Cytochrome P4504f, a potential therapeutic target limiting neuroinflammation

"Lipopolysaccharide-induced animal models for neuroinflammation - An overview."

Neuroinflammation is a pathological mechanism contributing to neurodegenerative diseases. For in-depth studies of neuroinflammation, several animal models reported reproducing behavioral dysfunctions and cellular pathological mechanisms induced by brain inflammation. One of the most popular models of neuroinflammation is the one generated by lipopolysaccharide exposure. Despite its importance, the reported results using this model show high heterogeneity, making it difficult to analyze and compare the outcomes between studies. Therefore, the current review aims to summarize the different experimental paradigms used to reproduce neuroinflammation by lipopolysaccharide exposure and its respective outcomes, helping to choose the model that better suits each specific research aim.

Posttranslational Modification of Human Cytochrome CYP4F11 by 4-Hydroxynonenal Impairs ω-Hydroxylation in Malaria Pigment Hemozoin-Fed Monocytes: The Role in Malaria Immunosuppression

Malaria is a frequent parasitic infection becomes life threatening due to the disequilibrated immune responses of the host. Avid phagocytosis of malarial pigment hemozoin (HZ) and HZ-containing Plasmodium parasites incapacitates monocyte functions by bioactive lipoperoxidation products 4-hydroxynonenal (4-HNE) and hydroxyeicosatetraenoic acids (HETEs). CYP4F conjugation with 4-HNE is hypothesised to inhibit ω-hydroxylation of 15-HETE, leading to sustained monocyte dysfunction caused by 15-HETE accumulation. A combined immunochemical and mass-spectrometric approach identified 4-HNE-conjugated CYP4F11 in primary human HZ-laden and 4-HNE-treated monocytes. Six distinct 4-HNE-modified amino acid residues were revealed, of which C260 and H261 are localized in the substrate recognition site of CYP4F11. Functional consequences of enzyme modification were investigated on purified human CYP4F11. Palmitic acid, arachidonic acid, 12-HETE, and 15-HETE bound to unconjugated CYP4F11 with apparent dissociation constants of 52, 98, 38, and 73 µM, respectively, while in vitro conjugation with 4-HNE completely blocked substrate binding and enzymatic activity of CYP4F11. Gas chromatographic product profiles confirmed that unmodified CYP4F11 catalysed the ω-hydroxylation while 4-HNE-conjugated CYP4F11 did not. The 15-HETE dose dependently recapitulated the inhibition of the oxidative burst and dendritic cell differentiation by HZ. The inhibition of CYP4F11 by 4-HNE with consequent accumulation of 15-HETE is supposed to be a crucial step in immune suppression in monocytes and immune imbalance in malaria.

Regulation of Human Endogenous Metabolites by Drug Transporters and Drug Metabolizing Enzymes: An Analysis of Targeted SNP-Metabolite Associations

Drug transporters and drug-metabolizing enzymes are primarily known for their role in the absorption, distribution, metabolism, and excretion (ADME) of small molecule drugs, but they also play a key role in handling endogenous metabolites. Recent cross-tissue co-expression network analyses have revealed a "Remote Sensing and Signaling Network" of multispecific, oligo-specific, and monospecific transporters and enzymes involved in endogenous metabolism. This includes many proteins from families involved in ADME (e.g., SLC22, SLCO, ABCC, CYP, UGT). Focusing on the gut-liver-kidney axis, we identified the endogenous metabolites potentially regulated by this network of ~1000 proteins by associating SNPs in these genes with the circulating levels of thousands of small, polar, bioactive metabolites, including free fatty acids, eicosanoids, bile acids, and other signaling metabolites that act in part via G-protein coupled receptors (GPCRs), nuclear receptors, and kinases. We identified 77 genomic loci associated with 7236 unique metabolites. This included metabolites that were associated with multiple, distinct loci, indicating coordinated regulation between multiple genes (including drug transporters and drug-metabolizing enzymes) of specific metabolites. We analyzed existing pharmacogenomic data and noted SNPs implicated in endogenous metabolite handling (e.g., rs4149056 in SLCO1B1) also affecting drug ADME. The overall results support the existence of close relationships, via interactions with signaling metabolites, between drug transporters and drug-metabolizing enzymes that are part of the Remote Sensing and Signaling Network, and with GPCRs and nuclear receptors. These analyses highlight the potential for drug-metabolite interactions at the interfaces of the Remote Sensing and Signaling Network and the ADME protein network.

Relationship of familial cytochrome P450 4V2 gene mutation with liver cirrhosis: A case report and review of the literature

BACKGROUND

Many genetic and metabolic diseases affect the liver, but diagnosis can be difficult because these diseases may have complex clinical manifestations and diverse clinical patterns. There is also incomplete clinical knowledge of these many different diseases and limitations of current testing methods.

