Curcumin as inhibitor of mammalian Cathepsin B, Cathepsin H, acid phosphatase and alkaline phosphatase: a correlation with pharmacological activities

Development of potential cathepsin B inhibitors: Synthesis of new bithiazole derivatives, in vitro studies supported with theoretical docking studies

Cysteine cathepsins play a crucial role in cancer, inflammation, and the regulation of degenerative processes such as apoptosis, making them significant targets in drug development. In this study, we designed, synthesized, and characterized sixteen novel bi-thiazole derivatives, confirmed by 1H NMR, 13C NMR, HRMS, and X-ray analysis, which demonstrated significant therapeutic potential as inhibitors of cathepsin B. The synthesized thiazoles showed % inhibition in the range of 59.11-77.32, out of which bis-methoxyphenyl derivative 8k showed the highest inhibition of 77.32 % with IC50 and ki values of 1.04 nM and 0.52 nM, respectively. Methoxy-containing derivatives 8c, 8g, 8i, 8j, 8l, and 8o showed improved inhibition over methyl and chloro. In silico studies of the new bis-thiazole compounds at cathepsin B active sites supported the in vitro findings, indicating that the synthesized bis-thiazole esters are promising therapeutic candidates for conditions involving elevated cathepsin B levels.

Novel thiazolotriazole and triazolothiadiazine scaffolds as selective tumor associated carbonic anhydrase inhibitors endowed with cathepsin B inhibition

The present research focused on the tail-approach synthesis of novel extended thiazolotriazoles (8a-8j) and triazolothiadiazines (11a-11j) including aminotriazole intermediate 10. After successful synthesis, all the compounds were evaluated for their inhibition potential against cytosolic isoforms of human carbonic anhydrase (hCA I, II), tumor-linked transmembrane isoforms (hCA IX, XII), and cathepsin B. As per the inhibition data, the newly synthesized compounds showed poor inhibition against hCA I. Many of the compounds showed effective inhibition toward hCA IX and/or XII in low nanomolar concentration. Despite the strong to moderate inhibition of hCA II by these compounds, more than half of them demonstrated better inhibition against hCA IX and/or XII, comparatively. Further, insights of CA inhibition data of these extended analogs and their comparison with earlier reported thiazolotriazole and triazolothiadiazine derivatives might help in the rational design of novel potent and selective hCA IX and XII inhibitors. The novel compounds were also found to possess anti-cathepsin B potential at a low concentration of 10-7 M. Broadly, compounds of series 11a-11j presented more effective inhibition against cathepsin B than their counterparts in series 8a-8j. Moreover, these in vitro results with respect to cathepsin B inhibition were also supported by the in silico insights obtained via molecular modeling studies.

Benzenesulfonamides functionalized with triazolyl-linked pyrazoles possess dual cathepsin B and carbonic anhydrase inhibitory action

The design and synthesis of a library of 21 novel benzenesulfonamide-bearing 3-functionalized pyrazole-linked 1,2,3-triazole derivatives as dual inhibitors of cathepsin B and carbonic anhydrase enzymes are reported. The target 1,2,3-triazole-linked pyrazolic esters (16) were synthesized by the condensation of 1,2,3-triazolic diketo esters with 4-hydrazinobenzenesulfonamide hydrochloride, and these were further converted into the corresponding carboxylic acid (17) and carboxamide (18) analogs. The synthesized compounds were assayed in vitro for their inhibition potential against human carbonic anhydrase (hCA) isoforms I, II, IX, and XII. They were found to be potent inhibitors at the low nanomolar level against the cancer-related hCA IX and XII and to be selective towards the cytosolic isoform hCA I. The physiologically important isoform hCA II was potently inhibited by all the newly synthesized compounds showing KI values ranging between 0.8 and 561.5 nM. The ester derivative 16c having 4-fluorophenyl (KI = 5.2 nM) was the most potent inhibitor of hCA IX, and carboxamide derivative 18b (KI = 2.2 nM) having 4-methyl substituted phenyl was the most potent inhibitor of hCA XII. The newly synthesized compounds exhibited potent cathepsin B inhibition at 10-7 M concentration. In general, the carboxamide derivatives (18) showed higher % inhibition as compared with the corresponding ester derivatives (16) and carboxylic acid derivatives (17) for cathepsin B. The interactions of the target compounds with the active sites of cathepsin B and CA were studied through molecular docking studies. Further, the in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of the target compounds were also studied.

