and development of CCM through several molecular pathways. Medications such as statins, fasudil, rapamycin, and propranolol can alleviate CCM symptoms or hinder its progression by specifically modulating the corresponding targets.

CONCLUSIONS

Understanding the molecular mechanisms underlying CCM offers potential for targeted therapies. Further research into novel mutations and treatment strategies is essential for improving patient outcomes.

KRIT1: A Traffic Warden at the Busy Crossroads Between Redox Signaling and the Pathogenesis of Cerebral Cavernous Malformation Disease

Significance: KRIT1 (Krev interaction trapped 1) is a scaffolding protein that plays a critical role in vascular morphogenesis and homeostasis. Its loss-of-function has been unequivocally associated with the pathogenesis of Cerebral Cavernous Malformation (CCM), a major cerebrovascular disease of genetic origin characterized by defective endothelial cell-cell adhesion and ensuing structural alterations and hyperpermeability in brain capillaries. KRIT1 contributes to the maintenance of endothelial barrier function by stabilizing the integrity of adherens junctions and inhibiting the formation of actin stress fibers. Recent Advances: Among the multiple regulatory mechanisms proposed so far, significant evidence accumulated over the past decade has clearly shown that the role of KRIT1 in the stability of endothelial barriers, including the blood-brain barrier, is largely based on its involvement in the complex machinery governing cellular redox homeostasis and responses to oxidative stress and inflammation. KRIT1 loss-of-function has, indeed, been demonstrated to cause an impairment of major redox-sensitive mechanisms involved in spatiotemporal regulation of cell adhesion and signaling, which ultimately leads to decreased cell-cell junction stability and enhanced sensitivity to oxidative stress and inflammation. Critical Issues: This review explores the redox mechanisms that influence endothelial cell adhesion and barrier function, focusing on the role of KRIT1 in such mechanisms. We propose that this supports a novel model wherein redox signaling forms the common link between the various pathogenetic mechanisms and therapeutic approaches hitherto associated with CCM disease. Future Directions: A comprehensive characterization of the role of KRIT1 in redox control of endothelial barrier physiology and defense against oxy-inflammatory insults will provide valuable insights into the development of precision medicine strategies. Antioxid. Redox Signal. 38, 496-528.

Heterozygous Loss of KRIT1 in Mice Affects Metabolic Functions of the Liver, Promoting Hepatic Oxidative and Glycative Stress

KRIT1 loss-of-function mutations underlie the pathogenesis of Cerebral Cavernous Malformation (CCM), a major vascular disease affecting the central nervous system (CNS). However, KRIT1 is also expressed outside the CNS and modulates key regulators of metabolic and oxy-inflammatory pathways, including the master transcription factor FoxO1, suggesting a widespread functional significance. Herein, we show that the KRIT1/FoxO1 axis is implicated in liver metabolic functions and antioxidative/antiglycative defenses. Indeed, by performing comparative studies in KRIT1 heterozygous (KRIT1^+/−) and wild-type mice, we found that KRIT1 haploinsufficiency resulted in FoxO1 expression/activity downregulation in the liver, and affected hepatic FoxO1-dependent signaling pathways, which are markers of major metabolic processes, including gluconeogenesis, glycolysis, mitochondrial respiration, and glycogen synthesis. Moreover, it caused sustained activation of the master antioxidant transcription factor Nrf2, hepatic accumulation of advanced glycation end-products (AGEs), and abnormal expression/activity of AGE receptors and detoxifying systems. Furthermore, it was associated with an impairment of food intake, systemic glucose disposal, and plasma levels of insulin. Specific molecular alterations detected in the liver of KRIT1^+/− mice were also confirmed in KRIT1 knockout cells. Overall, our findings demonstrated, for the first time, that KRIT1 haploinsufficiency affects glucose homeostasis and liver metabolic and antioxidative/antiglycative functions, thus inspiring future basic and translational studies.

