INTRODUCTION
Cell death is a physiological event essential for homeostasis in multicellular organisms. However, it is also implicated in multiple pathological conditions such as neurodegenerative and ischemic disorders, cancer, auto-inflammatory and autoimmune diseases (Allam, Kumar, Darisipudi, & Anders, 2014; Godlewski & Kobylińska, 2016; Linkermann, Stockwell, Krautwald, & Anders, 2014). Consequently, cell death is tightly regulated by a strict biochemical program which depends on regulatory pathways and protein interaction networks. This programmed cell death (PCD) exhibits various types or modalities, according to the stimulus that triggers it and the molecular pathways that result activated (Galluzzi et al., 2018; Pasparakis & Vandenabeele, 2015). The multiple forms of PCD are in constant update by recent findings in this field, which are revealing the connections and molecular crosstalk between cell death programs, as well as their implication in a wide variety of biological processes (Yan, Elbadawi, & Efferth, 2020).
PCD is involved in several physiological functions such as organ development, tissue remodeling and epithelial cell renewal. It is also essential for cellular homeostasis and cell response to stress, acting as an intrinsic mechanism to prevent malignant transformation and cancer development (Godlewski & Kobylińska, 2016). In addition to its role in tissue maintenance, PCD is a crucial biological response for immunity and host defense. It is part of various innate and adaptive immune mechanisms/processes such as antiviral defense, killing of intracellular pathogens, inflammation, chemoattraction, lymphocyte selection and immune tolerance (Miao, Rajan, & Aderem, 2011; Sumpter Jr & Levine, 2010; Zhou & Fang, 2019). Increasing evidence is revealing novel functions of different cell death types in innate immunity, including the regulation and/or amplification of the inflammatory response, the modulation of cytokine production and release, as well as diverse microbe-killing strategies in specialized immune cells (Andrade & Darrah, 2013; Burgener & Schroder, 2020; H. Chen, Ning, & Jiang, 2017; Humphries, Yang, Wang, & Moynagh, 2015). This review will be focus in important findings that highlight the interconnection between various forms of PCD and their roles in innate immunity.