Möllerherm Helene, Meier Karsten, Schmies Kathrin, Fuhrmann Herbert, Naim Hassan Y, von Köckritz-Blickwede Maren, Branitzki-Heinemann Katja
Department of Physiological Chemistry, University for Veterinary Medicine Hannover, Hanover, Germany.
Faculty of Veterinary Medicine, Institute of Biochemistry, University of Leipzig, Leipzig, Germany.
Front Immunol. 2017 Nov 30;8:1665. doi: 10.3389/fimmu.2017.01665. eCollection 2017.
Mast cells (MCs) are long-living multifunctional innate immune cells that originate from hematopoietic precursors and specifically differentiate in the destination tissue, e.g., skin, respiratory mucosa, intestine, where they mediate immune cell recruitment and antimicrobial defense. these tissues have characteristic physiological oxygen levels that are considerably lower than the atmospheric oxygen conditions (159 mmHg, 21% O; 5% CO) traditionally used to differentiate MCs and to study their functionality . Only little is known about the impact of physiological oxygen conditions on the differentiation process of MCs. This study aimed to characterize the differentiation of immature murine bone marrow-derived MCs under physioxia (7% O; 53 mmHg; 5% CO). Bone marrow-derived suspension cells were differentiated in the presence of interleukin-3 with continuous, non-invasive determination of the oxygen level using a Fibox4-PSt3 measurement system without technique-caused oxygen consumption. Trypan blue staining confirmed cellular viability during the specified period. Interestingly, MCs cultivated at 7% O showed a significantly delayed differentiation rate defined by CD117-positive cells, analyzed by flow cytometry, and reached >95% CD117 positive population at day 32 after isolation. Importantly, MCs differentiated under physioxia displayed a decreased transcript expression level of α and selected target genes , and α, but an increase of and expression compared to MCs cultivated under normoxia. Moreover, the production of reactive oxygen species as well as the amount of intracellular stored histamine was significantly lower in MCs differentiated under low oxygen levels, which might have consequences for their function such as immunomodulation of other immune cells. These results show for the first time that physioxia substantially affect maturation and the properties of MCs and highlight the need to study their function under physiologically relevant oxygen conditions.
肥大细胞（MCs）是长寿的多功能固有免疫细胞，起源于造血前体，并在目的地组织（如皮肤、呼吸道黏膜、肠道）中特异性分化，在这些组织中它们介导免疫细胞募集和抗菌防御。这些组织具有特征性的生理氧水平，远低于传统上用于分化MCs并研究其功能的大气氧条件（159 mmHg，21% O₂；5% CO₂）。关于生理氧条件对MCs分化过程的影响，目前所知甚少。本研究旨在表征低氧（7% O₂；53 mmHg；5% CO₂）条件下未成熟小鼠骨髓来源MCs的分化情况。骨髓来源的悬浮细胞在白细胞介素-3存在的情况下进行分化，使用Fibox4-PSt3测量系统连续、无创地测定氧水平，且无技术导致的氧消耗。台盼蓝染色证实了特定时期内细胞的活力。有趣的是，通过流式细胞术分析，在7% O₂条件下培养的MCs显示出由CD117阳性细胞定义的显著延迟的分化率，并且在分离后第32天达到>95%的CD117阳性群体。重要的是，与在常氧条件下培养的MCs相比，在低氧条件下分化的MCs显示出α和选定靶基因的转录表达水平降低，以及α、 、 表达增加。此外，在低氧水平下分化的MCs中活性氧的产生以及细胞内储存的组胺量显著降低，这可能会影响它们的功能，如对其他免疫细胞的免疫调节。这些结果首次表明低氧显著影响MCs的成熟和特性，并强调了在生理相关氧条件下研究其功能的必要性。
