PLA2G2E Human

What is human PLA2G2E and what is its genomic location?

PLA2G2E (phospholipase A2 group IIE) is a member of the secreted phospholipase A2 (sPLA2) family that catalyzes the hydrolysis of glycerophospholipids, releasing fatty acids and lysophospholipids. This enzyme plays a significant role in lipid metabolism and immune regulation, particularly in the context of respiratory viral infections .

The human PLA2G2E gene is located on Chromosome 1, specifically on the reference sequence NC_000001.11 in the GRCh38.p14 Primary Assembly . The gene is part of the group II subfamily within the broader sPLA2 family, characterized by specific structural motifs involved in calcium binding and catalytic activity .

What is the expression pattern of PLA2G2E in human tissues?

Under normal physiological conditions, PLA2G2E exhibits relatively low expression levels in most tissues. It is primarily localized to glutamate-rich tissues and maintains minimal expression under homeostatic conditions .

• Viral infection: H1N1 influenza virus infection induces marked upregulation of PLA2G2E expression in human lung cancer cell lines (A549 and NCI-H1299)

• Cell-specific expression: During influenza infection, PLA2G2E expression increases predominantly in lung epithelial cells rather than alveolar macrophages or endothelial cells

• Inflammatory stimuli: Alveolar macrophages show upregulated PLA2G2E expression in response to lipopolysaccharide (LPS) stimulation, highlighting its role in immune activation

This differential expression pattern suggests PLA2G2E plays a context-dependent role in inflammatory and immune responses, with specific regulation depending on cellular environment and stimulation conditions.

How does PLA2G2E function differ from other phospholipase A2 family members?

While the search results don't provide comprehensive comparative data on all PLA2 family members, we can extract some distinguishing characteristics of PLA2G2E:

PLA2G2E appears to have a specialized role in modulating T cell responses during viral infections, particularly influenza, distinguishing it from other phospholipases that may have broader or different immune regulatory functions .

What experimental methods are recommended for measuring PLA2G2E expression?

Based on methodologies described in the research literature, the following approaches are recommended for measuring PLA2G2E expression:

• Transcriptomic Analysis:

  • Real-time PCR for targeted gene expression analysis

  • RNA sequencing for comprehensive expression profiling in response to stimuli

  • Reanalysis of publicly available transcriptomic datasets to examine PLA2G2E expression patterns

• Cell-Specific Expression Analysis:

  • Cell sorting followed by gene expression analysis to determine which cell types express PLA2G2E

  • Single-cell RNA sequencing to examine heterogeneity in expression across cell populations

• Protein Detection:

  • Western blotting using specific antibodies against PLA2G2E

  • Immunohistochemistry for tissue localization studies

When designing experiments to measure PLA2G2E expression, researchers should consider:

• Including appropriate positive controls (e.g., influenza-infected lung epithelial cells)

• Examining multiple timepoints post-stimulation to capture expression dynamics

• Analyzing both mRNA and protein levels to account for post-transcriptional regulation

How does PLA2G2E deficiency affect susceptibility to viral infections?

Research using PLA2G2E-deficient mouse models (Pla2g2e-/-) demonstrates significant impacts on viral susceptibility and immune responses :

Interestingly, Pla2g2e-/- mice displayed comparable pulmonary pathological changes to wild-type mice, with similar wall thickening and inflammatory cell infiltration on days 7 and 14 post-infection. Both groups showed occasional hemorrhage and pulmonary edema .

The expression levels of chemokines (CCL2, CCL3, CCL5, CXCL2, CXCL5, and CXCL10) and proinflammatory cytokines (IL-1β, IL-6, and IL-8) were upregulated in lung tissues of both wild-type and Pla2g2e-/- mice at comparable levels, suggesting that PLA2G2E's protective effect against viral infection operates through mechanisms distinct from general inflammatory pathways .

What is the relationship between PLA2G2E and T cell-mediated immunity during influenza infection?

