Hibiscus syriacus Leaves Upregulate p62/SQSTM1 through TLR4/p38, JNK, and NF-κB/Nrf2 Signaling Pathway in RAW264.7 Cells

Hibiscus syriacus Leaves Upregulate p62/SQSTM1 through TLR4/p38, JNK, and NF-κB/Nrf2 Signaling Pathway in RAW264.7 Cells

Autophagy contributes to enhancing the immune system (innate and adaptive immune system) against foreign pathogens. Autophagy of macrophages is used as a major indicator for developing vaccine adjuvants to increase the adaptive immune response. In this study, HSL increased p62/SQSTM1 expression. Inhibition of TLR4, p38, JNK, and NF-κB blocked HSL-mediated increase of p62/SQSTM1. HSL activated p38, JNK, and NF-κB signaling, but HSL-mediated activation of p38, JNK, and NF-κB signaling was reversed by TLR4 inhibition. In addition, HSL increased Nrf2 expression, but HSL-mediated Nrf2 expression did not occur in the inhibition of TLR4, p38, JNK, and NF-κB. Taken together, it is believed that HSL-mediated autophagy may be dependent on activating Nrf2 expression via TLR4-dependent activation of p38, JNK, and NF-κB in macrophages.