2nd Annual BMRP Investigator Meeting - Abstract
LFA-1 Deficient T-Cells Fail to Induce Chronic Colitis in an Immune-Based Mouse Model
Kevin P. Pavlick, Dmitry Ostanin and Matthew B. Grishama
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center (Shreveport, U.S.A.)
Background: Interaction of the integrin aLb2 (CD11a/CD18 or LFA-1) with its ligands intracellular adhesion molecule (ICAM-1 or -2) is important for lymphocyte homing as well as lymphocyte activation. The objective of this study was to assess the role of T cell-associated LFA-1 in initiating and/or perpetuating chronic colitis in vivo.
Methods: Transfer of CD4+CD45RBhigh T-cells isolated from either wild type (wt) or CD11a (aL) deficient (LFA-1-/-) C57Bl/6 mice, into Recombinase Activating Gene-1-deficient (RAG-1-/-) C57Bl/6 recipients was used to induce chronic colitis. Blinded histopathology and differences in colon weight/length ratios were used to quantify colonic inflammation. Cytokine protein levels produced by lamina propria lymphocytes (LPLs) were quantified using cytometric bead array.
Results: At 8-10 weeks following T-cell transfer, we observed a significant decrease in colon weight/length ratios in LFA-1-/- injected mice compared to wt T-cell injected colitic mice (4.08 ± 0.42 vs. 6.64 ± 0.64, respectively; p=0.007). This apparent decrease in colonic inflammation was confirmed by blinded histopathological scoring (14 ± 2.53 vs. 1.86 ± 0.36 for wt vs. LFA-1-/- T-cell injected mice, respectively; p=0.008). In addition, the number of colonic IELs and LPLs from LFA-1-/- injected mice was reduced by 11- and 5-fold, respectively. Isolated colonic LPLs from RAG-1 mice (injected with wt CD4+CD45RBhigh T-cells) and stimulated with CD3/CD28 antibodies expressed large amounts of TNF-a and IFN-a (3.23 and 3.55 ng/ml, respectively), whereas LPLs from RAG-1-/- reconstituted with LFA-1-/- CD4+CD45Rbhigh T-cells produced 3-fold less protein levels of these two cytokines (1.18 and 1.02 ng/ml, respectively).
Conclusion: LFA-1 deficiency on T-cells attenuates chronic colitis in an immune-based model that is associated with a decrease in colonic CD3+CD4+ lymphocytes in the IEL and LPL compartments. Additionally, the capacity for LFA-1-/- colonic LPLs to produce inflammatory cytokines is reduced. Taken together, these data suggest that LFA-1 is critical for T-cell activation, polarization, and/or recruitment into the colonic interstitium where they induce chronic colitis.
aPrincipal Investigator