Lysosomal modifications in human proximal tubule induced by aminoglycoside treatment: visualisation by light microscopical cytochemistry

Mapping Adverse Outcome Pathways for Kidney Injury as a Basis for the Development of Mechanism-Based Animal-Sparing Approaches to Assessment of Nephrotoxicity

In line with recent OECD activities on the use of AOPs in developing Integrated Approaches to Testing and Assessment (IATAs), it is expected that systematic mapping of AOPs leading to systemic toxicity may provide a mechanistic framework for the development and implementation of mechanism-based in vitro endpoints. These may form part of an integrated testing strategy to reduce the need for repeated dose toxicity studies. Focusing on kidney and in particular the proximal tubule epithelium as a key target site of chemical-induced injury, the overall aim of this work is to contribute to building a network of AOPs leading to nephrotoxicity. Current mechanistic understanding of kidney injury initiated by 1) inhibition of mitochondrial DNA polymerase γ (mtDNA Polγ), 2) receptor mediated endocytosis and lysosomal overload, and 3) covalent protein binding, which all present fairly well established, common mechanisms by which certain chemicals or drugs may cause nephrotoxicity, is presented and systematically captured in a formal description of AOPs in line with the OECD AOP development programme and in accordance with the harmonized terminology provided by the Collaborative Adverse Outcome Pathway Wiki. The relative level of confidence in the established AOPs is assessed based on evolved Bradford-Hill weight of evidence considerations of biological plausibility, essentiality and empirical support (temporal and dose-response concordance).

Drug-induced lysosomal disorders in laboratory animals: new substances acting on lysosomes

Several substances with lysosomotropic activity were investigated in toxicological studies. AR-L 115 BS (sulmazol, a cardiotonic agent) was tested on beagle dogs; HX-CH 44 BS (a beta-blocker) and SX-AB 1316 SE (an antithrombotic agent) were tested on rats, and AF-CX 1325 XX (an antiepileptic agent) was tested on both rats and beagle dogs. All organ systems were examined morphologically by light and/or electron microscopy. When an increase in the number of lysosomes occurred this was confirmed by the pigment scheme according to Krutsay (1971) as well as by the detection of acid phosphatase and compared with earlier histochemical results. At higher dosages, all substances caused very marked proliferation of lysosomes in the liver and/or kidneys. HX-CH 44 BS also caused such proliferation in striated muscles and in the lungs. A brown discolouration of the kidneys was found with sulmazol and AF-CX 1325 XX. This finding corresponded to the microscopically detectable occurrence of numerous lipofuscin granules. The reticulum cells in the lymph nodes of dogs were also affected by AF-CX 1325 XX. It is concluded that the proliferation of lysosomes in various organs after administration of the above-mentioned substances is due to an excess of substance. The increased substance in the body is then stored in the lysosomes. With HX-CH 44 BS, lysosomal autodigestion of mitochondria in the skeletal musculature and in the alveolar macrophages of the lungs was found. The selective lysosomal incorporation of mitochondria has not been described up to now and in our opinion, this constitutes a special feature. The results otherwise largely correspond to those already described in the literature. Systemic phospholipidosis such as occurs with some other substances was not detectable. The incorporation of the substance causes several types of lysosomal inclusion. Uptake of the substance in lysosomes either leads to overt autodigestion of organelles such as mitochondria (HX-CH 44 BS) or peroxisomes or to residual lysosomes of dense structure which histochemically resemble lipofuscin. SX-AB 1316 SE serves as an example of a substance which is stored directly by lysosomes in crystalline form. Above all, in the liver the substance is taken up not only by the sinusoidal stellate cells but also by hepatocytes.

Use of laser microprobe mass analysis (LAMMA) for localizing multiple elements in soft and hard tissues

The potential of laser microprobe mass analysis (LAMMA) as a sensitive microanalytical technique was explored in applications relevant to nephrology. Aluminum and associated elements, such as iron, were localized in fresh tissue biopsies obtained from uremic patients treatment by chronic hemodialysis. The LAMMA was applied to serum, liver, bone, and parathyroid glands of such patients. In addition, we used LAMMA to evaluate the specificity and sensitivity of routine histochemistry, in particular on human bone sections stained by the aluminon method. The high, multielemental sensitivity and molecular microprobe potential of LAMMA established important advantages over other microchemical methods forin situ analysis at the micron level in histological sections.