Ioanna Evdokia Galani
@bioacademy.gr
Center for Clinical, Experimental Surgery, & Translational Research
Biomedical Research Foundation of the Academy of Athens (BRFAA)
RESEARCH INTERESTS
Immunology, Respiratory viral infections
Scopus Publications
Scopus Publications
Georgios Divolis, Evgenia Synolaki, Athanasia Doulou, Ariana Gavriil, Christina C. Giannouli, Anastasia Apostolidou, Martyn L. Foster, Martin M. Matzuk, Panagiotis Skendros, Ioanna-Evdokia Galani,et al.
Frontiers Media SA
BackgroundPre-neutrophils, while developing in the bone marrow, transcribe the Inhba gene and synthesize Activin-A protein, which they store and release at the earliest stage of their activation in the periphery. However, the role of neutrophil-derived Activin-A is not completely understood.MethodsTo address this issue, we developed a neutrophil-specific Activin-A-deficient animal model (S100a8-Cre/Inhbafl/fl mice) and analyzed the immune response to Influenza A virus (IAV) infection. More specifically, evaluation of body weight and lung mechanics, molecular and cellular analyses of bronchoalveolar lavage fluids, flow cytometry and cell sorting of lung cells, as well as histopathological analysis of lung tissues, were performed in PBS-treated and IAV-infected transgenic animals.ResultsWe found that neutrophil-specific Activin-A deficiency led to exacerbated pulmonary inflammation and widespread hemorrhagic histopathology in the lungs of IAV-infected animals that was associated with an exuberant production of neutrophil extracellular traps (NETs). Moreover, deletion of the Activin-A receptor ALK4/ACVR1B in neutrophils exacerbated IAV-induced pathology as well, suggesting that neutrophils themselves are potential targets of Activin-A-mediated signaling. The pro-NETotic tendency of Activin-A-deficient neutrophils was further verified in the context of thioglycollate-induced peritonitis, a model characterized by robust peritoneal neutrophilia. Of importance, transcriptome analysis of Activin-A-deficient neutrophils revealed alterations consistent with a predisposition for NET release. ConclusionCollectively, our data demonstrate that Activin-A, secreted by neutrophils upon their activation in the periphery, acts as a feedback mechanism to moderate their pro-NETotic tendency and limit the collateral tissue damage caused by neutrophil excess activation during the inflammatory response.
Eleni Siouti, Maria Salagianni, Maria Manioudaki, Eleftherios Pavlos, Apostolos Klinakis, Ioanna‐Evdokia Galani, and Evangelos Andreakos
Wiley
AbstractThe importance of macrophages in adipose tissue (AT) homeostasis and inflammation is well established. However, the potential cues that regulate their function remain incompletely understood. To bridge this important gap, we sought to characterize novel pathways involved using a mouse model of diet‐induced obesity. By performing transcriptomics analysis of AT macrophages (ATMs), we found that late‐stage ATMs from high‐fat diet mice presented with perturbed Notch signaling accompanied by robust proinflammatory and metabolic changes. To explore the hypothesis that the deregulated Notch pathway contributes to the development of AT inflammation and diet‐induced obesity, we employed a genetic approach to abrogate myeloid Notch1 and Notch2 receptors. Our results revealed that the combined loss of Notch1 and Notch2 worsened obesity‐related metabolic dysregulation. Body and AT weight gain was higher, blood glucose levels increased and metabolic parameters were substantially worsened in deficient mice fed high‐fat diet. Moreover, serum insulin and leptin were elevated as were triglycerides. Molecular analysis of ATMs showed that deletion of Notch receptors escalated inflammation through the induction of an M1‐like pro‐inflammatory phenotype. Our findings thus support a protective role of myeloid Notch signaling in adipose tissue inflammation and metabolic dysregulation.
