Targeting NLRP3 Inflammasome: Structure, Function, and Inhibitors.

Inflammasomes are multimeric protein complexes that can detect various physiological stimuli and danger signals. As a result, they perform a crucial function in the innate immune response. The NLRP3 inflammasome, as a vital constituent of the inflammasome family, is significant in defending against pathogen invasion and preserving cellhomeostasis. NLRP3 inflammasome dysregulation is connected to various pathological conditions, including inflammatory diseases, cancer, and cardiovascular and neurodegenerative diseases. This profile makes NLRP3 an applicable target for treating related diseases, and therefore, there are rising NLRP3 inhibitors disclosed for therapy. Herein, we summarized the updated advances in the structure, function, and inhibitors of NLRP3 inflammasome. Moreover, we aimed to provide an overview of the existing products and future directions for drug research and development.

Hydroxytryptophan biosynthesis by a family of heme-dependent enzymes in bacteria.

Hydroxytryptophan serves as a chemical precursor to a variety of bioactive specialized metabolites, including the human neurotransmitter serotonin and the hormone melatonin. Although the human and animal routes to hydroxytryptophan have been known for decades, how bacteria catalyze tryptophan indole hydroxylation remains a mystery. Here we report a class of tryptophan hydroxylases that are involved in various bacterial metabolic pathways. These enzymes utilize a histidine-ligated heme cofactor and molecular oxygen or hydrogen peroxide to catalyze regioselective hydroxylation on the tryptophan indole moiety, which is mechanistically distinct from their animal counterparts from the nonheme iron enzyme family. Through genome mining, we also identify members that can hydroxylate the tryptophan indole ring at alternative positions. Our results not only reveal a conserved way to synthesize hydroxytryptophans in bacteria but also provide a valuable enzyme toolbox for biocatalysis. As proof of concept, we assemble a highly efficient pathway for melatonin in a bacterial host.

Targeted genome mining for microbial antitumor agents acting through DNA intercalation.

Microbial natural products have been one of the most important sources for drug development. In the current postgenomic era, sequence-driven approaches for natural product discovery are becoming increasingly popular. Here, we develop an effective genome mining strategy for the targeted discovery of microbial metabolites with antitumor activities. Our method employs uvrA-like genes as genetic markers, which have been identified in the biosynthetic gene clusters (BGCs) of several chemotherapeutic drugs of microbial origin and confer self-resistance to the corresponding producers. Through systematic genomic analysis of gifted actinobacteria genera, identification of uvrA-like gene-containing BGCs, and targeted isolation of products from a BGC prioritized for metabolic analysis, we identified a new tetracycline-type DNA intercalator timmycins. Our results thus provide a new genome mining strategy for the efficient discovery of antitumor agents acting through DNA intercalation.

Recent developments in mesoporous polydopamine-derived nanoplatforms for cancer theranostics.

Polydopamine (PDA), which is derived from marine mussels, has excellent potential in early diagnosis of diseases and targeted drug delivery owing to its good biocompatibility, biodegradability, and photothermal conversion. However, when used as a solid nanoparticle, the application of traditional PDA is restricted because of the low drug-loading and encapsulation efficiencies of hydrophobic drugs. Nevertheless, the emergence of mesoporous materials broaden our horizon. Mesoporous polydopamine (MPDA) has the characteristics of a porous structure, simple preparation process, low cost, high specific surface area, high light-to-heat conversion efficiency, and excellent biocompatibility, and therefore has gained considerable interest. This review provides an overview of the preparation methods and the latest applications of MPDA-based nanodrug delivery systems (chemotherapy combined with radiotherapy, photothermal therapy combined with chemotherapy, photothermal therapy combined with immunotherapy, photothermal therapy combined with photodynamic/chemodynamic therapy, and cancer theranostics). This review is expected to shed light on the multi-strategy antitumor therapy applications of MPDA-based nanodrug delivery systems.

Underlying mechanism of sorafenib resistance in hepatocellular carcinoma: a bioinformatics study based on validated resistance-related genes.