Multimodal Blockade of the Renin-Angiotensin System in the Treatment of Cancer in Dogs Has Mild Adverse Effects in Some Dogs

The renin-angiotensin system (RAS) is increasingly being recognized to play a role in the tumor microenvironment, promoting tumor growth. Studies blocking a single part of the RAS have shown mixed results, possibly due to the existence of different bypass pathways and redundancy within the RAS. As such, multimodal blockade of the RAS has been developed to exert more complete inhibition of the RAS. The aim of the present study was to assess the safety of multimodal RAS blockade in dogs. Five dogs (four with appendicular osteosarcoma, one with oral malignant melanoma) were treated with atenolol, benazepril, curcumin, meloxicam, and metformin. The dogs underwent clinical examination, blood pressure measurement, and hematology and serum biochemistry tests performed at 0, 1, 3, 6, 9, and 12 weeks, then every 3 months thereafter. End-of-life decisions were made by the owners. None of the dogs developed hypotension. One dog had intermittent vomiting during the 64 weeks it was on the trial. One dog had a one-off increase in serum SDMA(symmetrical dimethylarginine) concentration. Dogs were euthanized at weeks 3 (osteosarcoma), 10 (osteosarcoma), 17 (osteosarcoma), and 26 (oral malignant melanoma), and one dog was still alive at the end of the trial at 64 weeks (osteosarcoma). This is the first assessment of multimodal blockade of the RAS in dogs, and the results suggest it causes only mild adverse effects in some animals. The efficacy of the treatment was not assessed due to the small number of dogs. This pilot study allows for future larger studies assessing multimodal RAS blockade for the treatment of canine cancer.

Mechanisms of polyphenols on quality control of aquatic products in storage: A review

Aquatic products are easily spoiled during storage due to oxidation, endogenous enzymes, and bacteria. At the same time, compared with synthetic antioxidants, based on the antibacterial and antioxidant mechanism of biological agents, the development of natural, nontoxic, low-temperature, better-effect green biological preservatives is more acceptable to consumers. The type and molecular structure of polyphenols affect their antioxidant and antibacterial effectiveness. This review will describe how they achieve their antioxidant and antibacterial effects. And the recent literature on the mechanism and application of polyphenols in the preservation of aquatic products was updated and summarized. The conclusion is that in aquatic products, polyphenols alleviate lipid oxidation, protein degradation and inhibit the growth and reproduction of microorganisms, so as to achieve the effect of storage quality control. And put forward suggestions on the application of the research results in aquatic products. We hope to provide theoretical support for better exploration of the application of polyphenols and aquatic product storage.

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.

Novel 1,2,4-triazoles as selective carbonic anhydrase inhibitors showing ancillary anticathepsin B activity

Background: Exploration of the multi-target approach considering both human carbonic anhydrase (hCA) IX and XII and cathepsin B is a promising strategy to target cancer. Methodology & Results: 22 novel 1,2,4-triazole derivatives were synthesized and evaluated for their inhibition efficacy against hCA I, II, IX, XII isoforms and cathepsin B. The compounds demonstrated effective inhibition against hCA IX and/or XII isoforms with considerable selectivity over off-target hCA I/II. All compounds presented significant anticathepsin B activities at a low concentration of 10-7 M and in vitro results were also supported by the molecular modeling studies. Conclusion: Insights of present study can be utilized in the rational design of effective and selective hCA IX and XII inhibitors capable of inhibiting cathepsin B.

