ORIGINAL ARTICLE Lactoferrin and desferrioxamine are ineffective in the treatment of Helicobacter pylori infection and may enhance H. pylori growth and gastric inflammation in mice H.Q. Huynh 1,2 , M.A.F. Campbell 3 , R.T.L. Couper 2 , C.D. Tran 2 , A. Lawrence 4 , and R.N. Butler 2,5 1 Division of Pediatric Gastroenterology and Nutrition, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada 2 Gastroenterology Unit, Department of Pediatrics, Children, Youth and Women’s Health Service, University of Adelaide, Adelaide, SA, Australia 3 Numico Research Australia Pty Ltd, Oakden, Australia 4 Department of Microbiology, Children, Youth and Women’s Health Service, University of Adelaide, Adelaide, SA, Australia 5 Department of Physiology, University of Adelaide, Adelaide, SA, Australia Background Iron is essential for the growth of Helicobacter pylori and a number of animal studies have demonstrated that freely available iron increases the virulence of this bacte- rium (Bullen et al. 2005). Antimicrobial properties of lactoferrin, a potent iron-binding glycoprotein, against various bacteria and viruses have been reported (Ward and Conneely 2004). Apart from its ability to reduce the availability of free iron for pathogens, lactoferrin’s bacte- ricidal activity is attributed to the disruption of bacterial cell membrane by lactoferricin. Lactoferricin is a pepsin- derived fragment of lactoferrin that has the capacity to bind the lipid A portion of lipopolysaccharides (LPS) and increase cell permeability (Tomita et al. 1991; Brandenburg et al. 2001). Its other antimicrobial activi- ties include: disruption of biofilms, inhibiting bacterial (e.g. H. pylori) attachment to epithelial cells, intracellular invasion of other bacteria, amplifying apoptosis in infected cells and enhancing hydroxy radical production of neutrophils during phagocytosis (Valenti and Antonini 2005). Bovine lactoferrin (BLf) and desferriox- amine are potent iron chelating agents that have been shown to inhibit H. pylori growth in vitro. In addition, BLf has been shown to reduce the H. pylori load in mice (Dial et al. 1998). Keywords desferrioxamine, Helicobacter pylori infection, iron chelating agent, lactoferrin, mice, MPO. Correspondence Hien Q. Huynh, Pediatric Gastroenterology and Nutrition, Department of Pediatrics, Stollery Children’s Hospital ⁄ University of Alberta, Aberhart Centre # 1 Room 9219, 11402 University Ave NW, Edmonton, AB Canada T6G 2J3. E-mail: Hien.Huynh@ualberta.ca 2008 ⁄ 1078: received 25 June 2008, revised 27 November 2008 and accepted 28 Novem- ber 2008 doi:10.1111/j.1472-765X.2009.02557.x Abstract Aims: To evaluate the efficacy of bovine lactoferrin (BLf), recombinant human lactoferrin (rHLf) and desferrioxamine against Helicobacter pylori in vitro and in mice and also to determine whether BLf or rHLf alter gastric inflammation. Methods and Results: In vitro: Broth dilution susceptibility tests were per- formed using different concentrations of desferrioxamine, BLf and rHLf. Mur- ine trials: In the prevention trial, C57BL ⁄ 6 female mice were treated with BLf or rHLF, and then infected with the SS1 strain of H. pylori. In the treatment trial, mice were gavaged with either BLf, rHLf or desferrioxamine. In addition, gastric myeloperoxidase activity (MPO) was measured to assess gastric inflam- mation. Desferoxamine was found to have a direct bactericidal effect, while BLf and rHLf only partially suppressed H. pylori growth in vitro. However, in both prevention and treatment trials all three forms of treatment failed to reduce H. pylori load in mice. Gastric MPO activity and H. pylori load were noted to be higher with lactoferrin treatments. Conclusions: Our study does not support the use of BLf or rHLF in the treat- ment of human H. pylori infection. Interestingly, H. pylori growth and gastric inflammation appear to be enhanced by lactoferrin treatment. Significance and Impact of the Study: The mouse model is ideal for testing novel H. pylori eradicating agents. Letters in Applied Microbiology ISSN 0266-8254 ª 2009 The Authors Journal compilation ª 2009 The Society for Applied Microbiology, Letters in Applied Microbiology 1