Talat Roome, Anam Razzak, Saeed Khan, Masood Hameed Khan, Shaheen Faizi, Lubna Abidi and Lubna
Molecular Pathology, Department of Pathology, Dow diagnostic Reference and Research Laboratory, Dow International Medical College, Dow University of Health Sciences Karachi, Pakistan
During MCP-1/CCR2 monocyte chemotaxis, two intracellular phospholipases (PLA2) regulate the pathogenesis of plaque formation. Calcium independent iPLA2ß controls speed and directionality of migration via F-actin polymerization and calcium dependent cPLA2α regulate speed of chemotaxis through soluble epoxide hydrolase pathway. Opuntiol/Opuntioside-I shown anti-inflammatory potential and in this study are evaluated against MCP-1 signaling to introduce novel anti-atherogenic agent.
Inhibitory effect against monocyte migration was monitored in thioglycolate-induced mouse peritoneal inflammation using both in vivo and adoptive transfer mouse models. In addition to this human monocytes migration was analyzed by using microchamber chemotaxis assay and under agarose assay along with microscopic studies. Opuntiol/Opuntioside-I reduced human monocyte migration 50-90% against MCP-1 in vitro and also found to be effective upon oral treatment in mouse peritonitis model. Confocal microscopy demonstrated they interfered with iPLA2β translocation to cell membrane in MCP-1 stimulated migrating cells and its gradient dependent migration under-agarose assay was also suppressed. Likewise, MCP-1 induced- and iPLA2β dependent- actin polymerization was also inhibited in cells treated with 10µM of Opuntioside-I. In adoptive transfer mouse model, it inhibited cell migration by 80% induced by 4% thioglycolate at 10 μg/ml. Whereas, in the presence of EETs as substrate in human cellular assay, these compounds suppressed the sEH enzymatic activity in a dose dependent manner and found to reduce the production of DHETs by 70 -80%.
In conclusion, Opuntiol/Opuntioside-I interfere with phospholipase A2 signaling in MCP-1/CCR2 stimulated monocyte via inhibiting iPLA2β activity and down regulate the sEH pathway suggesting that these compounds are potential therapeutic agent against atherosclerosis.