Polysaccharide derived from Inonotus obliquus inhibits lipopolysaccharide-induced acute endometritis in mice

Endometritis bacterial pathogenic condition that affects both humans and animals develops in the inner lining of the uterus. Inonotus obliquus polysaccharide (IOP), an active cocktail of Inonotus obliquus, has been shown to have a relatively wide range of biological activities and can play a role in various diseases. However, from the currently reported article, there is no information about the anti-inflammatory effect of IPO in the symptoms of lipopolysaccharide (LPS)-induced endometritis. Therefore, this study carefully observed the phenomenon of IOP on the symptoms of endometritis induced by LPS in mice, elucidated the protective mechanism of IOP on the body, and clarified the potential mechanism of IOP.

A total of 72 BALB/c female experimental mice were divided into several groups for comparison. They were the blank control group, the LPS group, the LPS+ IOP group (the effect of IOP dose on mice was also explored, divided into low, medium, and high) and LPS+ amoxicillin group. All groups except control group were infused with LPS into the uterus. The mice of LPS+ IOP groups and LPS+ amoxicillin group were orally administered with IOP or amoxicillin after LPS challenge for 3 hours. Histopathology and myeloperoxidase (MPO) activity were used to detect uterine tissue injury, and cytokine levels were used to measure uterine inflammation. The expression of toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB)-related proteins in the inflammatory signaling pathway was observed.

Pathological and MPO activity analyses revealed that IOP relieved LPS-induced uterine tissue injury. Quantitative reverse transcription-polymerase chain reaction was used to detect and quantitatively study the RNA information of mouse cells, which had high accuracy and sensitivity. From the test results, IOP does effectively control the release of pro-inflammatory cytokines such as interleukin-6 (IL-6), IL-1β, IL-8 and tumor necrosis factor-α (TNF-α), avoiding the body's immune response. Analysis of uterine tissue cell components also confirmed that the expression level of inflammatory mediator-induced nitric oxide synthase (iNOS) was also greatly reduced. Analysis of western blotting results of cell synthesis showed that IOP mainly inhibited the protein expression of TLR4 and myeloid differentiation factor 88 in the body.

This study proved that the mechanism of action of IOP is to inhibit the TLR4/NF-κB signaling pathway to reduce the release of pro-inflammatory cytokines from body cells, thereby alleviating the symptoms of endometritis induced by LPS. Thus, IOP may act as an effective drug in preventing and curing LPS-induced endometritis.