Secreted phospholipase A2 revisited

Comprehensive insights of etiological drivers of hepatocellular carcinoma: Fostering targeted nano delivery to anti-cancer regimes

Hepatocellular carcinoma (HCC) stands as one of the most prevalent and deadliest malignancies on a global scale. Its complex pathogenesis arises from multifactorial etiologies, including viral infections, metabolic syndromes, and environmental carcinogens, all of which drive genetic and molecular aberrations in hepatocytes. This intricate condition is associated with multiple causative factors, resulting in the abnormal activation of various cellular and molecular pathways. Given that HCC frequently manifests within the context of a compromised or cirrhotic liver, coupled with the tendency of late-stage diagnoses, the overall prognosis tends to be unfavorable. Systemic therapy, especially conventional cytotoxic drugs, generally proves ineffective. Despite advancements in therapeutic interventions, conventional treatments such as chemotherapy often exhibit limited efficacy and substantial systemic toxicity. In this context, nanomedicine, particularly lipid-based nanoparticles (LNPs), has emerged as a promising strategy for enhancing drug delivery specificity and reducing adverse effects. This review provides a comprehensive overview of the molecular and metabolic underpinnings of HCC. Furthermore, we explored the role of lipid-based nano-formulations including liposomes, solid lipid nanoparticles, and nanostructured lipid carriers in targeted drug delivery for HCC. We have highlighted recent advances in LNP-based delivery approaches, FDA-approved drugs, and surface modification strategies to improve liver-specific delivery and therapeutic efficacy. It will provide a comprehensive summary of various treatment strategies, recent clinical advances, receptor-targeting strategies and the role of lipid composition in cellular uptake. The review concludes with a critical assessment of existing challenges and future prospects in nanomedicines-driven HCC therapy.

WITHDRAWN: Progranulin inhibits phospholipase sPLA2-IIA to control neuroinflammation

The authors have withdrawn this manuscript because more work is needed to fully define the role of sPLA2-IIA. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

Transcriptomic Profiling Reveals Altered Expression of Genes Involved in Metabolic and Immune Processes in NDV-Infected Chicken Embryos

OBJECTIVE

The poultry industry is significantly impacted by viral infections, particularly Newcastle Disease Virus (NDV), which leads to substantial economic losses. It is essential to comprehend how the sequence of development affects biological pathways and how early exposure to infections might affect immune responses.

METHODS

This study employed transcriptome analysis to investigate host-pathogen interactions by analyzing gene expression changes in NDV-infected chicken embryos' lungs.

RESULT

RNA-Seq reads were aligned with the chicken reference genome (Galgal7), revealing 594 differentially expressed genes: 264 upregulated and 330 downregulated. The most overexpressed genes, with logFC between 8.15 and 8.75, included C8A, FGG, PIT54, FETUB, APOC3, and FGA. Notably, downregulated genes included BPIFB3 (-4.46 logFC) and TRIM39.1 (-4.26 logFC). The analysis also identified 29 novel transcripts and 20 lncRNAs that were upregulated. Gene Ontology and KEGG pathways' analyses revealed significant alterations in gene expression related to immune function, metabolism, cell cycle, nucleic acid processes, and mitochondrial activity due to NDV infection. Key metabolic genes, such as ALDOB (3.27 logFC), PRPS2 (2.66 logFC), and XDH (2.15 logFC), exhibited altered expression patterns, while DCK2 (-1.99 logFC) and TK1 (-2.11 logFC) were also affected. Several immune-related genes showed significant upregulation in infected lung samples, including ALB (6.15 logFC), TLR4 (1.86 logFC), TLR2 (2.79 logFC), and interleukin receptors, such as IL1R2 (3.15 logFC) and IL22RA2 (1.37 logFC). Conversely, genes such as CXCR4 (-1.49 logFC), CXCL14 (-2.57 logFC), GATA3 (-1.51 logFC), and IL17REL (-2.93 logFC) were downregulated. The higher expression of HSP genes underscores their vital role in immune responses.

CONCLUSION

Comprehension of these genes' interactions is essential for regulating viral replication and immune responses during infections, potentially aiding in the identification of candidate genes for poultry breed improvement amidst NDV challenges.

Synthesis, molecular modelling, and biological evaluation of novel quinoxaline derivatives for treating type II diabetes

Quinoxalines are benzopyrazine derivatives with significant therapeutic impact in the pharmaceutical industry. They proved to be useful against inflammation, bacterial, fungal, viral infection, diabetes and other applications. Very recently, in January 2024, the FDA approved new quinoxaline containing drug, erdafitinib for treatment of certain carcinomas. Despite the diverse biological activities exhibited by quinoxaline derivatives and the role of secretory phospholipase A2 (sPLA2) in diabetes-related complications, the potential of sPLA2-targeting quinoxaline-based inhibitors to effectively address these complications remains unexplored. Therefore, we designed novel sPLA2- and α-glucosidase-targeting quinoxaline-based heterocyclic inhibitors to regulate elevated post-prandial blood glucose linked to patients with diabetes-related cardiovascular complications. Compounds 5a-d and 6a-d were synthesised by condensing quinoxaline hydrazides with various aryl sulphonyl chlorides. Biological screening revealed compound 6a as a potent sPLA2 inhibitor (IC50 = 0.0475 µM), whereas compound 6c most effectively inhibited α-glucosidase (IC50 = 0.0953 µM), outperforming the positive control acarbose. Moreover, compound 6a was the best inhibitor for both enzymes. Molecular docking revealed pharmacophoric features, highlighting the importance of a sulfonohydrazide moiety in the structural design of these compounds, leading to the development of potent sPLA2 and α-glucosidase inhibitors. Collectively, our findings helped identify promising candidates for developing novel therapeutic agents for treating diabetes mellitus.

Phospholipase A2 expression in prostate cancer as a biomarker of good prognosis: A comprehensive study in patients with long follow-up

BACKGROUND

Phospholipase A2 (PLA2) is a large family of enzymes involved in the inflammatory process that catalyzes the hydrolysis of membrane phospholipids, leading to the production of free fatty acids and lysophospholipids, starting the arachidonic acid cascade. Their expression has been related to the behavior of several cancers. Our objective is to search for PLA2 expression in prostate cancer (PCa) tissue that correlates with prognosis and survival.

METHODS

Using qRT-PCR, we analyzed the expression levels of PLA2G1B, PLA2G2A, PLA2G2D, PLA2G4A, PLA2G4B, PLA2G4C, PLA2G4D, PLA2G4E, PLA2G4F, PLA2G6, PLA2G7, PLA2G16, PNPLA1, and PNPLA2 in PCa tissue from 108 patients submitted to radical prostatectomy, followed by a mean time of 163 months.

RESULTS

All PLA2 was overexpressed in PCa compared to normal tissue. Interestingly, higher expression of some PLA2 was related to favorable prognostic factors: lower levels of PSA (PLA2G2A, PLA2G4D), lower rates of lymph node metastasis (PLA2G16 and PLA2G1B), and organ-confined disease (PLA2G4A). Most importantly, PLAG4B was independently related to longer disease-free survival.

CONCLUSION

This is the first study exploring comprehensively the expression levels of PLA2 in PCa, showing that the higher expression of some PLA2 should be used as biomarkers of good prognosis and longer disease-free survival.

The Abl1 tyrosine kinase is a key player in doxorubicin-induced cardiomyopathy and its p53/p73 cell death mediated signaling differs in atrial and ventricular cardiomyocytes

BACKGROUND

Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling.

RESULTS

Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis.

CONCLUSIONS

The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.

