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Voehringer, D.

Publications and source records attributed to Voehringer, D..

15 recordsLinked to original sources

Persistent activation of STAT6 in keratinocytes elicits neutrophilic skin inflammation, pruritus and S. aureus colonization reminiscent of chronic atopic dermatitis

Atopic dermatitis (AD) evolves from initial type 2 immunity-driven inflammation to chronic mixed responses by poorly understood mechanisms. To investigate how the prolonged activation of the usually IL-4/IL-13-induced transcription factor STAT6 in keratinocytes impacts on the development and subtype of AD, we generated a new mouse model in which a constitutively active form of STAT6 is selectively expressed in keratinocytes. These K14Cre+STAT6vt/vt mice spontaneously developed AD-like skin lesions characterized by Staphylococcus aureus colonization, neutrophilic inflammation, and pruritus starting at the age of 12-14 weeks. Treatment with antibiotics mitigated pathology, indicating that it is microbiota-driven. Comparison of human AD gene expression data with the transcriptome of skin biopsies from K14Cre+STAT6vt/vt mice revealed features shared with chronic AD, including genes associated with neutrophil and keratinocyte activation. Furthermore, heterozygous K14Cre+STAT6vt/wt mice developed a mixed eosinophilic and neutrophilic skin inflammation with exacerbated pathology compared to wild-type controls in an induced model of atopic dermatitis, compatible with chronic AD. These results indicate that persistent STAT6 activity in keratinocytes facilitates S. aureus outgrowth on the skin, promotes a type 1-/type 3-biased immune response, and is sufficient to mimic the transition from acute type 2 immunity-to chronic type 1-/type 3-immunity-dominated AD.

immunology↗

ILC2s govern imprinting of alveolar macrophage-mediated immunity upon secondary helminth infection in the lung

Hookworm parasites migrate through the pulmonary system as part of their lifecycle, causing significant tissue damage that activates tissue-resident cell populations such as ILC2s. These cells drive type 2 immune responses critical for wound healing and the development of protective immunity. Macrophages, particularly monocyte-derived macrophages that seed the lung after infection, are central effectors of these responses and may be distinct from the tissue-resident populations they replace. However, the cellular and molecular factors governing the attrition of tissue-resident (TR) macrophages and their replacement remain poorly understood. We find that ILC2s and IL-4/IL-13-producing CD4+ T cells bi-directionally interact to regulate alveolar macrophage (AM) populations during infection. In the absence of these cells, type 2 immune responses are muted, leading to impaired anti-parasitic immunity in the lung during re-infection. This correlates with diminished expansion of type 2-polarized monocyte-derived alveolar macrophages (Mo-AMs), which are metabolically and transcriptionally distinct from TR-AMs. While Mo-AMs highly upregulated expression of Arg1, this was not essential for development of protective immunity in the lung. Concomitant with a more glycolytic metabolism, ILC2-induced Mo-AMs selectively upregulate arachidonate 15-lipoxygenase (Alox15), which promotes the capacity of macrophages to attack parasites in vitro. These results identify ILC2s as critical regulators of alveolar macrophage dynamics and important mediators of their function during helminth infection of the lung.

immunology↗

Il33 expressing cDC2s promote expansion of ILC2s and eosinophilia in fungal airway inflammation in male mice

Eosinophilic allergic asthma is often associated with fungal sensitization and represents the dominant form of asthma in adolescents. The mechanisms by which lung eosinophilia is regulated in this context are incompletely understood. Here, we demonstrate that type 2 innate lymphoid cells (ILC2s) are generally required in addition to Th2 cells for Aspergillus fumigatus-elicited eosinophilic lung inflammation in mice and this effect was independent of ILC2-derived IL-5. Surprisingly, expansion of ILC2s in male mice was ST2-independent, but required expression of Il33 in cDC2s induced by Th2-derived IL-4/13. This IL-33-plus IL-4-regulated transcriptional module in cDC2s included expression of factors associated with activation of ILC2s and was restricted to CCR7+ cDC2s in the inflamed lung. Our findings uncovered a novel intimate cross-talk between IL-33+ cDC2s, ILC2s and Th2 cells to orchestrate eosinophilia in a sex-dependent manner upon A. fumigatus-induced allergic lung inflammation.