Next-Generation Sequencing Advances the Genetic Diagnosis of Cerebral Cavernous Malformation (CCM)

Cerebral Cavernous Malformation (CCM) is a cerebrovascular disease of genetic origin that predisposes to seizures, focal neurological deficits and fatal intracerebral hemorrhage. It may occur sporadically or in familial forms, segregating as an autosomal dominant condition with incomplete penetrance and highly variable expressivity. Its pathogenesis has been associated with loss-of-function mutations in three genes, namely KRIT1 (CCM1), CCM2 and PDCD10 (CCM3), which are implicated in defense mechanisms against oxidative stress and inflammation. Herein, we screened 21 Italian CCM cases using clinical exome sequencing and found six cases (~29%) with pathogenic variants in CCM genes, including a large 145−256 kb genomic deletion spanning the KRIT1 gene and flanking regions, and the KRIT1 c.1664C>T variant, which we demonstrated to activate a donor splice site in exon 16. The segregation of this cryptic splicing mutation was studied in a large Italian family (five affected and seven unaffected cases), and showed a largely heterogeneous clinical presentation, suggesting the implication of genetic modifiers. Moreover, by analyzing ad hoc gene panels, including a virtual panel of 23 cerebrovascular disease-related genes (Cerebro panel), we found two variants in NOTCH3 and PTEN genes, which could contribute to the abnormal oxidative stress and inflammatory responses to date implicated in CCM disease pathogenesis.

Vitamin D as therapeutic modulator in cerebrovascular diseases: a mechanistic perspectives

Vitamin D deficiency has been linked to several major chronic diseases, such as cardiovascular and neurodegenerative diseases, diabetes, and cancer, linked to oxidative stress, inflammation, and aging. Vitamin D deficiency appears to be particularly harmful to the cardiovascular system, as it can cause endothelial dysfunctioning and vascular abnormalities through the modulation of various downstream mechanisms. As a result, new research indicates that therapeutic approaches targeting vitamin D inadequacies or its significant downstream effects, such as impaired autophagy, abnormal pro-inflammatory and pro-oxidant reactions, may delay the onset and severity of major cerebrovascular disorders such as stroke and neurologic malformations. Vitamin D modulates the various molecular pathways, i.e., Nitric Oxide, PI3K-Akt Pathway, cAMP pathway, NF-kB Pathway, Sirtuin 1, Nrf2, FOXO, in cerebrovascular disorder. The current review shows evidence for vitamin D's mitigating or slowing the progression of these cerebrovascular disorders, which are significant causes of disability and death worldwide.

A promising field: regulating imbalance of EndMT in cardiovascular diseases

Endothelial-mesenchymal transition (EndMT) is widely involved in the occurrence and development of cardiovascular diseases. Although there is no direct evidence, it is very promising as an effective target for the treatment of these diseases. Endothelial cells need to respond to the complex cardiovascular environment through EndMT, but sustained stimuli will cause the imbalance of EndMT. Blocking the signal transduction promoting EndMT is an effective method to control the imbalance of EndMT. In particular, we also discussed the potential role of endothelial cell apoptosis and autophagy in regulating the imbalance of EndMT. In addition, promoting mesenchymal-endothelial transformation (MEndT) is also a method to control the imbalance of EndMT. However, targeting EndMT to treat cardiovascular disease still faces many challenges. By reviewing the research progress of EndMT, we have put forward some insights and translated them into challenges and opportunities for new treatment strategies for cardiovascular diseases.

Inflammatory injury and mitophagy of the brain in chicken exposed to Cr(VI)

The aim of this study is to determine whether Cr(VI) can induce inflammatory injury in chicken brain and influence mitophagy and related mechanisms. A total of 120 hyline brown chickens (1 day old, 20±3g) were selected and randomly divided into four groups and given different doses of Cr(VI) (0, 10, 30, and 50 mg/kg) every day at 45 days. Results showed that excessive intake of Cr(VI) led to increased tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) levels and decreased interferon-gamma (IF-γ) level. Cr(VI) increased the production of mitochondrial reactive oxygen species (ROS) in chicken brain cells, causing the decline of mitochondrial membrane potential (MMP) and formation of autophagosomes for mitophagy. In addition, Cr(VI) promoted the translocation of Parkin to the mitochondrial outer membrane, increased LC3-II protein level, and inhibited p62 and TOM20 protein expression. In conclusion, excessive Cr(VI) intake can induce inflammatory injury and mitophagy in chicken brain.

