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

Cathepsin W restrains peripheral regulatory T cells for mucosal immune quiescence

Peripheral regulatory T (pT_reg) cells are a key T cell lineage for mucosal immune tolerance and anti-inflammatory responses, and interleukin-2 receptor (IL-2R) signaling is critical for T_reg cell generation, expansion, and maintenance. The expression of IL-2R on pT_reg cells is tightly regulated to ensure proper induction and function of pT_reg cells without a clear molecular mechanism. We here demonstrate that Cathepsin W (CTSW), a cysteine proteinase highly induced in pT_reg cells under transforming growth factor-β stimulation is essential for the restraint of pT_reg cell differentiation in an intrinsic manner. Loss of CTSW results in elevated pT_reg cell generation, protecting the animals from intestinal inflammation. Mechanistically, CTSW inhibits IL-2R signaling in pT_reg cells by cytosolic interaction with and process of CD25, repressing signal transducer and activator of transcription 5 activation to restrain pT_reg cell generation and maintenance. Hence, our data indicate that CTSW acts as a gatekeeper to calibrate pT_reg cell differentiation and function for mucosal immune quiescence.

Cathepsin K: A Versatile Potential Biomarker and Therapeutic Target for Various Cancers

Cancer, a common malignant disease, is one of the predominant causes of diseases that lead to death. Additionally, cancer is often detected in advanced stages and cannot be radically cured. Consequently, there is an urgent need for reliable and easily detectable markers to identify and monitor cancer onset and progression as early as possible. Our aim was to systematically review the relevant roles of cathepsin K (CTSK) in various possible cancers in existing studies. CTSK, a well-known key enzyme in the bone resorption process and most studied for its roles in the effective degradation of the bone extracellular matrix, is expressed in various organs. Nowadays, CTSK has been involved in various cancers such as prostate cancer, breast cancer, bone cancer, renal carcinoma, lung cancer and other cancers. In addition, CTSK can promote tumor cells proliferation, invasion and migration, and its mechanism may be related to RANK/RANKL, TGF-β, mTOR and the Wnt/β-catenin signaling pathway. Clinically, some progress has been made with the use of cathepsin K inhibitors in the treatment of certain cancers. This paper reviewed our current understanding of the possible roles of CTSK in various cancers and discussed its potential as a biomarker and/or novel molecular target for various cancers.

Helicobacter pylori and gastric cancer: a lysosomal protease perspective

The intimate involvement of pathogens with the heightened risk for developing certain cancers is an area of research that has captured a great deal of attention over the last 10 years. One firmly established paradigm that highlights this aspect of disease progression is in the instance of Helicobacter pylori infection and the contribution it makes in elevating the risk for developing gastric cancer. Whilst the molecular mechanisms that pinpoint the contribution that this microorganism inflicts towards host cells during gastric cancer initiation have come into greater focus, another picture that has also emerged is one that implicates the host's immune system, and the chronic inflammation that can arise therefrom, as being a central contributory factor in disease progression. Consequently, when taken with the underlying role that the extracellular matrix plays in the development of most cancers, and how this dynamic can be modulated by proteases expressed from the tumor or inflammatory cells, a complex and detailed relationship shared between the individual cellular components and their surroundings is coming into focus. In this review article, we draw attention to the emerging role played by the cathepsin proteases in modulating the stage-specific progression of Helicobacter pylori-initiated gastric cancer and the underlying immune response, while highlighting the therapeutic significance of this dynamic and how it may be amenable for novel intervention strategies within a basic research or clinical setting.

Cronobacter sakazakii ATCC 29544 Translocated Human Brain Microvascular Endothelial Cells via Endocytosis, Apoptosis Induction, and Disruption of Tight Junction

Cronobacter sakazakii (C. sakazakii) is an emerging opportunistic foodborne pathogen that can cause neonatal necrotizing enterocolitis, meningitis, sepsis in neonates and infants with a relatively high mortality rate. Bacterial transcytosis across the human brain microvascular endothelial cells (HBMEC) is vital for C. sakazakii to induce neonatal meningitis. However, few studies focus on the mechanisms by which C. sakazakii translocates HBMEC. In this study, the translocation processes of C. sakazakii on HBMEC were explored. C. sakazakii strains could effectively adhere to, invade and intracellularly survive in HBMEC. The strain ATCC 29544 exhibited the highest translocation efficiency across HBMEC monolayer among four tested strains. Bacteria-contained intracellular endosomes were detected in C. sakazakii-infected HBMEC by a transmission electron microscope. Endocytosis-related proteins CD44, Rab5, Rab7, and LAMP2 were increased after infection, while the level of Cathepsin L did not change. C. sakazakii induced TLR4/NF-κB inflammatory signal pathway activation in HBMEC, with increased NO production and elevated mRNA levels of IL-8, IL-6, TNF-α, IL-1β, iNOS, and COX-2. C. sakazakii infection also caused LDH release, caspase-3 activation, and HBMEC apoptosis. Meanwhile, increased Dextran-FITC permeability and decreased trans epithelial electric resistance indicated that C. sakazakii disrupted tight junction of HBMEC monolayers, which was confirmed by the decreased levels of tight junction-related proteins ZO-1 and Occludin. These findings suggest that C. sakazakii induced intracellular bacterial endocytosis, stimulated inflammation and apoptosis, disrupted monolayer tight junction in HBMEC, which all together contribute to bacterial translocation.

