Immunocytochemical localization of cathepsins B, H, and L in the rat gastro-duodenal mucosa

Abstract

Cathepsins B, H, and L are representative cysteine proteinases in lysosomes of a large variety of cells. Previous immunochemical studies indicated the presence of these enzymes also in the gastrointestinal wall. Using specific antisera, the cellular and subcellular distribution of cathepsins B, H, and L in rat gastric (oxyntic and pyloric part) and duodenal mucosa was investigated by light and electron microscopical immunocytochemistry. The subtypes of cathepsins were distributed differently in the cellular constituents of the epithelia: Cathepsin B was localized to lysosomes of all cells except goblet cells. Cathepsin H was found predominantly in gastric parietal cells (lysosomes) and in secretion granules of pyloric gastrin and duodenal cholecystokinin cells. Cathepsin L immunoreactivities were weak and restricted to a minority of cells (gastric mucous cells, enterocytes). Interstitial cells of the lamina propria immunoreactive for cathepsins H and L were identified as macrophages. The present findings suggest a dual function of cathepsins in the gastro-duodenal mucosa. They (1) cleave enzymatically proteins and peptides ingested in lysosomes, and (2) they may be involved in the processing of biologically active peptides (enteric hormones) from their precursor proteins.

Intestinal epithelial cells use two distinct pathways for HLA class II antigen processing.

“…The expression of cysteine proteases (cathepsins B, L, and H) has been described in the mucosa of the gastrointestinal tract, and these enzymes were histochemically localized to enterocytes of the rat duodenum (33). We performed an analysis of both the cysteine and aspartyl-protease activity in our human IEC lines.…”

Different Distribution Patterns of the Two Mannose 6-phosphate Receptors in Rat Liver

“…It has also been shown that cathepsin L is localized in Kupffer cells of the liver and macrophages in the lung and intestine (Ii et al 1985;Watanabe et al 1989;Furuhashi et al 1991;Ishii et al 1991). The present results, using ISH, confirmed that cathepsin L mRNA was specifically detected in Kupffer cells.…”

Cell and Tissue Distribution of Lysosomal Cysteine Proteinases, Cathepsins B, H, and L, and their Biological Roles.

“…In the liver, cathepsins B and H are localized in lysosomes of both hepatocytes and Kupffer cells, while cathepsin L is more intensely detected in Kupffer cells than in hepatocytes (27). Interestingly, duodenal epithelial cells contain lysosomes immunopositive for cathepsins B and L, but not for cathepsin H, which is intensely localized in lysosomes of macrophages in the lamina propria (24). It is well known that the epididymal ducts are divided into several segments that differ functionally as well as morphologically (6).…”

“…Takahashi et al (79) have shown that cathepsin B activates prorenin into active renin. In fact, cathepsin B or H has been demonstrated to be localized in secretory granules of some peptidehormone producing cells including those producing active renin (24,28,52,69,92,93,101,102,112), suggesting that cathepsins B and H may participate in the activation processes of bioactive proteins and peptide hormones. Therefore, it is also important to examine the roles of the cysteine proteinases in the extralysosomal compartments of the cells.…”

“…Using immunohisto/cytochemical techniques, the localization of these enzymes have been precisely examined in the kidney (81,113), liver (27,105,111), pancreatic islets (108), heart (112), lung (31,32), thyroid gland (101,102), pituitary gland (92,93), gastro-intestine (24), parathyroid gland (26), submandibular gland (69), central nervous system (CNS) (7-10, 80), bone (68), and epididymis (82 (32,100,105). In rat liver, immunodeposits for cathepsins B and H are localized in hepatocytes and Kupffer cells (Fig.…”