CASE SUMMARY

We report a 53-year-old female from a rural area in China who was hospitalized for lower limb edema, abdominal distension, cirrhosis, and hypothyroidism. We excluded the common causes of liver disease (drinking alcohol, using traditional Chinese medicines, hepatitis virus infection, autoimmunity, and hepatolenticular degeneration). When she was 23-years-old, she developed night-blindness that worsened to complete blindness, with no obvious cause. Her parents were first cousins, and both were alive. Analysis of the patient’s family history indicated that all 5 siblings had night blindness and impaired vision; one sister was completely blind; and another sister had night-blindness complicated with cirrhosis and subclinical hypothyroidism. Entire exome sequencing showed that the patient, parents, and siblings all had mutations in the cytochrome P450 4V2 gene (CYP4V2). The CYP4V2 mutations of the parents and two sisters were heterozygous, and the others were homozygous. Two siblings also had heterozygous dual oxidase activator 2 (DUOXA2) mutations.

CONCLUSION

Mutations in the CYP4V2 gene may affect lipid metabolism and lead to chronic liver injury, fibrosis, and cirrhosis.

Rosmarinic acid relieves LPS-induced sickness and depressive-like behaviors in mice by activating the BDNF/Nrf2 signaling and autophagy pathway

Neuroinflammation is one of the main causes of sickness and depressive-like behavior. Rosmarinic acid (RA) has been shown to have a significant anti-neuroinflammatory effect. However, the protective effects and the underlying mechanism of RA on sickness and depressive-like behavior under conditions of neuroinflammation are still unclear.　In the present study,　we investigated the effects and　the underlying mechanism of RA on lipopolysaccharide (LPS)-treated mice with sickness behavior. The behavioral effects of LPS treatment and RA administration were assessed using behavioral tests including a sucrose preference test and an open field test. The neuroprotective effects of RA in conditions of neuroinflammatory injury were determined by HE staining, Nissl staining, and immunofluorescent staining. Moreover, its underlying mechanism was analyzed by using real-time PCR analysis, western blot, and immunofluorescent analysis. The results indicated that RA dramatically mitigated sickness behaviors and histologic brain damage in mice exposed to LPS. In addition, RA administration markedly promoted the expression of brain-derived neurotrophic factor (BDNF)/erythroid 2-related factor 2 (Nrf2), the key regulatory proteins for Nrf2 activation (p21 and p62), the downstream antioxidant enzymes (HO-1, NQO1, GCLC), the autophagy-related proteins (LC3II and Beclin1), and mitochondrial respiratory enzyme genes (ME1, IDH1, 6-PGDH), while reducing the expression of pro-inflammatory genes (CD44, iNOS, TNFα, IL-1β). Moreover, the double-label immunofluorescent analysis revealed that RA increased the fluorescence intensity of LC3 mostly co-localized with neurons and co-expressed with Nrf2. Taken together, our research found that RA could effectively alleviate sickness behaviors and nerve injury caused by neuroinflammation, and its protective effects were mediated by the Nrf2 signaling pathway, which reduced cellular oxidative stress, inflammation, mitochondrial respiratory function damage, and autophagy imbalance. Therefore, RA has the potential to prevent or treat sickness and depressive-like behaviors under conditions of neuroinflammation.

Maternal high-fat diet in mice induces cerebrovascular, microglial and long-term behavioural alterations in offspring

Various environmental exposures during pregnancy, like maternal diet, can compromise, at critical periods of development, the neurovascular maturation of the offspring. Foetal exposure to maternal high-fat diet (mHFD), common to Western societies, has been shown to disturb neurovascular development in neonates and long-term permeability of the neurovasculature. Nevertheless, the effects of mHFD on the offspring’s cerebrovascular health remains largely elusive. Here, we sought to address this knowledge gap by using a translational mouse model of mHFD exposure. Three-dimensional and ultrastructure analysis of the neurovascular unit (vasculature and parenchymal cells) in mHFD-exposed offspring revealed major alterations of the neurovascular organization and metabolism. These alterations were accompanied by changes in the expression of genes involved in metabolism and immunity, indicating that neurovascular changes may result from abnormal brain metabolism and immune regulation. In addition, mHFD-exposed offspring showed persisting behavioural alterations reminiscent of neurodevelopmental disorders, specifically an increase in stereotyped and repetitive behaviours into adulthood.

In order to advance our understanding of the effects of maternal high-fat diet (mHFD) on the cerebrovascular health of offspring, Bordeleau et al. use a translational mouse model of mHFD exposure. They demonstrate that mHFD induces cerebrovascular and microglial changes in the offspring as well as behavioural alterations that are reminiscent of neurodevelopmental disorders associated with repetitive behaviours at adulthood.

