Cathepsin B-Activatable Bioactive Peptide Nanocarrier for High-Efficiency Immunotherapy of Asthma.

Introduction: Asthma, a chronic respiratory disease closely associated with inflammation, presents ongoing treatment challenges. IALLIPF (le-Ala-Leu-Leu-Ile-Pro-Phe) is one of millet prolamins peptides (MPP) which shows anti-oxidant bioactivity by reducing the production of reactive oxygen species (ROS). Tryptophan (Trp, W) is an amino acid that has been demonstrated to possess anti-inflammatory effects. We introduce a novel cathepsin B-activatable bioactive peptides nanocarrier, PEG-IALLIPF-GFLG-W (MPP-Trp), designed for immunotherapy of asthma. Methods: MPP-Trp is synthesized, purified, and its characteristics are investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The yield of nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-6 and IL-1ß) are examined to evaluate anti-inflammatory effects of IALLIPF, Trp and MPP-Trp. The immunomodulatory effects of IALLIPF, Trp and MPP-Trp on Th1/Th2 cell populations and cytokines are investigated by flow cytometry, qRT-PCR and ELISA assays. We explore the therapeutic effect of MPP-Trp in the mouse model of asthma by the analysis of lung histology and ELISA. It is necessary to study the biocompatibility of MPP-Trp by CCK8 assay and histopathologic analysis using hematoxylin and eosin (HE) staining. Results: In asthmatic peripheral blood mononuclear cells (PBMCs), IALLIPF, Trp and MPP-Trp are able to significantly alleviate inflammation by inhibiting the yield of nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-6 and IL-1ß), especially MPP-Trp. MPP-Trp significantly upregulates Th1 cell levels while notably reducing Th2 cell levels. Furthermore, MPP-Trp effectively elevates the expression and production of interferon-gamma (IFN-γ), an essential cytokine from Th1 cells. Additionally, MPP-Trp markedly diminishes the mRNA expression and levels of key asthma pathogenesis cytokines, such as interleukin-4 (IL-4), interleukin-13 (IL-13), and interleukin-5 (IL-5), in asthma PBMCs. MPP-Trp ameliorates pulmonary pathological alterations and significantly inhibits OVA-induced inflammation in mice with asthma. It has little influence on the cell viability in Asthma-PBMCs treated with various concentrations or durations of MPP-Trp. No pathological changes, including in the heart, liver, spleen, lung, and kidney tissues, are observed in non-sensitized and non-challenged mice treated with MPP-Trp (20 mg/kg). Discussion: Our research demonstrates that MPP-Trp has immunomodulatory effects on Th1/Th2 cell populations, essential in managing asthma. It considerably alleviates OVA-induced asthma by shifting the immune response towards a Th1-dominant profile, thereby reducing Th2-driven inflammation. Therefore, this novel bioactive peptide nanocarrier, MPP-Trp, holds promise as a candidate for asthma immunotherapy.

Cell-specific cross-talk proteomics reveals cathepsin B signaling as a driver of glioblastoma malignancy near the subventricular zone.

Glioblastoma (GBM) is the most prevalent and aggressive malignant primary brain tumor. GBM proximal to the lateral ventricles (LVs) is more aggressive, potentially because of subventricular zone contact. Despite this, cross-talk between GBM and neural stem/progenitor cells (NSC/NPCs) is not well understood. Using cell-specific proteomics, we show that LV-proximal GBM prevents neuronal maturation of NSCs through induction of senescence. In addition, GBM brain tumor-initiating cells (BTICs) increase expression of cathepsin B (CTSB) upon interaction with NPCs. Lentiviral knockdown and recombinant protein experiments reveal that both cell-intrinsic and soluble CTSB promote malignancy-associated phenotypes in BTICs. Soluble CTSB stalls neuronal maturation in NPCs while promoting senescence, providing a link between LV-tumor proximity and neurogenesis disruption. Last, we show LV-proximal CTSB up-regulation in patients, showing the relevance of this cross-talk in human GBM biology. These results demonstrate the value of proteomic analysis in tumor microenvironment research and provide direction for new therapeutic strategies in GBM.

