Publication Date:
2016-12-02
Description:
Intravascular hemolysis results in the release of damaging hemoglobin and free heme into the circulation. A role for heme as a danger associated molecular pattern (DAMP), with a function in sterile inflammatory responses, is becoming increasingly recognized. Whilst heme has known effects on leukocytes, activating their migration, adhesion molecule expression and cytokine expression, more recent data demonstrate that this molecule can induce NLRP3 inflammasome formation in murine bone marrow macrophages, with consequent interleukin (IL)-1β processing and neutrophil recruitment (Dutra et al., Proc. Natl Acad Sci. 111: E4110, 2014). We aimed to investigate whether heme can also induce inflammasome activation in primary human macrophages (hMACs) and to further characterize the pathways by which heme-induced inflammatory responses may be amplified under sterile conditions. CD14+ cells were separated from human peripheral blood (using anti-CD14 magnetic beads) and differentiated into hMACs under M-CSF media supplementation and in the presence of 10% fetal bovine serum. In vitro results are expressed as means ± SEM for triplicate cultures and are representative of three independent experiments. Priming of hMACs with lipopolysaccharide (LPS; 100 ng/mL; 3h) alone induced low level secretion of IL-1β (14.11±9.2 pg/106 cells, as measured by ELISA), while heme (50 µM), in the absence of pre-stimulation with LPS, was unable to induce significant IL-1β secretion within 3h (2.46±1.4 pg/106 cells). In contrast, co-incubation of hMACs with both LPS and heme for 3h significantly enhanced hMAC IL-1β release (490.3±36.3 pg/106 cells; P
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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