Microflora reactive IL-10 producing regulatory T cells are present in the colon of IL-2 deficient mice but lack efficacious inhibition of IFN-gamma and TNF-alpha production.
BACKGROUND
Inflammatory bowel disease in interleukin 2 (IL-2) deficient (IL-2(-/-)) mice is triggered by the intestinal microflora and mediated by CD4(+) T cells.


OBJECTIVE
To determine the characteristics of microflora specific intestinal T cells, including migration and cytokine production.


METHODS
Intestinal T cell populations and cytokine mRNA expression of specific pathogen free (SPF) and germ free (GF) IL-2(-/-) and IL-2(+/+) mice were compared by flow cytometry and reverse transcription-polymerase chain reaction. Cytokine production of intestinal mononuclear cells on stimulation with microflora antigens was assessed by ELISA. In vivo migration of T cells was assessed by adoptive transfer of (51)Cr labelled CD4(+)CD25(-)alpha beta(+) T cells. The ability of intestinal T cell lines to promote colitis was determined by adoptive transfer experiments.


RESULTS
SPF IL-2(-/-) mice produced higher interferon gamma (IFN-gamma) and tumour necrosis factor alpha mRNA levels than GF IL-2(-/-) mice, which was accompanied by an increased number of CD4(+)alpha beta T cells in the colon. Tracking of (51)Cr labelled and adoptively transferred T cells revealed an increased MAdCAM-1 dependent but VCAM-1 independent recruitment of these cells into the colon of SPF IL-2(-/-) mice. Colon lamina propria lymphocytes (LPL) from SPF IL-2(-/-) mice showed increased spontaneous IFN-gamma production in vitro. On stimulation with bacterial microflora antigens, intraepithelial lymphocytes and LPL did not produce IFN-gamma, but high quantities of IL-10, which did not suppress IFN-gamma production. Bacterial antigen specific cell lines established from colon LPL of SPF IL-2(-/-) mice with colitis showed a regulatory T cell-like cytokine profile and only marginally modulated the course of colitis and survival of IL-2(-/-) mice.


CONCLUSIONS
Our results suggest that microflora reactive regulatory T cells are present in the colon of SPF IL-2(-/-) mice. However, IL-10 produced by these cells did not significantly modulate a possible secondary proinflammatory CD4 Th1 cell population to produce IFN-gamma.
Waidmann
M
M
Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Universität München, Pettenkofer Strasse 9a, 80336 München, Germany.
Allemand
Y
Y
Lehmann
J
J
di Genaro
S
S
Bücheler
N
N
Hamann
A
A
Autenrieth
I B
IB
D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D001439:Bacteroides / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000382:microbiology*; D015815:Cell Adhesion Molecules; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D003092:Colitis / Q000378:metabolism / Q000382:microbiology; D003106:Colon / Q000378:metabolism / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D007136:Immunoglobulins / Q000502:physiology; D007371:Interferon-gamma / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism*; D007376:Interleukin-2 / Q000172:deficiency*; D051379:Mice; D008810:Mice, Inbred C57BL; D009088:Mucoproteins / Q000502:physiology; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000942:Antigens, Bacterial; D015815:Cell Adhesion Molecules; D007136:Immunoglobulins; D007376:Interleukin-2; C489082:Madcam1 protein, mouse; D009088:Mucoproteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D007371:Interferon-gamma