Objective To study the immune regulatory effect of total flavonoids from houttuynia cordata on herpes simplex keratitis(HSK)mice and preliminarily explore its mechanism.Methods A surgical blade to mark the"#"character on the corneal epithelial layer of Balb/c mice and inoculate with I type herpes simplex virus(HSV-1)was used to construct an HSK model.The successfully identified HSK mice were randomly divided into model group,low(75 mg/kg)and high-dose(300 mg/kg)total flavonoids from houttuynia cordata groups,and high-dose total flavonoids from houttuynia cordata+toll like receptor(TLR)2 agonist Pam3CSK4(0.3 mg/kg)group.A control group was also established with 12 mice in each group.During the modeling and administration period,the corneal lesions in mice were observed daily using a slit-lamp microscope and scored.After administration,HE staining was used to observe the pathological changes of the mouse cornea.ELISA was used to detect the levels of interferon-γ(INF-γ),interleukin-2(IL-2),IL-4,and IL-6 in mouse serum.Western blot was used to detect the protein expression levels of TLR2,myeloid differentiation factor 88(MyD88),nuclear factor-kappaB p65(NF-κB p65)and p-NF-κB p65 in mouse corneal tissue.Results Compared with the control group,the model group mice showed corneal edema,ulcers,and neovascularization,with severe corneal damage and a large number of inflammatory cell infiltration.The serum levels of INF-γ and IL-2 significantly decreased,while the levels of IL-4 and IL-6 significantly increased(P<0.01).The protein expression levels of TLR2 and MyD88 and protein ratios of p-NF-κB p65/NF-κB p65 in corneal tissue significantly increased(P<0.01).Compared with the model group,the low and high dose of total flavonoids from houttuynia cordata groups showed improved corneal injury,the corneal lesion score significantly dereased(P<0.01).The serum levels of INF-γ and IL-2 significantly increased,while the levels of IL-4 and IL-6 significantly decreased(P<0.01).The protein expression levels of TLR2 and MyD88 and protein ratios of p-NF-κB p65/NF-κB p65 in corneal tissue significantly decreased(P<0.01).However,the TLR2 agonist Pam3CSK4 partially reversed the improvement effects of total flavonoids from houttuynia cordata on keratitis and immune imbalance in HSK mice.Conclusion The total flavonoids of houttuynia cordata can effectively improve corneal damage,regulate immune response,and suppress inflammation levels in HSK mice.Its mechanism of action may be related to the regulation of TLR2/NF-κB signaling pathway.

Objective To study the immune regulatory effect of total flavonoids from houttuynia cordata on herpes simplex keratitis(HSK)mice and preliminarily explore its mechanism.Methods A surgical blade to mark the"#"character on the corneal epithelial layer of Balb/c mice and inoculate with I type herpes simplex virus(HSV-1)was used to construct an HSK model.The successfully identified HSK mice were randomly divided into model group,low(75 mg/kg)and high-dose(300 mg/kg)total flavonoids from houttuynia cordata groups,and high-dose total flavonoids from houttuynia cordata+toll like receptor(TLR)2 agonist Pam3CSK4(0.3 mg/kg)group.A control group was also established with 12 mice in each group.During the modeling and administration period,the corneal lesions in mice were observed daily using a slit-lamp microscope and scored.After administration,HE staining was used to observe the pathological changes of the mouse cornea.ELISA was used to detect the levels of interferon-γ(INF-γ),interleukin-2(IL-2),IL-4,and IL-6 in mouse serum.Western blot was used to detect the protein expression levels of TLR2,myeloid differentiation factor 88(MyD88),nuclear factor-kappaB p65(NF-κB p65)and p-NF-κB p65 in mouse corneal tissue.Results Compared with the control group,the model group mice showed corneal edema,ulcers,and neovascularization,with severe corneal damage and a large number of inflammatory cell infiltration.The serum levels of INF-γ and IL-2 significantly decreased,while the levels of IL-4 and IL-6 significantly increased(P<0.01).The protein expression levels of TLR2 and MyD88 and protein ratios of p-NF-κB p65/NF-κB p65 in corneal tissue significantly increased(P<0.01).Compared with the model group,the low and high dose of total flavonoids from houttuynia cordata groups showed improved corneal injury,the corneal lesion score significantly dereased(P<0.01).The serum levels of INF-γ and IL-2 significantly increased,while the levels of IL-4 and IL-6 significantly decreased(P<0.01).The protein expression levels of TLR2 and MyD88 and protein ratios of p-NF-κB p65/NF-κB p65 in corneal tissue significantly decreased(P<0.01).However,the TLR2 agonist Pam3CSK4 partially reversed the improvement effects of total flavonoids from houttuynia cordata on keratitis and immune imbalance in HSK mice.Conclusion The total flavonoids of houttuynia cordata can effectively improve corneal damage,regulate immune response,and suppress inflammation levels in HSK mice.Its mechanism of action may be related to the regulation of TLR2/NF-κB signaling pathway.