Hi, I’m Sandra.

Abstract

Canine cranial cruciate ligament (CCL) injuries are a common orthopedic condition inflicting joint instability, pain, and chronic synovial fibrosis, contributing to post-traumatic osteoarthritis (PTOA) development. These biological alterations to the damaged knee are often paralleled in human joint diseases as well, supporting the value of the canine model in further understanding the underlying process behind osteoarthritis. Despite this relevance, systematic pipelines connecting biological data to actionable therapeutic targets are limited.

This study aimed to identify dysregulated genes in CCL-injured canine synovium and rank candidate genes with Food and Drug Administration (FDA)-approved drugs in order of therapeutic potential. RNA-sequencing data from CCL-injured and healthy canine synovium were filtered for genes statistically significant based on an adjusted p-value <0.05 and a log2 fold-change >1.

Top 150 upregulated genes were ranked and g:Profiler was used to map resulting canine genes to human orthologs. Utilizing DAVID, functional enrichment analysis was performed to identify relevant biological pathways with clusters highlighting Il-17 signaling, inflammatory cytokines, collagen deposition, and extracellular matrix organization and remodeling.

The resulting 41 genes were analyzed using comprehensive literature review to ultimately identify five high-priority, therapeutically actionable gene-drug pairs: ADAMTS4 and Doxycycline, PTGS2 (COX-2) and Celecoxib, CCR7 and Fingolimod, IL1B and Anakinra, IL6 and Tocilizumab.

These findings establish a reliable pipeline linking canine CCL injury transcriptomics to clinically actionable therapeutic treatments, highlighting promising candidates for drug repurposing in PTOA and offering deeper insight into underlying mechanisms of osteoarthritis in both canines and humans.

Abstract

Impacting over 240 million individuals globally and more than 32 million in the U.S., Osteoarthritis (OA) is the most common form of arthritis worldwide. Traditionally understood as a mechanical disease, synovial inflammation and dysregulated cellular communication are now known to play a critical role in OA progression. This study aimed to characterize and map fibroblast-immune communication niches, supporting the identification of therapeutic targets and development of effective disease interventions.

Healthy and OA synovial single-cell RNA sequencing (scRNA-seq) data (GSE216651) was analyzed using Seurat to characterize fibroblast and immune populations, differential gene expression, and functional enrichment. LIANA was used to infer candidate ligand-receptor interactions while spatial transcriptomic data (GSE294277) was analyzed using Giotto to map transcriptional signatures and identify communication hubs.

Heterogeneous fibroblast and immune populations were identified, with prominent OA-associated distinctions among APOD+, inflammatory lining, lining fibroblast and resident macrophage groups, which were prioritized for downstream communication analysis. Ligand-receptor predictions revealed greater inferred fibroblast-macrophage and macrophage-fibroblast communication in OA compared to healthy tissue, with PRG4-CD44 representing one of the most prominent recurrent interactions.

Spatial analysis identified increased median representation of fibroblast, macrophage, immune, and matrix-remodeling signatures within OA and identified three candidate fibroblast-macrophage communication hubs, although spatial differences were not statistically significant within the limited sample units. Integration of scRNA-seq and spatial transcriptomics prioritized five candidate interactions: PRG4-CD44, FN1-CD44, FN1-PLAUR, TIMP1-CD63, and VIM-CD44.

Overall, these findings highlight the potentially pivotal role of spatial fibroblast-immune crosstalk within OA pathogenesis, offering a guide to future research and advancements in OA therapeutics.