Pharmacology and Experimental Therapeutics Unit, School of Pharmacy, Institute for Drug Research, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
Pulmonary and Critical Care Medicine, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Int Arch Allergy Immunol. 2023;184(7):720-726. doi: 10.1159/000529606. Epub 2023 Mar 16.
CD300a is an inhibitory receptor (IR) expressed on several leukocytes, including mast cells (MCs) and macrophages (MΦ), important cells in allergic inflammation (AI). We have previously characterized CD300a role on MCs and in vivo in mouse models of allergy, in which the absence of CD300a resulted in increased inflammatory features and delayed resolution. However, the exact mechanism of this delayed resolution is unclear. Our hypothesis is that MΦ, important players in resolution, might be impaired when CD300a is absent.
The aim of the study was to investigate CD300a-dependent functionality of mouse MΦ.
MΦ were purified from the peritoneum of wild-type (WT) and CD300a-/- mice naïve and 48 h and 96 h after challenge with ovalbumin/alum. Phenotype switching was analyzed via specific M1-M2 inducers and markers. MΦ phagocytotic ability was assessed via Staphylococcus aureus pHrodo-conjugated bioparticles. The influence of MCs on MΦ was investigated by incubating WT MΦ with supernatants from non-activated and IgE-activated bone marrow-derived MCs (BMMCs) and analyzing functional responses.
Naïve CD300a-/- MΦ presented with increased sensitivity to activation when treated with LPS. Absence of CD300a results in increased Arg1 expression and increased IL-6 release when MΦ are purified from allergic peritonitis-induced mice. Similar results were obtained when CD300a-/- MΦ were purified 96 h after challenge. On the other hand, CD300a absence did not affect phagocytosis. WT MΦ incubated with supernatants of non-activated and IgE-activated BMMCs presented with increased iNOS expression and decreased Arg1 levels.
The IR CD300a controls the activation state of MΦ, and its absence could augment the inflammatory state seen in CD300a-/- mice. Moreover, MCs can also influence MΦ phenotype switching. This may partially explain the delayed AI resolution seen in these mice.
CD300a 是一种抑制性受体 (IR)，表达于几种白细胞上，包括肥大细胞 (MCs) 和巨噬细胞 (MΦ)，它们是过敏炎症 (AI) 中的重要细胞。我们之前已经描述了 CD300a 在 MCs 上的作用，以及在过敏的小鼠模型中的体内作用，其中 CD300a 的缺失导致炎症特征增加和缓解延迟。然而，这种缓解延迟的确切机制尚不清楚。我们的假设是，在 CD300a 缺失的情况下，作为缓解重要参与者的 MΦ 可能会受损。
本研究旨在研究依赖 CD300a 的小鼠 MΦ 的功能。
从野生型 (WT) 和 CD300a-/- 小鼠的腹膜中纯化 MΦ，分别在卵白蛋白/明矾挑战后的 48 小时和 96 小时进行分析。通过特异性 M1-M2 诱导剂和标志物分析表型转换。通过金黄色葡萄球菌 pHrodo 结合的生物颗粒评估 MΦ 的吞噬能力。通过孵育 WT MΦ与非激活和 IgE 激活的骨髓来源的 MCs (BMMCs) 的上清液，并分析功能反应，研究 MCs 对 MΦ 的影响。
在 LPS 处理时，幼稚型 CD300a-/- MΦ 表现出对激活的敏感性增加。当从过敏腹膜炎诱导的小鼠中纯化 MΦ 时，CD300a 的缺失导致 Arg1 表达增加和 IL-6 释放增加。在挑战后 96 小时纯化 CD300a-/- MΦ 时也得到了类似的结果。另一方面，CD300a 的缺失并不影响吞噬作用。与非激活和 IgE 激活的 BMMCs 的上清液孵育的 WT MΦ 表现出 iNOS 表达增加和 Arg1 水平降低。
IR CD300a 控制 MΦ 的激活状态，其缺失可能会加剧 CD300a-/- 小鼠中所见的炎症状态。此外，MCs 还可以影响 MΦ 的表型转换。这可能部分解释了这些小鼠中 AI 缓解延迟的现象。
