Abstract P67: Hyperosmolar Treatment of Pulmonary Epithelium Produces Conflicting Cytokine Production Despite NF-kB Inhibition
We and others have shown that hyperosmolarity (HOsm) attenuates inflammatory signaling in neutrophils or endothelium but the generality of this treatment and mechanisms remain unclear. Since both TNFa and IL-1b induce lung chemokine production, the purpose of this study was to investigate the benefits of HOsm on pulmonary epithelium.
Hypothesis: Treatment with HOsm attenuates inflammatory effects driven by NF-kB activity.
Methods: Human pulmonary epithelial cells were incubated with hypertonic saline (HTS) or sorbitol (SOR) augmented media at 400 mOsm for 30 minutes prior to TNF or IL-1 (10ng/ml) stimulation. I-êB phosphorylation was measured using ELISA. Cytokines were measured using ELISA and immunofluorescent bead arrays.
Results: HTS and SOR both inhibited chemokine production (RANTES: 90 –95% vs normal media, p<0.001 n=4) stimulated by either TNFa or IL-1b. However, physiological HOsm exerted by HTS or SOR increased IL-8 production with both TNF and IL-1 stimulation (60 –70% increase vs normal media, p < 0.001 with TNF and 35– 45% increase, p < 0.05 with IL-1, n=4). Furthermore HOsm decreased I-êB phosphorylation with both stimuli (p < 0.01, n=4). No significant differences were seen between HTS and SOR treatment in any group.
Conclusion: In lung epithelium, HOsm presents a complex picture with respect to inflammatory cytokines and NF-kB activity. HOsm suppresses RANTES but stimulates IL-8. Decreased phosphorylation of I-kB by HOsm treatment suggests that NF-kB activation should be diminished, however expression of certain NF-kB driven genes increase with HOsm. This suggests that HOsm might comprehensively suppress adverse lung-leukocyte interactions despite elevated IL-8 production.