Analysis of TNF-mediated recruitment and activation of glomerular dendritic cells in mouse kidneys by compartment-specific flow cytometry

Renal dendritic cells (DCs) form an interstitial network contributing to inflammatory and adaptive immune responses in the kidney. The presence and functional role of DC-like glomerular CD11c+ mononuclear phagocytes is a matter of debate. Using compartment-specific flow cytometry we found that healthy mouse kidneys contained 1.3 CD11c+ cells per 100 glomeruli and these increased by 4.6-fold and 13-fold after TNF stimulation and immune complex deposition, respectively. Compartment-specific mRNA expression revealed a predominantly glomerular expression of TNF receptors, chemokines, and adhesion molecules; all upregulated after TNF exposure. Intraperitoneal TNF injection induced influx of neutrophils and mononuclear phagocytes including DC-like CD11c+ cells into both the glomerular and tubulointerstitial compartments, but reduced in TNF receptor (Tnfr) 1-deficient mice. Additionally, Tnfr2 deficiency impaired glomerular infiltration of CD11c+ cells, but not neutrophils. Interstitial CD11c+ cells infiltrated in the presence of Tnfr1 or Tnfr2. TNF exposure also induced similar maturation of glomerular and interstitial CD11c+ cells as demonstrated by increased surface expression of MHC II, CD54, and costimulatory molecules CD40, CD80, and CD86. Thus, by compartment-specific flow cytometry we could demonstrate the constitutive presence of DC-like CD11c+ mononuclear phagocytes in normal mouse glomeruli and their TNF-induced accumulation and activation.