Selective engraftment of memory CD4+ T cells with an unusual recirculation pattern and a diverse T cell receptor-V beta repertoire into scid mice

Xuebijing protects against lipopolysaccharide-induced lung injury in rabbits

Interleukin (IL)-23 has been identified as a member of the IL-12 cytokine family. It plays an important role in inflammation. To demonstrate the changes of IL-23 in acute lung injury (ALI) and investigate the protective effect of Xuebijing in ALI and the underlying molecular mechanism, ALI was induced by intravenous injection of lipopolysaccharide (LPS, 750 microg/kg). Japanese white rabbits challenged with or without LPS were treated with Xuebijing at the same time or saline. Before and after administration of LPS, arterial blood gas and lung weight gain were examined. Pathological changes of lung tissue were measured by light microscopy. IL-23 in serum was detected by enzyme-linked immunosorbent assay (ELISA). All animals demonstrated drops in arterial oxygen tension (Pao(2)) and oxygenation index (Pao(2)/Fio(2)) after LPS application, which were significantly reversed by Xuebijing treatment. Administration of Xuebijing reduced lung water gain. Histopathological study also indicated that Xuebijing treatment markedly attenuated lung histopathological changes, alveolar hemorrhage and inflammatory cells infiltration. Furthermore, IL-23 was higher than control group after LPS treatment, which could be blunted by Xuebijing. These findings confirmed significant protection by Xuebijing against LPS-induced lung vascular leak and inflammation and implicated inhibition of IL-23 expression a potential role for Xuebijing in the management of ALI.

IL-23 is essential for T cell-mediated colitis and promotes inflammation via IL-17 and IL-6

Uncontrolled mucosal immunity in the gastrointestinal tract of humans results in chronic inflammatory bowel disease (IBD), such as Crohn disease and ulcerative colitis. In early clinical trials as well as in animal models, IL-12 has been implicated as a major mediator of these diseases based on the ability of anti-p40 mAb treatment to reverse intestinal inflammation. The cytokine IL-23 shares the same p40 subunit with IL-12, and the anti-p40 mAbs used in human and mouse IBD studies neutralized the activities of both IL-12 and IL-23. IL-10-deficient mice spontaneously develop enterocolitis. To determine how IL-23 contributes to intestinal inflammation, we studied the disease susceptibility in the absence of either IL-23 or IL-12 in this model, as well as the ability of recombinant IL-23 to exacerbate IBD induced by T cell transfer. Our study shows that in these models, IL-23 is essential for manifestation of chronic intestinal inflammation, whereas IL-12 is not. A critical target of IL-23 is a unique subset of tissue-homing memory T cells, which are specifically activated by IL-23 to produce the proinflammatory mediators IL-17 and IL-6. This pathway may be responsible for chronic intestinal inflammation as well as other chronic autoimmune inflammatory diseases.

Regulatory T cells in experimental colitis

Induction and maintenance of peripheral tolerance are important mechanisms to maintain the balance of the immune system. Growing evidence indicates that dysregulation of mucosal T cell responses may lead to loss of tolerance to commensal flora and to the development of inflammatory bowel diseases (IBD). Many studies suggest that active suppression of enteroantigen reactive cells mediated by regulatory T cells contributes to the maintenance of natural intestinal immune homeostasis. The use of the multiple animal models has not only improved our understanding of IBD, but also contributed to new suggestions of treatment strategies involving the use of regulatory T cells. The present review summarizes our current knowledge of regulatory T cells and their involvement in experimental IBD. The well-characterized SCID T cell transfer model and the naturally occurring regulatory CD4+CD25+ T cells are highlighted.

Monoassociation of SCID mice with Helicobacter muridarum, but not four other enterics, provokes IBD upon receipt of T cells

BACKGROUND & AIMS

Recently, a number of animal models for different aspects of inflammatory bowel disease (IBD) have been developed. The aim of this study was to use one of these to determine whether particular, ostensibly innocuous, intestinal bacteria could provoke or exacerbate IBD.