Production of KRIT1-knockout and KRIT1-knockin Mouse Embryonic Fibroblasts as Cellular Models of CCM Disease

The development of distinct cellular and animal models has allowed the identification and characterization of molecular mechanisms underlying the pathogenesis of cerebral cavernous malformation (CCM) disease. This is a major cerebrovascular disorder of proven genetic origin, affecting 0.5% of the population. Three disease genes have been identified: CCM1/KRIT1, CCM2, and CCM3. These genes encode for proteins implicated in the regulation of major cellular structures and mechanisms, such as cell-cell and cell-matrix adhesion, actin cytoskeleton dynamics, and endothelial-to-mesenchymal transition, suggesting that they may act as pleiotropic regulators of cellular homeostasis. Indeed, accumulated evidence in cellular and animal models demonstrates that emerged pleiotropic functions of CCM proteins are mainly due to their ability to modulate redox-sensitive pathways and mechanisms involved in adaptive responses to oxidative stress and inflammation, thus contributing to the preservation of cellular homeostasis and stress defenses. In particular, we demonstrated that KRIT1 loss-of-function affects master regulators of cellular redox homeostasis and responses to oxidative stress, including major redox-sensitive transcriptional factors and antioxidant proteins, and autophagy, suggesting that altered redox signaling and oxidative stress contribute to CCM pathogenesis, and opening novel preventive and therapeutic perspectives.In this chapter, we describe materials and methods for isolation of mouse embryonic fibroblast (MEF) cells from homozygous KRIT1-knockout mouse embryos, and their transduction with a lentiviral vector encoding KRIT1 to generate cellular models of CCM disease that contributed significantly to the identification of pathogenetic mechanisms.

Fluorescence Analysis of Reactive Oxygen Species (ROS) in Cellular Models of Cerebral Cavernous Malformation Disease

Cerebral cavernous malformation (CCM) is a vascular disease of proven genetic origin, which may arise sporadically or can be inherited as an autosomal dominant condition with incomplete penetrance and highly variable expressivity. CCM disease exhibits a range of different phenotypes, including wide interindividual differences in lesion number, size, and susceptibility to intracerebral hemorrhage (ICH). Mutations of the KRIT1 gene account for over 50% of familial cases. Previously, we demonstrated that KRIT1 loss-of-function is associated with altered homeostasis of intracellular reactive oxygen species (ROS) and abnormal activation of redox-sensitive transcription factors, which collectively result in pro-oxidative, pro-inflammatory, and pro-angiogenic effects, suggesting a novel pathogenic mechanism for CCM disease. Consistently, these original discoveries have been confirmed and extended by subsequent findings showing mechanistic relationships between pleiotropic redox-dependent effects of KRIT1 loss-of-function and enhanced cell sensitivity to oxidative stress, which may eventually lead to cellular dysfunctions and CCM disease pathogenesis. In this chapter, we describe few basic methods used for qualitative and quantitative analysis of intracellular ROS in cellular models of CCM disease.

From Genes and Mechanisms to Molecular-Targeted Therapies: The Long Climb to the Cure of Cerebral Cavernous Malformation (CCM) Disease

