The p38 MAPK and NF-κB Pathways are Involved in Cyclic Compressive Force-induced IL-6 Secretion in MLO-Y4 Cells

Abstract

We previously revealed the involvement of extracellular regulated protein kinases 1/2 (ERK1/2) in interleukin-6 (IL-6) secretion induced by cyclic compressive force (CCF) in MLO-Y4 cells. In this study, we investigated the contributions of the p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways to IL-6 secretion by stimulating MLO-Y4 cells with CCF. At 80% confluence, different magnitudes (1000μstrain, 2000 μstrain and 4000 μstrain), frequencies (0.5 Hz, 1.0 Hz and 2.0 Hz) and durations (10 min, 30 min, 1 h, 3 h and 6 h) of CCF were loaded onto cells using a four-point bending system. Flow Cytometry (FCM) analysis was used to analyze cell mortality rates after CCF loading. p38 and p65 phosphorylation as well as IκBα degradation in MLO-Y4 cells were detected by Western blotting (WB). Changes in IL-6 secretion after inhibitor treatment were assessed by enzyme-linked immunosorbent assays (ELISAs). Cellular viability was over 90 percent after CCF. p38 and p65 phosphorylation increased under all conditions, whereas IκBα protein levels decreased. However, phosphorylation and degradation were not completely dependent on the loading magnitude, frequency or duration. Furthermore, p38 inhibition using the specific inhibitor SB203580 reduced both p38 phosphorylation and IL-6 secretion. Similarly, NF-κB inhibition using BAY 11-7082 decreased p65 phosphorylation and IL-6 secretion but increased the concentration of IκBα. These findings reveal significant roles for the p38 and NF-κB signaling pathways in IL-6 secretion induced by CCF in MLO-Y4 cells.

Toxicity and Anti-Inflammatory Activity of Phenolic-Rich Extract from Nopalea cochenillifera (Cactaceae): A Preclinical Study on the Prevention of Inflammatory Bowel Diseases

“…The inflammatory cytokines can trigger the pathway of MAPKs, and the extracellular regulated kinases (ERK1/2), p38 MAPK and JNK represent the three primary MAPK signaling pathways [ 78 ]. The NF-κB and MAPKs pathways are closely linked with IBD [ 79 ], and therefore, NCHE may improve inflammation for DNBS-induced colitis by modulating both pathways.…”

“…In this study, a decrease in gene and protein expression of NF-kB is evidenced in the SSZ and NCHE. The mitogen-activated protein kinases (MAPK) signaling is the other important extracellular signal transduction pathway stimulated by inflammatory mediators [ 78 , 79 ].…”