Up-regulation of Annexin-A1 and Lipoxin A(4) in Individuals With Ulcerative Colitis May Promote Mucosal Homeostasis

PLoS One. 2012;7(6):e39244. doi: 10.1371/journal.pone.0039244. Epub 2012 Jun 18.

Abstract

Background: One of the characteristics of an active episode of ulcerative colitis (UC) is the intense mucosal infiltration of leukocytes. The pro-resolution mediators Annexin-A1 (AnxA1) and lipoxin A(4) (LXA(4)) exert counter-regulatory effects on leukocyte recruitment, however to date, the dual/cumulative effects of these formyl peptide receptor-2 (FPR2/ALX) agonists in the context of human intestinal diseases are unclear. To define the contribution of these mediators, we measured their expression in biopsies from individuals with UC.

Methods: Colonic mucosal biopsies were collected from two broad patient groups: healthy volunteers without ('Ctrl' n = 20) or with a prior history of UC ('hx of UC' n = 5); individuals with UC experiencing active disease ('active' n = 8), or in medically-induced remission ('remission' n = 16). We assessed the mucosal expression of LXA(4), AnxA1, and the FPR2/ALX receptor in each patient group using a combination of fluorescence microscopy, biochemical and molecular analyses.

Results: Mucosal expression of LXA(4) was elevated exclusively in biopsies from individuals in remission (3-fold, P<0.05 vs. Ctrl). Moreover, in this same group we observed an upregulation of AnxA1 protein expression (2.5-fold increase vs. Ctrl, P<.01), concurrent with an increased level of macrophage infiltration, and an elevation in FPR2/ALX mRNA (7-fold increase vs. Ctrl, P<.05). Importantly, AnxA1 expression was not limited to cells infiltrating the lamina propria but was also detected in epithelial cells lining the intestinal crypts.

Conclusions: Our results demonstrate a specific up-regulation of this pro-resolution circuit in individuals in remission from UC, and suggest a significant role for LXA(4) and AnxA1 in promoting mucosal homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Annexin A1 / genetics
  • Annexin A1 / metabolism*
  • Colitis, Ulcerative / genetics
  • Colitis, Ulcerative / metabolism*
  • Colon / metabolism
  • Colon / pathology
  • Cyclooxygenase 2 / metabolism
  • Cytokines / metabolism
  • Female
  • Granulocytes / immunology
  • Granulocytes / pathology
  • Homeostasis / genetics*
  • Humans
  • Inflammation Mediators / metabolism
  • Intestinal Mucosa / metabolism*
  • Lipoxins / genetics
  • Lipoxins / metabolism*
  • Macrophages / immunology
  • Macrophages / pathology
  • Male
  • Middle Aged
  • Receptors, Formyl Peptide / genetics
  • Receptors, Formyl Peptide / metabolism
  • Receptors, Lipoxin / genetics
  • Receptors, Lipoxin / metabolism
  • Up-Regulation / genetics

Substances

  • Annexin A1
  • Cytokines
  • FPR2 protein, human
  • Inflammation Mediators
  • Lipoxins
  • Receptors, Formyl Peptide
  • Receptors, Lipoxin
  • lipoxin A4
  • Cyclooxygenase 2