🦠 Probiotic Immune Modulation Mechanism Simulator

Gut Lumen Colonization Near GALT

Probiotic strains establish near gut-associated lymphoid tissue.

• ~38 T: Gut bacterial cells (roughly matches human cell count)
• ~200: Peyer's patches (ileum) (lymphoid follicle clusters)
• 2: Common probiotic genera (Lactobacillus, Bifidobacterium)
• ~150 µm: Mucus layer thickness (inner layer, bacteria-free)

Lumen niche establishment

Probiotics adhere to mucus near follicle-associated epithelium.

Competitive exclusion

Colonizers crowd out pathogens for lumen space and nutrients.

Dose-dependent density

Higher probiotic dose raises steady-state lumen population.

Sustained dosing over weeks stabilizes colonization density.

Pattern Recognition in Peyer's Patches

Dendritic cells sample microbial molecules through M cells.

• ~10%: M cell coverage (of follicle-associated epithelium)
• TLR 1-9: Key receptor family (toll-like pattern receptors)
• <1 hr: Sampling delay (antigen uptake to DC contact)
• 3: MAMP examples (peptidoglycan, LTA, exopolysaccharide)

M cell transcytosis

M cells shuttle luminal antigens across the epithelium.

Dendritic cell dendrites

DCs extend processes to sample lumen contents directly.

Receptor binding

Surface pattern receptors bind conserved microbial motifs.

Strain-specific surface molecules shape the recognition signal.

Dendritic Cell to T-Cell Signaling

Activated dendritic cells present antigen to naive T-cells.

• ~24 hr: DC migration time (patch to draining lymph node)
• Peptide: MHC-II presentation (antigen fragment display)
• CD80/86: Costimulatory signal (second activation signal)
• Interfollicular: T-cell zone (Peyer's patch region)

Antigen presentation

DCs display processed peptides on MHC-II molecules.

T-cell priming

Naive T-cells engage DCs and receive activation signals.

Regulatory skewing

Probiotic signals bias differentiation toward Treg lineage.

Signal strength and duration steer T-cell fate decisions.

Cytokine Balance Modulation

Signaling cascades shift cytokines toward a regulatory profile.

• IL-10: Key regulatory cytokine (anti-inflammatory signal)
• TNF-α: Key pro-inflam. cytokine (inflammatory driver)
• Treg induction: TGF-β role (supports differentiation)
• ~1-2 wk: Shift onset (with sustained dosing)

Regulatory cytokine rise

IL-10 and TGF-β output increases with Treg signaling.

Pro-inflammatory decline

TNF-α and IL-6 output falls as balance shifts.

Dose and duration coupling

Both sliders jointly drive the cytokine balance rate.

Longer exposure compounds the dose-driven cytokine shift.

Immune Homeostasis in the Gut

A modulated response settles into stable, balanced immunity.

• >80: Balance score target (homeostasis threshold)
• Sustained: Treg population effect (elevated regulatory presence)
• Tighter junctions: Barrier benefit (reduced permeability)
• IBD, allergy: Clinical relevance (modulation target conditions)

Stable regulatory tone

Treg and cytokine levels settle at a balanced set point.

Reduced inflammatory tone

Pro-inflammatory signaling stays persistently suppressed.

Maintenance requirement

Continued exposure sustains the homeostatic balance.

Homeostasis is dynamic — it depends on ongoing colonization.