Inhibition effect of epicatechin gallate on acid phosphatases from rainbow trout (Oncorhynchus mykiss) liver by multispectral and molecular docking

Inhibition of acid phosphatase, which significantly contributes to inosine 5'-monophosphate (IMP) degradation, is crucial for preventing flavor deterioration of aquatic products during storage. In this study, the inhibitory effect of epicatechin gallate (ECG) on the activity of acid phosphatase isozymes (ACPI and ACPII) was analyzed using inhibition kinetics, fluorescence spectroscopy, isothermal titration calorimetry, and molecular simulation. ACPI and ACPII with molecular weights of 59.5 and 37.3 kDa, respectively, were purified from rainbow trout liver. ECG reversibly inhibited ACPI and ACPII activities via mixed-type inhibition, with half maximal inhibitory concentration (IC50) of 0.24 ± 0.01 mmol/L and 0.27 ± 0.03 mmol/L, respectively. Fluorescence spectra indicated that ECG statically quenched the intrinsic fluorescence of ACPI and ACPII. ECG could spontaneously bind to ACPI and ACPII through hydrogen bonding and van der Waals forces and exhibited a higher affinity for ACPI than for ACPII. In addition, molecular dynamic simulation revealed that ECG-ACPI and ECG-ACPII complexes were relatively stable during the entire simulation process. Our findings provide a theoretical basis for the use of ECG as an inhibitor of ACP to improve the flavor of aquatic products.

1,2,3-Triazole-based esters and carboxylic acids as nonclassical carbonic anhydrase inhibitors capable of cathepsin B inhibition

Herein, we report the design and synthesis of a library of 28 new 1,2,3-triazole derivatives bearing carboxylic acid and ester moieties as dual inhibitors of carbonic anhydrase (CA) and cathepsin B enzymes. The synthesised compounds were assayed in vitro for their inhibition potential against four human CA (hCA) isoforms, I, II, IX and XII. The carboxylic acid derivatives displayed low micromolar inhibition against hCA II, IX and XII in contrast to the ester derivatives. Most of the target compounds showed poor inhibition against the hCA I isoform. 4-Fluorophenyl appended carboxylic acid derivative 6c was found to be the most potent inhibitor of hCA IX and hCA XII with a KI value of 0.7 μM for both the isoforms. The newly synthesised compounds showed dual inhibition towards CA as well as cathepsin B. The ester derivatives exhibited higher % inhibition at 10-7  M concentration as compared with the corresponding carboxylic acid derivatives against cathepsin B. The results from in silico studies of the target compounds with the active site of cathepsin B were found in good correlation with the in vitro results. Moreover, two compounds, 5i and 6c, showed cytotoxic activity against A549 lung cancer cells, with IC50 values lower than 100 μM.

Potent inhibitors of tumor associated carbonic anhydrases endowed with cathepsin B inhibition

Twenty-one novel extended analogs of acetazolamide were synthesized and screened in vitro for their inhibition efficacy against human carbonic anhydrase (hCA) isoforms I, II, IX, XII, and cathepsin B. The majority of the compounds were found to be effective inhibitors of tumor-associated hCA IX and XII, and poor inhibitors of cytosolic hCA I. Despite the strong to moderate inhibition potential possessed by these compounds toward another cytosolic isoform hCA II, some of them demonstrated better potency against hCA IX and/or XII isoforms as compared to hCA II. Four compounds (11f, 11g, 12c, and 12g) effectively inhibited hCA IX and/or XII isoforms with considerable selectivity over the off-targets hCA I and II. Interestingly, five compounds, including 11f, 11g, 12c, 12d, and 12g, inhibited hCA IX even better than the clinically used acetazolamide. Some of the novel synthesized compounds exhibited higher anti-cathepsin B potential than acetazolamide, with % inhibition of around 50%, at a concentration of 10-7  M. Further, two compounds (12g and 12c) that showed effective and selective inhibition activity profiles against hCA IX and XII were additionally found to be effective inhibitors of cathepsin B.

Keto-bridged dual triazole-linked benzenesulfonamides as potent carbonic anhydrase and cathepsin B inhibitors

Background: Inhibition of human carbonic anhydrase (hCA) isoforms IX and XII with concurrent inhibition of cathepsin B is a promising approach for targeting cancers. Methods/results: 28 keto-bridged dual triazole-containing benzenesulfonamides were synthesized and tested, following the multitarget approach, for their efficacy as inhibitors of cathepsin B and hCA isoforms (I, II, IX, XII). The synthesized compounds showed excellent inhibition of CA isoforms (IX and XII) and cathepsin B. Compound 8i exhibited better and more selective inhibition of the cancer-associated isoform hCA IX as compared with acetazolamide (reference drug) and SLC-0111 (potent lead as carbonic anhydrase inhibitor). Molecular docking studies were also carried out. Conclusion: The present work gives important generalizations for the development of isoform-selective hCA inhibitors endowed with anti-cathepsin properties.

