Platelet-activating Factor Acetylhydrolase Research Articles

Differential Proteomics of Cardiovascular Risk and Coronary Artery Disease in Humans.

BackgroundProteomics of atypical phenotypes may help unravel cardiovascular disease mechanisms.AimWe aimed to prospectively screen the proteome of four types of individuals: with or without coronary artery disease (CAD), each with or without multiple risk factors. Associations with individual risk factors and circulating biomarkers were also tested to provide a functional context to the protein hits.Materials and MethodsThe CAPIRE study (ClinicalTrials.gov Identifier: NCT02157662) is a cross-sectional study aimed at identifying possible new mechanisms promoting or protecting against atherothrombosis. Quantification (by aptamer technology), ranking (using partial least squares), and correlations (by multivariate regression) of ~5000 plasma proteins were performed in consecutive individuals aged 45–75 years, without previous cardiovascular disease, undergoing computed tomography angiography for suspected CAD, showing either >5/16 atherosclerotic segments (CAD+) or completely clean arteries (CAD−) and either ≤ 1 risk factor (RF+) or ≥3 risk factors (RF−) (based on history, blood pressure, glycemia, lipids, and smoking).ResultsOf 544 individuals, 39% were atypical (93 CAD+/RF−; 120 CAD−/RF+) and 61% typical (102 CAD+/RF+; 229 CAD−/RF−). In the comparison with CAD+/RF− adjusted for sex and age, CAD−/RF+ was associated with increased atrial myosin regulatory light chain 2 (MYO) and C-C motif chemokine-22 (C-C-22), and reduced protein shisa-3 homolog (PS-3) and platelet-activating factor acetylhydrolase (PAF-AH). Extending the analysis to the entire cohort, an additional 8 proteins were independently associated with CAD or RF; by logistic regression, the 12-protein panel alone discriminated the four groups with AUCROC's of 0.72–0.81 (overall p = 1.0e−38). Among them, insulin-like growth factor binding protein-3 is positively associated with RF, lower BMI, and HDL-cholesterol, renin with CAD higher glycated hemoglobin HbA1c, and smoking.ConclusionsIn a CCTA-based cohort, four proteins, involved in opposing vascular processes (healing vs. adverse remodeling), are specifically associated with low CAD burden in high CV-risk individuals (high MYO and C-C-22) and high CAD burden in low-risk subjects (high PS-3 and PAF-AH), in interaction with BMI, smoking, diabetes, HDL-cholesterol, and HbA1c. These findings could contribute to a deeper understanding of the atherosclerotic process beyond traditional risk profile assessment and potentially constitute new treatment targets.

Comprehensive Analysis of the Prognostic and Immunological Role of PAFAH1B in Pan-Cancer.

Platelet-activating factor acetylhydrolase 1B3 (PAFAH1B3) plays a critical role in cancer initiation, metastasis, and progression; however, it remains unknown how PAFAH1B3 impacts cancer diagnosis and prognosis or regulates the immune response to different types of cancer. In this study, PAFAH1B3 was elevated in human pan-cancer, and this correlated with greater pathology and poor prognosis, in particular for non-small cell lung cancer (NSCLC) and liver hepatocellular carcinoma (LIHC). In addition, PAFAH1B3 expression was positively associated with tumor mutational burden (TMB), microsatellite instability (MSI), immune cell infiltration, immune-modulatory related gene expression, and diverse cancer drug sensitivity in human cancer. Increased PAFAH1B3 expression correlated with poor overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) of NSCLC and LIHC, and has potential as an independent risk factor for overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) during LIHC. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis confirmed that PAFAH1B3 is primarily involved in immune regulation. More importantly, results demonstrated that PAFAH1B3 was upregulated in liver cancer cells lines and that knockdown of this gene significantly inhibited cell proliferation, migration, and invasion in liver hepatocellular carcinoma (LIHC). In summary, this study elucidates the clinical significance and biological function of PAFAH1B3 during liver hepatocellular carcinoma (LIHC) and may serve as a potential biomarker for the diagnosis and prognosis of various cancer types.

Iron chelation therapy with deferiprone improves oxidative status and red blood cell quality and reduces redox-active iron in β-thalassemia/hemoglobin E patients.

The oxidative status of twenty-three β-thalassemia/hemoglobin E patients was evaluated after administration of 75mg/kg deferiprone (GPO-L-ONE®) divided into 3 doses daily for 12 months. Serum ferritin was significantly decreased; the median value at the initial and final assessments was 2842 and 1719ng/mL, respectively. Progressive improvement with significant changes in antioxidant enzyme activity, including plasma paraoxonase (PON) and platelet-activating factor acetylhydrolase (PAF-AH), and in antioxidant enzymes in red blood cells (glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD)) were observed at 3-6months of treatment. The levels of total GSH in red blood cells were significantly increased at the end of the study. Improved red blood cell membrane integrity was also demonstrated using the EPR spin labeling technique. Membrane fluidity at the surface and hydrophobic regions of the red blood cell membrane was significantly changed after 12 months of treatment. In addition, a significant increase in hemoglobin content was observed (6.6±0.7 and 7.5±1.3g/dL at the initial assessment and at 6 months, respectively). Correlations were observed between hemoglobin content, membrane fluidity and antioxidant enzymes in red blood cells. The antioxidant activity of deferiprone may partly be explained by progressive reduction of redox active iron that catalyzes free radical reactions, as demonstrated by the EPR spin trapping technique. In conclusion, iron chelation therapy with deferiprone notably improved the oxidative status in thalassemia, consequently reducing the risk of oxidative-related complications. Furthermore, the improvement in red blood cell quality may improve the anemia situation in patients.

Platelet-activating factor acetyl hydrolase IB2 dysregulated cell proliferation in ovarian cancer

BackgroundOvarian cancer is the leading cause of death from gynaecologic illnessed worldwide. Platelet-activating factor acetyl hydrolase IB2 (PAF-AH IB2) is an intracellular serine esterase that hydrolyzes platelet-activating factor, a G-protein-like trimer with two catalytic subunits and one regulatory subunit. The regulatory role of PAF-AH IB2 in the oncogenesis of ovarian cancer is not well understood.MethodsIn this study, the TCGA dataset and clinical cancer tissue microarray were utilized to investigate abnormal overexpression of PAF-AH IB2 in ovarian cancer. To investigate the impact on the cell proliferation, migration, and tumorigenicity in vitro, PAF-AH IB2 stable knocking down (KD) ovarian cancer cells were established by ShRNA. The whole transcription profiling, tyrosine kinase profiling and standard cell functional assays were integrated to explore the biological importance and mechanism of PAF-AH IB2 modulated in ovarian cancer.ResultsPAF-AH IB2 was identified significantly overexpression in four subtypes of ovarian cancer. In vitro, PAF-AH IB2 KD significantly inhibited cancer cell proliferation, migration, and tumorigenicity, activated caspases and caused cell cycle arrest, and made the cells more sensitive to PAF. PAF-AH 1B2 KD cells down-regulated several key regulators of the multiple tyrosine kinases-mediated signaling pathway, suggesting a novel interaction network between the growth factor receptors pathway and PAF-AH 1B2 mediated PAF signalling.ConclusionsThese findings revealed a previously undiscovered role for PAF-AH IB2 as a potenial therapy target and essential signaling mediators in ovarian cancer pathogenesis, as well as new possible preventive and therapeutic strategies to inhibit this enzyme in clinical treatment for ovarian cancer.

Metabolomic profiling revealed altered lipid metabolite levels in childhood food allergy

The pathophysiology of childhood food allergy (FA) and its natural history are poorly understood. Clarification of the underlying mechanism may help identify novel biomarkers and strategies for clinical intervention in children with FA. This study aimed to identify metabolites associated with the development and resolution of FA. The metabolomic profiles of 20 children with FA and 20 healthy controls were assessed by liquid chromatography-tandem mass spectrometry. Comparative analysis was performed to identify metabolites associated with FA and FA resolution. For subjects with FA, serum samples were collected at the time of diagnosis and after resolution to identify the changes in metabolite levels. The selected metabolites were then quantified in a quantification cohort to validate the results. Finally, genome-wide association analysis of the metabolite levels was performed. The study demonstrated a significantly higher level of sphingolipid metabolites and a lower level of acylcarnitine metabolites in children with FA than those in healthy controls. At diagnosis, subjects with resolving FA had a significantly high level of omega-3 metabolites and a low level of platelet-activating factors compared to persistent FA. However, the level of omega-3 metabolites decreased in children with resolving FA but increased in children with persistent FA during the same time. The quantification data of omega-3-derived resolvins, platelet-activating factor, and platelet-activating factor acetylhydrolase activity further supported these results. The lipid metabolite profile is closely related to childhood FA and FA resolution. This study suggests potential predictive biomarkers and provides insight into the mechanisms underlying childhood FA.

Association of PAF and its Metabolic Enzymes with GGT and the Fatty Liver Index in Healthy Volunteers.

Platelet-activating-factor (PAF) is a lipid inflammatory mediator implicated in liver disease. Its main biosynthetic enzymes are cytidine diphosphate (CDP)-choline: 1-alkyl-2-acetyl-sn-glycerol-cholinephosphotransferase (PAF-CPT) and acetyl-coenzyme A: lyso-PAF-acetyltransferases (Lyso-PAF-AT). At the same time, PAF acetylhydrolase (PAF-AH) and lipoprotein-associated phospholipase A2 (Lp-PLA2 ) degrade PAF. To explore the relation of PAF metabolism with liver diseases and non-alcoholic fatty liver disease, as reflected by the fatty liver index (FLI). In 106 healthy volunteers, PAF concentration, the activity of its metabolic enzymes and gamma-glutamyl transferase (GGT) were measured in whole blood, leukocytes and serum, respectively and the FLI was calculated. Partial correlations and linear regression models were used. In males, serum GGT activity was positively correlated with abdominal fat (as assessed by analysis of a manually defined region of interest in dual-energy X-ray absorptiometry), triacylglycerols, bound-PAF and Lp-PLA2 , while the FLI was positively correlated with Lp-PLA2 activity. In females, serum GGT activity was negatively associated with high-density lipoprotein cholesterol (HDL-C) (age adjusted correlations, all p<0.05). Lp-PLA2 was a significant determinant of serum GGT activity in males after controlling for age, low- density lipoprotein cholesterol (LDL-C) and abdominal fat. The addition of bound-PAF in the model significantly increased the explained variance of serum GGT activity (total variance explanation 30%). Bound-PAF and Lp-PLA2 activity predicted serum GGT activity while Lp-PLA2 was also related to FLI. Our findings shed light on the metabolic pathways linking Lp-PLA2 to other atherosclerosis and/or oxidative markers, such as HDL-C, LDL-C, GGT and FLI and underline the important role of PAF.

Lysophosphatidylcholine 16:0, a Promising Biomarker for Severe Fibromyalgia

Fibromyalgia (FM) is a complex disease without any clear physiopathology, thus treating FM remains challenging for physicians. In this article Hung et al. propose a new mouse model of FM in which adult mice are exposed to repeated and intermittent sound stress (RISS). These stressors are shown to have an effect at the cellular level: leucocytes generate a high amount of reactive oxygen species (ROS), which triggers plasma lipid peroxidation and an excessive production of lysophosphatidylcholine (LPC) 16:0. LPC16:0 molecules then activate acid-sensing ion channel 3 (ASIC3) on muscle nociceptors, generating a central sensitization process responsible for the development of FM-like phenotypes (hyperalgesia, chronic fatigue, and anxiety). In the second part, a clinical investigation was performed on patients suffering from mild and severe FM. During the month preceding the study, FM patients perceived more daily stressors than healthy controls (HC). In severe FM patients, LPC16:0 levels are correlated with ongoing pain severity. This study suggests that LPC16:0 could be a biomarker for FM, particularly in its severe forms, and proposes to further investigate the effects of platelet-activating factor acetylhydrolase (PAF-AH) inhibitors such as darapladib on fibromyalgia. These molecules could prove to be interesting therapeutic compounds for the treatment of severe FM.

Clinical significance of plasma PAF acetylhydrolase activity measurements as a biomarker of anaphylaxis: Cross-sectional study.

IntroductionPlatelet-activating factor (PAF) has a direct role as a mediator in the pathogenesis of various disorders with an inflammatory component, including those with allergic aetiology. The peripheral blood concentration of PAF is dynamically regulated by plasma PAF acetylhydrolase (PAF-AH). Previous research suggest that low activity of plasma PAF-AH could be a predictive marker for increased severity of some types of allergic hypersensitivity reactions–especially anaphylaxis. The purpose of the study was to evaluate the association between plasma PAF-AH activity and severity in patients with anaphylactic reactions following a wasp or bee sting.Materials and methodsThe study group of 89 patients was divided into two subgroups depending on the increasing severity of the most severe anaphylactic reaction in the past, which was assessed according to the Müller’s scale. The first subgroup included participants with a history of hypersensitivity reactions up to grade II. The second subgroup consisted of patients who have experienced at least one grade III or IV reactions in the past. A control group of 20 people was established. Plasma PAF-AH activity was measured using a colorimetric method.ResultsIt has been observed that plasma activity of platelet-activating factor acetylhydrolase was significantly lower in patients with anaphylaxis history compared to the control group with negative atopic history (on average 21.38 nmol/min/ml for the control group, 9.47 nmol/min/ml for the first subgroup and 10.16 nmol/min/ml for the second subgroup, in both cases p < 0.0001).ConclusionThe plasma activity of PAF-AH is a promising parameter that can help to distinguish a group of patients not threatened with development of anaphylaxis and not requiring laborious or expensive prophylactic procedures.

Deficiency of Type I Platelet-Activating Factor-Acetylhydrolase Catalytic Subunits Causes an Increase in Body Weight.

Type I platelet-activating factor-acetylhydrolase (PAF-AH) forms a complex consisting of two catalytic subunits (α1 and/or α2) with a regulatory subunit (β). Although this protein was discovered as an enzyme that degrades an acetyl ester linked at the sn-2 position of platelet-activating factor (PAF), its physiological function remains unknown. In this study, to examine whether knockout mice lacking the catalytic subunits of this enzyme showed a different phenotype from that of wild-type mice, we measured and compared the body weights of knockout mice and control mice. The body weights of knockout mice were significantly increased compared to those of the control mice during 6 to 20 weeks from birth. Food intake was also significantly increased in knockout mice compared with control mice during these periods. Since a decrease in testis weight was reported in the knockout mice, we expected a decrease in testosterone levels. We measured and compared the amounts of testosterone in the serum and testis of knockout and control mice using liquid chromatography-tandem mass spectrometry, and found that testosterone levels in both the serum and testis were significantly decreased in the knockout mice compared with the control mice. These results suggest that a deficiency of type I PAF-AH catalytic subunits causes an increase in body weight, in part, due to reduced testosterone levels in male mice.

A novel missense variant in the EML1 gene associated with bilateral ribbon-like subcortical heterotopia leads to ciliary defects

Heterotopia is a brain malformation caused by a failed migration of cortical neurons during development. Clinical symptoms of heterotopia vary in severity of intellectual disability and may be associated with epileptic disorders. Abnormal neuronal migration is known to be associated with mutations in the doublecortin gene (DCX), the platelet-activating factor acetylhydrolase gene (PAFAH1B1), or tubulin alpha-1A gene (TUBA1A). Recently, a new gene encoding echinoderm microtubule-associated protein-like 1 (EML1) was reported to cause a particular form of subcortical heterotopia, the ribbon-like subcortical heterotopia (RSH). EML1 mutations are inherited in an autosomal recessive manner. Only six unrelated EML1-associated heterotopia-affected families were reported so far. The EML1 protein is a member of the microtubule-associated proteins family, playing an important role in microtubule assembly and stabilization as well as in mitotic spindle formation in interphase. Herein, we present a novel homozygous missense variant in EML1 (NM_004434.2: c.692G>A, NP_004425.2: p.Gly231Asp) identified in a male RSH-affected patient. Our clinical and molecular findings confirm the genotype-phenotype associations of EML1 mutations and RSH. Analyses of patient-derived fibroblasts showed the significantly reduced length of primary cilia. In addition, our results presented, that the mutated EML1 protein did not change binding capacities with tubulin. The data described herein will expand the mutation spectrum of the EML1 gene and provide further insight into molecular and cellular bases of the pathogenic mechanisms underlying RSH.

Platelet-Activating Factor Acetylhydrolase Expression in BRCA1 Mutant Ovarian Cancer as a Protective Factor and Potential Negative Regulator of the Wnt Signaling Pathway.