Biosynthesis and Metabolism of ApoB-Containing Lipoproteins

Recent advances in human genetics, together with a substantial body of epidemiological, preclinical and clinical trial evidence, strongly support a causal relationship between triglyceride-rich lipoproteins (TRLs) and atherosclerotic cardiovascular disease. Consequently, the secretion and metabolism of TRLs have a significant impact on cardiovascular health. This knowledge underscores the importance of understanding the molecular mechanisms and regulation of very-low-density lipoprotein (VLDL) and chylomicron biogenesis. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL, leading to many ground-breaking molecular insights. Furthermore, the identification of molecular control mechanisms related to triglyceride metabolism has greatly advanced our understanding of the complex metabolism of TRLs. In this review, we explore recent advances in the assembly, secretion, and metabolism of TRLs. We also discuss available treatment strategies for hypertriglyceridemia.

From Beats to Metabolism: the Heart at the Core of Interorgan Metabolic Cross Talk

The heart, once considered a mere blood pump, is now recognized as a multifunctional metabolic and endocrine organ. Its function is tightly regulated by various metabolic processes, at the same time it serves as an endocrine organ, secreting bioactive molecules that impact systemic metabolism. In recent years, research has shed light on the intricate interplay between the heart and other metabolic organs, such as adipose tissue, liver, and skeletal muscle. The metabolic flexibility of the heart and its ability to switch between different energy substrates play a crucial role in maintaining cardiac function and overall metabolic homeostasis. Gaining a comprehensive understanding of how metabolic disorders disrupt cardiac metabolism is crucial, as it plays a pivotal role in the development and progression of cardiac diseases. The emerging understanding of the heart as a metabolic and endocrine organ highlights its essential contribution to whole body metabolic regulation and offers new insights into the pathogenesis of metabolic diseases, such as obesity, diabetes, and cardiovascular disorders. In this review, we provide an in-depth exploration of the heart's metabolic and endocrine functions, emphasizing its role in systemic metabolism and the interplay between the heart and other metabolic organs. Furthermore, emerging evidence suggests a correlation between heart disease and other conditions such as aging and cancer, indicating that the metabolic dysfunction observed in these conditions may share common underlying mechanisms. By unraveling the complex mechanisms underlying cardiac metabolism, we aim to contribute to the development of novel therapeutic strategies for metabolic diseases and improve overall cardiovascular health.

High purity of human secreted phospholipase A2 group IIE in Pichia pastoris using basal salts medium comparison with YPD medium

Secreted phospholipase A2s (sPLA2s) are a group of enzymes with 6-8 disulfide bonds that participate in numerous physiological processes by catalyzing the hydrolysis of phospholipids at the sn-2 position. Due to their high content of disulfide bonds and hydrolytic activity toward cell membranes, obtaining the protein of sPLA2s in the soluble and active form is challenging, which hampers their functional study. In this study, one member of recombinant human sPLA2s, tag-free group IIE (GIIE), was expressed in Pichia pastoris. The protein GIIE was purified from the crude culture supernatant by a two-step chromatography procedure, a combination of cation exchange and size-exclusion chromatography. In the shake flask fermentation, Protein of GIIE with higher purity was successfully obtained, using basal salts medium (BSM) instead of YPD medium. In the large-scale fermentation, each liter of BSM produced a final yield of 1.2 mg pure protein GIIE. This protocol will facilitate further research of GIIE and provide references for the production of other sPLA2 members.

VLDL Biogenesis and Secretion: It Takes a Village

The production and secretion of VLDLs (very-low-density lipoproteins) by hepatocytes has a direct impact on liver fat content, as well as the concentrations of cholesterol and triglycerides in the circulation and thus affects both liver and cardiovascular health, respectively. Importantly, insulin resistance, excess caloric intake, and lack of physical activity are associated with overproduction of VLDL, hepatic steatosis, and increased plasma levels of atherogenic lipoproteins. Cholesterol and triglycerides in remnant particles generated by VLDL lipolysis are risk factors for atherosclerotic cardiovascular disease and have garnered increasing attention over the last few decades. Presently, however, increased risk of atherosclerosis is not the only concern when considering today's cardiometabolic patients, as they often also experience hepatic steatosis, a prevalent disorder that can progress to steatohepatitis and cirrhosis. This duality of metabolic risk highlights the importance of understanding the molecular regulation of the biogenesis of VLDL, the lipoprotein that transports triglycerides and cholesterol out of the liver. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL by hepatocytes, which has led to many exciting new molecular insights that are the topic of this review. Increasing our understanding of the biology of this pathway will aid to the identification of novel therapeutic targets to improve both the cardiovascular and the hepatic health of cardiometabolic patients. This review focuses, for the first time, on this duality.

IL32 downregulation lowers triglycerides and type I collagen in di-lineage human primary liver organoids

Steatotic liver disease (SLD) prevails as the most common chronic liver disease yet lack approved treatments due to incomplete understanding of pathogenesis. Recently, elevated hepatic and circulating interleukin 32 (IL-32) levels were found in individuals with severe SLD. However, the mechanistic link between IL-32 and intracellular triglyceride metabolism remains to be elucidated. We demonstrate in vitro that incubation with IL-32β protein leads to an increase in intracellular triglyceride synthesis, while downregulation of IL32 by small interfering RNA leads to lower triglyceride synthesis and secretion in organoids from human primary hepatocytes. This reduction requires the upregulation of Phospholipase A2 group IIA (PLA2G2A). Furthermore, downregulation of IL32 results in lower intracellular type I collagen levels in di-lineage human primary hepatic organoids. Finally, we identify a genetic variant of IL32 (rs76580947) associated with lower circulating IL-32 and protection against SLD measured by non-invasive tests. These data suggest that IL32 downregulation may be beneficial against SLD.

Atypical formations of gintonin lysophosphatidic acids as new materials and their beneficial effects on degenerative diseases

Fresh ginseng is prone to spoilage due to its high moisture content. For long-term storage, most fresh ginsengs are dried to white ginseng (WG) or steamed for hours at high temperature/pressure and dried to form Korean Red ginseng (KRG). They are further processed for ginseng products when subjected to hot water extraction/concentration under pressure. These WG or KRG preparation processes affect ginsenoside compositions and also other ginseng components, probably during treatments like steaming and drying, to form diverse bioactive phospholipids. It is known that ginseng contains high amounts of gintonin lysophosphatidic acids (LPAs). LPAs are simple lipid-derived growth factors in animals and humans and act as exogenous ligands of six GTP-binding-protein coupled LPA receptor subtypes. LPAs play diverse roles ranging from brain development to hair growth in animals and humans. LPA-mediated signaling pathways involve various GTP-binding proteins to regulate downstream pathways like [Ca2+]i transient induction. Recent studies have shown that gintonin exhibits anti-Alzheimer's disease and anti-arthritis effects in vitro and in vivo mediated by gintonin LPAs, the active ingredients of gintonin, a ginseng-derived neurotrophin. However, little is known about how gintonin LPAs are formed in high amounts in ginseng compared to other herbs. This review introduces atypical or non-enzymatic pathways under the conversion of ginseng phospholipids into gintonin LPAs during steaming and extraction/concentration processes, which exert beneficial effects against degenerative diseases, including Alzheimer's disease and arthritis in animals and humans via LPA receptors.

