Intravital Multiphoton Imaging of Immune Cells

New Endothelial Mechanisms in Glomerular (Patho)biology and Proteinuria Development Captured by Intravital Multiphoton Imaging

Frontiers in Medicine ◽

10.3389/fmed.2021.765356 ◽

2021 ◽

Vol 8 ◽

Author(s):

Georgina Gyarmati ◽

Chaim O. Jacob ◽

János Peti-Peterdi

Keyword(s):

Immune Cells ◽

Multiphoton Microscopy ◽

Endothelial Injury ◽

Renal Diseases ◽

Primary Role ◽

Multiphoton Imaging ◽

Glomerular Diseases ◽

Glomerular Cell ◽

Podocyte Detachment

In the past two decades, intravital imaging using multiphoton microscopy has provided numerous new visual and mechanistic insights into glomerular biology and disease processes including the function of glomerular endothelial cells (GEnC), podocytes, and the development of proteinuria. Although glomerular endothelial injury is known to precede podocyte damage in several renal diseases, the primary role of GEnCs in proteinuria development received much less attention compared to the vast field of podocyte pathobiology. Consequently, our knowledge of GEnC mechanisms in glomerular diseases is still emerging. This review highlights new visual clues on molecular and cellular mechanisms of GEnCs and their crosstalk with podocytes and immune cells that were acquired recently by the application of multiphoton imaging of the intact glomerular microenvironment in various proteinuric disease models. New mechanisms of glomerular tissue remodeling and regeneration are discussed based on results of tracking the fate and function of individual GEnCs using serial intravital multiphoton imaging over several days and weeks. The three main topics of this review include (i) the role of endothelial injury and microthrombi in podocyte detachment and albumin leakage via hemodynamic and mechanical forces, (ii) the alterations of the endothelial surface layer (glycocalyx) and its interactions with circulating immune cells in lupus nephritis, and (iii) the structural and functional remodeling and regeneration of GEnCs in hypertension, diabetes, and other experimental injury conditions. By the comprehensive visual portrayal of GEnCs and the many other contributing glomerular cell types, this review emphasizes the complexity of pathogenic mechanisms that result in proteinuria development.

Download Full-text

Visualized macrophage dynamics and significance of S100A8 in obese fat

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1409480112 ◽

2015 ◽

Vol 112 (16) ◽

pp. E2058-E2066 ◽

Cited By ~ 30

Author(s):

Ryohei Sekimoto ◽

Shiro Fukuda ◽

Norikazu Maeda ◽

Yu Tsushima ◽

Keisuke Matsuda ◽

...

Keyword(s):

Adipose Tissue ◽

Immune Cells ◽

Microscopic Analysis ◽

Time Lapse ◽

Early Event ◽

Low Grade ◽

Multiphoton Imaging ◽

Inflammatory Processes

Chronic low-grade inflammation of adipose tissue plays a crucial role in the pathophysiology of obesity. Immunohistological microscopic analysis in obese fat tissue has demonstrated the infiltration of several immune cells such as macrophages, but dynamics of immune cells have not been fully elucidated and clarified. Here, by using intravital multiphoton imaging technique, to our knowledge for the first time, we analyzed and visualized the inflammatory processes in adipose tissue under high-fat and high-sucrose (HF/HS) diet with lysozyme M-EGFP transgenic (LysMEGFP) mice whose EGFP was specifically expressed in the myelomonocytic lineage. Mobility of LysMEGFP-positive macrophages was shown to be activated just 5 d after HF/HS diet, when the distinct hypertrophy of adipocytes and the accumulation of macrophages still have not become prominent. Significant increase of S100A8 was detected in mature adipocyte fraction just 5 d after HF/HS diet. Recombinant S100A8 protein stimulated chemotactic migration in vitro and in vivo, as well as induced proinflammatory molecules, both macrophages and adipocytes, such as TNF-α and chemokine (C-C motif) ligand 2. Finally, an antibody against S100A8 efficiently suppressed the HF/HS diet-induced initial inflammatory change, i.e., increased mobilization of adipose LysMEGFP-positive macrophages, and ameliorated HF/HS diet-induced insulin resistance. In conclusion, time-lapse intravital multiphoton imaging of adipose tissues identified the very early event exhibiting increased mobility of macrophages, which may be triggered by increased expression of adipose S100A8 and results in progression of chronic inflammation in situ.

Download Full-text