Periodic Reporting for period 4 - IMMCEPTION (Nociception and sensory nerves as regulators of type 2 immunity and skin inflammation)
Période du rapport: 2023-07-01 au 2023-12-31
Preserving skin homeostasis depends on complex interactions among structural cells, immune cells, and the environment. Dysregulation of this delicate equilibrium contributes to the development of type 2 immunity-associated skin inflammation (i.e. allergic skin inflammation), including atopic dermatitis (AD). The skin is a complex organ harboring various tissue-resident immune cells (e.g. dendritic cells, mast cells and macrophages) and innervated by a meshwork of sensory nerves, including those involved in nociception (i.e. nociceptors), which respond to injurious or potentially damaging stimuli by transmitting signals to the spinal cord and brain. Despite their role in the transmission of sensation, recent evidences have suggested that nociceptors could be powerful regulators of ongoing immune response.
We used sophisticated mouse models and new in vivo imaging approaches to define the roles of subsets of dermal nociceptors, cationic neuropeptide substance P, dermal mast cells expressing the recently discovered receptor for cationic molecules Mas-related G protein-coupled receptors b2 (i.e. Mrgprb2), in a mouse model of AD that has many pathological, immunological, and gene expression similarities with the corresponding human disorder. We also will define the translational relevance of our mouse studies by performing parallel analyzes of nociceptors and mast cells in the lesional skin of patients from USA and France with clinically-established AD. To accomplish these goals, we have proposed herein a body of work that is solidly based on our preliminary data, with four Aims that will test innovative hypotheses by using informative genetic approaches, as well as new intravital imaging systems we recently developed. This work thus will address significant gaps in our knowledge about the pathophysiology of AD and has the potential to identify such neuro-immune interactions as a promising new therapeutic target in AD and perhaps other allergic disorders.
We used sophisticated mouse models and new in vivo imaging approaches to define the roles of subsets of dermal nociceptors, cationic neuropeptide substance P, dermal mast cells expressing the recently discovered receptor for cationic molecules Mas-related G protein-coupled receptors b2 (i.e. Mrgprb2), in a mouse model of AD that has many pathological, immunological, and gene expression similarities with the corresponding human disorder. We also will define the translational relevance of our mouse studies by performing parallel analyzes of nociceptors and mast cells in the lesional skin of patients from USA and France with clinically-established AD. To accomplish these goals, we have proposed herein a body of work that is solidly based on our preliminary data, with four Aims that will test innovative hypotheses by using informative genetic approaches, as well as new intravital imaging systems we recently developed. This work thus will address significant gaps in our knowledge about the pathophysiology of AD and has the potential to identify such neuro-immune interactions as a promising new therapeutic target in AD and perhaps other allergic disorders.
Combining new imaging approaches and various genetic models, we showed that exposure to domestic allergens trigger the activation of MC-nociceptor functional knots in the skin, which represents a key early event regulating the development of allergic skin inflammation. We used an AD-like mouse model displaying moderate to severe AD-like lesions and featuring pathological traits similar to human AD. In vivo ablation of TRPV1+ neurons, deletion of Tac1 gene or genetic inactivation of the MC-restricted cationic receptor MRGPRB2 significantly reduced the development of allergic skin inflammation and its associated features, highlighting a substantial role for MRGPRB2+ MCs and Substance P-producing sensory neurons in the pathology. Using intravital imaging in living genetically modified mice, we also observed that activated TRPV1+ Tac1+ nociceptors induced the degranulation of contiguous MCs in the skin, through the release of substance P and consequent activation of MRGPRB2. These results were published in Nature Immunology in the article entitled ‘House dust mites activate nociceptor-mast cell clusters to drive type 2 skin inflammation’. In continuity with these results, we have initiated the design of new therapeutic molecules in order to hopefully treat AD in humans.
We then further characterized those MCs in mice and humans across organs. Through whole-tissue imaging and single-cell RNA sequencing, we identified two distinct MC populations in mice: MrgprB2+ connective tissue MCs, which develop in utero independent of bone marrow, and MrgprB2neg mucosal MCs, developing postnatally and renewed by bone marrow progenitors. In humans, seven MC subsets (MC1–6) were identified across 12 organs, each with distinct transcriptomic profiles. This study reveals significant diversity of MC subtypes in mice and humans. These findings were published in 2023 in the "Journal of Experimental Medicine" and were entitled: "Landscape of mast cells across organs in mice and humans".
Finally, in order to investigate neuroimmune interactions in human samples we generated a new imaging method. Routine clinical assays, such as conventional immunohistochemistry, often fail to resolve the regional heterogeneity of complex inflammatory skin conditions. We developed MANTIS (Multiplex Annotated Tissue Imaging System), a flexible analytic pipeline compatible with routine practice, specifically designed for spatially resolved immune phenotyping of the skin in experimental or clinical samples. On the basis of phenotype attribution matrices coupled to α-shape algorithms, MANTIS projects a representative digital immune landscape while enabling automated detection of major inflammatory clusters and concomitant single-cell data quantification of biomarkers. We observed that severe pathological lesions from systemic lupus erythematosus, Kawasaki syndrome, or COVID-19–associated skin manifestations share common quantitative immune features while displaying a nonrandom distribution of cells with the formation of disease-specific dermal immune structures. Given its accuracy and flexibility, MANTIS is designed to solve the spatial organization of complex immune environments to better apprehend the pathophysiology of skin manifestations. These findings were published in "Science Advances" in 2023 and are entitled "3D deconvolution of human skin immune architecture with Multiplex Annotated Tissue Imaging System".
