Up-regulated gene expression in the conjunctival epithelium of patients with Sjögren's syndrome.
OBJECTIVE
To elucidate the pathogenesis of ocular surface abnormalities in patients with Sjögren's syndrome (SS) by comparing global gene expression patterns in conjunctival epithelial cells from normal individuals and SS patients.


METHODS
The study population consisted of 56 subjects (26 SS patients and 30 normal volunteers). RNA extracted from their conjunctival epithelial cells was subjected to introduced amplified fragment length polymorphism (iAFLP), a competitive PCR-based gene expression assay, to measure gene expression in the 56 samples against 931 genes. Data were analyzed by two-dimensional clustering analysis and discriminant analysis. Disease-related genes were identified and the feasibility of gene expression-based diagnosis of SS was examined.


RESULTS
Two-dimensional clustering- and discriminant analysis clearly distinguished between SS patients and normal subjects. Of 931 genes tested, 34 were significantly up-regulated and 12 were significantly down-regulated in SS (p<0.05). Up-regulated genes included kallikrein 7 (x 15.8) and small proline-rich protein 2A (x 9.6), markers for the terminal differentiation of epidermis, and the inflammation-related genes HLA-DR and IL-6. Monokine-induced-by-gamma-interferon, i.e. c-fos, fibronectin, amphiregulin, defensin beta 2, and keratin 16, -6b and -6c were also up-regulated. Among the 12 down-regulated genes, interferon-gamma receptor 1 was most notable (x1/27.3).


CONCLUSIONS
The up-regulated expression of keratin 6 and -16, small proline-rich protein 2A, and kallikrein 7 in the conjunctival epithelium of SS patients suggests an anomalous keratinization pattern. Epithelial thickening may be due to amphiregulin and/or c-fos-stimulated cell cycle progression. The up-regulation of monokine-induced-by-gamma-interferon, HLA-DR, keratin 6b, -6c, and -16 suggests that in SS, interferon-gamma may play an important role in the altered gene expression in the conjunctival epithelium.
Kawasaki
Satoshi
S
Kyoto Prefectural University of Medicine, 465 Kajii-cho, Hirokoji-agaru, Kawaramachi-dori, Kamigyo-ku, Kyoto 602-0841, Japan. skawasak@eye.ophth.kpu-m.ac.jp
Kawamoto
Shoko
S
Yokoi
Norihiko
N
Connon
Che
C
Minesaki
Yuichi
Y
Kinoshita
Shigeru
S
Okubo
Kousaku
K
D000368:Aged; D066258:Amphiregulin; D016022:Case-Control Studies; D054370:Chemokine CXCL9; D019743:Chemokines, CXC / Q000235:genetics; D016000:Cluster Analysis; D003228:Conjunctiva / Q000378:metabolism*; D055233:Cornified Envelope Proline-Rich Proteins; D016002:Discriminant Analysis; D066255:EGF Family of Proteins; D004847:Epithelial Cells / Q000378:metabolism; D005240:Feasibility Studies; D005260:Female; D005353:Fibronectins / Q000235:genetics; D005786:Gene Expression Regulation; D016762:Genes, fos; D005819:Genetic Markers; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D007610:Kallikreins / Q000235:genetics; D007633:Keratins / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D011498:Protein Precursors / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D012859:Sjogren's Syndrome / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D023083:beta-Defensins / Q000235:genetics
C587848:AREG protein, human; D066258:Amphiregulin; C080810:CXCL9 protein, human; D054370:Chemokine CXCL9; D019743:Chemokines, CXC; D055233:Cornified Envelope Proline-Rich Proteins; D066255:EGF Family of Proteins; D005353:Fibronectins; D005819:Genetic Markers; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011498:Protein Precursors; D011506:Proteins; C101744:SPRR2A protein, human; D023083:beta-Defensins; D007633:Keratins; D007610:Kallikreins