Discovery of Novel HDAC3 Inhibitors with PD-L1 Downregulating/Degrading and Antitumor Immune Effects.

Targeting the programmed cell death-1/ligand 1 (PD-1/PD-L1) pathway is one of the most promising cancer treatment strategies. Studies have shown that HDAC inhibitors can enhance the antitumor immune response by modulating the expression of PD-L1. Herein, we designed and synthesized a series of novel hydrazide-based small molecule HDAC inhibitors; among them, compound HQ-30 showed selective HDAC3 inhibition (IC50 = 89 nM) and remarkable PD-L1-degrading activity (DC50 = 5.7 µM, Dmax = 80% at 10 µM). Further studies revealed that HQ-30 induced the degradation of PD-L1 by regulating cathepsin B (CTSB) in the lysosomes. Further, HQ-30 could enhance the infiltration of CD3+ CD4+ helper T and CD3+ CD8+ cytotoxic T cells in tumors, thus activating the tumor immune microenvironment. Moreover, HQ-30 possessed a benign toxicity profile (LD50 > 1000 mg/kg) and favorable pharmacokinetic properties (F = 57%). Taken together, HQ-30 is worthy of further investigation as a small molecule-based epigenetic modulator of tumor immunotherapy.

Milk Fat Globule Membrane-Containing Protein Powder Promotes Fitness in Caenorhabditis elegans.

Milk-derived peptides and milk fat globule membrane (MFGM) have gained interest as health-promoting food ingredients. However, the mechanisms by which these nutraceuticals modulate the function of biological systems often remain unclear. We utilized Caenorhabditis elegans to elucidate how MFGM-containing protein powder (MProPow), previously used in a clinical trial, affect the physiology of this model organism. Our results demonstrate that MProPow does not affect lifespan but promotes the fitness of the animals. Surprisingly, gene expression analysis revealed that MProPow decreases the expression of genes functioning on innate immunity, which also translates into reduced survival on pathogenic bacteria. One of the innate immunity-associated genes showing reduced expression upon MProPow supplementation is cpr-3, the homolog of human cathepsin B. Interestingly, knockdown of cpr-3 enhances fitness, but not in MProPow-treated animals, suggesting that MProPow contributes to fitness by downregulating the expression of this gene. In summary, this research highlights the value of C. elegans in testing the biological activity of food supplements and nutraceuticals. Furthermore, this study should encourage investigations into whether milk-derived peptides and MFGM mediate their beneficial effects through the modulation of cathepsin B expression in humans.

Rapamycin and Starvation Mitigate Indomethacin-Induced Intestinal Damage through Preservation of Lysosomal Vacuolar ATPase Integrity.

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess anti-inflammatory, antipyretic, and analgesic properties and are among the most commonly used drugs. Although the cause of NSAID-induced gastric ulcers is well understood, the mechanism behind small intestinal ulcers remains elusive. In this study, we examined the mechanism through which indomethacin (IM), a prominent NSAID, induces small intestinal ulcers, both in vitro and in vivo. In IEC6 cells, a small intestinal epithelial cell line, IM treatment elevated levels of LC3-II and p62. These expression levels remained unaltered after treatment with chloroquine or bafilomycin, which are vacuolar ATPase (V-ATPase) inhibitors. IM treatment reduced the activity of cathepsin B, a lysosomal protein hydrolytic enzyme, and increased the lysosomal pH. There was a notable increase in subcellular colocalization of LC3 with Lamp2, a lysosome marker, post IM treatment. The increased lysosomal pH and decreased cathepsin B activity were reversed by pretreatment with rapamycin (Rapa) or glucose starvation, both of which stabilize V-ATPase assembly. To validate the in vitro findings in vivo, we established an IM-induced small intestine ulcer mouse model. In this model, we observed multiple ulcerations and heightened inflammation following IM administration. However, pretreatment with Rapa or fasting, which stabilize V-ATPase assembly, mitigated the IM-induced small intestinal ulcers in mice. Coimmunoprecipitation studies demonstrated that IM binds to V-ATPase in vitro and in vivo. These findings suggest that IM induces small intestinal injury through lysosomal dysfunction, likely due to the disassembly of lysosomal V-ATPase caused by direct binding. Moreover, Rapa or starvation can prevent this injury by stabilizing the assembly. SIGNIFICANCE STATEMENT: This study elucidates the largely unknown mechanisms behind small intestinal ulceration induced by indomethacin and reveals the involvement of lysosomal dysfunction via vacuolar ATPase disassembly. The significance lies in identifying potential preventative interventions, such as rapamycin treatment or glucose starvation, offering pivotal insights that extend beyond nonsteroidal anti-inflammatory drugs-induced ulcers to broader gastrointestinal pathologies and treatments, thereby providing a foundation for novel therapeutic strategies aimed at a wide array of gastrointestinal disorders.

