S100A8和S100A9是炎症过程的钙结合调节剂和免疫应答（也知道迁移抑制因子相关蛋白8（MRP8）和MRP14）。S100A8和S100A9在嗜中性粒细胞，髓样衍生的树枝状细胞，血小板，骨质体和肥大软骨细胞（Hessian Pa等，1993; Kumar A等人2003; Healy Am等，2006; Schelbergen Rf等，2012）。相反，这些分子在单核细胞/巨噬细胞，微血管内皮细胞，角质形成细胞和成纤维细胞中诱导炎症刺激（Hessian Pa等，1993; Eckert Rl等，2004; viemann d等人2005; mccormick mm等，2005; HSU K等人。2005）。已知S100A8和S100A9具有不同的功能，包括抗微生物活动。在感染过程中，通过募集的嗜中性粒细胞递送至组织脓肿期间。S100A8和S100A9主要存在于S100A8：S100A9异二聚体，其基于其在先天免疫中的作用（Korndorfer IP等人2007）。CalProtectin通过细胞外锰Mn（2+），锌（2+）和可能的铁Fe（2+）螯合来抑制细菌生长，从而限制感染期间的金属离子可用性（Damo Sm等，2013; Brophy MB等。2012,2013;海登Ja等人2013; Gagnon DM等人2015; Nakashige TG等人2015）。CalProtectin表现出广泛的革兰氏阳性和革兰氏阴性细菌病原体的抗菌活性，包括金黄色葡萄球菌，金黄色葡萄球菌，葡萄球菌，粪孢菌粪，颅球菌菌，假霉菌铜绿假单胞菌，大肠杆菌，志贺氏菌和植物植物（Damo Sm等）。2013; kehl-fie te等，2011; nakashige tg等。2015）。S100A8和S100A9都属于S100螺旋转螺旋（EF-HAND）钙CA（2 +）结合蛋白的S100系列。S100蛋白涉及各种蜂窝功能（Donato R等人2013; Zackular JP等，2015; Vogl等人2007）。 Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca(2+) homeostasis, inflammation and migration/invasion (Donato R et al. 2013). During infection, certain S100 proteins can be secreted or released by cells to act as damage-associated molecular patterns (DAMPs) and interact with pattern recognition receptors to modulate inflammatory responses (Foell D et al. 2007; Vogl et al. 2007). In addition, these inflammatory S100 proteins have antimicrobial function by sequestering essential transition metals from bacteria, preventing their growth (Zackular JP et al. 2015). The fundamental structural unit of S100 proteins is a highly integrated antiparallel dimer (Potts BC et al. 1995; Heizmann CW et al. 2002; Brodersen DE et al. 1999; Moroz OV et al. 2009; Gagnon DM et al. 2015). All S100 proteins form this structure as homodimers. S100A8 and S100A9 are unique among all members of the S100 family because they preferentially form a heterodimer. Calprotectin (S100A8:S100A9) and other S100 proteins are Ca(2+)-activated regulators (Brophy MB et al. 2012; Donato R et al. 2013). Inside the cell, where the basal level of Ca(2+) is in the nanomolar range, S100 proteins can serve as a sensor of Ca(2+)-mediated signals. In the extracellular milieu, S100 proteins are perpetually (Ca2+)-bound because Ca(2+) concentration is in the millimolar range. Ca(2+) is also known to stimulate formation of higher order oligomers of S100 proteins, including S100A8/S100A9 tetramers (Leukert N et al. 2006; Korndörfer IP et al. 2007). Upon dimerization S100A8 and S100A9 form two metal binding sites at the dimer interface, both of which can bind to Zn(2+) with high affinity (Kd Zn(2+) about 10e-9 M) (Damo SM et al. 2013; Brophy MB et al. 2013). A chelation of Mn(2+) involves a single binding site (Kd Mn(2+) around 10e-7 - 10e-8 M) (Damo SM et al. 2013; Hayden JA et al. 2013; Gagnon DM et al. 2015). Thus, calprotectin S100A8:S100A9 inhibits bacterial growth by targeting transition metals and sequestering these metals in a process referred to as nutritional immunity.