METHODS

Conventionally reared C.B17 SCID mice were compared with germ-free and gnotobiotic mice, monoassociated with 1 of 5 intestinal bacteria, after transfer of CD45RB(high) CD4(+) T cells from conventionally reared congenic BALB/c mice. Recipient mice were monitored over 7-12 weeks for clinical signs of IBD, and tissues were analyzed by histology/flow cytometry for abnormal inflammation and CD4(+) T cell outgrowth.

RESULTS

Neither germ-free mice nor mice monoassociated with segmented filamentous bacteria, Ochrobactrum anthropi, a nonpathogenic mutant of Listeria monocytogenes, or Morganella morganii developed any signs of IBD. In contrast, mice monoassociated with Helicobacter muridarum displayed an accelerated development of IBD in 5-6 weeks compared with 8-12 weeks observed in conventionally reared mice. The outgrowth of CD4(+) T cells in spleen and large intestine of H. muridarum monoassociated mice, as well as in conventionally reared mice was significantly higher than that in the other monoassociated mice.

CONCLUSIONS

Among the intestinal bacteria tested, H. muridarum can serve as a provocateur of IBD in this model.

Clustering of colonic lamina propria CD4(+) T cells to subepithelial dendritic cell aggregates precedes the development of colitis in a murine adoptive transfer model

Initial lesions in inflammatory bowel disease induced during the repopulation of immunodeficient RAG1(-/-) mice with immunocompetent CD4(+) T cells have not been previously described. In this transfer colitis model, we followed CD4(+) T cell repopulation in the host by injecting autofluorescent CD4(+) T cells from congenic, enhanced green fluorescent protein (eGFP)-transgenic mice. This allowed the direct, sensitive, and unambiguous histological detection of the repopulation of the intestinal tract, mesenteric lymph nodes, and spleen of the host with donor eGFP(+) CD4(+) T cells. We identified in RAG1(-/-) mice intestinal dendritic cell (DC) aggregates under the basal crypt epithelium at the mucosa/submucosa junction from which F4/80(+) macrophages were excluded. At Days 8 to 11 posttransfer (before colitis was manifest), CD4(+) T cells clustered and proliferated in CD11c(+) DC aggregates. T cell clustering was most pronounced in the cecum where histologically overt colitis became manifest 5 to 10 days later. Junctional DC aggregates were thus prevalent in the triggering phase of the disease. The data suggest that pathogenic T cell responses inducing inflammatory bowel disease are primed or restimulated in situ in junctional CD4(+) T cell/DC aggregates.

Enteric bacterial antigens activate CD4(+) T cells from scid mice with inflammatory bowel disease

Scid mice transplanted with CD4(+) T cells from congenic donor mice develop a chronic and lethal inflammatory bowel disease (IBD) 2-3 months post-transplantation. In the present study we have investigated the response of CD4(+) T cells from scid mice with colitis against fecal extracts. Our results show that in contrast to CD4(+) T cells from normal BALB/c mice, CD4(+) T cells from scid mice with colitis proliferate strongly in response to antigen-presenting cells (APC) pulsed with fecal extracts. The IBD-associated T cells did not respond to either extracts from food antigens or fecal extracts from germ-free mice, which indicates that they recognize bacterial antigens in the fecal extracts. CD4(+) T cells isolated from the colonic lamina propria of scid mice 3 weeks post transplantation also responded vigorously to fecal extracts, demonstrating that reactive CD4(+) T cells are present in the gut mucosa of transplanted scid mice prior to clinical manifestations of IBD. CD4(+) T cells activated by fecal extracts produced high amounts of IL-2 and IFN-gamma, intermediate amounts of IL-4 and low amounts of IL-10, consistent with a Th1 profile. The proliferative reactivity towards fecal extracts was restricted by MHC class II molecules and dependent on antigen processing, as the response could be blocked by anti-MHC class II antibodies or a short fixation of the APC. This study demonstrates that class II-restricted CD4(+) Th1 cells, which recognize enteric bacterial antigens, infiltrate the gut mucosa and spleen of transplanted scid mice prior to and during the course of colitis.

