Fig. 3. In vitro exposure to a particulate
pollutant induces trained immunity in human circulating monocytes.Schematic representation of a standard protocol for induction of trained
immunity in monocytes (A). The levels of TNF, IL-6, and IL-8 were
compared in supernatants collected from monocytes under training with
SRM 1648a pollutant (red), or vehicle (blue) after stimulation with
medium, LPS, or HDM. Training of monocytes with SRM1648a pollutant
induced a robust increase in LPS or HDM-mediated elevation of TNF, IL-6,
and IL-8 levels. (N=10 subjects including 7 healthy and 3 asthmatic
children per group) (B). The role of environmental exposure to
PM2.5 on induction of trained immunity was studied by
comparing these mediators in subjects exposed to low (pink) versus high
(purple) levels of ambient PM2.5 (N=5 subjects including
4 healthy and 1 asthmatic children per group) (C). The impact of
re-exposure to pollutant on trained immunity was determined by measuring
the levels of TNF, IL-6, and IL-8 in supernatants (D). The graphs
represent a single set of measurements from one of 2 independent
cytokine experiments. Statistical significance was determined using
non-parametric Wilcoxon sum test.