Polymorphisms in genes related to oxidative stress and inflammation: Emerging links with the pathogenesis and severity of Cerebral Cavernous Malformation disease

Cerebral Cavernous Malformation (CCM) is a cerebrovascular disease of genetic origin affecting 0.5% of the population and characterized by abnormally enlarged and leaky capillaries that predispose to seizures, neurological deficits, and intracerebral hemorrhage (ICH). CCM occurs sporadically or is inherited as dominant condition with incomplete penetrance and highly variable expressivity. Three disease genes have been identified: KRIT1 (CCM1), CCM2 and CCM3. Previous results demonstrated that loss-of-function mutations of CCM genes cause pleiotropic effects, including defective autophagy, altered reactive oxygen species (ROS) homeostasis, and enhanced sensitivity to oxidative stress and inflammatory events, suggesting a novel unifying pathogenetic mechanism, and raising the possibility that CCM disease onset and severity are influenced by the presence of susceptibility and modifier genes. Consistently, genome-wide association studies (GWAS) in large and homogeneous cohorts of patients sharing the familial form of CCM disease and identical mutations in CCM genes have led to the discovery of distinct genetic modifiers of major disease severity phenotypes, such as development of numerous and large CCM lesions, and susceptibility to ICH. This review deals with the identification of genetic modifiers with a significant impact on inter-individual variability in CCM disease onset and severity, including highly polymorphic genes involved in oxidative stress, inflammatory and immune responses, such as cytochrome P450 monooxygenases (CYP), matrix metalloproteinases (MMP), and Toll-like receptors (TLR), pointing to their emerging prognostic value, and opening up new perspectives for risk stratification and personalized medicine strategies.

Adipocyte-specific deletion of HuR induces spontaneous cardiac hypertrophy and fibrosis

Adipose tissue homeostasis plays a central role in cardiovascular physiology, and the presence of thermogenically active brown adipose tissue (BAT) has recently been associated with cardiometabolic health. We have previously shown that adipose tissue-specific deletion of HuR (Adipo-HuR^-/-) reduces BAT-mediated adaptive thermogenesis, and the goal of this work was to identify the cardiovascular impacts of Adipo-HuR^-/-. We found that Adipo-HuR^-/- mice exhibit a hypercontractile phenotype that is accompanied by increased left ventricle wall thickness and hypertrophic gene expression. Furthermore, hearts from Adipo-HuR^-/- mice display increased fibrosis via picrosirius red staining and periostin expression. To identify underlying mechanisms, we applied both RNA-seq and weighted gene coexpression network analysis (WGCNA) across both cardiac and adipose tissue to define HuR-dependent changes in gene expression as well as significant relationships between adipose tissue gene expression and cardiac fibrosis. RNA-seq results demonstrated a significant increase in proinflammatory gene expression in both cardiac and subcutaneous white adipose tissue (scWAT) from Adipo-HuR^-/- mice that is accompanied by an increase in serum levels of both TNF-α and IL-6. In addition to inflammation-related genes, WGCNA identified a significant enrichment in extracellular vesicle-mediated transport and exosome-associated genes in scWAT, whose expression most significantly associated with the degree of cardiac fibrosis observed in Adipo-HuR^-/- mice, implicating these processes as a likely adipose-to-cardiac paracrine mechanism. These results are significant in that they demonstrate the spontaneous onset of cardiovascular pathology in an adipose tissue-specific gene deletion model and contribute to our understanding of how disruptions in adipose tissue homeostasis may mediate cardiovascular disease.NEW & NOTEWORTHY The presence of functional brown adipose tissue in humans is known to be associated with cardiovascular health. Here, we show that adipocyte-specific deletion of the RNA binding protein HuR, which we have previously shown to reduce BAT-mediated thermogenesis, is sufficient to mediate a spontaneous development of cardiac hypertrophy and fibrosis. These results may have implications on the mechanisms by which BAT function and adipose tissue homeostasis directly mediate cardiovascular disease.

Regulation of cytochrome P450 4F11 expression by liver X receptor alpha

Cytochrome P450 4F (CYP4F) enzymes are responsible for the metabolism of eicosanoids, which play important roles in inflammation. Nuclear receptor liver X receptor alpha (LXRα) is a critical signal node connecting inflammation and lipid metabolism. Studies revealed that the release of cytokines and nuclear factor-κB (NF-κB) can change the CYP4F11 expression in HepG2 cells. However, the effect of LXRα on the CYP4F family and the underlying mechanism remain unclear. This study found that CYP4F11 is a target gene of LXRα. Luciferase assays and siRNA transfection showed that LXRα increased the transcription of CYP4F11 and LXRα agonist GW3965 could induce the expression of CYP4F11 by activating the LXRα-CYP4F11 pathway. Besides, overexpression of CYP4F11 could decrease TNF-α and IL-1β in lipopolysaccharide (LPS)-induced THP-1 cells. The finding of the regulation of CYP4F11 may contribute to the anti-inflammatory activity of LXRα agonists.

Targeting CYP2J2 to Enhance the Anti-Glioma Efficacy of Cannabinoid Receptor 2 Stimulation by Inhibiting the Pro-Angiogenesis Function of M2 Microglia

