Abstract
Purpose :
Diabetic patients are known to have a higher incidence of infection, with increased disease severity and an increased rate of multi-drug resistance. To understand the underlying mechanisms, we used mRNA-seq and bioinformatics to identify biological processes (BPs) unique for DM corneas during bacterial infection.
Methods :
Streptozotocin-induced type 1 (T1) and db/db type 2 (T2) DM mice were infected with Pseudomonas (P) aeruginosa. High-throughput RNA sequencing (RNA-seq), in combination with comprehensive bioinformatics, were performed to identify differentially expressed genes (DEGs) and their related biological processes (BPs) during Pa infection. To confirm the involvement of the identified BPs, siRNA knockdown of key modulators was performed, and its effects on bacterial keratitis were assessed.
Results :
While 10,000 cfu Pa are required to cause infectious keratitis in normoglycemic (NL) corneas, 750 and 2000 cfu were enough for T1 and T2DM corneas infection, respectively. mRNA-seq of the corneas under 8 conditions, NL and T1DM at 0, 6 hpi, 1 dpi and 3 dpi with similar severity of keratitis, revealed 17,117 protein coding genes, representing residential and infiltrating neutrophils (PMN), macrophages (MF), dendritic, and other immune cells. Gene Ontology (GO) analysis of these DEGs revealed that among many BPs identified, negative regulation of TLR signaling was specific for NL. In contrast, positive regulation of TLR signaling was found in DM corneas. Targeting TREML1, a positive regulator of TLR signaling, improves the outcome of Pa keratitis.
Conclusions :
DM causes excessive TLR signaling in response to bacterial infection, leading to hyperinflammation and severe bacterial keratitis. The involvement of other unique BPs in mediating increased susceptibility and severity of bacterial keratitis in DM corneas warrants further investigation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.