Pyrocurzerenone is a natural compound found in Curcuma zedoaria and Chloranthus serratus. However, the anticancer effect of pyrocurzerenone in oral cancer remains unclear. Using the MTT assay, wound healing assay, transwell assay and western blot analysis, we investigated the impact of pyrocurzerenone on antimetastatic activity, as well as the critical signalling pathways that underlie the processes of oral cancer cell lines SCC-9, SCC-1 and SAS in this work. Our findings suggested that pyrocurzerenone inhibits cell migration and invasion ability in oral cancer cell lines. Furthermore, phosphorylation of ERK1/2 had significant inhibitory effects in SCC-9 and SCC-1 cell lines. Combining ERK1/2 inhibitors with pyrocurzerenone decreased the migration and invasion activity of SCC-9 and SCC-1 cell lines. We also found that the expressed level of cathepsin S decreased under pyrocurzerenone treatment. This study showed that pyrocurzerenone reduced ERK1/2 expression of the proteins and cathepsin S, suggesting that it could be a valuable treatment to inhibit human oral cancer cell metastasis.

Research on the markers of autoimmune response in multiple sclerosis (MS) is still of great importance. The aim of our study was the evaluation of plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations as potential biomarkers of a relapsing-remitting type of MS (RRMS). Surface plasmon resonance imaging (SPRI) biosensors were used for the evaluation of protein concentrations. Plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations were significantly higher in RRMS patients compared to the control group. All three parameters were characterized by excellent usefulness in differentiating MS patients from healthy individuals (AUC equal to or close to 1.000). The plasma concentration of analyzed parameters was not correlated with severity of disability in the course of RRMS (EDSS value), the number of years from the first MS symptoms, the number of years from MS diagnosis, or the number of relapses within the 24-month observational period. Our study has shown that plasma concentrations of 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S have promising potential in differentiating RRMS patients from healthy individuals. All of the analyzed parameters were found to be independent of the time of MS relapse and the severity of neurological symptoms. Hence, their potential as highly sensitive and independent circulating markers of RRMS suggests a stronger association with immunological activity (inflammatory processes) than with the severity of the disease.

We aimed to determine the role of cathepsin S (CTSS) in modulating oxidative stress-induced immune and inflammatory reactions and angiogenesis in age-related macular degeneration. Human retinal pigment epithelium cells line ARPE-19 (immature) were maintained and treated with H2O2. The expression of CTSS, inflammatory cytokines, and complement factors induced by oxidative stress was compared between cells incubated without (control) and with CTSS knockdown (using small interfering ribonucleic acid; siRNA). To evaluate the role of CTSS in angiogenesis, we assayed tube formation using human umbilical vein endothelial cells and conditioned medium from ARPE-19 cells. We also used a mouse model of laser-induced choroidal neovascularization. CTSS levels were higher in ARPE-19 cells treated with H2O2 than in control cells. Oxidative stress-induced CTSS resulted in significantly elevated transcription of nuclear factor kappa B-dependent inflammatory cytokines, complement factors C3a and C5a, membrane attack complex (C5b-9), and C3a and C5a receptors. siRNA-mediated knockdown of CTSS reduced the number of inflammatory signals. Furthermore, oxidative stress-induced CTSS regulated the expression of peroxisome proliferator-activated receptor γ and vascular endothelial growth factor A/Akt serine/threonine kinase family signaling, which led to angiogenesis. Tube formation assays and mouse models of choroidal neovascularization revealed that CTSS knockdown ameliorated angiogenesis in vitro and in vivo. The present findings suggest that CTSS modulates the complement pathway, inflammatory reactions, and neovascularization, and that CTSS knockdown induces potent immunomodulatory effects. Hence, it could be a promising target for the prevention and treatment of early- and late-stage age-related macular degeneration.

