Intestinal reengineering: Scientific advances in intestinal transplantation

Table 2 The immune characteristics of intestinal specific microbiota and their correlation with small intestine transplantation

Bacterial genus	Specific species	Immune mechanism	Receptor/pathway	Association with intestinal transplantation	Potential applications/risks	Ref.
Bifidobacterium	B. longum	Promotes mucosal immune maturation, enhances epithelial integrity	TLR2/4	Loss post-transplant linked to GVHD predisposition	Probiotic supplementation may mitigate GVHD risk	[234,235]
	B. infantis	Balances Th1/Th2 response, modulates cytokine milieu	GPR43 (SCFA-mediated)	Suppresses systemic inflammation, fosters tolerance	May enhance immunosuppressive efficacy	[236]
Lactobacillus	L. plantarum	Downregulates pro-inflammatory cytokines (IL-6, IL-8)	TLR2	Limits endotoxemia and systemic inflammation	Helps prevent post-transplant sepsis	[237]
	L. reuteri	Promotes IL-10 production and Treg induction	AhR	Enhances barrier repair, reduces mucosal inflammation	Therapeutic for immune enteropathies	[238]
Bacteroides	B. fragilis	Induces Treg via PSA antigen	TLR2	Shown to promote tolerance in transplant models	Potential microbial immunotherapy target	[239]
	B. thetaiotaomicron	Promotes IgA secretion, modulates dendritic cell response	TLR4	Supports mucosal immunity, limits pathogen overgrowth	May prevent Enterobacteriaceae dominance	[240,241]
Escherichia coli	Commensal E. coli	Activates basal innate immunity	TLR5/MyD88	Maintains immune tone, but overgrowth risks rejection	Surveillance for strain virulence needed	[242]
	Pathogenic E. coli (e.g., EHEC)	Secretes shiga-like toxins, induces strong cytokine storm	GB3 receptor	Triggers mucosal necrosis, worsens ischemia-reperfusion injury	Requires antibiotic prophylaxis	[243]
Clostridium	C. perfringens	Produces α-toxin, damages tight junctions	-	Can cause graft necrosis, sepsis	Early diagnosis critical	[244]
	C. difficile	Induces pseudomembranous colitis via toxin A/B		Common post-transplant pathogen	Fecal microbiota transplantation emerging as a salvage therapy	[245]
Fusobacterium	F. nucleatum	Activates NF-κB, enhances IL-6/IL-8 release	TLR2/4	Linked to chronic inflammation and neoplasia	Considered a pro-inflammatory marker	[246,247]
Enterococcus	E. faecalis	Inhibits inflammasome, alters antimicrobial peptide balance		Contributes to barrier disruption and bacteremia	Targeted decolonization recommended	[248]
Prevotella	P. copri	Modulates Th17 response		Implicated in dysregulated immunity post- intestinal transplantation	Microbiome-guided regulation needed	[249]
Akkermansia	A. muciniphila	Enhances mucus production, improves tight junctions	GPR43	Shown to improve gut permeability and glucose homeostasis	Probiotic candidate under investigation	[250]
Roseburia	Roseburia spp.	Butyrate production, anti-inflammatory effect	FFAR3 (GPR41)	Maintains Treg differentiation and epithelial repair	Supports mucosal tolerance post-transplant	[251]
Sutterella	Sutterella spp.	Alters IgA response and epithelial interaction		Poorly understood but potentially modulates rejection	Requires further research	[252]

B. longum: Bifidobacterium longum; B. infantis: Bifidobacterium infantis; L. plantarum: Lactiplantibacillus plantarum; L. reuteri: Limosilactobacillus reuteri; B. fragilis: Bacteroides fragilis; B. thetaiotaomicron: Bacteroides thetaiotaomicron; E. coli: Escherichia coli; C. perfringens: Clostridium perfringens; C. difficile: Clostridioides difficile; F. nucleatum: Fusobacterium nucleatum; E. faecalis: Enterococcus faecalis; P. copri: Prevotella copri; A. muciniphila: Akkermansia muciniphila; EHEC: Enterohemorrhagic Escherichia coli; GVHD: Graft-vs-host disease; IL-1: Interleukin-1; SCFA: Short-chain fatty acid; Treg: Regulatory T cell; PSA: Prostate-specific antigen; TLR: Toll-like receptor; NF-κB: Nuclear factor kappa-B.