C/EBPß Deletion Promotes Expansion of Poorly Functional Intestinal Regulatory T Cells.

BACKGROUND AND AIMS: Inflammatory Bowel Diseases [IBDs] are chronic intestinal inflammatory conditions in part mediated by CD4+ T cells. Anti-inflammatory Foxp3+ regulatory T cells [Tregs] maintain immune homeostasis and protect against IBD development via multiple mechanisms, including cytokine secretion and cell-cell interaction. CCAAT enhancer binding protein-beta [C/EBPß] is a stress-responsive transcription factor linked with IBD susceptibility. Whole-body C/EBPß deficiency induces CD4+ T cell-predominant hyperproliferation, and we hypothesize that this may be due to impaired Treg function. METHODS: We used the C/EBPß-/- mice in the CD45RBHigh adoptive transfer model, to assess C/EBPß-/- CD4+ T cells for their colitiogenic potential, and C/EBPß-/- CD4+ Foxp3+ Tregs for their ability to inhibit colitis. We assessed Tregs from the C/EBPß-/- mice for expression of Treg functional genes and proteins. RESULTS: Naïve C/EBPß-/- CD4+ T cells are more colitogenic in vivo. The exacerbated colitis does not appear to reflect impaired Treg development, however, as C/EBPß-/- mice displayed more, rather than fewer intestinal CD4+Foxp3+ Tregs in vivo. Instead, this reflects impaired Treg function as seen by the reduced capacity to suppress T cell proliferation in vitro, along with decreased secretion of the anti-inflammatory cytokine IL-10. These findings were corroborated in vivo by additional adoptive co-transfer studies in which wildtype Tregs prevented colitis but C/EBPß-/- Tregs did not. CONCLUSION: C/EBPß deficiency impairs Treg function and potentiates T cell-mediated colitis. A clearer understanding of the function of this transcription factor may provide a novel therapeutic strategy for IBD.

Pediatric Ulcerative Colitis: The Therapeutic Road to Infliximab.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that has significant morbidities in the pediatric population. Goals of medical therapy include induction and maintenance of remission while preserving the colon and it's function, while minimizing the risk of treatment related morbidities. For those children who do not respond to initial therapies and progress to develop moderately-to-severely active UC, there has been a dearth of available treatments to help induce remission, necessitating long-term corticosteroid usage, with associated comorbidities of chronic steroid treatment. Significant advances have been made in medical management, including the use of biologic therapies, specifically anti-tumor necrosis factor-α monoclonal antibodies. With the Food and Drug Administration's recent approval of the use of infliximab, a chimeric anti-tumor necrosis factor-α antibody, for children ≥6 years of age with moderately-to-severely active UC, care providers now have a new treatment regimen to offer this pediatric population.