Localization and expression of phospholipase A2 and polyunsaturated fatty acid profile in the testis tissues of Hu sheep

The fatty acid content and the localization and expression of phospholipase A2 (PLA2) in the testis of Hu sheep were investigated. A total of 18 six-month-old Hu sheep were divided into small group (S, with left testis weight < 50 g), medium group (M, with left testis weight among 90-110 g), and large group (L, with left testis weight >160 g), which had six individuals each. The expression of PLA2 in testicular tissues of different sizes was analyzed by immunohistochemistry, RT-qPCR, and Western blot. The fatty acid profile was detected by gas chromatography. Immunohistochemical labeling determined that PLA2 protein was expressed in the Leydig and Sertoli cells of testis, and the immunohistochemical average optional density in the S group was significantly greater than the L group (P < 0.05). RT-qPCR and Western blot analysis showed that PLA2 in the S group was greater than that in the L group (P < 0.05). Docosahexaenoic acid, ω-3 polyunsaturated fatty acid (PUFA), and total PUFA content in the testis of the L group were significantly less than those of the S and M groups (P < 0.01). This study showed that PLA2 content in the S group was greater than that in the L group.

Phospholipase D1 activity is crucial for cytosolic phospholipase A2 -dependent prostaglandin E2 formation in murine osteoblastic MC3T3-E1 cells

In bone, prostaglandin E2 (PGE2) is highly osteogenic and formed by osteoblasts, a key modulatory event in the regulation of bone cell activity. MC3T3-E1 cells are widely used as an in vitro model of osteoblast function. It is still not clear which pathways contribute to the release of AA in these cells. In this study we have focussed on the contribution of phospholipase D (PLD) enzymes to osteoblastic PGE2 formation after stimulation with endothelin-1 (ET-1). Using specific inhibitors of PLD1 and PLD2 we could show that PGE2 formation was strictly dependent on PLD1 but not PLD2 activity and cytosolic phospholipase A2 (cPLA2) was activated by triggering through PLD1. We have identified diacyl glycerol (DAG) as a possible effector molecule which may serve as a triggering signal for PKC activation and subsequent cPLA2 phosphorylation.

Molecular evidence for the adaptive evolution in euryhaline bivalves

Marine bivalves inhabiting intertidal and estuarine areas are frequently exposed to salinity stress due to persistent rainfall and drought. Through prolonged adaptive evolution, numerous bivalves have developed eurysalinity, which are capable of tolerating a wide range of salinity fluctuations through the sophisticated regulation of physiological metabolism. Current research has predominantly focused on investigating the physiological responses of bivalves to salinity stress, leaving a significant gap in our understanding of the adaptive evolutionary characteristics in euryhaline bivalves. Here, comparative genomics analyses were performed in two groups of bivalve species, including 7 euryhaline species and 5 stenohaline species. We identified 24 significantly expanded gene families and 659 positively selected genes in euryhaline bivalves. A significant co-expansion of solute carrier family 23 (SLC23) facilitates the transmembrane transport of ascorbic acids in euryhaline bivalves. Positive selection of antioxidant genes, such as GST and TXNRD, augments the capacity of active oxygen species (ROS) scavenging under salinity stress. Additionally, we found that the positively selected genes were significantly enriched in KEGG pathways associated with carbohydrates, lipids and amino acids metabolism (ALDH, ADH, and GLS), as well as GO terms related to transmembrane transport and inorganic anion transport (SLC22, CLCND, and VDCC). Positive selection of MCT might contribute to prevent excessive accumulation of intracellular lactic acids during anaerobic metabolism. Positive selection of PLA2 potentially promote the removal of damaged membranes lipids under salinity stress. Our findings suggest that adaptive evolution has occurred in osmoregulation, ROS scavenging, energy metabolism, and membrane lipids adjustments in euryhaline bivalves. This study enhances our understanding of the molecular mechanisms underlying the remarkable salinity adaption of euryhaline bivalves.

Secretory phospholipase (sPLA2-IIA) regulates breast cancer stem cells differentiation and metastatic potential

Breast cancer is the second most cancer worldwide in females. The primary factor responsible for tumor recurrence is the presence of breast cancer stem cells (BCSCs), which escape the chemo-radiotherapy. In this study, we have investigated the role of Secretory phospholipase-A2 Group 2A (sPLA2-IIA) that is overexpressed in BCSCs of MCF7 and MDA-MB-231 breast cancer cell lines. Further, overexpression of sPLA2-IIA revealed an increased EGFR/JNK/c-JUN/c-FOS signaling in BCSCs, while sPLA2-IIA knockdown significantly reduced the percentage of BCSCs and decreased signaling in both the cell lines. Importantly, sPLA2-IIA knockdown showed differentiation of BCSCs. Strikingly, PET imaging showed a decreased metastatic potential of BCSCs. Our study revealed a novel role of sPLA2-IIA in regulating BCSCs, which play a crucial role in regulating the differentiation and metastatic potential of BCSCs.

Being Eaten Alive: How Energy-Deprived Cells Are Disposed of, Mediated by C-Reactive Protein-Including a Treatment Option

In medicine, C-reactive protein (CRP) has become established primarily as a biomarker, predicting patient prognosis in many indications. Recently, however, there has been mounting evidence that it causes inflammatory injury. As early as 1999, CRP was shown to induce cell death after acute myocardial infarction (AMI) in rats and this was found to be dependent on complement. The pathological effect of CRP was subsequently confirmed in further animal species such as rabbit, mouse and pig. A conceptual gap was recently closed when it was demonstrated that ischemia in AMI or ischemia/hypoxia in the severe course of COVID-19 causes a drastic lack of energy in involved cells, resulting in an apoptotic presentation because these cells cannot repair/flip-flop altered lipids. The deprivation of energy leads to extensive expression on the cell membranes of the CRP ligand lysophosphatidylcholine. Upon attachment of CRP to this ligand, the classical complement pathway is triggered leading to the swift elimination of viable cells with the appearance of an apoptotic cell by phagocytes. They are being eaten alive. This, consequently, results in substantial fibrotic remodeling within the involved tissue. Inhibiting this pathomechanism via CRP-targeting therapy has been shown to be beneficial in different indications.

Recent advances in extracellular vesicles in gastrointestinal cancer and lymphoma

Extracellular vesicles (EVs) are intercellular communication agents that transfer microRNAs (miRNAs), other non-coding RNAs (ncRNAs), messenger RNAs (mRNAs), proteins, lipids, metabolites, and other molecules from donor cells (e.g., cancer cells) to recipient cells (e.g., stromal cells). In 2007, miRNAs were reported to be abundant among the ncRNAs present in EVs. Since then, many studies have investigated the functions of miRNAs and have attempted to apply these molecules to aid in the diagnosis and treatment of cancer. Research on EVs has expanded, particularly in the field of cancer, because cancer cells heavily secrete EVs. The cargo of these EVs, especially those in small EVs, such as exosomes, is assumed to work cooperatively and significantly in the tumor microenvironment and to promote metastasis. In this review, we first summarize recent studies on EVs in gastrointestinal cancer and highlight studies on human satellite II RNAs, which are a type of ncRNA found in EVs that possess repetitive sequences. Second, since several recent studies have revealed that phospholipids, which are components of EV membranes, play important roles in intercellular communication and the generation of lipid mediators in the tumor microenvironment, we review the reported roles of these molecules and discuss their potential use in the design of new cancer treatments.

