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Background: Although antibodies blocking immune checkpoints have already been approved for clinical cancer treatment, the mechanisms involved are not yet completely elucidated. Here we used a λ-MYC transgenic model of endogenously growing B-cell lymphoma to analyze the requirements for effective therapy with immune checkpoint inhibitors., Methods: Growth of spontaneous lymphoma was monitored in mice that received antibodies targeting programmed cell death protein 1 and cytotoxic T lymphocyte-associated protein-4, and the role of different immune cell compartments and cytokines was studied by in vivo depletion experiments. Activation of T and natural killer cells and the induction of tumor senescence were analyzed by flow cytometry., Results: On immune checkpoint blockade, visible lymphomas developed at later time points than in untreated controls, indicating an enhanced tumor control. Importantly, 20% to 30% of mice were even long-term protected and did never develop clinical signs of tumor growth. The therapeutic effect was dependent on cytokine-induced senescence in malignant B cells. The proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor (TNF) were necessary for the survival benefit as well as for senescence induction in the λ-MYC model. Antibody therapy improved T-cell functions such as cytokine production, and long-time survivors were only observed in the presence of T cells. Yet, NK cells also had a pronounced effect on therapy-induced delay of tumor growth. Antibody treatment enhanced numbers, proliferation and IFN-γ expression of NK cells in developing tumors. The therapeutic effect was fully abrogated only after depletion of both, T cells and NK cells, or after ablation of either IFN-γ or TNF., Conclusions: Tumor cell senescence may explain why patients responding to immune checkpoint blockade frequently show stable growth arrest of tumors rather than complete tumor regression. In the lymphoma model studied, successful therapy required both, tumor-directed T-cell responses and NK cells, which control, at least partly, tumor development through cytokine-induced tumor senescence., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background/aims: Cellular senescence, or permanent growth arrest, is known as an effective tumor suppressor mechanism that can be induced by different stressors, such as oncogenes, chemotherapeutics or cytokine cocktails. Previous studies demonstrated that the growth-repressing state of oncogene-induced senescent cells depends on argonaute protein 2 (Ago2)-mediated transcriptional gene silencing and Ago2/Rb corepression of E2F-dependent cell cycle genes. Cytokine-induced senescence (CIS) likewise depends on activation of the p16Ink4a/Rb pathway, and consecutive inactivation of the E2F family of transcription factors. In the present study, we therefore analyzed the role of Ago2 in CIS., Methods: Human cancer cell lines were treated with interferon-gamma (IFN-γ) and tumor necrosis factor (TNF) to induce senescence. Senescence was determined by growth assays and measurement of senescence-associated β-galactosidase (SA-β-gal) activity, Ago2 translocation by Ago2/ Ki67 immunofluorescence staining and western blot analysis, and gene transcription by quantitative polymerase chain reaction (qPCR)., Results: IFN-γ and TNF permanently stopped cell proliferation and time-dependently increased SA-β-gal activity. After 24 - 48 h of cytokine treatment, Ago2 translocated from the cytoplasm into the nucleus of Ki67-negative cells, an effect which was shown to be reversible. Importantly, the proinflammatory cytokine cocktail suppressed Ago2-regulated cell cycle control genes, and siRNA-mediated depletion of Ago2 interfered with cytokine-induced growth inhibition., Conclusion: IFN-γ and TNF induce a stable cell cycle arrest of cancer cells that is accompanied by a fast nuclear Ago2 translocation and repression of Ago2-regulated cell cycle control genes. As Ago2 downregulation impairs cytokine-induced growth regulation, Ago2 may contribute to tissue homeostasis in human cancers., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