Cerebral cavernous malformation (CCM) is a rare cerebrovascular disorder of genetic origin consisting of closely clustered, abnormally dilated and leaky capillaries (CCM lesions), which occur predominantly in the central nervous system. CCM lesions can be single or multiple and may result in severe clinical symptoms, including focal neurological deficits, seizures, and intracerebral hemorrhage. Early human genetic studies demonstrated that CCM disease is linked to three chromosomal loci and can be inherited as autosomal dominant condition with incomplete penetrance and highly variable expressivity, eventually leading to the identification of three disease genes, CCM1/KRIT1, CCM2, and CCM3/PDCD10, which encode for structurally unrelated intracellular proteins that lack catalytic domains. Biochemical, molecular, and cellular studies then showed that these proteins are involved in endothelial cell-cell junction and blood-brain barrier stability maintenance through the regulation of major cellular structures and mechanisms, including endothelial cell-cell and cell-matrix adhesion, actin cytoskeleton dynamics, autophagy, and endothelial-to-mesenchymal transition, suggesting that they act as pleiotropic regulators of cellular homeostasis, and opening novel therapeutic perspectives. Indeed, accumulated evidence in cellular and animal models has eventually revealed that the emerged pleiotropic functions of CCM proteins are mainly due to their ability to modulate redox-sensitive pathways and mechanisms involved in adaptive responses to oxidative stress and inflammation, thus contributing to the preservation of cellular homeostasis and stress defenses.In this introductory review, we present a general overview of 20 years of amazing progress in the identification of genetic culprits and molecular mechanisms underlying CCM disease pathogenesis, and the development of targeted therapeutic strategies.

Protein kinase Cα regulates the nucleocytoplasmic shuttling of KRIT1

KRIT1 is a scaffolding protein that regulates multiple molecular mechanisms, including cell-cell and cell-matrix adhesion, and redox homeostasis and signaling. However, rather little is known about how KRIT1 is itself regulated. KRIT1 is found in both the cytoplasm and the nucleus, yet the upstream signaling proteins and mechanisms that regulate KRIT1 nucleocytoplasmic shuttling are not well understood. Here, we identify a key role for protein kinase C (PKC) in this process. In particular, we found that PKC activation promotes the redox-dependent cytoplasmic localization of KRIT1, whereas inhibition of PKC or treatment with the antioxidant N-acetylcysteine leads to KRIT1 nuclear accumulation. Moreover, we demonstrated that the N-terminal region of KRIT1 is crucial for the ability of PKC to regulate KRIT1 nucleocytoplasmic shuttling, and may be a target for PKC-dependent regulatory phosphorylation events. Finally, we found that silencing of PKCα, but not PKCδ, inhibits phorbol 12-myristate 13-acetate (PMA)-induced cytoplasmic enrichment of KRIT1, suggesting a major role for PKCα in regulating KRIT1 nucleocytoplasmic shuttling. Overall, our findings identify PKCα as a novel regulator of KRIT1 subcellular compartmentalization, thus shedding new light on the physiopathological functions of this protein.

Towards precision nanomedicine for cerebrovascular diseases with emphasis on Cerebral Cavernous Malformation (CCM)

Introduction: Cerebrovascular diseases encompass various disorders of the brain vasculature, such as ischemic/hemorrhagic strokes, aneurysms, and vascular malformations, also affecting the central nervous system leading to a large variety of transient or permanent neurological disorders. They represent major causes of mortality and long-term disability worldwide, and some of them can be inherited, including Cerebral Cavernous Malformation (CCM), an autosomal dominant cerebrovascular disease linked to mutations in CCM1/KRIT1, CCM2, or CCM3/PDCD10 genes.Areas covered: Besides marked clinical and etiological heterogeneity, some commonalities are emerging among distinct cerebrovascular diseases, including key pathogenetic roles of oxidative stress and inflammation, which are increasingly recognized as major disease hallmarks and therapeutic targets. This review provides a comprehensive overview of the different clinical features and common pathogenetic determinants of cerebrovascular diseases, highlighting major challenges, including the pressing need for new diagnostic and therapeutic strategies, and focusing on emerging innovative features and promising benefits of nanomedicine strategies for early detection and targeted treatment of such diseases.Expert opinion: Specifically, we describe and discuss the multiple physico-chemical features and unique biological advantages of nanosystems, including nanodiagnostics, nanotherapeutics, and nanotheranostics, that may help improving diagnosis and treatment of cerebrovascular diseases and neurological comorbidities, with an emphasis on CCM disease.