Exploring the potential effect of phospholipase A2 antibody to extend beef shelf-life in a beef liposome model system

The objective of this study was to elucidate the effect of phospholipase A2 (PLA2) and a PLA2 antibody (aPLA2) on phospholipid (PL) hydrolysis in beef and to understand how the altered PL composition may affect lipid oxidation and antioxidant capacity of beef in an in vitro system. Various combinations of PLA2 and aPLA2 were introduced to a beef liposome model system and exposed to a retail display. The PL and free fatty acid (FFA) profiles, antioxidant capacity and lipid oxidation were measured for the liposome system. Key PL classes were reduced and the release of polyunsaturated FFAs was increased with the inclusion of PLA2 in the treatments (P < 0.05). There was no inhibition of PL hydrolysis with the addition of aPLA2. PLA2 showed strong antioxidant capacity in the liposome system (P < 0.01), but lipid oxidation still increased in samples treated with PLA2 throughout the retail display (P < 0.01). Finally, aPLA2 treatments demonstrated potential to decrease lipid oxidation (P < 0.01).

Parasitic nematode secreted phospholipase A2 suppresses cellular and humoral immunity by targeting hemocytes in Drosophila melanogaster

A key aspect of parasitic nematode infection is the nematodes' ability to evade and/or suppress host immunity. This immunomodulatory ability is likely driven by the release of hundreds of excretory/secretory proteins (ESPs) during infection. While ESPs have been shown to display immunosuppressive effects on various hosts, our understanding of the molecular interactions between individual proteins released and host immunity requires further study. We have recently identified a secreted phospholipase A2 (sPLA2) released from the entomopathogenic nematode (EPN) Steinernema carpocapsae we have named Sc-sPLA2. We report that Sc-sPLA2 increased mortality of Drosophila melanogaster infected with Streptococcus pneumoniae and promoted increased bacterial growth. Furthermore, our data showed that Sc-sPLA2 was able to downregulate both Toll and Imd pathway-associated antimicrobial peptides (AMPs) including drosomycin and defensin, in addition to suppressing phagocytosis in the hemolymph. Sc-sPLA2 was also found to be toxic to D. melanogaster with the severity being both dose- and time-dependent. Collectively, our data highlighted that Sc-sPLA2 possessed both toxic and immunosuppressive capabilities.

Secretory Phospholipases A2, from Snakebite Envenoming to a Myriad of Inflammation Associated Human Diseases-What Is the Secret of Their Activity?

Secreted phospholipases of type A2 (sPLA2s) are proteins of 14-16 kDa present in mammals in different forms and at different body sites. They are involved in lipid transformation processes, and consequently in various immune, inflammatory, and metabolic processes. sPLA2s are also major components of snake venoms, endowed with various toxic and pharmacological properties. The activity of sPLA2s is not limited to the enzymatic one but, through interaction with different types of molecules, they exert other activities that are still little known and explored, both outside and inside the cells, as they can be endocytosed. The aim of this review is to analyze three features of sPLA2s, yet under-explored, knowledge of which could be crucial to understanding the activity of these proteins. The first feature is their disulphide bridge pattern, which has always been considered immutable and necessary for their stability, but which might instead be modulable. The second characteristic is their ability to undergo various post-translational modifications that would control their interaction with other molecules. The third feature is their ability to participate in active molecular condensates both on the surface and within the cell. Finally, the implications of these features in the design of anti-inflammatory drugs are discussed.

Multimodal regulation of the osteoclastogenesis process by secreted group IIA phospholipase A2

Increasing evidence points to the involvement of group IIA secreted phospholipase A₂ (sPLA₂-IIA) in pathologies characterized by abnormal osteoclast bone-resorption activity. Here, the role of this moonlighting protein has been deepened in the osteoclastogenesis process driven by the RANKL cytokine in RAW264.7 macrophages and bone-marrow derived precursor cells from BALB/cJ mice. Inhibitors with distinct selectivity toward sPLA₂-IIA activities and recombinant sPLA₂-IIA (wild-type or catalytically inactive forms, full-length or partial protein sequences) were instrumental to dissect out sPLA₂-IIA function, in conjunction with reduction of sPLA₂-IIA expression using small-interfering-RNAs and precursor cells from Pla2g2a knock-out mice. The reported data indicate sPLA₂-IIA participation in murine osteoclast maturation, control of syncytium formation and resorbing activity, by mechanisms that may be both catalytically dependent and independent. Of note, these studies provide a more complete understanding of the still enigmatic osteoclast multinucleation process, a crucial step for bone-resorbing activity, uncovering the role of sPLA₂-IIA interaction with a still unidentified receptor to regulate osteoclast fusion through p38 SAPK activation. This could pave the way for the design of specific inhibitors of sPLA₂-IIA binding to interacting partners implicated in osteoclast syncytium formation.

Cervical sympathetic trunk transection alleviates acute lung injury caused by intestinal obstruction via inhibition of phospholipase A2 in rats

Background

Intestinal obstruction can result in inflammatory injury to distant organs, especially the lungs. Stellate ganglion block (SGB) provides sympathetic nervous homeostasis and inhibits the systemic inflammatory response. This study aimed to investigate whether SGB can alleviate acute lung injury by inhibiting phospholipase A₂ expression in rats.

Methods

Thirty healthy male Sprague–Dawley rats were divided into three groups: C group (sham-operated); CLP group (cecal ligation and puncture with intestinal obstruction), and cervical sympathetic trunk transection (CSTT) group (transection of the cervical sympathetic trunk following CLP).Arterial blood samples were obtained to determine the ratio of partial arterial pressure of oxygen (PaO₂) to fraction of oxygen in inspired air (FiO₂). Venous blood samples were used to evaluate the serum concentrations of chemokines, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 using enzyme-linked immunosorbent assays. Following euthanasia, the lungs were isolated to estimate the wet/dry lung weight (W/D) ratio, evaluate the pathological damage to lung tissues on microscopy, and determine secretory-type phospholipase A₂ (sPLA₂) expression using western blotting.

Results

Rats in the CLP group showed increased fatigue, decreased activity levels, and coarse, gray hair. The levels of chemokines, TNF-α, and IL-6 in the CLP and CSTT groups were higher than those in the C group. However, the levels were lower in the CSTT group than those in the CLP group. IL-10 levels in the CLP group were higher and lower than those in the C and CSTT groups, respectively. W/D ratios and PaO₂/FiO₂ in the CLP and CSTT groups were higher than those in the C group, whereas these ratios in the CSTT group were lower than those in the CLP group. No lung injury was noted in group C, and the lung injury scores were lower in the CSTT group than those in the CLP group. sPLA₂ expression levels in the CLP group were higher than those in the C group, whereas these levels in the CSTT group were lower than those in the CLP group.

Conclusions

sPLA₂ overexpression in the lungs may be a pathogenic factor in acute lung injury. CSTT alleviated acute lung injury by inhibiting sPLA₂ expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01814-2.

Platelet extracellular vesicles and the secretory interactome join forces in health and disease

Extracellular vesicles (EVs) are small membrane-bound vesicles released by cells under various conditions. They are found in the extracellular milieu in all biological fluids. As the concentrations, contents, and origin of EVs can change during inflammation, the assessment of EVs can be used as a proxy of cellular activation. Here, we review the literature regarding EVs, more particularly those released by platelets and their mother cells, the megakaryocytes. Their cargo includes cytokines, growth factors, organelles (mitochondria and proteasomes), nucleic acids (messenger and non-coding RNA), transcription factors, and autoantigens. EVs may thus contribute to intercellular communication by facilitating exchange of material between cells. EVs also interact with other molecules secreted by cells. In autoimmune diseases, EVs are associated with antibodies secreted by B cells. By definition, EVs necessarily comprise a phospholipid moiety, which is thus the target of secreted phospholipases also abundantly expressed in the extracellular milieu. We discuss how platelet-derived EVs, which represent the majority of the circulating EVs, may contribute to immunity through the activity of their cargo or in combination with the secretory interactome.

