Molecular signalling during cross talk between gut brain axis regulation and progression of irritable bowel syndrome: A comprehensive review

Table 2 Various therapies prescribed for the treatment of irritable bowel syndrome along with their possible mode of action

Therapy	Description	Proposed mechanism(s) of action
Prebiotics	Ingested compounds targeted to stimulate gut microbiota	Mechanism of action undefined, but may include: Anti-inflammatory effects; inhibition of pathogen adherence; and growth of intestinal mucosal layer
Probiotics	Ingested microorganisms (e.g., bacteria)	Mechanism of action undefined, but may include: Inhibition of pathogenic microorganism colonization; support intestinal barrier integrity and function; production of beneficial micronutrients; and activation and augmentation of the enteric nervous system
Rifaximin	Nonabsorbable, bile-soluble antibiotic indicated for the treatment of adults with IBS-D	Antibacterial against Gram-positive and Gram-negative bacteria: Modulation of gut-immune signalling; inhibition of bacterial translocation; SIBO eradication (in some patients); causing decreases in GI methane concentrations in combination; and with the antibiotic neomycin (in patients with IBS-C)
SBI	Prescription medical food for patients with IBS-D	Modulation of gut microbiota: Causing decreases in GI permeability
SYN-010	Derivative of the HMG-CoA reductase inhibitor lovastatin lactone; currently in development for the treatment of patients with IBS-C	Inhibition of methane production by Methanobrevibacter smithii
Dietary modification	Variable; one example is the low FODMAP diet	Causing decreases in GI gas production
		Causing decreases in intra-luminal fluid production

FODMAP: Fermentable oligo-, di-, monosaccharides and polyols; GI: Gastrointestinal; HMG-CoA: 3-hydroxy-3-methylglutaryl-coenzyme A; IBS-C: Constipation-predominant irritable bowel syndrome; IBS-D: Diarrhea-predominant irritable bowel syndrome; SBI: Serum-derived bovine immunoglobulin; SIBO: Small intestinal bacterial overgrowth.