Suppression of hepatic lesions in a murine graft-versus-host reaction by antibodies against adhesion molecules

Gas6 deficiency in recipient mice of allogeneic transplantation alleviates hepatic graft-versus-host disease

Growth arrest-specific gene 6 (Gas6) is expressed in antigen-presenting cells and endothelial cells (ECs) but not in T cells. When wild-type (WT) or Gas6(-/-) mice received allogeneic non-T cell-depleted bone marrow cells, hepatic graft-versus-host disease (GVHD) was alleviated in Gas6(-/-) recipients regardless of donor genotype, but not in WT recipients. T-cell infiltration was more prominent and diffuse in WT than in Gas6(-/-) recipients' liver. When mice received 0.5 x 10(6) allogeneic T cells with T cell-depleted allogeneic bone marrow, clinical signs indicated that GVHD was less severe in Gas6(-/-) than in WT recipients, as shown by a significant improvement of the survival and reduced liver GVHD. These data demonstrate that donor cells were not involved in the protection mechanism. In addition, lack of Gas6 in antigen-presenting cells did not affect WT or Gas6(-/-) T-cell proliferation. We therefore assessed the response of WT or Gas6(-/-) ECs to tumor necrosis factor-alpha. Lymphocyte transmigration was less extensive through Gas6(-/-) than WT ECs and was not accompanied by increases in adhesion molecule levels. Thus, the lack of Gas6 in ECs impaired donor T-cell transmigration into the liver, providing a rationale for considering Gas6 pathway as a potential nonimmunosuppressive target to minimize GVHD in patients receiving allogeneic hematopoietic stem cell transplantation.

Regulatory T cells and liver pathology in a murine graft versus host response model

AIM

We have previously reported in mice the hepatic inflammatory in graft versus host response (GVHR) model due to the disparity of major histocompatibility complex class-II. The regulatory T (Treg) cells have been reported to control excessive immune response and prevent immune-related diseases. This study aimed to investigate the pathogenesis profiles of chronic GVHR progression, focusing on the Treg cells.

METHODS

GVHR mice induced by parental spleen CD4(+) T cell injection were sacrificed after 0, 2, 4, and 8 weeks (G0, G2, G4, G8). Further, one GVHR group received anti-IL-10 antibody in advance and were maintained for 2 weeks. Pathologic profiles of hepatic infiltrating inflammatory cells were evaluated by haematoxylin and eosin and immunohistochemistry staining with surface markers including Treg cell markers.

RESULTS

Remarkable hepatic inflammatory in G2 significantly and gradually improved over time up to G8. In immunohistochemical staining, the increased IL-10 receptor beta(+) Tr1 cells in G2 were maintained through to G8; although other inflammatory cells decreased from G2 to G8. By contrast, in the anti-IL-10 antibody received-GVHR mice, the Tr1 cells were not detectable with significant inflammatory aggravation, while FoxP3(+) Treg cells significantly enhanced.

CONCLUSIONS

These findings in the GVHR mice suggest that the expression and activity of Treg cells, especially the Tr1 cells, might be key factors for pathologic alteration in immune-related liver disease.

Short-term homing assay reveals a critical role for lymphocyte function-associated antigen-1 in the hepatic recruitment of lymphocytes in graft-versus-host disease

BACKGROUND/AIMS

The liver is a major target organ of graft versus host disease (GvHD) with massive infiltration of alloreactive lymphocytes resulting in hepatitis and hepatocyte injury. Although adhesive mechanisms have been implicated in the biology of GvHD hepatitis, the identity of homing receptors involved in the initial recruitment of cells from the blood is not known.

METHODS

We have developed a short-term homing assay in a model of murine GvHD. Splenocytes from donors at an active stage of GvHD were injected intravenously into adoptive recipients also undergoing GvHD. The recruitment of cells to the liver was assessed 6h after cell transfer.

RESULTS

Activated donor CD8 and CD4 lymphocytes expressed lymphocyte function antigen-1 (LFA-1), alpha4-integrins, and P-selectin binding ligands, and localized more efficiently than naïve T cells. Immunoneutralization of LFA-1 reduced the recruitment of CD8 and CD4 lymphocytes to the liver by more than 60%. Anti-LFA-1 antibody also markedly reduced infiltration of lymphocytes in periportal areas and protected against hepatocellular damage.

CONCLUSIONS

We demonstrate a critical role of LFA-1 in the recruitment of activated lymphocytes to the liver and in immune-cell mediated hepatitis. LFA-1 may be an effective therapeutic target for protecting the liver following bone marrow transplantation.