Cathepsins in the Pathophysiology of Mucopolysaccharidoses: New Perspectives for Therapy

Cathepsins (CTSs) are ubiquitously expressed proteases normally found in the endolysosomal compartment where they mediate protein degradation and turnover. However, CTSs are also found in the cytoplasm, nucleus, and extracellular matrix where they actively participate in cell signaling, protein processing, and trafficking through the plasma and nuclear membranes and between intracellular organelles. Dysregulation in CTS expression and/or activity disrupts cellular homeostasis, thus contributing to many human diseases, including inflammatory and cardiovascular diseases, neurodegenerative disorders, diabetes, obesity, cancer, kidney dysfunction, and others. This review aimed to highlight the involvement of CTSs in inherited lysosomal storage disorders, with a primary focus to the emerging evidence on the role of CTSs in the pathophysiology of Mucopolysaccharidoses (MPSs). These latter diseases are characterized by severe neurological, skeletal and cardiovascular phenotypes, and no effective cure exists to date. The advance in the knowledge of the molecular mechanisms underlying the activity of CTSs in MPSs may open a new challenge for the development of novel therapeutic approaches for the cure of such intractable diseases.

Helicobacter pylori vs immune system or antibiotics

Helicobacter pylori (H. pylori) infection has often no clinical signs and is one of the most common bacterial infections. All infected subjects have histology of active chronic gastritis. In some cases patients develop peptic ulcer and minority of them develop gastric cancer. Gastric cancer is multifactorial disease, thus various progressions of H. pylori infection and disease are dependent on the host genetic factors, the characteristics of the individual’s immune response, environmental factors, and different bacterial virulence factors of the individual bacterial strains. Eradication of the bacteria plays a crucial role in the treatment of these cases however antibiotic therapy does not always help. Bacteria often develop resistance to antibiotics so we recommend that not only screening for H. pylori also the strain determination should have some diagnostic value, especially in the patients who already developed gastritis. Furthermore, for such patients assessment of disease progression (atrophic or metaplastic gastritis) could be followed by polymorphism determination. Until now we cannot predict the disease based only on single polymorphism. Bacteria successfully neutralize the responses of the immune systems using different enzymes or even components of the host immune response. However, the influence of immune system and its components could represent new ways of treatments and could help to eradicate the infection.

Dysregulation of apoptotic signaling pathways by interaction of RPLP0 and cathepsin X/Z in gastric cancer

Cathepsin X (CTSX, also called cathepsin Z/P) is a cysteine protease that still plays an unknown role in human cancer. It has been shown to bind cell surface heparin sulphate proteoglycans and integrins, indicating possible functions of CTSX in cellular adhesion, phagocytosis, and immune response. Our previous studies have shown an association between Helicobacter pylori (H. pylori) infection, a strong up-regulation of CTSX, and development of gastric cancer. In this study, yeast two-hybrid analysis revealed that RPLP0, a ribosomal protein P0, interacts with the human CTSX protein in gastric cancer. The CTSX/RPLP0 interaction was confirmed by co-immunoprecipitation assays. In addition, co-localization studies in cancer cell line N87 and gastric cancer tissue samples were performed. Laserscan microscopy revealed a shuttling of RPLP0 (and CTSX) from cytoplasm to the nucleus after CTSX knockdown. Down-regulation of RPLP0 resulted in G1 arrest of gastric cancer cells, whereas knockdown of CTSX led to G1 arrest and apoptosis after 48 h. Knockdown of both proteins caused increased apoptosis. RPLP0 deficiency could suppress cell growth and cell cycle progression by down-regulating CDK2. It was further demonstrated that RPLP0 affected p21 expression, but did not change the expression of Cyclin E. Down-regulation of both proteins at least through CDK2 suggests an anti-apoptotic effect on gastric cancer cells and opens up new possibilities for apoptotic immune modulation and gastric cancer therapy.

Characterization of cathepsin X in colorectal cancer development and progression

The lysosomal cysteine carboxypeptidase cathepsin X (CTSX), localized predominantly in immune cells, has been associated with the development and progression of cancer. To determine its specific role in colorectal carcinoma (CRC), we analyzed CTSX expression in non-malignant mucosa and carcinoma of 177 patients as well as in 111 adenomas and related it with clinicopathological parameters. Further, the role of CTSX in the adhesion and invasion of the colon carcinoma cell lines HT-29 and HCT116 was investigated in an in vitro culture cell system with fibroblasts and monocytes, reflecting the situation at the tumor invasion front. Epithelial CTSX expression significantly increased from normal mucosa to adenoma and carcinoma, with highest expression levels in high grade intraepithelial neoplasia and in early tumor stages. Loss of CTSX occurred with tumor progression, and correlated with advanced local invasion, lymph node and distal metastasis, lymphatic vessel and vein invasion, tumor cell budding and poorer overall survival of patients with CRC. The subcellular distribution of CTSX changed from vesicular paranuclear expression in the tumor center to submembranous expression in cells of the invasion front. Peritumoral macrophages showed highest expression of CTSX. In vitro assays identified CTSX as relevant factor for cell-cell adhesion and tumor cell anchorage to fibroblasts and basal membrane components, whereas inhibition of CTSX caused increased invasiveness of colon carcinoma cells in mono- and co-culture. In conclusion, CTSX is involved in early tumorigenesis and in the stabilization of tumor cell formation in CRC. The results suggest that loss of CTSX may be needed for tumor cell detachment, local invasion and tumor progression. In addition, CTSX in tumor-associated macrophages indicates a role for CTSX in the anti-tumor immune response.

Differences in the antigens of Helicobacter pylori strains influence on the innate immune response in the in vitro experiments

The immune response to Helicobacter pylori importantly determines the pathogenesis of infection as well as the success of antibiotic eradication of the bacteria. Strains of H. pylori were gathered from 14 patients who failed to eradicate H. pylori infection with antibiotics—therapy resistant strains (TRS)—or from patients who were able to eradicate H. pylori infection—therapy susceptible strains (TSS). The THP-1 cells were stimulated with H. pylori antigens. Cathepsin X expression on THP-1 cells and concentration of cytokines in the supernatant of THP-1 cells were measured with a flow cytometer. TSS H. pylori antigens increased the proportion of cathepsin X positive cells compared to TRS H. pylori antigens. TSS H. pylori antigens induced higher secretion of IL-12 and IL-6 compared to TRS H. pylori antigens (P < 0.001; 0.02). Polymyxin B, a lipid A inhibitor, lowered the secretion of IL-12 and IL-6 in TRS and TSS. We demonstrated a H. pylori strain-dependent cathepsin X and cytokine expression that can be associated with H. pylori resistance to eradication due to lack of effective immune response. Differences in lipid A of H. pylori might have an influence on the insufficient immune response, especially on phagocytosis.

