Mast Cell-derived TNF Research Articles

Mast cell-derived mediators promote murine neutrophil effector functions

Mast cells are able to trigger life-saving immune responses in murine models for acute inflammation. In such settings, several lines of evidence indicate that the rapid and protective recruitment of neutrophils initiated by the release of mast cell-derived pro-inflammatory mediators is a key element of innate immunity. Herein, we investigate the impact of mast cells on critical parameters of neutrophil effector function. In the presence of activated murine bone marrow-derived mast cells, neutrophils freshly isolated from bone marrow rapidly lose expression of CD62L and up-regulate CD11b, the latter being partly driven by mast cell-derived TNF and GM-CSF. Mast cells also strongly enhance neutrophil phagocytosis and generation of reactive oxygen species. All these phenomena partly depend on mast cell-derived TNF and to a greater extend on GM-CSF. Furthermore, spontaneous apoptosis of neutrophils is greatly diminished due to the ability of mast cells to deliver antiapoptotic GM-CSF. Finally, we show in a murine model for acute lung inflammation that neutrophil phagocytosis is impaired in mast cell-deficient Kit (W-sh) /Kit (W-sh) mice but can be restored upon mast cell engraftment. Thus, a previously underrated feature of mast cells is their ability to boost neutrophil effector functions in immune responses.

The Chymase Mouse Mast Cell Protease 4 Degrades TNF, Limits Inflammation, and Promotes Survival in a Model of Sepsis

Mouse mast cell protease 4 (mMCP-4), the mouse counterpart of human mast cell chymase, is thought to have proinflammatory effects in innate or adaptive immune responses associated with mast cell activation. However, human chymase can degrade the proinflammatory cytokine TNF, a mediator that can be produced by mast cells and many other cell types. We found that mMCP-4 can reduce levels of mouse mast cell-derived TNF in vitro through degradation of transmembrane and soluble TNF. We assessed the effects of interactions between mMCP-4 and TNF in vivo by analyzing the features of a classic model of polymicrobial sepsis, cecal ligation and puncture (CLP), in C57BL/6J-mMCP-4-deficient mice versus C57BL/6J wild-type mice, and in C57BL/6J-Kit(W-sh/W-sh) mice containing adoptively transferred mast cells that were either wild type or lacked mMCP-4, TNF, or both mediators. The mMCP-4-deficient mice exhibited increased levels of intraperitoneal TNF, higher numbers of peritoneal neutrophils, and increased acute kidney injury after CLP, and also had significantly higher mortality after this procedure. Our findings support the conclusion that mMCP-4 can enhance survival after CLP at least in part by limiting detrimental effects of TNF, and suggest that mast cell chymase may represent an important negative regulator of TNF in vivo.

The chymase, mouse mast cell protease 4, degrades TNF, limits inflammation, and promotes survival in a mouse model of sepsis (151.3)

Abstract Mouse mast cell protease (mMCP)-4, the mouse counterpart of human mast cell chymase, is thought to have pro-inflammatory effects in innate or adaptive immune responses associated with mast cell activation. However, human chymase can degrade the pro-inflammatory cytokine, TNF, a mediator that can be produced by mast cells and many other cell types. We found that mMCP-4 can reduce levels of mouse mast cell-derived TNF in vitro through degradation of transmembrane and soluble TNF. We then searched for possible effects of interactions between mMCP-4 and TNF in vivo by analyzing the features of a classic model of polymicrobial sepsis, cecal ligation and puncture (CLP), in C57BL/6-mMCP-4-deficient mice versus C57BL/6 wild type mice, and in C57BL/6-KitW-sh/W-sh mice containing adoptively-transferred mast cells that were either wild type or lacked mMCP-4, TNF, or both mediators. We found that mMCP-4 reduced levels of intraperitoneal TNF and numbers of peritoneal neutrophils after CLP, and also significantly enhanced survival in mice subjected to this procedure. Our findings support the conclusion that mMCP-4 can enhance survival after CLP at least in part by limiting detrimental effects of TNF, and suggest that mast cell chymase may represent a physiologically important negative regulator of TNF.

Mast Cell-Derived TNF Can Exacerbate Mortality during Severe Bacterial Infections in C57BL/6- KitW-sh/W-sh Mice

