Role of surfactant protein-D in ocular bacterial infection

Abstract

Purpose Our review explains the role of surfactant protein D (SP-D) in different kinds of bacterial infection based on its presence in different ocular surface tissues. We discuss the potential role of SP-D against invasion by pathogens, with the aim of identifying new prospects for the possible mechanism of SP-D-mediated immune processes, and the diagnosis, prognosis, or treatment of ocular bacterial infection. Methods We reviewed articles about the role of SP-D in various ocular bacterial infections or infection-related ocular diseases through PubMed, Google Scholar, and the Web of Science databases. Results SP-D acts as an important immune factor that can resemble molecules in different polymerization states and that defends against pathogen invasion. The increased SP-D production and secretion in tear fluid and the cornea after ocular bacterial infections such as Staphylococcus aureus , Pseudomonas aeruginosa keratitis, and infection-related ocular diseases, was shown to have potential anti-inflammatory effects. The mechanisms of SP-D’s action against ocular bacterial infections include presenting, aggregating, opsonizing, and phagocytizing antigens, as well as regulating anti-bacterial immunity processes, including toll-like receptor-5 (TLR-5) pathway and IL-8 effect, TLR-4 and TLR-2 pathways and other possible ways remained to be elucidated in more detail. The findings demonstrate the potential of SP-D as an important clinical diagnostic biomarker prognosis predictor, and target for ocular immunotherapy. Conclusion SP-D participates in invasion by different ocular bacteria and infection-related ocular diseases through multiple immune mechanisms. This finding provides new prospects for the diagnosis, prognosis and treatment of ocular bacterial infection.

A novel ex vivo bovine corneal infection and clearance model for Neisseria gonorrhoeae, Staphylococcus aureus, and Pseudomonas aeruginosa

“…These include the epithelial barrier of the cornea, tear exchange and eye blinks, and upregulation or expression of biochemical components such as defensin, secretory immunoglobulin A, mucin glycoproteins, antimicrobial proteins, and peptides [173][174][175][176]. Innate defences of surfactant proteins A and D (SP-A and SP-D) present on the ocular surface [177], for instance, have been reported to prevent invasion of corneal epithelial cells by bacteria pathogens such as P. aeruginosa and S. aureus [172,178,179]. Although several immune responses of the ocular system are thought to exist in in vivo models, in ex vivo models the cellular and stromal constituents of the corneal tissue remain, as well as certain inherent intracellular immune elements [20].…”

More than Antibiotics: Latest Therapeutics in the Treatment and Prevention of Ocular Surface Infections

“…SP-D can aggregate pathogens and facilitate pathogenic clearance. Compared with wild-type mice, mice with the depletion of SP-D with mannan-conjugated sepharose or anti-SP-D antibody had increased susceptibility to bacterial keratitis [ 123 , 124 ]. Cysteine protease is an extracellular protease secreted by bacteria that degrades SP-D [ 125 ].…”