Expression of CD13/aminopeptidase N on human gingival fibroblasts and up-regulation upon stimulation with interleukin-4 and interleukin-13.
OBJECTIVE
Aminopeptidase N (APN)/CD13 is a multifunctional ectoenzyme that is involved in anti-inflammatory reactions, control of immune reactions and differentiation of many cellular systems. Here, we hypothesized that CD13/APN would be expressed on human gingival fibroblasts (hGF) and would contribute to the regulation of immune responses in periodontal tissue.


RESULTS
CD13/APN was expressed on hGF at the mRNA and protein levels as determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Enzymatic activities accompanying the expression were assessed by colorimetrical analysis using the synthetic substrate Leu-p-nitroanilide. We examined the possible regulation of CD13/APN expression on hGF in response to T cell-derived cytokines. T helper (Th) 2 cell type cytokines such as interleukin-4 and interleukin-13, but not interleukin-2 or interleukin-15, preferentially increased the expression of proteins as well as the enzymatic activities of CD13/APN in a dose-dependent manner. Receptors for these cytokines, the interleukin-4 receptor alpha chain, interleukin-13 receptor alpha1 chain, and interleukin-2R common gamma chain, were expressed on hGF assessed by RT-PCR or flow cytometry. hGF exhibited inhibitory effects for formyl-methionyl-leucyl-phenylalanine (FMLP)-induced polymorphonuclear leukocyte-activation that was evaluated by Mac-1 expression, and this inhibitory effect was partially recovered by pre-treatment with the APN-specific inhibitor bestatin.


CONCLUSIONS
These findings suggested that CD13/APN expressed by hGF could contribute to the anti-inflammatory response in periodontal tissue, and may be involved in disease processes mediated by Th2 cells.
Kunii
Ryotaro
R
Division of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Nemoto
Eiji
E
Kanaya
Sousuke
S
Tsubahara
Taisuke
T
Shimauchi
Hidetoshi
H
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D018826:CD13 Antigens / Q000235:genetics / Q000378:metabolism*; D002648:Child; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005881:Gingiva / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology; D018123:Receptors, Interleukin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D018709:Statistics, Nonparametric; D015854:Up-Regulation
D018793:Interleukin-13; D018123:Receptors, Interleukin; D015847:Interleukin-4; D018826:CD13 Antigens