Heterozygous nucleotide-binding oligomerization domain-2 mutations affect monocyte maturation in Crohn's disease.
OBJECTIVE
To investigate the function of monocytes in Crohn's disease (CD) patients and to correlate this with disease-associated nucleotide-binding oligomerization domain-2 (NOD2) gene variants.


METHODS
Monocytes from 47 consecutively referred CD patients and 9 healthy blood donors were cultured with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF), and stimulated with lipopolysaccharide (LPS) or muramyldipeptide (MDP), the putative ligand of NOD2.


RESULTS
We found that monocytes from CD patients differentiated in vitro to mature dendritic cells (DCs), as determined by immunophenotype and morphology. NOD2 genotype was assessed in all subjects, and we observed high CD86 expression on immature and LPS-stimulated DCs in NOD2 mutated CD patients, as compared with wtNOD2 CD patients and controls. By contrast, CD86 expression levels of DCs induced to maturity with MDP derived from NOD2-mutated subjects were comparable to those of normal subjects. The amount of IL-12p70 in patient-cell cultures was larger than in controls after LPS treatment, but not after treatment with MDP.


CONCLUSIONS
Our results suggest that DCs obtained from patients with mutations in the NOD2 gene display an activated phenotype characterized by high CD86 expression, but have a diminished response to MDP when compared to the terminal differentiation phase. We speculate that the altered differentiation of monocytes might lead to an imbalance between inflammation and the killing ability of monocytes, and may be relevant to the pathogenesis of CD.
Granzotto
Marilena
M
Laboratory of Immunology, Institute of Child Health IRCCS Burlo Garofolo, Via dell'Istria 65/1, Trieste 34137, Italy. granzotto@burlo.trieste.it
Fabbro
Elisa
E
Maschio
Massimo
M
Martelossi
Stefano
S
Quaglia
Sara
S
Tommasini
Alberto
A
Presani
Gianni
G
Ventura
Alessandro
A
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000483:Alleles; D051940:B7-2 Antigen / Q000378:metabolism; D016022:Case-Control Studies; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D003424:Crohn Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D005260:Female; D006579:Heterozygote; D006801:Humans; D007107:Immune System / Q000473:pathology; D018664:Interleukin-12 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000473:pathology*; D009154:Mutation / Q000235:genetics*; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics*
D051940:B7-2 Antigen; D008070:Lipopolysaccharides; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D018664:Interleukin-12; D000119:Acetylmuramyl-Alanyl-Isoglutamine