Aberrantly activated Wnt/β-catenin signaling pathway, as well as platelet-activating factor (PAF), contribute to cancer progression and metastasis of many cancer entities. Nonetheless, the role of the degradation enzyme named platelet-activating factor acetylhydrolase (PLA2G7/PAF-AH) in ovarian cancer etiology is still unclear. This study investigated the functional impact of platelet-activating factor acetylhydrolase on BRCA1 mutant ovarian cancer biology and its crosstalk with the Wnt signaling pathway. PAF-AH, pGSK3β, and β-catenin expressions were analyzed in 156 ovarian cancer specimens by immunohistochemistry. PAF-AH expression was investigated in ovarian cancer tissue, serum of BRCA1-mutated patients, and in vitro in four ovarian cancer cell lines. Functional assays were performed after PLA2G7 silencing. The association of PAF-AH and β-catenin was examined by immunocytochemistry. In an established ovarian carcinoma collective, we identified PAF-AH as an independent positive prognostic factor for overall survival (median 59.9 vs. 27.4 months; p = 0.016). PAF-AH correlated strongly with the Wnt signaling proteins pGSK3β (Y216; nuclear: cc = 0.494, p < 0.001; cytoplasmic: cc = 0.488, p < 0.001) and β-catenin (nuclear: cc = 0.267, p = 0.001; cytoplasmic: cc = 0.291, p < 0.001). In particular, high levels of PAF-AH were found in tumor tissue and in the serum of BRCA1 mutation carriers. By in vitro expression analysis, a relevant gene and protein expression of PLA2G7/PAF-AH was detected exclusively in the BRCA1-negative ovarian cancer cell line UWB1.289 (p < 0.05). Functional assays showed enhanced viability, proliferation, and motility of UWB1.289 cells when PLA2G7/PAF-AH was downregulated, which underlines its protective character. Interestingly, by siRNA knockdown of PLA2G7/PAF-AH, the immunocytochemistry staining pattern of β-catenin changed from a predominantly membranous expression to a nuclear one, suggesting a negative regulatory role of PAF-AH on the Wnt/β-catenin pathway. Our data provide evidence that PAF-AH is a positive prognostic factor with functional impact, which seems particularly relevant in BRCA1 mutant ovarian cancer. For the first time, we show that its protective character may be mediated by a negative regulation of the Wnt/β-catenin pathway. Further studies need to specify this effect. Potential use of PAF-AH as a biomarker for predicting the disease risk of BRCA1 mutation carriers and for the prognosis of patients with BRCA1-negative ovarian cancer should be explored.

Aberrant Expression of PAFAH1B3 Affects Proliferation and Apoptosis in Osteosarcoma.

Osteosarcoma is a major malignant tumor of bone and soft tissue, which is presenting with early metastasis and a high mortality rate. Platelet activating factor acetylhydrolase 1B3 (PAFAH1B3), a cancer-relevant molecular, was found to play a vital role in tumorigenesis and aggressiveness in several cancer types. However, the roles and the regulating mechanisms of PAFAH1B3 in osteosarcoma progression remain unclear. PAFAH1B3 expression was detected by immunohistochemistry in 83 osteosarcoma tissues and 44 paired adjacent normal bone tissues. In vitro, loss-of-function assay was performed to explore the role of PAFAH1B3 in osteosarcoma cells. Tumor xenograft growth assay was used to verify the effect of PAFAH1B3 knockdown on osteosarcoma growth in vivo. Chip assay was carried out to investigate the mechanism in osteosarcoma proliferation regulated by PAFAH1B3. PAFAH1B3 was overexpressed in osteosarcoma tissues and cell lines. Moreover, PAFAH1B3 knockdown inhibited osteosarcoma cell proliferation and promoted apoptosis in vitro, and also suppressed osteosarcoma growth in vivo. Furthermore, the proliferative effect of PAFAH1B3 in osteosarcoma was related to the regulation of the expression of EIF4EBP1, MYC, PTGS2 and RPS6KB1. This study demonstrated the biological function of PAFAH1B3 on osteosarcoma proliferation. This research suggested that PAFAH1B3 could be a novel therapeutic target for osteosarcoma patients.

Consumption of Enriched Yogurt with PAF Inhibitors from Olive Pomace Affects the Major Enzymes of PAF Metabolism: A Randomized, Double Blind, Three Arm Trial

