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Background Brensocatib is an oral, selective, reversible inhibitor of dipeptidyl peptidase-1 (DPP-1), responsible for activating neutrophil serine proteases (NSPs) including neutrophil elastase (NE), proteinase 3 (PR3), and cathepsin G (CatG). In chronic inflammatory lung diseases such as non-cystic fibrosis bronchiectasis (NCFBE), neutrophils accumulate in the airways resulting in excess active NSPs that cause damaging inflammation and lung destruction. Methods The 24-week WILLOW trial (NCT03218917) was a randomized, double-blind, placebo-controlled, parallel-group trial in patients with NCFBE conducted at 116 sites across 14 countries. In this trial, treatment with brensocatib was associated with improvements in clinical outcomes including time to first exacerbation, reduction in exacerbation frequency and a reduction in NE activity in sputum. An exploratory analysis of NE activity in white blood cell (WBC) extracts and NE, PR3 and CatG activity in sputum was conducted to further characterize brensocatib’s effect and identify potential correlated effects. Results NE, PR3 and CatG activities were reduced in sputum and NE activity was reduced in WBC extracts in a dose-dependent manner after four weeks of brensocatib treatment, with a return to baseline four weeks after the end of treatment. Brensocatib produced the greatest reduction in the sputum activity of CatG, followed by NE and then PR3. Positive correlations among the sputum NSPs were observed both at baseline and in response to treatment, with the strongest correlation among the sputum NSPs for NE and CatG. Conclusions These results suggest a broad anti-inflammatory effect of brensocatib underlying its clinical efficacy observed in NCFBE patients. Trial registration: The study was approved by the corresponding ethical review boards of all participating centers. The trial was approved by the Food and Drug Administration and registered at clinicaltrials.gov (NCT03218917) on July 17, 2017 and approved by the European Medicines Agency and registered at the European Union Clinical trials Register (EudraCT No. 2017-002533-32). An independent, external data and safety monitoring committee (comprising physicians with pulmonary expertise, a statistician experienced in the evaluation of clinical safety, and experts in periodontal disease and dermatology) reviewed all adverse events.

The causal role of neutrophil serine proteases in the pathogenesis of bronchiectasis was studied with brensocatib, an inhibitor of protease activation. Brensocatib therapy resulted in a longer time to the first bronchiectasis exacerbation than placebo.

Commensal bacteria are known to inhibit pathogen colonization; however, complex host–microbe and microbe–microbe interactions have made it difficult to gain a detailed understanding of the mechanisms involved in the inhibition of colonization 1 . Here we show that the serine protease Esp 2 , 3 secreted by a subset of Staphylococcus epidermidis , a commensal bacterium, inhibits biofilm formation and nasal colonization by Staphylococcus aureus , a human pathogen 4 . Epidemiological studies have demonstrated that the presence of Esp-secreting S. epidermidis in the nasal cavities of human volunteers correlates with the absence of S. aureus . Purified Esp inhibits biofilm formation and destroys pre-existing S. aureus biofilms. Furthermore, Esp enhances the susceptibility of S. aureus in biofilms to immune system components. In vivo studies have shown that Esp-secreting S. epidermidis eliminates S. aureus nasal colonization. These findings indicate that Esp hinders S. aureus colonization in vivo through a novel mechanism of bacterial interference, which could lead to the development of novel therapeutics to prevent S. aureus colonization and infection.

Proteolytic activation of phenoloxidase (PO) and the cytokine Spätzle during immune responses of insects is mediated by a network of hemolymph serine proteases (HPs) and noncatalytic serine protease homologs (SPHs) and inhibited by serpins. However, integration and conservation of the system and its control mechanisms are not fully understood. Here we present biochemical evidence that PO-catalyzed melanin formation, Spätzle-triggered Toll activation, and induced synthesis of antimicrobial peptides are stimulated via hemolymph (serine) protease 5 (HP5) in Manduca sexta. Previous studies have demonstrated a protease cascade pathway in which HP14 activates proHP21; HP21 activates proPAP2 and proPAP3, which then activate proPO in the presence of a complex of SPH1 and SPH2. We found that both HP21 and PAP3 activate proHP5 by cleavage at ESDR176*IIGG. HP5 then cleaves proHP6 at a unique site of LDLH112*ILGG. HP6, an ortholog of Drosophila Persephone, activates both proHP8 and proPAP1. HP8 activates proSpätzle-1, whereas PAP1 cleaves and activates proPO. HP5 is inhibited by Manduca sexta serpin-4, serpin-1A, and serpin-1J to regulate its activity. In summary, we have elucidated the physiological roles of HP5, a CLIPB with unique cleavage specificity (cutting after His) that coordinates immune responses in the caterpillar.

