Robust anti-inflammatory activity of genistein against neutrophil elastase: a microsecond molecular dynamics simulation study

Human Neutrophil Elastase (HNE) is one of the major causes of tissue destruction in numerous chronic and inflammatory disorders and has been reported as a therapeutic target for inflammatory diseases. Overexpression of this enzyme plays a critical role in the pathogenesis of rheumatoid arthritis (RA). The focus of this study is to identify potent natural inhibitors that could target the active site of the HNE through the use of computational methods. The molecular structure of small molecules was retrieved from several natural compound databases. This was followed by structure-based virtual screening, molecular docking, ADMET property predictions and molecular dynamic simulation studies to screen potential HNE inhibitors. In total, 1881 natural compounds were extracted and subjected to molecular docking studies, and 10 compounds were found to have good interactions, exhibiting the best docking scores. Genistein showed higher binding efficacy (-10.28 Kcal/mol) to HNE in comparison to other natural compounds. The conformational stability of the docked complex of the ELANE gene (HNE) with genistein was assessed using 1-microsecond molecular dynamic simulation (MDs), which reliably revealed the unique stereochemical alteration of the complex, indicating its conformational stability and flexibility. Alterations in the enzyme structure upon complex formation were further characterized through clustering analysis and linear interaction energy (LIE) calculation. The outcomes of this research propose novel potential candidates against target HNE.Communicated by Ramaswamy H. Sarma.

Structural and functional properties of rBmTI-A: A Kunitz-BPTI serine protease inhibitor with therapeutical potential

Serine proteases are an important group of enzymes present in several organisms such as viruses, bacteria and eukaryotes involved in several physiological and pathological processes such as cancer, neurodegeneration, tissue inflammation and infections. Kunitz-type serine protease inhibitors have been studied as therapeutical targets with positive results in many of these diseases. rBmTI-A (recombinant B. microplus Trypsin Inhibitor A) is a Kunitz-BPTI type inhibitor based on the native protein BmTI-A. BmTI-A was extracted from tick larvae and presented inhibitory activity against trypsin, human plasma kallikrein (HuPK), human neutrophil elastase (HNE) and human plasmin. rBmTI-A presented the same inhibitory activities of the BmTI-A and its thermostability has already been demonstrated. In emphysema induced by porcine pancreatic elastase (PPE) and by cigarette smoke animal models, the treatment using rBmTI-A showed a protective effect against the development of pulmonary emphysema and prevented the increase of inflammatory cells. In chronic allergic animal model, rBmTI-A treatment resulted in attenuated bronchial hyperresponsiveness, inflammation, remodeling. These are important physiological results in emphysema and lung inflammatory animal models with rBmTI-A treatment confirming its therapeutical potential.

Dual intra- and extracellular release of monomethyl auristatin E from a neutrophil elastase-sensitive antibody-drug conjugate

Antibody-drug conjugates (ADCs) are targeted therapies, mainly used in oncology, consisting in a three-component molecular architecture combining a highly potent drug conjugated via a linker onto a monoclonal antibody (mAb), designed for the selective delivery of the drug to the tumor site. The linker is a key component, defining the ADC stability and mechanism of action, and particularly the drug release strategy. In this study, we have developed and synthesized a cleavable linker, which possesses an Asn-Pro-Val (NPV) sequence sensitive to the human neutrophil elastase (HNE), overexpressed in the tumor microenvironment. This linker permitted the site-specific conjugation of the cell-permeable drug, monomethyl auristatin E (MMAE), onto trastuzumab, using a disulfide re-bridging technology. The resulting ADC was then evaluated in vitro. This conjugate demonstrated retained antigen (Ag) binding affinity and exhibited high subnanomolar potency against Ag-positive tumor cells after internalization, suggesting an intracellular mechanism of linker cleavage. While no internalization and cytotoxic activity of this ADC was observed on Ag-negative cells in classical conditions, the supplementation of exogenous HNE permitted to restore a nanomolar activity on these cells, suggesting an extracellular mechanism of drug release in these conditions. This in vitro proof of concept tends to prove that the NPV sequence could allow a dual intra- and extracellular mechanism of drug release. This work represents a first step in the design of original ADCs with a new dual intra- and extracellular drug delivery system and opens the way to further experimentations to evaluate their full potential in vivo.