Metabolites of gut microbiota fermenting Poria cocos polysaccharide alleviates chronic nonbacterial prostatitis in rats

Chronic nonbacterial prostatitis (CNP) is a common urology disease. Our previous research found Poria cocos polysaccharides (PPs) alleviated CNP and suggested the effect was related to gut bacteria. We investigated the crucial bacteria and their metabolites responsible for the anti-CNP effect to discover possible mechanisms. The results showed that after the fermentation of PPs by human fecal microbiota, Parabacteroides, Fusicatenibacter, and Parasutterella were significantly enriched. Haloperidol glucuronide and 7-ketodeoxycholic acid generated by these bacteria could be responsible for the increased expression of Alox15 and Pla2g2f and the reduced expression of Cyp1a1 and Hsd17b7 in colon epithelium. The ratio of dihydrotestosterone to estradiol in serum was regulated, and CNP was alleviated. Our results suggested that Parabacteroides, Fusicatenibacter, and Parasutterella could be the essential bacteria in CNP alleviation and their metabolites of PPs 7-ketodeoxycholic acid and haloperidol glucuronide could be the signal molecules of the "gut-prostate axis".

Associations of genetic variants of lysophosphatidylcholine metabolic enzymes with levels of serum lipids

OBJECTIVE

Metabolic disturbance of lysophosphatidylcholine (LPC) is related with dyslipidemia. Therefore, eight single-nucleotide polymorphisms (SNPs) were selected from LPC metabolic enzymes to study their associations with obesity and serum levels of lipids.

METHODS

A total of 3305 children were recruited from four independent studies. Eight SNPs of LPC metabolic enzymes were selected and genotyped with the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The multivariable linear regression model was applied to detect the associations of eight SNPs with obesity-related phenotypes and levels of lipids in each study. Meta-analyses were used to combine the results of four studies.

RESULTS

Only SNP rs4420638 of APOC-1 gene was associated with serum lipids even after Bonferroni correction. The rs4420638 was positively associated with TC (β = 0.15, P = 8.59 × 10^-9) and low-density-lipoprotein-cholesterol (LDL-C, β = 0.16, P = 9.98 × 10^-14) individually.

CONCLUSION

The study firstly revealed the association between APOC-1/rs4420638 and levels of serum lipids in Chinese children, providing evidence for susceptible gene variants of dyslipidemia.

[CRP apheresis in acute myocardial infarction and COVID-19]

C‑reactive protein (CRP) is the best-known acute phase protein. In humans, inflammation and infection are usually accompanied by an increase in CRP levels in the blood, which is why CRP is an important biomarker in daily clinical routine. CRP can mediate the initiation of phagocytosis by labeling damaged cells. This labeling leads to activation of the classical complement pathway (up to C4) and ends in the elimination of pathogens or reversibly damaged or dead cells. This seems to make sense in case of an external wound of the body. However, in the case of "internal wounds" (e.g., myocardial infarction, stroke), CRP induces tissue damage to potentially regenerable tissue by cell labeling, which has corresponding deleterious effects on cardiac and brain tissue or function. The described labeling of ischemic but potentially regenerable cells by CRP apparently also occurs in coronavirus disease 2019 (COVID-19). Parts of the lung become ischemic due to intra-alveolar edema and hemorrhage, and this is accompanied by a dramatic increase in CRP. Use of selective immunoadsorption of CRP from blood plasma ("CRP apheresis") to rapidly and efficiently lower the fulminant CRP load in the body fills this pharmacotherapeutic gap. With CRP apheresis, it is possible for the first time to remove this pathological molecule quickly and efficiently in clinical practice.

Secretory phospholipase sPLA2-IIAloss impairs tumorigenic and metastatic potential in breast cancer cells

Breast cancer stem cells (BCSCs) are slow cycling cells that escape the traditional chemo-radio-therapy, thereby contributing in resistance and recurrence. Although several markers have been identified, it is still challenging to develop strategies targeting them. In this study, we have isolated BCSCs from MCF-7 cell line using markers CD44+/CD24-/low, which showed higher percentage of mammospheres in CSC population. Moreover, in vivo tumorigenic potential of BCSCs showed as low as 10,000 cells had the ability to develop tumors when transplanted into NOD-SCID mice. We observed an increased level of EMT markers in CSC population. Overexpression of secretory phospholipase sPLA2-IIA was found in CSCs. Further, we have uncovered the upregulation of sPLA2-IIA mediated through JNK signaling in breast cancer cells whereas knockdown of sPLA2-IIA reduces JNK signaling, cell proliferation, EMT and in vivo tumorigenic potential in breast cancer cells. Our study reveals overexpression of sPLA2-IIA in two different breast cancer cells such as MCF7 (ER+,PR+) and a triple negative, MDA-MB-231 (ER-PR-HER2-). Further, the novel role of sPLA2-IIA was discerned by unraveling the molecular mechanism, which regulates the cell proliferation and metastasis in breast cancer cells.

Integrating Metabolomics and Network Pharmacology to Explore the Protective Effect of Ginsenoside Re against Radiotherapy Injury in Mice

Ionizing radiation (IR) can cause radiation damage, mutagenesis, or carcinogenesis in the irradiated subject. It is manifested as metabolic disorders of the body and damage to the immune system, nervous system, and endocrine system, which can lead to physiological and pathological changes and endogenous metabolic disorders. Ginsenoside Re (G-Re), a single component of traditional Chinese medicine, has a certain ameliorating effect on radiation damage. However, its mechanism of action in the treatment of radiotherapy injury remains unclear. With this purpose, the hematopoietic function of mice damaged by X-ray radiation was studied, and the protective effect of G-Re on mice damaged by radiation was preliminarily evaluated. Network pharmacology and metabolomics analysis are used to further reveal the mechanism of G-Re to improve radiation damage through metabolomics research. Results of metabolomics analysis showed that 16 potential biomarkers were identified as participating in the therapeutic effect of G-Re on IR. Most of these metabolites are adjusted to recover after G-Re treatment. The pathways involved included glycerophospholipid metabolism, sphingolipid metabolism, and linoleic acid metabolism. According to network pharmacology analysis, we found 10 hub genes, which is partly consistent with the findings of metabolomics. Further comprehensive analysis focused on 4 key targets, including SRC, EGFR, AKT1, and MAPK8, and their related core metabolites and pathways. This study combines metabolomics and network pharmacology analysis to explore the key targets and mechanisms of G-Re in the treatment of IR, in order to provide new strategies for clinical treatment of radiotherapy injury.

The Anti-Allergic and Anti-Inflammatory Effects of Phlorotannins from the Edible Brown Algae, Ecklonia sp. and Eisenia sp

Because the number of people suffering from allergies has significantly increased, improved ways of treating these conditions by medical, pharmaceutical, and dietary means are required. Large numbers of studies on allergy have been conducted, and many anti-allergic compounds have been found. Phenolic compounds from terrestrial plants, including catechins and flavonoids, possess anti-allergic properties. Although polyphenols are present in some brown algae, their anti-allergic activities were not studied in detail before the 1990s. The focus was on the algal polyphenols, collectively called phlorotannins (eg., eckol, 6,6′-bieckol, 8,8′-bieckol, dieckol, and phlorofucofuroeckol-A), and research was conducted to clarify their anti-allergic activities. This review summarizes the anti-allergic effects of phlorotannins isolated from the brown alga, Eisenia nipponica, and related reports by other research groups.