Sotirios Kotsovilis, Maria Salagianni, Aimilia Varela, Constantinos H. Davos, Ioanna E. Galani, and Evangelos Andreakos
MDPI AG
Apolipoprotein E-knockout (Apoe-/-) mice constitute the most widely employed animal model of atherosclerosis. Deletion of Apoe induces profound hypercholesterolemia and promotes the development of atherosclerosis. However, despite its widespread use, the Apoe-/- mouse model remains incompletely characterized, especially at late time points and advanced disease stages. Thus, it is unclear how late atherosclerotic plaques compare to earlier ones in terms of lipid deposition, calcification, macrophage accumulation, smooth muscle cell presence, or plaque necrosis. Additionally, it is unknown how cardiac function and hemodynamic parameters are affected at late disease stages. Here, we used a comprehensive analysis based on histology, fluorescence microscopy, and Doppler ultrasonography to show that in normal chow diet-fed Apoe-/- mice, atherosclerotic lesions at the level of the aortic valve evolve from a more cellular macrophage-rich phenotype at 26 weeks to an acellular, lipid-rich, and more necrotic phenotype at 52 weeks of age, also marked by enhanced lipid deposition and calcification. Coronary artery atherosclerotic lesions are sparse at 26 weeks but ubiquitous and extensive at 52 weeks; yet, left ventricular function was not significantly affected. These findings demonstrate that atherosclerosis in Apoe-/- mice is a highly dynamic process, with atherosclerotic plaques evolving over time. At late disease stages, histopathological characteristics of increased plaque vulnerability predominate in combination with frequent and extensive coronary artery lesions, which nevertheless may not necessarily result in impaired cardiac function.
Efthymia Theofani, Maria Semitekolou, Konstantinos Samitas, Annie Mais, Ioanna E. Galani, Vasiliki Triantafyllia, Joanna Lama, Ioannis Morianos, Athanasios Stavropoulos, Se‐Jin Jeong,et al.
Wiley
Ogan K. Kumova, Ioanna-Evdokia Galani, Abhishek Rao, Hannah Johnson, Vasiliki Triantafyllia, Stephanie M. Matt, Judy Pascasio, Peter J. Gaskill, Evangelos Andreakos, Peter D. Katsikis,et al.
Springer Science and Business Media LLC
Sofia Tagkareli, Maria Salagianni, Ioanna‐Evdokia Galani, Maria Manioudaki, Eleftherios Pavlos, Kalliopi Thanopoulou, and Evangelos Andreakos
Wiley
BACKGROUND
Although FoxP3+ regulatory T (Treg) cells constitute a highly heterogeneous population, with different regulatory potential depending on the disease context, distinct subsets or phenotypes remain poorly defined. This hampers the development of immunotherapy for allergic and autoimmune disorders. The present study aimed at characterizing distinct FoxP3+ Treg subpopulations involved in the suppression of Th2-mediated allergic inflammation in the lung.
METHODS
We used an established mouse model of allergic airway disease based on ovalbumin sensitization and challenge to analyze FoxP3+ Tregs during the induction and resolution of inflammation, and identify markers that distinguish their most suppressive phenotypes. We also developed a new knock-in mouse model (Foxp3cre Cd103dtr ) enabling the specific ablation of CD103+ FoxP3+ Tregs for functional studies.
RESULTS
We found that during resolution of allergic airway inflammation in mice >50% of FoxP3+ Treg cells expressed the integrin CD103 which marks FoxP3+ Treg cells of high IL-10 production, increased expression of immunoregulatory molecules such as KLRG1, ICOS and CD127, and enhanced suppressive capacity for Th2-mediated inflammatory responses. CD103+ FoxP3+ Tregs were essential for keeping allergic inflammation under control as their specific depletion in Foxp3cre Cd103dtr mice lead to severe alveocapillary damage, eosinophilic pneumonia, and markedly reduced lifespan of the animals. Conversely, adoptive transfer of CD103+ FoxP3+ Tregs effectively treated disease, attenuating Th2 responses and allergic inflammation in an IL-10-dependent manner.
