IL-13 but not IL-4 signaling via IL-4Rα protects mice from papilloma formation during DMBA/TPA two-step skin carcinogenesis

Interleukin 4 (IL-4) was shown to be tumor-promoting in full carcinogenesis studies using 3-methylcholanthrene (MCA). Because heretofore the role of IL-4 in DMBA/TPA (9,10-dimethyl-1,2-benz-anthracene/12-O-tetradecanoylphorbol-13-acetate) two-stage carcinogenesis was not studied, we performed such experiments using either IL-4(-/-) or IL-4R{alpha}(-/-) mice. We found that IL-4R{alpha}(-/-) but not IL-4(-/-) mice have enhanced papilloma formation, suggesting that IL-13 may be involved. Indeed, IL-13(-/-) mice developed more papillomas after exposure to DMBA/TPA than their heterozygous IL-13-competent littermate controls. However, when tested in a full carcinogenesis experiment, exposure of mice to 25 {My}g of MCA, both IL-13(-/-) and IL-13(+/-) mice led to the same incidence of tumors. While IL-4 enhances MCA carcinogenesis, it does not play a measurable role in our DMBA/TPA carcinogenesis experiments. Conversely, IL-13 does not affect MCA carcinogenesis but protects mice from DMBA/TPA carcinogenesis. One possible explanation is that IL-4 and IL-13, although they share a common IL-4R{alpha} chain, regulate signaling in target cells differently by employing distinct JAK/STAT-mediated signaling pathways downstream of IL-13 or IL-4 receptor complexes, resulting in different inflammatory transcriptional programs. Taken together, our results indicate that the course of DMBA/TPA- and MCA-induced carcinogenesis is affected differently by IL-4 versus IL-13-mediated inflammatory cascades

Cloning and characterization of TNKL, a member of tankyrase gene family.

By serological screening of a breast tumor cDNA library we have identified a novel human gene, tnkl, encoding an ankyrin-related protein with a high degree of similarity to tankyrase, the poly(ADP-ribose)polymerase associated with human telomeres (Smith et al, Science 282: 1484). The tnkl gene maps to chromosome 10, while the tnks gene encoding tankyrase is located on chromosome 8. The predicted 1166-aa protein product of the tnkl gene is 78% identical to human tankyrase and 62% to a putative D. melanogaster protein. Since the proteins have essentially identical domain structures, the corresponding genes form a distinct gene family. The possible link between TNKL and cancer justifies its further functional analysis

Ablation of TNF or lymphotoxin signaling and the frequency of spontaneous tumors in p53-deficient mice

TNF plays diverse and contrasting roles in cancer, promoting skin carcinogenesis and metastasis, but also possessing potent antitumor effects in mice. TNF via TNFR1 axis induces NFkappaB, and may contribute to inflammation-facilitated neoplasia. On the other hand, lymphomas are cited as rare complications of anti-TNF therapy in humans. In order to address possible modulating role of TNF and of a related cytokine, LTalpha, in spontaneous tumorigenesis, we compared mice with p53-TNF, p53-LTalpha, p53-TNFR1 and p53-TNF-LT combined deficiencies. Unexpectedly, neither of these mice showed significant modulation of their survival or shift in the spectrum of emerging tumors, as compared to p53-deficient mice, arguing against direct link between TNF blockade and lymphoma development

Engulfment of mast cell secretory granules on skin inflammation boosts dendritic cell migration and priming efficiency.

Background: Mast cells (MCs) are best known as key effector cells of allergic reactions, but they also play an important role in host defense against pathogens. Despite increasing evidence for a critical effect of MCs on adaptive immunity, the underlying mechanisms are poorly understood.Objective: Here we monitored MC intercellular communication with dendritic cells (DCs), MC activation, and degranulation and tracked the fate of exocytosed mast cell granules (MCGs) during skin inflammation.Methods: Using a strategy to stain intracellular MCGs in vivo, we tracked the MCG fate after skin inflammation-induced MC degranulation. Furthermore, exogenous MCGs were applied to MC-deficient mice by means of intradermal injection. MCG effects on DC functionality and adaptive immune responses in vivo were assessed by combining intravital multiphoton microscopy with flow cytometry and functional assays.Results: We demonstrate that dermal DCs engulf the intact granules exocytosed by MCs on skin inflammation. Subsequently, the engulfed MCGs are actively shuttled to skin-draining lymph nodes and finally degraded inside DCs within the lymphoid tissue. Most importantly, MCG uptake promotes DC maturation and migration to skin-draining lymph nodes, partially through MCderived TNF, and boosts their T-cell priming efficiency. Surprisingly, exogenous MCGs alone are sufficient to induce a prominent DC activation and T-cell response.Conclusion: Our study highlights a unique feature of peripheral MCs to affect lymphoid tissue-borne adaptive immunity over distance by modifying DC functionality through delivery of granule-stored mediators

Autonomous TNF is critical for in vivo monocyte survival in steady state and inflammation.