Identification and expression of phospholipase A2 genes related to transcriptional control in the interleukin-17A/F1 pathway in the intestines of Japanese medaka Oryzias latipes

Phospholipase A2 (PLA2), a phospholipid hydrolase, has recently attracted attention owing to its broad functionality. Immunological evidence has revealed increased susceptibility to infectious diseases and immunodeficiency in knockout (KO) mice of several pla2 genes. However, no progress has been made in terms of immunological research on any pla2 gene in fish. In this study, we focused on the intestinal immune responses of fish PLA2s. The full-length open reading frames of pla2g1b, pla2g3, pla2g10, pla2g12b1, pla2g12b2, and pla2g15 cDNAs were cloned in Japanese medaka (Orizias latipes), and their gene expressions were quantified by real-time PCR (qPCR) and in situ hybridization (ISH). Characterization of pla2 genes revealed a functional domain and three-dimensional structure similar to the mammalian counterparts. In addition, expression of pla2g1b, pla2g12b1, and pla2g12b2 was extremely high in Japanese medaka intestines. ISH detected strong expression of pla2g1b mRNAs in the basal muscle layer, and pla2g12b1 and pla2g12b2 mRNAs were detected in the epithelial cells. In the medaka exposed to Edwardsiella piscicida, pla2g12b1, pla2g12b2 and pla2g15 were significantly induced in the anterior and posterior intestines, and pla2g1b was upregulated in the anterior intestine. Furthermore, pla2g1b, pla2g3, pla2g10, and pla2g12b2 were significantly downregulated in the IL-17A/F1 KO medaka compared to those in wild-type medaka. These results suggest that these PLA2s are involved in intestinal immunity in teleosts.

Lure-and-kill macrophage nanoparticles alleviate the severity of experimental acute pancreatitis

Acute pancreatitis is a disease associated with suffering and high lethality. Although the disease mechanism is unclear, phospholipase A2 (PLA2) produced by pancreatic acinar cells is a known pathogenic trigger. Here, we show macrophage membrane-coated nanoparticles with a built-in 'lure and kill' mechanism (denoted 'MΦ-NP(L&K)') for the treatment of acute pancreatitis. MΦ-NP(L&K) are made with polymeric cores wrapped with natural macrophage membrane doped with melittin and MJ-33. The membrane incorporated melittin and MJ-33 function as a PLA2 attractant and a PLA2 inhibitor, respectively. These molecules, together with membrane lipids, work synergistically to lure and kill PLA2 enzymes. These nanoparticles can neutralize PLA2 activity in the sera of mice and human patients with acute pancreatitis in a dose-dependent manner and suppress PLA2-induced inflammatory response accordingly. In mouse models of both mild and severe acute pancreatitis, MΦ-NP(L&K) confer effective protection against disease-associated inflammation, tissue damage and lethality. Overall, this biomimetic nanotherapeutic strategy offers an anti-PLA2 treatment option that might be applicable to a wide range of PLA2-mediated inflammatory disorders.

Pathophysiological regulation of lung function by the free fatty acid receptor FFA4

Increased prevalence of inflammatory airway diseases including asthma and chronic obstructive pulmonary disease (COPD) together with inadequate disease control by current frontline treatments means that there is a need to define therapeutic targets for these conditions. Here, we investigate a member of the G protein-coupled receptor family, FFA4, that responds to free circulating fatty acids including dietary omega-3 fatty acids found in fish oils. We show that FFA4, although usually associated with metabolic responses linked with food intake, is expressed in the lung where it is coupled to G_q/11 signaling. Activation of FFA4 by drug-like agonists produced relaxation of murine airway smooth muscle mediated at least in part by the release of the prostaglandin E₂ (PGE₂) that subsequently acts on EP₂ prostanoid receptors. In normal mice, activation of FFA4 resulted in a decrease in lung resistance. In acute and chronic ozone models of pollution-mediated inflammation and house dust mite and cigarette smoke-induced inflammatory disease, FFA4 agonists acted to reduce airway resistance, a response that was absent in mice lacking expression of FFA4. The expression profile of FFA4 in human lung was similar to that observed in mice, and the response to FFA4/FFA1 agonists similarly mediated human airway smooth muscle relaxation ex vivo. Our study provides evidence that pharmacological targeting of lung FFA4, and possibly combined activation of FFA4 and FFA1, has in vivo efficacy and might have therapeutic value in the treatment of bronchoconstriction associated with inflammatory airway diseases such as asthma and COPD.

A Metalloproteinase Induces an Inflammatory Response in Preadipocytes with the Activation of COX Signalling Pathways and Participation of Endogenous Phospholipases A2

Matrix metalloproteinases (MMPs) are proteolytic enzymes that have been associated with the pathogenesis of inflammatory diseases and obesity. Adipose tissue in turn is an active endocrine organ capable of secreting a range of proinflammatory mediators with autocrine and paracrine properties, which contribute to the inflammation of adipose tissue and adjacent tissues. However, the potential inflammatory effects of MMPs in adipose tissue cells are still unknown. This study investigates the effects of BmooMPα-I, a single-domain snake venom metalloproteinase (SVMP), in activating an inflammatory response by 3T3-L1 preadipocytes in culture, focusing on prostaglandins (PGs), cytokines, and adipocytokines biosynthesis and mechanisms involved in prostaglandin E2 (PGE2) release. The results show that BmooMPα-I induced the release of PGE2, prostaglandin I2 (PGI2), monocyte chemoattractant protein-1 (MCP-1), and adiponectin by preadipocytes. BmooMPα-I-induced PGE2 biosynthesis was dependent on group-IIA-secreted phospholipase A2 (sPLA2-IIA), cytosolic phospholipase A2-α (cPLA2-α), and cyclooxygenase (COX)-1 and -2 pathways. Moreover, BmooMPα-I upregulated COX-2 protein expression but not microsomal prostaglandin E synthase-1 (mPGES-1) expression. In addition, we demonstrate that the enzymatic activity of BmooMPα-I is essential for the activation of prostanoid synthesis pathways in preadipocytes. These data highlight preadipocytes as important targets for metalloproteinases and provide new insights into the contribution of these enzymes to the inflammation of adipose tissue and tissues adjacent to it.

Non-coding RNAs and lipids mediate the function of extracellular vesicles in cancer cross-talk

Research on extracellular vesicles (EVs) has been expanded, especially in the field of cancer. The cargoes in EVs, especially those in small EVs such as exosomes include microRNAs (miRNAs), mRNA, proteins, and lipids, are assumed to work cooperatively in the tumor microenvironment. In 2007, it was reported that miRNAs were abundant among the non-coding RNAs present in exosomes. Since then, many studies have investigated the functions of miRNAs and have tried to apply these molecules to aid in the diagnosis of cancer. Accordingly, many reviews of non-coding RNAs in EVs have been published for miRNAs. This review focuses on relatively new cargoes, covering long noncoding (lnc) RNAs, circular RNAs, and repeat RNAs, among non-coding RNAs. These RNAs, regardless of EV or cell type, have newly emerged due to the innovation of sequencing technology. The poor conservation, low quantity, and technical difficulty in detecting these RNA types have made it difficult to elucidate their functions and expression patterns. We herein summarize a limited number of studies. Although lipids are major components of EVs, current research on EVs focuses on miRNA and protein biology, while the roles of lipids in exosomes have not drawn attention. However, several recent studies revealed that phospholipids, which are components of the EV membrane, play important roles in the intercommunication between cells and in the generation of lipid mediators. Here, we review the reported roles of these molecules, and describe their potential in cancer biology.

