Abstract
Purpose: :
sPLA2 is a family of enzymes with at least ten known isoforms in humans and mice that show diversified physiological function and distribution. The sPLA2-IIa isoform has been noted in several human inflammatory diseases, including RA, colitis and ASHD. Recently we have shown that sPLA2-IIa plays a significant role in modulating inflammation when the ocular surface is compromised, as in dry eye (DE) disease. The fact that C57BL/6 mice lack functional sPLA2-IIa yet develop DE disease suggests that other sPLA2 isoforms may play active roles in ocular surface inflammation. This study explores sPLA2 isoforms in 2 murine strains that are typically used for DE studies, BALB/c and C57BL/6.
Methods: :
BALB/c DE mice were treated by scopolamine-air ventilation. BALB/c or C57BL/6 control mice received no treatment. CN, CNJ epithelia or LG of each mouse were collected, and their total RNAs were quantitatively analyzed by real-time reverse-transcription PCR (qRT2-PCR) using established primers from QIAGEN: pla2g1b, 2a, 2d, 2e, 2f, pla2g3, pla2g4a, pla2g5, pla2g6, pla2g10, pla2g12a, 12b, and PLA2 receptor pla2r1. Data represent mean of 3 repeats normalized with GAPDH.
Results: :
(1) Five isoforms (4a, 5, 6, and 12a and 12 b) and PLA2 receptor (pla2r1) were expressed in all three tissues of all tested mice; while three (1b, 2e and 3) were not detected in any tissue of any tested mouse. (2) Four isoforms (2a, 2d, 2f and 10) showed tissue- or strain-specific expression patterns. For example, 2a was only detected in CNJ of BALB/c mice, not in CN or LG, nor in C57BL/6 mice; 2d showed much more in CNJ than in LG, none in CN; 2f expressed in both CN and CNJ, none in LG; pla2g10 prefers CNJ over CN, none in LG. (3) DE induction specifically changed several isoforms expression in CNJ, such as pla2g2a (sPLA2-IIa), pla2g5 (sPLA2-V) and pla2g2f (sPLA2-IIF). The latter has not been reported. (4) DE induced pla2r1 expression in all three tissues. (5) sPLA2 isoform expressing patterns were very different between un-treated BALB/c and C57BL/6 mice, suggesting C57BL/6 may use different strategies or sPLA2 isoform set in association with ocular surface inflammation.
Conclusions: :
Our results indicate that different animal or species may use different sPLA2 isoforms to modulate the ocular surface inflammatory responses. Studies elucidating the role(s) of these sPLA2 isoforms will improve our understanding of inflammation of the ocular surface and may provide targets in treating ocular surface inflammation, such as in DED.This study was supported in part by the Martin and Toni Sosnoff Foundation.
Keywords: inflammation • gene/expression • immunomodulation/immunoregulation