Intraepithelial mast cells drive gasdermin C-mediated type 2 immunity.

A specialized population of mast cells residing within epithelial layers, currently known as intraepithelial mast cells (IEMCs), was originally observed over a century ago, yet their physiological functions have remained enigmatic. In this study, we unveil an unexpected and crucial role of IEMCs in driving gasdermin C-mediated type 2 immunity. During helminth infection, αEß7 integrin-positive IEMCs engaged in extensive intercellular crosstalk with neighboring intestinal epithelial cells (IECs). Through the action of IEMC-derived proteases, gasdermin C proteins intrinsic to the epithelial cells underwent cleavage, leading to the release of a critical type 2 cytokine, interleukin-33 (IL-33). Notably, mast cell deficiency abolished the gasdermin C-mediated immune cascade initiated by epithelium. These findings shed light on the functions of IEMCs, uncover a previously unrecognized phase of type 2 immunity involving mast cell-epithelial cell crosstalk, and advance our understanding of the cellular mechanisms underlying gasdermin C activation.

The expression profile of Gasdermin C-related genes predicts the prognosis and immunotherapy response of pancreatic adenocarcinoma.

Pancreatic adenocarcinoma (PAAD) has a poor prognosis and is relatively unresponsive to immunotherapy. Gasdermin C (GSDMC) induces pyroptosis in cancer cells and inflammation in the tumor microenvironment. However, whether GSDMC expression in PAAD is associated with survival or response to immunotherapy remains unknown. GSDMC expression and the relationship between GSDMC and patient survival or immune infiltration in PAAD were examined using data in the The Cancer Genome Atlas (TCGA), Gene Expression Ominbus (GEO), Genotype-Tissue Expression (GTEx) and Cancer Cell Line Encyclopedia (CCLE) databases. The TCGA PAAD cohort could be divided into two distinct risk groups based on the expression of GSDMC-related genes (GRGs). The TIDE algorithm predicted that the low-risk group was more responsive to immune checkpoint blockade therapy than the high-risk group. A novel 15-gene signature was constructed and could predict the prognosis of PAAD. In addition, the 15-gene signature model predicted the infiltration of immune cells and Immune checkpoint blockade (ICB) treatment response. Immunohistochemical staining assessment of patient-derived human tissue microarray (TMA) from 139 cases of local PAAD patients revealed a positive correlation between GSDMC expression and PD-L1 expression but a negative correlation between GSDMC expression and infiltration of low CD8+ T cells. Moreover, the overexpression of GSDMC was related to poor overall survival (OS). This study suggests that GSDMC is a valuable biomarker for predicting PAAD prognosis and predicts the immunotherapy response of PAAD.

Detection of Gasdermin C-Mediated Cancer Cell Pyroptosis.

Gasdermin proteins except DFNB59 are the executioners of pyroptotic cell death. Cleavage of a gasdermin by an active protease causes lytic cell death. Gasdermin C (GSDMC) is cleaved by caspase-8 in response to macrophage-secreted TNF-α. Upon cleavage, the GSDMC-N domain is liberated and oligomerized, followed by pore formation in the plasma membrane. GSDMC cleavage, LDH release, and plasma membrane translocation of GSDMC-N domain are the reliable markers for GSDMC-mediated cancer cell pyroptosis (CCP). Here, we describe the methods for examining GSDMC-mediated CCP.

Pyroptosis, inflammasome, and gasdermins in tumor immunity.

The gasdermins (GSDM), a family of pore-forming proteins, consist of gasdermin A (GSDMA), gasdermin B (GSDMB), gasdermin C (GSDMC), gasdermin D (GSDMD), gasdermin E (GSDME) and DFNB59 (Pejvakin (PJVK)) in humans. These proteins play an important role in pyroptosis. Among them, GSDMD is the most extensively studied protein and is identified as the executioner of pyroptosis. Other family members have also been implicated in certain cancers. As a unique form of programmed cell death, pyroptosis is closely related to tumor progression, and the inflammasome, an innate immune mechanism that induces inflammation and pyroptosis. In this review, we explore the current developments of pyroptosis, the inflammasome, and especially we review the gasdermin family members and their role in inducing pyroptosis and the possible therapeutic values in antitumor effects.

Intravenous Delivery of Living Listeria monocytogenes Elicits Gasdmermin-Dependent Tumor Pyroptosis and Motivates Anti-Tumor Immune Response.

