The first member of the gasdermin family was identified in the upper gastrointestinal tract in 2000 [1]. Up until now, the GSDM family has six members in humans, including GSDMA, GSDMB, GSDMC, GSDMD, GSDME (DFNA5) and PJVK (DFNB59, GSDMF) [2]. In mice, GSDMA has three homologues: GSDMA1–3. GSDMB has no homologue in mice. There are four homologues of GSDMC in mice: GSDMC1–4. GSDMD, GSDME, and PJVK each possesses a single homologue in mice. All GSDMs are capable executors of pyroptosis, except for PJVK. While they have conserved N-terminus (NT) and C-terminus (CT), the linker regions differ, which leads to distinct regulations and functions of GSDMs.

GSDMs play pivotal roles in maintaining intestinal homeostasis. They have been shown to induce inflammatory lytic cell death (e.g., pyroptosis and NETosis), rapid cytokine release without cell death, and other non-cell-lytic functions. The aim of this review is to: (1) provide a comprehensive summary of the expression pattern of GSDMs in the intestine based on current literature and single cell RNA sequencing (scRNA-seq) databases; (2) summarize the regulation, cleavage, and function of GSDMs; and (3) discuss the pathophysiological roles of GSDMs in pathogen-host interactions, inflammatory bowel disease (IBD), and gastrointestinal cancer.

The gut epithelium is a highly regenerative tissue and is replenished every 3–5 days. Considering the translation rate and protein lifetimes, one would predict discordances between mRNA and protein expression in the intestine. Indeed, many genes exhibit mRNA zonated toward the crypt, while proteins are zonated toward the villus, due to delayed protein synthesis [3]. Therefore, caution should be taken when drawing conclusions on intestinal epithelial protein expression and function solely based on mRNA results. For instance, while mouse Gsdmc2–4 mRNA expression is enriched in the transit amplifying (TA) region shown by scRNA-seq and RNAscope, its protein is much more abundant in the villus than the crypt [4]. In addition, we would like to point out that many expression results discussed below were obtained from intestine at homeostatic conditions. Infectious, inflammatory, and tumorigenic environments may vary the expression levels and locations of GSDMs [5].

GSDMs, except PJVK, have been reported or detected at some level in the gastrointestinal (GI) tract. Their expression is mainly found in the epithelium and immune cells, but can also be detected in other cell types including endothelial cells and fibroblasts. In order to decipher the role of individual GSDMs in the intestine, we have to first know which cells express them, at what conditions.

Although the human GSDMA gene was suggested to be expressed in the upper GI tract and suppressed in gastric cancer [1], further study is needed to determine what subpopulations of human intestinal epithelial cells (IECs), if any, express GSDMA.

Mouse Gsdma genes are primarily expressed in epidermal keratinocytes and hair follicle stem cells [6]. In the mouse intestine, based on scRNA-seq results, Gsdma1 is expressed in a cluster of Chgb+ enteroendocrine cells (EECs), Gsdma2 is expressed in a small subset of goblet cells, while Gsdma3 is barely detectable (Table1, 2) [7], [8].

The predominant expression site of human GSDMB is the epithelium of lung, esophagus, intestine, and stomach [9], [10], [11], [12]. scRNA-seq shows that intestinal GSDMB is expressed in stem cells, TA cells and almost all types of differentiated IECs, expect tuft cells and microfold cells (Table 1). In the immune compartment, GSDMB is low expressed by macrophages and T cells [13], [14].

Human GSDMC expression has been reported to be restricted in the epithelium, not any immune cells, of trachea, esophagus, and intestine [4], [12], [15]. According to human scRNA-seq data, GSDMC high-expressing intestinal cells are goblet cells (Table 1), which is consistent with recent reports in mice [4], [16].

In mice, Gsdmc1 is not expressed in the intestine due to epigenetic silencing (Table 2) [4], [16], [17]. Gsdmc4, Gsdmc2, and Gsdmc3 (in the order of their expression levels) can be detected in several types of IECs, including goblet cells, tuft cells, progenitor cells, and enterocytes. It is worth noting that although Gsdmc 2–4 mRNA is enriched in the crypt base and TA region based on sequencing and RNA in situ hybridization [4], [16], [17], immunostaining revealed that GSDMC protein is only abundantly expressed in villous enterocytes [4]. Interestingly, the duplicated Gsdmc2–4 genes in mice display an expression pattern analogous to the human-only GSDMB, suggesting that they might be adopted by the two hosts for similar gut functions (see below).

Human GSDMD (hGSDMD) exhibits global expressions in epithelial cells, neurons, cardiomyocytes, and immune cells [2], [18]. Almost all cell types in the intestine express some level of hGSDMD, including epithelial cells, fibroblasts, smooth muscle cells, as well as innate and adaptive immune cells (Table 1, Table 2).

The expression pattern of mouse GSDMD (mGSDMD) is similar to hGSDMD, but some notable differences exist between mice and humans. Mouse GSDMD expression in mast cells is significantly higher than hGSDMD, while in goblet cells, tuft cells, epithelial stem cells and progenitor cells is much lower than that of human. When investigating the function of GSDMD using mouse models, these expression differences should be considered.

Human GSDME (hGSDME), also known as DFNA5, was first discovered as a deafness associated gene in the epithelium of cochlea [19]. In the epithelium of intestine, stomach, and esophagus, hGSDME is also highly expressed [20], [21]. In the IECs, human GSDME gene expression is only found in enterocytes and goblet cells (Table 1). Outside of the epithelium, hGSDME is expressed in the endothelium of blood vessels and various immune cells, including B cells, macrophages, and monocytes [2], [22], [23].

Mouse Gsdme is expressed in enterocytes and goblet cells, at a level seemingly higher that of human GSDME, as well as in EECs. Most murine immune cells, including B cells, T cells, mast cells, neutrophils, dendritic cells (DCs), macrophages, and monocytes, express Gsdme. Intriguingly, both Gsdmd and Gsdme are abundantly expressed by mast cells in mice but not in humans, which may contribute to species-specific roles of mast cells in various biological responses. Furthermore, mouse Gsdme is also expressed by glial cells, fibroblasts, and pericytes, implicating their broad and impactful roles.

The cell-type specific expression will provide a new perspective to dissect the role of GSDMs in the intestine. While gene expression data become more abundantly available, we still lack knowledge of the protein expression and localization of most GSDMs, particularly during disease states. Moreover, the gut is highly compartmentalized in terms of structure (duodenum, jejunum, ileum, and colon), microbial and immune compositions, and function. Many studies on GSDMs only focused on one specific part of the intestine. Spatiotemporal analysis of GSDM distribution and expressional regulation will shed light on their functional roles.