immunology↗

IRF4 is a master regulator of multinucleated giant cell formation

Multinucleated giant cells (MGCs) are a hallmark pathological feature of a wide range of diseases, yet the mechanisms underlying their formation and function remain poorly understood. Although it is recognized that MGCs arise from a heterogeneous pool of myeloid precursors, how a committed MGC fate develops therein remains unknown. Here, combining temporal in vitro and in vivo differentiation of bone marrow-derived myeloid precursors with single cell and bulk RNA sequencing as well as CRISPR/Cas9-mediated gene editing, we shed insight into how MGCs emerge. Our findings reveal that coordinated upregulation of cell fusion genes and cellular metabolism, particularly oxidative phosphorylation, regulate the transition from macrophage progenitors to fusion competent cells. In vivo fate-mapping unveils Ms4a3-, and Cd11c-but not Cx3cr1-traced cells as the predominant precursor populations for MGCs in a lung granuloma formation model. Notably, transcription factor profiling in the progression from early myeloid precursors to pre-MGCs identifies IRF4 as a key molecular switch driving MGC generation. IRF4+ MGCs are present in different pathologies, including Schistosoma mansoni egg induced granulomas, Aspergillus fumigatus conidia mediated allergic airway inflammation and human head and neck squamous cell carcinomas. Mechanistically, IRF4 controls critical fusion related genes such as Dcstamp and Ocstamp. Consequently, Irf4 deficient cells are unable to develop into MGCs. Collectively, our work delineates the trajectory of MGC differentiation, establishing IRF4 as a defining transcription factor required for the generation of fusion-competent progenitors that ultimately give rise to MGCs.

immunology↗

The synovial lining macrophage layer develops in the first weeks of life in a CSF1- and TGFβ- dependent but monocyte-independent process.

Synovial joints harbor a protective lining layer, consisting of fibroblasts and macrophages, which form an epithelial-like barrier. In inflamed joints, lining macrophages regulate both early inflammatory cell influx and resolution. Despite these critical functions, it is currently unknown at what stage during development the synovial macrophage lining is established, and which signals drive this process. Here, we use a combination of genetic models and in vivo perturbations, single cell transcriptomics and imaging to delineate the process of lining formation in mice. We find that the synovial lining is immature at birth and becomes established within the first 3 weeks of life. In this window, the lining is gradually populated with macrophages that originate from fetal sources, proliferate and acquire the lining-specific transcriptional identity. In contrast, monocytes contribute only minimally to the developing lining, and their input remains limited in healthy adulthood. We identify CSF1 and TGF{beta} as key signals in this process, which also involves mechanosensing through PIEZO1. Our study thus identifies the early postnatal window as a critical period for lining macrophage development, with potential lifelong impact on joint health and disease.

immunology↗

The metabolic program of inflammatory eosinophils accounts for chronic parasite-induced skin-disease

Eosinophils exert antimicrobial, cytotoxic and immunoregulatory effects, but their function in cutaneous tissue still remains poorly understood. Here, we used a mouse model of chronic cutaneous leishmaniasis caused by the protozoan parasite Leishmania (L.) mexicana to investigate the function and transcriptomic signature of eosinophils in the skin. In C57BL/6 wild-type mice, L. mexicana infection induced local and systemic eosinophilia that was dependent on type 2 innate lymphoid cells and interleukin-5. Genetic and pharmacological depletion of eosinophils led to complete clinical resolution of disease, which was accompanied by a more pronounced Th1 and M1-like macrophage response. Bioinformatic analyses revealed a novel inflammatory and tissue-specific transcriptional trajectory in skin-infiltrating eosinophils. Skin-imprinted eosinophils strongly expressed the high-affinity glucose transporter 3 (Slc2a3), deprived the environment of glucose and directly impeded the function of Th1 cells. Together, our results demonstrate that disease progression and chronicity of L. mexicana infection is caused by inflammatory eosinophils and linked to their metabolic program. Short SummaryThe authors describe that depletion of eosinophils prevents chronic cutaneous disease caused by Leishmania mexicana. They identify a novel, tissue-specific transcriptomic profile of inflammatory skin eosinophils and demonstrate that skin-imprinted eosinophils show strong glucose uptake and directly repress Th1 responses. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/640104v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@3ecd3org.highwire.dtl.DTLVardef@1b1283forg.highwire.dtl.DTLVardef@1c941fdorg.highwire.dtl.DTLVardef@b7c39_HPS_FORMAT_FIGEXP M_FIG C_FIG KEY POINTSO_LIEosinophil accumulation precedes the development of chronic cutaneous leishmaniasis C_LIO_LIEosinophil depletion or IL-5 neutralization lead to clinical cure of the disease C_LIO_LIL. mexicana infection elicits a unique transcriptomic signature of skin eosinophils C_LIO_LISkin eosinophils show a marked uptake of glucose and directly repress Th1 responses C_LI

