Perez White, B. E. | bioRxiv Science

bioRxiv2024

IgG autoantibodies in bullous pemphigoid directly induce a pathogenic MyD88-dependent pro-inflammatory response in keratinocytes:

AbstractWhile autoantibodies in bullous pemphigoid (BP) are known to activate the innate immune response, their direct effect on keratinocytes, and the contribution of BP-IgG autoantibody-dependent keratinocyte responses to BP pathology is largely unknown. Herein, we performed multiplex immunoassays and bulk RNA-seq on primary keratinocytes treated with IgG from BP patients or controls. We identified a pro-inflammatory and proteolytic response with release of several cytokines (IL-6, IL-24, TGF-{beta}1), chemokines (CXCL16, CTACK, MIP-3{beta}, RANTES), C1s, DPP4, and MMP-9. We further validated this response using spatial transcriptomics and scRNA-seq of diseased and control skin. Blistering itself appeared to be major driver of this inflammatory response, with attached BP skin and spongiotic dermatitis revealing highly similar transcriptomes. Based on elevated levels of MyD88 and MyD88-dependent cytokines, we studied the impact of MyD88 deficiency in keratinocytes and demonstrated that MyD88 regulates BP-IgG-induced expression of IL-8, IL-24, and MMP-9. Induction of experimental BP in mice with Krt14-specific Myd88 knockout revealed significantly decreased disease severity with decreased serum levels of IL-1{beta}, IL-4, and IL-9 indicating the contributory role of keratinocyte-derived skin inflammation towards systemic response. Our work demonstrates the key contributions of keratinocyte and MyD88 dependent signaling in response to autoantibodies in BP. Key Messages-IgG antibodies from bullous pemphigoid (BP) patients induce significant upregulation of several inflammatory markers in keratinocytes including cytokines (IL-6, IL-24, TGF-{beta}1), chemokines (CXCL16, CTACK, MIP-3{beta}, RANTES), C1s, DPP4, and MMP9. Several of these markers, including IL-8, IL-24, and MMP9 are regulated by MyD88. -Spatial transcriptomics reveals that BP patient blistered skin demonstrated similar transcriptomic profiles to BP-IgG-treated keratinocytes. With attached skin demonstrating a comparable transcriptome to that seen in spongiotic dermatitis. -In a mouse BP model, keratinocyte-specific MyD88 deficiency results in decreased disease severity with a subsequent decrease in serum IL-1{beta}, IL-4, and IL-9 levels. Capsule summaryIgG from patients with bullous pemphigoid (BP) induces a pro-inflammatory response in keratinocytes, indicating their direct role in driving the inflammatory response in BP.

immunology↗

bioRxiv2022

Nucleoli and the nucleoli-centromere association are dynamic during normal development and in cancer

Centromeres are known to cluster around nucleoli in drosophila and mammalian cells. However, the functional significance of nucleoli-centromere interaction remains underexplored. We hypothesize that if this conserved interaction is functionally important, it should be dynamic under different physiological and pathological conditions. We examined the nucleolar structure and centromeres at various differentiation stages using cell culture models. The results show dynamic changes of nucleolar number, area, and nucleoli-centromere interactions at differentiation stages and in cancer cells. Embryonic stem cells usually have a single large nucleolus, which associates with a high percentage of centromeres. As cells differentiate into intermediate states, the nucleolar number increases and the association with centromeres decreases. In terminally differentiated cells, including myotubes, neurons and keratinocytes, the number of nucleoli and their association with centromeres are at the lowest. Cancer cells demonstrate the pattern of nucleoli number and nucleoli-centromere association that is akin to proliferative less differentiated cell types, suggesting that nucleolar reorganization and changes in nucleoli-centromere interactions may help facilitate malignant transformation. This idea is supported in a case of pediatric rhabdomyosarcoma, in which induced differentiation inhibits cell proliferation and reduces nucleolar number and centromere association. These findings suggest active roles of nucleolar structure in centromere function and genome organization critical for cellular function in both normal development and cancer.

cell biology↗