Autoimmune intestinal pathology induced by hsp60-specific CD8 T cells

Due to their ubiquitous distribution and high degree of structural similarity, heat shock proteins (hsp) are potential target antigens in autoimmune diseases. Here, we describe induction of intestinal inflammation following transfer of hsp60-reactive CD8 T cells into mice. Inflammatory reactions were MHC class I dependent and developed primarily in the small intestine. IFN gamma and TNF alpha, as well as gut-derived hsp60, were elevated at sites of T cell infiltration. Intestinal lesions were drastically reduced in mice lacking receptors for TNF alpha. Pathology also developed in germ-free mice, indicating recognition of host-derived hsp60 by CD8 T cells. This report demonstrates that CD8 T cells with defined antigen specificity cause intestinal inflammation, emphasizing a link between infection and autoimmune disease.

Proliferation and apoptosis of lamina propria CD4+ T cells from scid mice with inflammatory bowel disease

Scid mice transplanted with low numbers of syngeneic CD4+ T cells, develop a chronic and lethal inflammatory bowel disease (IBD) within 4-6 months. We have used in vivo 5-bromo2-deoxy-uridine (BrdU) labeling to assess the proliferation of lamina propria-derived CD4+ T cells in diseased scid mice. The hourly rate of renewal of colonic lamina propria CD4+ T cells in diseased mice was 7% compared with 1.5% in normal BALB/c control mice. Transplantation of scid mice with in vitro activated CD4+ T cells accelerated the disease onset and development in a cell dose-dependent fashion when compared with non-activated CD4+ T cells. In pulse-chase experiments it was shown that BrdU-labeled cells disappeared rapidly from the lamina propria of diseased mice. DNA analysis revealed that this was due to the presence of nearly four times as many apoptotic CD4+ T cells in diseased than in control mice. Further analyses showed that the apoptotic lamina propria CD4+ T cells were derived from cells having entered the cell cycle within the previous 8 h. These data clearly demonstrate that vigorous CD4+ T cell proliferation and death are involved throughout the course of IBD.

Accumulation of immunoglobulin-containing cells in the gut mucosa and presence of faecal immunoglobulin in severe combined immunodeficient (scid) mice with T cell-induced inflammatory bowel disease (IBD)

Scid mice transplanted either with a gut wall graft or with low numbers of purified CD4+ T cells from immunocompetent syngeneic donor mice show clinical signs of IBD 3-4 months post-transplantation. The disease is mediated by mucosa-infiltrating CD4+ TCR alphabeta+ T cells. The pathology of 52 individual colon segments obtained from 20 gut wall- or CD4+ T cell-transplanted diseased scid mice was evaluated by histology and the numbers of infiltrating immunoglobulin-containing cells were determined. In particular, cells positive for IgM, IgA and non-inflammatory immunoglobulin isotypes such as IgG1 and IgG2b were found to accumulate in colon segments displaying the most severe histopathology, including inflammatory cellular infiltration, epithelial hyperplasia and ulcerative lesions. Compared with colon segments of normal C.B-17 mice, the lesional scid colon shows increased levels of cells positive for the IgG classes. Faecal extracts of the CD4+ T cell-transplanted scid mice revealed the presence of all six murine immunoglobulin isotypes. Disease progression was accompanied by an increased level of excreted IgM and IgG3 and decreased levels of IgA. It is concluded that locally secreted immunoglobulins may play an immunomodulating role in the pathological changes observed in the present model of T cell-induced inflammatory bowel disease.

