An investigation into the effect and mechanisms of action of nicotine in inflammatory bowel disease.
OBJECTIVE
To determine the effect of nicotine on colonic inflammation in the trinitrobenzenesulphonic acid (TNBS) model of inflammatory bowel disease in comparison with sulphasalazine.


METHODS
Male Wistar rats were used for the in-vivo and ex-vivo studies. In-vitro studies were performed using human leukemia peripheral blood monocyte cells (THP-1 cells) grown in continuous culture.


METHODS
Rats were given access to either nicotine (5 or 100 microg/mL) or sulphasalazine (375 microg/mL) in their drinking water for 10 or 2 days respectively before and 3 days after TNBS administration. THP-1 cells were treated with nicotine (10(-14) to 10(-11) M) for 2 h before and after stimulation with 3 microg/mL lipopolysaccharide (LPS).


METHODS
Inflammation in the TNBS model was assessed by measuring the tissue myeloperoxidase activity, leukotriene B4 concentration, inducible nitric oxide protein expression, the ex-vivo production of tumour necrosis factor alpha (TNFalpha), macroscopic damage score, plasma corticosterone levels and by a qualitative histological evolution. The effect of nicotine on TNFalpha production in LPS stimulated THP-1 monocyte cells in-vitro was also determined. Statistical comparisons were made using the Mann-Whitney U-test for the macroscopic damage score and an ANOVA for all other parameters.


RESULTS
TNBS treated rats given access to 100 microg/mL nicotine in their drinking water had a marked reduction in several of the markers of inflammation compared to control TNBS treated rats, but a greater reduction was found at 5 microg/mL nicotine or 375 microg/mL sulphasalazine, the latter producing comparable reductions in inflammation to the low dose nicotine. Nicotine also caused a significant reduction in TNFalpha release from THP-1 cells.


CONCLUSIONS
Nicotine reduced inflammation in the TNBS model of colonic damage confirming the use of nicotine in IBD although the choice of dose requires further investigation. The mechanism of action of nicotine does not involve increased corticosterone levels, but may be a consequence of a reduction in TNFalpha or leukotriene B4 production.
Sykes
A P
AP
Biosciences Department, University of Hertfordshire, Hatfield, Hertfordshire, UK. a.p.sykes@herts.ac.uk
Brampton
C
C
Klee
S
S
Chander
C L
CL
Whelan
C
C
Parsons
M E
ME
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D007938:Leukemia; D007975:Leukotriene B4 / Q000032:analysis; D008297:Male; D009538:Nicotine / Q000627:therapeutic use*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012460:Sulfasalazine / Q000627:therapeutic use; D014302:Trinitrobenzenesulfonic Acid; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D000894:Anti-Inflammatory Agents, Non-Steroidal; D014409:Tumor Necrosis Factor-alpha; D007975:Leukotriene B4; D012460:Sulfasalazine; D009538:Nicotine; D014302:Trinitrobenzenesulfonic Acid; D009195:Peroxidase; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat