炎症性腸疾患の治療ターゲットとしての病理組織学的所見の位置付け

Pathological Findings as a Potential Therapeutic Target for Inflammatory Bowel Disease

要旨●潰瘍性大腸炎には内視鏡的に寛解期と判定されても組織学的には活動性のものが多く含まれており，活動性評価には組織学的評価が必須である．単に活動性の評価だけでなく，難治化や再燃の予測と関連した組織学的評価法の確立が重要である．これまでの報告からは組織学的粘膜治癒の定義としては，少なくともIOIBDが提唱した3項目（①好中球の消失，②basal plasmacytosisの消失と正常範囲の形質細胞数，③正常範囲の好酸球数）を満たすことが必要条件で，より厳密な“complete normalization”が理想的である．また，難治化や再燃の予測に関係する組織学的因子として，好中球浸潤（間質と上皮内），陰窩膿瘍，好酸球浸潤，粘液減少，basal plasmacytosis，腺管構造不整，表層上皮破壊が報告されているが，これらの総合的な評価では不十分である．治療法選択に意義のある組織学的因子の抽出と評価基準の確立が今後の課題である．

　Histological evaluation of disease activity in ulcerative colitis is indispensable, even if it is determined to be in endoscopic remission, because many cases remain histologically active. Thus, it is important to establish a histological evaluation method that can not only evaluate disease activity but also predict the risk of intractability and relapse. The definition of histological mucosal healing as proposed by the IOIBD, based on the reports so far, requires, at minimum, the following three factors：①the disappearance of neutrophils, ②disappearance of basal plasmacytosis and normal range of plasma cells, and ③presence of a normal range of eosinophils ; however, a more rigorous “complete normalization” is deemed ideal. Although histological factors associated with predicting intractability and relapse have been reported, such as neutrophil and eosinophil infiltration（interstitial and intraepithelial）, crypt abscesses, mucilage reduction, basal plasmacytosis, ductal abnormalities, as well as surface epithelial destruction, their overall assessment remains inadequate. Hence, identification of histological factors that are meaningful for treatment selection and establishment of evaluation criteria is needed.