A Revision of Billingham’s Tenets: The Central Role of Lymphocyte Migration in Acute Graft-versus-Host Disease

The migration of cells from vascular to extravascular compartments effects a sequential cascade of events, involving an interplay between adhesion molecules and chemokines. All T cell-mediated immune responses, of which acute graft-versus-host disease (GVHD) is an example, require that effector cells reach their target tissues. Lymphocytes do not enter specific tissues because they "see" a given antigen; they enter because they possess the requisite combination of homing receptors and chemokine receptors to engage the endothelium at the target tissue(s). Billingham's tenets on the immunobiology of GVHD must be expanded to accommodate this obligatory homing component. Because GVHD is relatively organ specific--principally affecting the skin, gut, and liver-our increasing knowledge of the pertinent adhesion molecules and chemokines directing effector cell trafficking to these sites offers novel therapeutic approaches for prevention or treatment of GVHD. The potential efficiency of this form of therapy could eliminate the use of graft manipulations (eg, T-cell depletion) and broad immunosuppressives, thereby lessening infectious complications and preserving the potent graft-versus-malignancy effect of allogeneic hematopoietic stem cell transplantation.

Therapeutic anti-integrin (alpha4 and alphaL) monoclonal antibodies: two-edged swords?

Anti-alpha4 and anti-alphaL integrin chain monoclonal antibodies have shown a clear-cut beneficial effect in different animal models of autoimmune and inflammatory disorders as well as in human diseases, including multiple sclerosis, inflammatory bowel disease, and psoriasis. It has been widely assumed that this therapeutic effect is mainly consequence of the blockade of leucocyte adhesion to endothelium, inhibiting thus their extravasation and the inflammatory phenomenon. However, it is evident that both alpha4beta1 (very late antigen-4) and alphaLbeta2 (leucocyte function-associated antigen-1) integrins have additional important roles in other immune phenomena, including the formation of the immune synapse and the differentiation of T helper 1 lymphocytes. Therefore, it is very feasible that the long-term administration of blocking agents directed against these integrins to patients with inflammatory/autoimmune conditions may have undesirable or unexpected effects.

T-cell P/E-selectin ligand α(1,3)fucosylation is not required for graft-vs-host disease induction

OBJECTIVE

Recognition of E- and P-selectins on vascular endothelium by their leukocyte glycoprotein counterreceptor P-selectin glycoprotein ligand-1 (PSGL-1) initiates and sustains leukocyte rolling, culminating in extravasation of lymphocytes from blood into organs. PSGL-1 is rendered functional by terminal glycosylation steps, which occur mainly in activated Th1 but not Th2 cells. alpha(1,3)Fucosyltransferases IV and VII control this glycosylation pathway. Mice lacking these transferases (Fuc-TIV(-/-)/Fuc-TVII(-/-)) lack functional E- and P-selectin ligands. We hypothesized that Fuc-TIV(-/-)/Fuc-TVII(-/-) donor T cells might have reduced capacity to roll on vessels of inflamed target tissues and mediate graft-vs-host disease (GVHD).

MATERIALS AND METHODS

We compared the ability of Fuc-TIV(-/-)/Fuc-TVII(-/-) and wild-type (WT) C57BL/6 (B6) spleen cells (SPCs) to produce GVHD in lethally irradiated major histocompatibility complex (MHC) haplotype-mismatched B6D2F1 recipients. Clinical GVHD, GVHD pathology in target organs, memory phenotype conversion, proliferation of donor T cells, and tissue and serum cytokine expression were examined.

RESULTS

Surprisingly, clinical GVHD was not reduced in lethally irradiated mice receiving full haplotype MHC mismatched or matched Fuc-TIV(-/-)/Fuc-TVII(-/-) SPCs compared to those receiving WT SPCs. GVHD pathology in target organs, memory phenotype conversion, and proliferation of donor T cells were similar in both groups. However, reduced interferon-gamma was detected in liver and lung, and serum levels of tumor necrosis factor-alpha were higher in mice receiving Fuc-TIV(-/-)/Fuc-TVII(-/-) SPCs compared with WT SPCs.

CONCLUSIONS

These results suggest that donor T cells, including Th1, are capable of trafficking to GVHD target tissues independently of P- and E- selectin ligand in conditioned hosts.

Leukocyte migration and graft-versus-host disease

Graft-versus-host disease (GVHD) remains a significant complication of allogeneic bone marrow transplantation (allo-BMT). Acute GVHD is mediated by immunocompetent donor T cells, which migrate to lymphoid tissues soon after infusion, recognize host alloantigens, and become activated upon interaction with host antigen-presenting cells (APCs). Recent work from our group and others suggests that activated effector T cells exit lymphoid tissues and traffic to mucosal sites and parenchymal target organs such as the gastrointestinal (GI) tract, liver, lung, and skin where they cause tissue damage. The molecular interactions necessary for effector cell migration during GVHD have become the focus of a growing body of research, as these interactions represent potential therapeutic targets. In this review we discuss chemokine and chemokine receptor interactions and adhesion molecules that have been shown to play roles in effector cell migration in experimental GVHD models, and we discuss a potential model for the role of chemokines during the activation phase of GVHD.