Vitamin D Deficiency and the Risk of Cerebrovascular Disease

Vitamin D deficiency has been clearly linked to major chronic diseases associated with oxidative stress, inflammation, and aging, including cardiovascular and neurodegenerative diseases, diabetes, and cancer. In particular, the cardiovascular system appears to be highly sensitive to vitamin D deficiency, as this may result in endothelial dysfunction and vascular defects via multiple mechanisms. Accordingly, recent research developments have led to the proposal that pharmacological interventions targeting either vitamin D deficiency or its key downstream effects, including defective autophagy and abnormal pro-oxidant and pro-inflammatory responses, may be able to limit the onset and severity of major cerebrovascular diseases, such as stroke and cerebrovascular malformations. Here we review the available evidence supporting the role of vitamin D in preventing or limiting the development of these cerebrovascular diseases, which are leading causes of disability and death all over the world.

Dicarbonyl Stress and S-Glutathionylation in Cerebrovascular Diseases: A Focus on Cerebral Cavernous Malformations

Dicarbonyl stress is a dysfunctional state consisting in the abnormal accumulation of reactive α-oxaldehydes leading to increased protein modification. In cells, post-translational changes can also occur through S-glutathionylation, a highly conserved oxidative post-translational modification consisting of the formation of a mixed disulfide between glutathione and a protein cysteine residue. This review recapitulates the main findings supporting a role for dicarbonyl stress and S-glutathionylation in the pathogenesis of cerebrovascular diseases, with specific emphasis on cerebral cavernous malformations (CCM), a vascular disease of proven genetic origin that may give rise to various clinical signs and symptoms at any age, including recurrent headaches, seizures, focal neurological deficits, and intracerebral hemorrhage. A possible interplay between dicarbonyl stress and S-glutathionylation in CCM is also discussed.

Next Generation Sequencing (NGS) Strategies for Genetic Testing of Cerebral Cavernous Malformation (CCM) Disease

The application of next generation sequencing (NGS) technique has a great impact on complex disease studies. Indeed, genetic heterogeneity, phenotypic variability, and disease rarity are all factors that make the traditional diagnostic approach to genetic disorders, whereby a specific gene is selected for sequencing based on the clinical phenotype, very challenging and obsolete.Exome sequencing, which sequences the protein-coding region of the genome, has been rapidly applied to variant discovery in research settings. Recent coverage and accuracy improvements have accelerated the development of clinical exome sequencing (CES) platforms targeting disease-related genes and enabling variant identification in patients with suspected genetic diseases. Nowadays, CES is rapidly becoming the diagnostic test of choice in patients with suspected Mendelian diseases, especially for those with heterogeneous etiology and clinical presentation. Reporting large CES series can improve guidelines on best practices for test utilization, and a better variant interpretation through clinically oriented data sharing.Herein, we suggest a feasible CES procedure for the genetic testing of Cerebral Cavernous Malformation (CCM) disease, including proband identification, library preparation, data analysis, and variant interpretation.

KRIT1 Deficiency Promotes Aortic Endothelial Dysfunction

Loss-of-function mutations of the gene encoding Krev interaction trapped protein 1 (KRIT1) are associated with the pathogenesis of Cerebral Cavernous Malformation (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries and affecting 0.5% of the human population. However, growing evidence demonstrates that KRIT1 is implicated in the modulation of major redox-sensitive signaling pathways and mechanisms involved in adaptive responses to oxidative stress and inflammation, suggesting that its loss-of-function mutations may have pathological effects not limited to CCM disease. The aim of this study was to address whether KRIT1 loss-of-function predisposes to the development of pathological conditions associated with enhanced endothelial cell susceptibility to oxidative stress and inflammation, such as arterial endothelial dysfunction (ED) and atherosclerosis. Silencing of KRIT1 in human aortic endothelial cells (HAECs), coronary artery endothelial cells (HCAECs), and umbilical vein endothelial cells (HUVECs) resulted in increased expression of endothelial proinflammatory adhesion molecules vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) and in enhanced susceptibility to tumor necrosis factor alpha (TNF-α)-induced apoptosis. These effects were associated with a downregulation of Notch1 activation that could be rescued by antioxidant treatment, suggesting that they are consequent to altered intracellular redox homeostasis induced by KRIT1 loss-of-function. Furthermore, analysis of the aorta of heterozygous KRIT1^+/- mice fed a high-fructose diet to induce systemic oxidative stress and inflammation demonstrated a 1.6-fold increased expression of VCAM-1 and an approximately 2-fold enhanced fat accumulation (7.5% vs 3.6%) in atherosclerosis-prone regions, including the aortic arch and aortic root, as compared to corresponding wild-type littermates. In conclusion, we found that KRIT1 deficiency promotes ED, suggesting that, besides CCM, KRIT1 may be implicated in genetic susceptibility to the development of atherosclerotic lesions.

