Biomedical Research Institute of New Mexico, VA Health Care System, Albuquerque, New Mexico, USA, 87108.
Department of Anatomy & Neuroscience, University College Cork; APC Microbiome institute, University College Cork, Cork, Ireland.
Sci Rep. 2020 Feb 20;10(1):3107. doi: 10.1038/s41598-020-59474-6.
Intestinal alkaline phosphatase (IAP) regulates bicarbonate secretion, detoxifies lipopolysaccharide (LPS), regulates gut microbes, and dephosphorylates proinflammatory nucleotides. IAP also exhibits anti-inflammatory effects in a Toll-like Receptor-4 (TLR-4) dependent manner. However, it is not known whether IAP induces autophagy. We tested the hypothesis that IAP may induce autophagy which may mediate the anti-inflammatory effects of IAP. We found that exogenous IAP induced autophagy in intestinal epithelial cells and in macrophages. TLR4INC34 (C34), a TLR4 signaling inhibitor, suppressed IAP-induced autophagy. IAP also inhibited LPS-induced IL-1β mRNA expression and activation of NF-κB. When autophagy was blocked by 3-methyladenine (3MA) or by Atg5 siRNA, IAP failed to block LPS-mediated effects. IAP also upregulated autophagy-related gene expression in small intestine in mice. We administered either vehicle or IAP (100 U/ml) in drinking water for 14 days in C57BL/6 mice. Mice were sacrificed and ileal tissues collected. Increased expression of Atg5, Atg16, Irgm1, Tlr4, and Lyz genes was observed in the IAP treated group compared to the vehicle treated group. Increase in Atg16 protein expression and fluorescence intensity of LC3 was also observed in IAP-treated tissues compared to the vehicle-treated tissues. Thus, our study lays the framework for investigating how IAP and autophagy may act together to control inflammatory conditions.
肠碱性磷酸酶（IAP）调节碳酸氢盐分泌、解毒脂多糖（LPS）、调节肠道微生物群，并使促炎核苷酸去磷酸化。IAP 还以 Toll 样受体 4（TLR-4）依赖的方式表现出抗炎作用。然而，目前尚不清楚 IAP 是否诱导自噬。我们检验了这样一个假设，即 IAP 可能诱导自噬，而自噬可能介导 IAP 的抗炎作用。我们发现外源性 IAP 诱导肠上皮细胞和巨噬细胞发生自噬。TLR4 信号抑制剂 TLR4INC34（C34）抑制 IAP 诱导的自噬。IAP 还抑制 LPS 诱导的 IL-1β mRNA 表达和 NF-κB 激活。当自噬被 3-甲基腺嘌呤（3MA）或 Atg5 siRNA 阻断时，IAP 无法阻断 LPS 介导的作用。IAP 还在上皮细胞中上调了自噬相关基因的表达。我们在 C57BL/6 小鼠的饮用水中给予载体或 IAP（100 U/ml）14 天。处死小鼠并收集回肠组织。与载体处理组相比，IAP 处理组中 Atg5、Atg16、Irgm1、Tlr4 和 Lyz 基因的表达增加。与载体处理组相比，IAP 处理组的 Atg16 蛋白表达和 LC3 荧光强度也增加。因此，我们的研究为研究 IAP 和自噬如何共同控制炎症条件奠定了框架。