The molecular basis of salivary gland involvement in graft--vs.--host disease

During the past two decades, the involvement of salivary glands in graft vs. host disease (GVHD) had been intensively researched and published. GVHD occurs in 40-70% of patients treated with bone marrow and peripheral blood stem cell transplantation (PBSCT), and improved survival rates have led to a continuously increasing number of GVHD patients suffering from induced salivary insult. Limited studies suggest that a large percentage of GVHD patients is affected and that the induced salivary dysfunction occurs rapidly following the transplantation. It affects both major and minor salivary glands and reflects the severity of the disease. Moreover, profound sialochemical alterations may be diagnostic of GVHD. An additional reason for this vast research is that GVHD, as an autoimmune-like disease, seemed to be an appropriate model for studying a much more prevalent and well-known and well-studied autoimmune disease involving salivary glands: Sjögren's syndrome. The purpose of the current review-which is, to the best of our knowledge, the first of its kind-is to describe the GVHD-related sialometric and sialochemical data published in the past two decades for both major and minor salivary glands and to discuss the pathogenesis and molecular basis of the disease.

The Mortimer M. Bortin lecture

The graft-versus-leukemia effect of allogeneic blood or marrow transplantation is a dramatic example of the power of the immune system to eradicate malignant disease. In this personal essay, adapted from the inaugural Mortimer M. Bortin Lecture presented at the 2004 Tandem BMT Meetings, the author recounts early efforts by Bortin and others to manipulate the graft-versus-leukemia effect and separate it from the potentially fatal complications of graft-versus-host disease.

Significance of selectively targeted apoptotic rete cells in graft-versus-host disease

Considerable data exist regarding the mechanisms of allostimulation and homing (the effector phases) in graft-versus-host disease (GVHD). Current dogma suggests that target specificity involves preferential injury to epithelial surfaces of the skin and squamous mucosae, liver, and gut. Little attention has been devoted, however, to mechanisms of cellular targeting or to whether heterogeneity exists in target tissues with regard to a threshold for cellular injury. A recent breakthrough in understanding the target stage of GVHD indicates that the predominant pathway of injury to squamous epithelial cells involves apoptosis. Moreover, apoptotic injury may be associated or unassociated with local T-cell infiltration and involves phenotypically and antigenically distinctive epithelial cells within the basal layer of the skin and squamous mucosa. These cells are confined to rete ridges in the skin and retelike prominences in the dorsal tongue and are designated as selectively targeted apoptotic rete (STAR) cells. The discovery of STAR cells in GVHD paves the way for speculation and experimentation to determine why these subpopulations are selectively vulnerable and how soluble and cellular effectors of apoptosis contribute to their ultimate demise. Novel approaches to GVHD treatment derived from understanding mechanisms of selective epithelial injury are likely to use strategies to render target cells less susceptible to the apoptosis that is ultimately responsible for organ dysfunction and failure.

Cerebral endothelial expression of adhesion molecules in mice with chronic graft-versus-host disease

BACKGROUND AND PURPOSE

Graft-versus-host disease (GvHD) is a major complication after allogeneic bone marrow transplantation (BMT). The theory that the central nervous system (in addition to the peripheral nervous system) participates in GvHD has been supported by detection of cerebral lymphomononuclear infiltrates in experimental GvHD and the observation of cerebral angiitis-like disease in patients with chronic GvHD.

METHODS

In a murine BMT model, we investigated the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on cerebral endothelium after allogeneic and syngeneic transplantation. Through the use of ICAM-1-knockout mice, the effect of ICAM-1 deficiency on cellular infiltration was evaluated. As an indicator of enhanced apoptotic cell death, we examined the cerebral expression of Fas antigen (Fas), the occurrence of the poly-ADP ribose polymerase p85 fragment, and the distribution of TUNEL positive-stained cells.

RESULTS

In close correlation with earlier findings of cerebral infiltration in the same animals, we found cerebral endothelial upregulation of ICAM-1 and especially of VCAM-1 in allogeneic recipients compared with syngeneic animals without GvHD and unmanipulated controls. In ICAM-1-knockout mice, leukocytic infiltration did not differ from that in wild-type animals. Neither cerebral histopathologic changes nor an apoptotic effect of cellular infiltrates on brain parenchyma could be detected.