Increased intracellular Th1 cytokines in scid mice with inflammatory bowel disease

Severe combined immunodeficient (scid) mice engrafted with small pieces of full thickness gut wall from immunocompetent syngenic donors develop a chronic and lethal colitis. Lymphocytes from the lamina propria of engrafted mice were analyzed for phorbol ester/ionomycin-induced cytokine production by intracellular staining. A 4-5-fold increase in the fraction of IFN-gamma-producing CD4+ lamina propria T cells was found in moderately and severely diseased mice when compared to healthy congenic C.B-17 control mice. The number of IL-2-producing T cells was increased by approximately 2-fold when comparing mice suffering from severe disease to healthy control mice. The fraction of TNF-alpha positive CD4+ T cells was increased by a factor of two in both moderately and severely diseased mice. When analyzing Th2 cytokines, it was found that the levels of IL-4-producing CD4+ T cells was not altered in diseased animals, whereas the fraction IL-10-producing CD4+ T cells was reduced by a factor of 20. The combined data showed a 15-25-fold increase in the Th1/Th2 ratio of diseased mice when compared to healthy control mice. No intracellular cytokines could be detected in lymphocytes not treated with phorbol ester/ionomycin. The present data identify a prominent role for Th1-type T helper cells in the immunopathogenesis of gut wall graft-induced inflammatory bowel disease in scid mice.

T-cell transfer and cytokine/TCR gene deletion models in the study of inflammatory bowel disease

Until recently there existed no appropriate immunological animal models for human inflammatory bowel diseases (IBD). Today a number of models, mostly in the mouse and rat, have proved useful in the study of several aspects of IBD, including the histopathology and the disease-inductive and -protective cell types, subsets and cytokines, for example CD4+ T cells, IFN gamma, IL-12, IL-2, IL-10 and TGF beta. Furthermore, these recent IBD models make it possible to examine various chemo- and immunotherapeutic approaches. This review focuses on IBD development in adoptive T-cell transfer models and in gene-deleted mice.

Polyclonal expansion of adoptively transferred CD4+ alpha beta T cells in the colonic lamina propria of scid mice with colitis

The adoptive transfer of low numbers of peripheral, non-fractionated CD4+ alpha beta T cells into histocompatible, severely immunodeficient (scid) hosts induces a colitis. This disease developed in C.B-17 scid/scid hosts after the injection of 10(5) CD4+ T cells purified from different peripheral lymphoid organs of immunocompetent C.B.-17 +/+ or BALB/cdm2 donor mice. Irrespective of their tissue origin, transferred CD4+ T cells selectively repopulated the scid host with gut-seeking CD4+ T cells. A chronic inflammatory bowel disease (IBD) developed as polyclonal populations of mucosa-seeking memory/effector CD4+ T cells accumulated in the gut lamina propria and epithelial layer of the adoptive host. The manifestation of colitis in the scid host correlated with the in situ polyclonal activation and expansion of adoptively transferred CD4+ T cells in the colonic lamina propria. Attempts were unsuccessful to select in vivo an oligoclonal CD4+ T cell population with an enhanced IBD-inducing potential by repeatedly reinjecting 10(5) donor-type CD4+ T cells from the colonic lamina propria of transplanted scid mice with an early and severe IBD into new scid hosts. The data indicate that the preferential repopulation of gut-associated lymphoid tissues with immunocompetent CD4+ T cells, and their polyclonal activation and in situ expansion in the lamina propria of the histocompatible, immunodeficient host are critical events in the pathogenesis of an IBD in this model.

Co-expression of CD8 alpha in CD4+ T cell receptor alpha beta + T cells migrating into the murine small intestine epithelial layer

