Division of Pediatric Gastroenterology, USA.
J Pediatr Gastroenterol Nutr. 2011 Feb;52(2):140-6. doi: 10.1097/MPG.0b013e3182039bad.
CD40, a co-stimulatory molecule, plays a critical role in coordinating enteric inflammatory immune responses. In necrotizing enterocolitis (NEC), upregulation of IL-10, a CD40-modulated cytokine, has been described, but the role of the IL-10 receptor (IL-10Rβ), CD40, and its ligand CD40L in disease pathogenesis is unknown. The study herein investigates ileal expression of CD40, CD40L, and IL-10R in a rat model of NEC.
NEC was induced in newborn rats using established methods of formula feeding, asphyxia, and cold stress. Expression of CD40, CD40L, IL-10Rβ, and other proinflammatory molecules, including Toll-like receptor-4 (TLR-4) and IL-18, was assessed by immunoblotting. Tissue infiltration by macrophages, monocytes, and T cells was examined by confocal immunohistochemistry.
Ileum from rat pups with NEC showed increased expression of TLR-4, IL-18, and IL-10Rβ. Sections from both NEC and control pups demonstrated preservation of ileal cells expressing CD40/CD40L. The distal ileum of controls expressed both CD40 and CD40L; conversely, neither molecule was detected in ileal tissue from NEC pups. Additional studies showed that treatment with epidermal growth factor (EGF), previously shown to ameliorate the severity of NEC in an animal model, did not restore CD40 expression.
Ileal cytokine dysregulation, manifested by decreased CD40/CD40L and increased IL-10Rβ expression, may be involved in the pathogenesis of NEC. Dampened CD40 signaling may be related to enhanced IL-10 expression and a suppressed T-cell response to injury. We speculate that augmenting CD40-CD40L interactions may achieve a protective effect in this NEC model.
CD40 是一种共刺激分子，在协调肠道炎症免疫反应中发挥关键作用。在坏死性小肠结肠炎（NEC）中，已描述了 IL-10（一种受 CD40 调节的细胞因子）的上调，但 IL-10 受体（IL-10Rβ）、CD40 及其配体 CD40L 在疾病发病机制中的作用尚不清楚。本研究旨在调查 NEC 大鼠模型中回肠 CD40、CD40L 和 IL-10R 的表达。
采用配方喂养、窒息和冷应激建立的新生大鼠 NEC 模型，通过免疫印迹法评估 CD40、CD40L、IL-10Rβ 及其他促炎分子，包括 Toll 样受体-4（TLR-4）和 IL-18 的表达。通过共聚焦免疫组织化学检测巨噬细胞、单核细胞和 T 细胞的组织浸润。
NEC 大鼠回肠 TLR-4、IL-18 和 IL-10Rβ 的表达增加。NEC 和对照组大鼠的回肠组织均保留了表达 CD40/CD40L 的回肠细胞。对照组大鼠的远端回肠均表达 CD40 和 CD40L；相反，NEC 大鼠的回肠组织均未检测到这两种分子。进一步的研究表明，表皮生长因子（EGF）治疗，先前已显示在动物模型中改善 NEC 的严重程度，但不能恢复 CD40 的表达。
回肠细胞因子失调，表现为 CD40/CD40L 表达减少和 IL-10Rβ 表达增加，可能与 NEC 的发病机制有关。CD40 信号减弱可能与 IL-10 表达增强和 T 细胞对损伤的反应抑制有关。我们推测，增强 CD40-CD40L 相互作用可能在这种 NEC 模型中产生保护作用。
