THE SPECIFIC ROLE OF MAPK13 ISOFORM IN AIRWAY BARRIER DYSFUNCTION AND MUCIN REGULATION

Asthma is a complex chronic disease that affects the airways. Despite significant advances in recent years, there is still a lack of information, mainly related to the specific molecular mechanisms involved. We have previously demonstrated the implication of four specific proteins: TLR4, STAT1, AKT1 and MAPK13 in asthma. In this study, we aim to study the specific role of the MAPK13 isoform in the underlying mechanisms of asthma. The human epithelial cell line CALU-3 was cultured at an air-liquid interface. MAPK13 was specifically silenced using siRNA (siRNA + MAPK13) or without it (siRNA - MAPK13). MAPK13 expression was assessed by RT-qPCR, western blot (WB) and immunofluorescence (IF). siRNA + MAPK13 and siRNA - MAPK13 were stimulated on day 3 with different inflammatory stimuli (IL-5, IL-9, IL-13, LPS and TNFα). Epithelial integrity was measured by transepithelial electrical resistance (TEER) on day 0, 3 and 6, and occludin expression by IF on day 6. Mucus production was measured by RT-qPCR and ELISA. siRNA + MAPK13 cells showed significantly lower MAPK13 expression compared to siRNA - MAPK13 cells by RT-qPCR, IF and WB. MAPK13 expression increased after stimulation with IL-13 and LPS, mainly in siRNA - MAPK13. MAPK13 silencing has a significant impact on epithelial barrier integrity, with lower TEER results compared to non-silenced cells. This is also consistent with reduced occludin expression. Stimulation with IL-13 significantly reduced TEER values in both cells, while IL-5, IL-9 and TNFα did not affect epithelial barrier integrity, with only LPS capable of increasing TEER values. Mucin production appears to increase when MAPK13 is silenced, but the different stimuli increased its production in siRNA - MAPK13, remaining at low levels when MAPK13 was silenced. The specific isoform MAPK13 appears to be significantly involved in airway barrier integrity and mucus production, mainly