We investigated the surface phenotype of CD3+CD4+ T cell receptor (TCR) alpha beta + T cells repopulating the intestinal lymphoid tissues of C.B-17 scid/scid (severe-combined immunodeficient; scid) (H-2d, Ld+) mice. CD4+ CD8- T cells were cell sorter-purified from various secondary and tertiary lymphoid organs of congenic C.B-17 +/+ (H-2d, Ld+) or semi-syngeneic dm2 (H-2d, Ld-) immunocompetent donor mice. After transfer of 10(5) cells into young scid mice, a mucosa-homing, memory CD44hi CD45RBlo CD4+ T cell population was selectively engrafted. Large numbers of single-positive (SP) CD3+ CD2+ CD28+ CD4+ CD8- T cells that expressed the alpha 4 integrin chain CD49d were found in the spleen, the mesenteric lymph nodes, the peritoneal cavity and the gut lamina propria of transplanted scid mice. Unexpectedly, large populations of donor-type double-positive (DP) CD4+ CD8 alpha + CD8 beta - T cells with high expression of the CD3/TCR complex appeared in the epithelial layer of the small intestine of transplanted scid mice. In contrast to SP CD4+ T cells, the intraepithelial DP T cells showed low expression of the CD2 and the CD28 co-stimulator molecules, and of the alpha 4 integrin chain CD49d, but expressed high levels of the alpha IEL integrin chain CD103. The TCR-V beta repertoire of DP but not SP intraepithelial CD4+ T cells was biased towards usage of the V beta 6 and V beta 8 viable domains. Highly purified populations of SP and DP CD4+ T cell populations from the small intestine epithelial layer of transplanted scid mice had different abilities to repopulate secondary scid recipient mice: SP CD4+ T cells repopulated various lymphoid tissues of the immunodeficient host, while intraepithelial DP CD4+ T cells did not. Hence, a subset of CD3+ CD4+ TCR alpha beta + T cells apparently undergoes striking phenotypic changes when it enters the microenvironment of the small intestine epithelial layer.

A gut-homing, oligoclonal CD4+ T cell population in severe-combined immunodeficient mice expressing a rearranged, transgenic class I-restricted alpha beta T cell receptor

We studied the peripheral T cell compartment of H-2b severe combined immunodeficient (scid) mice that express a transgenic (tg) alpha beta T cell receptor (TcR) specific for the H-Y (male) epitope presented by the H-2 class I Db molecule. Large populations of CD3+ NK1.1-TCR beta T+ T cells were present in spleen, mesenteric lymph nodes, peritoneal cavity, lamina propria and epithelial layer of the small and large intestine of 6- to 10-month-old, male and female tg scid mice. Only low numbers of CD3+ T cells were recovered from inguinal, popliteal, or axillary lymph nodes. We studied CD4+ T cells in these tg scid mice. CD4+ T cells were found in the peritoneal cavity, in the mesenteric lymph nodes and in the intraepithelial layer and lamina propria of the gut. All CD4+ T cells were CD44+ (i.e. showed evidence of antigen-driven differentiation) and expressed the tg V beta 8.2 TcR beta-chain (TcR beta T+). Only few CD4+ T cells expressed the tg V alpha 3+ TcR alpha-chain (TcR alpha T). cDNA was prepared from CD4+ T cells from spleen or mesenteric lymph nodes of individual male and female tg scid mice; sequence analyses of polymerase chain reaction-amplified, endogenous TcR alpha-chain (TcR alpha E) transcripts indicated that > 90% of the TcR alpha E-chain transcripts were in-frame, that the TcR alpha E repertoire in CD4+ T cell populations was oligoclonal, and that the TcR alpha E repertoire was different in individual tg scid mice. Hence, an oligoclonal, leaky CD4+ T cell population is selected in tg scid mice that apparently responds to gut-derived antigens. No inflammatory bowel disease (IBD) was evident in the small or large intestine of 6- to 10-month old tg scid mice. After adoptive transfer of purified CD4+ T cells (10(5) cells per mouse) from tg scid mice into non-tg H-2b scid mice, CD4+ TcR alpha T-beta T+ cells were found in gut tissues of the immunodeficient host. Transplanted scid mice developed clinical and histological signs of IBD. An oligoclonal, gut-homing, memory/effector CD4+ CD44+ TcR beta T+ TcR alpha T-T cell subset from leaky tg scid mice thus has a pathogenic potential when released from the control of TcR beta T+ TcR alpha T+ T cells.