The facultative intracellular bacterium Listeria monocytogenes (Lmo) has great potential for development as a cancer vaccine platform given its properties. However, the clinical application of Lmo has been severely restricted due to its rapid clearance, compromised immune response in tumors, and inevitable side effects such as severe systemic inflammation after intravenous administration. Herein, an immunotherapy system was developed on the basis of natural red blood cell (RBC) membranes encapsulated Lmo with selective deletion of virulence factors (Lmo@RBC). The biomimetic Lmo@RBC not only generated a low systemic inflammatory response but also enhanced the accumulation in tumors due to the long blood circulation and tumor hypoxic microenvironment favoring anaerobic Lmo colonization. After genome screening of tumors treated with intravenous PBS, Lmo, or Lmo@RBC, it was first found that Lmo@RBC induced extensive pore-forming protein gasdermin C (GSDMC)-dependent pyroptosis, which reversed immunosuppressive tumor microenvironment and promoted a systemic strong and durable anti-tumor immune response, resulting in an excellent therapeutic effect on solid tumors and tumor metastasis. Overall, Lmo@RBC, as an intravenous living bacterial therapy for the selective initiation of tumor pyrolysis, provided a proof-of-concept of live bacteria vaccine potentiating tumor immune therapy.

The generation of PD-L1 and PD-L2 in cancer cells: From nuclear chromatin reorganization to extracellular presentation.

The immune checkpoint blockade (ICB) targeting on PD-1/PD-L1 has shown remarkable promise in treating cancers. However, the low response rate and frequently observed severe side effects limit its broad benefits. It is partially due to less understanding of the biological regulation of PD-L1. Here, we systematically and comprehensively summarized the regulation of PD-L1 from nuclear chromatin reorganization to extracellular presentation. In PD-L1 and PD-L2 highly expressed cancer cells, a new TAD (topologically associating domain) (chr9: 5,400,000-5,600,000) around CD274 and CD273 was discovered, which includes a reported super-enhancer to drive synchronous transcription of PD-L1 and PD-L2. The re-shaped TAD allows transcription factors such as STAT3 and IRF1 recruit to PD-L1 locus in order to guide the expression of PD-L1. After transcription, the PD-L1 is tightly regulated by miRNAs and RNA-binding proteins via the long 3'UTR. At translational level, PD-L1 protein and its membrane presentation are tightly regulated by post-translational modification such as glycosylation and ubiquitination. In addition, PD-L1 can be secreted via exosome to systematically inhibit immune response. Therefore, fully dissecting the regulation of PD-L1/PD-L2 and thoroughly detecting PD-L1/PD-L2 as well as their regulatory networks will bring more insights in ICB and ICB-based combinational therapy.

Gasdermin C is induced by ultraviolet light and contributes to MMP-1 expression via activation of ERK and JNK pathways.

BACKGROUND: Ultraviolet (UV) radiation plays important roles in various skin diseases including premature aging and cancer. UV has been shown to regulate the expressions of many genes including matrix metalloproteinases (MMPs). Gasdermin C (GSDMC) belongs to Gasdermin family and is known to be expressed in the epithelial cells of many tissues including the skin. However, the functions of GSDMC remain poorly understood. OBJECTIVE: We aimed to investigate the role of GSDMC in UV-induced MMP-1, MMP-3, and MMP-9 expressions in human skin keratinocytes. METHODS: Primary human skin keratinocytes and an immortalized human skin keratinocyte cell line (HaCaT cells) were irradiated with UV. Knockdown and overexpression of GSDMC were performed to study the effect of GSDMC. The mRNA and protein levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting, respectively. RESULTS: We found that GSDMC expression is increased by UV irradiation in human skin keratinocytes. Further studies showed that GSDMC expression is increased at relatively late time points after UV irradiation and that this GSDMC induction plays important roles in the expressions of MMP-1, but not of MMP-3 and MMP-9, and the activations of ERK and JNK induced by UV. In addition, we found that overexpression of GSDMC increases the MMP-1 expression and the activities of ERK and JNK and that GSDMC-induced MMP-1 expression is suppressed by inhibition of ERK or JNK activities. CONCLUSIONS: Our results suggest that GSDMC is increased by UV radiation and contributes to UV-induced MMP-1 expression through the activation of ERK and JNK pathways.