Lower expression of TLR4, CCR5 and CD80 in ECs from young
donors
To confirm the RNA-seq and qRT-PCR results and to further explore
probable immunoregulatory mechanisms of ECs, we determined the
expression of TLR4, CCR5, and costimulatory molecules such as CD80 and
CD86 in young and old BM ECs by flow cytometry after 4 hours of LPS
stimulation. Fig. 5 shows the representative gating strategy for the
expression of TLR4, CCR5, CD80 and CD86 (left panel) and their expressed
frequencies (right panel) in ECs from the young and old donor groups.
The frequencies of TLR4+ ECs (Fig. 5A, 4.16% ±0.82%
vs. 10.39% ± 1.32%, P =0.0001), CCR5+ ECs
(Fig. 5B, 4.8% ±0.89% vs. 10.05% ± 1.47%, P =0.001), and
CD80+ ECs (Fig. 5C, 5.62% ±0.78% vs. 10.67% ±
1.25%, P =0.002) in young donors were markedly lower than those
in old donors. The percentage of CD86+ ECs (Fig. 5D,
13.51% ±0.98% vs. 16.53% ± 1.22%, P =0.08) was lower in young
donors than in old donors, although the result was not statistically
significant.