Differential binding of piperine & curcumin with modified cellulose, alginate and pectin supports: In-vitro & in-silico studies

Use of natural polymer in the development of Drug Delivery Systems (DDS) has greatly increased in recent past because of their biocompatible, non-allergic and biodegradable nature. Natural polymers are usually hydrophilic supports, so in order to be a carrier of a hydrophobic drug their nature needs to be changed. Each developed system behaves differently towards different drugs in terms of loading and sustained release of the drug as well. In the present work we report differential binding of piperine & curcumin with cetyltrimethylammonium bromide (CTAB) modified cellulose, alginate and pectin. Difference in interaction between the piperine and curcumin with supports has been visualized using in-vitro as well as in-silico studies. Initial results obtained after in-silico studies have been validated via time dependent anti-trypsin, serum protein binding, anti-cathepsin, anti-oxidant, and anti-α-amylase activities. FT-IR, SEM, fluorescence and Particle size have been used to characterize the piperine loaded on CTAB-modified polymeric supports.

Expression of Cathepsins B, D, and G in Extracranial Arterio-Venous Malformation

Objectives: We have previously identified a population of cells that expressed stemness-associated markers in extracranial arterio-venous malformation (AVM) and demonstrated expression of cathepsins B, D, and G on embryonic stem cell (ESC)-like populations in other vascular anomalies. This study investigated the expression of cathepsins B, D, and G, and their localization in relation to this primitive population in extracranial AVM.

Methods: Immunohistochemical staining was performed on AVM tissue samples from 13 patients to demonstrate expression of cathepsins B, D, and G. Western blotting was performed on four AVM tissue samples and three AVM-derived primary cell lines to confirm protein expression of cathepsins B and D proteins. RT-qPCR was performed on three AVM-derived primary cell lines to demonstrate transcript expression of cathepsins B, D, and G. Enzymatic activity assays were performed on three AVM-derived primary cell lines to investigate if cathepsins B and D were active. Localization of the cathepsins was investigated using immunofluorescence dual-staining of the cathepsins with the ESC markers OCT4 and SOX2, and mast cells marker chymase on two of the 13 AVM tissue samples.

Results: Immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 13 AVM tissue samples. Western blotting showed expression of cathepsins B and D proteins in all four AVM tissue samples and all three AVM-derived primary cell lines. RT-qPCR demonstrated transcripts of cathepsins B, D, and G in all three AVM-derived primary cell lines. Enzymatic activity assays showed that cathepsins B and D were active. Immunofluorescence staining showed expression of cathepsins B and D on the OCT4+/SOX2+ endothelium and media of the lesional vessels and cells within the stroma in AVM nidus. Cathepsin G was expressed on the chymase+ phenotypic mast cells.

Conclusions: This study demonstrated the novel finding of the expression of cathepsins B, D, and G in AVM. Cathepsins B and D were expressed by the primitive population, and cathepsin G was localized to mast cells, within the AVM nidus.

Phenolic compounds disrupt spike-mediated receptor-binding and entry of SARS-CoV-2 pseudo-virions

In the pursuit of suitable and effective solutions to SARS-CoV-2 infection, we investigated the efficacy of several phenolic compounds in controlling key cellular mechanisms involved in its infectivity. The way the SARS-CoV-2 virus infects the cell is a complex process and comprises four main stages: attachment to the cognate receptor, cellular entry, replication and cellular egress. Since, this is a multi-part process, it creates many opportunities to develop effective interventions. Targeting binding of the virus to the host receptor in order to prevent its entry has been of particular interest. Here, we provide experimental evidence that, among 56 tested polyphenols, including plant extracts, brazilin, theaflavin-3,3'-digallate, and curcumin displayed the highest binding with the receptor-binding domain of spike protein, inhibiting viral attachment to the human angiotensin-converting enzyme 2 receptor, and thus cellular entry of pseudo-typed SARS-CoV-2 virions. Both, theaflavin-3,3'-digallate at 25 μg/ml and curcumin above 10 μg/ml concentration, showed binding with the angiotensin-converting enzyme 2 receptor reducing at the same time its activity in both cell-free and cell-based assays. Our study also demonstrates that brazilin and theaflavin-3,3'-digallate, and to a still greater extent, curcumin, decrease the activity of transmembrane serine protease 2 both in cell-free and cell-based assays. Similar pattern was observed with cathepsin L, although only theaflavin-3,3'-digallate showed a modest diminution of cathepsin L expression at protein level. Finally, each of these three compounds moderately increased endosomal/lysosomal pH. In conclusion, this study demonstrates pleiotropic anti-SARS-CoV-2 efficacy of specific polyphenols and their prospects for further scientific and clinical investigations.

