Aspects of Gut Microbiota and Immune System Interactions in Infectious Diseases, Immunopathology, and Cancer (original) (raw)

The immune system and the gut microbiota: friends or foes?

Nature Reviews Immunology, 2010

The mammalian intestine is home to a complex community of trillions of bacteria that are engaged in a dynamic interaction with the host immune system. Determining the principles that govern host-microbiota relationships is the focus of intense research. Here, we describe how the intestinal microbiota is able to influence the balance between pro-inflammatory and regulatory responses and shape the host's immune system. We suggest that improving our understanding of the intestinal microbiota has therapeutic implications, not only for intestinal immunopathologies but also for systemic immune diseases.

Gut Microbiota and Immune System Interactions

Microorganisms

Dynamic interactions between gut microbiota and a host’s innate and adaptive immune systems are essential in maintaining intestinal homeostasis and inhibiting inflammation. Gut microbiota metabolizes proteins and complex carbohydrates, synthesizes vitamins, and produces an enormous number of metabolic products that can mediate cross-talk between gut epithelium and immune cells. As a defense mechanism, gut epithelial cells produce a mucosal barrier to segregate microbiota from host immune cells and reduce intestinal permeability. An impaired interaction between gut bacteria and the mucosal immune system can lead to an increased abundance of potentially pathogenic gram-negative bacteria and their associated metabolic changes, disrupting the epithelial barrier and increasing susceptibility to infections. Gut dysbiosis, or negative alterations in gut microbial composition, can also dysregulate immune responses, causing inflammation, oxidative stress, and insulin resistance. Over time, c...

Gut Microbiota, Dysbiosis and Immune System; A Brief Review

2019

The gut Microbiota is the large population of microorganisms residing in the human gastrointestinal tract. The gut Microbiota constantly interacts with the various host organs and systems. While there are many protective functions due to the gut Microbiota, changes in the composition and function of the Microbiota, which is defined as dysbiosis, has been shown in several diseased conditions. The gut Microbiota affect the immune system. While normal gut Microbiota are essential for existence of a normal immune system, dysbiosis can result in deviation of immune responses. In this article, we will talked the effects of the gut Microbiota on different elements of immune system.

Gut Microbiome Composition as the Key Factor for Immunomodulation in the Host

Microbiome-Gut-Brain Axis, 2022

Gut microbiota is an intricate assortment of microbes that naturally thrive in the digestive tract of humans and other animals. These microbes are very critical for host development, immunity and nutrition. Ample scientific evidences establish the role of gut microbes in human health and diseases. Especially with respect to host immunity, the interaction is highly interlinked with microbiota influencing the induction, training and function of host immune cells, thereby regulating immune homeostasis. In turn, the immune system has a central role in shaping composition, diversity and distribution of host gut microbiota. When immune system–microbiota alliance is operating optimally, a myriad of health benefits are rendered to the host including protection against pathogens, intact intestinal barrier integrity, immunohomeostasis and others. Any disturbance in this intricate association is strongly associated with immunological dysregulation with aberrant immune responses that result in inflammation and tissue injury and subsequently can cause autoimmunity, allergy and cancer. This clearly reflects interdependence of host immune system and their gut microbiota as well the critical role of immune system–microbiota cross talk in the host health and disease.

The mutual interplay of gut microbiota, diet and human disease

The FEBS Journal, 2020

The intestinal milieu harbours the gut microbiota, consisting of a complex community of bacteria, archaea, fungi, viruses and protozoans that bring to the host organism an endowment of cells and genes more numerous than its own. In the last 10 years, mounting evidence has highlighted the prominent influence of the gut mutualistic bacterial communities on human health. Microbial colonization occurs alongside with immune system development and plays a role in intestinal physiology. The community of the gut microbiota does not undergo significant fluctuations throughout adult life. However, bacterial infections, antibiotic treatment, lifestyle, surgery and diet might profoundly affect it. Gut microbiota dysbiosis, defined as marked alterations in the amount and function of the intestinal microorganisms, is correlated with the aetiology of chronic noncommunicable diseases, ranging from cardiovascular, neurologic, respiratory and metabolic illnesses to cancer. In this review, we focus on...

Immune homeostasis, dysbiosis and therapeutic modulation of the gut microbiota

The distal gut harbours ∼10 13 bacteria, representing the most densely populated ecosystem known. The functional diversity expressed by these communities is enormous and relatively unexplored. The past decade of research has unveiled the profound influence that the resident microbial populations bestow to host immunity and metabolism. The evolution of these communities from birth generates a highly adapted and highly personalized microbiota that is stable in healthy individuals. Immune homeostasis is achieved and maintained due in part to the extensive interplay between the gut microbiota and host mucosal immune system. Imbalances of gut microbiota may lead to a number of pathologies such as obesity, type I and type II diabetes, inflammatory bowel disease (IBD), colorectal cancer (CRC) and inflammaging/immunosenscence in the elderly. In-depth understanding of the underlying mechanisms that control homeostasis and dysbiosis of the gut microbiota represents an important step in our ability to reliably modulate the gut microbiota with positive clinical outcomes. The potential of microbiome-based therapeutics to treat epidemic human disease is of great interest. New therapeutic paradigms, including second-generation personalized probiotics, prebiotics, narrow spectrum antibiotic treatment and faecal microbiome transplantation, may provide safer and natural alternatives to traditional clinical interventions for chronic diseases. This review discusses host–microbiota homeostasis, consequences of its perturbation and the associated challenges in therapeutic developments that lie ahead.

Current Knowledge on Intestinal Microbes and Immunity

Science Insights, 2018

The aggregation of many microorganisms, ranging from virus, bacteria, parasites, to lower plants such as fungi are frequently referred to as the microbiota, colonizes the skin and mucosal surfaces of vertebrates. In man, more than 100 trillion microorganisms, mostly bacteria, colonize the oral-gastrointestinal tract, and the majority of these microbes dwell in the distal digestive tract. A large number of years of co-evolution between the host and microorganisms have prompted a mutualistic relationship in which the micro-biota adds to many host physiological processes and, thus, the host gives niches and supplements to microbial survival. The principal roles of the microbiota to the host incorporate the digestion and fermentation of sugars, the synthesis of vitamins, the improvement of gut-related lymphoid tissues (GALTs), the polarization of gut-specific insusceptible reactions and the aversion of colonization by pathogens. Thus, gut resistant reactions that are initiated by commensal populaces control the creation of the mi-crobiota. Therefore, an overwhelming interchange between the host immune system and the microbiota is fundamental for gut homeostasis. Nevertheless, when the mutualistic relationship between the host and microbiota is disturbed, the gut microbiota can initiate or add to infection. In this review, we will be discussing on both the beneficial and detrimental roles of the gut microbiota.■