Immunomodulatory effects of piper nigrum extract on macrophage cell J774A.1

Abstract

Piper nigrum (P. nigrum) or black pepper is one of Thai herbs which has been used both as seasoning and traditional medicine. This plant has healing properties in relieving flatulence or dyspepsia. P. nigrum composed of several phytochemical compounds. Preliminary study showed that the water extract of P. nigrum stimulated nitric oxide (NO) production in macrophage cells. NO is one of inflammatory mediators using for host defense mechanism. The present study then aim to investigate the immunomodulatory effects of the water extract of P. nigrum on macrophage cells. The results showed that the water extract of P. nigrum at concentration of 3.125-100 µg/ml increased phagocytosis by macrophage cells. Moreover, P. nigrum has stimulatory effect on NO production. NO is an important molecule involved in destruction of microbes. Furthermore, this extract at 12.5-50 µg/ml also increased the expression of inducible nitric oxide synthase (iNOS), the enzyme which catalyzes NO production. In part of oxygen-independent pathway, the water extract of P. nigrum promoted the production of lysozyme M, the enzyme capable of hydrolyzing bacteria. The extract at 50 µg/ml also enhanced the expression of Dectin-1 receptor, the receptor which recognizes fungal cell wall. The water extract of P. nigrum at 12.5-50 µg/ml promoted the expression of the pro-inflammatory cytokines including IL-1β, IL-6 and TNF-α. Furthermore, the water extract also enhanced the expression of costimulatory molecules necessary for T cell activation including B7-1, B7-2 and ICAM-1. This study suggests that the water extract of P. nigrum is ability to stimulate macrophage functions which involve in immunomodulation. It may be benefit in developing new drug and also ensuring the efficiency of Thai herb.