Spatial proteomics revealed a CX3CL1-dependent crosstalk between the urothelium and relocated macrophages through IL-6 during an acute bacterial infection in the urinary bladder

Abstract

The urothelium of the urinary bladder represents the first line of defense. However, uropathogenic E. coli (UPEC) damage the urothelium and cause acute bacterial infection. Here, we demonstrate the crosstalk between macrophages and the urothelium stimulating macrophage migration into the urothelium. Using spatial proteomics by MALDI-MSI and LC-MS/MS, a novel algorithm revealed the spatial activation and migration of macrophages. Analysis of the spatial proteome unravelled the coexpression of Myo9b and F4/80 in the infected urothelium, indicating that macrophages have entered the urothelium upon infection. Immunofluorescence microscopy additionally indicated that intraurothelial macrophages phagocytosed UPEC and eliminated neutrophils. Further analysis of the spatial proteome by MALDI-MSI showed strong expression of IL-6 in the urothelium and local inhibition of this molecule reduced macrophage migration into the urothelium and aggravated the infection. After IL-6 inhibition, the expression of matrix metalloproteinases and chemokines, such as CX 3 CL1 was reduced in the urothelium. Accordingly, macrophage migration into the urothelium was diminished in the absence of CX 3 CL1 signaling in Cx 3 cr1 gfp/gfp mice. Conclusively, this study describes the crosstalk between the infected urothelium and macrophages through IL-6-induced CX 3 CL1 expression. Such crosstalk facilitates the relocation of macrophages into the urothelium and reduces bacterial burden in the urinary bladder.Mucosal Immunology (2020) 13:702-714; https://doi.

Regulation and function of CX3CR1 and its ligand CX3CL1 in kidney disease

“…In a more complex in vivo situation of bacterial cystitis, marked CX3CL1 upregulation was promoted by interleukin 6 in the murine bladder urothelium (Bottek et al 2020 ). This may have been directly mediated or induced via liberation of messengers from other cell types.…”

Tissue-resident macrophages mediate neutrophil recruitment and kidney injury in shiga toxin-induced hemolytic uremic syndrome

“…Sample preparation and analysis for liquid chromatography-tandem mass spectrometry Kidney sections were processed as previously described. 31 The liquid chromatography-tandem mass spectrometry data were acquired on an Ultimate 3000 RSLCnano system coupled online to an Orbitrap Elite mass spectrometer (both from Thermo Scientific).…”

Perspectives in systems nephrology

“…There are several studies that have employed urine proteomics for the non-invasive early detection of kidney disease (Bellei et al 2018 ). In the future, newly developed technologies such as spatial proteomics will allow us to obtain information of individual proteins on subcellular level and thus help us to better understand cell biology (Bottek et al 2020 ; Lundberg and Borner 2019 ).…”