Group 2 Innate Lymphoid Cells (ILC2) Suppress Beneficial Type 1 Immune Responses During Pulmonary Cryptococcosis

Cryptococcus neoformans is an opportunistic fungal pathogen preferentially causing disease in immunocompromised individuals such as organ-transplant-recipients, patients receiving immunosuppressive medications or, in particular, individuals suffering from HIV infection. Numerous studies clearly indicated that the control of C. neoformans infections is strongly dependent on a prototypic type 1 immune response and classical macrophage activation, whereas type 2-biased immunity and alternative activation of macrophages has been rather implicated in disease progression and detrimental outcomes. However, little is known about regulatory pathways modulating and balancing immune responses during early phases of pulmonary cryptococcosis. Here, we analyzed the role of group 2 innate lymphoid cells (ILC2s) for the control of C. neoformans infection. Using an intranasal infection model with a highly virulent C. neoformans strain, we found that ILC2 numbers were strongly increased in C. neoformans-infected lungs along with induction of a type 2 response. Mice lacking ILC2s due to conditional deficiency of the transcription factor RAR-related orphan receptor alpha (Rora) displayed a massive downregulation of features of type 2 immunity as reflected by reduced levels of the type 2 signature cytokines IL-4, IL-5, and IL-13 at 14 days post-infection. Moreover, ILC2 deficiency was accompanied with increased type 1 immunity and classical macrophage activation, while the pulmonary numbers of eosinophils and alternatively activated macrophages were reduced in these mice. Importantly, this shift in pulmonary macrophage polarization in ILC2-deficient mice correlated with improved fungal control and prolonged survival of infected mice. Conversely, adoptive transfer of ILC2s was associated with a type 2 bias associated with less efficient anti-fungal immunity in lungs of recipient mice. Collectively, our date indicate a non-redundant role of ILC2 in orchestrating myeloid anti-cryptococcal immune responses toward a disease exacerbating phenotype

Die Rolle der C-C Typ Chemokinrezeptoren CCR4 und CCR8 in Migration und Effektorfunktion von innate lymphoid cells type 2 (ILC2s)

