Amelioration of Toll-like Receptor-4 Signaling and Promotion of Mitochondrial Function by Mature Silkworm Extracts in Ex Vivo and in Vitro Macrophages.

OBJECTIVES

The unknown immune-enhancing effects of steamed mature silkworms (Bombyx mori L.), known as HongJam (HJ), were investigated.

METHODS

Supercritical fluid extracts from the White Jade variety of HJ (WJ-SCEs) were applied to in vitro RAW264.7 macrophages (RAWMs) and ex vivo bone marrow-derived macrophages (BMDMs).

RESULTS

WJ-SCE enhanced the proliferation and viability of both RAWMs and BMDMs. Supplementation with WJ-SCE significantly reduced the lipopolysaccharide (LPS)-induced expression of iNOS mRNA and protein, resulting in decreased nitric oxide (NO) production. Additionally, WJ-SCE lowered the mRNA and protein expression of COX-2 and reduced the levels of pro-inflammatory cytokines. The mitochondrial function, ATP levels, and reactive oxygen species levels in LPS-treated macrophages were restored following WJ-SCE treatment. WJ-SCE modulated LPS-Toll-like receptor-4 (TLR-4) signaling by reducing the levels of phosphorylated (p)-p38, p-ERK1/2, and p-p65. WJ-SCE also restored gene expression related to cytokines, chemokines, glucose transport, mitochondrial metabolism, and TLR-4 signaling, suggesting the inhibition of pro-inflammatory M1 macrophage polarization. Furthermore, WJ-SCE enhanced macrophage phagocytic and pinocytotic activity.

CONCLUSIONS

WJ-SCE demonstrated anti-inflammatory effects by inhibiting LPS-induced M1 polarization in both macrophage types, potentially suppressing chronic inflammation while enhancing phagocytosis and pinocytosis.