The atypical binding mechanism of second calcium on phospholipase A2 group IIE

Secreted phospholipase A2s (sPLA2s) are calcium dependent enzymes involved in various biological events such as lipid metabolism and inflammation. We previously identified the second calcium (Ca2) binding site of human sPLA2 Group IIE (hGIIE) by structural study and suggested that Asn21 act as the switch of Ca2 binding to modulate the enzymatic activity, but the detailed Ca2 binding mechanism is still unclear. Combined with enzymatic assay, model analysis and calcium binding affinity data for mutated hGIIE proteins, we herein further demonstrate that the flexibly bound Ca2 is essential for the catalysis of hGIIE, unlike the stable binding of Ca2 in hGIIA that replenishes the calcium in the typical loop during the reaction. The atypical Ca2 binding feature of hGIIE will provide a better understanding on the catalytic mechanism of hGIIE.

Short Linear Motifs Characterizing Snake Venom and Mammalian Phospholipases A2

Snake venom phospholipases A2 (PLA2s) have sequences and structures very similar to those of mammalian group I and II secretory PLA2s, but they possess many toxic properties, ranging from the inhibition of coagulation to the blockage of nerve transmission, and the induction of muscle necrosis. The biological properties of these proteins are not only due to their enzymatic activity, but also to protein–protein interactions which are still unidentified. Here, we compare sequence alignments of snake venom and mammalian PLA2s, grouped according to their structure and biological activity, looking for differences that can justify their different behavior. This bioinformatics analysis has evidenced three distinct regions, two central and one C-terminal, having amino acid compositions that distinguish the different categories of PLA2s. In these regions, we identified short linear motifs (SLiMs), peptide modules involved in protein–protein interactions, conserved in mammalian and not in snake venom PLA2s, or vice versa. The different content in the SLiMs of snake venom with respect to mammalian PLA2s may result in the formation of protein membrane complexes having a toxic activity, or in the formation of complexes whose activity cannot be blocked due to the lack of switches in the toxic PLA2s, as the motif recognized by the prolyl isomerase Pin1.

Progression from Monoclonal gammopathy of undetermined significance of the immunoglobulin M class (IgM-MGUS) to Waldenstrom Macroglobulinemia is associated with an alteration in lipid metabolism

The molecular events that modulate the progression of monoclonal gammopathy of undetermined significance of the immunoglobulin M class (IgM-MGUS) to Waldenstrom Macroglobulinemia (WM) are mostly unknown. We implemented comparative proteomics and metabolomics analyses on patient serum samples to identify differentially expressed molecules crucial to the progression from IgM-MGUS to WM. Our data identified altered lipid metabolism as a discriminating factor between MGUS, WM, and matched normal controls. Levels of many fatty acids, including polyunsaturated fatty acids and dicarboxylic acids, were significantly downregulated in WM sera when compared to MGUS. These reductions were associated with diminished 15-LOX and PPAR protein expression and increased 5-LOX and GPX4 expression in WM versus MGUS patients’ samples. Furthermore, WM serum samples showed increased lipid peroxidation compared to MGUS. Treatment with IL-6 or TNFα, upstream regulators of differentially expressed proteins between MGUS and WM, increased lipid absorption and lipid peroxidation in WM cell lines. Knock-down of 15-LOX expression increased WM cell survival, an effect accompanied by increased 5-LOX and GPX4 expression. In summary, our data show that reduced fatty acid and lipid metabolite levels in the serum of the WM patients are associated with increased lipid peroxidation and that downregulation of 15-LOX increases the survival of WM cells. These data are highly significant in identifying the biomarkers of disease progression and designing targeted therapeutic intervention.

C-Reactive Protein Triggers Cell Death in Ischemic Cells

C-reactive protein (CRP) is the best-known acute phase protein. In humans, almost every type of inflammation is accompanied by an increase of CRP concentration. Until recently, the only known physiological function of CRP was the marking of cells to initiate their phagocytosis. This triggers the classical complement pathway up to C4, which helps to eliminate pathogens and dead cells. However, vital cells with reduced energy supply are also marked, which is useful in the case of a classical external wound because an important substrate for pathogens is disposed of, but is counterproductive at internal wounds (e.g., heart attack or stroke). This mechanism negatively affects clinical outcomes since it is established that CRP levels correlate with the prognosis of these indications. Here, we summarize what we can learn from a clinical study in which CRP was adsorbed from the bloodstream by CRP-apheresis. Recently, it was shown that CRP can have a direct effect on blood pressure in rabbits. This is interesting in regard to patients with high inflammation, as they often become tachycardic and need catecholamines. These two physiological effects of CRP apparently also occur in COVID-19. Parts of the lung become ischemic due to intra-alveolar edema and hemorrhage and in parallel CRP increases dramatically, hence it is assumed that CRP is also involved in this ischemic condition. It is meanwhile considered that most of the damage in COVID-19 is caused by the immune system. The high amounts of CRP could have an additional influence on blood pressure in severe COVID-19.

Reorganization of Metabolism during Cardiomyogenesis Implies Time-Specific Signaling Pathway Regulation

Understanding the cell differentiation process involves the characterization of signaling and regulatory pathways. The coordinated action involved in multilevel regulation determines the commitment of stem cells and their differentiation into a specific cell lineage. Cellular metabolism plays a relevant role in modulating the expression of genes, which act as sensors of the extra-and intracellular environment. In this work, we analyzed mRNAs associated with polysomes by focusing on the expression profile of metabolism-related genes during the cardiac differentiation of human embryonic stem cells (hESCs). We compared different time points during cardiac differentiation (pluripotency, embryoid body aggregation, cardiac mesoderm, cardiac progenitor and cardiomyocyte) and showed the immature cell profile of energy metabolism. Highly regulated canonical pathways are thoroughly discussed, such as those involved in metabolic signaling and lipid homeostasis. We reveal the critical relevance of retinoic X receptor (RXR) heterodimers in upstream retinoic acid metabolism and their relationship with thyroid hormone signaling. Additionally, we highlight the importance of lipid homeostasis and extracellular matrix component biosynthesis during cardiomyogenesis, providing new insights into how hESCs reorganize their metabolism during in vitro cardiac differentiation.

Maternal vitamin D deficiency influences long-chain polyunsaturated fatty acids and pregnancy outcome in association with alterations in one-carbon metabolism

Preeclampsia is a pregnancy-specific disorder, leading to maternal and infant morbidity and mortality. Abnormal placentation has been reported in preeclampsia. Nutrients like vitamin D and long-chain polyunsaturated fatty acids (LCPUFA) are known to play a role in placental development. In an animal model, we have previously demonstrated that maternal vitamin D deficiency increases the thromboxane/prostacyclin ratio and contributes to inflammation and vasoconstriction. We hypothesize that maternal vitamin D status influences placental LCPUFA metabolism through alterations in one carbon metabolism in women with preeclampsia. To test this hypothesis, we recruited 69 normotensive control (NC) women and 50 women with preeclampsia. Women with preeclampsia had lower placental protein and mRNA levels of cystathionine-β-synthase (CBS), higher plasma malondialdehyde (MDA) levels and higher levels of arachidonic acid (AA) and total omega-6 fatty acids in the placenta. Women with preeclampsia also demonstrated higher placental mRNA levels of cyclooxygenase-2 (COX-2) as compared to NC women. Maternal 25(OH)D levels were negatively associated with maternal plasma MDA levels. Placental vitamin D receptor (VDR) levels were positively associated with CBS while maternal MDA levels were positively associated with serum levels of thromboxane-B2 (TXB2) levels. Our findings indicate that vitamin D deficiency increases oxidative stress through alterations in one carbon metabolism to influence pro-inflammatory omega-6 metabolic pathway in the placenta. This study demonstrates a possible mechanism through which vitamin D deficiency can result in an imbalance in the LCPUFA metabolites and contribute to placental inflammation and endothelial dysfunction in preeclampsia.

