NSAIDs disrupt intestinal homeostasis by suppressing macroautophagy in intestinal epithelial cells

Small intestinal damage induced by nonsteroidal anti-inflammatory drugs (NSAIDs) remains an under-recognized clinical disorder. The incomplete understanding of the pathophysiology has hampered the development of prevention and treatment strategies leading to the high morbidity and mortality rates. NSAIDs are known to modulate macroautophagy, a process indispensable for intestinal homeostasis. Whether NSAIDs stimulate or repress macroautophagy and how this correlates with the clinical manifestations of NSAID enteropathy, however, remains unknown. The objectives of this study were to determine whether NSAIDs impaired macroautophagy and how this affects macroautophagy-regulated intestinal epithelial cell (IEC) processes essential for intestinal homeostasis (i.e., clearance of invading pathogens, secretion and composition of mucus building blocks, and inflammatory response). We show that NSAID treatment of IECs inhibits macroautophagy in vitro and in vivo. This inhibition was likely attributed to a reduction in the area and/or distribution of lysosomes available for degradation of macroautophagy-targeted cargo. Importantly, IEC regulatory processes necessary for intestinal homeostasis and dependent on macroautophagy were dysfunctional in the presence of NSAIDs. Since macroautophagy is essential for gastrointestinal health, NSAID-induced inhibition of macroautophagy might contribute to the severity of intestinal injury by compromising the integrity of the mucosal barrier, preventing the clearance of invading microbes, and exacerbating the inflammatory response.