Mucosal NOD2 expression and NF-kappaB activation in pediatric Crohn's disease.
BACKGROUND
Recent advances in the pathogenesis of Crohn's disease (CD) have suggested that an aberrant innate immune response initiates the cascade of events leading to T-cell activation and to disease development. NOD2 protein, which is mainly expressed by innate immunity cells, appears to play a key role against bacteria by triggering a host defense response through the activation of the transcriptor factor NF-kappaB and a consequent proinflammatory cytokine production. The present study was aimed at investigating the expression and activity of NOD2, NF-kappaB, and of 2 proinflammatory cytokines, TNFalpha and IL-1beta, in mucosal biopsies of CD affected children compared to healthy controls.


METHODS
In all, 22 children with active CD and 10 matched controls were entered in the study. mRNA and protein expressions were detected using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot; NF-kappaB binding activity was assessed by electromobility gel shift assay (EMSA).


RESULTS
NOD2 and IL-1beta mRNAs were upregulated in CD children. Protein levels of NOD2, TNFalpha, and nuclear NF-kappaB, as well as the binding activity of NF-kappaB to a consensus DNA sequence, were significantly increased in inflamed mucosa of patients as compared to controls. Moreover, NF-kappaB activity was strongly upregulated in patients also when bound to the NOD2 promoter site. No difference was seen between patients and controls when NF-kappaB binding activity was determined in the uninflamed tissue.


CONCLUSIONS
This study suggests that altered mechanisms regulating NOD2 induction, NF-kappaB activation and cytokine production may contribute to dysregulate the innate immune response underlying pediatric CD.
Stronati
Laura
L
Section of Toxicology and Biomedical Sciences, Enea, Rome, Italy.
Negroni
Anna
A
Merola
Paola
P
Pannone
Veronica
V
Borrelli
Osvaldo
O
Cirulli
Manuela
M
Annese
Vito
V
Cucchiara
Salvatore
S
D000293:Adolescent; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001706:Biopsy; D015153:Blotting, Western; D002648:Child; D003113:Colonoscopy; D003424:Crohn Disease / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005500:Follow-Up Studies; D005765:Gastrointestinal Agents / Q000627:therapeutic use; D015870:Gene Expression; D005838:Genotype; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D000069285:Infliximab; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008297:Male; D016328:NF-kappa B / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D053473:Nod2 Signaling Adaptor Protein / Q000096:biosynthesis / Q000235:genetics*; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D000911:Antibodies, Monoclonal; D005765:Gastrointestinal Agents; D053583:Interleukin-1beta; D016328:NF-kappa B; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab