Abstract
Purpose :
Diabetic patients are known to have a higher incidence of infection, increased disease severity, and a higher rate of multi-drug resistance. To understand the underlying mechanisms, we employed mRNA-seq and bioinformatics to identify biological processes associated with the heightened susceptibility and severity of bacterial keratitis in diabetic B6 mice.
Methods :
Streptozotocin-induced type 1 diabetes mellitus (T1DM) mice were infected with Pseudomonas aeruginosa (Pa). High-throughput RNA sequencing (RNA-seq), in combination with comprehensive bioinformatics, was utilized to identify differentially expressed genes (DEGs) and their related biological processes (BPs) during Pa infection. To validate the involvement of the identified BPs, we performed inhibition studies targeting key modulators and assessed their effects on bacterial keratitis.
Results :
While 10,000 cfu of Pa were required to induce infectious keratitis in normoglycemic (NL) corneas, only 750 cfu were necessary for infection in T1DM corneas. Gene Ontology (GO) analysis of DEGs revealed that among the numerous BPs identified, efferocytosis was exclusively observed in NL corneas at 1 and 3 days post-infection (dpi). During Pa infection, the expression of chemotactic "find me" signals, such as Cx3CL1 recognized by Cx3cr1, and "eat me" signals, phosphatidylserine (PtdSer) recognized by MerTK and bridged by ProS1, was suppressed, while the key "don't-eat-me" signal CD47 was augmented in DM corneas compared to NL corneas. Targeting CD47 significantly improved the outcome of Pa keratitis in DM corneas.
Conclusions :
Hyperglycemia reduces macrophage infiltration and impairs efferocytosis, leading to increased susceptibility and severity of bacterial keratitis in DM corneas. Promoting efferocytosis may enhance the outcomes of bacterial keratitis treatment in patients receiving antibiotics.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.