Characterization of novel anti-cathepsin W antibodies and cellular distribution of cathepsin W in the gastrointestinal tract

Unveiling the Roles of Cysteine Proteinases F and W: From Structure to Pathological Implications and Therapeutic Targets

Cysteine cathepsins F and W are members of the papain-like cysteine protease family, which have distinct structural features and functional roles in various physiological and pathological processes. This review provides a comprehensive overview of the current understanding of the structure, biological functions, and pathological implications of cathepsins F and W. Beginning with an introduction to these proteases, we delve into their structural characteristics and elucidate their unique features that dictate their enzymatic activities and substrate specificity. We also explore the intricate involvement of cathepsins F and W in malignancies, highlighting their role as potential biomarkers and therapeutic targets in cancer progression. Furthermore, we discuss the emerging roles of these enzymes in immune response modulation and neurological disorders, shedding light on their implications in autoimmune and neurodegenerative diseases. Finally, we review the landscape of inhibitors targeting these proteases, highlighting their therapeutic potential and challenges in clinical translation. This review brings together the diverse facets of cysteine cathepsins F and W, providing insights into their roles in health and disease and guiding future investigations for therapeutic advances.

GRaNIE and GRaNPA: inference and evaluation of enhancer-mediated gene regulatory networks

Enhancers play a vital role in gene regulation and are critical in mediating the impact of noncoding genetic variants associated with complex traits. Enhancer activity is a cell-type-specific process regulated by transcription factors (TFs), epigenetic mechanisms and genetic variants. Despite the strong mechanistic link between TFs and enhancers, we currently lack a framework for jointly analysing them in cell-type-specific gene regulatory networks (GRN). Equally important, we lack an unbiased way of assessing the biological significance of inferred GRNs since no complete ground truth exists. To address these gaps, we present GRaNIE (Gene Regulatory Network Inference including Enhancers) and GRaNPA (Gene Regulatory Network Performance Analysis). GRaNIE (https://git.embl.de/grp-zaugg/GRaNIE) builds enhancer-mediated GRNs based on covariation of chromatin accessibility and RNA-seq across samples (e.g. individuals), while GRaNPA (https://git.embl.de/grp-zaugg/GRaNPA) assesses the performance of GRNs for predicting cell-type-specific differential expression. We demonstrate their power by investigating gene regulatory mechanisms underlying the response of macrophages to infection, cancer and common genetic traits including autoimmune diseases. Finally, our methods identify the TF PURA as a putative regulator of pro-inflammatory macrophage polarisation.

Cathepsins in oral diseases: mechanisms and therapeutic implications

Cathepsins are a type of lysosomal globulin hydrolase and are crucial for many physiological processes, including the resorption of bone matrix, innate immunity, apoptosis, proliferation, metastasis, autophagy, and angiogenesis. Findings regarding their functions in human physiological processes and disorders have drawn extensive attention. In this review, we will focus on the relationship between cathepsins and oral diseases. We highlight the structural and functional properties of cathepsins related to oral diseases, as well as the regulatory mechanisms in tissue and cells and their therapeutic uses. Elucidating the associated mechanism between cathepsins and oral diseases is thought to be a promising strategy for the treatment of oral diseases and may be a starting point for further studies at the molecular level.

The Multifaceted Role of the Lysosomal Protease Cathepsins in Kidney Disease

Kidney disease is worldwide the 12th leading cause of death affecting 8–16% of the entire population. Kidney disease encompasses acute (short-lasting episode) and chronic (developing over years) pathologies both leading to renal failure. Since specific treatments for acute or chronic kidney disease are limited, more than 2 million people a year require dialysis or kidney transplantation. Several recent evidences identified lysosomal proteases cathepsins as key players in kidney pathophysiology. Cathepsins, originally found in the lysosomes, exert important functions also in the cytosol and nucleus of cells as well as in the extracellular space, thus participating in a wide range of physiological and pathological processes. Based on their catalytic active site residue, the 15 human cathepsins identified up to now are classified in three different families: serine (cathepsins A and G), aspartate (cathepsins D and E), or cysteine (cathepsins B, C, F, H, K, L, O, S, V, X, and W) proteases. Specifically in the kidney, cathepsins B, D, L and S have been shown to regulate extracellular matrix homeostasis, autophagy, apoptosis, glomerular permeability, endothelial function, and inflammation. Dysregulation of their expression/activity has been associated to the onset and progression of kidney disease. This review summarizes most of the recent findings that highlight the critical role of cathepsins in kidney disease development and progression. A better understanding of the signaling pathways governed by cathepsins in kidney physiopathology may yield novel selective biomarkers or therapeutic targets for developing specific treatments against kidney disease.

