T follicular helper (Tfh) cells represent a novel subset of CD4⁺ T cells which can provide critical help for germinal center (GC) formation and antibody production. The Tfh cells are characterized by the expression of CXC chemokine receptor 5 (CXCR5), programmed death 1 (PD-1), inducible costimulatory molecule (ICOS), B cell lymphoma 6 (BCL-6), and the secretion of interleukin-21 (IL-21). Given the important role of Tfh cells in B cell activation and high-affinity antibody production, Tfh cells are involved in the pathogenesis of many human diseases. Inflammatory bowel disease (IBD) is a group of chronic inflammatory diseases characterized by symptoms such as diarrhea, abdominal pain, and weight loss. Ulcerative colitis (UC) and Crohn’s disease (CD) are the most studied types of IBD. Dysregulated mucosal immune response plays an important role in the pathogenesis of IBD. In recent years, many studies have identified the critical role of Tfh cells and IL-21 in the pathogenic process IBD. In this paper, we will discuss the role of Tfh cells and IL-21 in IBD pathogenesis.

中文翻译：

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T 滤泡辅助细胞和白细胞介素 21 在炎症性肠病发病机制中的作用

T 滤泡辅助 (Tfh) 细胞代表 CD4 ^{+ 的}一个新子集T 细胞可以为生发中心 (GC) 的形成和抗体的产生提供关键帮助。Tfh 细胞的特征在于表达 CXC 趋化因子受体 5 (CXCR5)、程序性死亡 1 (PD-1)、诱导型共刺激分子 (ICOS)、B 细胞淋巴瘤 6 (BCL-6) 和白细胞介素 21 的分泌(IL-21)。鉴于 Tfh 细胞在 B 细胞活化和高亲和力抗体产生中的重要作用，Tfh 细胞参与了许多人类疾病的发病机制。炎症性肠病（IBD）是一组以腹泻、腹痛和体重减轻等症状为特征的慢性炎症性疾病。溃疡性结肠炎 (UC) 和克罗恩病 (CD) 是研究最多的 IBD 类型。失调的粘膜免疫反应在 IBD 的发病机制中起重要作用。最近几年，许多研究已经确定了 Tfh 细胞和 IL-21 在 IBD 致病过程中的关键作用。在本文中，我们将讨论 Tfh 细胞和 IL-21 在 IBD 发病机制中的作用。