BACKGROUND: Cathepsin S (CTSS) is a cysteine protease that played diverse roles in immunity, tumor metastasis, aging and other pathological alterations. At the cellular level, increased CTSS levels have been associated with the secretion of pro-inflammatory cytokines and disrupted the homeostasis of Ca2+ flux. Once CTSS was suppressed, elevated levels of anti-inflammatory cytokines and changes of Ca2+ influx were observed. These findings have inspired us to explore the potential role of CTSS on cognitive functions.
METHODS: We conducted classic Y-maze and Barnes Maze tests to assess the spatial and working memory of Ctss-/- mice, Ctss+/+ mice and Ctss+/+ mice injected with the CTSS inhibitor (RJW-58). Ex vivo analyses including long-term potentiation (LTP), Golgi staining, immunofluorescence staining of sectioned whole brain tissues obtained from experimental animals were conducted. Furthermore, molecular studies were carried out using cultured HT-22 cell line and primary cortical neurons that treated with RJW-58 to comprehensively assess the gene and protein expressions.
RESULTS: Our findings reported that targeting cathepsin S (CTSS) yields improvements in cognitive function, enhancing both working and spatial memory in behavior models. Ex vivo studies showed elevated levels of long-term potentiation levels and increased synaptic complexity. Microarray analysis demonstrated that brain-derived neurotrophic factor (BDNF) was upregulated when CTSS was knocked down by using siRNA. Moreover, the pharmacological blockade of the CTSS enzymatic activity promoted BDNF expression in a dose- and time-dependent manner. Notably, the inhibition of CTSS was associated with increased neurogenesis in the murine dentate gyrus. These results suggested a promising role of CTSS modulation in cognitive enhancement and neurogenesis.
CONCLUSIONS: Our findings suggest a critical role of CTSS in the regulation of cognitive function by modulating the Ca2+ influx, leading to enhanced activation of the BDNF/TrkB axis. Our study may provide a novel strategy for improving cognitive function by targeting CTSS.

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of bovine paratuberculosis, a chronic granulomatous enteritis leading to economic losses and posing a risk to human health due to its zoonotic potential. The pathogen cannot reliably be detected by standard methods, and immunological procedures during the infection are not well understood. Therefore, the aim of our study was to explore host-pathogen interactions in MAP-infected dairy cows and to improve diagnostic tests. Serum proteomics analysis using quantitative label-free LC-MS/MS revealed 60 differentially abundant proteins in MAP-infected dairy cows compared to healthy controls from the same infected herd and 90 differentially abundant proteins in comparison to another control group from an uninfected herd. Pathway enrichment analysis provided new insights into the immune response to MAP and susceptibility to the infection. Furthermore, we found a higher abundance of Cathepsin S (CTSS) in the serum of MAP-infected dairy cows, which is involved in multiple enriched pathways associated with the immune system. Confirmed with Western blotting, we identified CTSS as a potential biomarker for bovine paratuberculosis. This study enabled a better understanding of procedures in the host-pathogen response to MAP and improved detection of paratuberculosis-diseased cattle.

OBJECTIVE: Endometriosis is a common disease with a complex pathomechanism and atypical symptoms, often leading to delayed diagnosis. Currently, the sole method for confirming the presence of the disease is through laparoscopy and histopathological examination of collected tissue. However, this invasive procedure carries potential risk and complications, necessitating the exploration of non-surgical diagnostic methods for endometriosis. This study aims to analyze peritoneal fluid and plasma samples for the expression of cathepsin L and cathepsin S to identify potential biomarkers for non-invasive diagnostic approaches to endometriosis.
METHODS: In this cross-sectional study, plasma and peritoneal fluid samples were obtained during laparoscopy from 63 patients diagnosed with chronic pelvic pain or infertility. The study group consisted of women with confirmed endometriosis. The concentrations of cathepsins L and S were determined using an SPRi biosensor.
RESULTS: The study did not reveal significant differences in the concentrations of cathepsin L and cathepsin S between the control group and the study group, both in peritoneal fluid and plasma.
CONCLUSIONS: Based on the results of this study, it appears that cathepsins L and S are not suitable candidates as biomarkers for endometriosis.

This study aimed to identify potential therapeutic targets of artesunate in an MRL/lpr lupus nephritis mouse model by quantitative proteomics. We detected serum autoimmune markers and proteinuria in 40 female mice that were divided into 4 groups (n = 10): normal C57BL/6 control group; untreated MRL/lpr lupus; 9 mg/kg/day prednisone positive control MRL/lpr lupus; and 15 mg/kg/day artesunate-treated MRL/lpr lupus groups. Renal pathology in the untreated MRL/lpr lupus and artesunate groups was examined by Periodic acid-Schiff (PAS) staining. Artesunate treatment in lupus mice decreased serum autoantibody levels and proteinuria while alleviating lupus nephritis pathology. Through tandem mass tag-tandem mass spectrometry (TMT-MS/MS) analyses, differentially expressed proteins were identified in the artesunate group, and subsequent functional prediction suggested associations with antigen presentation, apoptosis, and immune regulation. Data are available via ProteomeXchange with the identifier PXD046815. Parallel reaction monitoring (PRM) analysis of the top 19 selected proteins confirmed the TMT-MS/MS results. Immunohistochemistry, immunofluorescence, and Western blotting of an enriched protein from PRM analysis, cathepsin S, linked to antigen presentation, highlighted its upregulation in the untreated MRL/lpr lupus group and downregulation following artesunate treatment. This study suggests that artesunate holds potential as a therapeutic agent for lupus nephritis, with cathepsin S identified as a potential target.

