Human Microbiome and its Association With Health and Diseases

Human microbiota are distinct communities of microorganisms that resides at different body niches. Exploration of the human microbiome has become a reality due to the availability of powerful metagenomics and metatranscriptomic analysis technologies. Recent advances in sequencing and bioinformatics over the past decade help provide a deep insight into the nature of the host-microbial interactions and identification of potential deriver genes and pathways associated with human health, well-being, and predisposition to different diseases. In the present review, we outline recent studies devoted to elucidate the possible link between the microbiota and various type of diseases. The present review also highlights the potential utilization of microbiota as a potential therapeutic option to treat a wide array of human diseases.

Humans are viewed as composites of human and microbial cells. Human microbiota are complex and dynamic microbial communities composed mainly of bacteria, but also includes protozoa, archaea, viruses, and fungi that resides in and on different body niches such as oral cavity, throat, esophagus, stomach, colon, urogenital tract, respiratory tract, and skin. The number of microbial cells inhabiting human body is estimated to exceed the H.sapiens cells by 10-fold and estimated at 350 trillion microbial cells.

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Microbiome-host interactions. Schematic representation showing the perplexed microbial-host
interactions due to different triggering factors on microbiota and their genetic material constitute;
the human microbiome.

Source: Wiley

Association Between Genetic Variation And Influenza Severity.

It is estimated that in the USA influenza -related deaths in recent years have ranged from 12,000 to 56,000. Factors like age, obesity, pregnancy and such chronic health conditions as asthma, chronic lung disease and heart disease are associated with an elevated risk of complications and death.

However, there are no proven genetic markers of influenza risk with an established mechanism of action. Interferon Induced Transmembrane Protein 3 (IFITM3) is an anti-viral protein that helps to block influenza infection of lung cells and to promote survival of the killer T cells that help clear the infection in the airways.

Image: A scanning electron micrograph of a CD8+ T cell engaging a virus.

(Photo courtesy of Dennis Kunkel).

A group of scientists collaborating with those at St. Jude Children's Research Hospital (Memphis, TN, USA) searched for other possible IFITM3 variants that correlated with gene expression, levels of the IFITM3 proteins and were common in influenza patients in the USA. The search led to an IFITM3 variant known as rs34481144. They checked 86 children and adults in Memphis with confirmed influenza infections and found two-thirds of patients with the most severe symptoms carried at least one copy of the newly identified high-risk IFITM3 variant. The high-risk variant was found in just 32% of patients with milder symptoms.

The team also found an association between the newly identified high-risk variant and severe and fatal influenza infections in 265 critically ill pediatric patients hospitalized in one of 31 intensive care units nationwide. The patients did not have health problems that put them at high risk for severe influenza. Of the 17 patients in this group who died from the infection, 14 carried at least one copy of the newly identified high-risk variant. Further study revealed how binding differed between the high-risk and protective variants. Those differences led to lower levels of the IFITM3 protein in individuals with two copies of the high-risk gene variant compared to other patients. The Memphis influenza patients also had fewer of the killer T cells in their upper airways. The study identifies a new regulator of IFITM3 expression that associates with CD8+ T cell levels in the airways and a spectrum of clinical outcomes.

Paul Thomas, PhD, an immunologist and corresponding author of the study, said, “A genetic marker of influenza risk could make a life-saving difference, particularly during severe influenza outbreaks, by helping prioritize high-risk patients for vaccination, drug therapy and other interventions. These results raise hopes that this newly identified IFITM3 variant might provide such a marker.” The study was published on July 17, 2017, in the journal Nature Medicine.

Source: labmedica