Structure-based design and in vivo anti-arthritic activity evaluation of a potent dipeptidyl cyclopropyl nitrile inhibitor of cathepsin C

Cathepsin C exacerbates EAE by promoting the expansion of Tfh cells and the formation of TLSs in the CNS

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) mediated by CD4+ T helper (Th) cells, and characterized by immune cell infiltration, demyelination and neurodegeneration, with no definitive cure available. Thus, it is pivotal and imperative to acquire more profound comprehension of the underlying mechanisms implicated in MS. Dysregulated immune responses are widely believed to play a primary role in the pathogenesis of MS. Recently, a plethora of studies have demonstrated the involvement of T follicular helper (Tfh) cells and tertiary lymphoid-like structures (TLSs) in the pathogenesis and progression of MS. Cathepsin C (CatC) is a cysteine exopeptidase which is crucial for the activation of immune-cell-associated serine proteinases in many inflammatory diseases in peripheral system, such as rheumatoid arthritis and septicemia. We have previously demonstrated that CatC is involved in neuroinflammation and exacerbates demyelination in both cuprizone-induced and experimental autoimmune encephalomyelitis (EAE) mouse models. However, the underlying immunopathological mechanism remains elusive. In the present study, we established a recombinant myelin oligodendrocyte glycoprotein 35-55 peptide-induced EAE model using conditional CatC overexpression mice to investigate the effects of CatC on the alteration of CD4+ Th subsets, including Th1, Th2, Th17, Tfh and T regulatory cells. Our findings demonstrated that CatC particularly enhanced the population of Tfh cell in the brain, resulting in the earlier onset and more severe chronic syndrome of EAE. Furthermore, CatC promoted the formation of TLSs in the brain, leading to persistent neuroinflammation and exacerbating the severity of EAE in the chronic phase. Conversely, treatment with AZD7986, a specific inhibitor of CatC, effectively attenuated the syndrome of EAE and its effects caused by CatC both in vivo and in vitro. These findings provide a novel insight into the critical role of CatC in innate and adaptive immunity in EAE, and specific inhibitor of CatC, AZD7986, may contribute to potential therapeutic strategies for MS.

Programmed Cell Death-Related Gene Signature Associated with Prognosis and Immune Infiltration and the Roles of HMOX1 in the Proliferation and Apoptosis were Investigated in Uveal Melanoma

BACKGROUND

Uveal melanoma (UVM) is the most common primary ocular malignancy, with a wide range of symptoms and outcomes. The programmed cell death (PCD) plays an important role in tumor development, diagnosis, and prognosis. There is still no research on the relationship between PCD-related genes and UVM. A novel PCD-associated prognostic model is urgently needed to improve treatment strategies.

OBJECTIVE

We aim to screen PCD-related prognostic signature and investigate its proliferation ability and apoptosis in UVM cells.

METHODS

The clinical information and RNA-seq data of the UVM patients were collected from the TCGA cohort. All the patients were classified using consensus clustering by the selected PCD-related genes. After univariate Cox regression and PPI network analysis, the prognostic PCD-related genes were then submitted to the LASSO regression analysis to build a prognostic model. The level of immune infiltration of 8-PCD signature in high- and low-risk patients was analyzed using xCell. The prediction on chemotherapy and immunotherapy response in UVM patients was assessed by GDSC and TIDE algorithm. CCK-8, western blot and Annexin V-FITC/PI staining were used to explore the roles of HMOX1 in UVM cells.

RESULTS

A total of 8-PCD signature was constructed and the risk score of the PCD signature was negatively correlated with the overall survival, indicating strong predictive ability and independent prognostic value. The risk score was positively correlated with CD8 Tcm, CD8 Tem and Th2 cells. Immune cells in high-risk group had poorer overall survival. The drug sensitivity demonstrated that cisplatin might impact the progression of UVM and better immunotherapy responsiveness in the high-risk group. Finally, Overespression HMOX1 (OE-HMOX1) decreased the cell viability and induced apoptosis in UVM cells. Recuse experiment results showed that ferrostatin-1 (fer-1) protected MP65 cells from apoptosis and necrosis caused by OE-HMOX1.

CONCLUSION

The PCD signature may have a significant role in the tumor microenvironment, clinicopathological characteristics, prognosis and drug sensitivity. More importantly, HMOX1 depletion greatly induced tumor cell growth and inhibited cell apoptosis and fer-1 protected UVM cells from apoptosis and necrosis induced by OE-HMOX1. This work provides a foundation for effective therapeutic strategy in tumour treatment.

Neutrophil-Derived Proteases in Lung Inflammation: Old Players and New Prospects

Neutrophil-derived proteases are critical to the pathology of many inflammatory lung diseases, both chronic and acute. These abundant enzymes play roles in key neutrophil functions, such as neutrophil extracellular trap formation and reactive oxygen species release. They may also be released, inducing tissue damage and loss of tissue function. Historically, the neutrophil serine proteases (NSPs) have been the main subject of neutrophil protease research. Despite highly promising cell-based and animal model work, clinical trials involving the inhibition of NSPs have shown mixed results in lung disease patients. As such, the cutting edge of neutrophil-derived protease research has shifted to proteases that have had little-to-no research in neutrophils to date. These include the cysteine and serine cathepsins, the metzincins and the calpains, among others. This review aims to outline the previous work carried out on NSPs, including the shortcomings of some of the inhibitor-orientated clinical trials. Our growing understanding of other proteases involved in neutrophil function and neutrophilic lung inflammation will then be discussed. Additionally, the potential of targeting these more obscure neutrophil proteases will be highlighted, as they may represent new targets for inhibitor-based treatments of neutrophil-mediated lung inflammation.

Brensocatib (an oral, reversible inhibitor of dipeptidyl peptidase-1) attenuates disease progression in two animal models of rheumatoid arthritis

Rheumatoid arthritis (RA) is a painful and incurable disease characterized by chronic joint inflammation and a progressive destruction of cartilage and bone. Although current treatments have improved clinical outcomes for some patients, the high relapse rates and sizeable proportion of non-responders emphasize the need for further research. Arthritic joints are massively infiltrated by neutrophils, which influence inflammatory and immune processes by releasing cytokines, chemokines, eicosanoids, and neutrophil serine proteases (NSPs) - all of which are known to contribute to RA initiation and progression. Active NSPs are generated from zymogens at the promyelocytic stage of neutrophil differentiation under the action of dipeptidyl peptidase 1 (DPP-1) and DPP-1 knockout mice are resistant to the development of arthritis. Thus, DPP-1 inhibition represents a promising therapeutic approach in RA. In this study, we assessed the efficacy of a potent and highly selective DPP-1 inhibitor, brensocatib, in two well established RA models - rat collagen-induced arthritis (CIA) and mouse collagen antibody-induced arthritis (CAIA). In both models, brensocatib at 3 and 30 mg/kg/day significantly reduced bone marrow NSP levels, in keeping with prior pharmacodynamic studies in rodents. More importantly, brensocatib treatment significantly improved disease score at both dosages in both rodent models. In the mouse CAIA model, brensocatib even proved at least as potent as anti-TNF antibodies in diminishing both the histopathological score and neutrophil infiltration into arthritic joints. Together, these results show that brensocatib alters RA disease progression in rodents and supports the need for its further evaluation as a potential therapeutic option, or to complement existing RA treatments.

