Sea Anemone Kunitz Peptide HCIQ2c1 Reduces Histamine-, Lipopolysaccharide-, and Carrageenan-Induced Inflammation via the Suppression of Pro-Inflammatory Mediators.

Inflammation is a physiological response of the immune system to infectious agents or tissue injury, which involves a cascade of vascular and cellular events and the activation of biochemical pathways depending on the type of harmful agent and the stimulus generated. The Kunitz peptide HCIQ2c1 of sea anemone Heteractis magnifica is a strong protease inhibitor and exhibits neuroprotective and analgesic activities. In this study, we investigated the anti-inflammatory potential of HCIQ2c1 in histamine- and lipopolysaccharide (LPS)-activated RAW 264.7 macrophages as well as in LPS-induced systemic inflammation and carrageenan-induced paw edema models in CD-1 mice. We found that 10 μM HCIQ2c1 dramatically decreases histamine-induced intracellular Ca²⁺ release and LPS-induced reactive oxygen species (ROS) production in RAW 264.7 macrophages. Moreover, HCIQ2c1 significantly inhibited the production of LPS-induced tumor necrosis factor α (TNF-α), inducible NO-synthase (iNOS), and 5-lipoxygenase (5-LO) but slightly influenced the IL-1β and cyclooxygenase-2 (COX-2) expression level in macrophages. Furthermore, intravenous administration by HCIQ2c1 at 0.1 mg/kg dose reduced LPS-induced TNF-α, IL-1β, COX-2, and iNOS gene expression in CD-1 mice. The subplantar administration of HCIQ2c1 at 0.1 mg/kg dose to mice significantly reduced carrageenan-induced paw edema by a factor of two, which is comparable to the effect of diclofenac at 1 mg/kg dose. Thus, peptide HCIQ2c1 has a strong anti-inflammatory potential by the attenuation of systemic and local inflammatory effects through the inhibition of intracellular Ca²⁺ release, the production of ROS and pro-inflammatory cytokines, and enzymes involved in arachidonic acid metabolism.