The RNA-binding protein KSRP reduces asthma-like characteristics in a murine model.

Abstract

Background and objective: Asthma is a chronic inflammatory disease characterized by dysregulated cytokine expression. The RNA-binding protein KSRP reduces the expression of several pro-inflammatory mediators. Therefore, we investigated whether KSRP modulates Th2-associated immune responses in vivo in an ovalbumin-induced (OVA) allergic asthma model in C57BL/6 KSRP-deficient mice (KSRP^-/-).

Methods: Asthma severity in OVA-immunized wild type or KSRP^-/- mice was determined by airway hyperresponsiveness (AHR), structural changes of lung tissue, and OVA-specific antibody production. Cytokine expression in bronchoalveolar lavage fluid (BALF) was measured by Cytometric Bead Array (CBA) analysis. Cellular signaling pathways involved in KSRP-mediated effects in asthma pathogenesis were analyzed in vitro in cell culture models using specific inhibitors.

Results: KSRP deficiency exacerbates OVA-induced allergic asthma compared to wild type mice, as indicated by increased AHR, more severe lung damage, goblet cell hyperplasia and increased OVA-specific antibody production. CBA analyses confirmed, that KSRP deficiency enhances IL-4, IL-5 and IL-13 production in BALF. The effect of KSRP on Th2-associated cytokine expression appears to be mediated by modulation of the STAT6 and NFAT signaling pathway rather than by inhibiting the stability of cytokine-encoding mRNA species.

Conclusion: Our data demonstrate that KSRP dampens Th2 immune cell activity and therefore seems to be important for the pathogenesis of Th2-mediated diseases.