Appropriateness of recommendations for surveillance colonoscopy after polypectomy - a comparison of adherence to the 2012 and 2020 USMSTF guidelines.

Background: Screening colonoscopy detects precancerous polyps, which when resected, prevents colon cancer. Recommendations for surveillance colonoscopy after polypectomy are based on the U.S. Multi-Society Task Force guidelines (USMSTF). Aim: to examine provider recommendations based on 2012 and 2020 USMSTF guidelines. Methods: A prospective analysis was performed to examine provider recommendations for index screening and surveillance colonoscopy from March 2022 to January 2023. Procedures with unknown histology or unsatisfactory bowel preparation were excluded. We recorded polyp morphology, histology, and subsequent recommendations made by endoscopists, to compare to the USMSTF guidelines. Results: 241 patients were included, with 371 endoscopies reviewed. For index screening colonoscopies, 86%, performed between 2012 and 2020, adhered to 2012 guidelines, while 71%, performed after 2020, adhered to the 2020 guidelines. For surveillance colonoscopies, 62% from 2012 and 2020, and 50% after 2020, adhered to the 2012 and 2020 guidelines, respectively (P < 0.001). For polyp types, recommendations after index colonoscopies showed low-risk adenoma (LRA) had 88% adherence to 2012 guidelines versus 73% adherence to 2020 guidelines. For surveillance colonoscopies, LRA had 73% adherence to 2012 guidelines versus 42% adherence to 2020 guidelines (P < 0.001). Recommendations after index colonoscopy showed high-risk adenoma (HRA) had 79% adherence to 2012 guidelines versus 63% adherence to 2020 guidelines. For surveillance colonoscopies, HRA had 88% adherence to the 2012 guidelines versus 69% adherence to 2020 guidelines (P < 0.001). Conclusions: Adherence declined for the introduction of 2020 guidelines and was poorer after 2nd surveillance exams. Increasing the evidence for interval recommendations may increase guideline adherence.

Langerhans Cells Prevent Autoimmunity via Expansion of Keratinocyte Antigen-Specific Regulatory T Cells.

Langerhans cells (LCs) are antigen-presenting cells in the epidermis whose roles in antigen-specific immune regulation remain incompletely understood. Desmoglein 3 (Dsg3) is a keratinocyte cell-cell adhesion molecule critical for epidermal integrity and an autoantigen in the autoimmune blistering disease pemphigus. Although antibody-mediated disease mechanisms in pemphigus are extensively characterized, the T cell aspect of this autoimmune disease still remains poorly understood. Herein, we utilized a mouse model of CD4+ T cell-mediated autoimmunity against Dsg3 to show that acquisition of Dsg3 and subsequent presentation to T cells by LCs depended on the C-type lectin langerin. The lack of LCs led to enhanced autoimmunity with impaired Dsg3-specific regulatory T cell expansion. LCs expressed the IL-2 receptor complex and the disruption of IL-2 signaling in LCs attenuated LC-mediated regulatory T cell expansion in vitro, demonstrating that direct IL-2 signaling shapes LC function. These data establish that LCs mediate peripheral tolerance against an epidermal autoantigen and point to langerin and IL-2 signaling pathways as attractive targets for achieving tolerogenic responses particularly in autoimmune blistering diseases such as pemphigus.