Enhancing the therapeutic efficacy of anti-tumor drugs is essential for cancer management. Although cannabinoid receptor 2 (CB2R) stimulation exerts anti-tumor action in glioma cells by regulating cellular proliferation, differentiation, or apoptosis, selective CB2R agonist alone does not achieve a satisfactory therapeutic outcome. Herein, we aimed to evaluate the possible strategy for enhancing the anti-glioma efficacy of JWH133, a selective CB2R agonist. In this study, immunofluorescence and qRT-PCR were used to investigate microglia polarization. Tumor growth was monitored via bioluminescent imaging using the IVIS Spectrum System. The angiogenesis of human brain microvascular endothelial cells (HBMECs) was detected by the tube formation assay. qRT-PCR was used to investigate cytochrome P450 2J2 (CYP2J2) and 11,12-epoxyeicosatrienoic acid (11,12-EET) expression. Our results showed that administration of JWH133 significantly promoted microglial M2 polarization both in vitro and in vivo. The medium supernatant of M2 microglia induced by JWH133 treatment facilitated angiogenesis of HBMECs. CYP2J2 expression and 11,12-EET release in the supernatant of JWH133-induced M2 microglia were significantly upregulated. Treatment with 11,12-EET prompted HBMEC angiogenesis and glioma growth. CYP2J2 knockdown restrained the release of 11,12-EET and significantly enhanced the anti-tumor effect of JWH133 on glioma. This study showed that targeting CYP2J2 might be a beneficial strategy to enhance the anti-glioma efficacy of JWH133 by inhibiting the pro-angiogenesis function of M2 microglia.

Farnesoid X receptor activation induces the degradation of hepatotoxic 1-deoxysphingolipids in non-alcoholic fatty liver disease

BACKGROUND & AIMS

Patients with non-alcoholic fatty liver disease (NAFLD) exhibit higher levels of plasma 1-deoxysphingolipids than healthy individuals. The aim of this study was to investigate the role of farnesoid X receptor (FXR) in 1-deoxysphingolipid de novo synthesis and degradation.

METHODS

Mice were fed with a high-fat diet (HFD) to induce obesity and NAFLD, and then treated with the FXR ligand obeticholic acid (OCA). Histology and gene expression analysis were performed on liver tissue. Sphingolipid patterns from NAFLD patients and mouse models were assessed by liquid chromatography-mass spectrometry. The molecular mechanism underlying the effect of FXR activation on sphingolipid metabolism was studied in Huh7 cells and primary cultured hepatocytes, as well as in a 1-deoxysphinganine-treated mouse model.

RESULTS

1-deoxysphingolipids were increased in both NAFLD patients and mouse models. FXR activation by OCA protected the liver against oxidative stress, apoptosis, and reduced 1-deoxysphingolipid levels, both in a HFD-induced mouse model of obesity and in 1-deoxysphinganine-treated mice. In vitro, FXR activation lowered intracellular 1-deoxysphingolipid levels by inducing Cyp4f-mediated degradation, but not by inhibiting de novo synthesis, thereby protecting hepatocytes against doxSA-induced cytotoxicity, mitochondrial damage, and apoptosis. Overexpression of Cyp4f13 in cells was sufficient to ameliorate doxSA-induced cytotoxicity. Treatment with the Cyp4f pan-inhibitor HET0016 or FXR knock-down fully abolished the protective effect of OCA, indicating that OCA-mediated 1-deoxysphingolipid degradation is FXR and Cyp4f dependent.

CONCLUSIONS

Our study identifies FXR-Cyp4f as a novel regulatory pathway for 1-deoxysphingolipid metabolism. FXR activation represents a promising therapeutic strategy for patients with metabolic syndrome and NAFLD.

Eicosanoids derived from cytochrome P450 pathway of arachidonic acid and inflammatory shock

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Septic shock, the most common form of vasodilatory shock, is a subset of sepsis in which circulatory and cellular/metabolic abnormalities are severe enough to increase mortality. Inflammatory shock constitutes the hallmark of sepsis, but also a final common pathway of any form of severe long-term tissue hypoperfusion. The pathogenesis of inflammatory shock seems to be due to circulating substances released by pathogens (e.g., bacterial endotoxins) and host immuno-inflammatory responses (e.g., changes in the production of histamine, bradykinin, serotonin, nitric oxide [NO], reactive nitrogen and oxygen species, and arachidonic acid [AA]-derived eicosanoids mainly through NO synthase, cyclooxygenase, and cytochrome P450 [CYP] pathways, and proinflammatory cytokine formation). Therefore, refractory hypotension to vasoconstrictors with end-organ hypoperfusion is a life threatening feature of inflammatory shock. This review summarizes the current knowledge regarding the role of eicosanoids derived from CYP pathway of AA in animal models of inflammatory shock syndromes with an emphasis on septic shock in addition to potential therapeutic strategies targeting specific CYP isoforms responsible for proinflammatory/anti-inflammatory mediator production.

Thromboxane A2 receptor antagonist SQ29548 suppresses the LPS‑induced release of inflammatory cytokines in BV2 microglia cells via suppressing MAPK and NF‑κB signaling pathways

Inflammation in the brain, characterized by the activation of microglia, is hypothesized to participate in the pathogenesis of neuronal disorders. It is proposed that thromboxane A2 receptor (TXA2R) activation is involved in thrombosis/hemostasis and inflammation responses. In the present study, the anti‑inflammatory effects of SQ29548 on lipopolysaccharide (LPS)‑stimulated BV2 microglial cells and its molecular mechanisms were investigated. In the BV2 cell line, LPS‑stimulated nitric oxide (NO) and inflammatory cytokine release, and the phosphorylation of mitogen‑activated protein kinases (MAPKs) and the nuclear factor (NF)‑κB were assessed using an NO assay kit, reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. In vitro studies demonstrated that SQ29548 inhibited LPS‑stimulated BV2 activation and reduced the mRNA expression levels of interleukin (IL)‑1β, IL‑6, tumor necrosis factor‑α and inducible NO synthase via inhibition of MAPKs and the NF‑κB signaling pathway. SQ29548 inhibited the LPS‑induced inflammatory response by blocking MAPKs and NF‑κB activation in BV2 microglial cells.

