Unveiling the Innate and Adaptive Immunity Interplay: Global Transcriptomic Profiling of the Host Immune Response in Candida albicans Endophthalmitis in a Murine Model

Abstract

Intraocular fungal infection poses a significant clinical challenge characterized by chronic inflammation along with vision impairment. Understanding the host defense pathways involved in fungal endophthalmitis will play a pivotal role in identifying adjuvant immunotherapy. Clinical isolates of Candida albicans (15,000 CFU/μL) were intravitreally injected in C57BL/6 mice followed by enucleation at 24 and 72 h postinfection. Histopathological analysis was performed to evaluate the retinal changes and the disease severity. RNA-seq analysis was conducted on homogenized eyeballs to assess the relevant gene profiles and their differentially expressed genes (DEGs). Pathway enrichment analysis was performed to further annotate the functions of the DEGs. Histopathological analysis demonstrated a higher disease severity with increased inflammatory cells at 72 hpi and transcriptome analysis revealed 27,717 DEGs, of which 1493 were significant (adj p value ≤0.05, FC ≥ 1.5). Among these, 924 were upregulated, and 569 were downregulated. Majority of the upregulated genes were associated with the inflammatory/host immune response and signal transduction and enriched in the T-cell signaling pathway, natural killer cell-mediated cytotoxicity, C-type receptor signaling pathway, and NOD-like receptor signaling pathway. Furthermore, inflammation-associated genes such as T-cell surface glycoprotein CD3, cathelicidin antimicrobial peptide, and lymphocyte cellspecific protein tyrosine kinase were enriched, while pathways such as MAPK, cAMP, and metabolic pathways were downregulated. Regulating the T-cell influx could be a potential strategy to modulate excessive inflammation in the retina and could potentially aid in better vision recovery in fungal endophthalmitis.