Does nicotine influence cytokine profile and subsequent cell cycling/apoptotic responses in inflammatory bowel disease?
BACKGROUND
Smoking differentially influences susceptibility to the inflammatory bowel diseases (IBDs) Crohn's disease (CD) and ulcerative colitis (UC). We investigated the effects of nicotine on cytokine, cell cycle, and apoptotic responses in peripheral blood mononuclear cells (PBMCs) from IBD patients and healthy controls (HCs).


METHODS
PBMCs from IBD patients and HC were stimulated with lipopolysaccharide (LPS; 1 microg/mL) or phytohemagglutinin (PHA, 5 or 0.5 microg/mL), +/- nicotine (1, 10, 100 microg/mL). Cytokines (IL1beta, IL2, IL10, IL12/IL23p40, TGFbeta, TNFalpha) were measured in supernatants at 24 hours. After 72 hours cells were analyzed by flow cytometry for cell cycle and apoptosis. Statistical modeling was used to identify interactions between cytokines and cell cycle / apoptosis and minimize confounding effects.


RESULTS
Stimulation by LPS and PHA (5 microg/mL) increased IL12/IL23p40 production from CD and UC versus HC (P < 0.05); PHA (0.5 microg/mL) increased IL1beta in UC and decreased TGFbeta from CD and UC (P < 0.01). In all groups, nicotine reduced LPS- and PHA (0.5 microg/mL)-stimulated production of IL1beta, IL10, TGFbeta, and TNFalpha (P < 0.001). Cell cycle analysis showed that PHA, but not LPS, induced proliferation and decreased G(0)/G(1) resting cells in CD and UC versus HC (P < 0.001). Nicotine decreased PHA-stimulated S-phase proliferation and increased G(0)/G(1) resting cells (P < 0.01). Modeling showed independent associations between IL12/IL23p40 and apoptosis (P = 0.01), IL1beta and resting cells (P = 0.006), TNFalpha and proliferating cells (P < 0.001). Disease activity and smoking habit had no effect.


CONCLUSIONS
Dysregulated cytokine profiles in UC and CD are associated with specific alterations in cell cycle responses; these effects may be modified by nicotine, and potentially by anticytokine therapies.
Aldhous
Marian C
MC
Gastrointestinal Unit, School of Clinical and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, UK. maldhous@ed.ac.uk
Prescott
Robin J
RJ
Roberts
Simon
S
Samuel
Kay
K
Waterfall
Martin
M
Satsangi
Jack
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D017209:Apoptosis / Q000276:immunology / Q000502:physiology*; D015415:Biomarkers / Q000032:analysis; D002453:Cell Cycle / Q000276:immunology / Q000502:physiology*; D002478:Cells, Cultured; D002648:Child; D003093:Colitis, Ulcerative / Q000276:immunology / Q000503:physiopathology; D003424:Crohn Disease / Q000276:immunology / Q000503:physiopathology; D016207:Cytokines / Q000032:analysis / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000276:immunology / Q000503:physiopathology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009538:Nicotine / Q000494:pharmacology*; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects; D055815:Young Adult
D015415:Biomarkers; D016207:Cytokines; D009538:Nicotine