Microbiota in health and irritable bowel syndrome: current knowledge, perspectives and therapeutic options

Abstract

The gastrointestinal tract is a natural reservoir of microbiota. The gut is germ-free at birth, but rapidly becomes host to various bacteria establishing a progressively mutual relationship. The composition of gut microbiota is individual-specific and depends on the genotype of the host and environmental factors. Novel techniques have been used to characterize gastrointestinal microbiota, including genomic approaches. The bacterial profile shows that dominant and minor phyla are present in the gastrointestinal tract. From the proximal to the distal segments of the gut the bacterial density gradually increases, reaching an estimated 10¹¹ to 10¹² bacteria per gram of colonic content. Dynamic interactions between gut and microbiota play a physiological role in metabolic, protective and structural functions, while dysbiosis contributes to several diseases. Microbiota appear to play a role in IBS, where qualitative and quantitative changes of bacteriaoccur in IBS subtypes. Initial therapeutic approaches in IBS have focused on microbiota. The relationship between perturbations of the microbiota, mucosal inflammation and IBS remains to be further investigated.

Key Words::

• antibiotic
• gastrointestinal tract
• irritable bowel syndrome
• microbiota
• prebiotic
• probiotic
• synbiotic

Acknowledgements

This work was supported in part by research grants from the Italian National Research Council (CNR) (short-term mobility grant 2005), the University of Bari (grants ORBA09XZZT, ORBA08YHKX) (P.P.), University of Bari (DR11598-2009) and Fondazione Cassa di Risparmio di Puglia (Research grant 2012). We are indebted to Paola De Benedictis, Rosa De Venuto, Michele Persichella and Valentina Ruggiero for their skilful technical assistance. We dedicate this paper to the memory of Francesco Vitiello, Professor of Physiology at the University of Bari Medical School. We are indebted to Prof. JT Lamont (Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA) for stimulating scientific discussion and kindly revising the paper.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.