Chromatin accessibility landscapes of WT and Batf-/- ILC2s sorted from lungs at day 9 after influenza virus infection
Ontology highlight
ABSTRACT: Activated type 2 innate lymphoid cells (ILC2s) accumulate and promote inflammatory resolution and tissue repair in host defense against acute respiratory viral infections. However, whether an ILC2 subset that specializes in wound healing exists, and the mechanisms by which ILC2 cells contribute to tissue repair remain elusive. Using single-cell RNA-sequencing (scRNA-seq), we identified a transcriptionally distinct ILC2 subset that showed enrichment for wound healing signature genes and the transcription factor BATF. Notably, BATF promoted the proliferation and function of ILC2s and restricted their plasticity during infection with influenza virus. In the absence of BATF, ILC2s lost their immune protective properties and obtained pathogenic ILC3-like function, which led to persist neutrophil infiltration, tissue damage and lethality. Mechanistically, BATF directly bound the cis-regulatory elements of wound healing genes, maintained their chromatin accessibility and promoted their expression. Lastly, BATF played an important role in an IL-33-ST2 feed-forward loop that supports ILC2 cell identity and function. Collectively, our findings shed light on a BATF-dependent ILC2 program thereby providing a potential therapeutic target for terminating detrimental inflammation during acute viral infection.
Project description:Activated type 2 innate lymphoid cells (ILC2s) accumulate and promote inflammatory resolution and tissue repair in host defense against acute respiratory viral infections. However, whether an ILC2 subset that specializes in wound healing exists, and the mechanisms by which ILC2 cells contribute to tissue repair remain elusive. Using single-cell RNA-sequencing (scRNA-seq), we identified a transcriptionally distinct ILC2 subset that showed enrichment for wound healing signature genes and the transcription factor BATF. Notably, BATF promoted the proliferation and function of ILC2s and restricted their plasticity during infection with influenza virus. In the absence of BATF, ILC2s lost their immune protective properties and obtained pathogenic ILC3-like function, which led to persist neutrophil infiltration, tissue damage and lethality. Mechanistically, BATF directly bound the cis-regulatory elements of wound healing genes, maintained their chromatin accessibility and promoted their expression. Lastly, BATF played an important role in an IL-33-ST2 feed-forward loop that supports ILC2 cell identity and function. Collectively, our findings shed light on a BATF-dependent ILC2 program thereby providing a potential therapeutic target for terminating detrimental inflammation during acute viral infection.
Project description:Activated type 2 innate lymphoid cells (ILC2s) accumulate and promote inflammatory resolution and tissue repair in host defense against acute respiratory viral infections. However, whether an ILC2 subset that specializes in wound healing exists, and the mechanisms by which ILC2 cells contribute to tissue repair remain elusive. Using single-cell RNA-sequencing (scRNA-seq), we identified a transcriptionally distinct ILC2 subset that showed enrichment for wound healing signature genes and the transcription factor BATF. Notably, BATF promoted the proliferation and function of ILC2s and restricted their plasticity during infection with influenza virus. In the absence of BATF, ILC2s lost their immune protective properties and obtained pathogenic ILC3-like function, which led to persist neutrophil infiltration, tissue damage and lethality. Mechanistically, BATF directly bound the cis-regulatory elements of wound healing genes, maintained their chromatin accessibility and promoted their expression. Lastly, BATF played an important role in an IL-33-ST2 feed-forward loop that supports ILC2 cell identity and function. Collectively, our findings shed light on a BATF-dependent ILC2 program thereby providing a potential therapeutic target for terminating detrimental inflammation during acute viral infection.
Project description:Activated type 2 innate lymphoid cells (ILC2s) accumulate and promote inflammatory resolution and tissue repair in host defense against acute respiratory viral infections. However, whether an ILC2 subset that specializes in wound healing exists, and the mechanisms by which ILC2 cells contribute to tissue repair remain elusive. Using single-cell RNA-sequencing (scRNA-seq), we identified a transcriptionally distinct ILC2 subset that showed enrichment for wound healing signature genes and the transcription factor BATF. Notably, BATF promoted the proliferation and function of ILC2s and restricted their plasticity during infection with influenza virus. In the absence of BATF, ILC2s lost their immune protective properties and obtained pathogenic ILC3-like function, which led to persist neutrophil infiltration, tissue damage and lethality. Mechanistically, BATF directly bound the cis-regulatory elements of wound healing genes, maintained their chromatin accessibility and promoted their expression. Lastly, BATF played an important role in an IL-33-ST2 feed-forward loop that supports ILC2 cell identity and function. Collectively, our findings shed light on a BATF-dependent ILC2 program thereby providing a potential therapeutic target for terminating detrimental inflammation during acute viral infection.
