Expression of CXCL8, CXCR1, and CXCR2 in neurons and glial cells of the human and rabbit retina.
OBJECTIVE
Several eye diseases are accompanied by inflammatory processes. The authors examined the expression of the proinflammatory chemokine CXCL8 and the corresponding receptors in healthy human retinas, in cellular membranes from patients with proliferative vitreoretinopathy (PVR) or human glial cell cultures and in an animal model of PVR in rabbit eyes.


METHODS
The authors used immunohistochemical methods, Western blotting, RT-PCR, and real time RT-PCR to characterize the expression of CXCL8, CXCR1, and CXCR2 in human and rabbit retinas. Functionality of the receptors in cultured glial cells was tested by Ca(2+) imaging.


RESULTS
Immunohistochemical examinations of normal human and rabbit retinas revealed a distinct expression of CXCR1 and CXCR2 in several neuronal cell types. CXCL8 mRNA was demonstrated only by RT-PCR in normal retinas, and receptor expression was confirmed by Western blotting and RT-PCR. The presence of CXCR1 and CXCR2, but not CXCL8, was detected by immunostaining in glial fibrillary acidic protein-positive glial cells of cellular PVR membranes. Immunoreactivity for CXCL8, CXCR1, and CXCR2 was observed in virtually all cultured glial cells and in the human Müller cell line MIO-M1. Müller cells responded to the application of CXCL8 with increased cytosolic Ca(2+) concentrations. In PVR rabbit retinas, CXCR1 expression is increased in Müller cells, and CXCL8 and CXCR2 are strongly expressed in microglial cells.


CONCLUSIONS
Expression of CXCL8 and CXCL8 receptors in glial cells of human PVR membranes and rabbit PVR retinas suggests an involvement in glial reactivity. Furthermore, the prominent expression of CXCR1 and CXCR2 in neurons of the healthy human and rabbit retina suggests additional physiological functions.
Paul-Flechsig-Institute for Brain Research, Interdisciplinary Centre for Clinical Research, Faculty of Medicine, University of Leipzig, Leipzig, Germany.
Iwona
I
Goczalik
Elke
E
Ulbricht
Margrit
M
Hollborn
Maik
M
Raap
Susann
S
Uhlmann
Michael
M
Weick
Thomas
T
Pannicke
Peter
P
Wiedemann
Andreas
A
Bringmann
Andreas
A
Reichenbach
Mike
M
Francke
D000818:Animals; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism; D004195:Disease Models, Animal; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D023062:Receptors, Interleukin-8A / Q000378:metabolism*; D023063:Receptors, Interleukin-8B / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism*
C508606:CXCL8 protein, human; D016209:Interleukin-8; D012333:RNA, Messenger; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B