Cytotoxic 1-deoxysphingolipids are metabolized by a cytochrome P450-dependent pathway

The 1-deoxysphingolipids (1-deoxySLs) are atypical sphingolipids (SLs) that are formed when serine palmitoyltransferase condenses palmitoyl-CoA with alanine instead of serine during SL synthesis. The 1-deoxySLs are toxic to neurons and pancreatic β-cells. Pathologically elevated 1-deoxySLs cause the inherited neuropathy, hereditary sensory autonomic neuropathy type 1 (HSAN1), and are also found in T2D. Diabetic sensory polyneuropathy (DSN) and HSAN1 are clinically very similar, suggesting that 1-deoxySLs may be implicated in both pathologies. The 1-deoxySLs are considered to be dead-end metabolites, as they lack the C1-hydroxyl group, which is essential for the canonical degradation of SLs. Here, we report a previously unknown metabolic pathway, which is capable of degrading 1-deoxySLs. Using a variety of metabolic labeling approaches and high-resolution high-accuracy MS, we identified eight 1-deoxySL downstream metabolites, which appear to be formed by cytochrome P450 (CYP)4F enzymes. Comprehensive inhibition and induction of CYP4F enzymes blocked and stimulated, respectively, the formation of the downstream metabolites. Consequently, CYP4F enzymes might be novel therapeutic targets for the treatment of HSAN1 and DSN, as well as for the prevention of T2D.

Thromboxane A2 receptor antagonist SQ29548 reduces ischemic stroke-induced microglia/macrophages activation and enrichment, and ameliorates brain injury

Thromboxane A2 receptor (TXA2R) activation is thought to be involved in thrombosis/hemostasis and inflammation responses. We have previously shown that TXA2R antagonist SQ29548 attenuates BV2 microglia activation by suppression of ERK pathway, but its effect is not tested in vivo. The present study aims to explore the role of TXA2R on microglia/macrophages activation after ischemia/reperfusion brain injury in mice. Adult male ICR mice underwent 90-min transient middle cerebral artery occlusion (tMCAO). Immediately and 24 h after reperfusion, SQ29548 was administered twice to the ipsilateral ventricle (10 μl, 2.6 μmol/ml, per dose). Cerebral infarction volume, inflammatory cytokines release and microglia/macrophages activation were measured using the cresyl violet method, quantitative polymerase chain reaction (qPCR), and immunofluorescence double staining, respectively. Expression of TXA2R was significantly increased in the ipsilateral brain tissue after ischemia/reperfusion, which was also found to co-localize with activated microglia/macrophages in the infarct area. Administration of SQ29548 inhibited microglia/macrophages activation and enrichment, including both M1 and M2 phenotypes, and attenuated ischemia-induced IL-1ß, IL-6, and TNF-α up-regulation and iNOS release. TXA2R antagonist SQ29548 inhibited ischemia-induced inflammatory response and furthermore reduced microglia/macrophages activation and ischemic/reperfusion brain injury.

Molecular mechanisms and cell signaling of 20-hydroxyeicosatetraenoic acid in vascular pathophysiology

Cytochrome P450s enzymes catalyze the metabolism of arachidonic acid to epoxyeicosatrienoic acids (EETs), dihydroxyeicosatetraenoic acid and hydroxyeicosatetraeonic acid (HETEs). 20-HETE is a vasoconstrictor that depolarizes vascular smooth muscle cells by blocking K+ channels. EETs serve as endothelial derived hyperpolarizing factors. Inhibition of the formation of 20-HETE impairs the myogenic response and autoregulation of renal and cerebral blood flow. Changes in the formation of EETs and 20-HETE have been reported in hypertension and drugs that target these pathways alter blood pressure in animal models. Sequence variants in CYP4A11 and CYP4F2 that produce 20-HETE, UDP-glucuronosyl transferase involved in the biotransformation of 20-HETE and soluble epoxide hydrolase that inactivates EETs are associated with hypertension in human studies. 20-HETE contributes to the regulation of vascular hypertrophy, restenosis, angiogenesis and inflammation. It also promotes endothelial dysfunction and contributes to cerebral vasospasm and ischemia-reperfusion injury in the brain, kidney and heart. This review will focus on the role of 20-HETE in vascular dysfunction, inflammation, ischemic and hemorrhagic stroke and cardiac and renal ischemia reperfusion injury.