The immune response is a first-line systemic defense to curb tumorigenesis and metastasis. Much effort has been invested to design antitumor interventions that would boost the immune system in its fight to defeat or contain cancerous growth. Tumor vaccination protocols, transfer of tumor-associated-antigen-specific T cells, T cell activity-regulating antibodies, and recombinant cytokines are counted among a toolbox filled with immunotherapeutic options. Although the mechanistic underpinnings of tumor immune control remain to be deciphered, these are studied with the goal of cancer cell destruction. In contrast, tumor dormancy is considered as a dangerous equilibrium between cell proliferation and cell death. There is, however, emerging evidence that tumor immune control can be achieved in the absence of overt cancer cell death. Here, we propose cytokine-induced senescence (CIS) by transfer of T helper-1 cells (T H 1) or by recombinant cytokines as a novel therapeutic intervention for cancer treatment. Immunity-induced senescence triggers a stable cell cycle arrest of cancer cells. It engages the immune system to construct defensive, isolating barriers around tumors, and prevents tumor growth through the delivery or induction of T H 1-cytokines in the tumor microenvironment. Keeping cancer cells in a non-proliferating state is a strategy, which directly copes with the lost homeostasis of aggressive tumors. As most studies show that even after efficient cancer therapies minimal residual disease persists, we suggest that therapies should include immune-mediated senescence for cancer surveillance. CIS has the goal to control the residual tumor and to transform a deadly disease into a state of silent tumor persistence.

Background and Objectives: The objective was to determine the diagnostic value of direct immunofluorescence (DIF) in ocular mucous membrane pemphigoid (ocular MMP), taking into account immunofluorescence patterns and biopsy sites., Patients and Methods: DIF results and medical records of 54 patients with a suspected diagnosis of ocular MMP were reviewed., Results: There was an overall prevalence of ocular MMP in 70.4 % of cases. Linear deposition of IgA, IgG, or C3 showed a high positive predictive value (84-100 %). Sensitivity and negative predictive value of IgG, IgM, IgG, and C3 in DIF were higher in cutaneous samples than in conjunctival biopsies, thus yielding a higher diagnostic accuracy. The sensitivity of DIF in ocular MMP seems to be lower than in bullous pemphigoid., Conclusions: The diagnostic value of DIF in the workup of ocular MMP was confirmed. However, biopsies taken from non-conjunctival, cutaneous tissue appear to yield more accurate results., (© 2015 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.)

Costimulatory surface molecules and instructive cytokines expressed by dendritic cells (DCs) determine the outcome of an immune response. In malignant disease, DCs are often functionally compromised. In most tumors studied so far, the deficient induction of effective T cell responses has been associated with a blockade of DC maturation, but little has been known on DCs infiltrating malignant B cell lymphoma. Here, we investigated for the first time the phenotypic and functional status of DCs in B cell lymphoma, and we analyzed the network of DCs, tumor cells, natural killer (NK) cells and cytokines present in the tumor micromilieu. Therefor, we used an endogenous myc-transgenic mouse lymphoma model, because transplanted tumor cells foster an IFN-γ-driven Th1 antitumor response rather than an immunosuppressive environment, which is observed in autochthonous neoplasias. Lymphoma-infiltrating DCs showed a mature phenotype and a Th2-inducing cytokine pattern. This situation is in contrast to most human malignancies and mouse models described. Cellular contacts between DCs and tumor cells, which involved CD62L on the lymphoma, caused upregulation of costimulatory molecules, whereas IL-10 primarily derived from lymphoma cells induced an IL-12/IL-10 shift in DCs. Thus, alteration of costimulatory molecules and instructive cytokines was mediated by distinct mechanisms. Normal NK cells were able to additionally modulate DC maturation but this effect was absent in the lymphoma environment where IFN-γ production by NK cells was severely impaired. These data are relevant for establishing novel immunotherapeutic approaches against B cell lymphoma.

Cancer control by adaptive immunity involves a number of defined death and clearance mechanisms. However, efficient inhibition of exponential cancer growth by T cells and interferon-γ (IFN-γ) requires additional undefined mechanisms that arrest cancer cell proliferation. Here we show that the combined action of the T-helper-1-cell cytokines IFN-γ and tumour necrosis factor (TNF) directly induces permanent growth arrest in cancers. To safely separate senescence induced by tumour immunity from oncogene-induced senescence, we used a mouse model in which the Simian virus 40 large T antigen (Tag) expressed under the control of the rat insulin promoter creates tumours by attenuating p53- and Rb-mediated cell cycle control. When combined, IFN-γ and TNF drive Tag-expressing cancers into senescence by inducing permanent growth arrest in G1/G0, activation of p16INK4a (also known as CDKN2A), and downstream Rb hypophosphorylation at serine 795. This cytokine-induced senescence strictly requires STAT1 and TNFR1 (also known as TNFRSF1A) signalling in addition to p16INK4a. In vivo, Tag-specific T-helper 1 cells permanently arrest Tag-expressing cancers by inducing IFN-γ- and TNFR1-dependent senescence. Conversely, Tnfr1(-/-)Tag-expressing cancers resist cytokine-induced senescence and grow aggressively, even in TNFR1-expressing hosts. Finally, as IFN-γ and TNF induce senescence in numerous murine and human cancers, this may be a general mechanism for arresting cancer progression.

