NOD2/CARD15 genotype influences MDP-induced cytokine release and basal IL-12p40 levels in primary isolated peripheral blood monocytes.
BACKGROUND
The functional link between mutations in NOD2 and Crohn's disease (CD) has not been entirely elucidated. The 1007fs mutation results in loss of NF-kappaB activation in response to muramyl dipeptide (MDP) but has also been linked to an increased IL-1beta processing and IL-12 release.


METHODS
We investigated the basal and MDP-triggered mRNA expression and protein release for TNF-alpha, IL-10, IL-1beta, and IL-12p40 in peripheral blood monocytes from 40 CD patients and 15 healthy individuals with different NOD2 genotypes.


RESULTS
Monocytes from individuals with 2 mutated NOD2 alleles (homozygous and compound-heterozygous individuals) displayed an impaired release of TNF-alpha and IL-10 but also of IL-1beta and IL-12p40 in response to MDP. In contrast to other NOD2 variants, the presence of at least 1 1007fs allele in double-mutated individuals completely abrogated NOD2 receptor function. Interestingly, monocytes from CD patients with 2 mutated NOD2 alleles displayed significantly higher basal levels of IL-12p40 in cell culture supernatants compared to wildtype CD patients and control individuals (P = 0.002 and P = 0.008, respectively). This was regardless of the IL23R genotype and was not mirrored by increased IL-12p40 plasma levels in these individuals.


CONCLUSIONS
The CD-associated NOD2 variants lead, in a dose- and mutation-dependent manner, to an impaired release of TNF-alpha, IL-10, IL-1beta, and IL-12p40 in response to MDP. The finding of increased basal levels for IL-12p40-related cytokines in monocytes with 2 mutated NOD2 alleles is likely to set a new link between NOD2 mutations and the inflammatory mechanisms underlying CD.
Beynon
Vanessa
V
Department of Surgery, Innenstadt, University of Munich, Germany.
Cotofana
Sebastian
S
Brand
Stephan
S
Lohse
Peter
P
Mair
Anja
A
Wagner
Stefanie
S
Mussack
Thomas
T
Ochsenkühn
Thomas
T
Folwaczny
Matthias
M
Folwaczny
Christian
C
Glas
Jürgen
J
Török
Helga-Paula
HP
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology; D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D016022:Case-Control Studies; D003424:Crohn Disease / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005838:Genotype; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D053762:Interleukin-12 Subunit p40 / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha
D000276:Adjuvants, Immunologic; D053762:Interleukin-12 Subunit p40; D053583:Interleukin-1beta; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D000119:Acetylmuramyl-Alanyl-Isoglutamine