Cytochrome P450 and matrix metalloproteinase genetic modifiers of disease severity in Cerebral Cavernous Malformation type 1

BACKGROUND

Familial Cerebral Cavernous Malformation type 1 (CCM1) is an autosomal dominant disease caused by mutations in the Krev Interaction Trapped 1 (KRIT1/CCM1) gene, and characterized by multiple brain lesions. CCM lesions manifest across a range of different phenotypes, including wide differences in lesion number, size and susceptibility to intracerebral hemorrhage (ICH). Oxidative stress plays an important role in cerebrovascular disease pathogenesis, raising the possibility that inter-individual variability in genes related to oxidative stress may contribute to the phenotypic differences observed in CCM1 disease. Here, we investigated whether candidate oxidative stress-related cytochrome P450 (CYP) and matrix metalloproteinase (MMP) genetic markers grouped by superfamilies, families or genes, or analyzed individually influence the severity of CCM1 disease.

METHODS

Clinical assessment and cerebral susceptibility-weighted magnetic resonance imaging (SWI) were performed to determine total and large (≥5mm in diameter) lesion counts as well as ICH in 188 Hispanic CCM1 patients harboring the founder KRIT1/CCM1 'common Hispanic mutation' (CCM1-CHM). Samples were genotyped on the Affymetrix Axiom Genome-Wide LAT1 Human Array. We analyzed 1,122 genetic markers (both single nucleotide polymorphisms (SNPs) and insertion/deletions) grouped by CYP and MMP superfamily, family or gene for association with total or large lesion count and ICH adjusted for age at enrollment and gender. Genetic markers bearing the associations were then analyzed individually.

RESULTS

The CYP superfamily showed a trend toward association with total lesion count (P=0.057) and large lesion count (P=0.088) in contrast to the MMP superfamily. The CYP4 and CYP8 families were associated with either large lesion count or total lesion count (P=0.014), and two other families (CYP46 and the MMP Stromelysins) were associated with ICH (P=0.011 and 0.007, respectively). CYP4F12 rs11085971, CYP8A1 rs5628, CYP46A1 rs10151332, and MMP3 rs117153070 single SNPs, mainly bearing the above-mentioned associations, were also individually associated with CCM1 disease severity.

CONCLUSIONS

Overall, our candidate oxidative stress-related genetic markers set approach outlined CYP and MMP families and identified suggestive SNPs that may impact the severity of CCM1 disease, including the development of numerous and large CCM lesions and ICH. These novel genetic risk factors of prognostic value could serve as early objective predictors of disease outcome and might ultimately provide better options for disease prevention and treatment.

Sleep and immunomodulatory responses to systemic lipopolysaccharide in mice selectively expressing interleukin-1 receptor 1 on neurons or astrocytes

Sleep-wake behavior is altered in response to immune challenge. Although the precise mechanisms that govern sickness-induced changes in sleep are not fully understood, interleukin-1β (IL-1) is one mediator of these responses. To better understand mechanisms underlying sleep and inflammatory responses to immune challenge, we used two transgenic mouse strains that express IL-1 receptor 1 (IL1R1) only in the central nervous system and selectively on neurons or astrocytes. Electroencephalographic recordings from transgenic and wild-type mice reveal that systemic challenge with lipopolysaccharide (LPS) fragments sleep, suppresses rapid eye movement sleep (REMS), increases non-REMS (NREMS), diminishes NREM delta power, and induces fever in all genotypes. However, the magnitude of REMS suppression is greater in mice expressing IL1R1 on astrocytes compared with mice in which IL1R1 is selectively expressed on neurons. Furthermore, there is a delayed increase in NREM delta power when IL1R1 is expressed on astrocytes. LPS-induced sleep fragmentation is reduced in mice expressing IL1R1 on neurons. Although LPS increases IL-1 and IL-6 in brain of all genotypes, this response is attenuated when IL1R1 is expressed selectively on neurons or on astrocytes. Collectively, these data suggest that in these transgenic mice under the conditions of this study it is neuronal IL1R1 that plays a greater role in LPS-induced suppression of REMS and NREM delta power, whereas astroglial IL1R1 is more important for sleep fragmentation after this immune challenge. Thus, aspects of central responses to LPS are modulated by IL1R1 in a cell type-specific manner.

CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a

CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.9-2.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies.

Sequential oxidation of Jasmonoyl-Phenylalanine and Jasmonoyl-Isoleucine by multiple cytochrome P450 of the CYP94 family through newly identified aldehyde intermediates

The role and fate of Jasmonoyl-Phenylalanine (JA-Phe), an understudied conjugate in the jasmonate pathway remain to be unraveled. We addressed here the possibility of JA-Phe oxidative turnover by cytochrome P450s of the CYP94 family. Leaf wounding or fungal infection in Arabidopsis resulted in accumulation of JA-Phe, 12-hydroxyl (12OH-JA-Phe) and 12-carboxyl (12COOH-JA-Phe) derivatives, with patterns differing from those previously described for Jasmonoyl-Isoleucine. In vitro, yeast-expressed cytochromes P450 CYP94B1, CYP94B3 and CYP94C1 differentially oxidized JA-Phe to 12-hydroxyl, 12-aldehyde and 12-carboxyl derivatives. Furthermore, a new aldehyde jasmonate, 12CHO-JA-Ile was detected in wounded plants. Metabolic analysis of CYP94B3 and CYP94C1 loss- and gain-of-function plant lines showed that 12OH-JA-Phe was drastically reduced in cyp94b3 but not affected in cyp94c1, while single or double mutants lacking CYP94C1 accumulated less 12COOH-JA-Phe than WT plants. This, along with overexpressing lines, demonstrates that hydroxylation by CYP94B3 and carboxylation by CYP94C1 accounts for JA-Phe turnover in planta. Evolutionary study of the CYP94 family in the plant kingdom suggests conserved roles of its members in JA conjugate homeostasis and possibly in adaptative functions. Our work extends the range and complexity of JA-amino acid oxidation by multifunctional CYP94 enzymes in response to environmental cues.