Neutrophils play a major role in the destruction of the olfactory epithelium during SARS-CoV-2 infection in hamsters

The loss of smell (anosmia) related to SARS-CoV-2 infection is one of the most common symptoms of COVID-19. Olfaction starts in the olfactory epithelium mainly composed of olfactory sensory neurons surrounded by supporting cells called sustentacular cells. It is now clear that the loss of smell is related to the massive infection by SARS-CoV-2 of the sustentacular cells in the olfactory epithelium leading to its desquamation. However, the molecular mechanism behind the destabilization of the olfactory epithelium is less clear. Using golden Syrian hamsters infected with an early circulating SARS-CoV-2 strain harboring the D614G mutation in the spike protein; we show here that rather than being related to a first wave of apoptosis as proposed in previous studies, the innate immune cells play a major role in the destruction of the olfactory epithelium. We observed that while apoptosis remains at a low level in the damaged area of the infected epithelium, the latter is invaded by Iba1+ cells, neutrophils and macrophages. By depleting the neutrophil population or blocking the activity of neutrophil elastase-like proteinases, we could reduce the damage induced by the SARS-CoV-2 infection. Surprisingly, the impairment of neutrophil activity led to a decrease in SARS-CoV-2 infection levels in the olfactory epithelium. Our results indicate a counterproductive role of neutrophils leading to the release of infected cells in the lumen of the nasal cavity and thereby enhanced spreading of the virus in the early phase of the SARS-CoV-2 infection.

An optimized method of extracting and quantifying active Neutrophil serine proteases from human whole blood cells

Purpose

Neutrophil serine proteases (NSPs) are implicated in numerous inflammatory diseases. Thus, a robust methodology to monitor and quantify NSPs is important to study disease progression and evaluate the effect of pharmacological interventions. A comparison of the various methods used to extract NSPs from neutrophil granulocytes has not been published, providing the impetus to conduct this method optimization and comparison study.

Methods

Two NSP recovery methodologies were evaluated on samples from five human donors: zymosan stimulation and cell pellet extraction. For the zymosan stimulation method, 1 mL donor blood was added to zymosan and samples were incubated at 37°C for 30 min while shaking. Samples were then centrifuged, and the plasma was collected for quantitation of NSP activity. For the cell pellet extraction procedure, 2 mL whole blood samples were centrifuged into white blood cell pellets following red blood cell lysis. To each pellet, three sequential lysis steps were performed using either 0.05% Nonidet P-40 Substitute (NP40) or 0.02% Triton X-100 lysis buffers under agitation followed by centrifugation. NSP activities were quantified using an exogenous peptide substrate specific to each of the three NSPs being analyzed: neutrophil elastase, cathepsin G, and proteinase 3.

Results and discussion

The zymosan stimulation method resulted in lower recovery of active NSPs and was unable to stimulate significant release of active cathepsin G. In contrast, the NP40 pellet extraction method showed consistent inter-donor NSP release with greater recoveries of active NSPs than the Triton method or the zymosan stimulation method. Overall, the pellet extraction procedure provided 13.3-fold greater recovery of active neutrophil elastase, 283-fold greater recovery of active cathepsin G, and 2.9-fold greater recovery of active proteinase 3 than the zymosan method.

Conclusion

The NP40 cell pellet extraction method resulted in greater extraction of active NSPs compared to the other methods investigated here, which may allow for a more accurate and complete biomarker profile when evaluating human clinical samples.

The history, mechanism, and perspectives of nirmatrelvir (PF-07321332): an orally bioavailable main protease inhibitor used in combination with ritonavir to reduce COVID-19-related hospitalizations

The rapid development of effective vaccines to combat the SARS-CoV-2 virus has been an effective counter measure to decrease hospitalization and the mortality rate in many countries. However, with the risk of mutated strains decreasing the efficacy of the vaccine, there has been an increasing demand for antivirals to treat COVID-19. While antivirals, such as remdesivir, have had some success treating COVID-19 patients in hospital settings, there is a need for orally bioavailable, cost-effective antivirals that can be administered in outpatient settings to minimize COVID-19-related hospitalizations and death. Nirmatrelvir (PF-07321332) is an orally bioavailable M^pro (also called 3CL^pro) inhibitor developed by Pfizer. It is administered in combination with ritonavir, a potent CYP3A4 inhibitor that decreases the metabolism of nirmatrelvir. This review seeks to outline the history of the rational design, the target selectivity, synthesis, drug resistance, and future perspectives of nirmatrelvir.