Inhibition of cathepsin X enzyme influences the immune response of THP-1 cells and dendritic cells infected with Helicobacter pylori

Background

The immune response to Helicobacter pylori importantly determines the outcome of infection as well as the success of eradication therapy. We demonstrate the role of a cysteine protease cathepsin X in the immune response to H. pylori infection.

Materials and methods

We analysed how the inhibition of cathepsin X influenced the immune response in experiments when THP-1 cells or dendritic cells isolated from patients were stimulated with 48 strains of H. pylori isolated from gastric biopsy samples of patients which had problems with the eradication of bacteria.

Results

The experiments, performed with the help of a flow cytometer, showed that the expression of Toll-like receptors (TLRs), especially TLR-4 molecules, on the membranes of THP-1 cells or dendritic cells was higher when we stimulated cells with H. pylori together with inhibitor of cathepsin X 2F12 compared to THP-1 cells or dendritic cells stimulated with H. pylori only, and also in comparison with negative control samples. We also demonstrated that when we inhibited the action of cathepsin X in THP-1 cells, the concentrations of pro-inflammatory cytokines were lower than when THP-1 cell were stimulated with H. pylori only.

Conclusions

We demonstrated that inhibition of cathepsin X influences the internalization of TLR-2 and TLR-4. TLR-2 and TLR-4 redistribution to intra-cytoplasmic compartments is hampered if cathepsin X is blocked. The beginning of a successful immune response against H. pylori in the case of inhibition of cathepsin X is delayed.

Induction of premalignant host responses by cathepsin x/z-deficiency in Helicobacter pylori-infected mice

Helicobacter pylori are responsible for the induction of chronic gastric inflammation progressing to atrophy, metaplasia, and gastric cancer. The overexpression of Cathepsin X/Z (Ctsz) in H. pylori-infected mucosa and gastric cancer is mediated predominantly by an augmented migration of ctsz^−/−positive macrophages and the up-regulation of Ctsz in tumor epithelium. To explore the Ctsz-function in the context of chronic inflammation and the development of preneoplastic lesions, we used Ctsz-deficient mice in a H. pylori gastritis model. Ctsz^−/− and wild-type (wt) mice were infected with H. pylori strain SS1. The mice were sacrificed at 24, 36, and 50 weeks post infection (wpi). The stomach was removed, and gastric strips were snap-frozen or embedded and stained with H&E. Tissue sections were scored for epithelial lesions and inflammation. Ki-67 and F4/80 immunostaining were used to measure epithelial cell proliferation and macrophage infiltration, respectively. The upregulation of compensating cathepsins and cytokines were confirmed by Western blotting and quantitative RT-PCR. SS1-infected wt and ctsz^−/− mice showed strong inflammation, foveolar hyperplasia, atrophy, and cystically-dilated glands. However, at 50 wpi, ctsz^−/− mice developed significantly more severe spasmolytic polypeptide-expressing metaplasia (SPEM), showed enhanced epithelial proliferation, and higher levels of infiltrating macrophages. Induction of cytokines was higher and significantly prolonged in ctsz^−/− mice compared to wt. Ctsz deficiency supports H. pylori-dependent development of chronic gastritis up to metaplasia, indicating a protective, but not proteolytic, function of Ctsz in inflammatory gastric disease.

Serum proteome profiling of pancreatitis using recombinant antibody microarrays reveals disease-associated biomarker signatures

PURPOSE

Pancreatitis is an inflammatory state of the pancreas, for which high-performing serological biomarkers are lacking. The aim of the present study was to evaluate the use of affinity proteomics for identifying potential markers of disease and stratifying pancreatitis subtypes.

EXPERIMENTAL DESIGN

High-content, recombinant antibody microarrays were applied for serum protein expression profiling of 113 serum samples from patients with chronic, acute, and autoimmune pancreatitis, as well as healthy controls. The sample groups were compared using supervised classification based on support vector machine analysis.

RESULTS

This discovery study showed that pancreatitis subtypes could be discriminated with high accuracy. Using unfiltered data, the individual subtypes, as well as the combined pancreatitis cohort, were distinguished from healthy controls with high AUC values (0.96-1.00). Moreover, characteristic protein patterns and AUC values in the range of 0.69-0.95 were observed for the individual pancreatitis entities when compared to each other, and to all other samples combined.

CONCLUSIONS AND CLINICAL RELEVANCE

This study demonstrated the potential of the antibody microarray approach for stratification of pancreatitis. Distinct candidate multiplex serum biomarker signatures for chronic, acute, and autoimmune pancreatitis were defined, which could enhance our fundamental knowledge of the underlying molecular mechanisms, and potentially lead to improved diagnosis.

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.

S100P-binding protein, S100PBP, mediates adhesion through regulation of cathepsin Z in pancreatic cancer cells

Several S100 proteins are up-regulated in pancreatic ductal adenocarcinoma (PDAC), the most significant being S100P. We previously reported on S100PBP, a binding partner of S100P, that shows no homology to any described protein and whose functions are completely unknown. To determine S100PBP expression across human tissues and organs, immunohistochemistry was performed using both multiorgan- and in-house-constructed pancreatic tissue microarrays. To establish S100PBP functions, cell lines with either stably overexpressed or silenced S100PBP were generated and investigated using Affymetrix gene expression arrays and complementary functional assays. We show that S100PBP is differentially expressed in various healthy and tumor specimens, which is both cancer- and tissue-type dependent. In healthy pancreas, S100PBP is expressed in the nuclear/perinuclear region of both exocrine and endocrine compartments. In early precancerous lesions, S100PBP is translocated to the cytoplasm, whereas in PDAC and metastatic lesions, its expression is significantly diminished. The most pronounced phenotypic change after manipulation of S100PBP expression was seen in adhesion; this was significantly reduced after S100PBP up-regulation and increased after S100PBP silencing. Up-regulation or silencing of S100PBP also led to a concomitant change in the levels of the protease cathepsin Z, the silencing of which significantly reduced PDAC cell adhesion. We further demonstrate that the interaction of cathepsin Z with arginine-glycine-aspartic acid-binding integrins, specifically αvβ5, mediates the changes seen in adhesion of PDAC cells.