Expression pattern of cathepsin W isoforms in peripheral blood and gastroesophageal mucosa of patients with gastroesophageal reflux disease

Cathepsin W is exclusively expressed in immune cells, and a novel isoform was identified previously. To characterize the expression pattern of the wildtype and isoform Ins10, specific polymerase chain reaction assays were generated and used to study respective transcript levels in peripheral blood cells and gastric biopsies in healthy subjects. The wildtype-encoding transcript levels were 3- and 9-fold higher in mucosal samples and peripheral immune cells, respectively (p<0.05). The predominant expression of wildtype form by infiltrating immune cells was confirmed in 116 patients with gastroesophageal reflux disease and 27 reflux-negative individuals demonstrating that cathepsin W expression is not altered in this disease.

Cathepsin W expressed exclusively in CD8+ T cells and NK cells, is secreted during target cell killing but is not essential for cytotoxicity in human CTLs

OBJECTIVE

Cathepsin W (CatW, lymphopain) is a putative cysteine protease with restricted expression to natural killer (NK) cells and CD8(+) T cells and so far unknown function and properties. Here, we characterize in detail, the regulation of human CatW during T-cell development in response to different stimuli and its functional involvement in cytotoxic lymphocyte effector function.

MATERIALS AND METHODS

Western blots and real time polymerase chain reaction of sorted, unstimulated, and stimulated cell subsets (thymocytes, T cells, NK cells) and their culture supernatants were used to study regulation and expression of CatW. Primary CD8(+) T cells and short-term T-cell lines were transfected with small interfering RNA to study the involvement of CatW in effector function such as target cell killing and interferon-gamma production.

RESULTS

Levels of CatW expression correlate closely with cytotoxic capacity both during development and in response to factors influencing cytotoxicity. Furthermore, CatW is secreted during specific target cell killing. However, knockdown of CatW expression by small interfering RNA neither influences target cell killing nor interferon-gamma production.

CONCLUSION

Despite being expressed in the effector subset of CD8(+) and NK cells and of being released during target cell killing, our functional inhibition studies exclude an essential role of CatW in the process of cytotoxicity.

Upregulation of cathepsin W-expressing T cells is specific for autoimmune atrophic gastritis compared to other types of chronic gastritis

AIM: To investigate a pathophysiological role of cathepsin W (CatW), a putative thiol-dependent cysteine protease, which is specifically expressed in cytotoxic lymphocytes, in different types of chronic inflammation of the gastric mucosa.

METHODS: Gastric and duodenal biopsies of patients with Helicobacter pylori (H pylori)-associated active gastritis (Hp, n = 19), chemically induced reactive gastritis (CG, n = 17), autoimmune atrophic gastritis (AIG, n = 20), lymphocytic corpus gastritis (LG, n = 29), celiac disease (CD, n = 10), and corresponding controls (n = 24) were analyzed by immunohistochemistry for the expression of CatW and CD45. Furthermore, immunohistochemical double staining with anti-CD3 and anti-cathepsin was performed for the samples of AIG.

RESULTS: Median values of CatW-expressing cells among CD45-positive immune cells were between 2% and 6% for normal gastric mucosa, CG, and LG, whereas the corresponding value was significantly increased for AIG (24.7%, P<0.001) and significantly decreased for HP (0.7%, P<0.05). Double staining with anti-CD3 and anti-CatW antibodies revealed that >90% of CatW-expressing cells in gastric mucosa of AIG were T cells. Duodenal mucosa had significantly more CatW/CD45-positive cells than normal gastric mucosa (median: 17.8% vs 2%, P<0.01). The corresponding proportion of CatW/CD45-positive cells was decreased in CD compared to duodenal mucosa (median: 2.1% vs 17.8%, P<0.05).