KRIT1 Loss-Of-Function Associated with Cerebral Cavernous Malformation Disease Leads to Enhanced S-Glutathionylation of Distinct Structural and Regulatory Proteins

Loss-of-function mutations in the KRIT1 gene are associated with the pathogenesis of cerebral cavernous malformations (CCMs), a major cerebrovascular disease still awaiting therapies. Accumulating evidence demonstrates that KRIT1 plays an important role in major redox-sensitive mechanisms, including transcriptional pathways and autophagy, which play major roles in cellular homeostasis and defense against oxidative stress, raising the possibility that KRIT1 loss has pleiotropic effects on multiple redox-sensitive systems. Using previously established cellular models, we found that KRIT1 loss-of-function affects the glutathione (GSH) redox system, causing a significant decrease in total GSH levels and increase in oxidized glutathione disulfide (GSSG), with a consequent deficit in the GSH/GSSG redox ratio and GSH-mediated antioxidant capacity. Redox proteomic analyses showed that these effects are associated with increased S-glutathionylation of distinct proteins involved in adaptive responses to oxidative stress, including redox-sensitive chaperonins, metabolic enzymes, and cytoskeletal proteins, suggesting a novel molecular signature of KRIT1 loss-of-function. Besides providing further insights into the emerging pleiotropic functions of KRIT1, these findings point definitively to KRIT1 as a major player in redox biology, shedding new light on the mechanistic relationship between KRIT1 loss-of-function and enhanced cell sensitivity to oxidative stress, which may eventually lead to cellular dysfunctions and CCM disease pathogenesis.

Multifunctional Platinum@BSA-Rapamycin Nanocarriers for the Combinatorial Therapy of Cerebral Cavernous Malformation

Platinum nanoparticles (PtNPs) are antioxidant enzyme-mimetic nanomaterials with significant potential for the treatment of complex diseases related to oxidative stress. Among such diseases, Cerebral Cavernous Malformation (CCM) is a major cerebrovascular disorder of genetic origin, which affects at least 0.5% of the general population. Accumulated evidence indicates that loss-of-function mutations of the three known CCM genes predispose endothelial cells to oxidative stress-mediated dysfunctions by affecting distinct redox-sensitive signaling pathways and mechanisms, including pro-oxidant and antioxidant pathways and autophagy. A multitargeted combinatorial therapy might thereby represent a promising strategy for the effective treatment of this disease. Herein, we developed a multifunctional nanocarrier by combining the radical scavenging activity of PtNPs with the autophagy-stimulating activity of rapamycin (Rapa). Our results show that the combinatorial targeting of redox signaling and autophagy dysfunctions is effective in rescuing major molecular and cellular hallmarks of CCM disease, suggesting its potential for the treatment of this and other oxidative stress-related diseases.

