作者：鞠辉，王光兰，张海燕，赵清喜，魏良洲，刘希双 作者单位：青岛大学医学院附属医院, 山东 青岛 266003 内镜诊疗科; 消化内科
【摘要】 目的 探讨感染后肠易激综合征（piibs）与溃疡性结肠炎（uc）缓解期病人肠黏膜细胞因子的表达，从神经免疫机制分析肠易激综合征（ibs）与炎症性肠病（ibd）的相关性。方法 piibs组病人20例，uc组病人45例，正常对照组30例，结肠镜下取直肠黏膜标本，采用免疫组化方法检测其肠黏膜细胞因子的表达情况。结果piibs病人直肠ifnγ、il2阳性表达高于对照组（χ2=14.012、13.931,p<0.01），而与uc病人比较差异无统计学意义（χ2=2.290、2.323,p>0.05）。piibs病人直肠黏膜p物质（sp）强度均值高于对照组（t=3.722,p<0.01），而与uc病人比较差异无统计学意义（t=1.643,p>0.05）。直肠黏膜ifnγ、il2阳性表达的piibs病人sp强度均值高于对照组（t=2.301、2.252,p<0.05），与uc病人比较差异无统计学意义(t=1.574,1.676,p>0.05)。结论 piibs与ibd之间可能存在某种相关性。
【关键词】 肠易激综合征；结肠炎,溃疡性；p物质；细胞因子类
the incidence of functional disorder of intestine isabout 22%～25% after the bowel is acutely infected. symptoms like ibs occur in some patients when the pathogens, such as enteric virus, bacterium or parasite, have been eliminated and the mucosal inflammation vanished, which is called postinfective irritable bowel syndrome (piibs)[1]. in remission, clinical manifestations of uc often resemble irritable bowel like syndrome (ibls), which is characterized by abdominal pain and diarrhea without gastrointestinal tract and biochemical abnormality. the therapeutic efficacy is not satisfactory with aminosalicylic acid alone[2]. a followup study of the patients with initial diagnosis of ibs indicated that they were at obviously high risk of developing ibd, with a relative risk being 16.3, which suggestive of certain correlation really exists between ibs and ibd[3]. the purpose of this study was to investigate the expressions of sp, ifnγ and il2 in rectal mucosa of patients with piibs and uc in remission, analyze the association between ibs and ibd based on neuroimmunomechanism.
1 materials and methods
1.1 case selection
according to rome criteria ⅱ[4], 45 diarrheaibs patients, 17 men and 28 women, the mean age was 39.17±10.89 years, were randomly recruited from outpatient clinic of gastroenterology at the affiliated hospital of qingdao university medical college. of whom, 20 were classified as piibs meeting the romeⅱcriteria, with a history of acute gastrointestinal tract infection at least one day before appearing ibs symptoms, cured within five days and relapsefree. fortyfive uc patients in remission， 25 men and 20 women, mean age was 40.7±13.5 years. the standards of enrolment were: with a history of uc diagnosed enteroscopically, with symptoms of abdominal pain and diarrhea similar to ibs but without abnormalities of the structure and biochemistry of digestive tract, no obvious signs of congestion, edema or exudation were observed at enteroscopy, and poorly responded to aminosalicylic acid alone. thirty controls, 12 men and 18 women, mean age was 38.45±10.90 years. the standards of enrolment were: at least six months after electroresection of colon polyp and no abnormalities were noticed at followup or coloscopic diagnosis as having hemorrhoid due to slight bloody stools, with no other symptoms and signs of digestive tract. no history of immunologically mediated disease or infection and no recent medication were recorded.
1.2 methods
two pieces of rectal mucosa were taken in each case, fixed in10% formalin, and embedded in paraffin. a 4μm thick serial section was made for all paraffin blocks. he staining, routine pathohistological and immunohistochemical examinations were conducted. with an assistance of a senior pathologist, typical areas not including the margins from every section were chosen to judge the dyeing of ifnγ and il2. the results were graded via positive cell percentage and dyeing intensity and the scores were determined according to cytoplasm coloration[5]. the absorbance was detected for sp quantitative analysis with vidas picture analysis system. the results were analyzed by variance analysis and t test with spss 10.0 statistical pack.
2 results
in the he dyed sections, the rectal mucosa of piibs and uc patients was integrity, a few lymphocyte and plasma cell infiltration could be seen in submucosa and intrinsic glands, the differences were not significant as compared with the controls.
2.1 expressions of ifnγ and il2
ifnγ and il2 expressed in lamina propria of the rectal mucosa, appearing as buffy in color, and distributing around the glands. the respective positive expression rates of ifnγ and il2 of piibs were 80.7% and 69.2%; of uc were 84.4% and 82.2%; of controls were 26.6% and 20.0%. the positive expressions of ifnγ and il2 in piibs were higher than those of the controls (χ2=14.012,13.931;p<0.01), but there were no significant differences compared with uc (χ2=2.290,2.323;p>0.05）.
