Multiphoton imaging reveals a new leukocyte recruitment paradigm in the glomerulus

Abstract

In contrast with many capillary beds, the glomerulus readily supports leukocyte recruitment. However, little is known regarding the actions of leukocytes following their recruitment to glomeruli. We used multiphoton confocal microscopy to examine leukocyte behavior in the glomerular microvasculature. In normal glomeruli, neutrophils and monocytes were retained in capillaries for several minutes, remaining static or migrating intravascularly. Induction of glomerular inflammation resulted in an increase in the duration of retention of static and migratory leukocytes. In response to immune complex deposition, both static and migratory neutrophils generated oxidants in inflamed glomeruli via a Mac-1-dependent mechanism. Our results describe a new paradigm for glomerular inflammation, suggesting that the major effect of acute inflammation is to increase the duration of leukocyte retention in the glomerulus. Moreover, these findings describe a previously unknown form of multicellular intravascular patrolling that involves both monocytes and neutrophils, which may underlie the susceptibility of the glomerulus to inflammation.

Measuring and interpreting platelet-leukocyte aggregates

“…Neutrophil-depletion on the other hand prevented platelet accumulation within glomerular capillaries in a model of immune-complex-induced glomerulonephritis (22), emphasising the importance of the interplay between platelets and neutrophils during this disease. Indeed, our unpublished data suggest constitutive on/off interactions between platelets and neutrophils or monocytes in glomerular capillaries (Finsterbusch et al unpublished), leukocyte subsets that both were reported to contribute to renal injury in acute glomerular inflammation (116,117). …”

Renal Allograft Fibrosis: Biology and Therapeutic Targets

“…Although their regenerative potential is much higher than that of podocytes, chronic exposure of these cells to injurious stimuli in transplantation, for example, immunologic, hypertensive or toxic, likely contributes to glomerulosclerosis (113,114). In vivo imaging studies revealed a novel concept of glomerular inflammation in which leukocytes are retained on the glomerular endothelium for longer periods compared to other vascular beds but do not extravasate (115).…”

CX3CR1 Reduces Kidney Fibrosis by Inhibiting Local Proliferation of Profibrotic Macrophages

“…Mice were kept at 37˚C. Time lapse recordings of GFP + cells in the kidney of Cx 3 cr1 GFP/+ and Cx 3 cr1 GFP/GFP mice were captured using a Leica SP5 mulitphoton microscope system (Leica Microsystems, Mannheim, Germany) with a 320 1.0 NA water immersion objective (18,63). Fluorophores were excited by a SpectraPhysics MaiTai pulsed infrared laser tuned to 860 nm, with emissions captured by nondescanned detectors with 525/50 nm (GFP), 585/40 nm (tetramethylrhodamine isothiocyanate), and 650/50 nm (Alexa 633) filters.…”