199: PLD4 Deficiency and Lupus: When Nuclease Failure Ignites Autoimmunity

PLD4 Deficiency and Lupus: When Nuclease Failure Ignites Autoimmunity

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License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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Episode link: https://basebybase.com/episodes/pld4-deficiency-and-lupus-when-nuclease-failure-ignites-autoimmunity

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-11-15.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the core scientific narrative from mutation discovery to mechanistic function, single-cell analyses, mouse model phenotypes, and therapeutic implications.
- transcript topics: PLD4 mutations and monogenic lupus; Endosomal nucleic acid sensing and TLR7/9 signaling; PLD4 exonuclease activity assays; scRNA-seq of patient PBMCs and IFN signatures; CyTOF cytokine profiling in PBMCs; Pld4−/− mice autoimmunity and nephritis

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- Five SLE patients with biallelic PLD4 mutations were identified.
- PLD4 functions as a 5′ exonuclease that cleaves ssDNA and ssRNA in endosomes to limit TLR7/9 signaling.
- Mutations in PLD4 impair exonuclease activity in vitro (loss of catalytic function observed for patient-derived variants).
- scRNA-seq and CyTOF show IFN/TLR pathway activation predominantly in dendritic cells and monocytes.
- Pld4−/− mice display autoimmunity and nephritis with expansion of plasmacytoid dendritic cells (pDCs) and plasma cells.
- Baricitinib (a JAK inhibitor) reduces type I IFN signaling and rescues phenotypes in PLD4-deficient models (mice and patient-derived cells).

QC result: Pass.