immunology↗

Comprehensive analysis of myeloid reporter mice

Macrophages are a pivotal cell type within the synovial lining and sub-lining of the joint, playing a crucial role in maintaining homeostasis of synovium. Although fate-mapping techniques have been employed to differentiate synovial macrophages from other synovial myeloid cells, no comprehensive study has yet been conducted within the mouse synovial macrophage compartment. In this study, we present, for the first time, lineage tracing results from 18 myeloid-specific fate-mapping models in mouse peripheral blood (PB) and synovial tissue. The identification of synovial macrophages and monocyte-lineage cells through flow cytometry was further validated using cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) datasets. These findings provide a valuable methodological tool for researchers to select appropriate models for studying the function of synovial myeloid cells and serve as a reference for investigations in other tissue types.

immunology↗

Lymphoid-tissue-on-chip recapitulates human antibody responses in vitro

In the past decades, vaccine development has made great strides. Nevertheless, more often than not, vaccine candidates fail in advanced stages of development and clinical trials. A key reason is the poor predictive value of non-clinical in vivo and in vitro models, due to either species-specific differences in the immune response or insufficient reflection of physiological vaccine mechanisms. Reliable modeling of human adaptive immune responses is a prerequisite to understand processes leading to vaccine-induced protective immunization and to drive informed decisions in vaccine development pipelines. Here, we present a centrifugal microfluidics based organ-on-chip approach to generate an organotypic high density lymphoid tissue on-chip. The model enables long-term culture of lymphoid tissue and raised antigen-specific antibody responses against influenza vaccines even after four weeks on-chip. Antibody response of different magnitude and quality could be induced both by direct antigen exposure as well as by recruitment of antigen-presenting cells from the periphery. The model represents an attractive approach to evaluate the impact of the mode of antigen delivery on adaptive immune responses. Beyond applications in vaccine development, the lymphoid-tissue-on-chip provides a platform to study cellular interactions during homeostasis, immune responses and long-term impact of immunomodulators over several weeks.

bioengineering↗

CD226+ adipose tissue macrophages arise from MDP-derived monocytes and regulate lipid metabolism.

Macrophages are innate immune cells present in all tissues, in which they participate in immune responses and maintenance of tissue homeostasis. They develop either from embryonic precursors or from circulating monocytes, and their origin impacts their functions. We previously observed robust recruitment of monocytes to brown adipose tissue in which they could differentiation into two distinct macrophage subsets identifiable by CD206 or CD226 expression. In the present study, we investigated monocyte differentiation pathways in brown adipose tissue and the function of monocyte-derived macrophages. Fate mapping analysis revealed a low contribution of GMP- and a high contribution of MDP-derived monocytes to the CD226high macrophage subset. Importantly, adoptive transfer experiments demonstrate that MDP- but not GMP-derived monocytes are pre-conditioned to give rise to CD226high macrophages. We found that MDP-derived CD226high macrophages were also present in other tissues including peritoneal cavity, adrenal glands and all adipose depots. CD226high macrophages were regulated by both GM-CSF and CSF1R. Genetic depletion of CD226high macrophages caused increased BAT and plasma triglyceride content. We thus identify CD226high MDP-derived macrophages as a new myeloid cell type conserved across tissues and tied to lipid metabolism homeostasis.

immunology↗

AZIN2-dependent polyamine metabolism determines adipocyte progenitor fate and protects against obesity and dysmetabolism

