Ohman L, Lindmark A-C, Isaksson S, Posserud I, Strid H, Sjövall H, Simrén M
Institute of Medicine, The Sahlgren's Academy, University of Gothenburg, Sweden.
Neurogastroenterol Motil. 2009 Jun;21(6):644-50, e27. doi: 10.1111/j.1365-2982.2009.01272.x. Epub 2009 Feb 14.
Patients with irritable bowel syndrome (IBS) may have a low grade immune activation. However, little is known about the properties of B cells of IBS patients. We therefore investigated activation level and antigen presenting phenotype of blood B cells of IBS patients. We also examined B-cell responses to lipopolysaccharide (LPS) and probiotic bacteria. Blood samples were obtained from 74 IBS patients and 30 healthy subjects. Peripheral blood mononuclear cells were isolated and stimulated with LPS or an UV-light inactivated bacterial cocktail consisting of the probiotic Gram-positive strains; Lactobacillus paracasei ssp. paracasei 19, Lactobacillus acidophilus La5, Bifidobacterium lactis B612. The phenotype of CD19(+) B cells was investigated by flow cytometry before and after 72 h cell culture. Furthermore, IBS symptom severity was assessed. B cells isolated from blood of IBS patients displayed an amplified activation level as demonstrated by increased cell surface expression of IgG, and also the costimulatory molecules CD80 and CD86. Expression of antigen presenting HLA-DR and costimulatory molecule CD40 on B cells was, however comparable in IBS patients and controls. B cells of IBS patients displayed an impaired ability to increase expression of CD80, but not CD86, in response to both LPS as well as probiotic bacteria stimulations. To conclude, blood B cells of IBS patients have an increased activation level. Bacterial component induced expression of the costimulatory molecule CD80, regarded as important for tolerance induction, is impaired. These data suggest that B-cell antigen presentation in IBS patients is associated with altered capacity of providing costimulation to T cells.
肠易激综合征（IBS）患者可能存在低度免疫激活。然而，关于IBS患者B细胞的特性知之甚少。因此，我们研究了IBS患者血液B细胞的激活水平和抗原呈递表型。我们还检测了B细胞对脂多糖（LPS）和益生菌的反应。从74例IBS患者和30名健康受试者采集血样。分离外周血单个核细胞，并用LPS或由益生菌革兰氏阳性菌株组成的紫外线灭活细菌混合物刺激；副干酪乳杆菌副干酪亚种19、嗜酸乳杆菌La5、双歧杆菌B612。在细胞培养72小时前后，通过流式细胞术研究CD19(+) B细胞的表型。此外，评估IBS症状的严重程度。从IBS患者血液中分离的B细胞显示出激活水平增强，表现为IgG以及共刺激分子CD80和CD86的细胞表面表达增加。然而，IBS患者和对照组B细胞上抗原呈递HLA-DR和共刺激分子CD40的表达相当。IBS患者的B细胞在对LPS和益生菌刺激的反应中，增加CD80表达的能力受损，但CD86不受影响。总之，IBS患者的血液B细胞激活水平增加。被认为对诱导耐受性很重要的共刺激分子CD80的细菌成分诱导表达受损。这些数据表明，IBS患者的B细胞抗原呈递与向T细胞提供共刺激的能力改变有关。
