Download 4-Microbiota Part

Basic Bacteriology
Part-4
Microbiota
(Normal Flora)
Second Semester 2016-2017
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The symbiotic relationship between humans and their microbiota can be considered as mutualism and
commensalism. However, some members of human microbiota can be opportunistic pathogens.
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Inflammatory bowel diseases (IBDs) reflect the cooperative influence of numerous host and
environmental factors, including those of elements of the intestinal immune system, the gut microbiota,
and dietary habits. This review focuses on features of the gut microbiota and mucosal immune system
that are important in the development and control of IBDs.
Gut innate-type immune cells, including dendritic cells, innate lymphoid cells, and mast cells,
educate acquired-type immune cells and intestinal epithelial cells to achieve a symbiotic relationship
with commensal bacteria. However, perturbation of the number or type of commensal microorganisms
and endogenous genetic polymorphisms that affect immune responses and epithelial barrier system can
ultimately lead to IBDs.
Providing beneficial bacteria or fecal microbiota transplants helps to reestablish the intestinal
environment, maintain its homeostasis, and ameliorate IBDs.
The gut immune system participates in a symbiotic milieu that includes cohabiting commensal bacteria.
However, dysbiotic conditions and aberrations in the epithelial barrier and gut immune system can
disrupt the mutualistic relationship between the host and gut microbiota, leading to IBDs. Progress in
our molecular and cellular understanding of this relationship has yielded numerous insights regarding
clinical applications for the treatment of IBDs.
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HORMONES 2015, 14(3):358-369
Beyond gut microbiota: understanding obesity and type 2 diabetes
Obesity and type 2 diabetes are metabolic diseases that have reached epidemic proportions
worldwide. Although their etiology is complex, both result from interplay between behavior,
environment and genetic factors. Within ambient determinants, human overall gut bacteria have
been identified as a crucial mediator of obesity and its consequences.
Gut microbiota plays a crucial role in gastro-intestinal mucosa permeability and regulates the
fermentation and absorption of dietary polysaccharides, which may explain its importance in
the regulation of fat accumulation and the resultant development of obesity-related diseases.
The main objective of this review is to address the pathogenic association between gut
microbiota and obesity and to explore related innovative therapeutic targets. New insights into
the role of the small bowel and gut microbiota in diabetes and obesity may make possible the
development of integrated strategies to prevent and treat these metabolic disorders.
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