CONCLUSIONS
Our study identifies a novel regulatory T cell population, defined by CD103 expression, programmed to prevent exuberant type 2 inflammation and keep homeostasis in the respiratory tract under control. This has important therapeutic implications.
Ioanna-Evdokia Galani, Vasiliki Triantafyllia, Evridiki-Evangelia Eleminiadou, and Evangelos Andreakos
Elsevier BV
Ioanna-Evdokia Galani and Evangelos Andreakos
Elsevier BV
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a recently emerged pathogen that has caused coronavirus disease 2019 (COVID-19), the worst pandemic of our times leading to tremendous loss of human life and unprecedented measures of social distancing. COVID-19 symptom manifestations range from asymptomatic disease to severe and lethal outcomes. Lack of previous exposure and immunity to SARS-CoV-2, and high infectivity of the virus have contributed to its broad spread across the globe. In the absence of specific adaptive immunity, innate immune mechanisms are crucial for efficient antiviral defenses and control of the infection. Accumulating evidence now suggests that the remarkable heterogeneity in COVID-19 disease manifestations is due to variable degrees of impairment of innate immune mechanisms. In this review, we summarize recent findings describing both viral and host intrinsic factors that have been linked to defective innate immune responses and account for severe COVID-19. We also discuss emerging therapeutic opportunities for targeting innate immunity for the treatment of COVID-19.
Ioanna-Evdokia Galani, Nikoletta Rovina, Vicky Lampropoulou, Vasiliki Triantafyllia, Maria Manioudaki, Eleftherios Pavlos, Evangelia Koukaki, Paraskevi C. Fragkou, Vasiliki Panou, Vasiliki Rapti,et al.
Springer Science and Business Media LLC
A central paradigm of immunity is that interferon (IFN)-mediated antiviral responses precede pro-inflammatory ones, optimizing host protection and minimizing collateral damage 1 , 2 . Here, we report that for coronavirus disease 2019 (COVID-19) this paradigm does not apply. By investigating temporal IFN and inflammatory cytokine patterns in 32 moderate-to-severe patients with COVID-19 hospitalized for pneumonia and longitudinally followed for the development of respiratory failure and death, we reveal that IFN-λ and type I IFN production were both diminished and delayed, induced only in a fraction of patients as they became critically ill. On the contrary, pro-inflammatory cytokines such as tumor necrosis factor (TNF), interleukin (IL)-6 and IL-8 were produced before IFNs in all patients and persisted for a prolonged time. This condition was reflected in blood transcriptomes wherein prominent IFN signatures were only seen in critically ill patients who also exhibited augmented inflammation. By comparison, in 16 patients with influenza (flu) hospitalized for pneumonia with similar clinicopathological characteristics to those of COVID-19 and 24 nonhospitalized patients with flu with milder symptoms, IFN-λ and type I IFN were robustly induced earlier, at higher levels and independently of disease severity, whereas pro-inflammatory cytokines were only acutely produced. Notably, higher IFN-λ concentrations in patients with COVID-19 correlated with lower viral load in bronchial aspirates and faster viral clearance and a higher IFN-λ to type I IFN ratio correlated with improved outcome for critically ill patients. Moreover, altered cytokine patterns in patients with COVID-19 correlated with longer hospitalization and higher incidence of critical disease and mortality compared to flu. These data point to an untuned antiviral response in COVID-19, contributing to persistent viral presence, hyperinflammation and respiratory failure. Andreakos and colleagues provide a longitudinal study comparing patients with COVID-19 to patients infected with influenza. They report a dysregulated interferon response whereby IFN-λ and type I IFN production were diminished and delayed in patients with COVID-19, exhibiting a response that is ‘untuned’ with other inflammatory cytokines.
Ioanna E. Galani, Eynav Klechevsky, and Evangelos Andreakos
Springer Science and Business Media LLC
Internationally renowned scientists gathered at the 2nd Human & Translational Immunology Conference in Kos, Greece, to discuss the latest advances in translational immunology, especially vaccinology, infectious diseases and tumor immunotherapy.
