Assessment of lysosomal function by quantitative histochemical and cytochemical methods

Immunohistochemistry and quantitative analysis of protein expression

CONTEXT

Immunohistochemistry has taken a central role in the field of pathology, and its role is destined to increase as companion diagnostics analogous to the HercepTest are required for new targeted therapeutics. However, the inherent subjectivity of the assessment of an objective value (the in situ protein concentration) suggests that new technologies to measure the protein concentration may be required to achieve the accuracy required for companion diagnostics.

OBJECTIVE

This article discusses the state of immunohistochemistry and reviews the currently available devices for quantitative in situ assessment of protein expression.

DATA SOURCES

Data for this work were collected from the published literature, the Internet, and from information provided by device vendors.

CONCLUSIONS

Although there is a long history of efforts to quantify immunohistochemistry, there has been a lack of broad acceptance because the resultant objective accuracy has not significantly improved outcome measures compared with the traditional, conventional analysis by eye. As the demand grows for companion diagnostics with complex assessment requirements, we are likely to see increased usage of quantitative platforms, especially those with the capacity to do multiplexed analysis. This most likely will be driven by a requirement for outcomes that cannot be achieved by traditional methods.

Quantitative immunohistochemistry of fluorescence labelled probes using low-cost software

This paper describes simple procedures to process digital images in quantitative immunofluorescence microscopy. Monoclonal antibodies directed against the sarcoplasmic myosin heavy chain isoforms and against laminin, located on the basement membranes, were applied to sections of human skeletal muscle. The localisation and staining intensity of a fluorescent secondary antibody were recorded using an indirect histochemical method. The digitised images were pre-processed and the luminosities of appropriate structures were determined using existing tools in the widely used image processing software Photoshop from Adobe. Procedures to obtain a quantitative measure for the specific fluorescence signal (the background corrected fluorescence in the object) were developed. In addition, antibody binding to individual cells could be quantified whether these cells are well separated or not. The relation between the specific fluorescence signal and the dilution factor of the primary antibody could be measured to determine a suitable concentration of the antibody for incubation of the sections. The potential fading of the fluorescence signal with time and prolonged exposure to light from the microscope was explored and analysed. With the tools described in the present report it is thus possible also to optimize the topical immunohistochemical protocol in order to quantify the fluorescence signal.

Neuronal death in newborn striatum after hypoxia-ischemia is necrosis and evolves with oxidative stress

The mechanisms for neurodegeneration after hypoxia-ischemia (HI) in newborns are not understood. We tested the hypothesis that striatal neuron death is necrosis and evolves with oxidative stress and selective organelle damage. Piglets ( approximately 1 week old) were used in a model of hypoxia-asphyxia and survived for 3, 6, 12, or 24 h. Neuronal death was progressive over 3-24 h recovery, with approximately 80% of putaminal neurons dead at 24 h. Striatal DNA was digested randomly at 6-12 h. Ultrastructurally, dying neurons were necrotic. Damage to the Golgi apparatus and rough endoplasmic reticulum occurred at 3-12 h, while most mitochondria appeared intact until 12 h. Mitochondria showed early suppression of activity, then a transient burst of activity at 6 h, followed by mitochondrial failure (determined by cytochrome c oxidase assay). Cytochrome c was depleted at 6 h after HI and thereafter. Damage to lysosomes occurred within 3-6 h. By 3 h recovery, glutathione levels were reduced, and peroxynitrite-mediated oxidative damage to membrane proteins, determined by immunoblots for nitrotyrosine, occurred at 3-12 h. The Golgi apparatus and cytoskeleton were early targets for extensive tyrosine nitration. Striatal neurons also sustained hydroxyl radical damage to DNA and RNA within 6 h after HI. We conclude that early glutathione depletion and oxidative stress between 3 and 6 h reperfusion promote damage to membrane and cytoskeletal proteins, DNA and RNA, as well as damage to most organelles, thereby causing neuronal necrosis in the striatum of newborns after HI.

Node-paranode regions as local degradative centres in alpha-motor axons

Lysosomes play an important role for the maintenance of a normal internal milieu in the cell. In neurons lysosomes are abundant in the perikaryon and dendrites, but have been observed to a much lesser degree in the axon. A general opinion has therefore formed among biologists interested in the nervous system that axonal material destined for degradation has to be transported to the neuronal perikaryon. The lysosomal occurrence and distribution at the level of the axon have, however, not been investigated systematically. This review summarizes recent morphological data based on light, fluorescence, and electron microscopic observations in peripheral nerve fibres of cats and rats providing evidence that node-paranode regions mainly along the peripheral parts of alpha motor axons, where the axon cross-section area decreases to 10-25% of internodal values, can control the passage and participate in a lysosome-mediated degradation of axonally transported materials directed towards the neuronal perikaryon. An important role is played by the paranodal axon-Schwann cell networks, which are lysosome-rich entities whereby the Schwann cells can sequester material from the axoplasm of large myelinated peripheral nerve fibres. The networks also seem to serve as depots for axonal waste products. The degradative ability of node-paranode regions in alpha-motor axons could be of some significance for the protection of the motor neuron perikarya from being flooded with and perhaps injured by indigestible materials as well as potentially deleterious, exogenous substances imbibed by the axon terminals in the muscle. A similar degradative capacity may not be needed in nerve fibres with synaptic terminals in the CNS where the local environment is regulated by the blood-brain barrier.

The Importance of Cytochemical Analysis of Alveolar Macrophages in the Evaluation of Their Biological Properties

Bronchoalveolar lavage (BAL) was performed in 48 subjects: 22 healthy controls, 13 patients with pulmonary sarcoidosis Stage I and 13 patients with lung cancer. All diagnoses were pathologically and clinically confirmed. Cytocentrifuge preparations were made, air-dried and stained for cytochemical examination of alveolar macrophages (AM) using indexing and scoring methods for the evaluation of esterase activity, intracellular amounts of glycogen, lipids and iron. Significant differences were found in the cytochemical examination of enzyme activity of AM and intracellular metabolic and ionic state, depending on pathological processes and smoking habits. There was a linear correlation between alpha naphthyl esterase activity and iron content in AM in patients with squamous cell lung carcinoma and in patients with pulmonary sarcoidosis, which makes it possible to assign individual patients to one of the groups. Cytochemical examination of BAL specimens might be of great significance for the prevention and early diagnosis of various malignant and non-malignant lung diseases.