We then further characterized those MCs in mice and humans across organs. Through whole-tissue imaging and single-cell RNA sequencing, we identified two distinct MC populations in mice: MrgprB2+ connective tissue MCs, which develop in utero independent of bone marrow, and MrgprB2neg mucosal MCs, developing postnatally and renewed by bone marrow progenitors. In humans, seven MC subsets (MC1–6) were identified across 12 organs, each with distinct transcriptomic profiles. This study reveals significant diversity of MC subtypes in mice and humans. These findings were published in 2023 in the "Journal of Experimental Medicine" and were entitled: "Landscape of mast cells across organs in mice and humans".
Finally, in order to investigate neuroimmune interactions in human samples we generated a new imaging method. Routine clinical assays, such as conventional immunohistochemistry, often fail to resolve the regional heterogeneity of complex inflammatory skin conditions. We developed MANTIS (Multiplex Annotated Tissue Imaging System), a flexible analytic pipeline compatible with routine practice, specifically designed for spatially resolved immune phenotyping of the skin in experimental or clinical samples. On the basis of phenotype attribution matrices coupled to α-shape algorithms, MANTIS projects a representative digital immune landscape while enabling automated detection of major inflammatory clusters and concomitant single-cell data quantification of biomarkers. We observed that severe pathological lesions from systemic lupus erythematosus, Kawasaki syndrome, or COVID-19–associated skin manifestations share common quantitative immune features while displaying a nonrandom distribution of cells with the formation of disease-specific dermal immune structures. Given its accuracy and flexibility, MANTIS is designed to solve the spatial organization of complex immune environments to better apprehend the pathophysiology of skin manifestations. These findings were published in "Science Advances" in 2023 and are entitled "3D deconvolution of human skin immune architecture with Multiplex Annotated Tissue Imaging System".
This project aims to explore the multifaceted aspect of AD pathology, by analyzing the role of interactions between primary sensory neurons (regulating itching sensation in patients), immune system and skin barrier proteins (both suspected to contribute to disease development) in regulating AD-like features. By using such experimental design, we aim to build a synergy between neurobiology, immunology and clinical dermatology and contribute to pave the way toward better understanding of this complex disease.
The proposed project is scientifically and technologically innovative because it integrates the most powerful genetic and imaging approaches in neuro-immunology, and because it directly addresses key medical questions using a relevant mouse model of AD with pathophysiology and gene expression profile similar to that in human AD. We expect that this project will make several key advancements in our perception of the contribution of nerve/MC interactions in the regulation of type 2 immunity and skin lesions. While sensory neurons are usually studied in the context of their primary functions (i.e. the transmission of sensations), the project proposed herein aims to: (1) reveal a previously unsuspected important role played by Trpv1+, Tac1+ (SP-producing subset) of nociceptors in the development of skin pathology and associated type 2 immunity that are similar to those observed in human AD; (2) identify Mrgprb2 as a key receptor involved in this process; (3) define Mrgprb2+ MCs as a unique MC subset able to interact with Trpv1+, Tac1+ sensory neurons; and (4) explore the human relevance of these findings by assessing nerve/MC interactions in patients diagnosed with AD; and (5) develop new therapeutic opportunities.
Finally, èhis project enabled to unbiasedly characterize MC diversity across organs in mice and humans to foster the development of personalized therapeutic approaches to treat disorders in which MCs and neurons are involved.
The proposed project is scientifically and technologically innovative because it integrates the most powerful genetic and imaging approaches in neuro-immunology, and because it directly addresses key medical questions using a relevant mouse model of AD with pathophysiology and gene expression profile similar to that in human AD. We expect that this project will make several key advancements in our perception of the contribution of nerve/MC interactions in the regulation of type 2 immunity and skin lesions. While sensory neurons are usually studied in the context of their primary functions (i.e. the transmission of sensations), the project proposed herein aims to: (1) reveal a previously unsuspected important role played by Trpv1+, Tac1+ (SP-producing subset) of nociceptors in the development of skin pathology and associated type 2 immunity that are similar to those observed in human AD; (2) identify Mrgprb2 as a key receptor involved in this process; (3) define Mrgprb2+ MCs as a unique MC subset able to interact with Trpv1+, Tac1+ sensory neurons; and (4) explore the human relevance of these findings by assessing nerve/MC interactions in patients diagnosed with AD; and (5) develop new therapeutic opportunities.
Finally, èhis project enabled to unbiasedly characterize MC diversity across organs in mice and humans to foster the development of personalized therapeutic approaches to treat disorders in which MCs and neurons are involved.