Targeted Transcriptomic Screen of Pneumococcal Genes Expressed during Murine and Human Infection.

The advent of pneumococcal conjugate vaccines led to the near disappearance of most of the included serotypes in high-income settings but also the rise of nonvaccine-type colonization and disease. Alternative strategies, using genetically conserved proteins as antigens, have been evaluated preclinically and clinically for years, so far unsuccessfully. One possible explanation for the failure of these efforts is that the choice of antigens may not have been sufficiently guided by an understanding of the gene expression pattern in the context of infection. Here, we present a targeted transcriptomic analysis of 160 pneumococcal genes encoding bacterial surface-exposed proteins in mouse models, human colonization, and human meningitis. We present the overlap of these different transcriptomic profiles. We identify two bacterial genes that are highly expressed in the context of mouse and human infection: SP_0282, an IID component of a mannose phosphotransferase system (PTS), and SP_1739, encoding RNase Y. We show that these two proteins can confer protection against pneumococcal nasopharyngeal colonization and intraperitoneal challenge in a murine model and generate opsonophagocytic antibodies. This study emphasizes and confirms the importance of studies of pneumococcal gene expression of bacterial surface proteins during human infection and colonization and may pave the way for the selection of a protein-based vaccine candidate.

Novel Corrector for Variants of SLC6A8: A Therapeutic Opportunity for Creatine Transporter Deficiency.

Mutations in creatine transporter SLC6A8 cause creatine transporter deficiency (CTD), which is responsible for 2% of all cases of X-linked intellectual disability. CTD has no current treatments and has a high unmet medical need. Inspired by the transformational therapeutic impact of small molecule "correctors" for the treatment of cystic fibrosis, which bind to mutated versions of the CFTR ion channel to promote its trafficking to the cell surface, we sought to identify small molecules that could stabilize SLC6A8 as a potential treatment for CTD. We leveraged a novel chemoproteomic technology for ligand discovery, reactive affinity probe interaction discovery, to identify small-molecule fragments with photoaffinity handles that bind to SLC6A8 in a cellular environment. We synthesized a library of irreversible covalent analogs of these molecules to characterize in functional assays, which revealed molecules that could promote the trafficking of mutant SLC6A8 variants to the cell surface. Further medicinal chemistry was able to identify reversible drug-like small molecules that both promoted trafficking of the transporter and also rescued creatine uptake. When profiled across the 27 most prevalent SLC6A8 missense variants, we found that 10-20% of patient mutations were amenable to correction by our molecules. These results were verified in an endogenous setting using the CRISPR knock-in of selected missense alleles. We established in vivo proof-of-mechanism for correctors in a novel CTD mouse model with the P544L patient-defined variant knocked in to the SLC6A8 locus, where treatment with our orally bioavailable and brain penetrant tool corrector increased brain creatine levels in heterozygous female mice, validating correctors as a potential therapeutic approach for CTD.