Evangelos Andreakos, Ivan Zanoni, and Ioanna E Galani
Elsevier BV
Lambda interferons (IFNλs, type III IFNs or interleukins-28/29) were described fifteen years ago as novel cytokines sharing structural and functional homology with IL-10 and type I IFNs, respectively. IFNλs engage a unique receptor complex comprising IFNLR1 and IL10R2, nevertheless they share signaling cascade and many functions with type I IFNs, questioning their possible non-redundant roles and overall biological importance. Here, we review the latest evidence establishing the primacy of IFNλs in front line protection at anatomical barriers, mediating antiviral immunity before type I IFNs. We also discuss their emerging role in regulating inflammation and limiting host damage, a major difference to type I IFNs. IFNλs come thus to light as dual function cytokines mediating antiviral immunity and damage control.
Evangelos Andreakos, Maria Salagianni, Ioanna E. Galani, and Ourania Koltsida
Frontiers Media SA
Type III interferons (IFNs), also termed lambda IFNs (IFNλs) or interleukins-28/29, constitute a new addition to the IFN family. They are induced upon infection and are particularly abundant at barrier surfaces, such as the respiratory and gastrointestinal tracts. Although they signal through a unique heterodimeric receptor complex comprising IFNLR1 and IL10RB, they activate a downstream signaling pathway remarkably similar to that of type I IFNs and share many functions with them. Yet, they also have important differences which are only now starting to unfold. Here, we review the current literature implicating type III IFNs in the regulation of immunity and homeostasis in the respiratory tract. We survey the common and unique characteristics of type III IFNs in terms of expression patterns, cellular targets, and biological activities and discuss their emerging role in first line defenses against respiratory viral infections. We further explore their immune modulatory functions and their involvement in the regulation of inflammatory responses during chronic respiratory diseases, such as asthma and chronic obstructive pulmonary disease. Type III IFNs are, therefore, arising as front-line guardians of immune defenses in the respiratory tract, fine tuning inflammation, and as potential novel therapeutics for the treatment of diverse respiratory diseases, including influenza virus infection and asthma.
Akrivi Chrysanthopoulou, Konstantinos Kambas, Dimitrios Stakos, Ioannis Mitroulis, Alexandros Mitsios, Veroniki Vidali, Iliana Angelidou, Magdalena Bochenek, Stella Arelaki, Athanasios Arampatzioglou,et al.
Wiley
Neutrophils and neutrophil‐released meshwork structures termed neutrophil extracellular traps (NETs) are major mediators of thromboinflammation and emerging targets for therapy, yet the mechanisms and pathways that control the role of neutrophils in thromboinflammation remain poorly understood. Here, we explored the role of IFN‐λ1/IL‐29, a major antiviral cytokine recently shown to suppress the neutrophil migratory capacity, in prothrombotic and proNETotic functions of neutrophils. In an ex vivo human experimental setting of acute ST‐segment elevation myocardial infarction (STEMI), we show that IFN‐λ1/IL‐29 hinders NET release and diminishes the amount of cytoplasmic TF in neutrophils. Since platelet–neutrophil interaction plays a major role in NET‐induced thromboinflammation, we further studied how IFN‐λ1/IL‐29 may interrupt this interaction. In this context, we identified inorganic polyphosphate (polyP) as a platelet‐derived NET inducer in STEMI. In arterial STEMI thrombi, polyP was present in platelets and in close proximity to NET remnants. PolyP release from activated platelets was dependent on thrombin present in infarcted artery plasma, resulting in NET formation by promoting mTOR inhibition and autophagy induction. The effect of polyP on mTOR inhibition was counteracted by IFN‐λ1/IL‐29 treatment, leading to inhibition of NET formation. Consistently, we show in an in vivo model of FeCl3‐induced arterial thrombosis that IFN‐λ2/IL‐28A exerts strong antithrombotic potential. Taken together, these findings reveal a novel function of IFN‐λ1/IL‐29 in the suppression of thromboinflammation. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Ioanna E. Galani, Vasiliki Triantafyllia, Evridiki-Evangelia Eleminiadou, Ourania Koltsida, Athanasios Stavropoulos, Maria Manioudaki, Dimitris Thanos, Sean E. Doyle, Sergei V. Kotenko, Kalliopi Thanopoulou,et al.