Late-Stage Desulfurization Enables Rapid and Efficient Solid-Phase Synthesis of Cathepsin-Cleavable Linkers for Antibody-Drug Conjugates.

The synthesis of linker-payloads is a critical step in developing antibody-drug conjugates (ADCs), a rapidly advancing therapeutic approach in oncology. The conventional method for synthesizing cathepsin B-labile dipeptide linkers, which are commonly used in ADC development, involves the solution-phase assembly of cathepsin B-sensitive dipeptides, followed by the installation of self-immolative para-aminobenzyl carbonate to facilitate the attachment of potent cytotoxic payloads. However, this approach is often low yield and laborious, especially when extending the peptide chain with components like glutamic acid to improve mouse serum stability or charged amino acids or poly(ethylene glycol) moieties to enhance linker hydrophilicity. Here, we introduce a novel approach utilizing late-stage desulfurization chemistry, enabling safe, facile, and cost-effective access to the cathepsin B-cleavable linker, Val-Ala-PABC-MMAE, on resin for the first time.

Synthesis and Evaluation of a Cathepsin B-Recognizing Trifunctional Chelating Agent to Improve Tumor Retention of Radioimmunoconjugates.

Cathepsin B (CTSB) is a lysosomal protease that is overexpressed in tumor cells. Radioimmunoconjugates (RICs) composed of CTSB-recognizing chelating agents are expected to increase the molecular weights of their radiometabolites by forming conjugates with CTSB in cells, resulting in their improved retention in tumor cells. We designed a novel CTSB-recognizing trifunctional chelating agent, azide-[111In]In-DOTA-CTSB-substrate ([111In]In-ADCS), to synthesize a RIC, trastuzumab-[111In]In-ADCS ([111In]In-TADCS), and evaluated its utility to improve tumor retention of the RIC. [111In]In-ADCS and [111In]In-TADCS were synthesized with satisfactory yield and purity. [111In]In-ADCS was markedly stable in murine plasma until 96 h postincubation. [111In]In-ADCS showed binding to CTSB in vitro, and the conjugation was blocked by the addition of CTSB inhibitor. In the internalization assay, [111In]In-TADCS exhibited high-level retention in SK-OV-3 cells, indicating the in vitro utility of the CTSB-recognizing unit. In the biodistribution assay, [111In]In-TADCS showed high-level tumor accumulation, but the retention was hardly improved. In the first attempt to combine a CTSB-recognizing unit and RIC, these findings show the fundamental properties of the CTSB-recognizing trifunctional chelating agent to improve tumor retention of RICs.

Myricetin ameliorates the severity of pancreatitis in mice by regulating cathepsin B activity and inflammatory cytokine production.

