Geniposide Inhibited Lipopolysaccharide-induced Apoptosis by Modulating TLR4 and Apoptosis-related Factors in Mouse Mammary Glands

AimsGeniposide, a major iridoid glycoside found in gardenia fruit, is widely used in Asian countries for its anti-inflammatory, anti-tumor and anti-apoptotic activities. Although the anti-inflammatory effect of geniposide has been widely reported, its anti-apoptotic role in mastitis remains unclear. In the present study, we investigated whether geniposide exerts anti-apoptotic activity in lipopolysaccharide (LPS)-induced mouse mammary glands.Main methodsWe established a LPS-induced mouse mastitis model and LPS-stimulated primary mouse mammary epithelial cells (mMECs) model to investigate the anti-apoptotic effect of geniposide and the underlying mechanism of action. In the in vivo studies, apoptosis in mammary glands was detected by TUNEL. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to analyze the expression of Bax, Bcl-2, Caspase-3 and p53. In the in vitro study, the apoptosis in mammary epithelial cells was measured by Live-Dead staining. Western blot and qRT-PCR analysis were used to analyze the expression of Bax, Bcl-2, Caspase-3, p53 and TLR4.Key findingsGeniposide alleviated mammary gland apoptosis, down-regulated Bax expression, inhibited Caspase-3 cleavage and p53 phosphorylation and up-regulated Bcl-2 expression in vivo. In vitro, geniposide decreased the ratio of dead cells in a dose-dependent manner. Geniposide inhibited Bax expression and Caspase-3 cleavage, and up-regulated the expression of Bcl-2. Moreover, geniposide down-regulated the expression of TLR4 and repressed the phosphorylation of p53.SignificanceThese results demonstrate that the anti-apoptotic property of geniposide is due to its modulation of TLR4 and apoptosis-related factors (p53, Bax, Bcl-2 and Caspase-3) in LPS-induced mouse mastitis.