Anti-inflammatory effects of troxerutin are mediated through elastase inhibition

Context: Obesity is a chronic low-grade inflammatory state associated with immune cell infiltration into the adipose tissue (AT). We hypothesize that the anti-obesity and anti-inflammatory effects of troxerutin (TX) are mediated through inhibition of Elastase.

Objective: To determine the inhibitory effect of TX on Elastase in vitro and in tumor necrosis factor alpha (TNFα) induced 3T3-L1 adipocytes and the molecular interaction of TX with human neutrophil Elastase (HNE).

Materials and methods: Differentiated 3T3-L1 adipocytes were pretreated with TX, elastatinal (ELAS) or sodium salicylate (SAL) before exposure to TNFα. Lipid accumulation, Reactive Oxygen Species (ROS) generation and oxidant-antioxidant balance were examined. The mRNA and protein expression of TNFα, interleukin-6, monocyte chemoattractant protein-1, Adiponectin, Leptin, resistin, chemerin, and Elastase were analyzed. Elastase inhibition by TX and ELAS in a cell free system and docking studies for HNE with TX and ELAS were performed.

Results: TX, ELAS or SAL pretreatment had lowered lipid droplets formation and TG content. TX suppressed ROS generation, oxidative stress and improved antioxidant status. The expression of inflammatory cytokines and Elastase was downregulated while that of Adiponectin was upregulated by TX. The concentration required to produce 50% inhibition in vitro (IC₅₀) was 11.5 μM for TX and 16.9 μM for ELAS. TX showed hydrogen bonding and hydrophobic interactions with Elastase.

Discussion: TNFα induces inflammation of 3T3-L1 cells through Elastase activation. TX inhibits Elastase activity, downregulates expression and binds with Elastase.

Conclusion: The antioxidant and anti-inflammatory activities of TX in AT could be of relevance in the management of obesity.