2.2 expression of sp
sp was expressed in the propria around the glands, in the form of scattering points or clusters. the intensity of sp in rectal mucosa of piibs, uc and controls was 13.8±2.5, 15.0±2.6 and 8.8±2.0, respectively, which was higher in piibs than that of the controls (t=3.722,p<0.01), but no significant difference as compared with uc (t=1.643,p>0.05). sp intensity in uc was higher than that of the controls (t=4.524,p<0.01).
in piibs with positive rectalmucosa il2 and ifnγ, the intensity of sp was 14.5±3.0 and 15.0±3.2; in uc, it was 16.9±3.8 and 16.8±3.9; and in the controls, it was 9.9±2.2 and 10.8±3.2, respectively, which was higher in piibs than that in the controls (t=2.301, 2.252;p<0.05), but the difference between piibs and uc did not reach statistical significance (t=1.574,1.676;p>0.05）.
3 discussion
ibs differs from ibd. recent studies, however, indicate that they have many similarities in symptoms and mechanisms, and the risk of ibs developing into ibd increases. bercik p et al[6] proposed that ibs may be the lower grade of ibd. the occurrence of ibs and ibd and exacerbation of their symptoms are probably associated with bowel infection. flectobacillus and bacillus coli, and others, are important factors making symptoms more serious. there are similarities in inflammation/immunity between them. th1/th2 cytokines disbalance[7], and tleukomonocyte miopragia and maladjustment[8] exist in bowel mucosa of patients with ibs or ibd. slight antiinflammatory factors can be easily produced in the rectal mucosa of ibs, which is similar to ibd. there are abnormalities of intestinal immue system and immunocyte in both ibs and ibd.
it was found in the present study that the expressions of il2 and ifnγ in rectal mucosa in piibs and uc were higher than that in the controls, which is similar to the report of li yanqing et al[5]. il2 and ifnγ are th1 cytokines, both of them can facilitate the expressions of histamine, arachidonic acid metabolic products (pgd2, ltc4, ltd4, txe4) and platelet activating factor (paf), the contraction of colon smooth muscles, the peristalsis of intestinal tract, and vasopermeability, resulting in diarrhea[9]. the increased expressions of il2 and ifnγ can destroy the mucosa epithelium barrier, augment the vasopermeability and cause water and sodium malabsorption to cause diarrhea. it is presumed that the increased expressions of ifnγ and il2 in rectal mucosa in piibs and uc are likely related to infection, as infection is an important cause leading to occurrence and aggravation of symptoms in ibs and ibd. some enteroinfecting pathogens directly destroy intestinal mucosal barrier or destroy the int tinal mucosa through endotoxin or cytokines, i.e., tnfα, ifnγ and il2. a low grade inflammation lasting after acute gastroenteritis can destroy the intestinalmucosa epithelium barrier and provoke overexposure of antigens and absence of brush border, which will activate the intestinalmucosa immune system, resulting in the increase of mast cells, lymphocytes, and endocrine cells and the release of various cytokines[10]. the changes in the internal environment of the enteric cavity, especially the changes of microbial population, can augment the intestine permeability and influence mucosa immune system through the antigen stimulation, which play a grave role of inflammation of intestinal tract in uc.
studies indicate that there are similar mucosaneuromechanism changes in ibs and uc[11]. the expression of sp increases obviously in ibs rectal mucosa. sp, a major sensory neuropeptide promoting inflammation, can affect sigmoid colon smooth muscles by circulating hormonal action and reinforce the movement leading to diarrhea. sp can promote the colon to peristalsis by transmitting to noncholinergic nerve, promote the no synthesis and vasopermeability by activating endotheliocyte calciumiondependent no, and to increase the transportation of the mucosa ions by stimulating mucosa secreting motor nerves to lead to diarrhea. the increased expression of sp in diarrheaibs rectal mucosa may be related to colon hyperkinesis and mucus secreting increase leading to diarrhea.
it is believed that interactions exist between intestinalmucosa immune system and afferent nerve ending. the correlativity of the positive expressions of inflammatory cytokines (il2 and ifnγ) and the expression of sp in the rectal mucosa were then analyzed, the difference was not statistically significant as compared with uc. it is supposed that the expressions of sp, il2 and ifnγ are related with infection, and infection may lead to the increased expression of sp, which combines with spreceptors (mainly neurokinin1, nk1)on the surface of inflammatory cells to promote th1 cells to release ifnγ, il2 and il12 and induce th1 type reaction to release inflammatory factors, such as il1β, tnfα and pge2, to destroy the function of intestinalmucosa epithelium barrier[12], and thus ibslike symptoms appear.
by analyzing the expressions of sp, ifnγ and il2 in rectal mucosa of piibs and uc patients in remission, the differences noted of the above expressions between piibs and uc were not statistically significant. it is thought that some correlation exists between ibs and ibd based on neuroimmunologicmechanism analysis, which supports the standpoint that ibs can be a low grade of ibd.
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