Expression of Cathepsins B, D, and G in Microcystic Lymphatic Malformation

Background: This study investigated the expression and localization of cathepsins B, D, and G in relationship to the embryonic stem cell (ESC)-like population we have previously identified in microcystic lymphatic malformation (mLM). Methods and Results: Immunohistochemical staining demonstrated expression of cathepsins B, D, and G in cervicofacial mLM tissue samples from 11 patients. Immunofluorescence staining of two representative mLM samples showed localization of cathepsins B and D to the OCT4+ and the c-MYC+ cells on the endothelium of lesional vessels and the stroma, while cathepsin G was localized to the OCT4+/tryptase+ cells within the stroma. Transcript expression of cathepsins B, D, and G was confirmed using reverse transcription quantitative polymerase chain reaction (RT-qPCR; n = 5). Western blotting (n = 3) performed on the mLM tissue samples revealed protein expression of cathepsins B and D, which were demonstrated to be enzymatically active using enzymatic activity assays. Conclusion: This study demonstrated expression of cathepsins B and D by the ESC-like cells on the endothelium of lesional vessels and the stroma, while cathepsin G was localized to the OCT4+ phenotypic mast cells within the stroma of mLM.

In vitro and in silico evaluation of the inhibitory effect of a curcumin-based oxovanadium (IV) complex on alkaline phosphatase activity and bacterial biofilm formation

The scientific interest in the development of novel metal-based compounds as inhibitors of bacterial biofilm-related infections and alkaline phosphatase (ALP) deregulating effects is continuous and rising. In the current study, a novel crystallographically defined heteroleptic V(IV)-curcumin-bipyridine (V-Cur) complex with proven bio-activity was studied as a potential inhibitor of ALP activity and bacterial biofilm. The inhibitory effect of V-Cur was evaluated on bovine ALP, with two different substrates: para-nitrophenyl phosphate (pNPP) and adenosine triphosphate (ATP). The obtained results suggested that V-Cur inhibited the ALP activity in a dose-dependent manner (IC₅₀ = 26.91 ± 1.61 μM for ATP, IC₅₀ = 2.42 ± 0.12 μM for pNPP) exhibiting a mixed/competitive type of inhibition with both substrates tested. The evaluation of the potential V-Cur inhibitory effect on bacterial biofilm formation was performed on Gram (+) bacteria Staphylococcus aureus (S. aureus) and Gram (-) Escherichia coli (E. coli) cultures, and it positively correlated with inhibition of bacterial ALP activity. In silico study proved the binding of V-Cur at eukaryotic and bacterial ALP, and its interaction with crucial amino acids of the active sites, verifying complex's inhibitory potential. The findings suggested a specific anti-biofilm activity of V-Cur, offering a further dimension in the importance of metal complexes, with naturally derived products as biological ligands, as therapeutic agents against bacterial infections and ALP-associated diseases. KEY POINTS: • V-Cur inhibits bovine and bacterial alkaline phosphatases and bacterial biofilm formation. • Alkaline phosphatase activity correlates with biofilm formation. • In silico studies prove binding of the complex on alkaline phosphatase.

Curcumin, a traditional spice component, can hold the promise against COVID-19?

The severity of the recent pandemic and the absence of any specific medication impelled the identification of existing drugs with potential in the treatment of Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Curcumin, known for its pharmacological abilities especially as an anti-inflammatory agent, can be hypothesized as a potential candidate in the therapeutic regimen. COVID-19 has an assorted range of pathophysiological consequences, including pulmonary damage, elevated inflammatory response, coagulopathy, and multi-organ damage. This review summarizes the several evidences for the pharmacological benefits of curcumin in COVID-19-associated clinical manifestations. Curcumin can be appraised to hinder cellular entry, replication of SARS-CoV-2, and to prevent and repair COVID-19-associated damage of pneumocytes, renal cells, cardiomyocytes, hematopoietic stem cells, etc. The modulation and protective effect of curcumin on cytokine storm-related disorders are also discussed. Collectively, this review provides grounds for its clinical evaluation in the therapeutic management of SARS-CoV-2 infection.