Elsevier BV
Summary Lambda interferons (IFN&lgr;s) or type III IFNs share homology, expression patterns, signaling cascades, and antiviral functions with type I IFNs. This has complicated the unwinding of their unique non‐redundant roles. Through the systematic study of influenza virus infection in mice, we herein show that IFN&lgr;s are the first IFNs produced that act at the epithelial barrier to suppress initial viral spread without activating inflammation. If infection progresses, type I IFNs come into play to enhance viral resistance and induce pro‐inflammatory responses essential for confronting infection but causing immunopathology. Central to this are neutrophils which respond to both cytokines to upregulate antimicrobial functions but exhibit pro‐inflammatory activation only to type I IFNs. Accordingly, Ifnlr1−/− mice display enhanced type I IFN production, neutrophilia, lung injury, and lethality, while therapeutic administration of PEG‐IFN&lgr; potently suppresses these effects. IFN&lgr;s therefore constitute the front line of antiviral defense in the lung without compromising host fitness. Graphical Abstract Figure. No Caption available. HighlightsIFN&lgr;s are the first IFNs produced that suppress initial viral spreadIFN&lgr;s exhibit potent antiviral functions without activating inflammationType I IFNs come up later to enhance antiviral and pro‐inflammatory responsesIFN&lgr;s and type I IFNs ensure optimal viral clearance with minimal collateral damage &NA; The importance of IFN&lgr;s in the respiratory tract remains puzzling. Galani and colleagues show that IFN&lgr;s provide front‐line antiviral protection without activating inflammation. When infection escapes IFN&lgr; control, type I IFNs come into play to enhance antiviral defenses and trigger pro‐inflammatory responses essential for confronting infection but causing immunopathology.
I. E. Galani and E. Andreakos
Wiley
Neutrophils are the first immune cell population recruited to sites of infection, including viral infections, and exhibit both protective and pathologic functions. In antibacterial and antifungal immunity, the role of neutrophils is well defined. However, in antiviral immunity, much less is known. Conventional wisdom suggests that neutrophils enhance antiviral defenses, yet evidence for that is limited. Interaction with other immune cell populations, virus internalization and killing, the release of cytokines, chemokines, and antimicrobial components are all mechanisms by which neutrophils can contribute to pathogen clearance. NET formation, extensively studied during bacterial infection, can further mediate antiviral defense by trapping and inactivating virus. In the present review, we discuss the current understanding of the complex role of neutrophil immunity in viral infections and disease pathogenesis and the potential mechanisms identified to date. We pinpoint the importance of a finely tuned neutrophilic response for achieving effective immune protection while avoiding detrimental tissue damage that can form the basis for the development of novel therapeutics.
Ioanna E. Galani, Ourania Koltsida, and Evangelos Andreakos
Springer International Publishing
Lambda interferons (IFN-λs), type III interferons or interleukins 28 and 29 are the latest addition to the class II cytokine family. They share low homology with the interferon (IFN) and IL-10 cytokine families, yet they exhibit common and unique activities, the full spectrum of which still remains incompletely understood. Although initially described for their antiviral functions, it is now appreciated that IFN-λs also mediate diverse antitumor and immune-modulatory effects, and are key determinants of innate immunity at mucosal sites such as the gastrointestinal and respiratory tracks. Here, we are reviewing the biological functions of IFN-λs, the mechanisms controlling their expression, their downstream effects and their role in the maintenance of homeostasis and disease. We are also exploring the potential application of IFN-λs as novel therapeutics.
