Bidirectional Crosstalk between C5a Receptors and the NLRP3 Inflammasome in Macrophages and Monocytes

Figure 3

C5a robustly enhances TLR4-mediated IL-1β production in bone marrow inflammatory monocytes but not neutrophils. bone marrow cells were plated and cultured for 4 hours with or without LPS (100 ng/mL) in the absence or presence of C5a (1,000 ng/mL). Intracellular IL-1β staining was performed to determine the relative contributions of monocytes (CD11b⁺Ly6C⁺) and neutrophils (CD11b⁺Ly6G⁺) to the elevated bone marrow IL-1β response observed during LPS and C5a cotreatment (a). IL-1β MFI was measured to quantify the effect of C5a on LPS-induced IL-1β production (b). Numbers included in (a) refer to flow cytometry gates. Cell percentages and MFI values are expressed as means ± standard error of the mean. Experiments were performed in triplicate for ≥2 independent experiments, and representative results are shown. Data indicated that inflammatory monocytes in the bone marrow are uniquely sensitive to C5a’s NLRP3-enhancing effects. MFI = mean fluorescence intensity; Neg. Ctrl. = negative (unstimulated) control.

(a)

(b)