Scholarlink

<p>Microglia-neuron contacts have been shown to regulate neural network activity through the formation and elimination of synapses. The pathogenesis of major depressive disorder is accompanied by a decline in brain-derived neurotrophic factor (BDNF) signaling, associated with increased microglia activity that disrupts cognitive function. The actions of both typical and rapid-acting antidepressant drugs, which have been shown to increase BDNF signaling through the tropomyosin receptor kinase B (TrkB) receptor, decrease microglia activation and the levels of pro-inflammatory cytokines. Examining the link between BDNF signaling and the microglial pro-inflammatory response, we demonstrate that TrkB signaling elicits the neuronal secretion of CD22 (Siglec-2), a sialic acid-binding immunoglobulin-type lectin, to inhibit microglial activation and alleviate depression-like symptoms. In a male chronic mild stress (CMS) mouse model of depression decreased expression of the postsynaptic scaffolding protein PSD-95 and Gαi1/3 were found to compromise TrkB signaling leading to reduced CD22 levels in hippocampal tissue. Restoration of TrkB-Gαi1/3-Akt signaling with dSyn3, a peptidomimetic compound targeting the PDZ3 domain of PSD-95, enhanced CD22 expression to inhibit microglial activation, promote dendritic spine formation and rapidly mitigate depression-like symptoms. Furthermore, hippocampal overexpression of CD22 in neurons was sufficient to reduce microglial activation and depressive-like behaviors in male CMS mice. S-ketamine, a rapid-acting antidepressant, increased CD22 expression to mitigate depression-like symptoms. While neuronal knockdown of CD22 in the hippocampus did not significantly impair the rapid (within 4 h) antidepressant effects typically observed with S-ketamine or dSyn3 administration, strikingly, knockdown of CD22 attenuated the long-acting (within 3 days) antidepressant effects of S-ketamine or dSyn3, as evidenced by sustained immobility in the TST (tail suspension test) and FST (forced swim test), and a lack of improvement in sucrose preference. In contrast, a single dose of fluoxetine failed to increase CD22 expression or inhibit microglia activity. These results suggest that rapidly-acting anti-depressant drugs enhance TrkB-induced neuronal expression and secretion of CD22 to promote the homeostatic state of microglia required for antidepressant actions.</p><p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

TrkB promotes the neuronal secretion of soluble Siglec-2 (CD22) to mitigate microglial activation and alleviate depression-like behaviors in male mice

  • 期刊论文

  • 发表日期：

    2026年4月1日

查看全文
  • Xin Shi,
  • Shi-zhong Cai,
  • Jin-long Chai,
  • Chen-yang Xu,
  • Bo-ya Zhou,
  • Han-qi Liu,
  • John Marshall,
  • Cong Cao

摘要

Microglia-neuron contacts have been shown to regulate neural network activity through the formation and elimination of synapses. The pathogenesis of major depressive disorder is accompanied by a decline in brain-derived neurotrophic factor (BDNF) signaling, associated with increased microglia activity that disrupts cognitive function. The actions of both typical and rapid-acting antidepressant drugs, which have been shown to increase BDNF signaling through the tropomyosin receptor kinase B (TrkB) receptor, decrease microglia activation and the levels of pro-inflammatory cytokines. Examining the link between BDNF signaling and the microglial pro-inflammatory response, we demonstrate that TrkB signaling elicits the neuronal secretion of CD22 (Siglec-2), a sialic acid-binding immunoglobulin-type lectin, to inhibit microglial activation and alleviate depression-like symptoms. In a male chronic mild stress (CMS) mouse model of depression decreased expression of the postsynaptic scaffolding protein PSD-95 and Gαi1/3 were found to compromise TrkB signaling leading to reduced CD22 levels in hippocampal tissue. Restoration of TrkB-Gαi1/3-Akt signaling with dSyn3, a peptidomimetic compound targeting the PDZ3 domain of PSD-95, enhanced CD22 expression to inhibit microglial activation, promote dendritic spine formation and rapidly mitigate depression-like symptoms. Furthermore, hippocampal overexpression of CD22 in neurons was sufficient to reduce microglial activation and depressive-like behaviors in male CMS mice. S-ketamine, a rapid-acting antidepressant, increased CD22 expression to mitigate depression-like symptoms. While neuronal knockdown of CD22 in the hippocampus did not significantly impair the rapid (within 4 h) antidepressant effects typically observed with S-ketamine or dSyn3 administration, strikingly, knockdown of CD22 attenuated the long-acting (within 3 days) antidepressant effects of S-ketamine or dSyn3, as evidenced by sustained immobility in the TST (tail suspension test) and FST (forced swim test), and a lack of improvement in sucrose preference. In contrast, a single dose of fluoxetine failed to increase CD22 expression or inhibit microglia activity. These results suggest that rapidly-acting anti-depressant drugs enhance TrkB-induced neuronal expression and secretion of CD22 to promote the homeostatic state of microglia required for antidepressant actions.