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 X-deficient gastric epithelial cells in co-culture with macrophages: characterization of cytokine response and migration capability after Helicobacter pylori infection

Our previous studies have shown an association between Helicobacter pylori infection, the strong up-regulation of cathepsin X (CTSX, also called cathepsin Z/P), and the development of gastric cancer. In the present study, we analyzed primary and conventional gastric epithelial cell lines to establish an optimal in vitro mouse model system for the examination of H. pylori-induced overexpression of Ctsx in a functional way. Gastric epithelial cells were isolated from stomachs of wild-type C57BL6/N and Ctsx(-/-) mice and compared with the gastric cancer cell line CLS103. Indirect co-cultures of epithelial cells and macrophages were infected with H. pylori strain SS1 and analyzed for the expression of cathepsins, cytokines, and adhesion factors. Cellular interactions, migration capability, and adherence of H. pylori were assessed using time-lapse video microscopy and colony-forming assays. Isolated primary cells from wild-type and transgenic mice revealed qualities and expression profiles similar to those of corresponding tissue samples. Adherence of H. pylori was significantly higher in primary compared with commercially cells. Thus, induction of cathepsins, cytokines, and adhesion proteins was detected solely in primary cells and co-cultured macrophages. Microarray and migration experiments indicated that Ctsx is involved in B/T-cell proliferation/migration and adhesion of macrophages. Primary epithelial cells from stomach of Ctsx(-/-) mice represent an excellent model of H. pylori gastritis to elaborate the special functions of Ctsx in regulating the immune response to H. pylori.

Cathepsin X is secreted by human osteoblasts, digests CXCL-12 and impairs adhesion of hematopoietic stem and progenitor cells to osteoblasts

BACKGROUND

Hematopoietic stem cells are retained within discrete bone marrow niches through the effects of cell adhesion molecules and chemokine gradients. However, a small proportion of hematopoietic stem cells can also be found trafficking in the peripheral blood. During induced stem cell mobilization a proteolytic microenvironment is generated, but whether proteases are also involved in physiological trafficking of hematopoietic stem cells is not known. In the present study we examined the expression, secretion and function of the cysteine protease cathepsin X by cells of the human bone marrow.

DESIGN AND METHODS

Human osteoblasts, bone marrow stromal cells and hematopoietic stem and progenitor cells were analyzed for the secretion of cathepsin X by western blotting, active site labeling, immunofluorescence staining and activity assays. A possible involvement of cathepsin X in cell adhesion and CXCL-12-mediated cell migration was studied in functional assays. Matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) analysis revealed the digestion mechanism of CXCL-12 by cathepsin X.

RESULTS

Osteoblasts and stromal cells secrete cathepsin X, whereas hematopoietic stem and progenitor cells do not. Using a cathepsin X-selective substrate, we detected the catalytic activity of cathepsin X in cell culture supernatants of osteoblasts. Activated cathepsin X is able to reduce cellular adhesive interactions between CD34(+) hematopoietic stem and progenitor cells and adherent osteoblasts. The chemokine CXCL-12, a highly potent chemoattractant for hematopoietic stem cells secreted by osteoblasts, is readily digested by cathepsin X.

CONCLUSIONS

The exo-peptidase cathepsin X has been identified as a new member of the group of CXCL-12-degrading enzymes secreted by non-hematopoietic bone marrow cells. Functional data indicate that cathepsin X can influence hematopoietic stem and progenitor cell trafficking in the bone marrow.

Angiotensin II-generating enzymes, angiotensin-converting enzyme (ACE) and mast cell chymase (CMA1), in gastric inflammation may be regulated by H. pylori and associated cytokines

BACKGROUND

The local angiotensin II system (LAS) has numerous functions, including the regulation of growth and differentiation in the gastrointestinal tract. Angiotensin II (AngII) may be generated by angiotensin-I-converting enzyme (ACE) or mast cell chymase (CMA1) and plays an important role in inflammatory processes, although opinions differ as to which AngII-generating enzyme is primarily associated with AngII-mediated effects. ACE inhibitors have been shown to have a protective or healing effect on gastric ulcers and colitis in animal models, which could be related to the local expression of ACE.

METHODS

The localisation of ACE and CMA1 was examined immunohistochemically in Helicobacter pylori gastritis, non-H. pylori gastritis, gastric ulcers and non-lesional gastric tissues. Using real-time qRT-PCR, ACE- and CMA1-mRNA expression in gastric cell lines were examined and changes in ACE levels after exposure to H. pylori or cytokines (IL-1beta, IL-6, IL-8, TNF, TGFbeta1) were quantified.

RESULTS

ACE and CMA1 were not expressed in the non-lesional foveolar epithelium. Cytoplasmic staining for ACE in fundic chief cells, and apical membranous expression of ACE in the mucin-secreting cells of the antral and pyloric region was observed. ACE was found in endothelial cells of the gastric ulcer granulation tissue and CMA1 was strongly expressed in mast cells. ACE but not CMA1 was expressed in the MKN28, N87 and MKN45 gastric cell lines, and ACE mRNA expression was regulated by both H. pylori and the cytokines.

CONCLUSIONS

ACE in the gastric mucosa and the microvasculature of granulation tissue may represent a novel therapeutic target for the promotion of healing processes in gastritis and ulceration using ACE inhibitors or AT1R antagonists.

