Abstract
Purpose: :
To identify the main differences in a proteomic analysis between tear samples from healthy patients, dry eye syndrome and Sjögren disease.
Methods: :
Three groups of subjects were defined as follows: Six patients with Sjögren disease (SD), two patients with non-Sjögren dry eye syndrome (NSD) and six healthy subjects (H). Tear samples from all subjects were collected and 10 mcg/mL of proteins were resolved in 10% SDS-PAGE, gels were Coomasie blue stained, densitometric analysis of the main proteins was performed. The main bands identified were cut, and in order to identify proteomic differences between groups, MALDI-TOF was performed.
Results: :
In all groups two main proteins were identified, one of 80 kDa and one of aprox 60 kDa. When densitometric analysis was performed, a two-fold increase was observed in the 60 kDa protein in the SD group compared to both NSD and H groups. The same manner, a two-fold increase was observed in the 80 kDa protein in the NSD and H groups compared to the SD group. MALDI-TOF analysis determined that five of the eight 60 kDa proteins of either H and NSD groups corresponded to seric albumin, however only two out of the six proteins of SD group matched with seric albumin and one of these two matched only with 21 peptides. By the other hand, five out of eight 80 kDa proteins corresponded to lactoferrin in either H and NSD groups, meanwhile, only one of the six 80 kDa proteins of the SD group corresponded to lactoferrin and this matched only with 13 peptides. Interestingly, two more 80 kDa proteins were identified in the SD group: myeloperoxidase and transferrin precursor.
Conclusions: :
Although it has already been reported that there is an increase in the ratio albumin/lactoferrin in SD, these findings suggest that proteins resolved in SDS-PAGE are not the same proteins between NSD and H compared to SD, moreover, it may propose posttranslational or micro heterogeneity differences in Sjögren disease.
Keywords: cornea: tears/tear film/dry eye • proteomics • cornea: basic science