Gut-homing CD4+ T cell receptor alpha beta+ T cells in the pathogenesis of murine inflammatory bowel disease

We studied which T cell subsets from the gut-associated lymphoid tissue (GALT) can migrate out of the gut mucosa and repopulate GALT compartments of an immunodeficient (semi)syngeneic host. Many distinct lymphocyte subsets were found in GALT of immunocompetent H-2d (BALB/c, BALB/cdm2, C.B-17+/+) mice. No antigen receptor-expressing lymphoid cells were found in GALT of congenic C.B-17 scid/scid (scid) mice. The heterotopic transplantation of a full-thickness gut wall graft from the ileum or colon of immunocompetent (C.B-17+/+, BALB/cdm2) donor mice onto immunodeficient scid mice selectively reconstituted a CD3+ T cell receptor alpha beta+ CD4+ T cell subset. CD4+ cells of this subset expressed the surface phenotype of mucosa-seeking, memory T cells. In the immunodeficient scid host, this gut-derived CD4+ T cell subset was found in spleen, peritoneal cavity, mesenteric lymph nodes (LN), epithelial layer and lamina propria of the small and large intestine, but not in peripheral LN. Scid mice heterotopically transplanted with gut from a congenic, immunocompetent donor developed clinical and histological signs of inflammatory bowel disease (IBD). Hence, the selective repopulation of GALT compartments with CD4+ T cells from normal GALT plays an essential role in the pathogenesis of IBD in an immunodeficient host.

Adoptive transfer of low numbers of CD4+ T cells into SCID mice chronically treated with soluble IL-4 receptor does not prevent engraftment of IL-4-producing T cells

After intravenous injection of 10(5) purified, lymph node (LN)-derived dm2 (H-2d/Ld-) CD4+ T cells into young C.B-17 scid/scid (severe combined immunodeficiency, SCID) mice (H-2d/Ld+), the transplanted Ld-T cells show a selective pattern of engraftment: they repopulate the spleen, the lamina propria of the small intestine and the mesenteric LN (but not other peripheral LN) of the immunodeficient host. CD4+ cells repopulating different lymphoid organs of the SCID recipient mice produce interleukin-2 (IL-2) and interleukin-4 (IL-4) in response to polyclonal stimulation in vitro. Some evidence has recently been provided that cytokines (e.g. IL-4) present at the site of antigen stimulation in vivo decisively influence the pattern of cytokines expressed by T cells activated at these sites. We therefore asked if neutralization of IL-4 by chronic treatment of SCID mice with high doses of recombinant soluble IL-4 receptor (sIL-4R) changes the IL-4 or IL-2 expression pattern of CD4+ T cells adoptively transferred into young SCID recipients. Transplanted SCID mice were chronically treated with two different, recombinant murine sIL-4R proteins. The experimental series further included groups of transplanted SCID mice treated with a recombinant human sIL-4R protein (which does not bind murine IL-4), treated with the anti-murine IL-4 monoclonal antibody (MoAb) 11B11, or non-treated. Transplanted SCID mice treated with the recombinant murine sIL-4R protein preparations displayed detectable sIL-4R serum levels, which demonstrates that the substitution therapy could maintain neutralizing serum levels of anti-IL-4 activity in SCID mice. By contrast, no serum sIL-4R levels were detectable in the sensitive ELISA readout in transplanted SCID mice which were non-treated, treated with the MoAb 11B11, or treated with the recombinant humans sIL-4R protein. The efficiency and the pattern of CD4+ T-cell engraftment, and the lymphokine-producing phenotype of the engrafted dm2 CD4+ cells, was not affected by the continuous IL-4-neutralizing treatment of mice with either the MoAb 11B11 or the soluble IL-4R preparations. Hence, in contrast to the published evidence of the dramatic effect of IL-4 on the lymphokine-producing phenotype of CD4+ T cells stimulated in vitro or in vivo, the chronic suppression in vivo of IL-4 activity (by either different sIL4-R protein constructs, or by the anti-IL-4 MoAb 11B11) did not lead to preferential engraftment of Th1-type CD4+ T cells after adoptive transfer of CD4+ T-cell populations into an immunodeficient recipient.