Page 32 - JCBP-3-3

Journal of Clinical and
Basic Psychosomatics Microbiota in psychosomatic disorders

connections to the CNS through sensory and motor 2. The gut microbiota and its role in health
pathways. 1-4 and disease
The hypothalamic-pituitary-adrenal (HPA) axis, which The human gut microbiota, a complex community of
governs the body’s stress response, is also influenced by trillions of microorganisms, plays a vital role in digestion,
gut-derived signals. Stress hormones such as cortisol can metabolism, immune modulation, and CNS influence.
impact gut function and alter microbial composition, A diverse microbiota is crucial for maintaining health,
further linking the gut to systemic stress responses. and its composition is shaped by genetics, diet, age,
5,6
Overactivation of the HPA axis leads to excessive cortisol and environment (Figure 1). A healthy and diverse gut
release, gut dysbiosis, and systemic inflammation. This microbiota prevents infections and supports immune
disruption weakens the gut barrier, allowing inflammatory defenses. 14,15
molecules to enter circulation, affecting neurotransmitter
production and neuroinflammation. These physiological Gut dysbiosis is characterized by distinct microbial
changes create a feedback loop where psychological distress imbalances that vary across different diseases,
worsens gut health, further amplifying psychosomatic influencing host metabolism, immunity, and overall
symptoms. 7-9 health. 16,17 In inflammatory bowel disease (IBD), there
is a marked reduction in anti-inflammatory bacteria
The trillions of microorganisms comprising the gut such as Faecalibacterium prausnitzii, Roseburia, and
microbiota produce metabolites, neurotransmitters, and Akkermansia muciniphila (Table 1), accompanied by
inflammatory mediators that directly influence brain function an overgrowth of pro-inflammatory species, such as
(Figure 1). In addition, the microbiota also affects critical Escherichia coli, Enterobacteriaceae, Fusobacterium,
10
processes such as neurogenesis, the integrity of the blood– and Ruminococcus gnavus, leading to increased gut
brain barrier (BBB), and neural inflammation, underscoring permeability and chronic immune activation. 18,19
their impact on mental and emotional health. 11-13 Similarly, in irritable bowel syndrome (IBS), a decline
Given the increasing prevalence of psychosomatic in Bifidobacterium, Lactobacillus, and F. prausnitzii is
disorders and GI dysfunctions, understanding microbial observed, alongside an increase in Methanobrevibacter
contributions to these conditions is essential. This review smithii, E. coli, Clostridium species, and Proteobacteria,
analyzes gut microbiota research and its impact on contributing to visceral hypersensitivity, altered
psychosomatic conditions, identifying knowledge gaps motility, and bloating. 20,21 In obesity and metabolic
and discussing recent therapeutic strategies. syndrome, dysbiosis is marked by an increased
Firmicutes-to-Bacteroidetes ratio, with elevated levels
of Ruminococcus and Clostridium species that enhance
calorie absorption, while beneficial microbes such as
A. muciniphila, Bifidobacterium, and Roseburia are
diminished, promoting systemic inflammation and
insulin resistance 22,23 (Table 1). Type 2 diabetes presents
with a similar loss of butyrate-producing bacteria, such
as F. prausnitzii and Roseburia, coupled with an increase
in E. coli, Ruminococcus, and Proteobacteria, which
contribute to endotoxemia, metabolic dysfunction,
and chronic inflammation. In colorectal cancer,
dysbiosis favors tumor-promoting bacteria such as
Fusobacterium nucleatum, E. coli, Bacteroides fragilis, and
Peptostreptococcus, which generate pro-inflammatory
Figure 1. Role of gut microbiota in producing key metabolites and and genotoxic compounds, while protective short-
their absorption by intestinal cells. The image illustrates the interaction chain fatty acids (SCFA)-producing microbes, such
between the gut microbiota and the intestinal epithelium. The microbiota as Butyricicoccus and Lachnospiraceae are depleted,
metabolizes dietary components to produce essential metabolites such as facilitating tumorigenesis. 24,25
short-chain fatty acids (SCFAs), vitamins, neurotransmitters, and various
breakdown products. These metabolites are subsequently absorbed by In autoimmune diseases, including rheumatoid
intestinal epithelial cells and enter systemic circulation, impacting host arthritis, multiple sclerosis, and lupus, dysbiosis is
physiology and health. SCFAs (yellow), vitamins (red), neurotransmitters characterized by a loss of SCFA-producing bacteria, such
(blue), and breakdown products (gray) are shown as being generated by
diverse microbial species within the gut lumen and transported across the as F. prausnitzii and A. muciniphila (Table 1), along with
intestinal barrier. Image created using BioRender. an overrepresentation of Prevotella copri in rheumatoid

Volume 3 Issue 3 (2025) 26 doi: 10.36922/JCBP025040008