Renal collecting duct epithelial cells react to pyelonephritis-associated Escherichia coli by activating distinct TLR4-dependent and -independent inflammatory pathways.
TLR4 plays a central role in resistance to pyelonephritis caused by uropathogenic Escherichia coli (UPEC). It has been suggested that renal tubule epithelial cells expressing TLRs may play a key role in inflammatory disorders and in initiating host defenses. In this study we used an experimental mouse model of ascending urinary tract infection to show that UPEC isolates preferentially adhered to the apical surface of medullary collecting duct (MCD) intercalated cells. UPEC-infected C3H/HeJ (Lps(d)) mice carrying an inactivating mutation of tlr4 failed to clear renal bacteria and exhibited a dramatic slump in proinflammatory mediators as compared with infected wild-type C3H/HeOuJ (Lps(n)) mice. However, the level of expression of the leukocyte chemoattractants MIP-2 and TNF-alpha still remained greater in UPEC-infected than in naive C3H/HeJ (Lps(d)) mice. Using primary cultures of microdissected Lps(n) MCDs that expressed TLR4 and its accessory molecules MD2, MyD88, and CD14, we also show that UPECs stimulated both a TLR4-mediated, MyD88-dependent, TIR domain-containing adaptor-inducing IFN-beta-independent pathway and a TLR4-independent pathway, leading to bipolarized secretion of MIP-2. Stimulation by UPECs of the TLR4-mediated pathway in Lps(n) MCDs leads to the activation of NF-kappaB, and MAPK p38, ERK1/2, and JNK. In addition, UPECs stimulated TLR4-independent signaling by activating a TNF receptor-associated factor 2-apoptosis signal-regulatory kinase 1-JNK pathway. These findings demonstrate that epithelial collecting duct cells are actively involved in the initiation of an immune response via several distinct signaling pathways and suggest that intercalated cells play an active role in the recognition of UPECs colonizing the kidneys.
Chassin
Cécilia
C
INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon (CRB3), Unité de Formation et de Recherche de Médecine Xavier Bichat, 16 Rue Henri Huchard, F-75870 Paris Cedex 18, France.
Goujon
Jean-Michel
JM
Darche
Sylvie
S
du Merle
Laurence
L
Bens
Marcelle
M
Cluzeaud
Françoise
F
Werts
Catherine
C
Ogier-Denis
Eric
E
Le Bouguénec
Chantal
C
Buzoni-Gatel
Dominique
D
Vandewalle
Alain
A
D000818:Animals; D015153:Blotting, Western; D018925:Chemokines / Q000096:biosynthesis / Q000276:immunology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D004926:Escherichia coli / Q000276:immunology*; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007249:Inflammation / Q000276:immunology / Q000382:microbiology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000276:immunology / Q000382:microbiology*; D051379:Mice; D008817:Mice, Mutant Strains; D008855:Microscopy, Electron, Scanning; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011704:Pyelonephritis / Q000276:immunology* / Q000382:microbiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology* / Q000378:metabolism; D014552:Urinary Tract Infections / Q000150:complications
D018925:Chemokines; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D020928:Mitogen-Activated Protein Kinases