Eleni Litsiou, Maria Semitekolou, Ioanna Galani, Ioannis Morianos, Aikaterini Tsoutsa, Panagiota Kara, Dimitra Rontogianni, Ion Bellenis, Maria Konstantinou, Konstantinos Potaris,et al.
American Thoracic Society
Eleni Litsiou, Maria Semitekolou, Ioanna E. Galani, Ioannis Morianos, Aikaterini Tsoutsa, Panagiota Kara, Dimitra Rontogianni, Ion Bellenis, Maria Konstantinou, Konstantinos Potaris,et al.
American Thoracic Society
RATIONALE
Little is known about what drives the appearance of lymphoid follicles (LFs), which may function as lymphoid organs in chronic obstructive pulmonary disease (COPD). In animal infection models, pulmonary LF formation requires expression of homeostatic chemokines by stromal cells and dendritic cells, partly via lymphotoxin.
OBJECTIVES
To study the role of homeostatic chemokines in LF formation in COPD and to identify mechanism(s) responsible for their production.
METHODS
Peripheral lung homeostatic chemokine and lymphotoxin expression were visualized by immunostainings and quantified by ELISA/quantitative reverse transcriptase-polymerase chain reaction in patients with COPD with and without LFs. Expression of lymphotoxin and homeostatic chemokine receptors was investigated by flow cytometry. Primary lung cell cultures, followed by ELISA/quantitative reverse transcriptase-polymerase chain reaction/flow cytometry, were performed to identify mechanisms of chemokine expression. Polycarbonate membrane filters were used to assess primary lung cell migration toward lung homogenates.
MEASUREMENTS AND MAIN RESULTS
LFs expressed the homeostatic chemokine CXCL13. Total CXCL13 levels correlated with LF density. Lung B cells of patients with COPD were important sources of CXCL13 and lymphotoxin and also expressed their receptors. Cigarette smoke extract, H2O2, and LPS exposure up-regulated B cell-derived CXCL13. The LPS-induced increase in CXCL13 was partly mediated via lymphotoxin. Notably, CXCL13 was required for efficient lung B-cell migration toward COPD lung homogenates and induced lung B cells to up-regulate lymphotoxin, which further promoted CXCL13 production, establishing a positive feedback loop.
CONCLUSIONS
LF formation in COPD may be driven by lung B cells via a CXCL13-dependent mechanism that involves toll-like receptor and lymphotoxin receptor signaling.
Maria Salagianni, Ioanna E. Galani, Anna M. Lundberg, Constantinos H. Davos, Aimilia Varela, Ariana Gavriil, Leo-Pekka Lyytikäinen, Terho Lehtimäki, Fragiska Sigala, Lasse Folkersen,et al.
Ovid Technologies (Wolters Kluwer Health)
Background Toll-like receptors (TLRs) have long been considered to be major culprits in the development of atherosclerosis, contributing both to its progression and clinical complications. However, evidence for most TLRs beyond TLR2 and TLR4 is lacking. Methods and Results We used experimental mouse models, human atheroma cultures, and well-established human biobanks to investigate the role of TLR7 in atherosclerosis. We report the unexpected finding that TLR7, a receptor recognizing self–nucleic acid complexes, is protective in atherosclerosis. In Apoe−/− mice, functional inactivation of TLR7 resulted in accelerated lesion development, increased stenosis, and enhanced plaque vulnerability as revealed by Doppler ultrasound and/or histopathology. Mechanistically, TLR7 interfered with macrophage proinflammatory responses to TLR2 and TLR4 ligands, reduced monocyte chemoattractant protein-1 production, and prevented expansion of Ly6Chi inflammatory monocytes and accumulation of inflammatory M1 macrophages into developing atherosclerotic lesions. In human carotid endarterectomy specimens TLR7 levels were consistently associated with an M2 anti-inflammatory macrophage signature (interleukin [IL]-10, IL-1RA, CD163, scavenger and C-type lectin receptors) and collagen genes, whereas they were inversely related or unrelated to proinflammatory mediators (IL-12/IL-23, interferon beta, interferon gamma, CD40L) and platelet markers. Moreover, in human atheroma cultures, TLR7 activation selectively suppressed the production of key proatherogenic factors such as monocyte chemoattractant protein-1 and tumor necrosis factor without affecting IL-10. Conclusions These findings provide evidence for a beneficial role of TLR7 in atherosclerosis by constraining inflammatory macrophage activation and cytokine production. This challenges the prevailing concept that all TLRs are pathogenic and supports the exploitation of the TLR7 pathway for therapy.