Intense research over the past few years identified innate lymphoid cells type 2 (ILC2s) as one of the most important immune cell populations to mediate type 2-associated inflammation, such as protective immunity in parasitic worm infections and pathogenic responses in airway disorders. Their immunoregulatory capacity is well characterized and largely mediated by the production of type 2 signature cytokines at mucosal barrier surfaces. However, the molecular and immunological processes involved in the migration and regulation of ILC2s are poorly understood. In this context, chemokine receptor signaling is proposed to orchestrate organ-specific homing and inter-organ trafficking of ILC2s. Since initial data revealed specific and strong expression of CCR4 and CCR8 on ILC2s within ILC subsets, the objective of this thesis was to elucidate the ILC2-intrinsic role of these chemokine receptors. In accordance with a presumed chemotactic function, CCR4 ligands attracted ILC2s in vitro and in vivo. CCR4 signaling further mediated pulmonary ILC2 recruitment and induction of inflammation in a model of house dust mite (HDM)-provoked asthma. Conversely, in vitro and in vivo experiments showed no role of CCR8 signaling in the migration of ILC2s. We instead revealed that ILC2s produce the CCR8 ligand CCL1 in cell cultures and are a major source of CCL1 in vivo. In vitro, autocrine CCL1 signaling promoted survival, growth and effector cytokine production, especially of the survival cytokine IL-9. Experiments where mice were infected with the helminth N. brasiliensis showed that ILC2-intrinsic CCR8 signaling has a critical role in pulmonary ILC2 accumulation, induction of type 2 immune responses and efficient parasite defense. For these reasons, we propose an autocrine CCL1/CCR8-mediated mechanism that potentiates lung-resident ILC2 responses, potentially by the regulation of IL-9 production, to support their capacity to combat helminths. Collectively, we newly described two critical chemokine receptor signaling pathways that regulate ILC2 function in type 2 related inflammatory processes. Although CCR4 and CCR8 are described as related molecules in terms of their expression patterns and previously known functions in immune responses, these chemokine receptors execute divergent roles in ILC2s. This work contributes to our understanding of chemokine biology and could support the development of novel clinical approaches, involving CCR4 and CCR8 as promising targets for innovative immunotherapies.Intensive Forschung in den letzten Jahren identifizierte angeborene lymphoide Zellen Typ 2 (engl.: Innate lymphoid cells type 2; ILC2s) als eine der wichtigsten Immunzellpopulationen zur Vermittlung von Typ 2-assoziierten Entzündungen, wie beispielsweise schützende Immunität bei parasitären Wurminfektionen und pathogene Antworten bei Atemwegserkrankungen. Ihre immunregulatorische Kapazität ist gut charakterisiert und wird weitgehend durch die Produktion von charakteristischen Typ 2 Zytokinen an mukosalen Oberflächen vermittelt. Allerdings sind die molekularen und immunologischen Prozesse bei der Migration und Regulation von ILC2s unzureichend verstanden. In diesem Zusammenhang wird vermutet, dass Chemokinrezeptoren die organspezifische Auswanderung von ILC2s sowie deren Migration zwischen den Organen vermitteln. Da erste Daten eine spezifische und starke Expression von CCR4 und CCR8 auf ILC2s innerhalb der ILC Gruppe aufzeigten, war das Ziel dieser Arbeit die ILC2 spezifische Rolle dieser Chemokinrezeptoren zu untersuchen. Entsprechend der vermuteten chemotaktischen Funktion lockten CCR4 Liganden ILC2s in vitro und in vivo an. Zusätzlich vermittelte die CCR4 Signaltransduktion eine pulmonale ILC2 Rekrutierung und induzierte eine Entzündung in einem Hausstaubmilben (engl.: House dust mite; HDM)-ausgelösten Asthmamodell. Im Gegensatz dazu zeigten in vitro und in vivo Experimente keine Rolle von CCR8 in der Migration von ILC2s. Stattdessen entdeckten wir, dass kultivierte ILC2s den CCR8 Liganden CCL1 produzieren und eine Hauptquelle für CCL1 in vivo sind. In vitro förderte autokrines CCL1 das Überleben, Wachstum und Effektorzytokinproduktion, besonders des Überlebenszytokins IL 9. Infektionsversuche mit dem Helminth N. brasiliensis zeigten, dass die CCR8 Signaltransduktion in ILC2s unerlässlich für eine pulmonale ILC2 Akkumulierung, Induktion von Typ 2 Immunantworten und effiziente Parasitenabwehr ist. Aufgrund dessen vermuten wir einen autokrinen CCL1/CCR8 vermittelten Mechanismus, welcher Lungen-ansässige ILC2 Antworten potenziert um ihre Fähigkeit zur effizienten Abwehr von Helminthen, möglicherweise durch die Regulation von IL-9, zu unterstützen. Zusammenfassend haben wir zwei entscheidende Chemokinrezeptor-Signalwege neu beschrieben, welche die Funktion von ILC2s in Typ 2 Entzündungsprozessen regulieren. Obwohl CCR4 und CCR8 als verwandte Moleküle bezüglich ihrer Expressionmuster und zuvor bekannter Funktion in Immunantworten gelten, besitzen diese Chemokinrezeptoren uneinheitliche Rollen in ILC2s. Diese Arbeit trägt zu unserem Verständnis der Chemokinbiologie bei und kann die Entwicklung von neuen klinischen Anwendungen unterstützen, da CCR4 und CCR8 vielversprechende Zielmoleküle für innovative Immuntherapien sind

Group 2 Innate Lymphoid Cells (ILC2) Suppress Beneficial Type 1 Immune Responses During Pulmonary Cryptococcosis

Cryptococcus neoformans is an opportunistic fungal pathogen preferentially causing disease in immunocompromised individuals such as organ-transplant-recipients, patients receiving immunosuppressive medications or, in particular, individuals suffering from HIV infection. Numerous studies clearly indicated that the control of C. neoformans infections is strongly dependent on a prototypic type 1 immune response and classical macrophage activation, whereas type 2-biased immunity and alternative activation of macrophages has been rather implicated in disease progression and detrimental outcomes. However, little is known about regulatory pathways modulating and balancing immune responses during early phases of pulmonary cryptococcosis. Here, we analyzed the role of group 2 innate lymphoid cells (ILC2s) for the control of C. neoformans infection. Using an intranasal infection model with a highly virulent C. neoformans strain, we found that ILC2 numbers were strongly increased in C. neoformans-infected lungs along with induction of a type 2 response. Mice lacking ILC2s due to conditional deficiency of the transcription factor RAR-related orphan receptor alpha (Rora) displayed a massive downregulation of features of type 2 immunity as reflected by reduced levels of the type 2 signature cytokines IL-4, IL-5, and IL-13 at 14 days post-infection. Moreover, ILC2 deficiency was accompanied with increased type 1 immunity and classical macrophage activation, while the pulmonary numbers of eosinophils and alternatively activated macrophages were reduced in these mice. Importantly, this shift in pulmonary macrophage polarization in ILC2-deficient mice correlated with improved fungal control and prolonged survival of infected mice. Conversely, adoptive transfer of ILC2s was associated with a type 2 bias associated with less efficient anti-fungal immunity in lungs of recipient mice. Collectively, our date indicate a non-redundant role of ILC2 in orchestrating myeloid anti-cryptococcal immune responses toward a disease exacerbating phenotype