Cathepsin X prevents an effective immune response against Helicobacter pylori infection

Cathepsin X, a cysteine protease, has been shown to regulate an immune response by activating beta-2 integrin receptors. In this study we demonstrate its role in regulating the immune response to infection with H. pylori. The level of cathepsin X was determined in THP-1 monocyte cells primed with H. pylori antigens isolated from subjects suffering from gastritis, who had either eradicated or not the disease after the antibiotic therapy. We show that the specific clinical outcome of H. pylori eradication therapy correlates strongly with the membrane expression of cathepsin X in stimulated THP-1 cells, being significantly higher after stimulation with H. pylori strains from those subjects who did not respond to antibiotic therapy. The same antigens elicit a more vigorous immune response, increased expression of MHC II, however trigger inadequate cytokine profile (IFN-gamma and IL-4) to eradicate the pathogen. We propose that cathepsin X mediated activation of beta-2 integrin receptor Mac-1 suppresses the stimulatory signal in the form of cytokines. Cathepsin X co-localizes on the membrane of THP-1 cells with Mac-1 integrin receptor and its inhibition increases homotypic aggregation and mononuclear cell proliferation, events that are associated with low Mac-1 activity. Our study highlights the diversity of the innate immune response to H. pylori antigens leading to either successful eradication of the infection or maintenance of chronic inflammation, revealing cathepsin X location and activity as a regulator of the effectiveness of H. pylori eradication.

The role of cathepsin X in cell signaling

Cathepsin X is a lysosomal cysteine protease, found predominantly in cells of monocyte/macrophage lineage. It acts as a monocarboxypepidase and has a strict positional and narrower substrate specificity relative to the other human cathepsins. In our recent studies we identified-beta(2) subunit of integrin receptors and alpha and gamma enolase as possible substrates for cathepsin X carboxypeptidase activity. In both cases cathepsin X is capable to cleave regulatory motifs at C-terminus affecting the function of targeted molecules. We demonstrated that via activation of beta(2) integrin receptor Mac-1 (CD11b/CD18) active cathepsin X enhances adhesion of monocytes/macrophages to fibrinogen and regulates the phagocytosis. By activation of Mac-1 receptor cathepsin X may regulate also the maturation of dendritic cells, a process, which is crucial in the initiation of adaptive immunity. Cathepsin X activates also the other beta(2) integrin receptor, LFA-1 (CD11a/CD18) which is involved in the proliferation of T lymphocytes. By modulating the activity of LFA-1 cathepsin X causes cytoskeletal rearrangements and morphological changes of T lymphocytes enhancing ameboid-like migration in 2-D and 3-D barriers and increasing homotypic aggregation. The cleavage of C-terminal amino acids of alpha and gamma enolase by cathepsin X abolishes their neurotrophic activity affecting neuronal cell survival and neuritogenesis.

Regulation of cathepsin X overexpression in H. pylori-infected gastric epithelial cells and macrophages

Cathepsin X (CTSX) is strongly up-regulated in Helicobacter pylori-infected gastric mucosa and intestinal-type gastric cancer. The overexpression of CTSX is mediated predominantly by associated macrophages; depends on a functional type IV-secretion system; and leads to increased migration of gastric epithelial cells. In the present study, we analysed the role of CagA in CTSX overexpression and identified H. pylori-induced inflammatory factors and signalling pathways required for stimulating CTSX expression by H. pylori. Gastric epithelial cells were co-cultured with macrophages in Transwell chambers of 0.4 microm pore size, enabling exchange of fluids but retracting H. pylori. N87 gastric epithelial cells were infected with H. pylori P1 wild-type strain in the presence of inhibitors for p38, JNK, and ERK1/2 signal transduction pathways. Furthermore, cytokines and growth factors were tested for their regulatory function using inhibitory antibodies, and their gene expression was studied by quantitative RT-PCRs and western blots. CTSX is strongly up-regulated at both the mRNA and the protein levels by TNF-alpha, IL-1beta, IL-6, and IL-8, depending on cell type. All these cytokines were found to be increased by five- to ten-fold in macrophages by H. pylori infection of co-cultured N87 gastric epithelial cells. In macrophages, H. pylori up-regulated CTSX via ERK1/2 signalling pathways, and in N87 cells via JNK irrespective of p38 signalling. Our results suggest that H. pylori induced overexpression of CTSX in macrophages and epithelium through specific cytokines that are initiated by CagA-dependent pathways in a cell type-dependent manner.

Ablation of cathepsin k activity in the young mouse causes hypermineralization of long bone and growth plates

Cathepsin K deficiency in humans causes pycnodysostosis, which is characterized by dwarfism and osteosclerosis. Earlier studies of 10-week-old male cathepsin K-deficient (knockout, KO) mice showed their bones were mechanically more brittle, while histomorphometry showed that both osteoclasts and osteoblasts had impaired activity relative to the wild type (WT). Here, we report detailed mineral and matrix analyses of the tibia of these animals based on Fourier transform infrared microspectroscopy and imaging. At 10 weeks, there was significant hypercalcification of the calcified cartilage and cortices in the KO. Carbonate content was elevated in the KO calcified cartilage as well as cortical and cancellous bone areas. These data suggest that cathepsin K does not affect mineral deposition but has a significant effect on mineralized tissue remodeling. Since growth plate abnormalities were extensive despite reported low levels of cathepsin K expression in the calcified cartilage, we used a differentiating chick limb-bud mesenchymal cell system that mimics endochondral ossification but does not contain osteoclasts, to show that cathepsin K inhibition during initial stages of mineral deposition retards the mineralization process while general inhibition of cathepsins can increase mineralization. These data suggest that the hypercalcification of the cathepsin K-deficient growth plate is due to persistence of calcified cartilage and point to a role of cathepsin K in bone tissue development as well as skeletal remodeling.

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.