Cathepsin B (CTSB) and inflammatory cytokines are critical in initiating and developing pancreatitis. Calcineurin, a central calcium (Ca2+)-responsive signaling molecule, mediates acinar cell death and inflammatory responses leading to pancreatitis. However, the detailed mechanisms for regulating CTSB activity and inflammatory cytokine production are unknown. Myricetin (MC) exhibits various biological activities, including anti-inflammatory effects. Here, we aimed to investigate MC effects on pancreatitis and the underlying mechanisms. Prophylactic and therapeutic MC treatment ameliorated the severity of cerulein-, L-arginine-, and PDL-induced acute pancreatitis (AP). The inhibition of CTSB activity by MC was mediated via decreased calcineurin activity and macrophage infiltration, not neutrophils infiltration, into the pancreas. Additionally, calcineurin activity inhibition by MC prevented the phosphorylation of Ca2+/CaM-dependent protein kinase kinase 2 (CaMKK2) during AP, resulting in the inhibition of CaMKIV phosphorylation and adenosine monophosphate-activated protein kinase (AMPK) dephosphorylation. Furthermore, MC reduced nuclear factor-κB activation by modulating the calcineurin-CaMKIV-IKKα/ß-Iκ-Bα and calcineurin-AMPK-sirtuin1 axes, resulting in reduced production of tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6. Our results showed that MC alleviated AP severity by inhibiting acinar cell death and inflammatory responses, suggesting that MC as a calcineurin and CaMKK2 signaling modulator may be a potential treatment for AP.

MiR-223 enhances lipophagy by suppressing CTSB in microglia following lysolecithin-induced demyelination in mice.

BACKGROUND: Lipid droplet (LD)-laden microglia is a key pathological hallmark of multiple sclerosis. The recent discovery of this novel microglial subtype, lipid-droplet-accumulating microglia (LDAM), is notable for increased inflammatory factor secretion and diminished phagocytic capability. Lipophagy, the autophagy-mediated selective degradation of LDs, plays a critical role in this context. This study investigated the involvement of microRNAs (miRNAs) in lipophagy during demyelinating diseases, assessed their capacity to modulate LDAM subtypes, and elucidated the potential underlying mechanisms involved. METHODS: C57BL/6 mice were used for in vivo experiments. Two weeks post demyelination induction at cervical level 4 (C4), histological assessments and confocal imaging were performed to examine LD accumulation in microglia within the lesion site. Autophagic changes were observed using transmission electron microscopy. miRNA and mRNA multi-omics analyses identified differentially expressed miRNAs and mRNAs under demyelinating conditions and the related autophagy target genes. The role of miR-223 in lipophagy under these conditions was specifically explored. In vitro studies, including miR-223 upregulation in BV2 cells via lentiviral infection, validated the bioinformatics findings. Immunofluorescence staining was used to measure LD accumulation, autophagy levels, target gene expression, and inflammatory mediator levels to elucidate the mechanisms of action of miR-223 in LDAM. RESULTS: Oil Red O staining and confocal imaging revealed substantial LD accumulation in the demyelinated spinal cord. Transmission electron microscopy revealed increased numbers of autophagic vacuoles at the injury site. Multi-omics analysis revealed miR-223 as a crucial regulatory gene in lipophagy during demyelination. It was identified that cathepsin B (CTSB) targets miR-223 in autophagy to integrate miRNA, mRNA, and autophagy gene databases. In vitro, miR-223 upregulation suppressed CTSB expression in BV2 cells, augmented autophagy, alleviated LD accumulation, and decreased the expression of the inflammatory mediator IL-1ß. CONCLUSION: These findings indicate that miR-223 plays a pivotal role in lipophagy under demyelinating conditions. By inhibiting CTSB, miR-223 promotes selective LD degradation, thereby reducing the lipid burden and inflammatory phenotype in LDAM. This study broadens the understanding of the molecular mechanisms of lipophagy and proposes lipophagy induction as a potential therapeutic approach to mitigate inflammatory responses in demyelinating diseases.

Late-onset Krabbe disease presenting as spastic paraplegia - implications of GCase and CTSB/D.

