UNASSIGNED: Cysteine proteases are involved in a broad range of biological functions, ranging from extracellular matrix turnover to immunity. Playing an important role in the onset and progression of several diseases, including cancer, immune-related and neurodegenerative disease, viral and parasitic infections, cysteine proteases represent an attractive drug target for the development of therapeutic tools.
UNASSIGNED: Recent scientific and patent literature focusing on the design and study of cysteine protease inhibitors with potential therapeutic application has been reviewed.
UNASSIGNED: The discovery of a number of effective structurally diverse cysteine protease inhibitors opened up new challenges and opportunities for the development of therapeutic tools. Mechanistic studies and the availability of X-ray crystal structures of some proteases, alone and in complex with inhibitors, provide crucial information for the rational design and development of efficient and selective cysteine protease inhibitors as preclinical candidates for the treatment of different diseases.

Cathepsins are one of the most abundant proteases within the lysosomes with diverse physiological effects ranging from immune responses, cell death and intracellular protein degradation. Cathepsins are involved in extracellular and systemic functions such as systemic inflammation and extracellular matrix degradation. Ischemia reperfusion (IR) injury is responsible for numerous diseases including myocardial infarction, acute kidney injury, stroke and acute graft failure after transplant surgery. Inflammation plays a major role in the reperfusion phase of IR injury and previous research has shown that cathepsins are key mediators of the inflammation cascade as well as apoptosis. Taken together, cathepsins modulation could provide potential therapeutic approaches to attenuate IR injury. The present review summarized the current understanding of various cathepsin subtypes, their major physiologic functions, their roles in multi‑organ IR injury and detailed selective cathepsin inhibitors with therapeutic potential.

Cathepsins (CTSs) are multifunctional proteins that can play prominent roles in cancer progression and metastasis. In this systematic review, we compared the prognosis of CTS subtypes overexpression in leukemia and solid tumors, and investigated the effect of different factors on CTS prognosis. We systematically searched published articles indexed in PubMed, Scopus, Cochrane library, ISI Web of Science, and EmBase databases from February 2000 until January 2020. Among the selected leukemia and solid tumors studies, overexpression of CTS subtypes in newly diagnosed and treated patients were with poor prognosis in 43 studies (79.6%) and with good prognosis in 9 studies (16.6%). However, there were 2 studies (3.8%) with either good or poor prognosis, depending on conditions and caner stage and host cell. The relation between CTS and human leukocyte antigen (HLA) in leukemia and solid tumors was mentioned in 7 studies (13%). Overexpression of CTS subtypes in all new case patients had contributed to the induction of poor prognosis. It seems that CTS subtypes, based on the type of cancer and its stage, the type of host cells, and the probable relation with HLA, breed good or poor prognosis in patients with cancer. Therefore, monitoring the overexpression of CTS subtypes and determining the effect of each of these factors on CTS prognosis could be helpful in predicting cancer prognosis both in newly diagnosed or under treatment patients. They could also be useful in finding ways for improving the efficiency of contemporary therapeutic strategies in various types of leukemia and solid tumors.

Keloid disorder (KD) is a fibroproliferative condition characterized by excessive dermal collagen deposition in response to wounding and/or inflammation of the skin. Despite intensive research, treatment for KD remains empirical and unsatisfactory. Activation of the renin-angiotensin system (RAS) leads to fibrosis in various organs through its direct effect and the resultant hypertension, and activation of the immune system. The observation of an increased incidence of KD in dark-skinned individuals who are predisposed to vitamin D deficiency (VDD) and hypertension, and the association of KD with hypertension and VDD, all of which are associated with an elevated activity of the RAS, provides clues to the pathogenesis of KD. There is increasing evidence implicating embryonic-like stem (ESC) cells that express ESC markers within keloid-associated lymphoid tissues (KALTs) in keloid lesions. These primitive cells express components of the RAS, cathepsins B, D, and G that constitute bypass loops of the RAS, and vitamin D receptor (VDR). This suggests that the RAS directly, and through signaling pathways that converge on the RAS, including VDR-mediated mechanisms and the immune system, may play a critical role in regulating the primitive population within the KALTs. This review discusses the role of the RAS, its relationship with hypertension, vitamin D, VDR, VDD, and the immune system that provide a microenvironmental niche in regulating the ESC-like cells within the KALTs. These ESC-like cells may be a novel therapeutic target for the treatment of this enigmatic and challenging condition, by modulating the RAS using inhibitors of the RAS and its bypass loops and convergent signaling pathways.

