Ou Ziwei, Dolmatova Elena, Mandavilli Rohan, Qu Hongyan, Gafford Georgette, White Taylor, Valdivia Alejandra, Lassègue Bernard, Hernandes Marina S, Griendling Kathy K
Division of Cardiology Department of Medicine Emory University Atlanta GA.
Department of Cardiovascular Medicine Xiangya HospitalCentral South University Changsha China.
J Am Heart Assoc. 2022 May 17;11(10):e025181. doi: 10.1161/JAHA.121.025181. Epub 2022 May 10.
Background Lung injury, a severe adverse outcome of lipopolysaccharide-induced acute respiratory distress syndrome, is attributed to excessive neutrophil recruitment and effector response. Poldip2 (polymerase δ-interacting protein 2) plays a critical role in regulating endothelial permeability and leukocyte recruitment in acute inflammation. Thus, we hypothesized that Poldip2 is involved in neutrophil recruitment to inflamed lungs. Methods and Results After characterizing myeloid-specific knockout mice, we showed that at 18 hours post-lipopolysaccharide injection, bronchoalveolar lavage from myeloid Poldip2-deficient mice contained fewer inflammatory cells (8 [4-16] versus 29 [12-57]×10/mL in wild-type mice) and a smaller percentage of neutrophils (30% [28%-34%] versus 38% [33%-41%] in wild-type mice), while the main chemoattractants for neutrophils remained unaffected. In vitro, Poldip2-deficient neutrophils responded as well as wild-type neutrophils to inflammatory stimuli with respect to neutrophil extracellular trap formation, reactive oxygen species production, and induction of cytokines. However, neutrophil adherence to a tumor necrosis factor-α stimulated endothelial monolayer was inhibited by Poldip2 depletion (225 [115-272] wild-type [myePoldip2] versus 133 [62-178] myeloid-specific knockout [myePoldip2] neutrophils) as was transmigration (1.7 [1.3-2.1] versus 1.1 [1.0-1.4] relative to baseline transmigration). To determine the underlying mechanism, we examined the surface expression of β2-integrin, its binding to soluble intercellular adhesion molecule 1, and Pyk2 phosphorylation. Surface expression of β2-integrins was not affected by Poldip2 deletion, whereas β2-integrins and Pyk2 were less activated in Poldip2-deficient neutrophils. Conclusions These results suggest that myeloid Poldip2 is involved in β2-integrin activation during the inflammatory response, which in turn mediates neutrophil-to-endothelium adhesion in lipopolysaccharide-induced acute respiratory distress syndrome.
肺损伤是脂多糖诱导的急性呼吸窘迫综合征的严重不良后果，归因于中性粒细胞过度募集和效应反应。Poldip2（聚合酶δ相互作用蛋白2）在急性炎症中调节内皮通透性和白细胞募集中起关键作用。因此，我们推测Poldip2参与中性粒细胞向炎症肺组织的募集。
在对髓系特异性敲除小鼠进行特征分析后，我们发现脂多糖注射后18小时，髓系Poldip2缺陷小鼠的支气管肺泡灌洗液中炎症细胞较少（野生型小鼠为29[12 - 57]×10/mL，髓系Poldip2缺陷小鼠为8[4 - 16]×10/mL），中性粒细胞百分比也较小（野生型小鼠为38%[33% - 41%]，髓系Poldip2缺陷小鼠为30%[28% - 34%]），而中性粒细胞的主要趋化因子未受影响。在体外，就中性粒细胞胞外陷阱形成、活性氧产生和细胞因子诱导而言，Poldip2缺陷的中性粒细胞对炎症刺激的反应与野生型中性粒细胞相同。然而，Poldip2缺失会抑制中性粒细胞对肿瘤坏死因子-α刺激的内皮单层的黏附（野生型[myePoldip2]中性粒细胞为225[115 - 272]，髓系特异性敲除[myePoldip2]中性粒细胞为133[62 - 178]）以及迁移（相对于基线迁移，野生型为1.7[1.3 - 2.1]，髓系特异性敲除为1.1[1.0 - 1.4]）。为确定潜在机制，我们检测了β2整合素的表面表达、其与可溶性细胞间黏附分子1的结合以及Pyk2磷酸化。β2整合素的表面表达不受Poldip2缺失的影响，而在Poldip2缺陷的中性粒细胞中，β2整合素和Pyk2的激活程度较低。
这些结果表明，髓系Poldip2在炎症反应中参与β2整合素的激活，进而介导脂多糖诱导的急性呼吸窘迫综合征中中性粒细胞与内皮细胞的黏附。