Adipose tissue homeostasis plays a critical role in metabolic disease but the metabolic circuitry regulating adipose tissue dynamics remains unclear. In this study, polyamine metabolism emerges as an important regulator of adipose tissue pathophysiology. We identify AZIN2 (Antizyme inhibitor 2), a protein promoting polyamine synthesis and acetylation, as a major regulator of total acetyl-CoA in adipocyte progenitors (APs). AZIN2 deficient APs demonstrate increased H3K27 acetylation marks in genes related to lipid metabolism, cell cycle arrest and cellular senescence, and enhanced adipogenesis compared to wild-type counterparts. Upon high-fat diet (HFD)-induced obesity, global AZIN2 deficiency in mice provokes adipose tissue hypertrophy, AP senescence, lipid storage perturbations, inflammation and insulin resistance. IL4 promotes Azin2 expression in APs but not mature adipocytes due to diminished IL4 receptor expression in the latter. In human visceral and subcutaneous adipose tissue, AZIN2 expression positively correlates with expression of early progenitor markers and genes associated with protection against insulin resistance, while it negatively correlates with markers of lipogenesis. In sum, AZIN2-driven polyamine metabolism preserves adipose tissue health, a finding that could be therapeutically harnessed for the management of obesity-associated metabolic disease.

cell biology↗

Selective ablation of thymic and peripheral Foxp3+ regulatory T cell development

Foxp3+ Treg cells of thymic (tTreg) and peripheral (pTreg) developmental origin are thought to synergistically act to ensure immune homeostasis, with self-reactive tTreg cells primarily constraining autoimmune responses. We exploited tTreg-specific GFP/Cre recombinase activity to selectively ablate either tTreg ({Delta}tTreg) or pTreg ({Delta}pTreg) cell development. In contrast to the tTreg cell behavior in {Delta}pTreg mice, pTreg cells with a highly activated suppressor phenotype replenished the Treg cell pool of C57BL/6.{Delta}tTreg mice, preventing early mortality and fatal autoimmunity. Even with advancing age, pTreg cells largely maintained immune tolerance in C57BL/6.{Delta}tTreg mice. However, only two generations of (C57BL/6>NOD) backcrossing precipitated severe disease lethality associated with a distinct, partially overlapping pattern of organ-specific autoimmunity. Genetic association studies defined a small set of autoimmune risk loci sufficient to unleash a particularly severe form of diabetes, including genes known to impinge on Treg cell biology. Thus, pTreg cells exhibit an unexpectedly high functional adaptability, emphasizing their importance as mediators of bystander effects to ensure self-tolerance. SUMMARYThis study in complementary loss-of-function mouse models uncovers an unexpected functional plasticity of pTreg cells in constraining systemic autoimmune responses in the absence of tTreg cells and identifies tTreg cells as primary regulators of {beta}-cell autoimmunity in type 1 diabetes.

immunology↗

Interleukin-13 and its receptor are synaptic proteins involved in plasticity and neuroprotection

Immune system molecules are expressed by neurons, often for unknown functions. We have identified IL-13 and its receptor IL-13Ra1 as neuronal, synaptic proteins in mouse, rat, and human brains, whose engagement upregulates the phosphorylation of NMDAR and AMPAR subunits and, in turn, increases synaptic activity and CREB-mediated transcription. We demonstrate that increased IL-13 is a hallmark of traumatic brain injury (TBI) in mice as well as in two distinct cohorts of human patients. We also provide evidence that IL-13 upregulation protects neurons from excitotoxic death. We show IL-13 upregulation occurring in several cohorts of human brain samples and in CSF. Thus, IL-13 is a previously unrecognized physiological modulator of synaptic physiology of neuronal origin, with implications for the establishment of synaptic plasticity and the survival of neurons under injury conditions. Furthermore, we suggest that the neuroprotection afforded through the upregulation of IL-13 represents a new entry point for interventions in the pathophysiology of TBI.

neuroscience↗

Th2 single-cell heterogeneity and clonal interorgan distribution in helminth-infected mice