To analyse, by means of a meta-analytical approach, the diagnostic accuracy of molecular biomarkers in gingival crevicular fluid (GCF) for the detection of periodontitis in systemically healthy subjects.
Studies on GCF molecular biomarkers providing a binary classification table (or sensitivity and specificity values and group sample sizes) in individuals with clinically diagnosed periodontitis were considered eligible. The search was performed using six electronic databases. The methodological quality of studies was assessed through the tool Quality Assessment of Diagnostic Studies. Meta-analyses were performed using the Hierarchical Summary Receiver Operating Characteristic, which adjusts classification data using random effects logistic regression.
The included papers identified 36 potential biomarkers for the detection of periodontitis and for four of them meta-analyses were performed. The median sensitivity and specificity were for MMP8, 76.7% and 92.0%; for elastase, 74.6% and 81.1%; for cathepsin, 72.8% and 67.3%, respectively. The worst estimates of sensitivity and specificity were for trypsin (71.3% and 66.1%, respectively).
MMP8 showed good sensitivity and excellent specificity, which resulted in this biomarker being clinically the most useful or effective for the diagnosis of periodontitis in systemically healthy subjects, regardless of smoking condition.

Low-grade inflammation (LGI) has been suggested to be involved in the development of chronic diseases. Healthy dietary patterns, such as the Mediterranean diet (MD), may decrease the markers of LGI. Healthy Nordic diet (HND) has many similarities with MD, but its effects on LGI are less well known. Both of these dietary patterns emphasize the abundant use of fruits and vegetables (and berries in HND), whole grain products, fish, and vegetable oil (canola oil in HND and olive oil in MD), but restrict the use of saturated fat and red and processed meat. The aim of this narrative review is to summarize the results of studies, which have investigated the associations or effects of HND on the markers of LGI. Altogether, only two publications of observational studies and eight publications of intervention trials were found through the literature search. Both observational studies reported an inverse association between the adherence to HND and concentration of high sensitivity C-reactive protein (hsCRP). A significant decrease in the concentration of hsCRP was reported in two out of four intervention studies measuring hsCRP. Single intervention studies reported the beneficial effects on interleukin 1Ra and Cathepsin S. Current evidence suggests the beneficial effects on LGI with HND, but more carefully controlled studies are needed to confirm the anti-inflammatory effects of the HND.

Excessive activities of cysteinyl cathepsins (CysCts) contribute to the progress of many diseases; however, therapeutic inhibition has been problematic. Zn2+ is a natural inhibitor of proteases with CysHis dyads or CysHis(Xaa) triads. Biguanide forms bidentate metal complexes through the two imino nitrogens. Here, it is discussed that phenformin (phenylethyl biguanide) is a model for recruitment of endogenous Zn2+ to inhibit CysHis/CysHis(X) peptidolysis. Phenformin is a Zn2+-interactive, anti-proteolytic agent in bioassay of living tissue. Benzoyl-L-arginine amide (BAA) is a classical substrate of papain-like proteases; the amide bond is scissile. In this review, the structures of BAA and the phenformin-Zn2+ complex were compared in silico. Their chemistry and dimensions are discussed in light of the active sites of papain-like proteases. The phenyl moieties of both structures bind to the \"S2\" substrate-binding site that is typical of many proteases. When the phenyl moiety of BAA binds to S2, then the scissile amide bond is directed to the position of the thiolate-imidazolium ion pair, and is then hydrolyzed. However, when the phenyl moiety of phenformin binds to S2, then the coordinated Zn2+ is directed to the identical position; and catalysis is inhibited. Phenformin stabilizes a \"Zn2+ sandwich\" between the drug and protease active site. Hundreds of biguanide derivatives have been synthesized at the 1 and 5 nitrogen positions; many more are conceivable. Various substituent moieties can register with various arrays of substrate-binding sites so as to align coordinated Zn2+ with catalytic partners of diverse proteases. Biguanide is identified here as a modifiable pharmacophore for synthesis of therapeutic CysCt inhibitors with a wide range of potencies and specificities. Phenformin-Zn2+ Complex.