Platelet-activating factor (PAF), a proinflammatory lipid mediator, plays a crucial role in the formation of the atherosclerotic plaque. Therefore, the inhibition of endothelium inflammation by nutraceuticals, such as PAF inhibitors, is a promising alternative for preventing cardiovascular diseases. The aim of the present study was to evaluate the impact of a new functional yogurt enriched with PAF inhibitors of natural origin from olive oil by-products on PAF metabolism. Ninety-two apparently healthy, but mainly overweight volunteers (35–65 years) were randomly allocated into three groups by block-randomization. The activities of PAF’s biosynthetic and catabolic enzymes were measured, specifically two isoforms of acetyl-CoA:lyso-PAF acetyltransferase (LPCATs), cytidine 5′-diphospho-choline:1-alkyl-2-acetyl-sn-glycerol cholinephosphotransferase (PAF-CPT) and two isoforms of platelet activating factor acetylhydrolase in leucocytes (PAF-AH) and plasma (lipoprotein associated phospholipase-A2, LpPLA2). The intake of the enriched yogurt resulted in reduced PAF-CPT and LpPLA2 activities. No difference was observed in the activities of the two isoforms of lyso PAF-AT. In conclusion, intake of yogurt enriched in PAF inhibitors could favorably modulate PAF biosynthetic and catabolic pathways.

An autoantigen profile of human A549 lung cells reveals viral and host etiologic molecular attributes of autoimmunity in COVID-19

We aim to establish a comprehensive COVID-19 autoantigen atlas in order to understand autoimmune diseases caused by SARS-CoV-2 infection. Based on the unique affinity between dermatan sulfate and autoantigens, we identified 348 proteins from human lung A549 cells, of which 198 are known targets of autoantibodies. Comparison with current COVID data identified 291 proteins that are altered at protein or transcript level in SARS-CoV-2 infection, with 191 being known autoantigens. These known and putative autoantigens are significantly associated with viral replication and trafficking processes, including gene expression, ribonucleoprotein biogenesis, mRNA metabolism, translation, vesicle and vesicle-mediated transport, and apoptosis. They are also associated with cytoskeleton, platelet degranulation, IL-12 signaling, and smooth muscle contraction. Host proteins that interact with and that are perturbed by viral proteins are a major source of autoantigens. Orf3 induces the largest number of protein alterations, Orf9 affects the mitochondrial ribosome, and they and E, M, N, and Nsp proteins affect protein localization to membrane, immune responses, and apoptosis. Phosphorylation and ubiquitination alterations by viral infection define major molecular changes in autoantigen origination. This study provides a large list of autoantigens as well as new targets for future investigation, e.g., UBA1, UCHL1, USP7, CDK11A, PRKDC, PLD3, PSAT1, RAB1A, SLC2A1, platelet activating factor acetylhydrolase, and mitochondrial ribosomal proteins. This study illustrates how viral infection can modify host cellular proteins extensively, yield diverse autoantigens, and trigger a myriad of autoimmune sequelae. Our work provides a rich resource for studies into “long COVID” and related autoimmune sequelae.

MicroRNA-212-5p and its target PAFAH1B2 suppress vascular proliferation and contraction via the downregulation of RhoA.

Vascular remodeling and contraction contribute to the development of hypertension. We investigated the role of miR-212-5p and its downstream target in vascular smooth muscle cell (VSMC) proliferation, migration, and contraction. MicroRNA microarray and PCR analyses showed that miR-212-5p expression was increased with angiotensin II treatment in vivo and in vitro. Moreover, miR-212-5p mimic treatment attenuated and miR-212-5p inhibitor treatment increased VSMC proliferation and migration. Additionally, miR-212-5p mimic treatment suppressed VSMC contraction and related gene expression [Ras homolog gene family member A (RhoA) and Rho-associated protein kinase 2], while miR-212-5p inhibitor treatment exerted opposite effects. Bioinformatics analysis revealed that platelet-activating factor acetylhydrolase 1B2 (PAFAH1B2) is a target of miR-212-5p. miR-212-5p mimic treatment significantly reduced and miR-212-5p inhibitor treatment increased PAFAH1B2 expression. Furthermore, PAFAH1B2 expression was decreased in angiotensin II-treated aortic tissues and VSMCs. PAFAH1B2 was ubiquitously expressed in most adult rat tissues. In the vasculature, PAFAH1B2 was only distributed in the cytoplasm. PAFAH1B2 overexpression decreased A10 cell proliferation, while PAFAH1B2 knockdown increased A10 cell proliferation and cyclin D1 mRNA levels. PAFAH1B2 knockdown stimulated VSMC contraction and RhoA expression. These results suggest that miR-212-5p and PAFAH1B2 are novel negative regulators of VSMC proliferation, migration, and contraction in hypertension.

