Figures & data
Figure 1 Pretreatment with exogenous TNF-α attenuates the endogenous TNF-α response to lipopolysaccharide.
Notes: exogenous TNF-α induces production of endogenous TNF-α in a dose-dependent manner (A). In cells pretreated with various concentrations of TNF-α, the subsequent production of TNF-α protein in response to lipopolysaccharide is attenuated in a dose-dependent manner (B). Data are representative of the mean ± standard deviation of two independent experiments analyzed in triplicate. Statistically significant compared with no TNF-α pretreatment control (*P<0.05, student’s t-test).
Abbreviation: TNF-α, tumor necrosis factor-alpha.
Figure 2 Exogenous TNF-α induces tolerance to subsequent TNF-α and LPS challenges.
Notes: THP-1 cells were stimulated with TNF-α (A, black bars) or LPS (B, striped bars) for 2 hours at which point they were washed and incubated with fresh medium for 14 hours before being challenged with TNF-α or LPS for 2 hours (C, black bars: primary stimulation TNF-α; striped bars: primary stimulation LPS). The nominal concentration of exogenous TNF-α was subtracted when preparing this graph. TNF-α or LPS induced tolerance to challenges from either stimulus. Data are representative of the mean ± standard deviation of two independent experiments analyzed in duplicate. Statistically significant compared with primary stimulations (*P<0.05, student’s t-test).
Abbreviations: TNF-α, tumor necrosis factor-alpha; LPS, lipopolysaccharide.
Figure 3 Neutralizing soluble TNF-α and antagonistic TNF-α receptor antibodies impair the production of proinflammatory mediators in LPS-stimulated THP-1 cells.
Notes: The concentration of TNF-α detected from LPS-stimulated THP-1 treated with anti-TNF-α or TNF-α receptor antibodies was significantly attenuated (A). In addition, impairing TNF-α signaling attenuated the production of the proinflammatory cytokine, IL-1β (B). These data suggest that TNF-α signaling plays a prominent role in the induction of other proinflammatory mediators during LPS stimulation. Data representative of mean ± standard deviation of two independent experiments analyzed in duplicate. Statistically significant compared with no antibody controls (*P<0.05, student’s t-test).
Abbreviations: TNF-α, tumor necrosis factor-alpha; TNFR 1/II, tumor necrosis factor receptor I and II; LPS, lipopolysaccharide; IL-1β, interleukin-1β.
Figure 4 Neutralizing soluble TNF-α and antagonist TNF-α receptor antibodies do not attenuate the induction of LPS tolerance in THP-1 cells.
Notes: The concentration of TNF-α detected from LPS-stimulated THP-1 treated with anti-TNF-α or anti-TNF-α receptor antibodies was significantly attenuated during the primary LPS stimulation (A, striped bars). Impairing TNF-α signaling during the primary stimulation did not result in a reduced degree of tolerance (A, black bars). There were no lingering effects of the antibodies added during the primary stimulation as both control cells (B, white bars) and TNF-α-stimulated cells (B, black bars) did not display tolerance when challenged with LPS. Data are representative of the mean ± standard deviation of two independent experiments analyzed in duplicate. Statistically significant when compared with no antibody controls (*P<0.05, student’s t-test).
Abbreviations: TNF-α, tumor necrosis factor-alpha; TNFR 1/II, tumor necrosis factor receptor I and II; LPS, lipopolysaccharide.