Synthesis of Hybrid Tripeptide Peptidomimetics Containing Dehydroamino Acid and Aminophosphonic Acid in the Chain and Evaluation of Their Activity toward Cathepsin C

Synthesis of a new group of hybrid phosphonodehydropeptides composed of glycyl-(Z)-dehydrophenylalanine and structurally variable aminophosphonates alongside with investigations of their activity towards cathepsin C are presented. Obtained results suggest that the introduction of (Z)-dehydrophenylalanine residue into the short phosphonopeptide chain does induce the ordered conformation. Investigated peptides appeared to act as weak or moderate inhibitors of cathepsin C.

Targeting Cathepsin C in PR3-ANCA Vasculitis

BACKGROUND

The ANCA autoantigens proteinase 3 (PR3) and myeloperoxidase (MPO) are exclusively expressed by neutrophils and monocytes. ANCA-mediated activation of these cells is the key driver of the vascular injury process in ANCA-associated vasculitis (AAV), and neutrophil serine proteases (NSPs) are disease mediators. Cathepsin C (CatC) from zymogens activates the proteolytic function of NSPs, including PR3. Lack of NSP zymogen activation results in neutrophils with strongly reduced NSP proteins.

METHODS

To explore AAV-relevant consequences of blocking NSP zymogen activation by CatC, we used myeloid cells from patients with Papillon-Lefèvre syndrome, a genetic deficiency of CatC, to assess NSPs and NSP-mediated endothelial cell injury. We also examined pharmacologic CatC inhibition in neutrophil-differentiated human hematopoietic stem cells, primary human umbilical vein cells, and primary glomerular microvascular endothelial cells.

RESULTS

Patients with Papillon-Lefèvre syndrome showed strongly reduced NSPs in neutrophils and monocytes. Neutrophils from these patients produced a negative PR3-ANCA test, presented less PR3 on the surface of viable and apoptotic cells, and caused significantly less damage in human umbilical vein cells. These findings were recapitulated in human stem cells, in which a highly specific CatC inhibitor, but not prednisolone, reduced NSPs without affecting neutrophil differentiation, reduced membrane PR3, and diminished neutrophil activation upon PR3-ANCA but not MPO-ANCA stimulation. Compared with healthy controls, neutrophils from patients with Papillon-Lefèvre syndrome transferred less proteolytically active NSPs to glomerular microvascular endothelial cells, the cell type targeted in ANCA-induced necrotizing crescentic glomerulonephritis. Finally, both genetic CatC deficiency and pharmacologic inhibition, but not prednisolone, reduced neutrophil-induced glomerular microvascular endothelial cell damage.

CONCLUSIONS

These findings may offer encouragement for clinical studies of adjunctive CatC inhibitor in patients with PR3-AAV.

Downregulation of cathepsin C alleviates endothelial cell dysfunction by suppressing p38 MAPK/NF-κB pathway in preeclampsia

