Elevation of human 
-defensins and S100 calcium binding protein A8 and A9 in tear fluid of pterygium patients
Lei Zhou 1,
Roger W Beuerman 1*,
Leonard P Ang 2,
Choi Mun Chan 3,
Sam FY Li 4,
Fook Tim Chew 5,
and
Donald Tiang-Hwee Tan 6
1 Singapore Eye Research Institute, Singapore, Singapore; Ophthalmology, National University of Singapore, Singapore, Singapore
2 Singapore National Eye Centre, Singapore, Singapore; Ophthalmology, National University of Singapore, Singapore, Singapore
3 Singapore National Eye Centre, Singapore, Singapore
4 Chemistry, National University of Singapore, Singapore, Singapore
5 Biological Science, National University of Singapore, Singapore, Singapore
6 Singapore Eye Research Institute, Singapore, Singapore; Singapore National Eye Centre, Singapore; Ophthalmology, National University of Singapore, Singapore, Singapore
* To whom correspondence should be addressed. E-mail: rwbeuer{at}mac.com.
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Abstract |
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PURPOSE. The pathogenesis of pterygia is still not well understood. In this study we have determined that the inflammatory nature of pterygium is reflected in the protein components of the tears.
METHODS. Twelve patients with unilateral pterygium were recruited for this study. Tears were collected prior to pterygium surgery from diseased eyes and contralateral normal control eyes. Tear protein profiles obtained from diseased and control eyes were compared using SELDI. Protein identification was performed using nanoLC coupled with tandem mass spectrometry (nano-ESI-MS/MS).
RESULTS. SELDI mass spectra showed that three human 
-defensins (HNP-1, HNP-2 and HNP-3, Mw around 3.4 kDa), S100 A8 (Mw=10.8 kDa) and S100 A9 (Mw=12.7 kDa) were elevated in tears from pterygium eyes. The mean concentration (n = 7) of -defensins for pterygium eyes and fellow control eyes were 1.33 ± 0.47 µg/ml (HNP-1, pterygium eye, p < 0.015), 0.61 ± 0.23 µg/ml (HNP-2, pterygium eye, p < 0.012) and 0.17 ± 0.12 µg/ml (HNP-1, control eye), 0.02 ± 0.02 µg/ml (HNP-2, control eye) respectively. Compared to tears from eyes without pterygium, the level of S100 A8 was found to be increased between 1.4 to 13.4 (average fold change: 4.5) in eyes with pterygium and S100 A9 was elevated between 1.5 to 4.0 (average fold change: 2.3) in 4/7 patients.
CONCLUSIONS. The upregulated expression of human -defensins and S100 A8 and A9 in tear fluids of pterygium patients indicates that they may be part of the response of the ocular surface to the formation of this fibrovascular tissue or the accompanying inflammation.
Key Words:
pterygium, tears, S100 A8/S100 A9, SELDI, tear protein, defensin