BACKGROUND: Sorafenib, the first approved targeted therapy for advanced hepatocellular carcinoma (HCC), is often reported to comprised survival-benefit due to resistance. An underlying mechanism of resistance was proposed using bioinformatics analysis based on differentially expressed genes (DEGs) from microarrays. However, most DEGs were invalidated at both the expression level, and the role in causing resistance. Therefore, we conducted a bioinformatics analysis based on experimentally determined sorafenib-resistance-related genes (SRRGs) to elucidate the mechanism of sorafenib resistance. METHODS: The SRRGs, which have been experimentally determined to promote or inhibit resistance, were collected from published studies. The Database for Annotation, Visualization and Integrated Discovery (DAVID) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to perform Gene Ontology (GO) and pathway enrichment analysis, respectively. A corresponding protein-protein interaction network (PPI) was created using the Cytoscape software program, and network hub genes were proposed. RESULTS: A total of 145 SRRGs, with 117 promoting and 28 inhibiting resistance, were identified. Cell proliferation, migration, development, response to oxygen levels, epithelial-to-mesenchymal transition (EMT), cell skeleton, protein function, and autophagy were all proposed as crucial gene functions related to resistance. The pathways related to cell proliferation or apoptosis, immune function, endocrine metabolism, stem cell function, and differentiation were identified as key resistance-related pathways. A total of 81 hub genes were proposed, including the following top 10 genes: TP53, AKT1, EGFR, STAT3, VEGFA, JUN, MAPK1, IL6, PTEN, and CTNNB1. CONCLUSIONS: In conclusion, this study gathered experimentally validated genes that determine sorafenib resistance in HCC, provided an overview of the underlying mechanisms of resistance, and further validated sorafenib resistance in HCC.

Evaluation of Concentration Errors and Inappropriate Dose Tailoring of Tacrolimus Caused by Sampling-Time Deviations in Pediatric Patients With Primary Nephrotic Syndrome.

BACKGROUND: Tacrolimus dosing is routinely tailored based on its trough level (C0) drawn by therapeutic drug monitoring in pediatric patients with primary nephrotic syndrome. However, this concentration is often inaccurate owing to inappropriate practice, such as deviation of sampling time (DST). The quantitative relationship between DST and C0 remains unclear. METHODS: Tacrolimus concentration at nominal sampling times (12 hours after last dose) and 32 deviation scenarios (12 ± 4 hours every 15 minutes) was predicted using a previously validated population pharmacokinetic model based on 162 scenarios of 100 primary nephrotic syndrome patients involved in the population pharmacokinetic model and derived virtual patients. Concentration error (CE) and relative CE (RCE) were evaluated, and the correlation between DST and RCE was evaluated by subgroup analysis using linear regression. Ultimately, the inappropriate dosing possibly misled by incorrect C0 was simulated in a real-patient cohort according to the target range (5-10 ng/mL). RESULTS: Approximately 7% of RCE was caused at every 1-hour of DST. DST was the most major contributor of RCE (r = 0.773-0.804). Patients with early sampling, older age, high body weight, high dose, low aspartate transaminase level, high corticosteroid dose, and without combination of azole antifungal agents were revealed to have high RCE. Approximately 7%-36% and 9%-25% of inappropriate dose tailoring may be caused by early and delayed sampling, respectively. In addition, patients with early sampling or high-dose tacrolimus had a higher risk of inappropriate dosing than patients with delayed sampling [hazard ratio = 1.53, 95% confidence interval (CI): 1.03-2.27, P = 0.048], and low-dose tacrolimus (P < 0.0001). CONCLUSIONS: A moderate bias of concentration and dose tailoring was revealed within 4 hours of DST. In addition, a high risk of bias was found in patients with early sampling and high-dose tacrolimus.

Retrospective analysis of tigecycline shows that it may be an option for children with severe infections.

AIM: This study assessed the efficacy and safety of tigecycline in children with life-threatening infections. METHODS: We retrospectively reviewed the clinical records of patients treated with tigecycline from June 2012 to May 2014 in a Chinese tertiary centre. RESULTS: The study comprised 24 patients (14 male) with a median age of four years (range, 50 days-12 years). The most frequently isolated microorganism, most common isolation site and type of infection were Acinetobacter baumannii, tracheal aspirate fluid and ventilator-associated pneumonia, respectively. Tigecycline was administered at a loading dose of 1.5 or 2.0 mg/kg and 1.0 mg/kg every 12 hours after that. The average duration of treatment was 11.6 ± 5.8 days. The clinical response and microbiological eradication rate were 37.5% and 29.2%, respectively. Six of the patients we studied (25.0%) died, and three of these deaths were considered to be infection related. Adverse drug reactions were identified in four patients (16.7%) during the treatment, including abnormal liver function, prolonged prothrombin time and diarrhoea. CONCLUSION: Our findings suggest that tigecycline may be an option for children with severe infections. However, more prospective, controlled trials are required to objectively evaluate the efficacy and safety of tigecycline in children.