Endothelial cell dysfunction is an essential pathophysiological feature of preeclampsia (PE). It has been reported that cathepsin C is upregulated in the maternal vascular endothelium of PE patients. The excessive activation of p38 MAPK leads to various diseases, including PE. NF-κB pathway can promote uteroplacental dysfunction, endothelial stress and development of PE. Moreover, it has been verified that cathepsin C can activate p38 MAPK/NF-κB pathway. In the present work, hypoxia/reoxygenation (H/R) injury model of HUVECs was established to discuss the biological functions of cathepsin C in endothelial cell dysfunction and to elucidate the underlying molecular mechanism. The correlation between cathepsin C and p38 MAPK/NF-κB pathway in H/R-stimulated HUVECs as well as the effects of cathepsin C and p38 MAPK/NF-κB pathway on viability, apoptosis, invasion, in vitro angiogenesis of HUVECs and oxidative stress were assessed. The results revealed that H/R injury elevated cathepsin C expression and activated p38 MAPK/NF-κB pathway in HUVECs and cathepsin C knockdown inhibited the activity of p38 MAPK/NF-κB pathway in H/R-stimulated HUVECs. Downregulation of cathepsin C improved viability, inhibited apoptosis and enhanced invasion of H/R-stimulated HUVECs. In addition, downregulation of cathepsin C alleviated oxidative stress and induced stronger HUVEC angiogenesis in vitro. Furthermore, the protective effects of cathepsin C knockdown against endothelial cell dysfunction were reversed by p38 MAPK activator anisomycin. In other words, downregulation of cathepsin C could improve HUVEC viability and enhance anti-apoptotic capacity, anti-oxidative capability, invasive ability, as well as angiogenic potential of H/R-stimulated HUVECs by repressing p38 MAPK/NF-κB pathway.

Cathepsin C inhibitors as anti-inflammatory drug discovery: Challenges and opportunities

Cathepsin C, an important lysosomal cysteine protease, mediates the maturation process of neutrophil serine proteases, and participates in the inflammation and immune regulation process associated with polymorphonuclear neutrophils. Therefore, cathepsin C is considered to be an attractive target for treating inflammatory diseases. With INS1007 (trade name: brensocatib) being granted a breakthrough drug designation by FDA for the treatment of Adult Non-cystic Fibrosis Bronchiectasis and Coronavirus Disease 2019, the development of cathepsin C inhibitor will attract attentions from medicinal chemists in the future soon. Here, we summarized the research results of cathepsin C as a therapeutic target, focusing on the development of cathepsin C inhibitor, and provided guidance and reference opinions for the upcoming development boom of cathepsin C inhibitor.

Hindrance of the Proteolytic Activity of Neutrophil-Derived Serine Proteases by Serine Protease Inhibitors as a Management of Cardiovascular Diseases and Chronic Inflammation

During inflammation neutrophils become activated and segregate neutrophil serine proteases (NSPs) to the surrounding environment in order to support a natural immune defense. However, an excess of proteolytic activity of NSPs can cause many complications, such as cardiovascular diseases and chronic inflammatory disorders, which will be elucidated on a biochemical and immunological level. The application of selective serine protease inhibitors is the logical consequence in the management of the indicated comorbidities and will be summarized in this briefing.

Cathepsin C inhibition as a potential treatment strategy in cancer

Epidemiological studies established an association between chronic inflammation and higher risk of cancer. Inhibition of proteolytic enzymes represents a potential treatment strategy for cancer and prevention of cancer metastasis. Cathepsin C (CatC) is a highly conserved lysosomal cysteine dipeptidyl aminopeptidase required for the activation of pro-inflammatory neutrophil serine proteases (NSPs, elastase, proteinase 3, cathepsin G and NSP-4). NSPs are locally released by activated neutrophils in response to pathogens and non-infectious danger signals. Activated neutrophils also release neutrophil extracellular traps (NETs) that are decorated with several neutrophil proteins, including NSPs. NSPs are not only NETs constituents but also play a role in NET formation and release. Although immune cells harbor large amounts of CatC, additional cell sources for this protease exists. Upregulation of CatC expression was observed in different tissues during carcinogenesis and correlated with metastasis and poor patient survival. Recent mechanistic studies indicated an important interaction of tumor-associated CatC, NSPs, and NETs in cancer development and metastasis and suggested CatC as a therapeutic target in a several cancer types. Cancer cell-derived CatC promotes neutrophil recruitment in the inflammatory tumor microenvironment. Because the clinical consequences of genetic CatC deficiency in humans resulting in the elimination of NSPs are mild, small molecule inhibitors of CatC are assumed as safe drugs to reduce the NSP burden. Brensocatib, a nitrile CatC inhibitor is currently tested in a phase 3 clinical trial as a novel anti-inflammatory therapy for patients with bronchiectasis. However, recently developed CatC inhibitors possibly have protective effects beyond inflammation. In this review, we describe the pathophysiological function of CatC and discuss molecular mechanisms substantiating pharmacological CatC inhibition as a potential strategy for cancer treatment.

