Cryptosporidium uses CSpV1 to activate host type I interferon and attenuate antiparasitic defenses.

Cryptosporidium infects gastrointestinal epithelium and is a leading cause of infectious diarrhea and diarrheal-related death in children worldwide. There are no vaccines and no fully effective therapy available for the infection. Type II and III interferon (IFN) responses are important determinants of susceptibility to infection but the role for type I IFN response remains obscure. Cryptosporidium parvum virus 1 (CSpV1) is a double-stranded RNA (dsRNA) virus harbored by Cryptosporidium spp. Here we show that intestinal epithelial conditional Ifnar1-/- mice (deficient in type I IFN receptor) are resistant to C. parvum infection. CSpV1-dsRNAs are delivered into host cells and trigger type I IFN response in infected cells. Whereas C. parvum infection attenuates epithelial response to IFN-γ, loss of type I IFN signaling or inhibition of CSpV1-dsRNA delivery can restore IFN-γ-mediated protective response. Our findings demonstrate that type I IFN signaling in intestinal epithelial cells is detrimental to intestinal anti-C. parvum defense and Cryptosporidium uses CSpV1 to activate type I IFN signaling to evade epithelial antiparasitic response.

Recurrent Gastrointestinal Bleed Due to Small Bowel Vascular Malformation in a Patient with Turner Syndrome Diagnosed with Surgically Assisted Push Enteroscopy.

BACKGROUND Obscure gastrointestinal bleeding accounts for approximately 5% of all cases of gastrointestinal bleeding and the most frequent site is the small bowel. Turner syndrome (TS) is a genetic disorder of the second X chromosome in females. The association between gastrointestinal vascular malformations and Turner syndrome has been described in some case reports. Vascular malformation in Turner's syndrome can vary from asymptomatic to severe recurrent GI bleeds, but data on diagnosis and management of these patients are lacking. CASE REPORT A 14-year-old girl with TS presented with recurrent symptomatic melena. The initial work-up included a negative upper endoscopy, negative bidirectional endoscopies, and a video capsule endoscopy (VCE) that demonstrated large amount of blood and small erythematous lesion in the small bowel without active bleeding, and a negative Meckel scan. CT angiography was remarkable for prominent left lower mesenteric blood vessels, and a single-balloon enteroscopy demonstrated prominent vasculature throughout the small bowel. A a clip was placed at the site of a questionable bleed. The patient underwent a surgically assisted push enteroscopy due to recurrent bleeding; findings were consistent with diffuse vascular malformations. She was started on tranexamic acid and later transitioned to estrogen therapy without further reports of GI bleeding, anemia, or adverse effects from treatment 6 months after initial presentation. CONCLUSIONS Small bowel bleeding can be life-threating, and evidence-based guidelines in children are needed. Turner syndrome is associated with gastrointestinal vascular malformations, and suspicion for this diagnosis should be high for these patients when presenting with gastrointestinal bleeding. Estrogen might be an effective therapy in TS adolescent patients in the setting of diffuse vascular malformations (DVM).