The Immunological Mechanisms In Electroacupuncture Treatment Of Ulcerative Colitis

Ulcerative colitis(UC) is a non-specific inflammatory bowel disease. Immune abnormality plays an important role in the pathogenesis of UC. Recent studies have demonstrated that acupuncture at Tsusanli (ST36) has immunoregulatory role. However, its therapeutic effect on UC was seldom reported. In the present study, an animal model of UC was established, in which both changes of some inflammatory indexes (damage scores, colon mass, myeloperoxidase enzyme activity and inflammatory cytokines) and crrelations among these parameters were observed. The therapeutic effect of electroacupuncture(EA) on UC was assessed by investigating its influence on these indexes. Then, its possible mechanism was elucidated which might contribute to new theory of EA.METHODS:Thirty-two male Sprague-Dawley(SD) rats were randomly divided into four groups(n=8): normal control group; UC control group; UC+ST36 group andUC+non-acupoint group. A solution containing ethanol and 2,4,6-trinitrobenzenesulfonic acid (TNBS) was instilled into the distal colon in the rat to set up UC rat model. Colon musocal inflammation and damage were assessed by measuring colon mass, morphologic damage score, MPO activity, serum concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8) and tnmor necrosis factor-alpha (TNF- a ) , and colonic TNF- a mRNA expression level. Morphologic damage was examined under stereomicroscope, opticalmicroscope and electron microscopy. Colonic MPO activity was measured by spectrophotometric method. Serum concentrations of IL-6, IL-8 and TNF- a were determined by radioimmunoassay (RIA). Colonic TNF- a mRNA expression level was analysed by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS:1. There was severe damage of colonic morphology in UC group. Ratio of colonic mass/body mass(mc/mB) and activity of colonic MPO in rats with UC were markedly increased compared with normal control rats (P <0.01). Serum concentrations of IL-6, IL-8 and TNF- a of UC control group were higher than those of normal control rats (P <0.01). Colonic TNF-a mRNA expression level were significantly elevated in rat with UC (P <0. 01 vs normal control group). Moreover, these parameters were highly correlated with each other (P<0.01).2. Morphologic damage was lessened by EA stimulation at ST36. MPO activity and mc/mB were reduced significantly by EA at ST36 (P<0.01,0.05 vs UC control group). Compared with UC control group, serum concentrations of IL-6, IL-8 and TNF- a were markedly decreased in EA stimulation at ST36 group(P<0.01; P <0. 05; P <0. 05) . Down-regulation of colonic TNF- a mRNAexpression level was also observed (P<0.01).3.There was no significant difference between UC control and UC+EA at non-acupoint (P>0.05).CONCLUSION:The contents of pro-inflammatory cytokines were elevated significantly in UC. These proinflammatory cytokines are correlated with disease actively. It indicates that TNF-a ,IL-6 and IL-8 may cause inflammation and immune response. High levels of these cytokines may be implicated in the pathogenesis of UC. Elevations of these cytokines were inhibted by EA stimulation at ST36. EA at ST36 has better therapeutic effects on UC by inhibiting lesion formation grossly and microscopically, lessening MPO activity in and around lesions. Down-regulation on TNF- a ,IL-6 and IL-8 may be involved in its therapeutic mechanism.It is indicated that immnne factors may be the materials which constitute the foundation of the meridian-viscera relationship, and the essence of meridian maybe relate to immunituy.