A mechanism study of electroacupuncture for dry eye syndrome by targeting conjunctival cytokine expressions.

Aim: To discuss the immunological mechanism in electroacupuncture (EA) treatment of dry eye syndrome (DES) by targeting the changes in conjunctival cytokine expression profile. Method: Eligible DES patients were randomized into an EA group (EAG) or an acupuncture group (AG). The ocular surface disease index (OSDI), amount of tear production, and tear film break-up time (BUT) were observed to evaluate the efficacy. Conjunctival cells were collected from both effective and invalid cases to observe the expressions of cytokines by protein microarray. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used for functional cluster and signaling pathway analysis of the differentially expressed proteins. Enzyme-linked immunosorbent assay (ELISA) was used to verify the specific differential proteins. Result: After treatment, OSDI dropped and BUT extended in both groups, and the tear production increased only in the EAG (all P < .01). Compared with the AG, the improvement in tear production was more significant in the EAG (P < .01). There were 17 differentially expressed conjunctival cytokines between the effective and invalid cases in the EAG, and those expressed higher than the limit of detection (LOD) included monocyte chemoattractant protein 1 (MCP-1), macrophage colony-stimulating factor (M-CSF), regulated on activation in normal T-cell expressed and secreted (RANTES) and tissue inhibitor of metalloproteinases 1 (TIMP-1). GO analysis showed that the differential cytokines were mainly involved in cellular interaction, signaling pathways and reactions to stimuli. KEGG analysis revealed that the signaling pathways of these cytokines were mainly responsible for interactions between cytokines or between cytokines and their receptors, such as Jak-STAT signaling pathway, chemokine signaling pathway, and tumor necrosis factor signaling pathway. Conclusion: EA can effectively treat DES by improving the symptoms, increasing tear secretion and extending BUT, which is possibly related to its regulation on the conjunctival cytokine expressions.