50 © 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd Parasite Immunology , 2009, 31, 50–56 DOI: 10.1111/j.1365-3024.2008.001073.x Blackwell Publishing Ltd Effect of Nippostrongylus brasiliensis L3 ES on inflammatory mediator gene transcription in lipopolysaccharide lung inflammation M. ZHAO, D. M. BROWN, J. MACCALLUM & L. PROUDFOOT School of Life Sciences, Napier University, Edinburgh, UK SUMMARY The anti-inflammatory properties of parasitic helminths have been largely linked to their excretory–secretory (ES) products. Some studies have noted a lack of TNF-α production and limited recruitment of neutrophils into the lungs after Nippostrongylus brasiliensis infection. We previously reported that instillation of ES from L3 larvae of N. brasiliensis to the lungs could inhibit the recruitment of neutrophils on a background of LPS-induced inflammation. A similar reduction in neutrophil recruitment was observed in this study. This reduction was associated with the significant inhibition in gene transcription of the adhesion molecule, ICAM-1, and the chemokine, MIP- 2 in bronchoalveolar lavage (BAL) cells. The LPS-stimulated gene transcription of the pro-inflammatory cytokines TNF-α and IL-1β was also significantly reduced by L3 ES. Inducible nitric oxide synthase (iNOS) is normally elevated in classically activated macrophages, however, in this case gene transcrip- tion of iNOS was inhibited by L3 ES and may suggest a pheno- type change to anti-inflammatory. The general inhibition of pro-inflammatory mediators observed in this study suggests that infective stage L3 larvae excrete and/or secrete inhibitory products capable of modifying the normally potent LPS inflammatory response. Keywords anti-inflammatory, bronchoalveolar lavage (BAL), chemokines, cytokines, lung, Nippostrongylus brasiliensis INTRODUCTION Parasitic nematode infection can cause significant disease in humans and animals but at the same time has a Th2-like, anti-inflammatory phenotype which may be of benefit to the host. Nematode excretory–secretory (ES) products are known to contain a number of different immunomodulatory molecules which could interfere with, or modulate, the inflammatory process (1,2). There has also been interest in development of parasitic nematodes, or their ES, as therapeutic agents. The pig whipworm Trichuris suis has been used in trials to treat inflammatory bowel disease (3) and an ES product of a filarial nematode has recently been demonstrated to have dramatic modulatory effects in a mouse model of rheumatoid arthritis (4) and on mast cell degranulation (5). The subject of our study is Nippostrongylus brasiliensis, a parasitic nematode of the rat, which is widely used as a model for human parasitic hookworm disease as it follows a similar migratory route through the lungs and induces immunological responses comparable with human infection (6). The delay in recruitment of inflammatory leucocytes to the rat lung in our previous study of N. brasiliensis infection (7) led us to the belief that anti-inflammatory mechanisms could be active in the parasite ES. This idea was encouraged by our experiments (8) using ES from L3 larvae (L3 ES) of N. brasiliensis, which indicated that parasite products could interfere with neutrophil recruitment to the lung in response to bacterial lipopolysaccharide (LPS). Neutrophil recruit- ment to sites of acute inflammation is an important step in the eradication of invading pathogens such as bacteria, however, the role of neutrophils in helminth infection remains unclear. In the present investigation, we examined the extent of an anti-inflammatory effect of N. brasiliensis ES in a rat model of lung inflammation using LPS. LPS is a highly potent activator of the innate immune response (9) and its interaction with lung cells will lead to induction of a succession of inflammatory mediators. Neutrophils interact with chemokines, cytokines and adhesion molecules for Correspondence: Dr Lorna Proudfoot, School of Life Sciences, Napier University, 10 Colinton Road, Edinburgh, EH10 5DT, UK (e-mail: l.proudfoot@napier.ac.uk). Received: 22 July 2008 Accepted for publication: 3 October 2008