Clostridium perfringens, an anaerobic endospore-forming Gram-positive bacterium, causes multiple intestinal diseases of humans and livestock[1]. The virulence of C. perfringens is dependent on the presence of more than 20 potent toxins. The major toxins are alpha toxin (CPA), beta toxin (CPB), C. perfringens enterotoxin (CPE), epsilon toxin (ETX), Iota toxin (ITX), and necrotic enteritis B-like toxin (NetB), which categorize C. perfringens into seven toxinotypes including type A-G (Table 1).Toxins have been the traditional focus of C. perfringens research, which cause intestinal epithelial cell damage through different mechanisms[2]. The following section will discuss in detail the mechanisms of cell damage caused by toxins of C. perfringens, including damage to the intestinal barrier and induction of cell death.

The intestinal epithelial cells (IECs) form a dynamic, permeable barrier allowing for selective absorption of nutrients while restricting the invasion of pathogens[5]. The precise regulation of epithelial barrier function maintains mucosal homeostasis, ensuring a balance between pro- and anti-inflammatory mucosal factors and the integrity of epithelial elements. IECs are interconnected by a complex of intercellular junctions, including tight junctions (TJs), adherens junctions, desmosomes, and gap junctions[6]. Among these, TJs are the most apical and crucial for maintaining intestinal barrier integrity, forming a complex consisting of transmembrane proteins, cytoplasmic plaque proteins, signaling proteins, and adapters that link them to the actin cytoskeleton. TJs serve as the first line of defense against pathogen invasion from the intestinal lumen to the sterile underlying tissues. In both in vivo/vitro models of infections, the rapid proliferation of C. perfringens correlates with increased intestinal permeability. Studies have evaluated the integrity of TJ proteins primarily through Western blot and microscopy analyses during IEC infections, revealing outcomes such as altered cell distribution, modified gene expression, or changes in protein levels, as discussed later.

An abnormal increase in IEC death rates is a characteristic feature of intestinal diseases, often linked to widespread epithelial erosion. C. perfringens toxins typically attach to plasma membrane receptors on target cells, triggering intracellular pathways that induce various cytopathic effects and eventually lead to cell death. In addition to classic necrosis and apoptosis, many pathogens, including C. perfringens, can activate additional cell death pathways such as necroptosis, autophagy, pyroptosis, and anoikis[7]. Cell apoptosis induced by C. perfringens is strongly linked to the level of ROS, which can promote cell survival and proliferation at low doses but induce apoptosis at higher doses[8], [9]. The imbalance between ROS generation and endogenous antioxidant defense causes oxidative stress in cells, leading to lipid peroxidation, protein nitration, DNA damage, disruption of mitochondrial structure and function, and ultimately promoting cell apoptosis.[10], [11].

Furthermore, this review will provide a brief update on recent findings regarding non-toxin factors, such as degradative enzymes and adhesins, which are now recognized to contribute to the pathogenicity of this bacterium. Additionally, we will discuss the subsequent inflammation resulting from cell damage.