Chrysanthi L. Skevaki, Ioanna E. Galani, Michail V. Pararas, Konstantina P. Giannopoulou, and Athanassios Tsakris
Springer Science and Business Media LLC
Viral conjunctivitis is one of the most common disorders observed in ophthalmic emergency departments, yet no established treatment exists. Lately, antiviral medications have been introduced into clinical practice; however, a systematic review focusing on their use and effectiveness in the treatment of viral conjunctivitis has not been previously reported. We systemically reviewed the literature to identify studies where antiviral drugs were used to treat viral conjunctivitis. Currently, aciclovir, trifluridine and valaciclovir are commonly used as antiviral agents to treat herpesvirus infections. Cidofovir has been used successfully to treat some cases of adenoviral conjunctivitis, although toxicity has also been reported. The use of other medications, such as idoxuridine, has been minimized in clinical practice due to their high toxicity. Interestingly, most of the antiviral drugs developed are used to treat herpesvirus infections, while less progress has been made in the field of adenoviral infections. For other viral causes of conjunctivitis, no effective remedy is currently available, and treatment focuses on the relief of symptoms. Caution should be exercised when coadministering other pharmacological agents, such as corticosteroids, because of emerging adverse effects.
Jing Ni, Ioanna E. Galani, Adelheid Cerwenka, Volker Schirrmacher, and Philippe Fournier
Elsevier BV
A plasmid encoding the Hemagglutinin-Neuraminidase (HN) protein of Newcastle Disease Virus (pHN) was tested for its capacity to stimulate innate anti-tumor activity in tumor-bearing mice. We observed that application of the pHN plasmid at the ear pinna site (i.e.) of mice induces higher levels of systemic interferon-α and reduced tumor growth in the prophylactic mammary carcinoma DA3 tumor model in comparison to application of a control plasmid not encoding the HN protein. Analysis of the tumor microenvironment revealed a significant increase in NK cell infiltration and decrease in infiltration of CD11b(+)Gr-1(high) myeloid cells bearing the myeloid-derived suppressor cell (MDSC) phenotype after vaccination with the pHN DNA compared to a control DNA. Finally, innate immunity and partially type I IFN responses were proved important for the reduction of s.c. RMA-S tumor growth after pHN vaccination, as shown with the use of RAG2(-/-) and RAG2(-/-)IFNAR1(-/-) mice. These data demonstrate that triggering innate immunity by pHN application at the ear pinna of mice modulates the immune cell compartment in the tumor microenvironment and reduces tumor growth. This highlights thus the potential adjuvant activity of the HN gene in tumor therapy.
