Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, also known as disorders of the gut–brain interaction; however, the pathophysiology of IBS remains unclear. Early life stress (ELS) is one of the most common risk factors for IBS development. However, the molecular mechanisms by which ELS induces IBS remain unclear. Enterochromaffin cells (ECs), as a prime source of peripheral serotonin (5-HT), play a pivotal role in intestinal motility, secretion, proinflammatory and anti-inflammatory effects, and visceral sensation. ECs can sense various stimuli and microbiota metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids. ECs can sense the luminal environment and transmit signals to the brain via exogenous vagal and spinal nerve afferents. Increasing evidence suggests that an ECs-5-HT signaling imbalance plays a crucial role in the pathogenesis of ELS-induced IBS. A recent study using a maternal separation (MS) animal model mimicking ELS showed that MS induced expansion of intestinal stem cells and their differentiation toward secretory lineages, including ECs, leading to ECs hyperplasia, increased 5-HT production, and visceral hyperalgesia. This suggests that ELS-induced IBS may be associated with increased ECs-5-HT signaling. Furthermore, ECs are closely related to corticotropin-releasing hormone, mast cells, neuron growth factor, bile acids, and SCFAs, all of which contribute to the pathogenesis of IBS. Collectively, ECs may play a role in the pathogenesis of ELS-induced IBS. Therefore, this review summarizes the physiological function of ECs and focuses on their potential role in the pathogenesis of IBS based on clinical and pre-clinical evidence.

Kawasaki disease (KD) is an acute febrile multisystem vasculitis and has been recognized to be one of the most common causes of acquired heart disease in children. Although gastrointestinal symptoms including vomiting, diarrhea, and abdominal pain are not uncommon in KD patients, KD with lower gastrointestinal bleeding is quite rare. Here, we describe a 3-year-old boy with typical KD who had lower gastrointestinal bleeding caused by rectal ulcers on the third day of aspirin therapy.

Background Kawasaki disease (KD) is an acute febrile multisystem vasculitis and has been recognized to be the most common cause of acquired heart disease in children. Owing to its propensity to involve vessels throughout the entire body, KD often mimics other disease processes. The diagnosis might be delayed if other prominent symptoms appear before the characteristic clinical features of KD. Although gastrointestinal symptoms including vomiting, diarrhea, and abdominal pain are not uncommon in KD patients, KD with gastrointestinal bleeding is quite rare. Case presentation A previously healthy 4-year-old boy initially presented with abdominal pain, followed by fever, rash, and gastrointestinal hemorrhage, eventually diagnosed as complete KD. The patient recovered smoothly after appropriate management and no subsequent complications occurred in the following months. Conclusion The diagnosis of KD should be considered in children presenting with abdominal symptoms and fever without definable cause. Pediatricians should be aware of the risk of gastrointestinal bleeding in patients with KD, especially in those with prominent abdominal symptoms.