Efficacy of caerulomycin A in modulating macrophage polarization and cytokine response in a murine model of lipopolysaccharide-induced sepsis

Background: Sepsis is characterized by an excessive immune response. Modulation of the immune response, particularly macrophage polarization, may provide therapeutic benefit. The effects of Caerulomycin A (caeA), a known STAT1 phosphorylation inhibitor, on macrophage polarization and inflammatory markers were explored using a lipopolysaccharide (LPS)-induced sepsis mouse model.

Methods: A sepsis model was established in C57BL/6 mice induced by intraperitoneal injection of LPS, and the survival rate of mice was observed after treatment with different doses of caeA to determine the optimal therapeutic dose. For in-vitro assays using the RAW264.7 macrophage cell line, the concentration of caeA that was non-toxic to cell survival was screened using the MTT assay, followed by the analyses by qRT-PCR, ELISA, Western blot and flow cytometry for M1/M2 type macrophage markers (CD86, NOS2, CD206, ARG1) and inflammatory factors (IL-1β, IL-6, TNF-α, IL-4, and IL-10) expression. In addition, the phosphorylation levels of STAT1 and STAT6 in the JAK-STAT signaling pathway were detected.

Results: The results of in-vivo experiments showed that caeA treatment (20 mg/kg) significantly increased the survival of LPS-induced septic mice and decreased the expression of M1-type macrophage markers (CD86 and NOS2) and pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) while increasing the expression of M2-type markers (CD206 and ARG1) and anti-inflammatory cytokines (IL-4 and IL-10) expression. In in-vitro experiments, 20 μM caeA effectively inhibited LPS-induced polarization of M1-type macrophages without affecting the activity of RAW264.7 cells, and caeA significantly inhibited the phosphorylation of STAT1 yet enhanced the phosphorylation level of STAT6, as detected by Western blot.

Conclusions: CaeA effectively modulates macrophage polarization and attenuates the inflammatory response in septic mice, possibly by affecting the JAK-STAT signaling pathway. These findings support further exploration of the potential of caeA as a therapeutic agent for sepsis.

Caerulomycin A; Cytokine modulation; Immunomodulation; Macrophage polarization; Sepsis therapy.