Fibroblasts with high matrix metalloproteinase 2 expression regulate CD8+ T-cell residency and inflammation via CD100 in psoriasis.

ABSTRACT

BACKGROUND: Psoriasis is a T cell-mediated chronic inflammatory skin condition characterized by the interaction of T cells with various cell types, forming an inflammatory microenvironment that sustains psoriatic inflammation. Homeostasis of these tissue-resident T cells is supported by fibroblasts, the primary structural cells in the dermis. In psoriasis, there is increased expression of matrix metalloproteinase 2 (MMP2), mediating structural alterations in skin tissues and modulating inflammation. Additionally, the CD100-plexin-B2 (PLXNB2) axis is known to enhance psoriasis inflammation via keratinocytes, and CD103 levels are associated with the severity of psoriasis upon relapse. OBJECTIVES: To elucidate the role of fibroblasts and the MMP2-CD100 axis in modulating psoriasis inflammation. METHODS: CD100 expression and function in psoriasis were assessed using immunofluorescence, enzyme-linked immunosorbent assay, single-cell transcriptome sequencing, cellular interaction analyses and quantitative reverse transcriptase polymerase chain reaction. CD8+ T cells from people with psoriasis were isolated using magnetic beads, to investigate the regulatory effect of MMP2 on CD100 expression on their membranes. Single-cell transcriptome sequencing, spatial transcriptome sequencing, mimetic timing analysis, immunofluorescence and flow cytometry were used to determine the origin of MMP2 and its impact on CD103+ CD8+ T cells. The hypotheses were further validated in vivo using MMP2 and CD100 inhibitors. RESULTS: Soluble CD100 (sCD100) was significantly upregulated in both psoriatic lesions and peripheral blood, amplifying psoriasis inflammation by promoting the production of inflammatory cytokines by keratinocytes, fibroblasts and endothelial cells via the sCD100-PLXNB2 axis. Fibroblasts that highly expressed MMP2 (MMP2hi) exacerbated psoriasis symptoms by facilitating CD100 shedding from CD8+ T-cell membranes. Additionally, it was shown that fibroblasts enhance the upregulation of the CD8+ T-cell residency factor CD103 in co-cultures with CD8+ T cells. Inhibitors targeting MMP2 and CD100 were effective in reducing inflammation in an imiquimod-induced psoriasis model. CONCLUSIONS: Our findings underscore the pivotal role of MMP2hi fibroblasts in the amplification and recurrence of inflammatory responses in psoriasis. These fibroblasts augment psoriasis inflammation through the CD100-PLXNB2 axis by facilitating CD100 shedding on CD8+ T-cell membranes and by upregulating CD103, thereby enhancing CD8+ T-cell residency.

Psoriasis is a chronic skin condition. It involves the interaction of cells of the immune system (called T cells) with other cells in the body, causing inflammation. The main structural cells in the skin are called fibroblasts. Fibroblasts are important in skin healing and disease. In psoriasis, the body produces more of an enzyme called MMP2. MMP2 brings about structural alterations in skin tissues and controls inflammation. Proteins called CD100 and PLXNB2 increase the inflammation in psoriasis through another type of skin cell called keratinocytes. We investigated the role of fibroblasts and MMP2 and CD100 in psoriasis. To do this, the production and function of CD100 were assessed using a variety of laboratory techniques. We found that by controlling the enzymes MMP2 and MMP9, fibroblasts cause the release of CD100 from some T cells, encouraging the production of substances that promote inflammation, worsening psoriasis. This also caused fibroblasts to produce more MMP2, forming a cycle that increases the inflammation seen in psoriasis. Fibroblasts were found to increase the level of another protein called CD103 on some T cells, affecting how often psoriasis flares up. Our study highlights the important role of fibroblasts that express a lot of MMP2 in the inflammation found in people with psoriasis.