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Gut Check: Compounds from the Human Gut Microbiome Could Fight Drug-Resistant Bacteria

Roughly 100 trillion microbes coexist and compete for limited resources in the human gut. To survive, they may have to get creative. Scientists at the University of Pennsylvania (UPenn) and Stanford University hypothesized that some of the innovative ways that

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Roughly 100 trillion microbes coexist and compete for limited resources in the human gut. To survive, they may have to get creative. Scientists at the University of Pennsylvania (UPenn) and Stanford University hypothesized that some of the innovative ways that gut microbes use to beat out the competition could have potential use as antibiotics. They explored this idea in a new paper published in Cell titled, “Mining human microbiomes reveals an untapped source of peptide antibiotics.”

In the search for effective treatments against drug-resistant bacteria, scientists in the laboratory of César de la Fuente, PhD, an assistant professor in bioengineering and chemical and biomolecular engineering at UPenn, have hunted for antibiotic candidates from a range of sources including the genetic information of extinct creatures like Neanderthals and wooly mammoths to masses of bacteria analyzed using artificial intelligence. For this study, they worked with scientists in the lab of Ami Bhatt, MD, a professor in medicine (hematology) and genetics at Stanford.

“One of our primary goals is to mine the world’s biological information as a source of antibiotics and other useful molecules,” de la Fuente said. “Rather than relying on traditional, painstaking methods that involve collecting soil or water samples and purifying active compounds, we harness the vast array of biological data found in genomes, metagenomes, and proteomes. This allows us to uncover new antibiotics at digital speed.”

Using computational tools, the scientists surveyed the gut microbiome data from nearly 2,000 people. Their analysis of over 400,000 proteins from the study participants revealed dozens of potential peptide antibiotics. They selected and synthesized 78 to test against bacterial cultures as well as animal models. Over half of the peptides tested inhibited bacterial growth of either friendly or pathogenic bacteria. The lead candidates from these tests proved to be “anti-infective in both murine skin abscess and deep thigh infection models. Notably, prevotellin-2 from Prevotella copri presented activity comparable to the commonly used antibiotic polymyxin B,” the researchers wrote.

“Interestingly, these molecules have a different composition from what has traditionally been considered antimicrobial,” said Marcelo Torres, a research associate in the de la Fuente lab, and the paper’s first author. “The compounds we have discovered constitute a new class, and their unique properties will help us understand and expand the sequence space of antimicrobials.”

Furthermore, “identifying prevotellin-2, which has activities on par with one of our antibiotics of last resort, polymyxin B, was very surprising to me,” Bhatt said. “This suggests that mining the human microbiome for new and exciting classes of antimicrobial peptides is a promising path forward for researchers and doctors, and most especially for patients.”

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Related questions

01How stable is the antibody?

A crucial question often addressed during preclinical development focuses on the in vivo stability of therapeutic antibodies. Increasing the half-life of a therapeutic antibody has several benefits ranging from higher treatment efficacy to increased advantages for the patients who will have a fewer number of therapy sessions and a reduced cost. Given these compelling benefits, following the identification of therapeutic antibodies with the desired specificity, developers usually subject them to a refinement step to increase their stability. This process is often hindered by the lack of reliable experimental tools to predict the half-life of antibodies in patients. The major hurdle of using mouse models to predict antibody stability in the serum lies in the way immunoglobulin proteins are processed by the organism. In mammals, most proteins circulating in the serum undergo constant uptake by endothelial cells and are routed through the endosomes to the lysosomal compartment for degradation. In the endosomes, immunoglobulin G (IgG) proteins are recognized and bound by a transmembrane protein, called the neonatal Fc receptor (FcRn), which mediates their recycling to the plasma membrane and subsequent release back into the serum. As a result, the half-life of IgGs are significantly extended by this mechanism. Since most therapeutic antibodies belong to the IgG class, this recycling system is very relevant for their relative stability in the body. Remarkably, the relative affinity between IgGs and FcRn is extremely disparate between different species, with the mouse receptor showing a much higher affinity than its human counterpart.

Source: www.genengnews.com ↗
02Undruggable or unscreenable?

Another obstacle to discovering new PPI inhibitors is the lack of libraries designed to hunt for them, points out Philippe Roche, PhD, senior scientist at the Integrative Structural and Chemical Biology team at the Cancer Research Center of Marseilles, France. “If you screen PPIs using libraries that were designed for kinases or GPCRs, that’s why you don’t get a lot of good results,” he says. To that end, his group began assembling a library focused on orthosteric inhibitors of PPIs. The result was 2P2Idb, a hand-curated, structural database cataloguing orthosteric inhibitors of PPIs for which the interface had been 3D characterized. From analyzing these known PPI inhibitors, and what structures they had in common, Roche and his colleagues developed a model to predict whether compounds would likely inhibit PPIs. Using this method, 2P2Idb creates an enriched screening library that dramatically increases the hit rate compared to standard libraries. Having proven their success with a small library of 1600 compounds, they are in the process of expanding the library to 10,000 compounds. Once that’s published, “the idea is to make this library available to labs around the world,” Roche says. “We will provide the library free of charge for people to be able to screen PPI targets.”

Source: www.genengnews.com ↗
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Peptide Therapy Guide Editorial Team

Editorial team for Peptide Therapy Guide.

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