Single-cell immunophenotyping of the skin lesion erythema migrans identifies IgM memory B cells

Abstract

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 to autologous uninvolved skin; many were clonally expanded and had circulating relatives. EM-associated B cells upregulated 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 express a phenotype consistent with local antigen presentation and antibody production.

Tick feeding modulates the human skin immune landscape to facilitate tick-borne pathogen transmission

“…Frequencies of CD14 + mononuclear phagocytes, CD11b + CD68 + macrophages, and CD11b – CD123 + plasmacytoid DCs (pDCs) remained unchanged ( Figure 1C ). Further diagnostic features of early Borrelia skin infection are increased cutaneous B cell numbers and a plasma cell infiltrate ( 27 ). Interestingly, we detected significantly increased B cell frequencies in the skin after a TB without Borrelia transmission, while plasma cell levels remained unchanged ( Figure 1D ).…”

Single‐cell transcriptomics in human skin research: available technologies, technical considerations and disease applications

“…Samples of erythema migrans, a skin rash and initial sign of Lyme disease, were analysed with scRNA and B‐cell receptor sequencing. Increased numbers of B cells with MHC class II upregulated genes, as well as memory B cells with IgM receptors, were found pointing to local antibody production at the skin infection site 60 . By combining scRNA‐seq with spatial transcriptomics, Ma et al constructed the cellular network of the antimicrobial response in leprosy granulomas 61 …”

“…Increased numbers of B cells with MHC class II upregulated genes, as well as memory B cells with IgM receptors, were found pointing to local antibody production at the skin infection site. 60 By combining scRNA-seq with spatial transcriptomics, Ma et al constructed the cellular network of the antimicrobial response in leprosy granulomas. 61 Mφ were predominantly located at the centre of the granuloma and were surrounded by lymphocytes and distinct fibroblast subpopulations.…”

Research progress on application of single-cell TCR/BCR sequencing technology to the tumor immune microenvironment, autoimmune diseases, and infectious diseases

“…B-cell cloning and amplification in the skin of EM patients and the expression of MHC class II genes in EM-associated B cells are upregulated. This provides a direction for revealing the mechanism of immune responses in borrelia infection ( 26 ). The application of single-cell TCR/BCR sequencing technology to infectious disease research is summarized in Table 2 .…”