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Friday, 17 June 2016 00:25

Dispatches from ASM Microbe: Friday

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ASM Microbe is the new conference that merges the former General Meeting with the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) to make one microbial sciences-packed meeting with something for everyone. Why institute one new meeting instead of maintaining two separate ones? Says David Hooper, Chair of the ASM Meetings Board, “This inaugural ASM Microbe meeting will, for the first time, integrate the full spectrum of the microbial sciences from basic science to translational and clinical applications, highlighting the broad transdisciplinary nature of microbiology and offering the newest information in the field.”

 

The presence of experts from  all the microbial sciences means you could meet experts on pediatric infectious disease diagnostics, viral exocytosis, RNA-mediated genetic regulation, astromicrobiology, and genomes of foodborne pathogen—all in the same line at the coffee kiosk! “Registration for the meeting has already exceeded 10,000, creating unparalleled networking opportunities,” says Hooper.

 

Yesterday (June 16th), the Keynote Session featured a conversation with Bill Gates, ably led by Dr. Richard Besser, Chief Health and Medical Officer of ABC News. The event was received by an enthusiastic opening audience. Scientists and health care workers traveled from around the country and around the world to participate in this kickoff event (if you missed the live stream of this event you can view it here).

 

In conversation, Gates discussed the efforts necessary to spread health benefits around the world. The Gates Foundation hopes to make catalytic change: small changes, such as in vaccine delivery strategies, that can have large impacts on many people. Increases in vaccination rates, access to affordable drugs, and development of neglected tropical disease therapies are all required goals for a more equitable global health strategy. Gates closed by stressing the role of innovation in microbiology to achieve these goals.

 

A microcosm of microbiome

 

Each day of ASM Microbe, this blog will focus on a major research theme and some of the highlighted research being presented at the conference around that theme. Today we kick off with the human microbiome!

 

As many readers are aware, the White House recently announced its National Microbiome Initiative. This initiative is geared toward understanding the communities of microorganisms living together in diverse environments—within or on a host, in the soil, in man-made structures, in water systems, and in the atmosphere. The impact of the human microbiome on our health is so profound that it deserves its own post.

 

Manipulating the microbiome

 

Now that they have characterized  members of microbiomes of the oral cavity, gastrointestinal tract, and skin, researchers have shifted their research toward manipulating these populations  to enhance human health. This morning’s session on prebiotics is an excellent example of how our diet can influence the GI microbiome, which in turn can influence our health. The definition of prebiotic has itself been shifting ($), as described in a recent perspective authored by several of this morning’s panelists. Rather than define prebiotic by the outcome on microbial composition, the impact on overall microbial function of the microbiome (e.g., metabolic breakdown and changes in the localized tissue environment) may be a better way to gauge the therapeutic potential of a prebiotic, such as inulin-type fructans (ITF) or human milk.

 

While prebiotics such as human milk help establish a healthy microbiome, other prebiotics help modify an established unhealthy microbiome. A prime example comes from obesity research, where scientists have correlated obese- or lean-derived bacterial populations with effects on GI tissue architecture, lipid and polysaccharide metabolism, and low-level inflammation. Mouse microbiome transfer studies make a strong causative case for gut microbes influencing host biology, and several panelists propose targeting these gut microbial communities via prebiotics as one tool toward weight management.

 

Nathalie Delzenne and Laure Bindels are investigating the use of prebiotics (e.g., nonfermentable carbohydrates) to control some of the effects of metabolic disorders. Research in recent years has shown metabolic syndrome-associated symptoms, including hyperglycemia, inflammation, and hepatic steatosis, are treatable in mice given nondigestible/nonfermentable carbohydrates (e.g., ITF or arabinoxylans) as dietary supplements. Arabinoxylans also improve insulin resistance in a diet-induced mouse model of type 2 diabetes, while ITF fermentation by gut microbes has potential for cancer therapeutic applications. The challenge for the future of prebiotics lies in conducting well-controlled human trials.

