Table 2.

Mechanisms of action of B. clausii probiotics identified through preclinical studies.

Mechanism of Action	Tested Strain	Host Environment	Effect of Probiotic	Reference
Enhancing gut immune function	B. clausii (O/C, N/R, SIN, and T) live cells	Caco-2 cell line	Production of antimicrobial peptides, mucin, and tight junction proteins; increase of cell proliferation; release of pro-inflammatory cytokines	[48]
	B. clausii (O/C, N/R, SIN, and T) live cells	Duodenal cells of esophagitis patients	Modulation of gene expression related to immunity, cell growth and death, cell signaling, and cell adhesion	[49]
	B. clausii as part of gut community in fecal microbiota transfer	Mice with pancreatic cancer	Alteration of tumor microbiome composition, tumor growth, and immune infiltration	[50]
	B. clausii SC-109 spores as part of a synbiotic formulation	Simulator of Human Intestinal Microbial Ecosystem (SHIME®)	Increased production of butyrate, alteration of gut microbiota	[51]
	B. clausii UBBC07 spores	Rat model of uremia	Reduction of acetaminophen-induced nephrotoxicity	[52]
Antimicrobial and immunomodulatory activity	B. clausii Sinuberase® live cells	In vitro fermentation	Production of antimicrobial peptides	[53]
	B. clausii UBBC07 live cells	SHIME®	Production of the lantibiotic clausin	[47]
	B. clausii O/C	In vitro culture medium	Production of the lantibiotic clausin	[54]
	Live cells of B. clausii isolate #KCTC 10,277 BP from tidal mudflats of the Korean Yellow Sea	Mouse model of allergic asthma	Reduction of inflammation	[55]
	B. clausii MTCC-8326 live cells	RAW264.7 murine macrophage cell line	Balance expression of pro- and anti-inflammatory cytokines, protection from S. typhimurium infections and related toxicity	[56,57]
	B. clausii O/C live cells	Caco-2 cell line	Protection from cytotoxic effects of Clostridium difficile and Bacillus cereus	[58]
	B. clausii (O/C, N/R, SIN, and T) live cells	Swiss murine peritoneal cells	Increased expression of pro-inflammatory cytokines and stimulation of nitrite production and proliferation of CD4+ T cells	[59]
	B. clausii O/C live cells	RAW 264.7 murine macrophage cell line	Induction of nitric oxide production	[60]
	B. clausii (O/C, N/R, SIN, and T) spores	Mouse model of ulcerative colitis	Slight improvement in symptoms of mild colitis	[61]
	B. clausii (O/C, N/R, SIN, and T) spores	Mouse model of schistosomiasis	Reduction of parasitic load and egg load, reduction of inflammation	[62]
	B. clausii (O/C, N/R, SIN, and T) spores	Mice with enteropathogenic E. coli infection	Reduction in intestinal lesions, debris and immune cell infiltration, increase in mucus-secreting goblet cells	[63]