Table 1.

Summary table of studies focusing on the association between microbiota composition and inflammation/obesity.

Main Outcome	Type of Study	Main Findings
Microbiota composition	Studies in mice	-Increased Bacteroidetes abundance in lean mice [16] -Bacteria with increased energy-harvesting activity [20,21]
	Human studies	-Reduced diversity in overweight and obese individuals is associated with high hs-CRP levels [17] -Increased Firmicutes abundance in overweight and obese individuals [17,18,19] -Increased abundance of pro-inflammatory bacteria (e.g., Escherichia coli) while reduced bacteria with anti-inflammatory properties (e.g., Fecalibacterium prausnitzii) [22,23]
Microbial metabolites	In vitro studies	-Butyrate reduces LPS concentration and activation of macrophages [33]
	Studies in mice	-Lactobacillus increase the production of GABA, reducing food intake [27] -LPS infusion increases TNF-α levels [29]
	Human studies	-LPS concentration is associated with obesity, MS, and T2D [30,31,32,33] -Weight loss (bariatric surgery) decrease LPS concentrations [34,35]
Intestinal permeability	Studies in mice	-Butyrate increase the expression of mucin and tight junction proteins [43] -Akkermansia in lean mice increase thigh junction function [46]
	Human studies	-Faecalibacteria abundance is associated with reduced zonulin levels in overweight women [45]
Gut microbiota and inflammasome/cytokines interplay	Studies in mice	-Dysbiosis increases inflammation and obesity [63] -Prevotella abundance reduces inflammation [64,65]

GABA—γ-aminobutyric acid; hs-CRP—high sensitivity C-reactive protein; LPS—lipopolysaccharide; MS—metabolic syndrome; T2D—type 2 diabetes.