Project description:The skin lesion erythema migrans (EM) is the first clinical sign of Lyme disease, an infection due to the tick-transmitted bacterium Borrelia burgdorferi (Bb). Previously we used single cell transcriptomics with B cell and T cell receptor sequencing to characterize the cutaneous immune response in the EM lesion, focusing on B cells. Here, in an expanded sample size, we profiled T cell responses in the EM lesions in comparison to autologous uninvolved skin. In addition to CD4+IFNG+ T cell subsets known to be abundant in the EM, we identified clonal expansion of CD8+GZMK+IFNG+ T cells that comprised the only T cell population with significant differential expression of interferon regulated genes. This subset included IFNG+ cells with low cytotoxic gene expression, which may promote inflammation. While FOXP3+ regulatory T cells also were increased in EM, we found that the CD4+FOXP3- effector T cell subset contained cells with the highest differential expression of IL-10. Fibroblasts, endothelial cells, and pericytes expressed a broader array of chemokines than macrophages. These studies represent the first comprehensive interrogation of the cutaneous T cell response to Bb infection using single cell transcriptomics and provide insight into the orchestration of the skin immune response to this vector-borne pathogen.
Project description:The skin lesion erythema migrans (EM) is the first clinical sign of Lyme disease, an infection due to the tick-transmitted bacterium Borrelia burgdorferi (Bb). Previously we used single cell transcriptomics with B cell and T cell receptor sequencing to characterize the cutaneous immune response in the EM lesion, focusing on B cells. Here, in an expanded sample size, we profiled T cell responses in the EM lesions in comparison to autologous uninvolved skin. In addition to CD4+IFNG+ T cell subsets known to be abundant in the EM, we identified clonal expansion of CD8+GZMK+IFNG+ T cells that comprised the only T cell population with significant differential expression of interferon regulated genes. This subset included IFNG+ cells with low cytotoxic gene expression, which may promote inflammation. While FOXP3+ regulatory T cells also were increased in EM, we found that the CD4+FOXP3- effector T cell subset contained cells with the highest differential expression of IL-10. Fibroblasts, endothelial cells, and pericytes expressed a broader array of chemokines than macrophages. These studies represent the first comprehensive interrogation of the cutaneous T cell response to Bb infection using single cell transcriptomics and provide insight into the orchestration of the skin immune response to this vector-borne pathogen.
Project description:The skin lesion erythema migrans (EM) is an initial sign of the Ixodes tick-transmitted Borreliella spirochetal infection known as Lyme disease. T cells and innate immune cells have previously been shown to predominate the EM lesion and promote the reaction. Despite the established importance of B cells and antibodies in preventing infection, the role of B cells in the skin immune response to Borreliella is unknown. Here, we used single-cell RNA-Seq in conjunction with B cell receptor (BCR) sequencing to immunophenotype EM lesions and their associated B cells and BCR repertoires. We found that B cells were more abundant in EM in comparison with autologous uninvolved skin; many were clonally expanded and had circulating relatives. EM-associated B cells upregulated the expression of MHC class II genes and exhibited preferential IgM isotype usage. A subset also exhibited low levels of somatic hypermutation despite a gene expression profile consistent with memory B cells. Our study demonstrates that single-cell gene expression with paired BCR sequencing can be used to interrogate the sparse B cell populations in human skin and reveals that B cells in the skin infection site in early Lyme disease expressed a phenotype consistent with local antigen presentation and antibody production.
