Table 1.

Immunogenic compounds derived from PGNs and lipids of gut microbes and their mechanisms of actions.

Cell wall-derived compounds	Origin	Mechanisms	Models investigated
iE-DAP	Synthesis	NOD1↑	Macrophages (Chamaillard et al., 2003)
FK-156	Synthesis	IL-1↑	Macrophages (Ahmed and Turk, 1989)
FK-565	Synthesis	NOD1↑	CRC mice (Maisonneuve et al., 2021)
G-MDP-meso-DAP	N. meningitidis	NOD1↑	NF-κB reporter HEK293T cells (Girardin et al., 2003)
Mifamurtide	Synthesis	NOD2↑	Clinical study (Dvorožňáková et al., 2008)
G-MDP	E. faecium	NOD2↑	Pathogen-infected mice (Kim et al., 2019)
G-MDP-Lys	L. salivarius	NOD2↑	IBD mice (Fernandez et al., 2011)
MDP	Synthesis	NOD2↑	Older mice (Gabanyi et al., 2022)
MDP	Synthesis	NOD2↑/IRF4↓	Obese mice (Cavallari et al., 2017)
Intact PGN	Lactobacillus spp.	TLR2↑	Peritoneal macrophages (Shida et al., 2009)
Muropeptides	E. coli	ATP synthase↑	Caenorhabditis elegans (Tian and Han, 2022)
NAG	S. aureus	Hexokinase↑	BMDMs (Wolf et al., 2016)
WTA	L. plantarum	IL-12↑	BMDMs (Kojima et al., 2022)
LTA	L. rhamnosus GG	TLR2↑	Radiation-injury (Riehl et al., 2019)
LTA	L. paracasei D3-5	TLR2↑	Obese mice (Wang et al., 2020b)
LTA	A. kosoi	lgA↑	Murine Peyer’s patch cells (Matsuzaki et al., 2022)
LTA	E. faecalis	PI3K/Akt/mTOR↓	RAW264.7 cell (Lin et al., 2018)
LTA	E. faecalis	p38/ERK1/2↑	BMDMs (Wang et al., 2019)
LPS	E. coli	TLR4↑	IBD mice (Heimesaat et al., 2007)
LPS	P. goldsteinii	TLR4↓	COPD mice (Lai et al., 2022)
LPS	B. vulgatus	MD-2/TLR4↑	IBD mice (Steimle et al., 2019; Di Lorenzo et al., 2020)
PSA	B. fragilis	TLR2/1 and Dectin-1↑	Macrophages (Erturk-Hasdemir et al., 2019)
a15:0-i15:0 PE	A. muciniphila	TLR2/1↑	DCs (Bae et al., 2022)
PG	S. aureus	CD4 + T cell↑	Atopic dermatitis (Monnot et al., 2023)
PE and PC	D. piger	γδ T cells↑	Hypoxia-injury (Li et al., 2022)