Discovery of Kasugamycin as a Potent Inhibitor of Glycoside Hydrolase Family 18 Chitinases

Discovery of Rhodanine Inhibitors Targeting Of ChtI Based on the π-Stacking Effect and Aqueous Solubility

The application of some reported inhibitors against the chitinolytic enzyme Of ChtI was limited due to their unsatisfactory insecticidal activities. Hence, we first performed a synergetic design strategy combining the π-stacking effect with aqueous solubility to find novel rhodanine analogues with inhibitory activities against Of ChtI. Novel rhodanine compounds IAa-f and IBa-f have weak aqueous solubility, but they (IAd: Ki = 4.0 μM; IBd: Ki = 2.2 μM) showed better inhibitory activities against Of ChtI and comparable insecticidal efficiency toward Ostrinia furnacalis compared to the high aqueous solubility compounds IIAa-f and IIBa-f (IIAd: Ki = 21.6 μM; IIBd: Ki = 14.3 μM) without a large conjugate plane. Further optimized compounds IIIAa-j with a conjugate plane as well as a higher aqueous solubility exhibited similar good inhibitory activities against Of ChtI (IIIAe: Ki = 2.4 μM) and better insecticidal potency (IIIAe: mortality rate of 63.33%) compared to compounds IAa-f and IBa-f, respectively. Molecular docking studies indicated that the conjugate planarity with the π-stacking effect for rhodanine analogues is responsible for their enzyme inhibitory activity against Of ChtI. This study provides a new strategy for designing insect chitinolytic enzyme inhibitors as insect growth regulators for pest control.

Effects of chitinase-1 inhibitor in obesity-induced and -aggravated asthma in a murine model

AIMS

Despite recent investigations on the role of chitinase in asthma, its role in obesity-induced asthma has not been evaluated. Therefore, we investigated the roles of chitin, chitinase-1, and a chitinase-1 inhibitor (compound X, CPX) in a murine model.

MAIN METHODS

We assigned C57BL/6 mice to the ovalbumin (OVA) model or obesity model group. In the OVA model, mice received intraperitoneal OVA twice within a 2-week interval and intranasal OVA for 3 consecutive days. Additionally, chitin was intranasally administered for 3 consecutive days, and CPX was intraperitoneally injected three times over 5 days. In the obesity model, a high-fat diet (HFD) was maintained for 13 weeks, and CPX was intraperitoneally injected eight times over 4 weeks.

KEY FINDINGS

In the OVA model, chitin aggravated OVA-induced airway hyper-responsiveness (AHR), increased bronchoalveolar lavage fluid (BALF) cell proliferation, increased fibrosis, and increased the levels of various inflammatory cytokines (including chitinase-1, TGF-β, TNF-α, IL-1 β, IL-6, IL-4, and IL-13). CPX treatment significantly ameliorated these effects. In the obesity model, HFD significantly increased AHR, BALF cell proliferation, fibrosis, and the levels of various inflammatory cytokines. Particularly, compared to the control group, the mRNA expression of chitinase, chitinase-like molecules, and other molecules associated with inflammation and the immune system was significantly upregulated in the HFD and HFD/OVA groups. Immunofluorescence analysis also showed increased chitinase-1 expression in these groups. CPX significantly ameliorated all these effects in this model.

SIGNIFICANCE

This study showed that CPX can be an effective therapeutic agent in asthma, especially, obesity-induced and -aggravated asthma to protect against the progression to airway remodeling and fibrosis.

Streptomyces and their specialised metabolites for phytopathogen control - comparative in vitro and in planta metabolic approaches

In the search for new crop protection microbial biocontrol agents, isolates from the genus Streptomyces are commonly found with promising attributes. Streptomyces are natural soil dwellers and have evolved as plant symbionts producing specialised metabolites with antibiotic and antifungal activities. Streptomyces biocontrol strains can effectively suppress plant pathogens via direct antimicrobial activity, but also induce plant resistance through indirect biosynthetic pathways. The investigation of factors stimulating the production and release of Streptomyces bioactive compounds is commonly conducted in vitro, between Streptomyces sp. and a plant pathogen. However, recent research is starting to shed light on the behaviour of these biocontrol agents in planta, where the biotic and abiotic conditions share little similarity to those of controlled laboratory conditions. With a focus on specialised metabolites, this review details (i) the various methods by which Streptomyces biocontrol agents employ specialised metabolites as an additional line of defence against plant pathogens, (ii) the signals shared in the tripartite system of plant, pathogen and biocontrol agent, and (iii) an outlook on new approaches to expedite the identification and ecological understanding of these metabolites under a crop protection lens.

Host chitinase 3-like-1 is a universal therapeutic target for SARS-CoV-2 viral variants in COVID-19

Coronavirus disease 2019 (COVID-19) is the disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2; SC2), which has caused a worldwide pandemic with striking morbidity and mortality. Evaluation of SC2 strains demonstrated impressive genetic variability, and many of these viral variants are now defined as variants of concern (VOC) that cause enhanced transmissibility, decreased susceptibility to antibody neutralization or therapeutics, and/or the ability to induce severe disease. Currently, the delta (δ) and omicron (ο) variants are particularly problematic based on their impressive and unprecedented transmissibility and ability to cause breakthrough infections. The delta variant also accumulates at high concentrations in host tissues and has caused waves of lethal disease. Because studies from our laboratory have demonstrated that chitinase 3-like-1 (CHI3L1) stimulates ACE2 and Spike (S) priming proteases that mediate SC2 infection, studies were undertaken to determine if interventions that target CHI3L1 are effective inhibitors of SC2 viral variant infection. Here, we demonstrate that CHI3L1 augments epithelial cell infection by pseudoviruses that express the alpha, beta, gamma, delta, or omicron S proteins and that the CHI3L1 inhibitors anti-CHI3L1 and kasugamycin inhibit epithelial cell infection by these VOC pseudovirus moieties. Thus, CHI3L1 is a universal, VOC-independent therapeutic target in COVID-19.

Host Chitinase 3-like-1 is a Universal Therapeutic Target for SARS-CoV-2 Viral Variants in COVID 19

COVID 19 is the disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2; SC2) which has caused a world-wide pandemic with striking morbidity and mortality. Evaluation of SC2 strains demonstrated impressive genetic variability and many of these viral variants are now defined as variants of concern (VOC) that cause enhanced transmissibility, decreased susceptibility to antibody neutralization or therapeutics and or the ability to induce severe disease. Currently, the delta (δ) and omicron (o) variants are particularly problematic based on their impressive and unprecedented transmissibility and ability to cause break through infections. The delta variant also accumulates at high concentrations in host tissues and has caused waves of lethal disease. Because studies from our laboratory have demonstrated that chitinase 3-like-1 (CHI3L1) stimulates ACE2 and Spike (S) priming proteases that mediate SC2 infection, studies were undertaken to determine if interventions that target CHI3L1 are effective inhibitors of SC2 viral variant infection. Here we demonstrate that CHI3L1 augments epithelial cell infection by pseudoviruses that express the alpha, beta, gamma, delta or omicron S proteins and that the CHI3L1 inhibitors anti-CHI3L1 and kasugamycin inhibit epithelial cell infection by these VOC pseudovirus moieties. Thus, CHI3L1 is a universal, VOC-independent therapeutic target in COVID 19.