Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Ciências Biológicas, Bauru, SP, Brasil.
Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Estomatologia (Patologia Oral), Bauru, SP, Brasil.
J Appl Oral Sci. 2021 Mar 31;29:e20200770. doi: 10.1590/1678-7757-2020-0770. eCollection 2021.
Neutrophils are key effector cells of the innate immune system. They recognize antigens through membrane receptors, which are expressed during their maturation and activation. Neutrophils express FcγRII (CD32), FcγRIII (CD16), and FcγRI (CD64) after being activated by different factors such as cytokines and bacterial products. These receptors are involved with phagocytosis of IgG-opsonized microbes and enhance defense mechanisms. Based on that, our study seeks to compare the expression of FcγRII, FcγRIII, FcγRI, and CD11b on neutrophils from elderly and young subjects and their expression after in vitro activation with cytokines and LPS.
Neutrophils were isolated from human peripheral blood and from mice bone marrow by density gradient. After isolation, FCγRs expression was immediately analyzed by flow cytometry or after in vitro stimulation.
In freshly isolated cells, the percentage of FcγRIIIb+ and CD11b+ neutrophils were higher in samples from young individuals; FcγRIIIa expression was more prominent on aged neutrophils; FcγRIA expression was similar in all samples analyzed. Exposure to CXCL8 and LPS resulted in a higher percentage of FcγRIa+ neutrophils on elderly individuals' samples but lower when compared with neutrophils from young donors. We observed that LPS caused an increase in FcγRIIa expression on aging human neutrophils. In contrast, FcγRIIIb expression in response to CXCL8 and LPS stimulation was not altered in the four groups. CD11b expression was lower in neutrophils from elderly individuals even in response to LPS and CXCL8. In mice, we observed differences only regarding CD11b expression, which was increased on aged neutrophils. LPS exposure caused an increase in all FcγRs.
Our results suggest that, in humans, the overall pattern of FcγR expression and integrin CD11b are altered during aging and immunosenescence might contribute to age-related infection.
中性粒细胞是先天免疫系统的关键效应细胞。它们通过膜受体识别抗原，这些受体在成熟和激活过程中表达。中性粒细胞在被细胞因子和细菌产物等不同因素激活后，表达 FcγRII（CD32）、FcγRIII（CD16）和 FcγRI（CD64）。这些受体参与 IgG 调理微生物的吞噬作用，并增强防御机制。基于此，我们的研究旨在比较老年和年轻受试者中性粒细胞 FcγRII、FcγRIII、FcγRI 和 CD11b 的表达及其与细胞因子和 LPS 体外激活后的表达。
通过密度梯度从人外周血和小鼠骨髓中分离中性粒细胞。分离后，通过流式细胞术或体外刺激后立即分析 FCγR 表达。
在新鲜分离的细胞中，年轻个体样本中 FcγRIIIb+和 CD11b+中性粒细胞的百分比更高；FcγRIIIa 在老年中性粒细胞上的表达更为突出；所有分析样本中 FcγRIA 的表达相似。CXCL8 和 LPS 暴露导致老年个体样本中 FcγRIa+中性粒细胞的百分比增加，但与年轻供体的中性粒细胞相比则较低。我们观察到 LPS 导致衰老人类中性粒细胞中 FcγRIIa 表达增加。相比之下，CXCL8 和 LPS 刺激对四个组的 FcγRIIIb 表达没有改变。即使在 LPS 和 CXCL8 刺激下，老年个体的中性粒细胞中 CD11b 的表达也较低。在小鼠中，我们仅观察到 CD11b 表达的差异，老年中性粒细胞的 CD11b 表达增加。LPS 暴露导致所有 FcγR 表达增加。
我们的研究结果表明，在人类中，FcγR 表达和整合素 CD11b 的整体模式在衰老过程中发生改变，免疫衰老可能导致与年龄相关的感染。