Venom Profiling of the Insular Species Bothrops alcatraz: Characterization of Proteome, Glycoproteome, and N-Terminome Using Terminal Amine Isotopic Labeling of Substrates

Bothrops alcatraz, a species endemic to Alcatrazes Islands, is regarded as critically endangered due to its small area of occurrence and the declining quality of its habitat. We recently reported the identification of N-glycans attached to toxins of Bothrops species, showing similar compositions in venoms of the B. jararaca complex (B. jararaca, B. insularis, and B. alcatraz). Here, we characterized B. alcatraz venom using electrophoretic, proteomic, and glycoproteomic approaches. Electrophoresis showed that B. alcatraz venom differs from B. jararaca and B. insularis; however, N-glycan removal revealed similarities between them, indicating that the occupation of N-glycosylation sites contributes to interspecies variability in the B. jararaca complex. Metalloproteinase was the major toxin class identified in the B. alcatraz venom proteome followed by serine proteinase and C-type lectin, and overall, the adult B. alcatraz venom resembles that of B. jararaca juvenile specimens. The comparative glycoproteomic analysis of B. alcatraz venom with B. jararaca and B. insularis indicated that there may be differences in the utilization of N-glycosylation motifs among their different toxin classes. Furthermore, we prospected for the first time the N-terminome of a snake venom using the terminal amine isotopic labeling of substrates (TAILS) approach and report the presence of ∼30% of N-termini corresponding to truncated toxin forms and ∼37% N-terminal sequences blocked by pyroglutamic acid in B. alcatraz venom. These findings underscore a low correlation between venom gland transcriptomes and proteomes and support the view that post-translational processes play a major role in shaping venom phenotypes.

Secretory Phospholipase A2s in Insulin Resistance and Metabolism

The phospholipases A₂ (PLA₂) superfamily encompasses enzymes commonly found in mammalian tissues and snake venom. Many of these enzymes have unique tissue distribution, function, and substrate specificity suggesting distinct biological roles. In the past, much of the research on secretory PLA₂s has analyzed their roles in inflammation, anti-bacterial actions, and atherosclerosis. In recent studies utilizing a variety of mouse models, pancreatic islets, and clinical trials, a role for many of these enzymes in the control of metabolism and insulin action has been revealed. In this review, this research, and the unique contributions of the PLA₂ enzymes in insulin resistance and metabolism.

A Representative GIIA Phospholipase A2 Activates Preadipocytes to Produce Inflammatory Mediators Implicated in Obesity Development

Adipose tissue secretes proinflammatory mediators which promote systemic and adipose tissue inflammation seen in obesity. Group IIA (GIIA)-secreted phospholipase A₂ (sPLA₂) enzymes are found to be elevated in plasma and adipose tissue from obese patients and are active during inflammation, generating proinflammatory mediators, including prostaglandin E₂ (PGE₂). PGE₂ exerts anti-lipolytic actions and increases triacylglycerol levels in adipose tissue. However, the inflammatory actions of GIIA sPLA₂s in adipose tissue cells and mechanisms leading to increased PGE₂ levels in these cells are unclear. This study investigates the ability of a representative GIIA sPLA₂, MT-III, to activate proinflammatory responses in preadipocytes, focusing on the biosynthesis of prostaglandins, adipocytokines and mechanisms involved in these effects. Our results showed that MT-III induced biosynthesis of PGE₂, PGI₂, MCP-1, IL-6 and gene expression of leptin and adiponectin in preadipocytes. The MT-III-induced PGE₂ biosynthesis was dependent on cytosolic PLA₂ (cPLA₂)-α, cyclooxygenases (COX)-1 and COX-2 pathways and regulated by a positive loop via the EP₄ receptor. Moreover, MT-III upregulated COX-2 and microsomal prostaglandin synthase (mPGES)-1 protein expression. MCP-1 biosynthesis induced by MT-III was dependent on the EP4 receptor, while IL-6 biosynthesis was dependent on EP3 receptor engagement by PGE₂. These data highlight preadipocytes as targets for GIIA sPLA₂s and provide insight into the roles played by this group of sPLA₂s in obesity.

The role of essential fatty acids in cystic fibrosis and normalizing effect of fenretinide

Cystic fibrosis (CF) is the most common autosomal-recessive disease in Caucasians caused by mutations in the CF transmembrane regulator (CFTR) gene. Patients are usually diagnosed in infancy and are burdened with extensive medical treatments throughout their lives. One of the first documented biochemical defects in CF, which predates the cloning of CFTR gene for almost three decades, is an imbalance in the levels of polyunsaturated fatty acids (PUFAs). The principal hallmarks of this imbalance are increased levels of arachidonic acid and decreased levels of docosahexaenoic acids (DHA) in CF. This pro-inflammatory profile of PUFAs is an important component of sterile inflammation in CF, which is known to be detrimental, rather than protective for the patients. Despite decades of intensive research, the mechanistic basis of this phenomenon remains unclear. In this review we summarized the current knowledge on the biochemistry of PUFAs, with a focus on the metabolism of AA and DHA in CF. Finally, a synthetic retinoid called fenretinide (N-(4-hydroxy-phenyl) retinamide) was shown to be able to correct the pro-inflammatory imbalance of PUFAs in CF. Therefore, its pharmacological actions and clinical potential are briefly discussed as well.

Updating Phospholipase A2 Biology

The phospholipase A2 (PLA2) superfamily contains more than 50 enzymes in mammals that are subdivided into several distinct families on a structural and biochemical basis. In principle, PLA2 has the capacity to hydrolyze the sn-2 position of glycerophospholipids to release fatty acids and lysophospholipids, yet several enzymes in this superfamily catalyze other reactions rather than or in addition to the PLA2 reaction. PLA2 enzymes play crucial roles in not only the production of lipid mediators, but also membrane remodeling, bioenergetics, and body surface barrier, thereby participating in a number of biological events. Accordingly, disturbance of PLA2-regulated lipid metabolism is often associated with various diseases. This review updates the current state of understanding of the classification, enzymatic properties, and biological functions of various enzymes belonging to the PLA2 superfamily, focusing particularly on the novel roles of PLA2s in vivo.

Selective Apheresis of C-Reactive Protein for Treatment of Indications with Elevated CRP Concentrations

Almost every kind of inflammation in the human body is accompanied by rising C-reactive protein (CRP) concentrations. This can include bacterial and viral infection, chronic inflammation and so-called sterile inflammation triggered by (internal) acute tissue injury. CRP is part of the ancient humoral immune response and secreted into the circulation by the liver upon respective stimuli. Its main immunological functions are the opsonization of biological particles (bacteria and dead or dying cells) for their clearance by macrophages and the activation of the classical complement pathway. This not only helps to eliminate pathogens and dead cells, which is very useful in any case, but unfortunately also to remove only slightly damaged or inactive human cells that may potentially regenerate with more CRP-free time. CRP action severely aggravates the extent of tissue damage during the acute phase response after an acute injury and therefore negatively affects clinical outcome. CRP is therefore a promising therapeutic target to rescue energy-deprived tissue either caused by ischemic injury (e.g., myocardial infarction and stroke) or by an overcompensating immune reaction occurring in acute inflammation (e.g., pancreatitis) or systemic inflammatory response syndrome (SIRS; e.g., after transplantation or surgery). Selective CRP apheresis can remove circulating CRP safely and efficiently. We explain the pathophysiological reasoning behind therapeutic CRP apheresis and summarize the broad span of indications in which its application could be beneficial with a focus on ischemic stroke as well as the results of this therapeutic approach after myocardial infarction.