Anti-inflammatory Effects Of Moxibustion On Mice With Adjuvant Arthritis: Role Of TRPV1

Backgrounds.Inflammation is a local, protective response to microbial invasion or injury. The magnitude of the inflammatory response is crucial in different diseases:insufficient responses result in immunodeficiency, which can lead to infection and cancer; excessive responses cause rheumatoid arthritis, Crohn’s disease, atherosclerosis, diabetes, Alzheimer’s disease.etc. So,inflammatory response is considered to be the common pathway of most important diseases. Numerous of clinical studies have found that the warm-heat stimulation of moxibustion is the premise and foundation of anti-inflammatory effect playing. The transient receptor potential vanilloid (TRPV) 1 receptor is a nonselective cation channel. Many studies show that TRPV1 plays a key role in inflammation,and topical application of capsaicin has the effects of anti-inflammation. TRPV1 is a temperature sensor which is a member of the TRP family, TRPV1 can be activated by heat stimulation of> 43℃,which is similar to the local skin temperature caused by moxibustion clinically.Objectives.To observe the anti-inflammatory effect of moxibustion and explore the role of TRPV1 on Mice with adjuvant arthritis.Methods.Part I:30 Kumming(KM) mice were randomized into 3 groups by random number table method:control group, model group and moxibustion group with 10 mice in each. Adjuvant arthritis was established by using the amount of 20μL of Complete Freund’s Adjuvant(CFA) intradermal injected into right hindfoot plantar except control group. Each mouse in the moxibustion group was given a suspended moxibustion with 5mm*200mm specially-made moxa stick for 20 minutes on L5 and L6 spinal cords. Kept the distance between the moxa stick and the skin where L5 and L6 spinal cords located was 12±2 mm that the temperature was stabilized at 44℃±1℃. All the treatments above were performed at the same day when models were successfully established,and performed once per day for 7 days in total.During the performance,mice in the control group,model group were of no treatment in any way. The right hindfoot paw volumes of mice in each group were measured and recorded on Day l,Day 2,Day 4,Day 6and Day 8 of the experiment. Draw materials after all treatments, the serum IL-1β and TNF-α level was determined by ELISA. Part II:60 KM mice were randomized into 6 groups by random number table method:control group,model group, capsaicin group capsazepine group,moxibustion group and moxibustion+capsazepine(MC) group with 10 mice in each. Adjuvant arthritis was established by using the amount of 20μL of Complete Freund’s Adjuvant(CFA) intradermal injected into right hindfoot plantar except control group. Each mouse in the capsaicin group is subcutaneously injected with the amount of 0.1ml/10g into the L5,L6 spinal cords.Each mouse in the capsazepine group was intraperitoneally injected with the amount of 0.1ml/10g. Each mouse in MC group was intraperitoneally injected with the amount of 0.1ml/10g first, then after 15 minutes was given a suspended moxibustion for 20 minutes on L5 and L6 spinal cords. All the treatments above were performed at the same day when models were successfully established,and performed once per day for 7 days in total.During the performance,The treatments of mice in the control group,model group and moxibustion group was the same as the Part Ⅰ.The indexes detected was the same as the Part Ⅰ. Part Ⅲ:16 C57BL/6 wild-type mice are randomized into 2 groups by random number table method: wild-type(WT) model group and WT moxibustion group with 8 in each.14 TRPV1 knockout mice are randomized into 2 groups by random number table method:knockout(KO) model group and KO moxibustion group with 7 in each. Adjuvant arthritis was established by using the amount of 20μL of Complete Freund’s Adjuvant(CFA) intradermal injected into right hindfoot plantar. WT moxibustion group and KO moxibustion group was given a suspended moxibustion with 5mm*200mm specially-made moxa stick for 20 minutes on L5 and L6 spinal cords. Kept the distance between the moxa stick and the skin where L5 and L6 spinal cords located was 12±2 mm that the temperature was stabilized at 44℃±1℃. All the treatments above were performed at the same day when models were successfully established,and performed once per day for 7 days in total.During the performance,mice in the control group,model group, WT model group and KO model group were of no treatment in any way. The indexes detected was the same as the Part Ⅰ.Results.1. Compared with the control group, the paw volumes in the model group was significantly increased(P<0.01),which was indicated that the adjuvant arthritis was successfully established.2. Compared with the model group, the paw volumes, serum IL-1β,TNF-α levels in the capsaicin group, capsazepine group and moxibustion group was significantly decreased(P<0.01),suggesting that all the three had the effect of inhibiting inflammation.3. Compared with the moxibustion group, after the pretreatment by capsazepine,the paw volumes, serum IL-1β,TNF-α levels in MC group were prominently higher than the moxibustion group(P<0.05), suggesting that capsazepine may partly indertict the effect of inhibiting inflammation by moxibustion.4. Compared with the WT model group, WT moxibustion group significantly decreased the paw volumes, serum IL-1β,TNF-α levels(P<0.01).Compared with KO model group,no changes in the paw volumes, serum IL-1β,TNF-α levels in KO moxibustion group, there was no significant difference in between (P> 0.05).Conclusions.TRPV1 plays a central role in the anti-inflammatory effect of moxibustion, while the effect may be lost if lacked of TRPV1-mediated.