PLA2G2E plays a critical role in regulating T cell-mediated immunity during influenza virus infection through several mechanisms :

• T Cell Activation and Function:

  • Pla2g2e-/- mice show impaired influenza-specific cellular immunity

  • T cell-mediated cytotoxicity is reduced in PLA2G2E-deficient animals

  • The frequency of virus-specific CD8+ T cells (D^bNP 366-374+CD8+) in broncho-alveolar lavage fluid (BALF) is decreased in Pla2g2e-/- mice

  • Interestingly, I-A^bNP 311-325+CD4+ T cells are increased in Pla2g2e-/- mice, suggesting differential regulation of CD4+ and CD8+ T cell responses

• Cytokine Production:

  • IFN-γ production is significantly reduced in both BALF and splenic T cells from Pla2g2e-/- mice upon stimulation with viral antigens

  • The frequencies of IFN-γ+CD4+ and IFN-γ+CD8+ T cells are significantly lower in Pla2g2e-/- mice compared to wild-type

• Humoral vs. Cellular Immunity:

  • While Pla2g2e-/- mice show impaired T cell responses, they maintain comparable innate and humoral immune responses to influenza virus

  • This selective effect on T cell-mediated immunity highlights PLA2G2E's specialized role in adaptive immune regulation

These findings demonstrate that PLA2G2E contributes specifically to the regulation of T cell responses during influenza virus infection, with minimal impact on other aspects of antiviral immunity.

How do transgenic models expressing human PLA2G2E respond to viral challenge?

Transgenic mice expressing the human PLA2G2E gene (hPLA2G2E mice) at the Rosa26 genomic safe harbor site demonstrate enhanced antiviral responses compared to wild-type controls :

The significant improvement in survival and reduced weight loss in hPLA2G2E transgenic mice strongly suggests that human PLA2G2E provides protective effects during influenza infection . This enhanced protection correlates with increased virus-specific CD8+ T cells, further supporting PLA2G2E's role in modulating T cell-mediated immunity.

These findings have important implications for developing potential therapeutic strategies targeting PLA2G2E enhancement to combat influenza and potentially other viral infections.

What lipid mediator alterations occur with PLA2G2E deficiency?

Pla2g2e deficiency results in perturbation of lipid mediators in both lung tissue and T cells, which likely contributes to the observed impacts on immune responses . As a phospholipase, PLA2G2E catalyzes the release of fatty acids from membrane phospholipids, potentially affecting the production of various bioactive lipid mediators.

While the search results don't provide detailed lipidomic analysis data, we can infer that PLA2G2E deficiency likely affects:

• Eicosanoid Production: Altered release of arachidonic acid would impact the synthesis of prostaglandins, leukotrienes, and other eicosanoids involved in inflammation and immune regulation

• Specialized Pro-resolving Mediators (SPMs): Changes in omega-3 fatty acid release could affect the production of resolvins, protectins, and maresins that regulate inflammation resolution

• Lysophospholipids: As products of phospholipase A2 activity, altered levels of lysophospholipids may affect membrane properties and signaling pathways in immune cells

The perturbation of these lipid mediators in T cells specifically suggests a mechanism by which PLA2G2E deficiency leads to impaired T cell activation, proliferation, and effector functions during viral infection .

What methodological approaches should be considered for studying PLA2G2E in therapeutic development?

Based on current research findings, several methodological approaches would be valuable for investigating PLA2G2E as a therapeutic target :

• Animal Models:

  • Utilize both knockout (Pla2g2e-/-) and transgenic (hPLA2G2E) mouse models to assess loss- and gain-of-function effects

  • Consider humanized mouse models expressing human immune system components to better predict translational outcomes

  • Employ various viral challenge models beyond influenza to determine breadth of protective effects

• Cell-Based Assays:

  • Primary T cell isolation and functional assays (proliferation, cytotoxicity, cytokine production)

  • Ex vivo stimulation of patient-derived T cells with recombinant PLA2G2E

  • Co-culture systems to examine interactions between PLA2G2E-producing epithelial cells and T cells

• Therapeutic Delivery Strategies:

  • Gene therapy approaches targeting PLA2G2E expression

  • Recombinant PLA2G2E protein administration via appropriate delivery systems

  • Small molecule modulators of PLA2G2E expression or activity

• Biomarker Development:

  • Lipidomic profiling to identify specific lipid mediator signatures associated with PLA2G2E activity

  • T cell functional assays as pharmacodynamic markers of PLA2G2E modulation

  • Viral load quantification as an efficacy endpoint

• Safety Assessment:

  • Comprehensive evaluation of potential off-target effects, particularly on inflammatory pathways

  • Dose-ranging studies to determine therapeutic window

  • Long-term consequences of PLA2G2E modulation on immune homeostasis

This multi-faceted approach would provide valuable insights into PLA2G2E's potential as a therapeutic target for viral infections and possibly other conditions involving T cell dysfunction.