Project description:Activated type 2 innate lymphoid cells (ILC2s) accumulate and promote inflammatory resolution and tissue repair in host defense against acute respiratory viral infections. However, the heterogeneity of ILC2s in the lung and the mechanisms by which ILC2 cells contribute to tissue repair remain elusive. Using single-cell RNA-sequencing (scRNA-seq), we identified a transcriptionally distinct ILC2 subset that showed enrichment for wound healing signature genes and the transcription factor BATF. Notably, BATF promoted the proliferation and function of ILC2s and restricted their plasticity during infection with influenza virus. In the absence of BATF, ILC2s lost their immune protective properties and obtained pathogenic ILC3-like function, which led to persist neutrophil infiltration, tissue damage and lethality. Mechanistically, BATF directly bound the cis-regulatory elements of wound healing genes, maintained their chromatin accessibility and promoted their expression. Lastly, BATF played an important role in an IL-33-ST2 feed-forward loop that supports ILC2 cell identity and function. Collectively, our findings shed light on a BATF-dependent ILC2 program, thereby providing a potential therapeutic target for terminating detrimental inflammation during acute viral infection.
Project description:Studies over the past decade characterized murine regulatory T cells (Tregs) with the capacity to promote tissue regeneration. In humans, such a population of tissue-repair Treg cells has not been discovered yet. Using single-cell chromatin accessibility profiles of murine and human tissue Treg cells, we defined a species-conserved and microbiota-independent repair Treg signature, with a prevailing footprint of the transcription factor BATF. Combining this signature with gene expression profiling and TCR fate mapping, we identified a population of tissue-like Treg cells in peripheral blood, characterized by the expression of BATF, CCR8 and HLA-DR. Human BATF+CCR8+ Treg cells from normal skin and adipose tissue shared features with tumor-resident Treg and tissue T-follicular helper (Tfh) cells. Inducing a Tfh-like differentiation program in naive Treg cells partially recapitulated human tissue Treg characteristics, including enhanced wound healing potential
Project description:ILC2 cells are a newly described cell type whose biology and contribution to disease are poorly understood. ILC2 cells are activated by allergens, viral infection, and/or epithelial damage via IL-33 and IL-25. ILC2 cells require IL-2, IL-7, IL-25 and IL-33 for their survival and expansion. In mice, ILC2s produce multiple mediators primarily associated with type 2 inflammation (IL-13, IL-5, IL-4, IL-6, IL-9, IL-10, GM-CSF, amphiregulin). ILC2 cells may contribute to the pathology of asthma through multiple mediators that include IL-13-independent pathways. Our goal is to compare transcriptional profiles of IL-33- or IL-25-activated ILC2 cells from blood to characterize these cells and to identify marker(s) that can be utilized to detect them in human tissue. ILC2 cells (Lineage negative, CRTH2+, CD161+, CD127+) were purified from human blood of 5 different donors by flow cytometry. The ILC2 yield ranged from 20,000 to 165,000 cells per donor (0.001-0.008% WBC). Purified ILC2s were expanded in vitro in the presence of IL-2, IL-7, IL-33 and IL-25 (each at 50 ng/ml) for 7-10 days. Expanded cells maintained the ILC2 phenotype (Lineage negative, CRTH2+, CD161+, CD127+). The cells were rested for 2 days in the presence of 1 ng/ml IL-2 and IL-7 and then treated in the presence of 1 ng/ml IL-2 and IL-7 with either media control, IL-25 (50 ng/ml), IL-33 (50 ng/ml), and/or TSLP (50 ng/ml) in combination, for 6 or 24 hours. Whole RNA was isolated via the RNeasy kit (Qiagen). Stratagene Universal Human Reference RNA was used as the reference.
