Granzyme B Contributes to Barrier Dysfunction in Oxazolone-Induced Skin Inflammation through E-Cadherin and FLG Cleavage

Abstract

Atopic dermatitis (AD) is the most common inflammatory skin condition. Skin barrier dysfunction is of major importance in AD because it facilitates allergen sensitization and systemic allergic responses. Long regarded as a pro-apoptotic protease, emerging studies indicate granzyme B (GzmB) to have extracellular roles involving the proteolytic cleavage of extracellular matrix, cell adhesion proteins, and basement membrane proteins. Minimally expressed in normal skin, GzmB is elevated in AD and is positively correlated with disease severity and pruritus. We hypothesized that GzmB contributes to AD through extracellular protein cleavage. A causative role for GzmB was assessed in an oxazolone-induced murine model of dermatitis, comparing GzmB À/À mice with wild-type mice, showing significant reductions in inflammation, epidermal thickness, and lesion formation in GzmB À/À mice. Topical administration of a small-molecule GzmB inhibitor reduced disease severity compared with vehicle-treated controls. Mechanistically, GzmB impaired epithelial barrier function through Ecadherin and FLG cleavage. GzmB proteolytic activity contributes to impaired epidermal barrier function and represents a valid therapeutic target for AD.

Dual roles of granzyme B

“…108 Turner et al confirmed that GZMB impaired the epithelial barrier function through Ecadherin and filaggrin cleavage, and VTI-1002 reduced the severity of skin barrier dysfunction in atopic dermatitis (the most commonly occurring inflammatory skin condition). 94 These studies suggest the therapeutic potential of VTI-1002 for GZMB-induced/aggravated diseases. PI-9 is an endogenous GZMB inhibitor that can bind to GZMB in the cytosol of activated CD8 + T cells.…”

“…16 Turner et al have confirmed that GZMB contributes to barrier dysfunction in oxazoloneinduced skin inflammation through E-cadherin and filaggrin cleavage. 94 GZMB also induces the cleavage of membraneassociated guanylate kinases (MAGUKs); MAGUKs constitute a family of proteins that are typically associated with cell junctions and play a major role in the organization of proteinprotein complexes in plasma membranes. GZMB-mediated cleavage of MAGUKs (including membrane-associated guanylate kinase with inverted orientation protein (MAGI)-1, MAGI-2, MAGI-3, disc large homolog 1, post-synaptic density (PSD)-95, PSD-93, synapse-associated protein 102, zonula occludens (ZO)-1 and ZO-3) in vitro demonstrates its importance in the rapid and proper disruption of cell-cell contacts and in the isolation of a dying cell during apoptosis.…”

“…Additionally, GZMB that enters the cells mainly plays a significant role in eliminating tumour cells/virus-infected cells, [27][28][29][37][38][39][40]44 eliminating intracellular bacteria and parasites, 19,20,41,42 and viruses. [46][47][48][49][50] However, extracellular GZMB plays an important role in inducing the occurrence and development of diseases (such as inflammation, 8,84,[93][94][95][96][97][98][99] fibrosis, 88,115 CAV, 83 AAA, 89 autoimmune blistering diseases, 92,93,108 age-related macular degeneration, 16 SLE/LN, 109 RA, 4 SSPE, 110 cardiovascular disease, [112][113][114] and wound healing [117][118][119][120] ).…”

γδ intraepithelial lymphocytes facilitate pathological epithelial cell shedding via CD103-mediated granzyme release

“…Furthermore, granzymes A and B contributed to LPS-induced cell shedding in a perforin-independent manner, providing strong evidence that gd IELs facilitate cell shedding through a mechanism other than direct lysis. Extracellular granzyme has been shown to promote the proteolytic cleavage of ECM proteins such as laminin, type IV collagen, and fibronectin, which are found in the intestinal BM [53][54][55][56][57][58][59] . This has been shown to contribute to cell death, as GzmB-mediated matrix remodeling can induce the detachment and apoptosis of cultured endothelial and transformed epithelial cells 56 .…”

Comparative Study on Different Skin Pruritus Mouse Models

“…Although the cause of the itch was complicated, there were still some common factors that existed. Multiple immune cells participate in pruritus of the irritated itch model mice, including mast cells and CD4 + and CD8 + T lymphocytes (31,32). Like keratinocytes, mast cells are a major source of cutaneous proinflammatory mediators thought to underlie the pathology of pruritus, most importantly IL-33, IL-4, and IL-13 (29,33,34).…”