Colonocyte bioenergetics
The metabolic state of the colon's epithelial cells — particularly their capacity to oxidise butyrate via mitochondrial β-oxidation.
Colonocytes consume oxygen aggressively when bioenergetically intact, holding the lumen near-anaerobic. When iron-sulfur cluster assembly, NAD⁺/SIRT3 signalling, or mitochondrial throughput drop, oxygen leaks into the lumen and downstream changes follow.
Oxygen-gradient instability
The steep epithelial-to-lumen oxygen gradient that gates microbial ecology.
When colonocyte oxygen consumption falls, lumen pO₂ rises and facultative anaerobes (Proteobacteria, Enterobacteriaceae) gain a thermodynamic edge over obligate anaerobes (Firmicutes butyrate producers).
Microbial habitat shift
Re-organisation of community composition and function in response to a changed host environment.
Habitat-driven dysbiosis: communities reassemble around the new oxygen, pH, mucus, and motility regime. The ecology is downstream of host state, not the originating event.
Endotoxin / metabolite stress
The output of a destabilised community: LPS, abnormal SCFA ratios, hydrogen sulfide, methane, ethanol, biogenic amines.
Metabolite stress acts both locally (epithelial irritation, motility effects) and systemically (immune priming, hepatic load, vascular signalling).
Gut barrier strain
Loss of selective epithelial permeability and mucus integrity.
Tight-junction remodelling, mucus thinning, and reduced antimicrobial peptide output let microbial products reach the lamina propria and portal circulation.
Immune & mast-cell activation
Local and systemic immune signalling, including mast-cell mediator release at threshold-crossing intensity.
Persistent low-grade microbial signalling primes Th-skewed responses and lowers the mast-cell activation threshold, producing the symptom volatility characteristic of MCAS-overlap presentations.
Mitochondrial reserve
Whole-organism bioenergetic headroom — the buffer that absorbs metabolic stress before symptoms appear.
Reduced mitochondrial reserve lowers the threshold at which inflammation, hypoxia, or microbial signalling translate into systemic symptoms — a host-side feedback loop with the colonocyte layer.
Motility instability
Altered migrating motor complex and segmental contraction patterns from neuro-immune perturbation.
Mast-cell mediators and microbial metabolites perturb the enteric nervous system, producing both stasis and accelerated transit phenotypes that re-feed the habitat shift.
Systemic symptoms
The clinical surface — fatigue, post-prandial malaise, food reactivity, neurocognitive symptoms, autonomic instability.
These present as discrete diagnoses (SIBO, MCAS, long COVID, IBS) but in complex cases share an upstream substrate: a host that cannot maintain the conditions of a stable epithelial-microbial interface.