Kupffer cell release of platelet activating factor drives dose limiting toxicities of nucleic acid nanocarriers

This work establishes that Kupffer cell release of platelet activating factor (PAF), a lipidic molecule with pro-inflammatory and vasoactive signaling properties, dictates dose-limiting siRNA nanocarrier-associated toxicities. High-dose intravenous injection of siRNA-polymer nano-polyplexes (si-NPs) elicited acute, shock-like symptoms in mice, associated with increased plasma PAF and consequently reduced PAF acetylhydrolase (PAF-AH) activity. These symptoms were completely prevented by prophylactic PAF receptor inhibition or Kupffer cell depletion. Assessment of varied si-NP chemistries confirmed that toxicity level correlated to relative uptake of the carrier by liver Kupffer cells and that this toxicity mechanism is dependent on carrier endosome disruptive function. 4T1 tumor-bearing mice, which exhibit increased circulating leukocytes, displayed greater sensitivity to these toxicities. PAF-mediated toxicities were generalizable to commercial delivery reagent in vivo-jetPEI® and an MC3 lipid formulation matched to an FDA-approved nanomedicine. These collective results establish Kupffer cell release of PAF as a key mediator of siRNA nanocarrier toxicity and identify PAFR inhibition as an effective strategy to increase siRNA nanocarrier tolerated dose.

LPCAT1 enhances castration resistant prostate cancer progression via increased mRNA synthesis and PAF production.

Our previously study shown that Lysophosphatidylcholine Acyltransferase1 (LPCAT1) is overexpressed in castration resistant prostate cancer (CRPC) relative to primary prostate cancer (PCa), and androgen controls its expression via the Wnt signaling pathway. While highly expressed in CRPC, the role of LPCAT1 remains unclear. In vitro cell experiments referred to cell transfection, mutagenesis, proliferation, migration, invasion, cell cycle progression and apoptosis, Western blotting, Pulse-chase RNA labeling. BALB/c nude mice were used for in vivo experiments. We found that LPCAT1 overexpression enhanced the proliferation, migration, and invasion of CRPC cells both in vitro and in vivo. Silencing of LPCAT1 reduced the proliferation and the invasive capabilities of CRPC cells. Providing exogenous PAF to LPCAT1 knockdown cells increased their invasive capabilities; however platelet activating factor acetylhydrolase (PAF-AH) and the PAFR antagonist ABT-491 both reversed this phenotype; proliferation of CRPC cells was not affected in either model. LPCAT1 was found to mediate CRPC growth via nuclear re-localization and Histone H4 palmitoylation in an androgen-dependent fashion, increasing mRNA synthesis rates. We also found that LPCAT1 overexpression led to CRPC cell resistance to treatment with paclitaxel. LPCAT1 overexpression in CRPC cells drives tumor progression via increased mRNA synthesis and PAF production. Our results highlight LPCAT1 as a viable therapeutic target in the context of CRPC.

Silencing linc00662 inhibits cell proliferation and colony formation of lung cancer cells via regulating the miR-145-5p-PAFAH1B2 axis.

Lung cancer is the most common cause of cancer-related death in the world. Long non-coding RNAs (lncRNAs) are longer than 200 nucleotide transcripts, and are not translated into protein. The lncRNA linc00662 is overexpressed in lung cancer; however, its role in lung cancer is still unknown. In our study, by analyzing the TCGA data, we found that linc00662 was overexpressed in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). We knocked-down the expression of linc00662 using siRNA, and found that silencing linc00662 significantly inhibited the proliferation and colony formation of the lung cancer cell lines A549 and H460. We also found that knockdown of linc00662 increased the expression of the microRNA miR-145-5p and decreased the expression of the platelet-activating factor acetylhydrolase IB subunit beta (PAFAH1B2) gene. We further show that linc00662 binds with miR-145-5p, and that miR-145-5p binds to the 3'UTR of PAFAH1B2. miR-145-5p negatively regulates PAFAH1B2 both at the mRNA and the protein level. Loss of miR-145-5p abolished the inhibitory effects of silencing linc00662 on the proliferation and colony formation of A549 and H460 cells. These findings indicate that linc00662 functions as an oncogene by acting as a competing endogenous RNA (ceRNA) and sponges and regulates miR-145-5p in lung cancer, and thus may provide a potential target for treating lung cancer.

