Taohong Siwu decoction and its components regulate the M1/M2 polarization of macrophages to alleviate inflammatory injury in sepsis via the RAGE

Ethnopharmacological relevance: Sepsis is a fatal disease induced by an abnormal Anti-infection immune response. Macrophage M1/M2 polarization responses are essential for the systemic inflammatory response process in sepsis. Taohong Siwu Decoction (THSWD) is a traditional Chinese medicine (TCM) prescription that has been confirmed to regulate the macrophage M1/M2 polarization to improve inflammatory damage. However, the active components and the mechanisms by which it alleviates inflammatory injury in sepsis remain unclear. Amygdalin (AMY) is an active component found in Persicae Semen. Great attention has been paid to AMY, which is used in pharmacotherapy to manage inflammatory disorders. Further investigation is warranted to determine how AMY, as one of the active components of THSWD, contributes to its anti-sepsis effects and to clarify the underlying mechanism of action.

Aim of the study: This work evaluated the protection of THSWD and AMY, one of its representative active components, against sepsis-related inflammatory injury and the mechanisms involved.

Materials and methods: Using the cecal ligation and puncture (CLP) procedure, this study constructed a sepsis mouse model. Subsequently, histopathology, echocardiography, TUNEL staining and ELISA were conducted to assess the protection of THSWD against inflammatory injury in CLP mice. Network pharmacology, molecular docking, molecular dynamics simulations, cellular thermal shift assay and SPRi were performed for verifying the mechanism of THSWD and its active component Amygdalin (AMY) in improving inflammatory injury in sepsis. Moreover, the protection of AMY against inflammatory injury, as well as its role in regulating M1 macrophage polarization through the RAGE pathway, was investigated using qRT-PCR, Western blotting, immunofluorescence staining, and immunohistochemical staining. In vitro, M1-type polarization was induced in RAW 264.7 cells and BMDMs using LPS stimulation, thereby verifying the effects of AMY. The RAGE inhibitor FPS-ZM1 was also used for further investigation in vitro and in vivo.

Results: In vivo, THSWD significantly protected against inflammation-induced heart and lung tissue injuries in CLP mice. Bioinformatics analysis and Other studies revealed that AMY, an active component of THSWD, might directly regulate RAGE to inhibit inflammatory response damage. AMY protected against inflammatory injury through inhibiting M1 macrophage polarization in sepsis by directly suppressing RAGE/NF-κB/MAPK pathways in vivo. According to our in vitro study results, AMY blocked RAGE activity to mitigate the LPS-mediated M1-type polarization in RAW 264.7 cells and BMDMs. Notably, AMY's protection in vivo and in vitro was not markedly enhanced by combining FPS-ZM1, consistent with the pooled effect of AMY and FPS-ZM1 on a RAGE-related pathway under our experimental conditions.

Conclusions: THSWD and AMY, one of its active components, inhibit M1 macrophage polarization and alleviate inflammatory injury in sepsis, at least partially by targeting RAGE and modulating the RAGE-mediated NF-κB/MAPK signaling pathway.

Amygdalin; Inflammatory injury; M1/M2 polarization; RAGE; Sepsis; THSWD.