Epithelial sodium channel (ENaC) are integral to maintaining salt and water homeostasis in various biological tissues, including the kidney, lung, and colon. They enable the selective reabsorption of sodium ions, which is a process critical for controlling blood pressure, electrolyte balance, and overall fluid volume. ENaC activity is finely controlled through proteolytic activation, a process wherein specific enzymes, or proteases, cleave ENaC subunits, resulting in channel activation and increased sodium reabsorption. This regulatory mechanism plays a pivotal role in adapting sodium transport to different physiological conditions. In this review article, we provide an in-depth exploration of the role of proteolytic activation in regulating ENaC activity. We elucidate the involvement of various proteases, including furin-like convertases, cysteine, and serine proteases, and detail the precise cleavage sites and regulatory mechanisms underlying ENaC activation by these proteases. We also discuss the physiological implications of proteolytic ENaC activation, focusing on its involvement in blood pressure regulation, pulmonary function, and intestinal sodium absorption. Understanding the mechanisms and consequences of ENaC proteolytic activation provides valuable insights into the pathophysiology of various diseases, including hypertension, pulmonary disorders, and various gastrointestinal conditions. Moreover, we discuss the potential therapeutic avenues that emerge from understanding these mechanisms, offering new possibilities for managing diseases associated with ENaC dysfunction. In summary, this review provides a comprehensive discussion of the intricate interplay between proteases and ENaC, emphasizing the significance of proteolytic activation in maintaining sodium and fluid balance in both health and disease.

The cathepsin S (CTSS) gene encodes a lysine cysteine protease and serves an important role in the development of autoimmune diseases, inflammation and nervous system diseases. Furthermore, CTSS is implicated in tumor invasion and metastasis by the induction of tumor angiogenesis and the degradation of the tumor extracellular matrix. Nevertheless, the precise impact of CTSS on predicting pan-cancer prognosis and its influence on the tumor microenvironment and immune infiltration in human cancers remains unknown. This present study employed a comprehensive array of bioinformatic methods to evaluate the expression of CTSS and its associations with prognosis, clinicopathological characteristics, tumor microenvironment, tumor immune infiltration, tumor mutational burden and microsatellite instability across numerous cancer types. The current study demonstrated abnormal expression and distinct genomic alteration profiles of CTSS in many of the cancers tested. Furthermore, CTSS expression exhibited close associations with the prognosis of numerous cancers. High CTSS expression was significantly associated with better overall survival and disease-specific survival in bladder urothelial carcinoma (BLCA) and skin cutaneous melanoma (SKCM) but worse outcomes in brain lower grade glioma (LGG) and uveal melanoma (UVM). Moreover, CTSS demonstrated significant correlations with tumor mutational burden and microsatellite instability in 8 and 12 cancer types respectively, as well as different responses in immunotherapy sub-cohorts, especially in melanoma and bladder cancers. CTSS expression showed a positive correlation with stromal and immune cell scores in the four aforementioned cancers. Moreover, CTSS expression was correlated with the number of infiltrating CD8+ T cells, CD4+ T cells and macrophages. Conversely, CTSS was negatively associated with resting Mast cells, resting NK cells and resting memory CD4+ T cell infiltration in BLCA, SKCM and kidney renal clear cell carcinoma (KIRC). Furthermore, CTSS expression was correlated with immune-related gene expression, notably PDCD1, LAG3, PDCD1 and TIGIT in BLCA, KIRC, SKCM, LGG and UVM. Functional enrichment analysis suggested that CTSS could drive a dynamic adjustment of biological functions and pathways in BLCA, SKCM, LGG and UVM, including immune response regulating signaling pathways, regulation of lymphocyte activation and T cell receptor singling pathways. The current study suggested that CTSS could be an essential biomarker for prognosis and immune infiltration features in multiple cancers.

Cathepsin S (CTSS) is involved in pathogenesis of many human diseases. Inhibitors blocking its protease activity hold therapeutic potential. In comparison to small-molecule inhibitors, monoclonal antibodies capable of inhibiting CTSS enzymatic activity may possess advantageous pharmacological properties. Here we designed and produced inhibitory antibodies targeting human CTSS by genetically fusing the propeptide of procathepsin S (proCTSS) with antibodies in clinic. The resulting antibody fusions in full-length or fragment antigen-binding format could be stably expressed and potently inhibit CTSS proteolytic activity in high specificity. These fusion antibodies not only demonstrate a new approach for facile synthesis of antibody inhibitors against CTSS, but also represent novel anti-CTSS therapeutic candidates.