A single-center study on 140 patients with cerebral cavernous malformations: 28 new pathogenic variants and functional characterization of a PDCD10 large deletion

Cerebral cavernous malformation (CCM) is a capillary malformation arising in the central nervous system. CCM may occur sporadically or cluster in families with autosomal dominant transmission, incomplete penetrance, and variable expressivity. Three genes are associated with CCM KRIT1, CCM2, and PDCD10. This work is a retrospective single-center molecular study on samples from multiple Italian clinical providers. From a pool of 317 CCM index patients, we found germline variants in either of the three genes in 80 (25.2%) probands, for a total of 55 different variants. In available families, extended molecular analysis found segregation in 60 additional subjects, for a total of 140 mutated individuals. From the 55 variants, 39 occurred in KRIT1 (20 novel), 8 in CCM2 (4 novel), and 8 in PDCD10 (4 novel). Effects of the three novel KRIT1 missense variants were characterized in silico. We also investigated a novel PDCD10 deletion spanning exon 4-10, on patient's fibroblasts, which showed significant reduction of interactions between KRIT1 and CCM2 encoded proteins and impaired autophagy process. This is the largest study in Italian CCM patients and expands the known mutational spectrum of KRIT1, CCM2, and PDCD10. Our approach highlights the relevance of seeking supporting information to pathogenicity of new variants for the improvement of management of CCM.

Biological Activities, Health Benefits, and Therapeutic Properties of Avenanthramides: From Skin Protection to Prevention and Treatment of Cerebrovascular Diseases

Oat (Avena sativa) is a cereal known since antiquity as a useful grain with abundant nutritional and health benefits. It contains distinct molecular components with high antioxidant activity, such as tocopherols, tocotrienols, and flavanoids. In addition, it is a unique source of avenanthramides, phenolic amides containing anthranilic acid and hydroxycinnamic acid moieties, and endowed with major beneficial health properties because of their antioxidant, anti-inflammatory, and antiproliferative effects. In this review, we report on the biological activities of avenanthramides and their derivatives, including analogs produced in recombinant yeast, with a major focus on the therapeutic potential of these secondary metabolites in the treatment of aging-related human diseases. Moreover, we also present recent advances pointing to avenanthramides as interesting therapeutic candidates for the treatment of cerebral cavernous malformation (CCM) disease, a major cerebrovascular disorder affecting up to 0.5% of the human population. Finally, we highlight the potential of foodomics and redox proteomics approaches in outlining distinctive molecular pathways and redox protein modifications associated with avenanthramide bioactivities in promoting human health and contrasting the onset and progression of various pathologies. The paper is dedicated to the memory of Adelia Frison.

The therapeutic potential of targeting the endothelial-to-mesenchymal transition

Endothelial cells (ECs) have been found to be capable of acquiring a mesenchymal phenotype through a process known as endothelial-to-mesenchymal transition (EndMT). First seen in the developing embryo, EndMT can be triggered postnatally under certain pathological conditions. During this process, ECs dedifferentiate into mesenchymal stem-like cells (MSCs) and subsequently give rise to cell types belonging to the mesoderm lineage. As EndMT contributes to a multitude of diseases, pharmacological modulation of the signaling pathways underlying EndMT may prove to be effective as a therapeutic treatment. Additionally, EndMT in ECs could also be exploited to acquire multipotent MSCs, which can be readily re-differentiated into various distinct cell types. In this review, we will consider current models of EndMT, how manipulation of this process might improve treatment of clinically important pathologies and how it could be harnessed to advance regenerative medicine and tissue engineering.

KRIT1 loss-of-function induces a chronic Nrf2-mediated adaptive homeostasis that sensitizes cells to oxidative stress: Implication for Cerebral Cavernous Malformation disease