Evaluation of maternal plasma platelet activating factor acetylhydrolase activity and mRNA expression in pre-eclampsia: a case control study

Preeclampsia (PE) remains a leading cause of maternal morbidity and mortality all over the world. However, its aetiology and pathophysiology remain elusive. Platelet activating factor (PAF) is produced in response to oxidative stress and is a potent hypotensive agent. PAF acetylhydrolase (PAF-AH) inactivates PAF and is seen to decrease in normotensive women. The role of PAF-AH in preeclampsia has been in investigational literature, so far. The few studies done have shown a positive association of elevated levels of PAF-AH with preeclampsia. However, this marker has not been studied in the Indian population to-date and such studies are needed to elucidate the pathogenesis of this condition. Our study aimed to determine the PAF-AH activity by spectrophotometric assay in maternal plasma of 73 PE patients versus 73 normotensive controls and plasma PAF-AH mRNA expression to know the aberration of PAF-AH activity at the genetic level. Relative mRNA expression was calculated by Δ DCT method and a fold change was calculated by 2–ΔDCT. We found that the mean plasma PAF-AH activity levels among cases was significantly higher than the normotensive controls. However, the mRNA expression of the PAF-AH gene was similar between the cases and controls, as well as between severe and non-severe preeclampsia (true fold change =1). To conclude, PAF-AH appears to be increased in women with preeclampsia and hence may contribute to pathophysiology and severity. However, a larger sample size will be required to reiterate this association. Recently, PAF-AH inhibitors such as Darapladib has been tested as a therapeutic option in atherosclerosis. After studying the role of PAF-AH in the pathogenesis of PE, PAF-AH inhibitors may be used as a therapeutic tool in the future in PE. IMPACT STATEMENT What is already known on this subject? Platelet activating factor (PAF) is produced in response to oxidative stress and is a potent hypotensive agent. PAF acetylhydrolase (PAF-AH) hydrolyses and inactivates PAF and is seen to decrease in normotensive women. The role of platelet activating factor-acetylhydrolase (PAF-AH) in preeclampsia has been investigational so far. Few studies done have shown a positive association of elevated levels of PAF-AH in preeclamptic women. What do the results of this study add? Our study aimed to determine the activity of PAF-AH in maternal plasma of PE patients versus normal pregnancy and plasma PAF-AH mRNA expression to know the aberration of PAF-AH activity at the level of the gene. We found that plasma PAF-AH activity among preeclamptics was significantly higher than in the controls with a possible role in early-onset preeclampsia (<32 weeks), in the Indian population. This marker has never been studied in this population earlier. The results of our study re-emphasised its role in the pathogenesis of preeclampsia. What are the implications of these findings for clinical practice and/or further research? Such studies are important to not only give us a greater understanding of the various pathways involved in this multifactorial dreaded condition, but can also offer us a marker for early identification of women at risk. Recently, PAF-AH inhibitors like Darapladib has been tested as a therapeutic option in atherosclerosis. After studying the role of PAF-AH in the pathogenesis of PE, PAF-AH inhibitors may be used as a therapeutic tool in the future in PE.

Phospholipase A2 superfamily in cancer.

Phospholipase A2 enzymes (PLA2s) comprise a superfamily that is generally divided into six subfamilies known as cytosolic PLA2s (cPLA2s), calcium-independent PLA2s (iPLA2s), secreted PLA2s (sPLA2s), lysosomal PLA2s, platelet-activating factor (PAF) acetylhydrolases, and adipose specific PLA2s. Each subfamily consists of several isozymes that possess PLA2 activity. The first three PLA2 subfamilies play important roles in inflammation-related diseases and cancer. In this review, the roles of well-studied enzymes sPLA2-IIA, cPLA2α and iPLA2β in carcinogenesis and cancer development were discussed. sPLA2-IIA seems to play conflicting roles and can act as a tumor suppressor or a tumor promoter according to the cancer type, but cPLA2α and iPLA2β play protumorigenic role in most cancers. The mechanisms of PLA2-mediated signal transduction and crosstalk between cancer cells and endothelial cells in the tumor microenvironment are described. Moreover, the mechanisms by which PLA2s mediate lipid reprogramming and glycerophospholipid remodeling in cancer cells are illustrated. PLA2s as the upstream regulators of the arachidonic acid cascade are generally high expressed and activated in various cancers. Therefore, they can be considered as potential pharmacological targets and biomarkers in cancer. The detailed information summarized in this review may aid in understanding the roles of PLA2s in cancer, and provide new clues for the development of novel agents and strategies for tumor prevention and treatment.