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Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis.

ABSTRACT: Acute lipolysis of visceral fat or circulating triglycerides may worsen acute pancreatitis (AP)-associated local and systemic injury. The pancreas expresses pancreatic triacylglycerol lipase (PNLIP), pancreatic lipase-related protein 2 (PNLIPRP2), and carboxyl ester lipase (CEL), which may leak into the visceral fat or systemic circulation during pancreatitis. We, thus, aimed to determine the pancreatic lipase(s) regulating lipotoxicity during AP. For this AP, associated fat necrosis was analyzed using Western blot analysis. Bile acid (using liquid chromatography-tandem mass spectrometry) and fatty acid (using gas chromatography) concentrations were measured in human fat necrosis. The fat necrosis milieu was simulated in vitro using glyceryl trilinoleate because linoleic acid is increased in fat necrosis. Bile acid requirements to effectively hydrolyze glyceryl trilinoleate were studied using exogenous or overexpressed lipases. The renal cell line (HEK 293) was used to study lipotoxic injury. Because dual pancreatic lipase knockouts are lethal, exocrine parotid acini lacking lipases were used to verify the results. PNLIP, PNLIPRP2, and CEL were increased in fat necrosis. Although PNLIP and PNLIPRP2 were equipotent in inducing lipolysis and lipotoxic injury, CEL required bile acid concentrations higher than in human fat necrosis. The high bile acid requirements for effective lipolysis make CEL an unlikely mediator of lipotoxic injury in AP. It remains to be explored whether PNLIP or PNLIPRP2 worsens AP severity in vivo.

SUBMITTER: Khatua B

PROVIDER: S-EPMC6547060 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis.

Khatua Biswajit B Trivedi Ram N RN Noel Pawan P Patel Krutika K Singh Ravinder R de Oliveira Cristiane C Trivedi Shubham S Mishra Vivek V Lowe Mark M Singh Vijay P VP

The American journal of pathology 20190405 6

Acute lipolysis of visceral fat or circulating triglycerides may worsen acute pancreatitis (AP)-associated local and systemic injury. The pancreas expresses pancreatic triacylglycerol lipase (PNLIP), pancreatic lipase-related protein 2 (PNLIPRP2), and carboxyl ester lipase (CEL), which may leak into the visceral fat or systemic circulation during pancreatitis. We, thus, aimed to determine the pancreatic lipase(s) regulating lipotoxicity during AP. For this AP, associated fat necrosis was analyze ...[more]

PMID: 30954473

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Project description:Endocannabinoid 2-arachidonoylglycerol (2-AG) is an anti-nociceptive lipid that is inactivated through cellular uptake and subsequent catabolism by monoacylglycerol lipase (MAGL). In this study, we investigated the effects of MAGL inhibition on intestinal permeability and explored the possible mechanism. A rat model of severe acute pancreatitis (SAP) was established. Rats were divided into three groups according to treatment. We analyzed intestinal permeability to fluorescein isothiocyanate-dextran and the levels of inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and 2-AG. Hematoxylin and eosin staining was used to assess histological tissue changes. In vivo intestinal permeability was evaluated by transmission electron microscopy. We obtained ileum tissues, extracted total RNA, and applied RNA-sequencing. Sequencing data were analyzed by bioinformatics. Inflammatory factor levels were higher, while 2-AG levels were lower in the SAP group compared with the control group. Administration of JZL184 to rats with SAP increased the levels of 2-AG and lowered the levels of IL-6 and TNF-α. Notably, intestinal permeability was improved by JZL184 as demonstrated by fluorescein isothiocyanate-dextran measurement, hematoxylin and eosin staining, and transmission electron microscopy. RNA-sequencing showed significant transcriptional differences in SAP and JZL184 groups compared with the control group. KEGG analysis showed that the up- or downregulated genes in multiple comparison groups were enriched in two pathways, focal adhesion and PI3K-Akt signaling pathways. Differential alternative splicing (AS) genes, such as Myo9b, Lsp1, and Git2, have major functions in intestinal diseases. A total of 132 RNA-binding proteins (RBPs) were screened by crossing the identified abnormally expressed genes with the reported RBP genes. Among them, Hnrnpdl coexpressed the most AS events as the main RBP. MAGL inhibition improved intestinal mucosal barrier injury in SAP rats and induced a large number of differentially expressed genes and alternative splicing events. Hnrnpdl might play an important role in improving intestinal mucosal barrier injury by affecting alternative splicing events.

Project description:Elevation of blood triglycerides, primarily triglyceride-rich lipoproteins (TGRL), is an independent risk factor for cardiovascular disease and vascular dementia (VaD). Accumulating evidence indicates that both atherosclerosis and VaD are linked to vascular inflammation. However, the role of TGRL in vascular inflammation, which increases risk for VaD, remains largely unknown and its underlying mechanisms are still unclear. We strived to determine the effects of postprandial TGRL exposure on brain microvascular endothelial cells, the potential risk factor of vascular inflammation, resulting in VaD. We showed in Aung et al., J Lipid Res., 2016 that postprandial TGRL lipolysis products (TL) activate mitochondrial reactive oxygen species (ROS) and increase the expression of the stress-responsive protein, activating transcription factor 3 (ATF3), which injures human brain microvascular endothelial cells (HBMECs) in vitro. In this study, we deployed high-throughput sequencing (HTS)-based RNA sequencing methods and mito stress and glycolytic rate assays with an Agilent Seahorse XF analyzer and profiled the differential expression of transcripts, constructed signaling pathways, and measured mitochondrial respiration, ATP production, proton leak, and glycolysis of HBMECs treated with TL. Conclusions: TL potentiate ROS by mitochondria which activate mitochondrial oxidative stress, decrease ATP production, increase mitochondrial proton leak and glycolysis rate, and mitochondria DNA damage. Additionally, CPT1A1 siRNA knockdown suppresses oxidative stress and prevents mitochondrial dysfunction and vascular inflammation in TL treated HBMECs. TL activates ATF3-MAPKinase, TNF, and NRF2 signaling pathways. Furthermore, the NRF2 signaling pathway which is upstream of the ATF3-MAPKinase signaling pathway, is also regulated by the mitochondrial oxidative stress. We are the first to report differential inflammatory characteristics of transcript variants 4 (ATF3-T4) and 5 (ATF3-T5) of the stress responsive gene ATF3 in HBMECs induced by postprandial TL. Specifically, our data indicates that ATF3-T4 predominantly regulates the TL-induced brain microvascular inflammation and TNF signaling. Both siRNAs of ATF3-T4 and ATF3-T5 suppress cells apoptosis and lipotoxic brain microvascular endothelial cells. These novel signaling pathways triggered by oxidative stress-responsive transcript variants, ATF3-T4 and ATF3-T5, in the brain microvascular inflammation induced by TGRL lipolysis products may contribute to pathophysiological processes of vascular dementia.

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Dataset Information

Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis.

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Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis.

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