Design of a chromogenic substrate for elastase based on split GFP system-Proof of concept for colour switch sensors

Recent studies have demonstrated that human neutrophil elastase (HNE) can be used as marker for inflammation/infection of chronic wounds since it was found to be present in high concentration in exudate collected from chronic wounds. Biosensors used in wound care benefit from a chromogenic signalling due to the readiness of signal interpretation, but the most common use faint yellow chromogenic molecules such as p-nitroaniline (pNa). In addition, if to be converted into smart dressings, the colour of the detection system should not be masked by the exudate's colour. In this work, we designed a chromogenic substrate for HNE aiming to be incorporated in a smart dressing as a colour switch sensor. The substrate was developed using the GFP-like chromoprotein ultramarine (UM), following the split GFP technology. The cleavage sequence for HNE (Ala-Ala-Pro-Val) was embedded into the sensing moiety of the substrate corresponding to the 11th β-sheet. In the presence of HNE, the 11th β-sheet is able to interact to the signalling moiety composed of the β1-β10 incomplete barrel, allowing the re-establishment of the chromophore environment and, hence, the colour production. Structural homology and molecular dynamics simulations were conducted to aid on the disclosure of the structural changes that are the base of the mechanism of action of this HNE switch substrate. Our findings explore the possible application of GFP-like chromogenic sensors in point-of-care devices for the evaluation of the wounds status, representing a major step in the medical field.

The role of autophagy in the overexpression of MUC5AC in patients with chronic rhinosinusitis

BACKGROUND

Autophagy is a lysosomal degradation pathway that protects the body and is essential for cell survival and differentiation. Mucins (MUCs) are important components of secreted mucus, mucin (MUC)5 AC is the major MUC secreted in the normal airway.

OBJECTIVE

Investigated the role of autophagy in pathogenic mucin (MUC)5 AC production during chronic rhinosinusitis (CRS).

METHODS

The expression of human neutrophil elastase (HNE) and the autophagic proteins microtubule-associated protein 1 light chain (LC)3B-II, c-Jun N-terminal kinase (JNK), c-Jun, and MUC5AC were analyzed in the sinonasal mucosa and human nasal epithelial cells (HNECs) using immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and quantitative real-time polymerase chain reaction (qRT-PCR). Autophagic vacuoles were studied using transmission electron microscopy (TEM). Primary HNECs were treated with HNE, bafilomycin A1, and SP600125. In some experiments, cultured primary HNECs were transfected with small interfering RNAs (siRNAs) to target Beclin-1 (BECN1; BECN1-siRNA), autophagy-related gene 5 (Atg5; Atg5-siRNA), and c-Jun (c-Jun-siRNA). Cultured cells were analyzed using western blotting, qRT-PCR, and ELISA.

RESULTS

In CRS patients, both with and without nasal polyps, the expression levels of HNE, LC3B, JNK, c-Jun, and MUC5AC were upregulated. Bafilomycin A1 upregulated LC3B-II expression and inhibited MUC secretion in HNE-treated normal primary HNECs. Autophagosomes were observed in HNE-treated primary HNECs using TEM. HNE-induced secretion of MUC5AC was suppressed in normal primary HNECs by BECN1-siRNA, Atg5-siRNA, c-Jun-siRNA, and SP600125.

CONCLUSIONS

In HNE-induced CRS, autophagy increases the secretion of MUC5AC by promoting the phosphorylation of JNK and c-Jun.

Detection of human neutrophil elastase (HNE) on wound dressings as marker of inflammation

Chronic wound fluids have elevated concentration of human neutrophil elastase (HNE) which can be used as inflammation/infection marker. Our goal is to develop functional materials for fast diagnosis of wound inflammation/infection by using HNE as a specific marker. For that, fluorogenic peptides with a HNE-specific cleavage sequence were incorporated into traditional textile dressings, to allow real-time detection of the wound status. Two different fluorogenic approaches were studied in terms of intensity of the signal generated upon HNE addition: a fluorophore 7-amino-4-trifluormethylcoumarin (AFC) conjugated to a HNE-specific peptide and two fluorophore/quencher pairs (FAM/Dabcyl and EDANS/Dabcyl) coupled to a similar peptide as a Förster resonance energy transfer (FRET) strategy. Also, two immobilization methods were tested: sonochemistry immobilization onto a cotton bandage and glutaraldehyde (GTA)-assisted chemical crosslinking onto a polyamide dressing. The immobilized fluorogenic AFC peptide showed an intense fluorescence emission in the presence of HNE. HNE also induced an enhanced fluorescent signal with the EDANS/Dabcyl FRET peptide which showed to be a more sensitive and effective strategy than the AFC peptide. However, its chemical immobilization onto the polyamide dressing greatly decreased its detection, mainly due to the more difficult access of the enzyme to the cleavage sequence of the immobilized peptide. After optimization of the in situ immobilization, it will be possible to use these fluorescence-functionalized dressings for an effective and specific monitoring of chronic wounds by simply using a portable ultraviolet (UV) light source. We envision that the development of this point-of-care medical device for wound control will have a great impact on patient's life quality and reduction of costs on health care system.