Cytochrome P450 ω-Hydroxylases in Inflammation and Cancer

Cytochrome P450-dependent ω-hydroxylation is a prototypic metabolic reaction of CYP4 family members that is important for the elimination and bioactivation of not only therapeutic drugs, but also endogenous compounds, principally fatty acids. Eicosanoids, derived from arachidonic acid, are key substrates in the latter category. Human CYP4 enzymes, mainly CYP4A11, CYP4F2, and CYP4F3B, hydroxylate arachidonic acid at the omega position to form 20-HETE, which has important effects in tumor progression and on angiogenesis and blood pressure regulation in the vasculature and kidney. CYP4F3A in myeloid tissue catalyzes the ω-hydroxylation of leukotriene B4 to 20-hydroxy leukotriene B4, an inactivation process that is critical for the regulation of the inflammatory response. Here, we review the enzymology, tissue distribution, and substrate selectivity of human CYP4 ω-hydroxylases and their roles as catalysts for the formation and termination of the biological effects of key eicosanoid metabolites in inflammation and cancer progression.

Systemic inflammation and microglial activation: systematic review of animal experiments

Background

Animal studies show that peripheral inflammatory stimuli may activate microglial cells in the brain implicating an important role for microglia in sepsis-associated delirium. We systematically reviewed animal experiments related to the effects of systemic inflammation on the microglial and inflammatory response in the brain.

Methods

We searched PubMed between January 1, 1950 and December 1, 2013 and Embase between January 1, 1988 and December 1, 2013 for animal studies on the influence of peripheral inflammatory stimuli on microglia and the brain. Identified studies were systematically scored on methodological quality. Two investigators extracted independently data on animal species, gender, age, and genetic background; number of animals; infectious stimulus; microglial cells; and other inflammatory parameters in the brain, including methods, time points after inoculation, and brain regions.

Results

Fifty-one studies were identified of which the majority was performed in mice (n = 30) or in rats (n = 19). Lipopolysaccharide (LPS) (dose ranging between 0.33 and 200 mg/kg) was used as a peripheral infectious stimulus in 39 studies (76 %), and live or heat-killed pathogens were used in 12 studies (24 %). Information about animal characteristics such as species, strain, sex, age, and weight were defined in 41 studies (80 %), and complete methods of the disease model were described in 35 studies (68 %). Studies were also heterogeneous with respect to methods used to assess microglial activation; markers used mostly were the ionized calcium binding adaptor molecule-1 (Iba-1), cluster of differentiation 68 (CD68), and CD11b. After LPS challenge microglial activation was seen 6 h after challenge and remained present for at least 3 days. Live Escherichia coli resulted in microglial activation after 2 days, and heat-killed bacteria after 2 weeks. Concomitant with microglial response, inflammatory parameters in the brain were reviewed in 23 of 51 studies (45 %). Microglial activation was associated with an increase in Toll-like receptor (TLR-2 and TLR-4), tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) messenger ribonucleic acid (mRNA) expression or protein levels.

Interpretation

Animal experiments robustly showed that peripheral inflammatory stimuli cause microglial activation. We observed distinct differences in microglial activation between systemic stimulation with (supranatural doses) LPS and live or heat-killed bacteria.

The revised human liver cytochrome P450 "Pie": absolute protein quantification of CYP4F and CYP3A enzymes using targeted quantitative proteomics

The CYP4F subfamily of enzymes has been identified recently to be involved in the metabolism of endogenous compounds (arachidonic acid and leukotriene B4), nutrients (vitamins K1 and E), and xenobiotics (pafuramidine and fingolimod). CYP4F2 and CYP4F3B are reported to be expressed in the human liver. However, absolute concentrations of these enzymes in human liver microsomes (HLMs) and their interindividual variability have yet to be determined because of the lack of specific antibodies. Here, an liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based targeted quantitative proteomic approach was employed to determine the absolute protein concentrations of CYP4F2 and CYP4F3B compared with CYP3A in two panels of HLMs (n = 31). As a result, the human hepatic cytochrome P450 (P450) "pie" has been revised to include the contribution of CYP4F enzymes, which amounts to 15% of the total hepatic cytochrome P450 enzymes. CYP4F3B displayed low interindividual variability (3.3-fold) in the HLM panels whereas CYP4F2 displayed large variability (21-fold). However, CYP4F2 variability decreased to 3.4-fold if the two donors with the lowest expression were excluded. In contrast, CYP3A exhibited 29-fold interindividual variability in the same HLM panels. The proposed marker reaction for CYP4F enzymes pafuramidine/DB289 M1 formation did not correlate with CYP4F protein content, suggesting alternate metabolic pathways for DB289 M1 formation in HLMs. In conclusion, CYP4F enzymes are highly expressed in the human liver and their physiologic and pharmacologic roles warrant further investigation.