Regulation of cathepsin K activity by hydrogen peroxide

Although cysteine cathepsins, including cathepsin K, are sensitive to oxidation, proteolytically active forms are found at inflammatory sites. Regulation of cathepsin K activity was analyzed in the presence of H2O2 to gain an insight into these puzzling observations. H2O2 impaired processing of procathepsin K and inactivated its mature form in a time- and dose-dependent mode. However, as a result of the formation of a sulfenic acid, as confirmed by trapping in the presence of 7-chloro-4-nitrobenzo-2-oxa-1,3-diazol, approximately one-third of its initial activity was restored by dithiothreitol. This incomplete inactivation may partially explain why active cysteine cathepsins are still found during acute lung inflammation.

The role of cathepsin X in the migration and invasiveness of T lymphocytes

Cathepsin X is a lysosomal cysteine protease exhibiting carboxypeptidase activity. Its expression is high in the cells of immune system and its function has been related to the processes of inflammatory and immune responses. It regulates processes such as adhesion, T lymphocyte activation and phagocytosis through its interaction with β2 integrins. To investigate the role of cathepsin X in the migration of T lymphocytes, Jurkat T lymphocytes were stably transfected with a pcDNA3 expression vector containing cathepsin X cDNA. The cathepsin-X-overexpressing T lymphocytes exhibited polarised migration-associated morphology, enhanced migration on 2D and 3D models using intercellular adhesion molecule 1 (ICAM1)- and Matrigel-coated surfaces, and increased homotypic aggregation. The increased invasiveness of cathepsin-X-overexpressing cells does not involve proteolytic degradation of extracellular matrix. Confocal microscopy showed that the active mature form of cathepsin X was colocalised in migrating cells together with lymphocyte-function-associated antigen 1 (LFA-1). The colocalisation was particularly evident at the trailing edge protrusion, the uropod, that has an important role in T lymphocyte migration and cell-cell interactions. We propose that cathepsin X causes cytoskeletal rearrangements and stimulates migration of T lymphocytes by modulating the activity of the β2 integrin receptor LFA-1.

The cathepsin family and their role in colorectal cancer

Cathepsins are a class of globular proteases, initially described as intracellular peptide hydrolases, although several cathepsins also have extracellular functions. Cathepsins B, C, F, H, L, K, O, S, V, W, and X are cysteine proteases of the papain family, and represent the largest and best-known class of the cathepsins. Cathepsin G is a serine carboxypeptidases, and cathepsins D and E are aspartic proteases. Cathepsins are synthesized as inactive proenzymes and processed to become mature and active enzymes. Endogenous protein inhibitors, such as cystatins and some serpins, inhibit active enzymes. As primarily lysosomal proteases, cathepsins play important roles in proteolysis during physiological processes, as well as in several diseases. On the basis of their ability to degrade extracellular matrix proteins, cathepsins have been implicated to play a role in invasion and metastasis of colorectal cancer. In the present review, the role of cathepsins in the disease process of colorectal cancers and the correlation of cathepsin expression and activity with clinicopathological features is discussed. Furthermore, we give an overview of the recent developments of cathepsins in animal models and in in vitro experiments of colorectal disease, and provide information on inhibitors of cathepsins as possible therapeutics.

Biochemical properties and regulation of cathepsin K activity

Cysteine cathepsins (11 in humans) are mostly located in the acidic compartments of cells. They have been known for decades to be involved in intracellular protein degradation as housekeeping proteases. However, the discovery of new cathepsins, including cathepsins K, V and F, has provided strong evidence that they also participate in specific biological events. This review focuses on the current knowledge of cathepsin K, the major bone cysteine protease, which is a drug target of clinical interest. Nevertheless, we will not discuss recent developments in cathepsin K inhibitor design since they have been extensively detailed elsewhere. We will cover features of cathepsin K structure, cellular and tissue distribution, substrate specificity, and regulation (pH, propeptide, glycosaminoglycans, oxidants), and its putative roles in physiological or pathophysiological processes. Finally, we will review the kinetic data of its inhibition by natural endogenous inhibitors (stefin B, cystatin C, H- and L-kininogens).

Protein and non-protein sulfhydryls and disulfides in gastric mucosa and liver after gastrotoxic chemicals and sucralfate: Possible new targets of pharmacologic agents

AIM: To investigate the role of major non-protein and protein sulfhydryls and disulfides in chemically induced gastric hemorrhagic mucosal lesions (HML) and the mechanism of gastroprotective effect of sucralfate.

METHODS: Rats were given 1 mL of 75% ethanol, 25% NaCl, 0.6 mol/L HCl, 0.2 mol/L NaOH or 1% ammonia solutions intragastrically (i.g.) and sacrificed 1, 3, 6 or 12 min later. Total (reduced and oxidized) glutathione (GSH + GSSG), glutathione disulfide (GSSG), protein free sulfhydryls (PSH), protein-glutathione mixed disulfides (PSSG) and protein cystine disulfides (PSSP) were measured in gastric mucosa and liver.

RESULTS: Reduced glutathione (GSH) was depleted in the gastric mucosa after ethanol, HCl or NaCl exposure, while oxidized glutathione (GSSG) concentrations increased, except by HCl and NaOH exposure. Decreased levels of PSH after exposure to ethanol were observed, NaCl or NaOH while the total protein disulfides were increased. Ratios of reduced to oxidized glutathione or sulfhydrils to disulfides were decreased by all chemicals. No changes in thiol homeostasis were detected in the liver after i.g. abbreviation should be spelled out the first time here administration of ethanol. Sucralfate increased the concentrations of GSH and PSH and prevented the ethanol-induced changes in gastric mucosal thiol concentrations.

CONCLUSION: Our modified methods are now suitable for direct measurements of major protein and non-protein thiols/disulfides in the gastric mucosa or liver. A common element in the pathogenesis of chemically induced HML and in the mechanism of gastroprotective drugs seems to be the decreased ratios of reduced and oxidized glutathione as well as protein sulfhydryls and disulfides.