Discovery and In Vivo Anti-inflammatory Activity Evaluation of a Novel Non-peptidyl Non-covalent Cathepsin C Inhibitor

Cathepsin C (Cat C) participates in inflammation and immune regulation by affecting the activation of neutrophil serine proteases (NSPs). Therefore, cathepsin C is an attractive target for treatment of NSP-related inflammatory diseases. Here, the complete discovery process of the first potent "non-peptidyl non-covalent cathepsin C inhibitor" was described with hit finding, structure optimization, and lead discovery. Starting with hit 14, structure-based optimization and structure-activity relationship study were comprehensively carried out, and lead compound 54 was discovered as a potent drug-like cathepsin C inhibitor both in vivo and in vitro. Also, compound 54 (with cathepsin C Enz IC50 = 57.4 nM) exhibited effective anti-inflammatory activity in an animal model of chronic obstructive pulmonary disease. These results confirmed that the non-peptidyl and non-covalent derivative could be used as an effective cathepsin C inhibitor and encouraged us to continue further drug discovery on the basis of this finding.

Lung Protection by Cathepsin C Inhibition: A New Hope for COVID-19 and ARDS?

Cathepsin C (CatC) is a cysteine dipeptidyl aminopeptidase that activates most of tissue-degrading elastase-related serine proteases. Thus, CatC appears as a potential therapeutic target to impair protease-driven tissue degradation in chronic inflammatory and autoimmune diseases. A depletion of proinflammatory elastase-related proteases in neutrophils is observed in patients with CatC deficiency (Papillon-Lefèvre syndrome). To address and counterbalance unwanted effects of elastase-related proteases, chemical inhibitors of CatC are being evaluated in preclinical and clinical trials. Neutrophils may contribute to the diffuse alveolar inflammation seen in acute respiratory distress syndrome (ARDS) which is currently a growing challenge for intensive care units due to the outbreak of the COVID-19 pandemic. Elimination of elastase-related neutrophil proteases may reduce the progression of lung injury in these patients. Pharmacological CatC inhibition could be a potential therapeutic strategy to prevent the irreversible pulmonary failure threatening the life of COVID-19 patients.

Cathepsins in the Pathophysiology of Mucopolysaccharidoses: New Perspectives for Therapy

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

Therapeutic targeting of neutrophil exocytosis

Dysregulation of neutrophil activation causes disease in humans. Neither global inhibition of neutrophil functions nor neutrophil depletion provides safe and/or effective therapeutic approaches. The role of neutrophil granule exocytosis in multiple steps leading to recruitment and cell injury led each of our laboratories to develop molecular inhibitors that interfere with specific molecular regulators of secretion. This review summarizes neutrophil granule formation and contents, the role granule cargo plays in neutrophil functional responses and neutrophil-mediated diseases, and the mechanisms of granule release that provide the rationale for development of our exocytosis inhibitors. We present evidence for the inhibition of granule exocytosis in vitro and in vivo by those inhibitors and summarize animal data indicating that inhibition of neutrophil exocytosis is a viable therapeutic strategy.

DPP1 Inhibitors: Exploring the Role of Water in the S2 Pocket of DPP1 with Substituted Pyrrolidines

A series of pyrrolidine amino nitrile DPP1 inhibitors have been developed and characterized. The S2 pocket structure-activity relationship for these compounds shows significant gains in potency for DPP1 from interacting further with target residues and a network of water molecules in the binding pocket. Herein we describe the X-ray crystal structures of several of these compounds alongside an analysis of factors influencing the inhibitory potency toward DPP1 of which stabilization of the water network, demonstrated using Grand Canonical Monte Carlo simulations and free energy calculations, is attributed as a main factor.