A simple purification procedure of buffalo lung cathepsin H, its properties and influence of buffer constituents on the enzyme activity

BACKGROUND

Cathepsin H (E.C.3.4.22.16) belongs to a family of lysosomal cysteine protease which regulates diverse normal biological processes mainly in intracellular proteolysis.

METHODS

Purification of cathepsin H from an unstudied system i.e. buffalo lung has been achieved by a simple process developed after incorporating appropriate alteration in the available methods for isolation of the enzyme from other sources. The use of DEAE-Cellulose and SP-Sephadex C-50 helped in better and simultaneous separation of cathepsin B and H up to homogeneity.

RESULTS

The SDS-PAGE result showed buffalo cathepsin H to be a single-chain molecule having MW, NH2- and COOH- terminal residues of 25.4 kDa, Lys and Val respectively. The enzyme was a glycoprotein with pI of 6.2; it hydrolyzed Leu-NA (Vmax/Km = 301.6) as the most efficient substrate followed by Arg-NA, Arg-Arg-NA and BANA. Buffalo enzyme showed maximum activity at 36 °C, pH 6.75 and at a buffer concentration of 2 × 10-3 M.

CONCLUSION

Catheptic activity was found to be quite stable at least for 20-30 min between pH 4.5-7.0, buffer concentration of 1 × 10-2 to 4 × 10-2 M and the temperature resistance up to 36 °C. The effects of various substances present in the buffers routinely used for the assay of catheptic activity revealed that the activity of buffalo lung cathepsin H depends not only qualitatively but also quantitatively on the constituents of assay buffer.

GENERAL SIGNIFICANCE

This study seems to provide valuable information regarding the biochemistry of cathepsin H in general as well as influence of buffer constituents on enzyme activity and physiological role in particular.

Developments in drug design strategies for bromodomain protein inhibitors to target Plasmodium falciparum parasites

Introduction: Bromodomains (BRDs) bind to acetylated lysine residues, often on histones. The BRD proteins can contribute to gene regulation either directly through enzymatic activity or indirectly through recruitment of chromatin-modifying complexes or transcription factors. There is no evidence of direct orthologues of the Plasmodium falciparum BRD proteins (PfBDPs) outside the apicomplexans. PfBDPs are expressed during the parasite's life cycle in both the human host's blood and in the mosquito. PfBDPs could also prove to be promising targets for novel antimalarials, which are urgently required to address increasing drug resistance.Areas covered: This review discusses recent studies of the biology of PfBDPs, current target-based strategies for PfBDP inhibitor discovery, and different approaches to the important step of validating the specificity of hit compounds for PfBDPs.Expert opinion: The novelty of Plasmodium BRDs suggests that they could be targeted by selective compounds. Chemical series that showed promise in screens against human BRDs could be leveraged to create targeted compound libraries, as could hits from P. falciparum phenotypic screens. These targeted libraries and hits could be screened in target-based strategies aimed at discovery and optimization of novel inhibitors of PfBDPs. A key task for the field is to generate parasite assays to validate the hit compounds' specificity for PfBDPs.

Expression of Cathepsins B, D, and G by the Embryonic Stem Cell-Like Population within Human Keloid Tissues and Keloid-Derived Primary Cell Lines

BACKGROUND

The authors have previously shown that an embryonic stem cell-like population within keloid-associated lymphoid tissues in keloid lesions expresses components of the renin-angiotensin system that may be dysregulated. The authors hypothesized that cathepsins B, D, and G are present within the embryonic stem cell-like population in keloid lesions and contribute to bypass loops of the renin-angiotensin system.

METHODS

3,3'-Diaminobenzidine immunohistochemical staining for cathepsins B, D, and G was performed on formalin-fixed paraffin-embedded sections in keloid tissue samples of 11 patients. Immunofluorescence immunohistochemical staining was performed on three of these keloid tissue samples, by co-staining with CD34, tryptase, and OCT4. Western blotting, reverse transcription quantitative polymerase chain reaction, and enzyme activity assays were performed on five keloid tissue samples and four keloid-derived primary cell lines to investigate protein and mRNA expression, and functional activity, respectively.