Serine proteases exist in eukaryotic and prokaryotic organisms and have emerged during evolution as the most abundant and functionally diverse group. In Gram-negative bacteria, there is a growing family of high molecular weight serine proteases secreted to the external milieu by a fascinating and widely employed bacterial secretion mechanism, known as the autotransporter pathway. They were initially found in Neisseria, Shigella, and pathogenic Escherichia coli, but have now also been identified in Citrobacter rodentium, Salmonella, and Edwardsiella species. Here, we focus on proteins belonging to the serine protease autotransporter of Enterobacteriaceae (SPATEs) family. Recent findings regarding the predilection of serine proteases to host intracellular or extracellular protein-substrates involved in numerous biological functions, such as those implicated in cytoskeleton stability, autophagy or innate and adaptive immunity, have helped provide a better understanding of SPATEs’ contributions in pathogenesis. Here, we discuss their classification, substrate specificity, and potential roles in pathogenesis.

This study describes the characterization and optimization of medium components for an extracellular detergent, surfactant, organic solvent and thermostable serine alkaline protease produced by alkaliphilic Bacillus pumilus MCAS8 strain isolated from Pulicat lake sediments, Tamil Nadu, India. The strain yielded maximum protease (2,214 U/ml) under optimized conditions: carbon source, citric acid—1.5 % ( w / w ); inducer, soyabean meal—2 % ( w / w ); pH 11.0; shaking condition 37 °C for 48 h. The enzyme had pH and temperature optima of 9.0 and 60 °C, respectively. The enzyme displayed the molecular mass of 36 kDa in sodium dodecyl sulphate–polyacrylamide gel electrophoresis study and exhibited activity at a wide range of pH (6.0–11.0) and thermostability (20–70 °C). More than 70 % residual activity was observed when the enzyme was incubated with dithiothreitol, ethylenediaminetetraacetic acid, ethylene glycol tetraacetic acid and H 2 O 2 for 30 min. The protease activity was also enhanced by divalent cations such as Ba 2+ , Ca 2+ and Mg 2+ and was strongly inhibited by Fe 2+ , Zn 2+ , Sr 2+ , Hg 2+ and urea. The enzyme retained more than 50 % of its initial activity after pre-incubation for 1 h in the presence of 5 % ( v / v ) organic solvents such as dimethyl sulphoxide and acetone. The protease could hydrolyse various native proteinaceous substrates (1 %  w / v ) such as bovine serum albumin, casein, skim milk, gelatine, azocasein and haemoglobin. Wash performance analysis of enzyme revealed that it could effectively remove blood stains from the cotton fabric, thus making it suitable to use as an effective detergent additive. The protease enzyme also exhibited promising result in the dehairing of goat skin. The potency of the eco-friendly enzyme without using any chemicals against washing and dehairing showed that the enzyme could be used for various industrial applications.

Plant-parasitic nematodes (PPNs) cause serious harm to agricultural production. Bacillus firmus shows excellent control of PPNs and has been produced as a commercial nematicide. However, its nematicidal factors and mechanisms are still unknown. In this study, we showed that B. firmus strain DS-1 has high toxicity against Meloidogyne incognita and soybean cyst nematode. We sequenced the whole genome of DS-1 and identified multiple potential virulence factors. We then focused on a peptidase S8 superfamily protein called Sep1 and demonstrated that it had toxicity against the nematodes Caenorhabditis elegans and M. incognita . The Sep1 protein exhibited serine protease activity and degraded the intestinal tissues of nematodes. Thus, the Sep1 protease of B. firmus is a novel biocontrol factor with activity against a root-knot nematode. We then used C. elegans as a model to elucidate the nematicidal mechanism of Sep1 and the results showed that Sep1 could degrade multiple intestinal and cuticle-associated proteins and destroyed host physical barriers. The knowledge gained in our study will lead to a better understanding of the mechanisms of B. firmus against PPNs and will aid in the development of novel bio-agents with increased efficacy for controlling PPNs.