BACKGROUND: Periodontitis is a prevalent oral disease with bone loss being it\'s hallmark. Clinical parameters used to measure periodontitis are retrospective and do not indicate active inflammation nor prognosis. GCF can be easily collected chairside and bone turnover biomarkers found in GCF can be evaluated to check for active inflammation and disease progression. This systematic review aims to evaluate the literature for association and predictive value of bone turnover biomarkers in GCF during periodontal disease.
METHODS: This review was conducted and reported according to the PRISMA guidelines. The online databases Google Scholar and PubMed were used for data search. MeSH terms were used for PubMed search. All original studies from 1990 to 2017 conducted on human subjects in the English language were included in the review. Studies on non-human subjects, reviews and studies conducted in languages other than English were not considered. Reference lists of qualified articles were also searched.
RESULTS: The search generated 2300 results whose titles were screened and 1571 articles were retreived. 23 articles were accepted in the review and full texts were accessed. These included 1 randomized controlled trial, 12 cross-sectional studies, five pre-post interventional studies, 4 longitudinal and 1 in-vitro in-vivo experimental study. The studies were conducted on patients of both genders ranging from 10 to 81 years in age. A total of 37 biomarkers were evalueted in the studies included in this review. Majority of the studies reported interleukin-1β (IL-1β) while receptor activated nuclear factor-kappa B ligand (RANKL) and matrix metalloproteinase-8 (MMP-8) were the other frequently reported biomarkers. Most of the studies evaluated more than two biomarkers. ELISA was the most commonly used biochemical test used for detection.
CONCLUSIONS: A wide range of biomarkers have been established as indicators of alveolar bone resorption. Few of the biomarkers have also shown positive correlation with disease progression and outcome of periodontal therapies thus underscoring their predictive value in periodontal diagnosis and prognosis. Not one single biomarker has been reported to have a predictive advantage over another and a combination of two or more biomarkers along with clinical evaluation is recommended.

Molecularly targeted therapeutic and imaging strategies directed at aberrant signaling pathways in pancreatic tumor cells may improve the poor outcome of pancreatic ductal adenocarcinoma (PDA). Therefore, relevant molecular targets need to be identified. Methods: We collected publicly available expression profiles of patient-derived normal pancreatic tissue (n = 77) and PDA samples (n = 103). Functional genomic messenger RNA profiling was applied to predict target upregulation on the protein level. We prioritized these targets based on current status of preclinical therapeutic and imaging evaluation in PDA. Results: We identified 213 significantly upregulated proteins in PDA compared with normal pancreatic tissue. We prioritized mucin-1, mesothelin, γ-glutamyltransferase 5, and cathepsin-E as the most interesting targets, because studies already demonstrated their potential for both therapeutic and imaging strategies in literature. Conclusion: This study can assist clinicians and drug developers in deciding which theranostic targets should be taken for further clinical evaluation in PDA.

Cysteine proteases play multiple roles in basically all aspects of physiology and development. In plants, they are involved in growth and development and in accumulation and mobilization of storage proteins. Furthermore, they are engaged in signalling pathways and in the response to biotic and abiotic stresses. In animals and also in humans, they are responsible for senescence and apoptosis, prohormone processing, and ECM remodelling. When analyzed by zymography, the enzyme must be renaturated after SDS-PAGE. SDS must be washed out and substituted by Triton X-100. Gels are then further incubated under ideal conditions for activity detection. Cysteine proteases require an acidic pH (5.0-6.0) and a reducing agent, usually DTT. When screening biological samples, there is generally no previous clue on what peptidase class will be present, neither optimal proteolysis conditions are known. Hence, it is necessary to assess several parameters, such as incubation time, pH, temperature, influence of ions or reducing agents, and finally evaluate the inhibition profile. For detection of cysteine peptidase activity, the use of specific inhibitors, such as E-64, can be used to prevent the development of cysteine peptidase activity bands and positively confirm its presence. Here four different protocols to assess cysteine protease activity from different sources are presented.