Secretory phospholipase A2 deposition on contact lenses and its effect on bacterial adhesion.
OBJECTIVE
Secretory phospholipase A2 (sPLA2) is a potent antibacterial enzyme in tears and has been found to kill Staphylococcus aureus rapidly in vitro. The purpose was to determine whether sPLA2 deposition is associated with contact lens (CL) type, if sPLA2 remains active on CLs, and if this has an effect on bacterial adhesion.


METHODS
Ionic (etafilcon A) and nonionic (Polymacon) high-water, soft CLs were used. CLs were worn for 6 hours (daily wear, n = 39) or 6 nights on an extended-wear schedule (n = 25). Tears were collected from patients and worn contact lenses were removed and protein and active enzymes extracted for estimation of their levels. The number of S. aureus adhering to sPLA2-soaked CLs in vitro was also quantified.


RESULTS
There was no significant difference in the concentration of sPLA2 in tears between groups of daily CL wearers. Significantly less sPLA2 was recovered from Polymacon CLs for both daily and extended wear compared with etafilcon A CLs (daily wear: 3 vs. 5 ng/lens; extended wear: 3 vs. 6 ng/lens; P < 0.05). sPLA2 activity correlated with protein amounts from lenses. Relatively less active sPLA2 was recovered from Polymacon contact lenses. sPLA2 reduced adhesion of Staphylococcus to contact lenses in vitro.


CONCLUSIONS
Etafilcon A CLs absorb more active sPLA2 than Polymacon CLs, which increases with length of CL wear. The sequestering of sPLA2 onto CLs did not affect amounts of the enzyme in tears. sPLA2 adsorbed to a CL can reduce the viable Staphylococcus adhering to the CL, which may protect the eye from colonization by this pathogen.
Vision Cooperative Research Centre, The University of New South Wales, Sydney, New South Wales, Australia. e.hume@visioncrc.org
Emma B H
EB
Hume
Nerida
N
Cole
Alpesh
A
Parmar
Maxine E
ME
Tan
Yulina
Y
Aliwarga
Tracey
T
Schubert
Brien A
BA
Holden
Mark D P
MD
Willcox
D000042:Absorption; D001422:Bacterial Adhesion; D003262:Contact Lenses, Extended-Wear / Q000382:microbiology; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D004789:Enzyme Activation; D004867:Equipment Design; D006801:Humans; D009994:Osmolar Concentration; D010741:Phospholipases A / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D054467:Phospholipases A2; D013211:Staphylococcus aureus / Q000502:physiology*; D013666:Tears / Q000737:chemistry
D010741:Phospholipases A; D054467:Phospholipases A2