Th2 cells provide effector functions in type 2 immune responses to helminths and allergens. Despite knowledge about molecular mechanisms of Th2 cell differentiation, there is little information on Th2 cell heterogeneity and clonal distribution between organs. To address this, we performed combined single-cell transcriptome and TCR clonotype analysis on murine Th2 cells in mesenteric lymph nodes (MLN) and lung after infection with Nippostrongylus brasiliensis (Nb) as a human hookworm infection model. We find organ-specific expression profiles, but also populations with conserved migration or effector/resident memory signatures that unexpectedly cluster with potentially regulatory Il10posFoxp3neg cells. A substantial MLN subpopulation with an interferon response signature suggests a role for interferon-signaling in Th2 differentiation or diversification. Further RNA-inferred developmental directions indicate proliferation as a hub for differentiation decisions. We also link long noted Cxcr3 expression in the Th2 compartment to a population of Il4pos NKT cells. Although the TCR repertoire is highly heterogeneous, we identified expanded clones and CDR3 motifs. Clonal relatedness between distant organs confirmed effective exchange of Th2 effector cells, although locally expanded clones dominated the response. These results provide new insights in Th2 cell subset diversity and clonal relatedness in distant organs.

immunology↗

IL-4 and helminth infection downregulate MINCLE-dependent macrophage response to mycobacteria and Th17 adjuvanticity

The myeloid C-type lectin receptor (CLR) MINCLE senses the mycobacterial cell wall component trehalose-6,6-dimycolate (TDM). Recently, we found that IL-4 down-regulates MINCLE expression in macrophages. IL-4 is a hallmark cytokine in helminth infections, which appear to increase the risk for mycobacterial infection and active tuberculosis. Here, we investigated functional consequences of IL-4 and helminth infection on MINCLE-driven macrophage activation and Th1/Th17 adjuvanticity. IL-4 inhibited MINCLE and cytokine induction after macrophage infection with Mycobacterium bovis Bacille Calmette-Guerin (BCG). Infection of mice with BCG upregulated MINCLE on myeloid cells, which was inhibited by IL-4 plasmid injection and by infection with the nematode Nippostrongylus brasiliensis in monocytes. To determine the impact of helminth infection on MINCLE-dependent immune responses, we vaccinated mice with a recombinant protein together with the MINCLE ligand Trehalose-6,6-dibehenate (TDB) as adjuvant. Concurrent infection with N. brasiliensis or with Schistosoma mansoni promoted T cell-derived IL-4 production and suppressed Th1/Th17 differentiation in the spleen. In contrast, helminth infection did not reduce Th1/Th17 induction by TDB in draining peripheral lymph nodes, where IL-4 levels were unaltered. Upon use of the TLR4-dependent adjuvant G3D6A, N. brasiliensis infection impaired selectively the induction of splenic antigen-specific Th1 but not of Th17 cells. Thus, helminth infection attenuated the Th17 response to MINCLE-dependent immunization in an organ-specific manner. Taken together, our results demonstrate down-regulation of MINCLE expression on monocytes and macrophages by IL-4 as a possible mechanism of thwarted Th17 vaccination responses by underlying helminth infection.

immunology↗

Natural IgE promotes epithelial hyperplasia and inflammation-driven tumour growth

IgE is the least abundant circulating antibody class but is constitutively present in healthy tissues bound to resident cells via its high-affinity receptor, Fc{varepsilon}RI. The physiological role of endogenous IgE is unclear but it is suggested to provide host protection against a variety of noxious environmental substances and parasitic infections at epithelial barrier surfaces. Here we show that skin inflammation enhances levels of IgE with natural specificities and with a similar repertoire, VDJ rearrangements and CDRH3 characteristics as in healthy tissue. IgE-bearing basophils are recruited to inflamed skin via CXCL12 and TSLP/IL-3-dependent upregulation of CXCR4. In the inflamed skin, IgE/Fc{varepsilon}RI-signalling in basophils promotes epithelial cell growth and differentiation, partly through histamine engagement of H1R and H4R. Furthermore, this natural IgE response strongly drives tumour outgrowth of epithelial cells harbouring oncogenic mutation. These findings indicate that natural IgE support skin barrier defences however during chronic tissue inflammation this may be subverted to promote tumour growth.

cancer biology↗