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Microbes & Immunity Management of obesity

Changes in gut microbiome
Factor affecting gut microbiota

Chronic stress Modulates the
SCFA production hormones liptin,
peptide YY,
and GLP-1
Poor diet

Antibiotics Alter FXR &
Bile acids Adiposity;
TGR5 activation
dyslipidemia
Sleep disorder
Poor diet
↓Microbial diversity
& richness Metabolic Elevated serum
↓Microbial gene count endotoximia levels of LPS
Genetics ↓Oscillospira,
Rikenellaceae
↓ Bifidobacterium,
Early stages
Akkermasia
↑Rosebiria
↑Prevotellaceae,
Alcaligenaceae,
Erysipelotrichaceae
Figure 3. Factors altering gut microbiome leading to obesity
Abbreviations: FXR: Farnesoid X receptors; LPS: Lipopolysaccharide; SCFA: Short-chain fatty acid; TGR5: Takeda G-protein-coupled receptor 5c.
Table 1. Microbial taxa in obese individuals with metabolic disorders

Metabolic disorders Risk‑enhancing Bacteria Protective or risk‑lowering bacteria
Metabolic syndrome Coriobacteriaceae Faecalibacterium prausnitzii, Parabacteroides, Bacteroides caccae,
Parabacteroides distasonis, and Oscillospira
Impaired glucose Bacteroides ovatus and Enterobacteriaceae Coprococcus, Haemophilus parainfluenzae, Parabacteroides,
tolerance or insulin Prevotellaceae and Veillonella Bacteroides caccae
resistance Oscillibacter sp., Agathobaculum butyriciproducens, Haemophilus
parainfluenzae, Veillonella parvula, Dialister invisus
High diastolic blood Clostridium and Clostridiaceae -
pressure
Low HDL cholesterol Lachnospiraceae, Gemellaceae, and -
Turicibacter
Cardiovascular disorders Prevotellaceae and Veillonella Coriobacteriaceae

negative bacteria. 66-68 The proliferation of Gram-negative through lymphatic fluid. These pathways lead to increased
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bacteria in obese individuals, such as Veillonella, can LPS levels in circulation. LPS can trigger immunological
result in an increased concentration of LPS in the colon. reactions in adipose tissue and the liver during systemic
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The increase of LPS can compromise the gut barrier by circulation. LPS initially associates with the LPS-binding
stimulating the TLR4/MyD88/IRAK4 signaling pathway protein and then forms a complex with cluster of
in intestinal epithelial cells, subsequently leading to differentiation 14. This complex subsequently stimulates
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the transfer of LPS from the intestine into the systemic the NF-κB and activator protein 1 by activating TLR4 present
circulation. Furthermore, the reduction of A. muciniphila on macrophages and adipose tissue, thereby facilitating
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facilitates the transfer of microbial by-products due to its the production of pro-inflammatory chemokines and
role in preserving gut barrier integrity. Moreover, a high- cytokines, including MCP-1, TNF-α, and IL-6. 43,73 These
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fat diet facilitates the integration of LPS into chylomicrons, cytokines can influence adipocytes, prompting them to
thereby enhancing the absorption of LPS in the intestine release more cytokines and chemokines through paracrine
and its subsequent transfer to the systemic circulation and autocrine mechanisms. Furthermore, overexpression
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Volume 2 Issue 4 (2025) 50 doi: 10.36922/MI025160036