KRIT1 (CCM1) is a disease gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease of proven genetic origin affecting 0.3-0.5% of the population. Previously, we demonstrated that KRIT1 loss-of-function is associated with altered redox homeostasis and abnormal activation of the redox-sensitive transcription factor c-Jun, which collectively result in pro-oxidative, pro-inflammatory and pro-angiogenic effects, suggesting a novel pathogenic mechanism for CCM disease and raising the possibility that KRIT1 loss-of-function exerts pleiotropic effects on multiple redox-sensitive mechanisms. To address this possibility, we investigated major redox-sensitive pathways and enzymatic systems that play critical roles in fundamental cytoprotective mechanisms of adaptive responses to oxidative stress, including the master Nrf2 antioxidant defense pathway and its downstream target Glyoxalase 1 (Glo1), a pivotal stress-responsive defense enzyme involved in cellular protection against glycative and oxidative stress through the metabolism of methylglyoxal (MG). This is a potent post-translational protein modifier that may either contribute to increased oxidative molecular damage and cellular susceptibility to apoptosis, or enhance the activity of major apoptosis-protective proteins, including heat shock proteins (Hsps), promoting cell survival. Experimental outcomes showed that KRIT1 loss-of-function induces a redox-sensitive sustained upregulation of Nrf2 and Glo1, and a drop in intracellular levels of MG-modified Hsp70 and Hsp27 proteins, leading to a chronic adaptive redox homeostasis that counteracts intrinsic oxidative stress but increases susceptibility to oxidative DNA damage and apoptosis, sensitizing cells to further oxidative challenges. While supporting and extending the pleiotropic functions of KRIT1, these findings shed new light on the mechanistic relationship between KRIT1 loss-of-function and enhanced cell predisposition to oxidative damage, thus providing valuable new insights into CCM pathogenesis and novel options for the development of preventive and therapeutic strategies.

Oxidative stress and inflammation in cerebral cavernous malformation disease pathogenesis: Two sides of the same coin

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CCM proteins play pleiotropic roles in various redox-sensitive signaling pathways.

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CCM proteins modulate the crosstalk between redox signaling and autophagy that govern cell homeostasis and stress responses.

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Oxidative stress and inflammation are emerging as key focal determinants of CCM lesion formation, progression and severity.

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The pleiotropic functions of CCM proteins may prevent vascular dysfunctions triggered by local oxidative stress and inflammatory events.

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The distinct therapeutic compounds proposed so far for CCM disease share the ability to modulate redox signaling and autophagy.

Cerebral Cavernous Malformation (CCM) is a vascular disease of proven genetic origin, which may arise sporadically or is inherited as an autosomal dominant condition with incomplete penetrance and highly variable expressivity. CCM lesions exhibit a range of different phenotypes, including wide inter-individual differences in lesion number, size, and susceptibility to intracerebral hemorrhage (ICH). Lesions may remain asymptomatic or result in pathological conditions of various type and severity at any age, with symptoms ranging from recurrent headaches to severe neurological deficits, seizures, and stroke. To date there are no direct therapeutic approaches for CCM disease besides the surgical removal of accessible lesions. Novel pharmacological strategies are particularly needed to limit disease progression and severity and prevent de novo formation of CCM lesions in susceptible individuals.

Useful insights into innovative approaches for CCM disease prevention and treatment are emerging from a growing understanding of the biological functions of the three known CCM proteins, CCM1/KRIT1, CCM2 and CCM3/PDCD10. In particular, accumulating evidence indicates that these proteins play major roles in distinct signaling pathways, including those involved in cellular responses to oxidative stress, inflammation and angiogenesis, pointing to pathophysiological mechanisms whereby the function of CCM proteins may be relevant in preventing vascular dysfunctions triggered by these events. Indeed, emerging findings demonstrate that the pleiotropic roles of CCM proteins reflect their critical capacity to modulate the fine-tuned crosstalk between redox signaling and autophagy that govern cell homeostasis and stress responses, providing a novel mechanistic scenario that reconciles both the multiple signaling pathways linked to CCM proteins and the distinct therapeutic approaches proposed so far. In addition, recent studies in CCM patient cohorts suggest that genetic susceptibility factors related to differences in vascular sensitivity to oxidative stress and inflammation contribute to inter-individual differences in CCM disease susceptibility and severity.

This review discusses recent progress into the understanding of the molecular basis and mechanisms of CCM disease pathogenesis, with specific emphasis on the potential contribution of altered cell responses to oxidative stress and inflammatory events occurring locally in the microvascular environment, and consequent implications for the development of novel, safe, and effective preventive and therapeutic strategies.