Cyclophosphamide-induced cystitis increases bladder CXCR4 expression and CXCR4-macrophage migration inhibitory factor association.
BACKGROUND
Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine involved in cystitis and a non-cognate ligand of the chemokine receptor CXCR4 in vitro. We studied whether CXCR4-MIF associations occur in rat bladder and the effect of experimental cystitis.


RESULTS
Twenty male rats received saline or cyclophosphamide (40 mg/kg; i.p.; every 3(rd) day) to induce persistent cystitis. After eight days, urine was collected and bladders excised under anesthesia. Bladder CXCR4 and CXCR4-MIF co-localization were examined with immunhistochemistry. ELISA determined MIF and stromal derived factor-1 (SDF-1; cognate ligand for CXCR4) levels. Bladder CXCR4 expression (real-time RTC-PCR) and protein levels (Western blotting) were examined. Co-immunoprecipitations studied MIF-CXCR4 associations.Urothelial basal and intermediate (but not superficial) cells in saline-treated rats contained CXCR4, co-localized with MIF. Cyclophosphamide treatment caused: 1) significant redistribution of CXCR4 immunostaining to all urothelial layers (especially apical surface of superficial cells) and increased bladder CXCR4 expression; 2) increased urine MIF with decreased bladder MIF; 3) increased bladder SDF-1; 4) increased CXCR4-MIF associations.


CONCLUSIONS
These data demonstrate CXCR4-MIF associations occur in vivo in rat bladder and increase in experimental cystitis. Thus, CXCR4 represents an alternative pathway for MIF-mediated signal transduction during bladder inflammation. In the bladder, MIF may compete with SDF-1 (cognate ligand) to activate signal transduction mediated by CXCR4.
Vera
Pedro L
PL
Bay Pines VA Healthcare System, Research & Development (151), Bay Pines, Florida, USA. pvera@health.usf.edu
Iczkowski
Kenneth A
KA
Wang
Xihai
X
Meyer-Siegler
Katherine L
KL
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000378:metabolism; D003520:Cyclophosphamide / Q000494:pharmacology; D003556:Cystitis / Q000139:chemically induced / Q000235:genetics*; D008263:Macrophage Migration-Inhibitory Factors / Q000378:metabolism* / Q000652:urine; D008297:Male; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D019718:Receptors, CXCR4 / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D001743:Urinary Bladder / Q000378:metabolism* / Q000473:pathology*; D019459:Urothelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D054377:Chemokine CXCL12; D008263:Macrophage Migration-Inhibitory Factors; D019718:Receptors, CXCR4; D012965:Sodium Chloride; D003520:Cyclophosphamide