Anti-inflammatory effect of garlic 14-kDa protein on LPS-stimulated-J774A.1 macrophages

Abstract

Context: Garlic 14-kDa protein is purified from garlic (Allium sativum L.) which is used in traditional medicine and exerts various immunomodulatory activities.

Objective: The present study investigated the suppressive effect of garlic 14-kDa protein on LPS-induced expression of pro-inflammatory mediators and underlying mechanism in inflammatory macrophages.

Materials and methods: J774A.1 macrophages were treated with 14-kDa protein (5–30 μg/ml) with/without LPS (1 μg/ml) and the production of inflammatory mediators such as prostaglandin E2 (PGE2), TNF-α, and IL-1β released were measured using ELISA. Nitric oxide (NO) production was determined using the Griess method. The anti-inflammatory activity of 14-kDa protein was examined by measuring inducible nitric oxide synthase and cyclooxygenase-2 proteins using western blot. The expression of nuclear NF-κB p65 subunit was assessed by western blot.

Results: Garlic 14-kDa protein significantly inhibited the excessive production of NO, PGE, TNF-α, and IL-1β in lipopolysaccharide (LPS)-activated J774A.1 macrophages in a concentration-related manner without cytotoxic effect. Western blot analysis demonstrated that garlic 14-kDa protein suppressed corresponding inducible NO synthase expression and activated cyclooxygenase-2 protein expression. The inhibitory effect was mediated partly by a reduction in the activity and expression of transcription factor NF-κB protein.

Conclusion: Our results suggested, for the first time, garlic 14-kDa protein exhibits anti-inflammatory properties in macrophages possibly by suppressing the inflammatory mediators via the inhibition of transcription factor NF-κB signaling pathway. The traditional use of garlic as anti-inflammatory remedy could be ascribed partly to 14-kDa protein content. This protein might be a useful candidate for controlling inflammatory diseases and further investigations in vivo.

• Allium sativum L.
• cyclooxygenase-2
• inducible nitric oxide synthase
• J77A.1 macrophages
• lipopolysaccharide

Declaration of interest

The authors declare that they have no conflicts of interest. The authors alone are responsible for the content of this manuscript. This research was supported by the Research Council of Mashhad University of Medical Sciences (MUMS) vice president (Grants # 86315, 86326, and 86539).