Lovastatin derivative dehydrolovastatin ameliorates ulcerative colitis in mice by suppressing NF-κB and inflammatory cytokine expression

Abstract

Ulcerative colitis (UC) is associated with intestinal immune imbalance and inflammatory response. Because dehydrolovastatin (DLVT), a derivative of lovastatin, has been recently shown to inhibit inflammation and relieve immune arthritis induced by chemical stimuli, we studied its effect and possible mechanism on UC induced by dextran sulfate sodium. The BALB/c mice were classified into six groups: normal control group, model group, DLVT high dose group, DLVT low dose group, salazosulfapyridine (SASP) group and lovastatin (LVT) group. The disease activity indices of UC and pathological changes were investigated. The myeloperoxidase (MPO) activity in colon tissue and inflammatory factors such as IL-6, IL-10, IL-17, and TNF-α in the serum were analyzed by ELISA, while the expression of NF-κB p65 protein in colon tissue was detected by immunohistochemistry and western blot. DLVT relieved the disease activity indices and pathological damage of the UC mice. Furthermore, DLVT significantly decreased MPO activity and improved the imbalance of inflammatory cytokines through inhibiting the expression of NF-κB p65. Meanwhile, the positive drug of SASP has a similar effect to DLVT, but the effect of DLVT in both decreasing IL-17, TNF-α, and increasing IL-10 was significantly stronger than that of SASP. These results suggest that DLVT may ameliorates the symptoms of UC.

Keywords: Dehydrolovastatin; Inflammation; NF-κB; Statins; Ulcerative colitis.

Fig. 1. Changes of clinical parameters and disease activity in the mice.

(A) Change of weight loss in the mice; (B) Change of stool occult blood in the mice; (C) Change of stool characteristics in the mice; (D) Change of Disease Activity Index (DAI) in the mice. Data are presented as mean ± standard deviation (n = 10 for each group). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^*p < 0.05, ^**p < 0.01 compared with the model group.

Fig. 2. Changes of colon length and myeloperoxidase (MPO) activity in the mice.

(A) Change of colon length in the mice; (B) Change of MPO activity in the mice. Data are presented as mean ± standard deviation (n = 10 for each group). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^*p < 0.05, ^**p < 0.01 compared with the model group.

Fig. 3. Changes of serum levels of IL-6, IL-10, IL-17, and TNF-α in the mice.

(A) Change of serum IL-6 level in the mice; (B) Change of serum IL-17 level in the mice; (C) Change of serum TNF-α level in the mice; (D) Change of serum IL-10 level in the mice. Data are presented as mean ± standard deviation (n = 10 for each group). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^**p < 0.01 compared with the model group; ^#p < 0.05, ^##p < 0.01 comparison between the high-dose DLVT group and SASP group.

Fig. 4. Histological changes of colon tissue in the mice.

(A) Histopathological HE staining of colon tissue at high-power visual fields (20×). Arrows mean exudation and inflammatory cells infiltration; (B) Histological injury score. Data are presented as mean ± standard deviation (n = 10 for each group). (A-a) Normal control group; (A-b) model group; (A-c) model group treated with high dose of DLVT (33.6 mg/kg); (A-d) model group treated with low dose of DLVT (16.8 mg/kg); (A-e) model group treated with SASP (250 mg/kg); (A-f) model group treated with LVT (16.8 mg/kg). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^*p < 0.05, ^**p < 0.01 compared with the model group.

Fig. 5. Expression of NF-κB p65 protein of colon tissue in the mice.

(A) Immunohistochemical staining of colon tissue at high-power visual fields (20×); (B) area integral optical density (AIOD). Data are presented as mean ± standard deviation (n = 10 for each group). (A-a) Normal control group; (A-b) model group; (A-c) model group treated with high dose of DLVT (33.6 mg/kg); (A-d) model group treated with low dose of DLVT (16.8 mg/kg); (A-e) model group treated with SASP (250 mg/kg); (A-f) model group treated with LVT (16.8 mg/kg). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^**p < 0.01 compared with the model group.

Fig. 6. Western blot.

(A) Western blot results of NF-κB p65 protein expression; (B) Western blot results of NF-κB p65 protein levels were shown as the target/β-actin ratio of relative light unit values. Data are presented as mean ± standard deviation (n = 10 for each group). (a) Normal control group; (b) model group; (c) model group treated with high dose of DLVT (33.6 mg/kg); (d) model group treated with low dose of DLVT (16.8 mg/kg); (e) model group treated with SASP (250 mg/kg); (f) model group treated with LVT (16.8 mg/kg). DLVT, dehydrolovastatin; LVT, lovastatin; SASP, salazosulfapyridine. ^**p < 0.01 compared with the model group.