Immunomodulatory Effects of Hypertonic Saline: The Effects on Nuclear Translocation of NF-kappaB and TNF-alpha Synthesis in Stimulated PMNs

ABSTRACT

PURPOSE: According to current research, hypertonic saline has immunomodulatory effects. NF-kappaB is known as an important transcription factor involved in the production of inflammatory mediators during an inflammatory response. The purpose of this study was to determine the effect of hypertonic saline on both the NF-kappaB signaling pathway and on TNF-alphasynthesis in stimulated PMNs. METHODS: Isolated PMNs from healthy volunteers were subdivided into 3 groups by the incubation conditions control (not stilmulated, isotonic condition), isotonic (stimulated, isotonic condition), hypertonic (stimulated, hypertonic condition). After nuclear proteins were isolated from the incubated PMNs, NF-kappaB was measured by Western blot. TNF-alpha was measured by ELISA from the culture media. RESULTS: The relative densities of nuclear NF-kappaB after 45 minute incubation were 0.28+/-0.14 (control group), 0.97+/- 0.16 (isotonic group), and 0.58+/-0.07(hypertonic group). Isotonic and hypertonic groups (fMLP stimulated groups) showed a significantly higher relative density than control groups. Among the study groups, the hypertonic groups had a smaller increased level compared to isotonic groups and were found to be statistically significant. The results from the 90 minute incubated groups were similar to that of the 45 minute incubated groups. The concentration of TNF- alphameasured from stimulated groups (isotonic group, hypertonic group) were significantly higher than control groups. Similar to the NF-kappaB result, the concentrations of TNF-alphain the hypertonic groups were significantly lower than isotonic groups. Longer incubation times were noted to display higher concentration in the stimulated groups. CONCLUSION: Stimulated PMNs incubated under hypertonic conditions showed a smaller increase in level of nuclear NF-kappaB and TNF-alphasynthesis compared to isotonic conditions. As a result, suppression of the NF-kappaB signaling pathway in stimulated PMNs is considered one of the mechanisms of hypertonic saline's immunomodulatory effect.