Monocytes are circulating mononuclear phagocytes, poised to extravasate to sites of inflammation and differentiate into monocyte-derived macrophages and dendritic cells. Tumor necrosis factor (TNF) and its receptors are up-regulated during monopoiesis and expressed by circulating monocytes, as well as effector monocytes infiltrating certain sites of inflammation, such as the spinal cord, during experimental autoimmune encephalomyelitis (EAE). In this study, using competitive in vitro and in vivo assays, we show that monocytes deficient for TNF or TNF receptors are outcompeted by their wild-type counterpart. Moreover, monocyte-autonomous TNF is critical for the function of these cells, as TNF ablation in monocytes/macrophages, but not in microglia, delayed the onset of EAE in challenged animals and was associated with reduced acute spinal cord infiltration of Ly6Chi effector monocytes. Collectively, our data reveal a previously unappreciated critical cell-autonomous role of TNF on monocytes for their survival, maintenance, and function

Crosstalk between keratinocytes and adaptive immune cells in an IkappaBalpha protein-mediated inflammatory disease of the skin.

Inflammatory diseases at epithelial borders develop from aberrant interactions between resident cells of the tissue and invading immunocytes. Here, we unraveled basic functions of epithelial cells and immune cells and the sequence of their interactions in an inflammatory skin disease. Ubiquitous deficiency of the I?B? protein (Ikba?/?) as well as concomitant deletion of Ikba specifically in keratinocytes and T cells (IkbaK5?/K5? lck?/lck?) resulted in an inflammatory skin phenotype that involved the epithelial compartment and depended on the presence of lymphocytes as well as tumor necrosis factor and lymphotoxin signaling. In contrast, mice with selective ablation of Ikba in keratinocytes or lymphocytes showed inflammation limited to the dermal compartment or a normal skin phenotype, respectively. Targeted deletion of RelA from epidermal keratinocytes completely rescued the inflammatory skin phenotype of Ikba?/? mice. This finding emphasizes the important role of aberrant NF-?B activation in both keratinocytes and lymphocytes in the development of the observed inflammatory skin changes

Macrophages acquire a TNF-dependent inflammatory memory in allergic asthma.

BACKGROUND: Infectious agents can reprogram or "train" macrophages and their progenitors to respond more readily to subsequent insults. However, whether such an inflammatory memory exists in type-2 inflammatory conditions such as allergic asthma was not known. OBJECTIVE: To decipher macrophage trained immunity in allergic asthma. METHODS: We used a combination of clinical sampling of house dust mite (HDM)-allergic patients, HDM-induced allergic airway inflammation (AAI) in mice and an in vitro training set-up to analyze persistent changes in macrophage eicosanoid-, cytokine- and chemokine production as well as underlying metabolic and epigenetic mechanisms. Transcriptional and metabolic profiles of patient-derived and in vitro trained macrophages were assessed by RNA sequencing or Seahorse and LC-MS/MS analysis, respectively. RESULTS: We found that macrophages differentiated from bone marrow- or blood monocyte- progenitors of HDM-allergic mice or asthma patients show inflammatory transcriptional reprogramming and excessive mediator (TNF-α, CCL17, leukotriene, PGE2, IL-6) responses upon stimulation. Macrophages from HDM-allergic mice initially exhibited a type-2 imprint, which shifted towards a classical inflammatory training over time. HDM-induced AAI elicited a metabolically activated macrophage phenotype, producing high amounts of 2-hydroxyglutarate (2-HG). HDM-induced macrophage training in vitro was mediated by a formyl-peptide receptor 2 (FPR2)-TNF-2-HG-PGE2/EP2-axis, resulting in an M2-like macrophage phenotype with high CCL17 production. TNF blockade by etanercept or genetic ablation of Tnf in myeloid cells prevented the inflammatory imprinting of bone marrow-derived macrophages from HDM-allergic mice. CONCLUSION: Allergen-triggered inflammation drives a TNF-dependent innate memory, which may perpetuate and exacerbate chronic type-2 airway inflammation and thus represents a target for asthma therapy