Identification and characterization of aptameric inhibitors of human neutrophil elastase

ASK1 inhibition by selonsertib attenuates elastase-induced emphysema in mice

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, with its most severe form being pulmonary emphysema, for which no effective treatment currently exists. Apoptosis signal-regulating kinase 1 (ASK1) has been implicated in lung inflammation and injury. Here, we investigated the experimental treatment of elastase-induced emphysema in mice with selonsertib, an ASK1 inhibitor. Animals received intratracheal elastase and were subsequently treated with intranasal selonsertib at different doses. On day 21, bronchoalveolar lavage fluid and lung tissues were collected for histological and biochemical analyses. Results showed that elastase-instilled mice developed pulmonary emphysema, whereas treatment with selonsertib at a dose of 2 mg/kg significantly reduced mean alveolar diameter. Moreover, higher doses of selonsertib were effective in reducing inflammatory cytokines (CX3CL1, IL-6, CCL2, and IL-1β), reactive oxygen species, and apoptosis. These findings suggest that ASK1 plays a critical role in the development of elastase-induced emphysema in mice and could be a target for COPD treatment.

Chemical annotation of the infusion of Jungia floribunda Less and its inhibitory potential on the elastase enzyme

Jungia floribunda Less. is a shrub belonging to the Asteraceae. The infusion of its leaves has been used, in folk medicine of several South American countries, as anti-inflammatory and hypoglycaemic agent. In the present study, the infusion of leaves from J. floribunda was obtained and its chemical composition was determined by UHPLC-MS associated with molecular network allowing the annotation of flavonoids, sesquiterpene lactones, coumarins, and chlorogenic acid derivatives. Besides, in vitro elastase activity assay was carried out with the infusion. As observed, elastase was inhibited at concentrations ranging from 15 to 240 µg/mL, reaching to 71% of inhibition at the maximum of evaluated concentration. Given that species of plants are promising sources for the discovery of new drugs, these results corroborate the infusion of J. floribunda as a potential source of bioactive compounds for the discovery of new inhibitors for elastase, besides its ethnopharmacological aspects.

Bidirectional Enzyme Inhibition and Activation for In Situ Formation of Injectable Hydrogel Using a Bispecific Aptamer

In situ injectable hydrogels have been explored for biomedical applications, including regenerative medicine and drug delivery. However, controlling the kinetics of their gelation to facilitate easy injection remains a challenge. The purpose of this study was to demonstrate the potential of using bispecific aptamers and complementary sequences as a bidirectional modulation system for controlling enzyme-mediated hydrogel formation kinetics. The results show that a bispecific thrombin-binding aptamer effectively inhibits thrombin activity and significantly slowed fibrin hydrogel formation. Upon interaction with its complementary sequence, this inhibition could be reversed. As a result, the aptamer-bound thrombin was activated, leading to an acceleration of the fibrin formation kinetics. Thus, bispecific aptamers and complementary sequences can effectively function as dynamic control systems for enzyme-catalyzed in situ injectable hydrogel formation.

Enzymatic, structural, and biophysical characterization of a single-domain antibody (VHH) selectively and tightly inhibiting neutrophil elastase and exhibiting favorable developability properties

Human neutrophil elastase (hNE), a serine protease released by neutrophils during inflammation, plays a major role in the pathophysiology of several conditions especially in inflammatory lung diseases. Its inhibition constitutes, therefore, a promising therapeutic strategy to combat these diseases. In this work, we characterized the in vitro properties of a VHH (i.e., the antigen binding domain of camelid heavy chain-only antibodies), referred to as NbE201. This VHH is able to inhibit tightly, selectively and competitively both human and murine elastases with the inhibition constants (Ki) of 4.1 ± 0.9 nM and 36.8 ± 3.9 nM, respectively. The IC50 for the inhibition of the hydrolysis of elastin is in the same range to that of alpha-1 antitrypsin (i.e., the main endogenous inhibitor of hNE also used in the clinic) and 14 times better than that of Sivelestat (i.e., the 2nd clinically approved hNE inhibitor). The X-ray crystal structure of the NbE201-hNE complex reveals that the Complementarity Determining Regions CDR1 and CDR3 of the VHH bind into the substrate binding pocket of hNE and prevent the access to small or macromolecular substrates. They do not, however, bind deep enough into the pocket to be hydrolyzed. NbE201 is highly stable towards oxidation, deamidation, and chemical or thermal denaturation. NbE201 is therefore likely to tolerate manufacturing processes during drug development. These results highlight the high potential of NbE201 as a (pre)clinical tool to diagnose and treat diseases associated with excessive hNE activity, and for fundamental research to better understand the role of hNE in these conditions.

Screening and characterization of aptamers recognizing the periodontal pathogen Tannerella forsythia

Periodontal disease is one of the most common forms of inflammation. It is currently diagnosed by observing symptoms such as gingival bleeding and attachment loss. However, the detection of biomarkers that precede such symptoms would allow earlier diagnosis and prevention. Aptamers are short oligonucleotides or peptides that fold into three-dimensional conformations conferring the ability to bind molecular targets with high affinity and specificity. Here we report the selection of aptamers that bind specifically to the bacterium Tannerella forsythia, a pathogen frequently associated with periodontal disease. Two aptamers with the highest affinity were examined in more detail, revealing that their binding is probably dependent on mirolysin, a surface-associated protease secreted by the T. forsythia type-9 secretion system. The aptamers showed minimal cross-reactivity to other periodontopathogens and are therefore promising leads for the development of new tools to study the composition of the periodontitis-associated dysbiotic bacteriome as well as inexpensive new diagnostic assays.