RESULTS

3,3'-Diaminobenzidine immunohistochemical staining demonstrated expression of cathepsins B, D, and G in all 15 keloid tissue samples. Immunofluorescence immunohistochemical staining showed localization of cathepsins B and D to the endothelium of microvessels within the keloid-associated lymphoid tissues and localization of cathepsin G to the tryptase-positive perivascular cells. Western blotting confirmed semiquantitative levels of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines. Reverse transcription quantitative polymerase chain reaction showed quantitative transcriptional activation of cathepsins B and D in keloid tissue samples and keloid-derived primary cell lines and cathepsin G in keloid tissue samples. Enzyme activity assays demonstrated functional activity of cathepsins B and D.

CONCLUSION

Cathepsins B, D, and G are expressed by the embryonic stem cell-like population within the keloid-associated lymphoid tissues of keloid lesions and may act to bypass the renin-angiotensin system, suggesting a potential therapeutic target using renin-angiotensin system modulators and cathepsin inhibitors.

Inhibitory effect of curcuminoid pretreatments on endogenous dentin proteases

The aim of this study was to evaluate the effect of curcuminoids on the dentin endogenous protease activity. Demineralized dentin were pretreated with 50 or 100 µM of three different curcuminoids for 60 s and incubated up to 3 months. Untreated beams served as controls. Dry dentin mass was measured after incubation. Aliquots were analyzed for the quantity of ICTP and CTX releases for MMP and cathepsin-K mediated degradation, respectively. The effect of curcuminoids on matrix-bound MMP and soluble rhMMP-9 were measured using an activity assay. Data were subjected to repeated-measures-ANOVA (α=0.05). Gelatinolytic activity was analyzed using zymography. ICTP and CTX release and dry mass loss of curcuminoid-treated groups were significantly lower than the control. Inhibition of rhMMP-9 varied from 29-49% among curcumonoid-treated groups, whereas no inhibition was observed at untreated control (p>0.05). Results were confirmed by zymography. The study showed that the pretreatment of dentin matrices by curcuminoids decreases endogenous protease activity-mediated degradation in dentin.

Expression and Localization of Cathepsins B, D, and G in Dupuytren's Disease

BACKGROUND

The pathogenesis of Dupuytren's disease (DD) remains unclear. An embryonic stem cell (ESC)-like population in the endothelium of the microvessels around tissues that expresses components of the renin-angiotensin system (RAS) has been reported. This study investigated if this primitive population expresses cathepsins B, D, and G, that contribute to RAS bypass loops.

METHODS

3,3-Diaminobenzidine immunohistochemical (IHC) staining for cathepsins B, D, and G was performed on sections of formalin-fixed paraffin-embedded DD cords (n = 10) and nodules (n = 10). Immunofluorescence IHC staining was utilized to demonstrate co-expression of these cathepsins with ESC markers. Protein and gene expression of these cathepsins was investigated in snap-frozen DD cords (n = 3) and nodules (n = 3) by Western blotting and NanoString analysis, respectively. Enzymatic activity of these cathepsins was investigated by enzymatic activity assays.

RESULTS

3,3-Diaminobenzidine IHC staining demonstrated expression of cathepsins B, D, and G in DD cords and nodules. Gene expression of cathepsins B, D, and G was confirmed by NanoString analysis. Western blotting confirmed expression of cathepsins B and D, but not cathepsin G. Immunofluorescent IHC staining demonstrated high abundance of cathepsins B and D on the OCT4+/angiotensin converting enzyme+ endothelium and the smooth muscle layer of the microvessels. Cathepsin G was localized to trypase+ cells within the stroma in DD cords and nodules with limited expression on the microvessels. Enzyme activity assays demonstrated functional activity of cathepsins B and D.

CONCLUSIONS

Cathepsins B, D, and G were expressed in the DD tissues, with cathepsins B and D localized to the primitive population in the endothelium of the microvessels, whereas cathepsin G was localized to phenotypic mast cells, suggesting the presence of bypass loops for the RAS.