OBJECTIVE: Krabbe disease (KD) is a multisystem neurodegenerative disorder with severe disability and premature death, mostly with an infancy/childhood onset. In rare cases of late-onset phenotypes, symptoms are often milder and difficult to diagnose. We here present a translational approach combining diagnostic and biochemical analyses of a male patient with a progressive gait disorder starting at the age of 44 years, with a final diagnosis of late-onset KD (LOKD). METHODS: Additionally to cerebral MRI, protein structural analyses of the ß-galactocerebrosidase protein (GALC) were performed. Moreover, expression, lysosomal localization, and activities of ß-glucocerebrosidase (GCase), cathepsin B (CTSB), and cathepsin D (CTSD) were analyzed in leukocytes, fibroblasts, and lysosomes of fibroblasts. RESULTS: Exome sequencing revealed biallelic likely pathogenic variants: GALC exons 11-17: 33 kb deletion; exon 4: missense variant (c.334A>G, p.Thr112Ala). We detected a reduced GALC activity in leukocytes and fibroblasts. While histological KD phenotypes were absent in fibroblasts, they showed a significantly decreased activities of GCase, CTSB, and CTSD in lysosomal fractions, while expression levels were unaffected. INTERPRETATION: The presented LOKD case underlines the age-dependent appearance of a mildly pathogenic GALC variant and its interplay with other lysosomal proteins. As GALC malfunction results in reduced ceramide levels, we assume this to be causative for the here described decrease in CTSB and CTSD activity, potentially leading to diminished GCase activity. Hence, we emphasize the importance of a functional interplay between the lysosomal enzymes GALC, CTSB, CTSD, and GCase, as well as between their substrates, and propose their conjoined contribution in KD pathology.

Disulfide bonds as a molecular switch of enzyme-activatable anticancer drug precise release for fluorescence imaging and enhancing tumor therapy.

Enzyme-activatable drug delivery systems have been developed for cancer diagnosis and therapy. However, targeted intracellular drug delivery is a challenge for precisely tumor imaging and therapy due to the increased stability of copolymer nanoparticles (NPs) is accompanied by a notable decrease in enzyme degradation. Herein, disulfide bond was designed as an enzyme-activatable molecular switch of SS-P(G2)2/DOX NPs. The copolymer NPs consists of polyvinylpyrrolidone (PVP) with disulfide bonds in the center and enzyme-degradable peptide dendrites (Phe-Lys) to form dendritic-linear-dendritic triblock copolymers (TBCs). The amphiphilic TBCs could be split into two identical amphiphilic diblock copolymers (DBCs) by glutathione (GSH) in cancer cells specifically while maintaining the same hydrophilic-lipophilic equilibrium. This structural transformation significantly reduced the stability of copolymer NPs and enhanced sensitivity of DOX release by cathepsin B-activated. Subsequently, the released DOX acted as an indicator of fluorescence imaging and chemotherapy drug for cancer cells. The polymeric NPs achieved excellent drug-loaded stability and prolonged blood circulation in vivo, and realized fluorescence imaging and specific cancer cell killing capabilities by responding to the overexpression of GSH and cathepsin B in tumor cells. Furthermore, the copolymer NPs demonstrated excellent blood compatibility and biosafety. Therefore, a novel strategy based on one tumor marker acting as the switch for another tumor microenvironment responsive drug delivery system could be designed for tumor intracellular imaging and chemotherapy.

Impact of Acute High-intensity Interval Training on Cortical Excitability, M1-related Cognitive Functions, and Myokines: A Randomized Crossover Study.

High-intensity interval training (HIIT) is a time-efficient, safe, and feasible exercise type that can be utilized across different ages and health status. This randomized cross-over study aimed to investigate the effect of acute HIIT on cortical excitability, M1-related cognitive functions, cognition-related myokines, brain-derived neurotrophic factor (BDNF), and Cathepsin B (CTSB). Twenty-three sedentary young adults (mean age: 22.78 years ± 2.87; 14 female) participated in a cross-over design involving two sessions: either 23 min of HIIT or seated rest. Before and after the sessions, cortical excitability was measured using transcranial magnetic stimulation, and M1-related cognitive functions were assessed by the n-back test and mental rotation test. Serum levels of BDNF and CTSB were assessed using the ELISA method before and after the HIIT intervention. We demonstrated that HIIT improved mental rotation and working memory, and increased serum levels of BDNF and CTSB, whereas cortical excitability did not change. Our findings provide evidence that one session of HIIT is effective on M1-related cognitive functions and cognition-related myokines. Future research is warranted to determine whether such findings are transferable to different populations, such as cognitively at-risk children, adults, and older adults, and to prescribe effective exercise programs.

