Extract of Alpinia officinarum Suppresses Enteropathogenic Escherichia coli (EPEC) Lipopolysaccharide (LPS) Induced Inflammation in J774 A.1 Macrophages

Abstract

Molecules with bi-functional activities are preferred targets in drug discovery research today. In this study, a possible dual role (anti-inflammatory and anti-bacterial activity) of a plant extract has been discussed. As an initiative, the extract is found to suppress inflammation caused by endotoxin release from an enteric pathogen. Enteropathogenic Escherichia coli (E. coli) (EPEC O127:H6) causes persistent diarrhea and continues to be a major health problem among infants in developing countries. Host inflammatory response during EPEC infection is weak when compared to infections caused by other enteric pathogens. This is due to the suppression of intestinal inflammatory response by type III secreted proteins of EPEC during infection process. The weak inflammatory response is thus possibly due to disruption of tight junctions, which in turn facilitate recruitment of macrophages from the underlying lamina propria or shedding of bacterial products like lipopolysaccharide (LPS) during antibiotic mediated bacterial lysis. Since intestinal cells are non-responsive to LPS, the inflammatory response would be elicited by the intestinal macrophages present at the site of infection. Apart from commercial LPS from E. coli O111: B4, LPS was isolated from EPEC and used for inducing inflammatory markers like TNFα, IL-1β, IL-8 and TLR4 in J774 A.1 murine macrophage like cells to make this study clinically relevant. Alpinia officinarum is a traditional, perennial herb used widely in China and India for treating arthritis and gastrointestinal disorders. The ethyl acetate extract of Alpinia officinarum effectively suppressed EPEC LPS * To whom correspondence should be addressed: Center for Biotechnology, Anna University, Chennai-600025, Tamil Nadu, India. Tel.: +91-44-22350772; Fax: +91-44-22350299; E-mail: lakshmibs@annauniv.edu # These authors contributed equally to this work.induced inflammatory response thereby exhibiting potential in a clinical scenario, wherein diarrhea induced by EPEC or products of its lysis is either a consequence of macrophage induced inflammation or antibiotic treatment or due to a potential, yet to be analyzed, anti-bacterial activity of Alpinia officinarum extract against EPEC.

Tackling multiple antibiotic resistance in enteropathogenic Escherichia coli (EPEC) clinical isolates: a diarylheptanoid from Alpinia officinarum shows promising antibacterial and immunomodulatory activity against EPEC and its lipopolysaccharide-induced inflammation

“…The active ethyl acetate extract of A. officinarum reported previously [8] was subjected to column chromatography using an open column dry packed with 100-200 mesh-size silica gel. The column was eluted with a gradient solvent system.…”

“…PBMCs were isolated as described previously [8]. Briefly, heparinised venous blood from healthy donors was obtained with their informed consent.…”

“…LPS was isolated from wild-type EPEC 2348/69 as described previously [8] and 1 g/mL of EPEC LPS was used to stimulate PBMCs.…”

“…The inflammatory response to LPS-mediated bacterial infections is a consequent manifestation that causes additional tissue damage to the host, particularly due to bacterial persistence and antimicrobial resistance. Since intestinal epithelia are unresponsive to LPS, the inflammatory response is initiated by intestinal macrophages or polymorphonuclear neutrophils of the immune system [8]. Since all classes of antibiotics, except macrolides, have been shown to induce inflammation [9], there is a requirement for alternative forms of therapy with molecules that possess antibacterial and anti-inflammatory properties.…”

“…Moreover, ethyl acetate extracts of Alpinia galanga have been reported for their antibacterial activity [13]. Recently, we reported that the ethyl acetate extract of A. officinarum suppressed EPEC LPS-induced inflammation in J774 A.1 macrophage-like cells [8].…”