Podocytopathy

Glomerular diseases are important and a common group of renal disease in clinical practice. There are three main components of the glomerulus; mesangium, basement membrane and cells. Mesangial, endothelial and epithelial cells, both visceral and parietal, form the cellular component. Podocytes are highly differentiated visceral epithelial cells that wrap around the glomerular capillaries and are connected to the underlying basement membrane with inter-digitating foot processes. The rate of turnover of a podocyte is very slow and these also have a limited capability to proliferate. Primary functions of podocytes are capillary support, filtration barrier, glomerular basement synthesis and repair, cross-talk with other glomerular cells and some immunological function. Podocytes response to injury is also limited in the sense that either these deplete in number or hypertrophy or are subjected to epithelial-mesenchymal transformation (EMT).

This book is a compilation of articles related to podocytes in health and disease. Podocyte biology and its implication in relation to primary as well as secondary glomerular diseases, including genetic diseases has been the focus of intensive research in the field of nephrology in the last decade. This research has wide implications in terms of basic science (such as the structure of the extracellular membrane) and pharmacology (like identification of targetable kinases that function within these cells). This book discusses important aspects of podocyte structure and function and describes how advances in our understanding of these areas are increasing our knowledge of the pathogenesis of glomerular disease, enabling the identification of novel therapeutic targets. Chapters are appropriately grouped starting from podocyte biology to podocytes in primary and secondary glomerular diseases followed by podocytes as target for therapy and lastly new methods for studying podocytopathies.

Though the chapters and topics included are important, certain areas of nephrology related to podocyte injury are missing in the book. The authors could have included a chapter on biomarkers for podocyte injury and related issues. There are components of podocytes that can be identified in the urine of patients afflicted with glomerulopathies. These may serve as useful biomarkers, and as such this potentially may provide a number of possible routes of investigation. Another area which would have been useful for the readers is congenital and hereditary diseases such as diffuse mesangial sclerosis, congenital nephrotic syndrome and Alport's disease and many more. Also, missing is thrombotic microangiopathy and podocyte injury secondary to blockage of podocyte-derived vascular endothelial growth factor like in pre-eclampsia and drugs like bevacizumab, etc. Another area of glomerular diseases where the role of podocytes is important and a disease group which has serious clinical implications is collapsing glomerulopathy. Lastly, inflammatory glomerular diseases like systemic lupus erythematosus, IgA nephropathy and crescentic glomerulonephritis and their relation with podocytes are also missing. If the above mentioned areas were also included, this book would have been a complete compilation of podocyte knowledge for basic scientists as well as clinicians.

Chapters included are short with colourful diagrams and the flow of content is good for the reader to cover a large number of pages in a short time, even in topics involving molecular biology. Tables and pictures are appropriately chosen to explain the issues. Overall, this book will be useful for those nephrologists who wish to understand the recent advances and changing concepts of common proteinuric illness and glomerular diseases in relation to glomerular biology.