Initiation of acute pancreatitis in mice is independent of fusion between lysosomes and zymogen granules.

The co-localization of the lysosomal protease cathepsin B (CTSB) and the digestive zymogen trypsinogen is a prerequisite for the initiation of acute pancreatitis. However, the exact molecular mechanisms of co-localization are not fully understood. In this study, we investigated the role of lysosomes in the onset of acute pancreatitis by using two different experimental approaches. Using an acinar cell-specific genetic deletion of the ras-related protein Rab7, important for intracellular vesicle trafficking and fusion, we analyzed the subcellular distribution of lysosomal enzymes and the severity of pancreatitis in vivo and ex vivo. Lysosomal permeabilization was performed by the lysosomotropic agent Glycyl-L-phenylalanine 2-naphthylamide (GPN). Acinar cell-specific deletion of Rab7 increased endogenous CTSB activity and despite the lack of re-distribution of CTSB from lysosomes to the secretory vesicles, the activation of CTSB localized in the zymogen compartment still took place leading to trypsinogen activation and pancreatic injury. Disease severity was comparable to controls during the early phase but more severe at later time points. Similarly, GPN did not prevent CTSB activation inside the secretory compartment upon caerulein stimulation, while lysosomal CTSB shifted to the cytosol. Intracellular trypsinogen activation was maintained leading to acute pancreatitis similar to controls. Our results indicate that initiation of acute pancreatitis seems to be independent of the presence of lysosomes and that fusion of lysosomes and zymogen granules is dispensable for the disease onset. Intact lysosomes rather appear to have protective effects at later disease stages.

Nature-Inspired Gallinamides Are Potent Antischistosomal Agents: Inhibition of the Cathepsin B1 Protease Target and Binding Mode Analysis.

Schistosomiasis, caused by a parasitic blood fluke of the genus Schistosoma, is a global health problem for which new chemotherapeutic options are needed. We explored the scaffold of gallinamide A, a natural peptidic metabolite of marine cyanobacteria that has previously been shown to inhibit cathepsin L-type proteases. We screened a library of 19 synthetic gallinamide A analogs and identified nanomolar inhibitors of the cathepsin B-type protease SmCB1, which is a drug target for the treatment of schistosomiasis mansoni. Against cultured S. mansoni schistosomula and adult worms, many of the gallinamides generated a range of deleterious phenotypic responses. Imaging with a fluorescent-activity-based probe derived from gallinamide A demonstrated that SmCB1 is the primary target for gallinamides in the parasite. Furthermore, we solved the high-resolution crystal structures of SmCB1 in complex with gallinamide A and its two analogs and describe the acrylamide covalent warhead and binding mode in the active site. Quantum chemical calculations evaluated the contribution of individual positions in the peptidomimetic scaffold to the inhibition of the target and demonstrated the importance of the P1' and P2 positions. Our study introduces gallinamides as a powerful chemotype that can be exploited for the development of novel antischistosomal chemotherapeutics.

Group A Streptococcus induces lysosomal dysfunction in THP-1 macrophages.