Cytochrome P450-mediated metabolism in brain: functional roles and their implications

INTRODUCTION

Cytochromes P450 (P450) and associated monooxygenases are a family of heme proteins involved in metabolism of endogenous compounds (arachidonic acid, eicosanoids and prostaglandins) as also xenobiotics including drugs and environmental chemicals. Liver is the major organ involved in P450-mediated metabolism and hepatic enzymes have been characterized. Extrahepatic organs, such as lung, kidney and brain have the capability for biotransformation through P450 enzymes. Brain, including human brain, expresses P450 enzymes that metabolize xenobiotics and endogenous compounds.

AREAS COVERED

An overview of P450-mediated metabolism in brain is presented focusing on distinct differences seen in expression of P450 enzymes, generation of unique P450 enzymes in brain through alternate splicing and their consequences in terms of metabolism of psychoactive drugs and inflammatory prompts, such as leukotrienes, thus modulating inflammatory response.

EXPERT OPINION

The brain possesses unique P450s that metabolize drugs and endogenous compounds through pathways that are markedly different from that seen in liver indicating that extrapolation directly from liver to brain is not appropriate. It is therefore necessary to characterize the unique brain P450s and their ability to metabolize xenobiotics and endogenous compounds to better understand the functions of this important class of enzymes in brain, especially human brain.

Increase of 20-HETE synthase after brain ischemia in rats revealed by PET study with 11C-labeled 20-HETE synthase-specific inhibitor

20-Hydroxyeicosatetraenoic acid (20-HETE), an arachidonic acid metabolite known to be produced after cerebral ischemia, has been implicated in ischemic and reperfusion injury by mediating vasoconstriction. To develop a positron emission tomography (PET) probe for 20-HETE synthase imaging, which might be useful for monitoring vasoconstrictive processes in patients with brain ischemia, we synthesized a (11)C-labeled specific 20-HETE synthase inhibitor, N'(4-dimethylaminohexyloxy)phenyl imidazole ([(11)C]TROA). Autoradiographic study showed that [(11)C]TROA has high-specific binding in the kidney and liver consistent with the previously reported distribution of 20-HETE synthase. Using transient middle cerebral artery occlusion in rats, PET study showed significant increases in the binding of [(11)C]TROA in the ipsilateral hemisphere of rat brains after 7 and 10 days, which was blocked by co-injection of excess amounts of TROA (10 mg/kg). The increased [(11)C]TROA binding on the ipsilateral side returned to basal levels within 14 days. In addition, quantitative real-time PCR revealed that increased expression of 20-HETE synthase was only shown on the ipsilateral side on day 7. These results indicate that [(11)C]TROA might be a useful PET probe for imaging of 20-HETE synthase in patients with cerebral ischemia.

Fenofibrate reduces mortality and precludes neurological deficits in survivors in murine model of Japanese encephalitis viral infection

BACKGROUND

Japanese encephalitis (JE), the most common form of viral encephalitis occurs periodically in endemic areas leading to high mortality and neurological deficits in survivors. It is caused by a flavivirus, Japanese encephalitis virus (JEV), which is transmitted to humans through mosquitoes. No effective cure exists for reducing mortality and morbidity caused by JEV infection, which is primarily due to excessive inflammatory response. Fenofibrate, a peroxisome proliferator-activated receptor-α (PPARα) agonist is known to resolve inflammation by repressing nuclear factor-κB (NF-κB) and enhancing transcription of anti-oxidant and anti-inflammatory genes. In addition, fenofibrate also up-regulates a class of proteins, cytochrome P4504Fs (Cyp4fs), which are involved in detoxification of the potent pro-inflammatory eicosanoid, leukotriene B(4) (LTB(4)) to 20-hydroxy LTB(4).

METHODOLOGY/PRINCIPAL FINDINGS

The neuroprotective effect of fenofibrate was examined using in vitro (BV-2 microglial cell line) and in vivo (BALB/c mice) models of JEV infection. Mice were treated with fenofibrate for 2 or 4 days prior to JEV exposure. Pretreatment with fenofibrate for 4 but not 2 days reduced mortality by 80% and brain LTB(4) levels decreased concomitantly with the induction of Cyp4f15 and 4f18, which catalyze detoxification of LTB(4) through hydroxylation. Expression of cytokines and chemokine decreased significantly as did microglial activation and replication of the JEV virus.

CONCLUSIONS/SIGNIFICANCE

Fenofibrate confers neuroprotection against Japanese encephalitis, in vivo, in mouse model of JEV infection. Thus, fenofibrate, a PPARα agonist that is commonly used as a hypolipidemic drug could potentially be used for prophylaxis during JE epidemics to reduce mortality and morbidity.