Cysteine cathepsins: regulators of antitumour immune response

Cysteine cathepsins are lysosomal cysteine proteases that are involved in a number of important biological processes, including intracellular protein turnover, propeptide and hormone processing, apoptosis, bone remodelling and reproduction. In cancer, the cathepsins have been linked to extracellular matrix remodelling and to the promotion of tumour cell motility, invasion, angiogenesis and metastasis, resulting in poor outcome of cancer patients; however, cysteine cathepsins are also involved at different levels of the innate and adaptive immune responses. Their best known role in this aspect is their contribution to major histocompatibility complex class II antigen presentation, the processing of progranzymes into proteolytically active forms, cytotoxic lymphocyte self-protection, cytokine and growth factor degradation and, finally, the induction of cytokine expression and modulation of integrin function. This review is focused on the role of cysteine cathepsins in the antitumour immune response and the evaluation of their pro- and anticancer behaviours during the regulation of these processes.

Gene profiling of cathepsin K deficiency in atherogenesis: profibrotic but lipogenic

Recently, we showed that cathepsin K deficiency reduces atherosclerotic plaque progression, induces plaque fibrosis, but aggravates macrophage foam cell formation in the ApoE -/- mouse. To obtain more insight into the molecular mechanisms by which cathepsin K disruption evokes the observed phenotypic changes, we used microarray analysis for gene expression profiling of aortic arches of CatK -/-/ApoE -/- and ApoE -/- mice on a mouse oligo microarray. Out of 20 280 reporters, 444 were significantly differentially expressed (p-value of < 0.05, fold change of > or = 1.4 or < or = - 1.4, and intensity value of > 2.5 times background in at least one channel). Ingenuity Pathway Analysis and GenMAPP revealed upregulation of genes involved in lipid uptake, trafficking, and intracellular storage, including caveolin - 1, - 2, - 3 and CD36, and profibrotic genes involved in transforming growth factor beta (TGFbeta) signalling, including TGFbeta2, latent TGFbeta binding protein-1 (LTBP1), and secreted protein, acidic and rich in cysteine (SPARC), in CatK -/-/ApoE -/- mice. Differential gene expression was confirmed at the mRNA and protein levels. In vitro modified low density lipoprotein (LDL) uptake assays, using bone marrow derived macrophages preincubated with caveolae and scavenger receptor inhibitors, confirmed the importance of caveolins and CD36 in increasing modified LDL uptake in the absence of cathepsin K. In conclusion, we suggest that cathepsin K deficiency alters plaque phenotype not only by decreasing proteolytic activity, but also by stimulating TGFbeta signalling. Besides this profibrotic effect, cathepsin K deficiency has a lipogenic effect owing to increased lipid uptake mediated by CD36 and caveolins.

Helicobacter pylori-induced downregulation of the secretory leukocyte protease inhibitor (SLPI) in gastric epithelial cell lines and its functional relevance for H. pylori-mediated diseases

The secretory leukocyte protease inhibitor (SLPI) exerts antiproteolytic activity towards serine proteases, as well as anti-microbial and anti-inflammatory effects. To investigate its role in H. pylori-mediated diseases, SLPI expression was analyzed by RT-PCR, ELISA and immunohistochemistry in clinical samples and gastric tumor cell lines. Determination of the mucosal SLPI levels in 126 patients confirmed the previously reported downregulation of SLPI in H. pylori-infected patients. The lower SLPI levels in antral biopsies of H. pylori-positive subjects were associated with a 30-fold increase (p<0.01) in neutrophil elastase activity, and a significant negative correlation was demonstrated for both parameters (R=-0.63, p=0.0002). Eradication of the bacterium in a long-term study (5-7 years) led to a recovery of mucosal SLPI expression. In vitro experiments using four gastric tumor cell lines (AGS, MKN-28, MKN-45, NCI-N87) generally confirmed the clinical findings. While the co-incubation of these cell lines with H. pylori resulted in lower or unchanged SLPI protein levels, the corresponding SLPI mRNA amounts were upregulated by up to five-fold (p=0.006) in all cell lines. Taken together, these results indicate that the reduction in antral SLPI levels in H. pylori-infected subjects has a functional relevance for gastric mucosa and the H. pylori-induced decrease in SLPI is primarily regulated at the posttranslational level.

Carboxypeptidase cathepsin X mediates β2-integrin-dependent adhesion of differentiated U-937 cells

Cathepsin X is a lysosomal carboxypeptidase with a potential role in processes of inflammation and immune response. The integrin-binding motifs RGD and ECD, present in the pro- and in mature forms of cathepsin X, respectively, suggest that this enzyme might have a function in cell signaling and adhesion. In this study, we report that cysteine protease inhibitors E-64 and CA-074 and 2F12 monoclonal antibody, all of which inhibit cathepsin X activity, significantly reduced adhesion of differentiated U-937 cells to polystyrene- and fibrinogen-coated surfaces via Mac-1 integrin receptor, whereas their binding to vitronectin, fibronectin or Matrigel was not affected. On the other hand, cathepsin X, added to differentiating U-937 cells, stimulated their adhesion. Using confocal microscopy, we demonstrated that the pro-form of cathepsin X was co-localized with beta(2) and beta(3) integrin subunits and its mature form solely with the beta(2) integrin subunit with the most intense signal in cell-cell junctions in differentiated U-937 cells and in co-cultures with endothelial cells. Our results indicate that active cathepsin X mediates the function of beta(2) integrin receptors during cell adhesion and that it could also be involved in other processes associated with beta(2) integrin receptors such as phagocytosis and T cell activation.

Helicobacter pylori infection, but not low-dose aspirin, results in a local reduction of the secretory leukocyte protease inhibitor in gastroduodenal mucosa

BACKGROUND

The secretory leukocyte protease inhibitor (SLPI) represents a multifunctional protein with mucosa-protective features. Helicobacter pylori and the usage of low-dose aspirin are two independent risk factors for the development of gastrointestinal diseases. Therefore, the effect of low-dose aspirin on gastrointestinal SLPI expression was analyzed in the context of H. pylori infection.