What challenges exist in translating PLA2G2E research to human clinical applications?

Several significant challenges must be addressed when translating PLA2G2E research findings from animal models to human applications:

• Species-Specific Differences:

  • Human and mouse PLA2G2E may differ in substrate specificity, regulation, or downstream effects

  • The immune environment in which PLA2G2E functions may vary between species

  • Transgenic models expressing human PLA2G2E in mice provide valuable insights but cannot fully recapitulate the human context

• Target Cell Identification and Accessibility:

  • Determining which human cell populations should be targeted to enhance PLA2G2E expression

  • Developing delivery methods that can effectively reach these target cells

  • Understanding tissue-specific regulation of PLA2G2E in humans

• Therapeutic Timing:

  • Identifying the optimal intervention window during infection or disease progression

  • Determining duration of treatment needed for efficacy

  • Assessing potential for prophylactic versus therapeutic applications

• Individual Variability:

  • Genetic polymorphisms in human PLA2G2E may affect function or therapeutic response

  • Existing immune status and comorbidities could influence treatment outcomes

  • Potential interactions with concurrent medications or treatments

How can researchers effectively measure T cell responses influenced by PLA2G2E in experimental settings?

To accurately assess PLA2G2E's influence on T cell responses, researchers should consider these methodological approaches :

• Antigen-Specific T Cell Quantification:

  • MHC tetramer staining for virus-specific CD8+ T cells (e.g., D^bNP 366-374+CD8+ T cells for influenza)

  • MHC class II tetramer staining for virus-specific CD4+ T cells (e.g., I-A^bNP 311-325+CD4+)

  • Flow cytometric analysis to determine frequency and phenotype of antigen-specific cells

• Functional T Cell Assays:

  • Enzyme-linked immunospot (ELISpot) assay to measure IFN-γ production upon antigen stimulation

  • Intracellular cytokine staining to determine frequencies of cytokine-producing T cells

  • Cytotoxicity assays to assess killing capacity of CD8+ T cells

• T Cell Activation and Differentiation:

  • Analysis of activation markers (CD25, CD69, etc.)

  • Assessment of memory T cell development (central memory vs. effector memory)

  • Evaluation of exhaustion markers in chronic stimulation settings

• In vivo Approaches:

  • Adoptive transfer of labeled, antigen-specific T cells to track proliferation and migration

  • In vivo killing assays to assess cytotoxic function

  • Two-photon microscopy to visualize T cell interactions in tissues

When designing experiments, researchers should consider using multiple complementary assays and incorporate appropriate controls, including both positive controls (wild-type mice) and negative controls (Pla2g2e-/- mice) .

What methodological considerations are important when studying PLA2G2E's role in lipid mediator production?

To effectively study PLA2G2E's influence on lipid mediator profiles, researchers should consider these methodological approaches:

• Comprehensive Lipidomic Analysis:

  • Liquid chromatography-mass spectrometry (LC-MS) for detailed lipid profiling

  • Targeted analysis of eicosanoids, specialized pro-resolving mediators, and lysophospholipids

  • Spatial lipidomics to determine tissue-specific lipid alterations

• Enzymatic Activity Assays:

  • Fluorogenic substrate assays to measure PLA2G2E enzymatic activity

  • Competition assays with other phospholipases to determine substrate specificity

  • In vitro reconstitution with defined phospholipid substrates

• Cellular Models:

  • Comparison of lipid profiles between wild-type, Pla2g2e-/-, and hPLA2G2E transgenic models

  • Cell-specific analysis (epithelial cells, T cells, macrophages) to determine cell-type-dependent effects

  • Stimulation conditions that mimic viral infection or inflammatory environments

• Time-Course Analysis:

  • Kinetic studies to track changes in lipid mediators over time following stimulation

  • Correlation with T cell activation states and functional outcomes

  • Assessment of lipid mediator persistence and metabolism

Research indicates that PLA2G2E deficiency results in perturbation of lipid mediators in both lung tissue and T cells, potentially contributing to impaired T cell responses during viral infection . Detailed characterization of these lipid alterations would provide valuable insights into the mechanisms by which PLA2G2E influences immune function.