Project description:Type-2 innate lymphoid cells (ILC2s) promote anti-helminth responses and contribute to allergies. Though Bcl11b has been previously considered a T-lineage identity transcription factor (TF) that restrains the innate-cell genetic programs, we report here that Bcl11b is highly expressed in mature ILC2s and acts upstream of the key ILC2 TFs Gfi1, Gata-3, and of IL-33 receptor IL1rl1 (T1ST2). Additionally, Bcl11b-/- ILC2s de-repressed Rorγt, Ahr and IL-23 receptor, normally expressed in type-3 ILCs (ILC3s). Consequently, Bcl11b-/- ILC2s lost ILC2 functions and gained ILC3 functions, expanding in response to the protease allergen papain, however producing IL-17 and IL-22, and not IL-5 and IL-13, causing lung neutrophilia rather than eosinophilia, and diminished mucus production. Our results broaden Bcl11b's role from a T-cell only TF, and establishes that Bcl11b sustains mature ILC2 genetic and functional programs and lineage fidelity through positive regulation of essential ILC2 TFs and negative regulation of pivotal ILC3 TFs. RNA-seq analysis on sorted ILC2s from the mLNs of Bcl11bF/F Cre-ERT2 and wildtype mice at steady state following tamoxifen mediated deletion of Bcl11b
Project description:Group 2 innate lymphoid cells (ILC2s) orchestrate protective type 2 immunity and tissue homeostatis, but have also been implicated in major human type 2 immunopathologies. However, our understanding of the mechanisms that control human ILC2 activity and phenotypic heterogeneity under inflammatory conditions remains limited. We integrated transcriptome profiling, flowcytometry characterization and functional assays to characterize human ILC2s from non-inflamed and inflamed microenvironments. We show that the transition from a resting to an activated inflammatory state in ILC2s is accompanied by a CD45RA-to-CD45RO isoform switch. CD45RA phosphatase activity suppresses ILC2 activation in resting cells, while exposure to activating cytokines induces IRF4/BATF transcription factors to promote a switch to the enzymatically restrained CD45RO isoform. Importantly, CD45RO+ ILC2 levels are increased in nasal polyps but also in the circulation of patients with chronic rhinosinusitis and asthma, which correlates with disease severity and resistance to steroid therapy. CD45RA-to-CD45RO conversion in ILC2s is sensitive to suppression by glucocorticosteroids, a mainstay therapy for patients with type-2 inflammatory disease. However, once converted, CD45RO+ ILC2s are resistant to steroids, likely via unique intrinsic metabolic reprogramming. In summary, we identify an inflammatory ILC2 subset in humans that is marked by CD45RO and is linked to severe type-2 inflammatory disease and steroid resistance.
Project description:Wound healing is impaired by infection; however, how microbe-induced inflammation modulates tissue repair remains unclear. We took advantage of the optical transparency of zebrafish and a genetically tractable microbe, Listeria monocytogenes, to probe the role of infection and inflammation in wound healing. We found a critical window of microbial clearance necessary to limit persistent inflammation and enable efficient wound repair. Infection with bacteria engineered to activate the inflammasome, Lm-Pyro, induced persistent inflammation and impaired healing despite low bacterial burden. In contrast, infection with an anti-inflammatory, apoptosis inducing strain, Lm-Apo, had similar infectious burden but was associated with rapid wound repair. Inflammatory infections induced il-1b expression and blocking IL-1R signaling partially rescued wound healing in the presence of persistent infection. Taken together, our findings suggest that the dynamics of microbe-induced tissue inflammation impacts repair in complex tissue damage independent of bacterial load, with a critical early window for efficient tissue repair.
Project description:Tissue repair processes maintain proper organ function following mechanical or infection related damage. In addition to anti-bacterial properties, MAIT cells express a tissue repair transcriptomic program and promote skin wound healing when expanded. Herein, we use a human‑like full‑thickness skin excision mouse model to assess the underlying mechanisms of MAIT cell tissue repair function. Single-cell RNAseq analysis suggests that skin MAIT cells already express a repair program at steady state. Following skin excision, MAIT cells promote keratinocyte proliferation thereby accelerating healing. Using skin grafts, parabiosis and adoptive transfer experiments, we show that MAIT cells migrate into the wound from other tissues in a TCR independent but CXCR6 dependent manner. Amphiregulin secreted by MAIT cells following excision promotes wound healing. The repair function is independent of sustained TCR stimulation. Overall, our study provides mechanistic insight into MAIT cell wound healing function in the skin.