Project description:Erythema migrans (EM) is a skin lesion caused by the spirochete B. burgdorferi (Bb) and is a hallmark initial sign of Lyme disease. Previous studies have demonstrated that T cells and innate immune cells mediate local inflammatory cytokine production that promote the reaction. Despite the established importance of B cells and antibodies in preventing Bb infection and resolving disease, the role of B cells in the skin immune response to Bb is incompletely defined. In this study, we characterized the immunophenotype of EM lesions and used single cell RNA-Seq to investigate B cell receptor (BCR) and T cell receptor (TCR) repertoires in the EM skin lesions and peripheral blood of patients with Lyme disease. We hypothesized that B cells from the circulation, potentially primed by exposure to Bb antigens in regional draining lymph nodes, are recruited into EM lesions and play an active role in the local response to infection. We found that B cells are more abundant in the EM lesion in comparison to autologous uninvolved skin and possess distinct characteristics, including abundant expression of MHCII genes and preferential IgM isotype usage. A subset exhibited low levels of somatic hypermutation despite a gene expression profile more consistent with memory than naïve B cell subsets. Moreover, infiltrating B cells were clonally expanded and a large fraction could be directly traced to circulating relatives. By leveraging single cell gene expression with paired BCR and TCR repertoire sequencing, we demonstrate, for the first time, that B cells are recruited to the skin infection site in early Lyme disease and express a phenotype suggesting that they could play a role in local antigen presentation and antibody production.
Project description:Erythema migrans (EM) is a skin lesion caused by the spirochete B. burgdorferi (Bb) and is a hallmark initial sign of Lyme disease. Previous studies have demonstrated that T cells and innate immune cells mediate local inflammatory cytokine production that promote the reaction. Despite the established importance of B cells and antibodies in preventing Bb infection and resolving disease, the role of B cells in the skin immune response to Bb is incompletely defined. In this study, we characterized the immunophenotype of EM lesions and used single cell RNA-Seq to investigate B cell receptor (BCR) and T cell receptor (TCR) repertoires in the EM skin lesions and peripheral blood of patients with Lyme disease. We hypothesized that B cells from the circulation, potentially primed by exposure to Bb antigens in regional draining lymph nodes, are recruited into EM lesions and play an active role in the local response to infection. We found that B cells are more abundant in the EM lesion in comparison to autologous uninvolved skin and possess distinct characteristics, including abundant expression of MHCII genes and preferential IgM isotype usage. A subset exhibited low levels of somatic hypermutation despite a gene expression profile more consistent with memory than naïve B cell subsets. Moreover, infiltrating B cells were clonally expanded and a large fraction could be directly traced to circulating relatives. By leveraging single cell gene expression with paired BCR and TCR repertoire sequencing, we demonstrate, for the first time, that B cells are recruited to the skin infection site in early Lyme disease and express a phenotype suggesting that they could play a role in local antigen presentation and antibody production.
Project description:Erythema migrans (EM) is a skin lesion caused by the spirochete B. burgdorferi (Bb) and is a hallmark initial sign of Lyme disease. Previous studies have demonstrated that T cells and innate immune cells mediate local inflammatory cytokine production that promote the reaction. Despite the established importance of B cells and antibodies in preventing Bb infection and resolving disease, the role of B cells in the skin immune response to Bb is incompletely defined. In this study, we characterized the immunophenotype of EM lesions and used single cell RNA-Seq to investigate B cell receptor (BCR) and T cell receptor (TCR) repertoires in the EM skin lesions and peripheral blood of patients with Lyme disease. We hypothesized that B cells from the circulation, potentially primed by exposure to Bb antigens in regional draining lymph nodes, are recruited into EM lesions and play an active role in the local response to infection. We found that B cells are more abundant in the EM lesion in comparison to autologous uninvolved skin and possess distinct characteristics, including abundant expression of MHCII genes and preferential IgM isotype usage. A subset exhibited low levels of somatic hypermutation despite a gene expression profile more consistent with memory than naïve B cell subsets. Moreover, infiltrating B cells were clonally expanded and a large fraction could be directly traced to circulating relatives. By leveraging single cell gene expression with paired BCR and TCR repertoire sequencing, we demonstrate, for the first time, that B cells are recruited to the skin infection site in early Lyme disease and express a phenotype suggesting that they could play a role in local antigen presentation and antibody production.