Anmerkungen:
Hinweis: Link zur Erstveröffentlichung URL: https://doi.org/10.3389/fimmu.2017.01665
Beschreibung:
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. In vivo these tissues have characteristic physiological oxygen
levels that are considerably lower than the atmospheric oxygen conditions (159 mmHg,
21% O2; 5% CO2) traditionally used to differentiate MCs and to study their functionality
in vitro. 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 in vitro (7% O2; 53 mmHg;
5% CO2). 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% O2 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 hif-1α and selected target genes
vegf, il-6, and tnf-α, but an increase of foxo3 and vhl 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.