CONCLUSIONS

In this model of experimental GvHD, VCAM-1 may play a critical role in leukocyte recruitment into the central nervous system of animals with chronic GvHD.

Early changes in gene expression profiles of hepatic GVHD uncovered by oligonucleotide microarrays

The liver, skin, and gastrointestinal tract are major target organs of acute graft-versus-host disease (GVHD), the major complication of allogeneic bone marrow transplantation (BMT). In order to gain a better understanding of acute GVHD in the liver, we compared the gene expression profiles of livers after experimental allogeneic and syngeneic BMT using oligonucleotide microarray. At 35 days after allogeneic BMT when hepatic GVHD was histologically evident, genes related to cellular effectors and acute-phase proteins were up-regulated, whereas genes largely related to metabolism and endocrine function were down-regulated. At day 7 after BMT before the development of histologic changes in the liver, interferon gamma (IFN-gamma)-inducible genes, major histocompatibility (MHC) class II molecules, and genes related to leukocyte trafficking had been up-regulated. Immunohistochemistry demonstrated that expression of IFN-gamma protein itself was increased in the spleen but not in hepatic tissue. These results suggest that the increased expression of genes associated with the attraction and activation of donor T cells induced by IFN-gamma early after BMT is important in the initiation of hepatic GVHD in this model and provide new potential molecular targets for early detection and intervention of acute GVHD.

Novel expression of vascular cell adhesion molecule-1 (CD106) by squamous epithelium in experimental acute graft-versus-host disease

Vascular cell adhesion molecule-1 (VCAM-1; CD106), the receptor for VLA-4, is an important mediator of adhesive and co-stimulatory interactions that govern cutaneous immune responses. Initial studies designed to elucidate temporal aspects of endothelial adhesion molecule induction in murine acute graft-versus-host disease (aGVHD) revealed unexpected and novel VCAM-1 expression by cutaneous and mucosal epithelial cells. Immunohistochemical techniques confirmed VCAM-1 staining as early as 7 days after transplantation in a distinctive subpopulation of squamous epithelial cells that normally occupy focal domains within the epidermal basal cell layer, the follicular infundibulum, and the dorsal lingual epithelium. Specifically, VCAM-1 expression was intimately associated with rete ridge-like prominences in footpad epidermis and in dorsal lingual epithelium. VCAM-1, as evaluated by serial section-labeling techniques, was preferentially expressed at sites of early epithelial infiltration by CD4(+) T cells. Western blot analysis confirmed expression of the 110-kd isoform of VCAM-1 in epithelium isolated from aGVHD animals, and immunoelectron microscopy demonstrated VCAM-1 reactivity restricted exclusively to epithelial cell plasma membranes. It is concluded that VCAM-1 is selectively expressed by discrete squamous epithelial subpopulations in murine aGVHD. As such, VCAM-1 may play a previously unrecognized role in mediating interactions between donor effector T lymphocytes and host epithelial cell targets.

Novel murine autoimmune-mediated liver disease model induced by graft-versus-host reaction and concanavalin A

BACKGROUND AND AIMS

We have previously reported that cluster of differentiation (CD)4+ T cells induced autoimmune liver diseases in mice with graft-versus-host reaction (GVHR) because of major histocompatibility complex (MHC) class II disparity. To analyze the progression of the autoimmune-related mechanism in the liver, concanavalin A (Con A) was injected in mice undergoing GVHR. The aim of this study is to clarify whether Con A deteriorates murine hepatic lesions induced by GVHR, and to elucidate the participation of the cytokines of liver-infiltrating CD4+ T cells.

METHODS

Mice (F1; B6.C-H-2(bm12) x B6) were intravenously injected with B6 T spleen cells. Concanavalin A (15 mg/kg) was administrated 5 days after cell transfer. We examined serum transaminase, antimitochondrial antibodies (AMA), antinuclear antibodies (ANA) and histological changes. Liver-infiltrating CD4+ T cells were sorted and their cytokine mRNA expression was examined by the use of reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Graft-versus-host reaction + Con A mice revealed an elevated serum transaminase, elevated AMA and ANA titers, increased periportal cellular infiltration, piecemeal necrosis and bridging necrosis in the liver. In this group, interferon (IFN)-gamma mRNA expression was more elevated than it was in the GVHR mice. However, there was no difference in the expression of interleukin (IL)-10 mRNA between the two groups.

CONCLUSION

The results suggest that Con A deteriorates the GVHR-induced hepatic lesions, and IFN-gamma and IL-10 of CD4+ T cells might be implicated in the progression of autoimmune-related hepatic lesions. This model might offer an aspect for the investigation of progressive mechanisms in T-cell- mediated hepatobiliary injury.