Fas ligand (FasL), an apoptosis-inducing member of the TNF cytokine family, and its receptor Fas are critical for the shutdown of chronic immune responses and prevention of autoimmunity. Accordingly, ...mutations in their genes cause severe lymphadenopathy and autoimmune disease in mice and humans. FasL function is regulated by deposition in the plasma membrane and metalloprotease-mediated shedding. Here we generated gene-targeted mice that selectively lack either secreted FasL (sFasL) or membrane-bound FasL (mFasL) to resolve which of these forms is required for cell killing and to explore their hypothesized non-apoptotic activities. Mice lacking sFasL (FasL(Deltas/Deltas)) appeared normal and their T cells readily killed target cells, whereas T cells lacking mFasL (FasL(Deltam/Deltam)) could not kill cells through Fas activation. FasL(Deltam/Deltam) mice developed lymphadenopathy and hyper-gammaglobulinaemia, similar to FasL(gld/gld) mice, which express a mutant form of FasL that cannot bind Fas, but surprisingly, FasL(Deltam/Deltam) mice (on a C57BL/6 background) succumbed to systemic lupus erythematosus (SLE)-like autoimmune kidney destruction and histiocytic sarcoma, diseases that occur only rarely and much later in FasL(gld/gld) mice. These results demonstrate that mFasL is essential for cytotoxic activity and constitutes the guardian against lymphadenopathy, autoimmunity and cancer, whereas excess sFasL appears to promote autoimmunity and tumorigenesis through non-apoptotic activities.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Oral and intestinal mucositis are debilitating inflammatory diseases observed in cancer patients undergoing chemo-radiotherapy. These are devastating clinical conditions which often lead to treatment ...disruption affecting underlying malignancy management. Although alimentary tract mucositis involves the entire gastrointestinal tract, oral and intestinal mucositis are often studied independently utilizing distinct organ-specific pre-clinical models. This approach has however hindered the development of potentially effective whole-patient treatment strategies. We now characterize a murine model of alimentary tract mucositis using 5-Fluorouracil (5-FU). Mice were given 5-FU intravenously (50 mg/kg) or saline every 48 h for 2 weeks. Post initial injection, mice were monitored clinically for weight loss and diarrhea. The incidence and extent of oral mucositis was assessed macroscopically. Microscopical and histomorphometric analyses of the tongue and intestinal tissues were conducted at 3 interim time points during the experimental period. Repeated 5-FU treatment caused severe oral and intestinal atrophy, including morphological damage, accompanied by body weight loss and mild to moderate diarrhea in up to 77.8% of mice. Oral mucositis was clinically evident throughout the observation period in 88.98% of mice. Toluidine blue staining of the tongue revealed that the ulcer size peaked at day-14. In summary, we have developed a model reproducing the clinical and histologic features of both oral and intestinal mucositis, which may represent a useful in vivo pre-clinical model for the study of chemotherapy-induced alimentary tract mucositis and the development of preventative therapies.
Oral and intestinal mucositis (OIM) are debilitating inflammatory diseases initiated by oxidative stress, resulting in epithelial cell death and are frequently observed in cancer patients undergoing ...chemo-radiotherapy. There are currently few preventative strategies for this debilitating condition. Therefore, the development of a safe and effective mucositis mitigating strategy is an unmet medical need. Hyaluronic acid (HA) preparations have been tentatively used in oral mucositis. However, the protective effects of HA in chemotherapy-induced mucositis and their underlying mechanisms remain to be fully elucidated. This study aimed to assess these mechanisms using multiple formulations of enriched HA (Mucosamin
), cross-linked (xl-), and non-crosslinked high molecular weight HA (H-MW-HA) in an oxidative stress-induced model of human oral mucosal injury in vitro and an in vivo murine model of 5-flurouracil (5-FU)-induced oral/intestinal mucositis. All tested HA formulations protected against oxidative stress-induced damage in vitro without inducing cytotoxicity, with H-MW-HA also significantly reducing ROS production. Daily supplementation with H-MW-HA in vivo drastically reduced the severity of 5-FU-induced OIM, prevented apoptotic damage and reduced COX-2 enzyme activity in both the oral and intestinal epithelium. In 5-FU-injected mice, HA supplementation also significantly reduced serum levels of IL-6 and the chemokine CXCL1/KC, while the serum antioxidant activity of superoxide dismutase was elevated. Our data suggest that H-MW-HA attenuates 5-FU-induced OIM, at least partly, by impeding apoptosis, inhibiting of oxidative stress and suppressing inflammatory cytokines. This study supports the development of H-MW-HA preparations for preventing OIM in patients receiving chemotherapy.
