Histochemical localization of sialic acids and antimicrobial substances in eccrine glands of porcine snout skin

Insulin granule morphology and crinosome formation in mice lacking the pancreatic β cell-specific phogrin (PTPRN2) gene

We recently reported that phogrin, also known as IA-2β or PTPRN2, forms a complex with the insulin receptor in pancreatic β cells upon glucose stimulation and stabilizes insulin receptor substrate 2. In β cells of systemic phogrin gene knockout (IA-2β-/-) mice, impaired glucose-induced insulin secretion, decreased insulin granule density, and an increase in the number and size of lysosomes have been reported. Since phogrin is expressed not only in β cells but also in various neuroendocrine cells, the precise impact of phogrin expressed in β cells on these cells remains unclear. In this study, we performed a comprehensive analysis of morphological changes in RIP-Cre+/-Phogrinflox/flox (βKO) mice with β cell-specific phogrin gene knockout. Compared to control RIP-Cre+/- Phogrin+/+ (Ctrl) mice, aged βKO mice exhibited a decreased density of insulin granules, which can be categorized into three subtypes. While no differences were observed in the density and size of lysosomes and crinosomes, organelles involved in insulin granule reduction, significant alterations in the regions of lysosomes responding positively to carbohydrate labeling were evident in young βKO mice. These alterations differed from those in Ctrl mice and continued to change with age. These electron microscopic findings suggest that phogrin expression in pancreatic β cells plays a role in insulin granule homeostasis and crinophagy during aging, potentially through insulin autocrine signaling and other mechanisms.

Exploration of the Sialic Acid World

Sialic acids are cytoprotectors, mainly localized on the surface of cell membranes with multiple and outstanding cell biological functions. The history of their structural analysis, occurrence, and functions is fascinating and described in this review. Reports from different researchers on apparently similar substances from a variety of biological materials led to the identification of a 9-carbon monosaccharide, which in 1957 was designated "sialic acid." The most frequently occurring member of the sialic acid family is N-acetylneuraminic acid, followed by N-glycolylneuraminic acid and O-acetylated derivatives, and up to now over about 80 neuraminic acid derivatives have been described. They appeared first in the animal kingdom, ranging from echinoderms up to higher animals, in many microorganisms, and are also expressed in insects, but are absent in higher plants. Sialic acids are masks and ligands and play as such dual roles in biology. Their involvement in immunology and tumor biology, as well as in hereditary diseases, cannot be underestimated. N-Glycolylneuraminic acid is very special, as this sugar cannot be expressed by humans, but is a xenoantigen with pathogenetic potential. Sialidases (neuraminidases), which liberate sialic acids from cellular compounds, had been known from very early on from studies with influenza viruses. Sialyltransferases, which are responsible for the sialylation of glycans and elongation of polysialic acids, are studied because of their significance in development and, for instance, in cancer. As more information about the functions in health and disease is acquired, the use of sialic acids in the treatment of diseases is also envisaged.

Ultrastructure and immunohistochemical characterization of proteins concerned with the secretory machinery in goat ceruminous glands

The expression of soluble N-ethylmaleimide sensitive fusion attachment protein receptor (SNARE) proteins in apocrine glands has not been fully elucidated. In addition to performing ultrastructural observation of the ceruminous glands in goats, our study focuses on the demonstration of β-defensins, SNARE proteins and Rab3D in these glands with the use of immunohistochemical methods. The secretory cells were equipped with two types of vesicles, Golgi apparatus and abundant rough endoplasmic reticulum (ER). Additionally, in some of them, the characteristic concentric structures composed of rough ER were observed in their circum- and infranuclear parts. The expression of phosphorylated inositol requiring enzyme 1rrwas also detected. These findings may indicate their ability to produce numerous secretory proteins and the maintenance of homeostasis in the glandular cells. Furthermore, β-defensins were demonstrated as products of the ceruminous glands. The present investigation also revealed the presence of SNARE proteins and Rab3D. It is suggested that these proteins are concerned with the secretory machinery of this gland type.

Degranulation and shrinkage of dark cells in eccrine glands and elevated serum carcinoembryonic antigen in patients with acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) is characterized by anhidrosis/hypohidrosis without other autonomic and neurological dysfunctions. Pathologically, AIGA is considered to usually present no significant morphological alterations in eccrine glands, the secretory portion which consists of clear cells, dark cells, and myoepithelial cells. AIGA patients recently have been reported to show high serum concentrations of carcinoembryonic antigen (CEA).