The human-specific bacterial pathogen group A Streptococcus (GAS) is a significant cause of morbidity and mortality. Macrophages are important to control GAS infection, but previous data indicate that GAS can persist in macrophages. In this study, we detail the molecular mechanisms by which GAS survives in THP-1 macrophages. Our fluorescence microscopy studies demonstrate that GAS is readily phagocytosed by macrophages, but persists within phagolysosomes. These phagolysosomes are not acidified, which is in agreement with our findings that GAS cannot survive in low pH environments. We find that the secreted pore-forming toxin Streptolysin O (SLO) perforates the phagolysosomal membrane, allowing leakage of not only protons but also large proteins including the lysosomal protease cathepsin B. Additionally, GAS recruits CD63/LAMP-3, which may contribute to lysosomal permeabilization, especially in the absence of SLO. Thus, although GAS does not inhibit fusion of the lysosome with the phagosome, it has multiple mechanisms to prevent proper phagolysosome function, allowing for persistence of the bacteria within the macrophage. This has important implications for not only the initial response but also the overall functionality of the macrophages, which may lead to the resulting pathologies in GAS infection. Our data suggest that therapies aimed at improving macrophage function may positively impact patient outcomes in GAS infection.

Cinnamaldehyde hydrazone derivatives as potential cathepsin B inhibitors: parallel in-vitro investigation in liver and cerebrospinal fluid.

The emergence of cathepsins as a potential target for anticancer drugs has led to extensive research in the development of their inhibitors. In the present study, we designed, synthesized, and characterized several cinnamaldehyde schiff bases employing diverse hydrazines, as potential cathepsin B inhibitors. The parallel studies on cathepsin B isolated from liver and cerebrospinal fluid unveiled the significance of the synthesized compounds as cathepsin B inhibitors at nanomolar concentrations. The compound, 7 exhibited the highest inhibition of 83.48 % and 82.96 % with an IC50 value of 0.06 nM and 0.09 nM for liver and cerebrospinal fluid respectively. The inhibitory potential of synthesized compounds has been extremely effective in comparison to previous reports. With the help of molecular docking studies using iGEMDOCK software, we found that the active site -CH2SH group is involved in the case of α-N-benzoyl-D, l-arginine-b-naphthylamide (BANA), curcumin 2, 3, 6, and 7. For toxicity prediction, ADMET studies were conducted and the synthesized compounds emerged to be non-toxic. The results obtained from the in vitro studies were supported with in silico studies. The synthesized cinnamaldehyde schiff bases can be considered promising drug candidates in conditions with elevated cathepsin B levels.

New strategy to treat spinal cord injury: Nafamostat mesilate suppressed NLRP3-mediated pyroptosis during acute phase.

Spinal cord injury (SCI) is a devastating condition for which effective clinical treatment is currently lacking. During the acute phase of SCI, myriad pathological changes give rise to subsequent secondary injury. The results of our previous studies indicated that treating rats post-SCI with nafamostat mesilate (NM) protected the blood-spinal cord barrier (BSCB) and exerted an antiapoptotic effect. However, the optimal dosage for mice with SCI and the underlying mechanisms potentially contributing to recovery, especially during the acute phase of SCI, have not been determined. In this study, we first determined the optimal dosage of NM for mice post-SCI (5 mg/kg/day). Subsequently, our RNA-seq findings revealed that NM has the potential to inhibit pyroptosis after SCI. These findings were further substantiated by subsequent Western blot (WB) and Immunofluorescence (IF) analyses in vivo. These results indicate that NM can alleviate NLRP3 (NOD-like receptor thermal protein domain associated protein 3)-mediated pyroptosis by modulating the NF-κB signaling pathway and reducing the protein expression levels of NIMA-related kinase 7 (NEK7) and cathepsin B (CTSB). In vitro experimental results supported our in vivo findings, revealing the effectiveness of NM in suppressing pyroptosis induced by adenosine triphosphate (ATP) and lipopolysaccharide (LPS) in BV2 cells. These results underscore the potential of NM to regulate NLRP3-mediated pyroptosis following SCI. Notably, compared with other synthetic compounds, NM exhibits greater versatility, suggesting that it is a promising clinical treatment option for SCI.

Influence of stimulation frequency on brain-derived neurotrophic factor and cathepsin-B production in healthy young adults.

