A new model of chronic colitis in SCID mice induced by adoptive transfer of CD62L+ CD4+ T cells: insights into the regulatory role of interleukin-6 on apoptosis.
OBJECTIVE
The proinflammatory cytokine interleukin (IL)-6 is involved in various chronic inflammatory processes. IL-6 is a predominant cytokine produced by lamina propria T cells in Crohn's disease and experimental colitis. This study was designed to examine the effect of a neutralizing IL-6-receptor (IL-6R) antibody on the programmed cell death of mucosal T cells in the CD62L+ CD4+ SCID transfer model of chronic experimental colitis in mice and to gain more insight into the pathogenesis of this transfer colitis model.


METHODS
For adoptive transfer, we isolated CD62L+ CD4+ double-positive T cells from wild-type BALB/c mice followed by intraperitoneal application of 1 million cells in CB17 SCID mice. The purity of the transferred T-cell population was tested by FACS analysis. Cytokine secretion was measured by ELISA. Western blot analysis was performed to detect phospho-STAT-3 in protein extracts of splenic cells. Cryo- and paraffin colon cross-sections were used to perform immunochemical or fluorescence TUNEL stainings.


RESULTS
We isolated CD62L+ CD4+ and CD62L- CD4+ T cells. In vitro studies showed an increased production of IL-4 by CD62L- CD4+ T cells compared to CD62L+ T cells. 8-10 weeks after transfer of CD62L+ CD4+ T cells in SCID mice, reconstituted mice developed wasting disease, anal prolapse and diarrhea, whereas mice reconstituted with CD62L- CD4+ did not, similar to anti-IL-6R-treated CD62L+ CD4+-reconstituted SCID mice. Anti-IL-6R-treated reconstituted SCID mice showed decreased levels of activated STAT-3. The previously described efficacy of anti-IL-6R antibody treatment on colitis activity appeared to be due to the induction of apoptosis, as many TUNEL-positive cells were detected in the lamina propria.


CONCLUSIONS
These results suggest that the activation of the IL-6/STAT-3-signaling pathway plays a pivotal role in the pathogenesis of CD62L+ CD4+ transfer colitis. Moreover, the application of a neutralizing antibody to IL-6R induces apoptosis in transferred T cells. These data implicate the importance of anti-apoptotic pathways in chronic disease and might contribute to future therapies.
Mudter
Jonas
J
1st Medical Clinic, Johannes Gutenberg University of Mainz, Mainz, Germany. jmudter@gmx.de
Wirtz
Stefan
S
Galle
Peter R
PR
Neurath
Markus F
MF
D019264:Adoptive Transfer; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D017690:Cell Transplantation; D003093:Colitis, Ulcerative / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004195:Disease Models, Animal; D005434:Flow Cytometry; D020287:In Situ Nick-End Labeling; D015850:Interleukin-6 / Q000276:immunology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D019041:L-Selectin / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D019947:Receptors, Interleukin-6 / Q000276:immunology; D050796:STAT3 Transcription Factor; D016511:Severe Combined Immunodeficiency / Q000235:genetics / Q000276:immunology; D013154:Spleen / Q000378:metabolism / Q000473:pathology; D015534:Trans-Activators / Q000096:biosynthesis
D019138:Antibodies, Blocking; D004268:DNA-Binding Proteins; D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D019041:L-Selectin