Rationale: TRPM2 (transient receptor potential melastatin-2) expressed in endothelial cells (ECs) is a cation channel mediating Ca²⁺ entry in response to intracellular generation of adenosine diphosphoribose—the TRPM2 ligand.

Objective: Because polymorphonuclear neutrophils (PMN) interaction with ECs generates reactive oxygen species, we addressed the possible role of TRPM2 expressed in ECs in the mechanism of transendothelial migration of PMNs.

Methods and Results: We observed defective PMN transmigration in response to lipopolysaccharide challenge in adult mice in which the EC expressed TRPM2 is conditionally deleted (Trpm2^iΔEC). PMN interaction with ECs induced the entry of Ca²⁺ in ECs via the EC-expressed TRPM2. Prevention of generation of adenosine diphosphoribose in ECs significantly reduced Ca²⁺ entry in response to PMN activation of TRPM2 in ECs. PMNs isolated from gp91phox^−/− mice significantly reduced Ca²⁺ entry in ECs via TRPM2 as compared with wild-type PMNs and failed to induce PMN transmigration. Overexpression of the adenosine diphosphoribose insensitive TRPM2 mutant channel (C1008→A) in ECs suppressed the Ca²⁺ entry response. Further, the forced expression of TRPM2 mutant channel (C1008→A) or silencing of poly ADP-ribose polymerase in ECs of mice prevented PMN transmigration.

Conclusions: Thus, endotoxin-induced transmigration of PMNs was secondary to TRPM2-activated Ca²⁺ signaling and VE-cadherin phosphorylation resulting in the disassembly of adherens junctions and opening of the paracellular pathways. These results suggest blocking TRPM2 activation in ECs is a potentially important means of therapeutically modifying PMN-mediated vascular inflammation.

中文翻译：

---

内皮细胞表达TRPM2的嗜中性粒细胞激活介导跨内皮嗜中性粒细胞迁移和血管损伤的新颖性和意义。

原理：内皮细胞（ECs）中表达的TRPM2（瞬时受体电位melastatin-2）是介导Ca ²⁺进入的阳离子通道，响应于腺苷二磷酸核糖（TRPM2配体）的细胞内生成。

目的：由于多形核中性粒细胞（PMN）与EC的相互作用产生了活性氧，因此我们探讨了EC中表达的TRPM2在PMN跨内皮迁移机制中的可能作用。

方法和结果：我们观察到成年小鼠中脂多糖激发后PMN转运^缺陷，其中EC表达的TRPM2被有条件地删除（ ^Trpm2iΔEC）。PMN与EC的相互作用通过EC表达的TRPM2诱导Ca ²⁺进入EC。响应于EC中TRPM2的PMN激活，阻止EC中产生腺苷二磷酸核糖可显着减少Ca ^2+的进入。从gp91phox ^-/-小鼠中分离出的PMN显着降低了Ca ²⁺与野生型PMN相比，它们通过TRPM2进入EC并未能诱导PMN迁移。EC中腺苷二磷酸核糖不敏感的TRPM2突变体通道（C1008→A）的过表达抑制了Ca ²⁺进入反应。此外，在小鼠EC中强迫表达TRPM2突变体通道（C1008→A）或使聚ADP-核糖聚合酶沉默可防止PMN迁移。

结论：因此，内毒素诱导的PMN迁移是TRPM2激活的Ca ²⁺信号传导和VE-钙黏着蛋白磷酸化的继发，导致粘附连接的解体和旁细胞途径的开放。这些结果表明，阻断EC中TRPM2的激活是治疗上修饰PMN介导的血管炎症的潜在重要手段。