112. Activated Gene Pathways in Post-Infectious Hydrocephalus (PIH): Proteogenomics and the PIH Expressome

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Authors: Albert Isaacs, MD; Sarah Morton, MD, PhD; Christine Hehnly, BS; R. Reid Townsend, MD, PhD; Diego Morales, MS; James Broach, PhD; Joseph Paulson, PhD; David Limbrick Jr., MD, PhD; Steve Schiff, MD, PhD (Calgary, Canada)

Introduction:

Ependymal gliosis, arachnoiditis, and multi-loculated infiltrates that typically characterize postinfectious hydrocephalus (PIH) suggests PIH may be propagated by host-immune responses that scars and obstructs cerebrospinal fluid (CSF) pathways. Defining the PIH host-immune response is imperative for defining disease pathophysiology, defining CSF biomarkers, and ultimately developing adjunct strategies to prevent hydrocephalus. With a central hypothesis that PIH host-immune response is mediated by specific activated gene pathways, we utilized proteogenomics, an innovative approach that integrates deep-scale proteomics with next-generation transcriptomics to define critical network and pathway level linkages to probe the molecular mechanisms of this disease.

Methods:

Proteomics and RNA-seq transcriptomics were concurrently performed on intraoperative CSF samples of sub-Saharan Africa infants under 3 months of age with PIH (n=64) and hydrocephalus not attributed to PIH (NPIH, n=36). PIH infants were sub-categorized based on CSF 16S rRNA sequence analysis consistent with Paenibacillus infection status. Abundance and differential expression analyses identified between-group variations. Gene ontology, ingenuity pathway and gene-set enrichment analyses parsed the omics’ data into biological functions. Integrating proteomic and RNA-seq data we were able to define specifically activated pathways within our cohort of PIH patients.

Results:

Of 616 proteins and 10622 genes identified by proteomics and RNA-seq respectively, there was enrichment for leukocyte extravasation, antigen presentation, macrophage phagocytosis and neuroinflammation expressomes in PIH compared to non-PIH. Paenibacillus status correlated with expressomes related to neutrophil activation and extracellular matrix organization. Proteogenomic integration yielded candidate biomarkers of PIH at the time of surgery.

Conclusion:

PIH host-immune expressomes in this cohort were identified and proteogenomic integration facilitated identification of activated pathways with higher predictive values for combined RNA and protein data compared to either approach alone.  The identified candidate biomarkers can be cross-validated with targeted assays and further evaluated for monitoring and pharmacological therapies to treat neonatal meningitis and ventriculitis to prevent PIH.

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