We used mast cell-engrafted genetically mast cell-deficient C57BL/6-Kit(W-sh/W-sh) mice to investigate the roles of mast cells and mast cell-derived tumor necrosis factor in two models of severe bacterial infection. In these mice, we confirmed findings derived from studies of mast cell-deficient WBB6F(1)-Kit(W/W-v) mice indicating that mast cells can promote survival in cecal ligation and puncture (CLP) of moderate severity. However, we found that the beneficial role of mast cells in this setting can occur independently of mast cell-derived tumor necrosis factor. By contrast, using mast cell-engrafted C57BL/6-Kit(W-sh/W-sh) mice, we found that mast cell-derived tumor necrosis factor can increase mortality during severe CLP and can also enhance bacterial growth and hasten death after intraperitoneal inoculation of Salmonella typhimurium. In WBB6F(1)-Kit(W-sh/W-sh) mice, mast cells enhanced survival during moderately severe CLP but did not significantly change the survival observed in severe CLP. Our findings in three types of genetically mast cell-deficient mice thus support the hypothesis that, depending on the circumstances (including mouse strain background, the nature of the mutation resulting in a mast cell deficiency, and type and severity of infection), mast cells can have either no detectable effect or opposite effects on survival during bacterial infections, eg, promoting survival during moderately severe CLP associated with low mortality but, in C57BL/6-Kit(W-sh/W-sh) mice, increasing mortality during severe CLP or infection with S. typhimurium.

Direct crosstalk between mast cell–TNF and TNFR1-expressing endothelia mediates local tissue inflammation

AbstractSignaling through tumor necrosis factor receptor 1 (TNFR1) controls bacterial infections and the induction of inflammatory Th1 cell–mediated autoimmune diseases. By dissecting Th1 cell–mediated delayed-type hypersensitivity responses (DTHRs) into single steps, we localized a central defect to the missing TNFR1 expression by endothelial cells (ECs). Adoptive transfer and mast cell knockin experiments into KitW/KitW-v, TNF−/−, and TNFR1−/− mice showed that the signaling defect exclusively affects mast cell–EC interactions but not T cells or antigen-presenting cells. As a consequence, TNFR1−/− mice had strongly reduced mRNA and protein expression of P-selectin, E-selectin, ICAM-1, and VCAM-1 during DTHR elicitation. In consequence, intravital fluorescence microscopy revealed up to 80% reduction of leukocyte rolling and firm adhesion in TNFR1−/− mice. As substitution of TNF−/− mice with TNF-producing mast cells fully restored DTHR in these mice, signaling of mast cell-derived TNF through TNFR1-expressing ECs is essential for the recruitment of leukocytes into sites of inflammation.

Mast cell–derived TNF contributes to airway hyperreactivity, inflammation, and T H2 cytokine production in an asthma model in mice

Mast cells, IgE, and TNF, which have been implicated in human atopic asthma, contribute significantly to the allergic airway inflammation induced by ovalbumin (OVA) challenge in mice sensitized with OVA without alum. However, it is not clear to what extent mast cells represent a significant source of TNF in this mouse model. We investigated the importance of mast cell-derived TNF in a mast cell-dependent model of OVA-induced airway hyperreactivity (AHR) and allergic airway inflammation. Features of this model of airway inflammation were analyzed in C57BL/6J-wild-type mice, mast cell-deficient C57BL/6J-Kit(W-sh)(/W-sh) mice, and C57BL/6J Kit(W-sh/W-sh) mice that had been systemically engrafted with bone marrow-derived cultured mast cells from C57BL/6J-wild-type or C57BL/6J-TNF(-/-) mice. Ovalbumin-induced AHR and airway inflammation were significantly reduced in mast cell-deficient Kit(W-sh/W-sh) mice versus wild-type mice. By contrast, Kit(W-sh/W-sh) mice that had been engrafted with wild-type but not with TNF(-/-) bone marrow-derived cultured mast cells exhibited responses very similar to those observed in wild-type mice. Mast cells and mast cell-derived TNF were not required for induction of OVA-specific memory T cells in the sensitization phase, but significantly enhanced lymphocyte recruitment and T(H)2 cytokine production in the challenge phase. Mast cell-derived TNF contributes significantly to the pathogenesis of mast cell-dependent and IgE-dependent, OVA-induced allergic inflammation and AHR in mice, perhaps in part by enhancing lymphocyte recruitment and T(H)2 cytokine production. Our findings in mice support the hypothesis that mast cell-derived TNF can promote allergic inflammation and AHR in asthma.

Protective Roles of Mast Cells and Mast Cell-Derived TNF in Murine Malaria

TNF plays important roles in the protection and onset of malaria. Although mast cells are known as a source of TNF, little is known about the relationship between mast cells and pathogenesis of malaria. In this study, mast cell-deficient WBB6F1-W/W(v) (W/W(v)) and the control littermate WBB6F1+/+ (+/+) mice were infected with 1 x 10(5) of Plasmodium berghei ANKA. +/+ mice had lower parasitemia with higher TNF levels, as compared with W/W(v) mice. Diminished resistance in W/W(v) mice was considered to be due to mast cells and TNF. This fact was confirmed by experiments in W/W(v) mice reconstituted with bone marrow-derived mast cells (BMMCs) of +/+ mice or of TNF-/- mice. W/W(v) mice with BMMCs of +/+ mice exhibit lower parasitemia and mortality accompanying significantly higher TNF levels than those of W/W(v) mice. Parasitemia in W/W(v) mice with BMMCs of TNF-/- mice was higher than that in +/+ mice. Activation of mast cells by anti-IgE or compound 48/80 resulted in release of TNF and decrease of parasitemia. In addition, splenic hypertrophy and increased number of mast cells in the spleen were observed after infection in +/+ mice and W/W(v) mice reconstituted with BMMCs of +/+ mice as compared with W/W(v) mice. These findings propose a novel mechanism that mast cells and mast cell-derived TNF play protective roles in malaria.