Keratinases are exciting proteolytic enzymes that display the capability to degrade the insoluble protein keratin. These enzymes are produced by diverse microorganisms belonging to the Eucarya, Bacteria, and Archea domains. Keratinases display a great diversity in their biochemical and biophysical properties. Most keratinases are optimally active at neutral to alkaline pH and 40-60°C, but examples of microbial keratinolysis at alkalophilic and thermophilic conditions have been well documented. Several keratinases have been associated to the subtilisin family of serine-type proteases by analysis of their protein sequences. Studies with specific substrates and inhibitors indicated that keratinases are often serine or metalloproteases with preference for hydrophobic and aromatic residues at the P1 position. Keratinolytic enzymes have several current and potential applications in agroindustrial, pharmaceutical, and biomedical fields. Their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling.

Sperm proteases are involved in several gamete interaction events leading to fertilization. This report presents a detailed analysis of the expression and localization of serine protease PRSS38 in human and in mouse spermatozoa and its involvement in fertilization-related events, using bioinformatics, cellular, biochemical, molecular, and functional approaches. Bioinformatics analyses included genomics and data analysis, prediction of protein subcellular localization and post-translational modifications, Self-Organizing Maps (SOMs) unsupervised training with other serine proteases, protein modeling (AlphaFold), and genetic variant analysis. For cellular, biochemical, and functional studies, human semen samples were obtained from healthy normozoospermic volunteers, and epididymal sperm were collected from adult Balb-c/C57 mice. PRSS38 presence was detected in human and mouse sperm protein extracts by Western immunoblotting. Sperm PRSS38 subcellular localization was determined by fluorescence immunocytochemistry. Human sperm-oocyte interaction events were assessed by means of the mouse Cumulus Penetration Assay (CPA) using mouse COCs, the Human Hemizona Assay (HZA), and the ZP-free hamster egg Sperm Penetration Assay (SPA). Mouse sperm-oocyte interactions were evaluated by means of in vitro fertilization (IVF) with COCs and denuded oocytes. PRSS38 is proposed to be a GPI-anchored serine protease (active site: His-100, Asp-150, and Ser-245) based on bioinformatics analyses. Using commercial antibodies, protein forms of the expected Mr (human: 31 kDa; mouse: 32 and 24 kDa) were specifically immunodetected in protein sperm extracts. Immunocytochemical analysis revealed a specific PRSS38 signal in the human sperm acrosomal region, equatorial segment, and flagellum. Mouse sperm PRSS38 was immunolocalized in the equatorial segment and hook. Human sperm preincubation with specific antibodies resulted in inhibition ( < 0.05) of CPA, HZA, and SPA. Mouse sperm preincubation with PRSS38 antibodies impaired ( < 0.05) homologous IVF using COCs and denuded oocytes. Genetic variants affecting residues involved in the GPI anchor and the catalytic triad were found in individuals from the general population whose PRSS38 protease function could be altered. This study provides, for the first time, an integrated analysis of PRSS38 in human and mouse sperm, contributing to our understanding of mammalian fertilization and male infertility.

Upon host penetration, fungal pathogens secrete a plethora of effectors to promote disease, including proteases that degrade plant antimicrobial proteins, and protease inhibitors (PIs) that inhibit plant proteases with antimicrobial activity. Conversely, plants secrete proteases and PIs to protect themselves against pathogens or to mediate recognition of pathogen proteases and PIs, which leads to induction of defense responses. Many examples of proteases and PIs mediating effector-triggered immunity in host plants have been reported in the literature, but little is known about their role in compromising basal defense responses induced by microbe-associated molecular patterns. Recently, several reports appeared in literature on secreted fungal proteases that modify or degrade pathogenesis-related proteins, including plant chitinases or PIs that compromise their activities. This prompted us to review the recent advances on proteases and PIs involved in fungal virulence and plant defense. Proteases and PIs from plants and their fungal pathogens play an important role in the arms race between plants and pathogens, which has resulted in co-evolutionary diversification and adaptation shaping pathogen lifestyles.