Table 2.

The metabolic products of gut microbiota in ARDS.

Literature Number	Types of metabolites	Metabolite name	Role in ARDS
(60, 79, 83), (103–105), (106–108), (109–111), (112–114), (115) (116, 117), (118) (119), (120–123, 106), (124–126), (127) (128, 129)	SCFA Arginine Bile Acid Other metabolites	Butyric Acid Acetic Acid Propionic Acid Arginine Arginine (via L-arginine-modified liposomes) Arginine (synthesized from Glutamine) Cholic acid, chenodeoxycholic acid Deoxycholic acid, Lithocholic acid, Ursodeoxycholic acid Succinic Acid Indole Derivatives Nicotinic acid Choline Metabolites	Reduces ARDS severity, decreases inflammation, promotes M2 macrophage polarization, improves gut and mucosal barrier function, and regulates immune responses. Uncertain role in ARDS, possibly affects inflammation in specific mouse models. Inhibits activation of NLRP3 inflammasomes, modulates Keap1/Nrf2 pathway, inhibits NF-κB axis activation. Improves inflammatory conditions. Direct correlation with MDSCs expansion in COVID-19, mitigates immune suppression, reduces duration of mechanical ventilation, decreases mortality rates. Used in curcumin treatment to target pulmonary M1 macrophages, modulates immunological responses in ALI/ARDS. Improve clinical outcomes in respiratory illnesses, therapeutic potential in ARDS treatment. Elevated levels of bile acids and involved in regulating bile acid metabolism. Produced by Clostridium with 7α-dehydroxylating capabilities, play a role in maintaining gastrointestinal microbiome homeostasis. Protect against pulmonary injury. Linked to protein succinylation, activation of SUCNR1, eliciting pro-inflammatory responses, potential therapeutic target in ischemia-reperfusion injuries. Regulatory influence on microbial behavior, host-pathogen interactions, enhances host epithelial barrier integrity, potential roles in ARDS. Agonist for GPR109A, suppresses NF-κB, anti-inflammatory and immunomodulatory properties, influence in ARDS still lacks evidence. Found in pulmonary surfactants, mitigates inflammation, anti-inflammatory properties, distinct metabolic profiles in influenza and COVID-19-induced ARDS.