Mast Cell-Associated TNF Promotes Dendritic Cell Migration

Mast cells represent a potential source of TNF, a mediator which can enhance dendritic cell (DC) migration. Although the importance of mast cell-associated TNF in regulating DC migration in vivo is not clear, mast cells and mast cell-derived TNF can contribute to the expression of certain models of contact hypersensitivity (CHS). We found that CHS to FITC was significantly impaired in mast cell-deficient Kit(W-sh/W-sh) or TNF(-/)(-) mice. The reduced expression of CHS in Kit(W-sh/W-sh) mice was fully repaired by local transfer of wild-type bone marrow-derived cultured mast cells (BMCMCs), but was only partially repaired by transfer of TNF(-/)(-) BMCMCs. Thus, mast cells, and mast cell-derived TNF, were required for optimal expression of CHS to FITC. We found that the migration of FITC-bearing skin DCs into draining lymph nodes (LNs) 24 h after epicutaneous administration of FITC in naive mice was significantly reduced in mast cell-deficient or TNF(-/)(-) mice, but levels of DC migration in these mutant mice increased to greater than wild-type levels by 48 h after FITC sensitization. Mast cell-deficient or TNF(-/)(-) mice also exhibited significantly reduced migration of airway DCs to local LNs at 24 h after intranasal challenge with FITC-OVA. Migration of FITC-bearing DCs to LNs draining the skin or airways 24 h after sensitization was repaired in Kit(W-sh/W-sh) mice which had been engrafted with wild-type but not TNF(-/)(-) BMCMCs. Our findings indicate that mast cell-associated TNF can contribute significantly to the initial stages of FITC-induced migration of cutaneous or airway DCs.

Mast cells enhance T cell activation: Importance of mast cell-derived TNF

Mast cells are not only important effector cells in immediate hypersensitivity reactions and immune responses to pathogens but also can contribute to T cell-mediated disorders. However, the mechanisms by which mast cells might influence T cells in such settings are not fully understood. We find that mast cells can enhance proliferation and cytokine production in multiple T cell subsets. Mast cell-dependent enhancement of T cell activation can be promoted by FcepsilonRI-dependent mast cell activation, TNF production by both mast cells and T cells, and mast cell-T cell contact. However, at high concentrations of cells, mast cells can promote T cell activation independent of IgE or TNF. Finally, mast cells also can promote T cell activation by means of soluble factors. These findings identify multiple mechanisms by which mast cells can influence T cell proliferation and cytokine production.

E‐selectin expression in salivary endothelial cells and sera from patients with systemic sclerosis

To assess endothelial cell activation in patients with systemic sclerosis (SSc). Concomitant study of salivary gland biopsy tissues and sera for expression of E-selectin and its potent activator tumor necrosis factor alpha (TNF alpha), using immunostaining and enzyme-linked immunosorbent essay. E-selectin was overexpressed in SSc patients, but not in controls. TNF alpha was detected in mast cells. Mast cell-derived TNF alpha may contribute to endothelial cell activation in SSc.

Mast Cell Degranulation Upregulates ∝6 Integrins on Epidermal Langerhans Cells

The expression of the alpha 6 beta 4 and alpha 6 beta 1 integrins on epidermal Langerhans cells (LC) before and after mast cell degranulation was studied in cultured human neonatal foreskin by immunohistochemistry. Twenty-four hours after addition of mast cell secretagogues, morphine sulfate, or substance P, solitary mid-epidermal cells showed staining for the integrin subunits alpha 6, beta 4, and beta 1. This expression was not observed in cultured control explants, and immunostained cells were confirmed to be non-epithelial, dendritic cells by immuno-electron microscopy. The identity of these cells as LC was further established by coincident staining for alpha 6 and CD1a using double immunofluorescence labeling. Addition of tumor necrosis factor-alpha (TNF alpha), the predominant cytokine in mast cell granules, also induced LC to express alpha 6 integrins. Furthermore, preincubation of skin organ cultures with anti-TNF alpha antibodies or the mast cell inhibitor cromolyn sodium abrogated the ability to induce alpha 6 integrins on LC consequent to experimental mast cell degranulation by substance P. These data implicate a role for mast cell-derived TNF alpha in the regulation of the integrins alpha 6 beta 4 and alpha 6 beta 1 on LC. These findings may have important implications relevant to mechanisms for spatial localization of LC within the cutaneous compartments during immune responses.