The five types of glomerulonephritis classified by pathogenesis, activity and chronicity (GN-AC)

Clinical and histological comparison of IgA nephritis and renal IgA vasculitis

BACKGROUND

Immunoglobulin A (IgA) nephritis (IgAN) and renal IgA vasculitis (IgAV) show renal IgA deposits, but whether these two diseases are distinct entities or a spectrum of the same condition is under debate. In this study, we add perspective by contrasting the clinical course and histological presentation using the Oxford classification and the National Institutes of Health lupus nephritis activity index (LN-AI) and chronicity index (LN-CI) in IgAN and IgAV.

METHODS

In this single-centre, retrospective study, kidney biopsies of 163 adult patients with IgAN and 60 adult patients with IgAV were compared according to the Oxford MEST-C score, LN-AI and LN-CI. At the time of biopsy, clinical presentation was compared in terms of age, arterial hypertension, diabetes mellitus, extrarenal manifestations, estimated glomerular filtration rate, proteinuria and urine sediment. IgAV patients and all IgAN patients with crescents received immunosuppressive treatment. After biopsy, kidney function was followed until patients reached end-stage renal disease (ESRD) or they died.

RESULTS

The clinical course and kidney histology differ in IgAN and IgAV. IgAV patients showed more microhaematuria and nephritic sediment, while IgAN patients had a greater history of arterial hypertension, more proteinuria and a higher risk for ESRD. These clinical differences were associated with histological differences, as kidney biopsies of IgAN patients were characterized by glomerulosclerosis and tubular atrophy while kidney biopsies of IgAV patients were characterized by endocapillary hypercellularity and crescents. Overall, tubular atrophy and an LN-CI ≥4 were associated with a higher risk for ESRD in IgAN and IgAV.

CONCLUSION

Our study supports the notion that IgAN and IgAV follow distinct courses, suggesting that they require different treatment strategies. Moreover, we make a point that the Oxford classification and LN-CI can be useful in categorizing and predicting long-term prognosis not only in IgAN, but also in IgAV.

GNCnn: A QuPath extension for glomerulosclerosis and glomerulonephritis characterization based on deep learning

The digitalization of traditional glass slide microscopy into whole slide images has opened up new opportunities for pathology, such as the application of artificial intelligence techniques. Specialized software is necessary to visualize and analyze these images. One of these applications is QuPath, a popular bioimage analysis tool. This study proposes GNCnn, the first open-source QuPath extension specifically designed for nephropathology. It integrates deep learning models to provide nephropathologists with an accessible, automatic detector and classifier of glomeruli, the basic filtering units of the kidneys. The aim is to offer nephropathologists a freely available application to measure and analyze glomeruli to identify conditions such as glomerulosclerosis and glomerulonephritis. GNCnn offers a user-friendly interface that enables nephropathologists to detect glomeruli with high accuracy (Dice coefficient of 0.807) and categorize them as either sclerotic or non-sclerotic, achieving a balanced accuracy of 98.46%. Furthermore, it facilitates the classification of non-sclerotic glomeruli into 12 commonly diagnosed types of glomerulonephritis, with a top-3 balanced accuracy of 84.41%. GNCnn provides real-time updates of results, which are available at both the glomerulus and slide levels. This allows users to complete a typical analysis task without leaving the main application, QuPath. This tool is the first to integrate the entire workflow for the assessment of glomerulonephritis directly into the nephropathologists' workspace, accelerating and supporting their diagnosis.

An Updated Comprehensive Review on Diseases Associated with Nephrotic Syndromes

There have been exciting advances in our knowledge of primary glomerular diseases and nephrotic syndromes in recent years. Beyond the histological pattern from renal biopsy, more precise phenotyping of the diseases and the use of modern nephrogenetics helps to improve treatment decisions and sometimes also avoid unnecessary exposure to potentially toxic immunosuppression. New biomarkers have led to easier and more accurate diagnoses and more targeted therapeutic decisions. The treatment landscape is becoming wider with a pipeline of promising new therapeutic agents with more sophisticated approaches. This review focuses on all aspects of entities that are associated with nephrotic syndromes with updated information on recent advances in each field. This includes podocytopathies (focal segmental glomerulosclerosis and minimal-change disease), membranous nephropathy, membranoproliferative glomerulonephritis, IgA nephropathy, fibrillary glomerulonephritis, amyloidosis, and monoclonal gammopathy of renal significance in the context of the nephrotic syndrome, but also renal involvement in systemic diseases, diabetic nephropathy, and drugs that are associated with nephrotic syndromes.

[State-of-the-art trends in the treatment of immune-mediated inflammatory kidney diseases: Translation of the fundamental science into clinical practice. A review]

Immune-mediated kidney diseases like glomerulonephritis and tubulointerstitial nephritis are not the most common cause of chronic kidney disease in the population, however the difficulties in their management, as well as a more rapid deterioration of kidney function, compared to diabetes mellitus and hypertension, justify the importance of this problem for internal medicine. Due to the fundamental discoveries in pathology and to the introduction of various methods of laboratory and instrumental investigation in the second half of the XX century substantial progress was made in the diagnostic approaches and treatment of these conditions. State-of-the-art diagnostic approach requires complex evaluation of the clinical, laboratory and morphological data to identify the nosological form of the disease. The accumulation of knowledge in the field of diseases' pathogenesis led to the revision of the current classification of glomerulonephritis that should be based on the immunopathogenesis of these conditions. The following phenotypes were suggested: autoimmunity-related, autoinflammation-related, alloimmunity-related, infections-related, and monoclonal gammopathy-related. The assessment of disease activity and chronicity in the kidney tissue should be mandatory. Personalized selection of the optimal treatment modality on the basis of the diagnosis, severity, and individual features of the patient is currently possible. The leading trends include rational prescription of glucocorticoids (steroid-sparing regimens) and cytotoxic agents, e.g. cyclophosphamide, as well as the introduction of multitarget regimens that include biologic agents or small molecules selectively suppressing B-cells or various complement pathways. Another mandatory component of treatment on par with immune suppression is nephroprotective therapy, which currently comprises not only traditional renin-angiotensin-aldosterone antagonists, but also endothelin receptor antagonists and sodium-glucose cotransporter-2 inhibitors. Current guidelines emphasize the importance of the non-pharmacological interventions for the implementation of the nephroprotective strategy. Rational combination of the aforementioned approaches allows for the optimization of the management of patients with immune-mediated kidney diseases, although it requires high competencies and strict adherence to the principles of the evidence-based medicine from the healthcare providers.