Psoriasis is a T cell-dependent autoimmune disease of the skin and joints. Disease manifestation is orchestrated by proinflammatory CD4-positive T helper cells producing either interferon-gamma (Th1) or interleukin (IL)-17 (Th17). These Th1 and Th17 cells interact with dermal dendritic cells, macrophages, mast cells, and neutrophils. Together, they cause an inflammation that mainly involves interferon-gamma, tumor necrosis factor, IL-8, IL-12, IL-17, IL-19, and IL-23. New therapeutics either are directed against T cells, tumor necrosis factor, and IL-12/IL-23 or deviate immune responses into a protective IL-4-dominated Th2 phenotype.

Rapid production of IL-4 by Leishmania homolog of mammalian RACK1 (LACK)-reactive CD4(+) T cells expressing the V beta 4-V alpha 8 TCR chains has been shown to drive aberrant Th2 cell development and susceptibility to Leishmania major in BALB/c mice. In contrast, mice from resistant strains fail to express this early IL-4 response. However, administration of either anti-IL-12 or -IFN-gamma at the initiation of infection allows the expression of this early IL-4 response in resistant mice. In this work we show that Leishmania homolog of mammalian RACK1-reactive CD4(+) T cells also expressing the V beta 4-V alpha 8 TCR chains are the source of the early IL-4 response to L. major in resistant mice given anti-IL-12 or -IFN-gamma Abs only at the onset of infection. Strikingly, these cells were found to be required for the reversal of the natural resistance of C57BL/6 mice following a single administration of anti-IL-12 or -IFN-gamma Abs. Together these results suggest that a deficiency in mechanisms capable of down-regulating the early IL-4 response to L. major contributes to the exquisite susceptibility of BALB/c mice to L. major.

The aim is to unravel the mechanism of mesalazine (5-ASA) on proinflammatory cytokines in PBMCs of patients with HLA-B27 +and HLA-B27 -acute anterior uveitis (AAU), and whether this may explain the different effects of 5-ASA in both disoders. PBMCs from 12 HLA-B27+ and 4 HLA-B27- AAU patients were preincubated with 5-ASA and stimulated with LPS. As mesalazine (5-ASA) could be involved in ER stress, proinflammatory and ER stress-associated cytokines and markers were measured. Mesalazine (5-ASA) suppressed IL-6 mRNA in healthy donors and in HLA-B27+ and HLA-B27- patients but did not lead to induction and secretion of IL-1β. In HLA-B27 + or – patients the ER stress-associated markers CHOP (DDIT3) and ATF6 were suppressed. Here we show that mesalazine (5-ASA) inhibits the transcription of proinflammatory and (ER) stress associated cytokines and markers, independently of the HLA-B27 status. Results show the similarities of both AAU types but do not decipher the mechanism why the HLA-B27 status determines the therapeutic response to mesalazine in AAU. [ABSTRACT FROM AUTHOR]