OBJECTIVE

Our aim is to reveal morphological abnormalities of dark cells and investigate their relationship with serum CEA.

METHODS

We performed comparative analysis of eccrine glands between sweat-preserved and non-sweating skin in four AIGA patients. Serum CEA concentrations in 22 cases with AIGA were measured with healthy volunteers. Furthermore, we semiquantitatively investigated dermcidin, FoxA1 and CEA expression in eccrine glands of 12 cases with AIGA and 5 cases with non-AIGA.

RESULTS

Marked degranulation and shrinkage of dark cells consistently occurred in AIGA. Furthermore, high serum CEA concentrations were found in 14 of 22 AIGA patients (over 60%), but serum CEA levels were not correlated with CEA expression in eccrine glands. Dermcidin expression in dark cells apparently decreased in AIGA patients, severely in those with high serum CEA and moderately in those with low serum CEA, while well-preserved expression was found in non-AIGA subjects.

CONCLUSION

Our study suggests morphological damage and molecular dysregulation of dark cells, leading to impairment of their functions in AIGA patients. Severely damaged dark cells correspond to high serum CEA. Accordingly, these pathological changes in eccrine dark cells may be involved in anhidrosis/hypohidrosis of AIGA.

Cytochemistry of sialoglycoconjugates and lysozyme in canine anal glands as studied by electron microscopic methods

The distribution of sialoglycoconjugates and lysozyme in the secretory cells of canine anal glands was studied by means of electron microscopic cytochemical methods, particularly lectin cytochemistry and immunocytochemistry. Sialic acids were predominantly present in the secretory granules, Golgi bodies, surface coat of the plasma membrane and luminal secretions. In addition, within these structures, the secretory granules, Golgi bodies and luminal secretions exhibited high levels of sialoglycoconjugates that terminated in Siaα2-6Gal/GalNAc or Siaα2-3Galβ1-4GlcNAc. In the secretory cells, reactive gold particles representing lysozyme were mainly detectable in the secretory granules and Golgi bodies. Sialic acids possess diverging functional properties, whereas lysozyme contributes to the non-specific defense against microorganisms. Therefore, their presence and secretion are suggestive of protective effects of both secretory products at the anal mucosa.

On the future contents of a small journal of histochemistry

In the last three years, more than 70,000 scientific articles have been published in peer reviewed journals on the application of histochemistry in the biomedical field: most of them did not appear in strictly histochemical journals, but in others dealing with cell and molecular biology, medicine or biotechnology. This proves that histochemistry is still an active and innovative discipline with relevance in basic and applied biological research, but also demonstrates that especially the small histochemical journals should likely reconsider their scopes and strategies to preserve their authorship. A review of the last three years volumes of the European Journal of Histochemistry, taken as an example of a long-time established small journal, confirmed that the published articles were widely heterogeneous in their topics and experimental models, as in this journal's tradition. This strongly suggests that a journal of histochemistry should keep its role as a forum open to an audience as broad as possible, publishing papers on cell and tissue biology in a wide variety of models. This will improve knowledge of the basic mechanisms of development and differentiation, while helping to increase the number of potential authors since scientists who generally do not use histochemistry in their research will find hints for the applications of histochemical techniques to novel still unexplored subjects.

Cytochemistry of sialoglycoconjugates, lysozyme, and β-defensin in eccrine glands of porcine snout skin as studied by electron microscopy

In most mammals except for humanoid primates, eccrine glands are confined to the skin of a series of specific body regions. Sialic acids and antimicrobial substances exhibit various functional properties and serve as a component of nonspecific defense against micro-organisms, respectively. In this study, the distribution of these moieties was studied by electron microscopic histochemical methods. The eccrine glandular acini consisted of two types of dark cells as well as clear cells. The secretory granules and Golgi apparatus of both types of dark cells contained sialic acid residues linked to α2-6Gal/GalNAc. On the other hand, sialoglycoconjugates with Siα2-3Galβ1-4GlcNAc sequence were confined to those of the Type II dark cells. In addition, lysozyme and β-defensin were mainly detected in the secretory granules of the Type II dark cells. These secretory products may create a defensive barrier against microbial invasion and play an essential role in preservation of the integrity of porcine snout skin as a sensory organ.