The Efficacy And Anti-Inflammatory Molecular Mechanisms Of Aqueous Extract Of Houttuynia Cordata Thunb In Treatment Of An Endotoxin-Induced Uveitis(EIU) Rat Model

Objective To investigate the suppressive effect of water extract of aqueous extract of houttuynia cordata thunb on endotoxin-induced uveitis and its possible mechanism.Methods 12 male Lewis rats were randomly divided into four groups:blank control group,model group,houttuynia cordata thunb group and dexamethasone group(positive control group),with 3 rats in each group.Except for the blank control group,all other three groups were injected with lipopolysaccharide(1.0 mg/kg)by foot pad to construct the endotoxin-induced uveitis rats;while the blank control group was injected with an equal volume of saline.Meanwhile,10 μL of vitreous injection of dexamethasone(10 μg/μL)was given immediately to the dexamethasone group,20 μL(10μg/μL)of aqueous extract of Houttuynia cordata Thunb was given to the houttuynia cordata thunb group,and 20 μL of saline was given to the model group.After 24 h,the degree of uveitis was observed and rated by slit lamp microscopy,and the infiltrating cell count and total protein quantification in the atrial water were also detected.The rat ocular tissues were taken for pathological section observation.At the cellular level,rat retinal cells were isolated and cultured,and the Control group,LPS group,LPS+normal saline group and LPS+Houttuynia cordata Thunb group were set up.The expression levels of IL-6 and TNF-α in each group were detected by qPCR.western blot was used to detect the expression changes of three inflammation-related signaling pathways(PI3K/AKT/mTOR,Wnt/β-catenin and NF-κB/MAPK).Results The results of slit lamp microscopy,pathological sections and infiltrating cell counts in atrial water and total protein quantification showed that compared with the blank control group and the model group,the following indicators in the houttuynia cordata thunb group and dexamethasone group were significantly deceased,which included the infiltrating exudate of inflammatory cells near the ciliary stroma,the rating of uveitis under slit lamp microscopy,and the infiltrating cell counts and total protein content(P<0.05).Meanwhile,there was no significant difference between the houttuynia cordata thunb group and dexamethasone group(P>0.05).Also,the results of the in vitro experiments also showed that compared with the LPS group and the LPS+normal saline group,the protein expression of three inflammation-related pathways and the expression levels of inflammatory mediators(IL-6 and TNF-α)was significantly decreased in the LPS+houttuynia cordata thumb group(P<0.05).Conclusion The aqueous extract of houttuynia cordata thunb had an inhibitory effect on LPS-induced uveitis rats,and the mechanism was related to the reduction of IL-6 and TNF-αexpression levels,which might be through the regulation of three signaling pathways,PI3K/AKT/mTOR,Wnt/β-catenin and NF-κB/MAPK.