Abstract: Staphylococcus epidermidis colonises human skin without apparent inflammation, but a dominance of S. epidermidis and S. aureus is characteristic of cutaneous microbial dysbiosis in atopic dermatitis (AD). While S. aureus can trigger AD, the role of S. epidermidis is less understood. We characterised consequences of innate immune sensing of lipoteichoic acid (LTA) preparations derived from S. epidermidis (epi‐LTA) or S. aureus (aureus‐LTA). Therefore, dendritic cell (DC) activation and consecutive priming of antigen‐specific T cells following exposure of DC to epi‐LTA or aureus‐LTA were investigated. Mimicking acute AD, exposure of DC to IL‐4 and LTAs was analysed. Exposure to epi‐LTA or aureus‐LTA activated human immune cells and murine dendritic cells (DCs) via TLR2/MyD88, however, resulting in divergent immune profiles. Differences between LTAs were significant for IL‐6, IL‐12p40 and IL‐12p70 but not for IL‐10, which was best reflected by the IL‐12p70‐to‐IL‐10 ratio being IL‐10‐balanced for epi‐LTA but pro‐inflammatory for aureus‐LTA. LTA‐exposed DCs activated CD4+ T cells; however, while T‐cell‐derived IL‐10 was equivalent between LTAs, IFN‐γ and IL‐17 were significantly higher for aureus‐LTA. Mimicking acute AD by exposing DCs to IL‐4 and LTAs revealed that IL‐4 significantly and uniformly suppressed epi‐LTA‐induced cytokine production, keeping the IL‐12p70‐to‐IL‐10 ratio balanced. In contrast, exposure of DCs to aureus‐LTA and IL‐4 enhanced IL‐12p70 but suppressed IL‐10 levels, further unbalancing the IL‐12p70‐to‐IL‐10 ratio. These data demonstrate opposing immune consequences following exposure to staphylococcal LTAs. Epi‐LTA induced IL‐10‐balanced, aureus‐LTA pro‐inflammatory immune profiles. [ABSTRACT FROM AUTHOR]

As one of the largest organs, the skin forms a mechanical and immunological barrier to the environment. The skin immune system harbors cells of the innate immune system and cells of the adaptive immune system. Signals of the innate immune system typically initiate skin immune responses, while cells and cytokines of the adaptive immune system perpetuate the inflammation. Skin immune responses ensure effective host defense against pathogens but can also cause inflammatory skin diseases. An extensive crosstalk between the different cell types of the immune system, tissue cells, and pathogens is responsible for the complexity of skin immune reactions. Here we summarize the major cellular and molecular components of the innate and adaptive skin immune system. [ABSTRACT FROM AUTHOR]

Psoriasis pathogenesis is closely associated with disease-inducing Th1 and Th17 cells. Yet, several studies suggest that aberrant keratinocyte or endothelial cell signalling significantly contributes to disease manifestation. Histological hallmarks of psoriatic skin include the infiltration of multiple immune cells, keratinocyte proliferation and increased dermal vascularity. Formation of new blood vessels starts with early psoriatic changes and disappears with disease clearance. Several angiogenic mediators like vascular endothelial growth factor, hypoxia-inducible factors, angiopoietins and pro-angiogenic cytokines, such as tumour necrosis factor (TNF), interleukin (IL)-8 and IL-17, are up-regulated in psoriasis development. Contact- and mediator-dependent factors derived from keratinocytes, mast cells and immune cells may contribute to the strong blood vessel formation of psoriasis. New technologies and experimental models provide new insights into the role of angiogenesis in psoriasis pathogenesis. Interestingly, many therapies target not only immune cells, but also protein structures of endothelial cells. Here we summarize the role of pro-angiogenic factors in psoriasis development and discuss angiogenesis as a potential target of novel therapies. [ABSTRACT FROM AUTHOR]

Through the release of distinct sets of cytokines, Th1 and Th2 cells exert characteristic and often mutually exclusive or antagonistic immune effector functions. In the present report, we document and discuss several findings on the induction mechanisms of these cellular subtypes and present recent findings on their respective functions in vivo. The preferential induction of Th1 or Th2 cytokine patterns in mature CD4+ T cells is generally attributed to the action of cytokines. In addition, there is evidence that prolonged T-cell receptor occupancy may induce the development of the Th2 phenotype. Prolonged occupancy of the T-cell receptor provides enough autocrine interleukin-4 to permit induction of the Th2 phenotype. Both Th1 and Th2 cells may be derived from a single mature CD4+ T cell, providing strong evidence for post-thymic modulation of the T-cell cytokine profile and rendering the possibility of predetermined cytokine patterns in T cells unlikely. CD4+ Th1 cells mediate the tumor necrosis factor- and interferon-γ-dependent classic delayed type hypersensitivity reaction. We found that Th2 cells were also capable of mediating local inflammatory reactions that depended on their prototypic lymphokine interleukin-4, and, in high tumor necrosis factor-α. Both Th-cell subsets induced cellular infiltrates that were not distinguishable on histologic grounds. In contrast to the widely accepted belief that only Th1 cells can mediate delayed hypersensitivity reactions, our results demonstrate that T cells with either lymphokine profile can cause tissue inflammation with leukocytic infiltrates. [ABSTRACT FROM AUTHOR]