Electrical muscle stimulation (EMS) has been shown to stimulate the production of myokines (i.e., brain-derived neurotrophic factor (BDNF)), but the most effective EMS parameters for myokine production have not been fully elucidated. The purpose of this study was to quantify the optimal EMS frequency for stimulating myokine production. This study included sixteen young adults (male, n = 13, age = 27.3 ± 5.5 years). Participants underwent four EMS interventions (20 min each) with the following conditions: (1) 4 Hz, (2) 20 Hz, (3) 80 Hz, and (4) control (no intervention). Blood samples were obtained before and immediately after EMS. For the control condition, blood samples were taken before and after 20 min of quiet sitting. BDNF and cathepsin-B levels were analyzed in serum. Compared to preintervention levels, stimulation at 20 Hz resulted in significantly greater postintervention cathepsin-B and BDNF levels (p < 0.01). On the other hand, the control condition did not result in a significant change between pre- and posttreatment. Furthermore, stimulation at 20 Hz caused significantly larger increases in cathepsin-B and BDNF levels than stimulation at 4-80 Hz or the control condition (p < 0.05). In conclusion, stimulation at 20 Hz effectively causes a robust cathepsin-B and BDNF response. Based on these results, we suggest a new strategy for rehabilitation of people with neurological disorders.

Specific photodamage on HT-29 cancer cells leads to endolysosomal failure and autophagy blockage by cathepsin depletion.

Endolysosomes perform a wide range of cellular functions, including nutrient sensing, macromolecule digestion and recycling, as well as plasma membrane repair. Because of their high activity in cancerous cells, endolysosomes are attractive targets for the development of novel cancer treatments. Light-activated compounds termed photosensitizers (PS) can catalyze the oxidation of specific biomolecules and intracellular organelles. To selectively damage endosomes and lysosomes, HT-29 colorectal cancer cells were incubated with nanomolar concentrations of meso-tetraphenylporphine disulfonate (TPPS2a), an amphiphilic PS taken up via endocytosis and activated by green light (522 nm, 2.1 J.cm-1). Several cellular responses were characterized by a combination of immunofluorescence and immunoblotting assays. We showed that TPPS2a photosensitization blocked autophagic flux without extensive endolysosomal membrane rupture. Nevertheless, there was a severe functional failure of endolysosomes due to a decrease in CTSD (cathepsin D, 55%) and CTSB (cathepsin B, 52%) maturation. PSAP (prosaposin) processing (into saposins) was also considerably impaired, a fact that could be detrimental to glycosphingolipid homeostasis. Therefore, photosensitization of HT-29 cells previously incubated with a low concentration of TPPS2a promotes endolysosomal dysfunction, an effect that can be used to improve cancer therapies.

Design, synthesis, and biological evaluation of cathepsin B cleavage albumin-binding SN38 prodrug in breast cancer.

Here, we introduce a novel and effective approach utilizing a cathepsin B cleavage albumin-binding SN38 prodrug specifically designed for the treatment of metastatic breast cancer. Termed Mal-va-mac-SN38, our prodrug exhibits a unique ability to rapidly and covalently bind with endogenous albumin, resulting in the formation of HSA-va-mac-SN38. This prodrug demonstrates exceptional stability in human plasma. Importantly, HSA-va-mac-SN38 showcases an impressive enhancement in cellular uptake by 4T1 breast cancer cells, primarily facilitated through caveolin-mediated endocytosis. Intriguingly, the release of the active SN38, is triggered by the enzymatic activity of cathepsin B within the lysosomal environment. In vivo studies employing a lung metastasis 4T1 breast cancer model underscore the potency of HSA-va-mac-SN38. Histological immunohistochemical analyses further illuminate the multifaceted impact of our prodrug, showcasing elevated levels of apoptosis, downregulated expression of matrix metalloproteinases, and inhibition of angiogenesis, all critical factors contributing to the anti-metastatic effect observed. Biodistribution studies elucidate the capacity of Mal-va-mac-SN38 to augment tumor accumulation through covalent binding to serum albumin, presenting a potential avenue for targeted therapeutic interventions. Collectively, our findings propose a promising therapeutic avenue for metastatic breast cancer, through the utilization of a cathepsin B-cleavable albumin-binding prodrug.