Classification Systems in Renal Pathology: Promises and Problems

Integration of artificial intelligence and multi-omics in kidney diseases

Kidney disease is a leading cause of death worldwide. Currently, the diagnosis of kidney diseases and the grading of their severity are mainly based on clinical features, which do not reveal the underlying molecular pathways. More recent surge of ∼omics studies has greatly catalyzed disease research. The advent of artificial intelligence (AI) has opened the avenue for the efficient integration and interpretation of big datasets for discovering clinically actionable knowledge. This review discusses how AI and multi-omics can be applied and integrated, to offer opportunities to develop novel diagnostic and therapeutic means in kidney diseases. The combination of new technology and novel analysis pipelines can lead to breakthroughs in expanding our understanding of disease pathogenesis, shedding new light on biomarkers and disease classification, as well as providing possibilities of precise treatment.

Comparative analysis of hypertensive nephrosclerosis in animal models of hypertension and its relevance to human pathology. Glomerulopathy

Current research on hypertension utilizes more than fifty animal models that rely mainly on stable increases in systolic blood pressure. In experimental hypertension, grading or scoring of glomerulopathy in the majority of studies is based on a wide range of opinion-based histological changes that do not necessarily comply with lesional descriptors for glomerular injury that are well-established in clinical pathology. Here, we provide a critical appraisal of experimental hypertensive glomerulopathy with the same approach used to assess hypertensive glomerulopathy in humans. Four hypertensive models with varying pathogenesis were analyzed–chronic angiotensin II infused mice, mice expressing active human renin in the liver (TTRhRen), spontaneously hypertensive rats (SHR), and Goldblatt two-kidney one-clip rats (2K1C). Analysis of glomerulopathy utilized the same criteria applied in humans–hyalinosis, focal segmental glomerulosclerosis (FSGS), ischemic, hypertrophic and solidified glomeruli, or global glomerulosclerosis (GGS). Data from animal models were compared to human reference values. Kidneys in TTRhRen mice, SHR and the nonclipped kidneys in 2K1C rats had no sign of hyalinosis, FSGS or GGS. Glomerulopathy in these groups was limited to variations in mesangial and capillary compartment volumes, with mild increases in collagen deposition. Histopathology in angiotensin II infused mice corresponded to mesangioproliferative glomerulonephritis, but not hypertensive glomerulosclerosis. The number of nephrons was significantly reduced in TTRhRen mice and SHR, but did not correlate with severity of glomerulopathy. The most substantial human-like glomerulosclerotic lesions, including FSGS, ischemic obsolescent glomeruli and GGS, were found in the clipped kidneys of 2K1C rats. The comparison of affected kidneys to healthy control in animals produces lesion values that are numerically impressive but correspond to mild damage if compared to humans. Animal studies should be standardized by employing the criteria and classifications established in human pathology to make experimental and human data fully comparable for comprehensive analysis and model improvements.

Classification of Lupus Nephritis; Time for a Change?

Renal biopsy plays a critical role in the diagnosis and management of kidney disease in patients with systemic lupus erythematosus. The current pathologic classification of lupus nephritis is widely accepted but remains a work in progress. We discuss the key challenges in lupus nephritis classification and review new approaches to improve clinical utility and prognostic value.

Systematic review of the literature on reproducibility of the interpretation of renal biopsy in lupus nephritis

Objective Before using a test, it should be determined whether the results are reliable. The reliability of the interpretation of renal biopsy in patients with lupus nephritis has not been clearly elucidated. Our objective was to estimate inter and intra-observer reliability of the histological classification, as well as activity and chronicity indices in renal biopsy of patients with lupus nephritis. Methods We conducted a systematic search of the literature, which included articles in any language, using PubMed, Embase, Cochrane and Lilacs databases. Search terms included were: reproducibility, reliability, agreement, systemic lupus erythematosus and lupus nephritis. Comparative studies with any design were included, regardless of the year or the language of publication. Two investigators, independently, screened the literature published in accordance with pre-established inclusion and exclusion criteria. Results We found 13 relevant studies. Inter-observer reproducibility of most measurements was moderate or low, despite the fact that, in most cases, the readings were made by expert nephropathologists. There was great diversity among designs, participants, including samples and outcomes evaluated in different studies. Although there are too many reports on the clinical use, studies evaluating the reliability of classifications on renal biopsy in lupus nephritis are rare. The quality of the methodological design and reporting was fair. Conclusion The interpretation of renal biopsy in lupus nephritis is poorly reproducible, causing serious doubts about its validity and its clinical application. As it can lead to serious diagnosis, treatment and prognosis errors, it is necessary to intensify research in this field.