The use of immunosuppressive drugs in the management of autoimmunity penalizes a large part of the immune system for the misdemeanors of a small minority of T cells. An ideal form of therapy would be ...one in which it were possible to render the immune system tolerant of the inciting antigens with minimal effects on other responses. We here show that it is possible to re-establish self tolerance in an animal model of insulin-dependent diabetes mellitus without prior deletion of CD4+ T cells using a short course of therapy with a non-lytic monoclonal antibody to the CD4 adhesion receptor on T cells. This tolerance can be achieved even when diabetogenic cells are already in the pancreas. Primary responses to antigens given after therapy has ceased are normal and secondary responses to antigens seen prior to, but not during, the period of antibody therapy can remain unaffected. This suggests that intervention with selected CD4 antibodies may have significant advantages over and above that provided not only by conventional immunosuppression but also over that provided by a depleting antibody.
Fas ligand (FasL), an apoptosis-inducing member of the TNF cytokine family and its receptor, Fas, are critical for shutdown of chronic immune responses
1
-
3
and prevention of autoimmunity
4
,
5
. ...Accordingly, mutations in their genes cause severe lymphadenopathy and autoimmune disease in mice
6
,
7
and humans
8
,
9
. FasL function is regulated by deposition in the plasma membrane and metalloprotease-mediated shedding
10
,
11
. We generated gene-targeted mice that selectively lack either secreted FasL (ΔsFasL) or membrane-bound FasL (ΔmFasL) to resolve which of these forms is required for cell killing and to explore their hypothetical non-apoptotic activities. Mice lacking sFasL (
FasL
Δs/Δs
) appeared normal and their T cells readily killed target cells, whereas T cells lacking mFasL (
FasL
Δm/Δm
) could not kill cells through Fas activation.
FasL
Δm/Δm
mice developed lymphadenopathy and hyper-gammaglobulinaemia, similar to
FasL
gld/gld
mice, which express a mutant form of FasL that cannot bind Fas, but surprisingly, (on a C57BL/6 background)
FasL
Δm/Δm
mice succumbed to SLE-like autoimmune kidney destruction and histiocytic sarcoma, diseases that occur only rarely and considerably later in
FasL
gld/gld
mice. These results demonstrate that mFasL is essential for cytotoxic activity and constitutes the guardian against lymphadenopathy, autoimmunity and cancer whereas excess sFasL appears to promote autoimmunity and tumorigenesis through non-apoptotic activities.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Insulin-dependent diabetes mellitus (IDDM) is a disease with an autoimmune aetiology. The non-obese diabetic mouse is a good spontaneous animal model of the human disease, with IDDM developing in ...50-80% of female mice by the age of 6 months. The disease can be transferred by splenic T cells from diabetic donors and is prevented by T-cell depletion. The mechanism(s) by which the beta cell is specifically destroyed is not known, but T cells and macrophages have both been implicated, based on the presence of macrophages in the infiltrated islet and the ability of chronic silica treatment to prevent disease. The monoclonal antibody 5C6 is specific for the myelomonocytic adhesion-promoting type-3 complement receptor (CR3 or CD11b/CD18) and does not bind to T cells. Here we show that blockade of macrophage CR3 in vivo prevents intra-islet infiltration by both macrophages and T cells and inhibits development of IDDM. We conclude that both T cells and macrophages have an essential role in the onset of IDDM.
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