Group 2 Innate Lymphoid Cells (ILC2) Suppress Beneficial Type 1 Immune Responses During Pulmonary Cryptococcosis

Cryptococcus neoformans is an opportunistic fungal pathogen preferentially causing disease in immunocompromised individuals such as organ-transplant-recipients, patients receiving immunosuppressive medications or, in particular, individuals suffering from HIV infection. Numerous studies clearly indicated that the control of C. neoformans infections is strongly dependent on a prototypic type 1 immune response and classical macrophage activation, whereas type 2-biased immunity and alternative activation of macrophages has been rather implicated in disease progression and detrimental outcomes. However, little is known about regulatory pathways modulating and balancing immune responses during early phases of pulmonary cryptococcosis. Here, we analyzed the role of group 2 innate lymphoid cells (ILC2s) for the control of C. neoformans infection. Using an intranasal infection model with a highly virulent C. neoformans strain, we found that ILC2 numbers were strongly increased in C. neoformans-infected lungs along with induction of a type 2 response. Mice lacking ILC2s due to conditional deficiency of the transcription factor RAR-related orphan receptor alpha (Rora) displayed a massive downregulation of features of type 2 immunity as reflected by reduced levels of the type 2 signature cytokines IL-4, IL-5, and IL-13 at 14 days post-infection. Moreover, ILC2 deficiency was accompanied with increased type 1 immunity and classical macrophage activation, while the pulmonary numbers of eosinophils and alternatively activated macrophages were reduced in these mice. Importantly, this shift in pulmonary macrophage polarization in ILC2-deficient mice correlated with improved fungal control and prolonged survival of infected mice. Conversely, adoptive transfer of ILC2s was associated with a type 2 bias associated with less efficient anti-fungal immunity in lungs of recipient mice. Collectively, our date indicate a non-redundant role of ILC2 in orchestrating myeloid anti-cryptococcal immune responses toward a disease exacerbating phenotype

Targeted deletion of NFAT-Interacting-Protein-(NIP) 45 resolves experimental asthma by inhibiting Innate Lymphoid Cells group 2 (ILC2)

Here we investigated the role of NFAT-interacting protein (NIP)-45, an Interleukin (IL)-4 inducing Transcription Factor, and its impact on the differentiation of Group 2 Innate -Lymphoid -Cells (ILC2s) in the pathogenesis of asthma. NIP45, a transcription factor regulating NFATc1 activity, mRNA was found to be induced in the Peripheral Blood mononuclear cells (PMBCs) of asthmatic pre-school children with allergies and in the peripheral blood CD4+ T cells from adult asthmatic patients. In PBMCs of asthmatic and control children, NIP45 mRNA directly correlated with NFATc1 but not with T-bet. Targeted deletion of NIP45 in mice resulted in a protective phenotype in experimental asthma with reduced airway mucus production, airway hyperresponsiveness and eosinophils. This phenotype was reversed by intranasal delivery of recombinant r-IL-33. Consistently, ILC2s and not GATA3+ CD4+ T-cells were decreased in the lungs of asthmatic NIP45−/− mice. Reduced cell number spleen ILC2s could be differentiated from NIP45−/− as compared to wild-type mice after in vivo injection of a microcircle-DNA vector expressing IL-25 and decreased cytokines and ILC2 markers in ILC2 differentiated from the bone marrow of NIP45−/− mice. NIP45 thus emerges as a new therapeutic target for the resolution of the airway pathology, down-regulation of ILC2s and mucus production in asthma

Ethanol consumption inhibits TFH cell responses and the development of autoimmune arthritis

Alcohol consumption is a consistent protective factor for the development of autoimmune diseases such as rheumatoid arthritis (RA). The underlying mechanism for this tolerance-inducing effect of alcohol, however, is unknown. Here we show that alcohol and its metabolite acetate alter the functional state of T follicular helper (T-FH) cells in vitro and in vivo, thereby exerting immune regulatory and tolerance-inducing properties. Alcohol-exposed mice have reduced Bcl6 and PD-1 expression as well as IL-21 production by T-FH cells, preventing proper spatial organization of T-FH cells to form T-FH:B cell conjugates in germinal centers. This effect is associated with impaired autoantibody formation, and mitigates experimental autoimmune arthritis. By contrast, T cell independent immune responses and passive models of arthritis are not affected by alcohol exposure. These data clarify the immune regulatory and tolerance-inducing effect of alcohol consumption. Moderate consumption of alcohol is associated with protection from some autoimmune diseases. Here the authors show that ethanol and its metabolite acetate can protect mice from collagen-induced arthritis and provide evidence that the mechanism of this effect might be via inhibition of the effector function of T follicular helper cells