What are promising experimental models for PLA2G2E research beyond influenza infection?

While current research has focused on PLA2G2E's role in influenza virus infection, several experimental models could expand our understanding of its broader biological functions:

• Additional Viral Infection Models:

  • Respiratory viruses beyond influenza (RSV, SARS-CoV-2, parainfluenza viruses)

  • Systemic viral infections to assess non-respiratory roles

  • Persistent viral infections to examine chronic immune regulation

• Autoimmune Disease Models:

  • Experimental autoimmune encephalomyelitis (EAE) for multiple sclerosis

  • Collagen-induced arthritis

  • Type 1 diabetes models

  • These models would help determine whether PLA2G2E plays a protective or pathogenic role in aberrant T cell responses

• Cancer Immunotherapy Models:

  • Tumor challenge models to assess impact on anti-tumor immunity

  • Checkpoint inhibitor combination studies

  • Adoptive T cell therapy models with PLA2G2E-modified T cells

• Tissue-Specific Conditional Models:

  • Cell-specific PLA2G2E deletion or overexpression using Cre-lox systems

  • Inducible expression systems to control timing of PLA2G2E modulation

  • Tissue-specific expression to determine local versus systemic effects

These diverse experimental approaches would provide a more comprehensive understanding of PLA2G2E's role in immune regulation beyond respiratory viral infections.

How might PLA2G2E be integrated into broader immune therapeutic strategies?

Based on its role in T cell regulation, PLA2G2E could be integrated into therapeutic strategies in several innovative ways:

• Combination with Existing Antivirals:

  • PLA2G2E enhancement could complement direct-acting antivirals by strengthening T cell-mediated viral clearance

  • Potential for reduced viral resistance through multi-mechanism approach

  • Enhanced resolution of infection through improved T cell function

• Vaccine Adjuvant Development:

  • PLA2G2E modulators could potentially enhance T cell responses to vaccination

  • Particularly valuable for vaccines requiring strong cellular immunity

  • Could improve protection in populations with suboptimal vaccine responses

• Cell-Based Immunotherapies:

  • Engineering T cells to express or respond to PLA2G2E for adoptive cell therapies

  • Modulation of lipid mediator environment to enhance CAR-T cell function

  • Ex vivo expansion protocols incorporating PLA2G2E stimulation

• Precision Medicine Applications:

  • Genetic screening for PLA2G2E variants that impact susceptibility to viral infections

  • Tailored therapeutic approaches based on individual PLA2G2E expression or activity

  • Biomarker development to identify patients most likely to benefit from PLA2G2E-targeted therapies

Research with transgenic mice expressing human PLA2G2E demonstrates significant protection against influenza virus infection, suggesting that enhancing PLA2G2E expression or activity could be a viable therapeutic strategy for managing viral infections .

What consensus exists regarding the importance of PLA2G2E in human immunology?

Current research provides compelling evidence for PLA2G2E's significant role in T cell-mediated immunity, particularly during viral infections. The findings from both knockout and transgenic models consistently demonstrate that PLA2G2E:

• Contributes to protection against influenza virus infection through regulation of T cell responses

• Specifically modulates T cell-mediated immunity without significantly affecting innate or humoral immune responses

• Influences lipid mediator profiles in lung tissue and T cells, likely affecting immune cell function

• When overexpressed (human PLA2G2E in transgenic mice), provides enhanced protection against viral challenge

These consistent findings across multiple experimental approaches establish PLA2G2E as an important regulator of T cell-mediated immunity with potential therapeutic implications. The selective effect on T cell responses, rather than broad immunomodulation, suggests PLA2G2E could be targeted with potentially fewer off-target effects than general immunomodulatory approaches.

The research also highlights the interconnection between lipid metabolism and immune function, with PLA2G2E serving as a critical link between these physiological systems. This emerging understanding opens new avenues for immunomodulatory strategies that target specific aspects of lipid metabolism to enhance desired immune responses.