Ioanna E. Galani, Marco Wendel, Ana Stojanovic, Maria Jesiak, Margareta M. Müller, Carola Schellack, Elisabeth Suri-Payer, and Adelheid Cerwenka
Wiley
Strategies of manipulating immunosuppressive regulatory T cells (Treg) in cancer patients are currently evaluated in clinical trials. Treg suppress immune responses of tumor‐specific T cells; yet, relatively little is known about the impact of Treg on innate immune cells in tumor models in vivo. Many tumors lose expression of MHC class I. Therefore, our study aimed at defining strategies to strengthen immune responses against a high tumor burden of the MHC class I‐deficient mouse lymphoma RMA‐S. We demonstrate that Treg depletion in mice led to tumor rejection that was dependent on T cells, NK cells and IFN‐γ. In the absence of Treg elevated levels of IFN‐γ were produced by tumor‐infiltrating T cells and NK cells. Tumor rejection observed in the absence of Treg correlated with a substantial IFN‐γ‐dependent increase in the numbers of tumor‐infiltrating leukocytes. The most abundant cell population in the tumors was macrophages. Tumor‐infiltrating macrophages from Treg‐depleted mice expressed increased amounts of MHC class II, produced highly enhanced levels of pro‐inflammatory cytokines and inhibited tumor cell proliferation. It was reported that tumor‐infiltrating macrophages have multi‐faceted functions promoting or counteracting tumor growth. In our study, high numbers of macrophages infiltrating RMA‐S tumors in the absence of Treg correlated with tumor rejection suggesting that macrophages are additional targets for Treg‐mediated immune suppression in cancer.
Michael K. Kiessling, Claus D. Klemke, Marcin M. Kamiński, Ioanna E. Galani, Peter H. Krammer, and Karsten Gülow
American Association for Cancer Research (AACR)
Aberrant signaling of the nuclear facotr (NF-kappaB) pathway has been identified as a mediator of survival and apoptosis resistance in leukemias and lymphomas. Here, we report that cell death of cutaneous T-cell lymphoma cell lines induced by inhibition of the NF-kappaB pathway is independent of caspases or classic death receptors. We found that free intracellular iron and reactive oxygen species (ROS) are the main mediators of this cell death. Antioxidants such as N-Acetyl-l-cysteine and glutathione or the iron chelator desferrioxamine effectively block cell death in cutaneous T-cell lymphoma cell lines or primary T cells from Sézary patients. We show that inhibition of constitutively active NF-kappaB causes down-regulation of ferritin heavy chain (FHC) that leads to an increase of free intracellular iron, which, in turn, induces massive generation of ROS. Furthermore, direct down-regulation of FHC by siRNA caused a ROS-dependent cell death. Finally, high concentrations of ROS induce cell death of malignant T cells. In contrast, T cells isolated from healthy donors do not display down-regulation of FHC and, therefore, do not show an increase in iron and cell death upon NF-kappaB inhibition. In addition, in a murine T-cell lymphoma model, we show that inhibition of NF-kappaB and subsequent down-regulation of FHC significantly delays tumor growth in vivo. Thus, our results promote FHC as a potential target for effective therapy in lymphomas with aberrant NF-kappaB signaling.
Norman Nausch, Ioanna E. Galani, Eva Schlecker, and Adelheid Cerwenka
American Society of Hematology
Abstract Myeloid-derived suppressor cells (MDSCs) accumulate in cancer patients and tumor-bearing mice and potently suppress T-cell activation. In this study, we investigated whether MDSCs regu-late natural killer (NK)–cell function. We discovered that mononuclear Gr-1+CD11b+F4/80+ MDSCs isolated from RMA-S tumor-bearing mice do not suppress, but activate NK cells to produce high amounts of IFN-γ. Gr-1+CD11b+F4/80+ MDSCs isolated from tumor-bearing mice, but not myeloid cells from naive mice, expressed the ligand for the activating receptor NKG2D, RAE-1. NK-cell activation by MDSCs depended partially on the interaction of NKG2D on NK cells with RAE-1 on MDSCs. NK cells eliminated Gr-1+CD11b+F4/80+ MDSCs in vitro and upon adoptive transfer in vivo. Finally, depletion of Gr-1+ cells that comprise MDSCs confirmed their protective role against the NK-sensitive RMA-S lymphoma in vivo. Our study reveals that MDSCs do not suppress all aspects of antitumor immune responses and defines a novel, unexpected activating role of MDSCs on NK cells. Thus, our results have great impact on the design of immune therapies against cancer aiming at the manipulation of MDSCs.