 

Dietary supplementation with prebiotics may someday be the easiest way to ensure a healthy microbiome, but it’s important to note that microbes are already producing a number of metabolic byproducts that affect the microbial population and function. A session held Sunday, June 19th, will discuss microbial products and their effects on the host and/or other microbes. The products and their effects vary from antimicrobial peptides that promote competition, discussed by Kevin Roelofs, to the production of secondary bile acids that affect Clostridium difficile colonization, discussed by Casey Theriot, to microbial metabolite-mimics that modulate host immunity, discussed by Somduta Saha. Learning how microbes manipulate their environment provides future microbial manipulation targets.

 

The darker side of the microbiome will also be covered in a number of sessions. A Saturday, June 18th session highlights the role of the human microbiome in harboring antibiotic resistance genes. This "resistome" exists in part due to the high density of microbes and to the prevalence of antimicrobial agents in our arsenal used against infection. The gut (covered by Willem van Schaik), pediatric gut (covered by Aimee Moore), and oral cavity (covered by Adam Roberts) will be discussed as major reservoirs that can harbor drug-resistant microbial members without detection or deleterious health effects. Real danger lies in these resistance genes being passed between species to generate multidrug-resistant strains. For more on antimicrobial resistance, tune into Sunday’s special ASM Microbe edition blog.

 

Expanding the microbiome community

 

There are a number of nonbacterial microbiome members who have often been overlooked. Using gene or genome sequencing to identify microbial composition biases researchers toward microbes containing the target sequence for primer binding. The 16S rRNA gene, often used in microbiome studies, is only present in bacteria. Concurrent to the prebiotic session is one on the mycobiome—the fungus among us. Fungi can be sequenced using their internal transcribed spacer (ITS) sequence, and while microbiome studies increasingly include fungi in the molecular probes, a pubmed search for "mycobiome" produces 67 results, compared to the 24,771 results for "microbiome."

 

Only a single panelist, Thomas Auchtung, discussed the normal mycobiome, which can be influenced by the fungi that grow preferentially on a human host and the fungi continually encountered by chance due to spores found in our air, food, and water. Most panelists focused on the role of endogenous fungi in states of immunosuppression. In the case of HIV infection that has progressed to AIDS, as discussed by Mahmoud Ghannoum; stem cell transplantation, as discussed by Ying Taur; or cancer, as discussed by Samuel Shelburne, the immune system is no longer able to restrain fungal growth. These small, single-celled eukaryotes can have large impacts on human health and should be studied along with their bacterial counterparts.

 

And don’t forget about the virome! ASM President Lynn Enquist chose this important area to highlight during the President’s Forum, occurring June 18th. Viruses, perhaps more than their bacterial counterparts, have bad PR, being studied mostly in the context of pathogenic infection. In fact, studies published by one of the two feature speakers, Herbert (Skip) Virgin, highlight “bacterial microbiome and virome”—even though "microbiome" should imply all microbial inhabitants of a community! Virgin’s talk focuses on the role that bacterial microbiome constituents play in viral interaction with human host cells, modulation of antiviral immunity by bacterial microbiota, and the effects of viral and bacterial populations on each other. The coevolved relationships between bacteria, virus, and host are poorly understood, and present potential not only for future therapeutic strategies, but also for deeper conceptual advances about these interkingdom interactions.

 

Understanding interkingdom interactions and continuing to identify microbiome members are laudable microbiome-related goals. This is one reason why ASM is excited to have partnered with the Kavli Foundation to present the Kavli Ideas Challenge in partnership with the American Chemical Society and American Physical Society. This methods- and tools-based challenge hopes to catalyze innovative means to study microbial function.

 

Of course, coverage of the human microbiome only includes a few specialized types of microbial communities. Tune in tomorrow for a continuation of the Dispatches from ASM Microbe for an update on agricultural, environmental, and infrastructural microbiomes!

 

 

Last modified on Saturday, 18 June 2016 13:20
Julie Wolf

ASM Communications Social Media Specialist Julie Wolf spent her research career focused on medical mycology and infectious disease. Broadly interested in microbiology and scientific communication, she has taught at Long Island University and the community biolab Genspace and has written for the Scientista Foundation and Scholastic’s Science World magazine. Follow her on Twitter for more ASM and Microbiology highlights at @JulieMarieWolf.

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