The inflammasome is a protein complex cleaving the pro-inflammatory cytokines IL-1β and IL-18 into their active forms by caspase-1 activation. The cytosolic protein complex can be activated by danger signals, such as bacterial and viral components, ATP, or uric acid crystals, and reacts as a sensor of innate immunity. In the skin, sensitizing agents promote induction of specific T-cell-mediated contact hypersensitivity. They induce dendritic cell migration, a precondition for the priming of specific T cells. They are a prerequisite for the recruitment of cells into the skin that demand pro-inflammatory stimuli, such as IL-1β and IL-18. Watanabe et al. (2007, this issue) demonstrate the presence of the inflammasome complex in keratinocytes and report that this complex can be activated by contact sensitizers, such as trinitrocholorobenzene (TNCB), both in vitro and in vivo. The study documents a regulatory effect of innate immunity in a T-cell-mediated delayed-type hypersensitivity reaction.Journal of Investigative Dermatology (2007) 127, 1853–1855. doi:10.1038/sj.jid.5700815 [ABSTRACT FROM AUTHOR]

Background Chronic inflammatory skin diseases are characterized by controlled proliferation of keratinocytes. Here, activating transcription factor 3 (ATF3) might play a fundamental role. In these inflammatory diseases, proliferation is controlled and only rarely leads to cancer development which can be supported by an inflammatory microenvironment. ATF3 is a dual function protein as it suppresses pro-inflammatory IL-6 and IL-8, but also acts as a pro-oncogenic factor by the suppression of p53. We therefore analyzed ATF3 expression comparing myeloid cells with keratinocytes. Objective To dissect the bi-modal role of ATF3 we pharmacologically induced ATF3 and analyzed its influence on cytokine expression and secretion in a cell type specific manner. Methods Since inflammatory skin diseases can be treated systemically with Cyclosporin A or Dimethylfumarate we stimulated myeloid cells and primary human keratinocytes with these drugs and analyzed gene expression by quantitative real-time PCR. Cytokine secretion was measured by ELISA. Results In the present study, we could show that ATF3 is induced in PBMCs by DMF and weakly by Ebselen, while CsA is the most prominent inducer of ATF3 in keratinocytes without enhancing HO-1 transcription. Further we could show that induction of stress by LPS treatment elevates IL-1β and IL-6 and weakly ATF3 transcription in PBMCs. While transcription of both cytokines is elevated, LPS treatment mediates IL-6 secretion with only little IL-1β secretion. Treatment with DMF dampens LPS-induced transcription. Conclusions Taken together, our results shed light into the different carcinogenic potential of CsA and DMF, which both target ATF3. Collectively our data demonstrate that CsA strongly induces pro-carcinogenic ATF3 in keratinocytes, whereas ATF3 induction by DMF in myeloid cells acts anti-inflammatory. [ABSTRACT FROM AUTHOR]

Background Atopic dermatitis (AD) is a common inflammatory skin disease with dysfunction of the skin barrier, an abnormal immune response and frequent allergies to environmental antigens like food antigens. Clinical observations suggest that certain diets can influence the course of AD. Objective Here we compared the phenotype of food allergen-specific T cells activated through skin or gut allergen exposure to transfer skin inflammation into naïve recipients upon epicutaenous allergen challenge. Methods Ovalbumin (OVA) TCR-transgenic mice were treated epicutaneously with OVA or were fed OVA. CD4 + T cells from skin lymph nodes or mesenteric lymph nodes were transferred into naïve BALB/c mice, which were challenged with OVA epicutaneously. Skin inflammation was determined by histological parameters. In addition, we analyzed the phenotype of the immune response in lymphoid tissues and in skin tissue. Results TCR-transgenic T cells activated through epicutaneous or oral OVA exposure both migrate to skin lymph nodes after adoptive transfer and epicutaenous OVA exposure. AD-like skin inflammation could only be induced by the transfer of epicutaneously primed OVA T cells. Analysis of the immune phenotype demonstrated an IL-22/IL-17A-dominated immune phenotype of skin-pathogenic T cells. Conclusion IL-22 seems to be the critical cytokine for the development of AD and is induced in this model by epicutaneous sensitization with OVA. [ABSTRACT FROM AUTHOR]