MATERIAL AND METHODS

The study included 20 volunteers (H. pylori positive and negative: n = 10) who received 2 x 50 mg aspirin/day for 7 days. H. pylori-positive subjects underwent eradication therapy and repeated the protocol. Gastroduodenoscopy was performed at day 0, 1, 3, and 7, and biopsies were obtained each from antrum, corpus, and duodenal bulb. SLPI expression was determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

A reduction of antral SLPI levels, ranging between 582 (day 0) and 941 pg/10 microg protein (day 7), was determined in H. pylori-positive compared to H. pylori-negative and -eradicated subjects (1600-2050 pg/10 microg protein, ANOVA: p = .001-.045). No differences concerning aspirin were observed within the groups. SLPI levels in corpus and duodenal mucosa were neither affected by H. pylori nor low-dose aspirin. There was an inverse correlation between SLPI and H. pylori-induced inflammation (activity: r = -0.575, -0.69 to -0.43, p < .0001; chronicity: r = -0.54, -0.66 to -0.39, p < .0001) in antral mucosa only, whereas other locations as well as the usage of low-dose aspirin did not show an association between SLPI and inflammation.

CONCLUSIONS

H. pylori infection, but not the usage of low-dose aspirin, has a role in the down-regulation of antral SLPI levels.

Up-regulation of cathepsin X in Helicobacter pylori gastritis and gastric cancer

Recently, we identified increased cathepsin X expression in H. pylori-infected gastric mucosa. Here, we describe further up-regulation in gastric cancer and report on the role of inflammatory cytokines required for cathepsin X up-regulation in H. pylori-infected gastric mucosa, as well as on consequences for cellular invasion. Biopsy specimens were taken from the antrum, corpus and cardia of H. pylori-infected and non-infected patients. Gastric cancer samples were obtained from patients undergoing gastric surgery. Cathepsin X was detected in gastric mucosa by quantitative real-time RT-PCR, western blotting and immunohistochemistry. Induction of cathepsin X expression in epithelial and inflammatory cells caused by H. pylori infection was tested in in vitro contact and non-contact co-cultures of AGS cells and monocytic cells. Patients with H. pylori gastritis showed significantly higher cathepsin X mRNA (2.5-fold) and protein (1.6-fold) expression than H. pylori-negative patients. Cathepsin X was also up-regulated in gastric cancer (3-12-fold) compared to non-neoplastic mucosa. Cathepsin X was predominantly expressed by macrophages in the mucosal stroma and in glands of the antral mucosa. In addition, tumour cells stained for cathepsin X in 26 (68%) patients with gastric carcinoma. In general, staining was significantly more common (20 vs. 6 patients) and more intense (3.55 vs. 0.83) in intestinal type gastric cancer than in the diffuse type. In vitro cell culture experiments revealed that intercellular signalling between pathogenicity island (PAI)-positive H. pylori-infected epithelial cells and macrophages via soluble factors in the culture medium seems to be responsible for increased expression of cathepsin X in monocytes. Using antisense oligonucleotides, cathepsin X up-regulation was directly associated with higher invasiveness in vitro. Although no correlation of cathepsin X expression and TNM stage was found, our study demonstrates that cathepsin X plays a role not only in the chronic inflammation of gastric mucosa but also in the tumourigenesis of gastric cancer.

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.

Carboxypeptidases cathepsins X and B display distinct protein profile in human cells and tissues

Cathepsin X, a recently discovered lysosomal cysteine protease, shares common structural features and activity properties with cysteine protease cathepsin B. Based on its widespread mRNA distribution in primary tumors and tumor cell lines, a redundant function in tumor progression has been proposed. In this study, we have shown that these two related proteases exhibit different profiles with respect to their protein distribution in cells and tissues and to their possible roles in malignancy. Protein level of cathepsin X did not differ significantly between matched pairs of lung tumor and adjacent lung tissue obtained from patients with lung cancer whereas that of cathepsin B was 9.6-fold higher in tumor compared to adjacent lung tissue. Immunohistochemical analysis of lung tumor cathepsin X revealed very faint staining in tumor cells but positive staining in infiltrated histiocytes, alveolar macrophages, bronchial epithelial cells, and alveolar type II cells. Cathepsin X stained positive also in CD68+ cells in germinal centers of secondary follicles in lymph nodes, corresponding to tingible body macrophages. Two cell lines with proven invasive behavior, MCF-10A neoT and MDA-MB 231, showed positive staining for cathepsin B, but negative for cathepsin X. We showed that the invasive potential of MCF-10A neoT cells can be impaired by specific inhibitor of cathepsin B but not by that of cathepsin X. Cathepsin X was found in large amounts in the pro-monocytic U-937 cell line, in monocytes and in dendritic cells, generated from monocytes in vitro. Our results show that cathepsin X is not involved in degradation of extracellular matrix, a proteolytic event leading to tumor cell invasion and metastasis. Its expression, restricted to immune cells suggests a role in phagocytosis and the regulation of immune response.

Identification of a novel isoform predominantly expressed in gastric tissue and a triple-base pair polymorphism of the cathepsin W gene

In order to investigate the prevalence of potential polymorphisms of the cathepsin W gene, the complete cDNA of 50 dyspeptic patients was analyzed. From those 37 (74%) revealed the wildtype sequence, 6 samples (12%) contained independent single base pair changes including 4 silent and 2 with amino acid changes. Furthermore, a triple-base pair polymorphism was found in 7 samples (14%, 4x heterozygous, 3x homozygous) leading to the following changes: F(217)S, H(248)Y, and I(250)T. Furthermore, a novel alternative splice variant concerning intron 10 was identified in 6 samples (12%). Notably, this novel isoform was only found in samples of gastric mucosa lymphocytes, whereas peripheral NK cells expressed cathepsin W wildtype only. Taken together, this study demonstrated for the fist time that a genetic variant and a novel isoform of cathepsin W are present in about 14% and 12%, respectively, within the Caucasian population.