<p>Silica exposure precipitates irreversible lung injury; however, its long-term neurological sequelae—and the microglial mechanisms underlying these effects—remain poorly understood. Here, we demonstrate that inhaled crystalline silica induces persistent hippocampal inflammation, anxiety- and depression-like behaviors, and neuronal loss in mice. Bulk RNA sequencing, immunophenotyping, and pharmacological depletion studies revealed that microglia are the primary source of complement C1q in silica-exposed brains. Mechanistically, silica-induced lipocalin-2 (LCN2) engages the melanocortin-4 receptor (MC4R) on microglia, activating a cAMP/PKA/NF-κB cascade that transcriptionally upregulates C1q. Pharmacological blockade of MC4R (using PF) abolished C1q overproduction, normalized brain-derived neurotrophic factor levels, and restored both synaptic integrity and behavioral performance. Our findings establish the LCN2–MC4R–C1q axis as a critical microglial pathway in silica-related neurotoxicity and identify MC4R antagonism as a promising, readily translatable intervention for occupational neuroinflammation.</p>

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A microglial LCN2-MC4R signaling axis drives silica-induced neuronal damage via C1q release

  • Xia Li,
  • Zihao Xie,
  • Hangbing Cao,
  • Fei Wang,
  • Ruiqing Yan,
  • Jianxin Wang,
  • Chao Liu,
  • Jialing Wang,
  • Min Mu,
  • Yan Liu,
  • ShanShan Ling,
  • Huiyu Ye,
  • Xinrong Tao

摘要

Silica exposure precipitates irreversible lung injury; however, its long-term neurological sequelae—and the microglial mechanisms underlying these effects—remain poorly understood. Here, we demonstrate that inhaled crystalline silica induces persistent hippocampal inflammation, anxiety- and depression-like behaviors, and neuronal loss in mice. Bulk RNA sequencing, immunophenotyping, and pharmacological depletion studies revealed that microglia are the primary source of complement C1q in silica-exposed brains. Mechanistically, silica-induced lipocalin-2 (LCN2) engages the melanocortin-4 receptor (MC4R) on microglia, activating a cAMP/PKA/NF-κB cascade that transcriptionally upregulates C1q. Pharmacological blockade of MC4R (using PF) abolished C1q overproduction, normalized brain-derived neurotrophic factor levels, and restored both synaptic integrity and behavioral performance. Our findings establish the LCN2–MC4R–C1q axis as a critical microglial pathway in silica-related neurotoxicity and identify MC4R antagonism as a promising, readily translatable intervention for occupational neuroinflammation.