Periodic Reporting for period 1 - DEBUGGING-LPS (Deciphering and Exploiting the chemical features of Silent Lipopolysaccharides: a gift from gut microbiota)
Reporting period: 2022-10-01 to 2025-03-31
The gut hosts an abundant and diverse community of microorganisms known as the gut microbiota. Despite the immune system’s constant surveillance, the mechanisms by which this microbial population, primarily bacteria, establish harmless or even beneficial interactions with the human host remain poorly understood. The story gets more intricate if one considers the massive presence of Gram-negative bacteria in the gut, whose outer membrane is rich in lipopolysaccharides (LPSs). Known for their ability to potently trigger, in a structure-dependent manner, inflammatory immune responses in mammals, LPSs are typically associated with harmful bacteria and adverse health outcomes. However, they also decorate the membranes of harmless and beneficial Gram-negative bacteria composing the gut microbiota. This paradox suggests that these bacteria must produce LPSs with a “different chemistry”, which is tolerated by the immune surveillance, thereby supporting the resilience of beneficial microbiota.
Deciphering the unique chemistry that allows this immunological “silence” poses a significant challenge and is an exciting frontier in innate immunity research. The DEBUGGING-LPS project aims at decrypting the “chemical” language spoken by LPS in the gut and at leveraging this knowledge for health-related applications. The intrinsic overarching goal of the project is to break the dogma of LPS as only a foe, leaving space for a new concept: i.e. LPS no longer as a “toxic” bacterial product rather as a microbial “signal” indispensable for the proper functioning of our body. This cutting-edge concept holds the potential to redefine how we harness microbial products for therapeutic advancements.
To reach its goals, DEBUGGING-LPS has been conceived as a project in which wet organic chemistry devoted to complex glycoconjugate analysis plays a major role. Therefore, organic chemistry represents the “core” discipline and the driving force of the project itself. Complementing this, DEBUGGING-LPS extensively incorporates cutting-edge structural biology techniques to achieve a deeper understanding of its targets. Furthermore, by leveraging advanced cellular immunology studies, it will uncover unprecedented functional information about one of the most well-known bacterial glycoconjugates. This integrative approach promises to make a significant impact on both the fields of Glycoscience and Chemical Biology.
Deciphering the unique chemistry that allows this immunological “silence” poses a significant challenge and is an exciting frontier in innate immunity research. The DEBUGGING-LPS project aims at decrypting the “chemical” language spoken by LPS in the gut and at leveraging this knowledge for health-related applications. The intrinsic overarching goal of the project is to break the dogma of LPS as only a foe, leaving space for a new concept: i.e. LPS no longer as a “toxic” bacterial product rather as a microbial “signal” indispensable for the proper functioning of our body. This cutting-edge concept holds the potential to redefine how we harness microbial products for therapeutic advancements.
To reach its goals, DEBUGGING-LPS has been conceived as a project in which wet organic chemistry devoted to complex glycoconjugate analysis plays a major role. Therefore, organic chemistry represents the “core” discipline and the driving force of the project itself. Complementing this, DEBUGGING-LPS extensively incorporates cutting-edge structural biology techniques to achieve a deeper understanding of its targets. Furthermore, by leveraging advanced cellular immunology studies, it will uncover unprecedented functional information about one of the most well-known bacterial glycoconjugates. This integrative approach promises to make a significant impact on both the fields of Glycoscience and Chemical Biology.
A comprehensive set of wet organic chemistry approaches has been employed to isolate and purify LPS from a huge number of bacterial strains with the aim of providing a collection of chemical structures that will help decrypting the language spoken by LPS in the gut. The methodologies involved extraction and purification protocols, selective chemical degradations, further purification, followed by detailed structural characterisation of LPS components using NMR spectroscopy and high-resolution mass spectrometry. Most of these purified LPS molecules have already been assessed for their immunological properties in various human cell lines and inspected for binding by specific carbohydrate-recognition proteins involved in immune response modulation.
As a result, the growing library of LPS structures from previously unexplored gut bacteria is being enriched with functional data. This provides precious insights into how the chemical features of LPSs influence immune responses, offering a clear picture of the molecular distinctions between “beneficial” and “harmful” LPS.
Overall, these scientific achievements and those that will derive from the next three years of DEBUGGING-LPS activities are expected to pave the way for developing targeted therapies to regulate inflammatory responses, advance next-generation vaccine production, and enhance translational research, ultimately improving human health.
As a result, the growing library of LPS structures from previously unexplored gut bacteria is being enriched with functional data. This provides precious insights into how the chemical features of LPSs influence immune responses, offering a clear picture of the molecular distinctions between “beneficial” and “harmful” LPS.
Overall, these scientific achievements and those that will derive from the next three years of DEBUGGING-LPS activities are expected to pave the way for developing targeted therapies to regulate inflammatory responses, advance next-generation vaccine production, and enhance translational research, ultimately improving human health.
Since its beginning, this project has embraced an interdisciplinary approach, which resulted in significant advances beyond state-of-the-art knowledge and technologies in the Glycoscience research field already within its first two years. The groundbreaking structural and functional insights already published, along with those in preparation, highlight how diverse, complex and heterogenous is the chemistry of LPS from harmless gut microbes and how these chemical features are reflected in equally uncommon immunological behaviours. Looking ahead, the project aims at contributing to exploiting the diverse array of "silent" LPS chemotypes and their derivatives to inspire the design of innovative immune-therapeutics conceived to enhance human health and wellbeing.