Latent-period stool proteomic assay of multiple sclerosis model indicates protective capacity of host-expressed protease inhibitors

Carlos G Gonzalez,Howard L Weiner,Stephanie K Tankou,Laura M Cox,Joshua E Elias,Ellen P Casavant

doi:10.1038/s41598-019-48495-5

Abstract

Diseases are often diagnosed once overt symptoms arise, ignoring the prior latent period when effective prevention may be possible. Experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, exhibits such disease latency, but the molecular processes underlying this asymptomatic period remain poorly characterized. Gut microbes also influence EAE severity, yet their impact on the latent period remains unknown. Here, we show the latent period between immunization and EAE’s overt symptom onset is characterized by distinct host responses as measured by stool proteomics. In particular, we found a transient increase in protease inhibitors that inversely correlated with disease severity. Vancomycin administration attenuated both EAE symptoms and protease inhibitor induction potentially by decreasing immune system reactivity, supporting a subset of the microbiota’s role in modulating the host’s latent period response. These results strengthen previous evidence of proteases and their inhibitors in EAE and highlight the utility stool-omics for revealing complex, dynamic biology.

Highlights

Both chronic and acute diseases are classically characterized by overt symptoms and their related molecular signatures
We found that depleting a subset of microbes with the antibiotic vancomycin prior to immunization broadly attenuated the increased protease inhibitor levels, suggesting microbes sensitive to this antibiotic were responsible for immune system priming prior to immunization
After quality filtering, we observed 2,781 operational taxonomic units (OTUs) from all mice and time points, 91 of which were included at the L6 taxonomic level of the QIIME software output

Summary

Introduction

Both chronic and acute diseases are classically characterized by overt symptoms and their related molecular signatures. Previous research has shown MS patients harbor altered gut microbial communities compared to healthy controls[4,5,6] In line with this evidence, EAE induction can be heavily influenced by the presence of specific microbial community members, the host-microbiome interactions that lead to these results are not entirely delineated[7]. We leveraged temporal 16S rRNA microbial sequencing and shotgun proteomics of mouse stool in order to measure the intricate interplay of host response, microbes, and disease. This work pointed to correlations between specific protease inhibitors and microbes prior to the onset of disease, providing a basis for further mechanistic studies focused on the interplay between immune regulation and microbiome composition. We found that depleting a subset of microbes with the antibiotic vancomycin prior to immunization broadly attenuated the increased protease inhibitor levels, suggesting microbes sensitive to this antibiotic were responsible for immune system priming prior to immunization

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