CONCLUSION: The opposite findings regarding the presence of CatW-positive cells in AIG (increase) and CD (decrease) reflects the different cellular composition of immune cells involved in the pathogenesis of these diseases.

Cathepsins K, L, B, X and W are differentially expressed in normal and chronically inflamed gastric mucosa

The expression of cathepsins K, L, B, X and W was studied by quantitative RT-PCR in normal and inflamed gastric mucosa (antrum, corpus, cardia). Cathepsins B, L, K and X were expressed ubiquitously. In contrast, cathepsin W was expressed at very low levels. Infection by Helicobacter pylori caused a significant induction of cathepsin X (p<0.008), whereas the other cathepsins were not or only locally affected by H. pylori infection or reflux disease. Immunohistochemistry revealed specific expression of cathepsin X (macrophages), cathepsin K (parietal cells) and cathepsin W (lymphocytes), whereas cathepsins B and L were predominantly expressed in epithelial cells.

Characterization of murine cathepsin W and its role in cell-mediated cytotoxicity

Cathepsin W is a member of the papain-like family of cysteine proteases. In this report, we have isolated the cDNA for murine CtsW (mCtsW) from a splenocyte library. The deduced 371-amino-acid sequence shares 68% identity with human CtsW and includes the conserved catalytic triad cysteine, histidine, and asparagine found in all members of this family. In addition to the fulllength form of mCtsW, we have isolated an alternatively spliced form of the mRNA that lacks a complete catalytic triad. An S1 nuclease protection assay and a Western blot analysis showed that mCtsW is mainly restricted to the CD8(+) T cell and natural killer cell compartments. In addition, we confirmed that, like its human homologue, mCtsW is localized mainly to the endoplasmic reticulum and its expression is up-regulated upon activation. We also characterized the mCtsW locus using bacterial artificial chromosome clones. The gene consists of 10 coding exons and 9 introns spanning 3.2 kb. To elucidate the physiologic role of this protease, we generated mice deficient in mCtsW. Our data establish that mCtsW is not required for cytotoxic lymphocyte-induced target cell death in vitro. In addition, mCtsW deficiency does not alter the susceptibility of cytotoxic lymphocytes to suicide or fratricide after degranulation. Thus, mCtsW does not have a unique role in target cell apoptosis or cytotoxic cell survival in vitro.

Functional involvement of cathepsin W in the cytotoxic activity of NK-92 cells

Human cathepsin W (lymphopain) is a papain-like cysteine protease of unknown function that is specifically expressed in natural killer (NK) cells and to a lesser extent in cytotoxic T cells (CTL). In order to analyze the functional importance of cathepsin W for the cytotoxic process, we investigated NK-92 cells that have an NK cell-like phenotype and express cathepsin W. NK-92 cells possess strong cytotoxic activity against Jurkat and K562 cells. The cytotoxic activity of NK-92 cells against K562 was decreased in the presence of antisense phosphorothioate oligonucleotides against the cathepsin W-cDNA. Western blot analysis showed that the impaired cytotoxic activity of NK-92 cells was accompanied by reduced amounts of cathepsin W in the antisense-treated cells. In addition, co-cultivation experiments between NK-92 and K562 cells revealed a time-dependent decrease of cathepsin W by Western blot and immunofluorescence analysis during the cytotoxic attack, whereas CD56 expression of NK-92 cells was not affected. During cytotoxic attack, cathepsin W was neither targeted to K562 cells or other subcellular compartments, as shown by immunofluorescence analysis. The decrease of cathepsin W protein was associated with stable cathepsin W transcript levels. Control experiments using HT-29 cells, which are resistant against NK-92-mediated cytotoxicity, showed no change of cathepsin W expression, implying that the decrease of cathepsin W in the NK-92/K562 assay is linked to the cytotoxic process. Although the exact function of cathepsin W with respect to its enzymatic activity and its site of action still needs to be elucidated, our data demonstrate for the first time that cathepsin W is important for cellular cytotoxicity mediated by NK cells.