3. 1 Conjunctival gene Expression of Enzymes of Sphingolipids Metabolism:
Gene expression of enzymes of the sphingolipid metabolism was evaluated in the conjunctival cells of VKC cases compared to age matched control. A significant increase in the expression of the enzymes involved in the removal of ceramide to form sphingosine namely, Alkaline ceramidase (ACER) (p<0.05); Sphingosine kinase (SPHK1) that forms S1P from sphingosine (p<0.001); Sphingosine 1- phosphate lyase (SGPL) that acts on S1P to breakdown to phosphoethanolamine (p<0.001) were seen. CERK which converts ceramide to C1P was raised though not statistically significant. But UDP- Glucose ceramide glucosyl transferase (UGCG) which forms glycosphingolipid from ceramide was increased significantly (p<0.05) in VKC patients(Figure 2A) . However, the enzyme, acid sphingomyelinase (ASMA) involved in ceramide synthesis from sphingomyelin was significantly reduced (p<0.01). No significant difference between R-VKC and NR-VKC were observed in the gene expressions studied (data not shown).