Anemoside B4 alleviates DSS-induced colitis by inhibiting CD1d-dependent
NLRP3 inflammasome activation in macrophages
Abstract
Background and Purpose: Abnormal activation of the NLRP3 inflammasome in
macrophages is closely associated with Ulcerative colitis (UC), and
targeting the NLRP3 inflammasome has been proposed as a potential
therapeutic approach, but the underlying mechanism by which it regulates
intestinal inflammation remains unclear. Anemoside B4 (AB4) has
anti-inflammatory activity, but whether it alleviates UC by inhibiting
the activation of NLRP3 inflammasome remains unclear. More importantly,
the molecular targets of AB4 remain unknown. Experimental Approach: We
explored the role of AB4 in the development of dextran sodium sulfate
(DSS)-induced colitis in wild-type (WT) mice and its effect on NLRP3
inflammasome. We isolated intestinal macrophages and epithelial cells,
and validated them in DSS-induced NLRP3-deficient (NLRP3-/-) mice. The
target and molecular mechanism of AB4 were identified in LPS-induced
macrophages in vitro and DSS-induced macrophage-specific CD1d depletion
(CD1d-/-) mice in vivo. Key Results: This study showed that AB4 had a
strong anti-inflammatory effect DSS-induced colitis in WT mice, whereas
the protective effects were lost in NLRP3-/- mice. AB4 inhibited the
activation of NLRP3 inflammasome in colonic macrophages without
affecting intestinal epithelial cells. Mechanistically, AB4 might target
CD1d thus reducing the AKT-STAT1-PRDX1-NF-κB signaling pathway,
eventually inhibiting the activation of NLRP3 inflammasome.
Macrophage-specific CD1d depletion had been shown to reverse the
protective effect of AB4. Conclusions and Implications: Our data showed
that AB4 attenuated DSS-induced colitis by inhibiting CD1d-dependent
NLRP3 inflammasome activation in macrophages. Therefore, as a natural
product with high safety index, AB4 might be considered a promising
candidate drug for the treatment of colitis.