Exploration of the Binding Mechanism of Cyclic Dinucleotide Analogs to Stimulating Factor Proteins and the Implications for Subsequent Analog Drug Design.

Cyclic dinucleotides (CDNs) are cyclic molecules consisting of two nucleoside monophosphates linked by two phosphodiester bonds, which act as a second messenger and bind to the interferon gene stimulating factor (STING) to activate the downstream signaling pathway and ultimately induce interferon secretion, initiating an anti-infective immune response. Cyclic dinucleotides and their analogs are lead compounds in the immunotherapy of infectious diseases and tumors, as well as immune adjuvants with promising applications. Many agonists of pathogen recognition receptors have been developed as effective adjuvants to optimize vaccine immunogenicity and efficacy. In this work, the binding mechanism of human-derived interferon gene-stimulating protein and its isoforms with cyclic dinucleotides and their analogs was theoretically investigated using computer simulations and combined with experimental results in the hope of providing guidance for the subsequent synthesis of cyclic dinucleotide analogs.

Trans-cinnamaldehyde loaded chitosan based nanocapsules display antibacterial and antibiofilm effects against cavity-causing Streptococcus mutans.

Background: Dental caries is a multifactorial disease, and the bacteria such as Streptococcus mutans (S. mutans) is one of the risk factors. The poor effect of existing anti-bacterial is mainly related to drug resistance, the short time of drug action, and biofilm formation. Methods: To address this concern, we report here on the cinnamaldehyde (CA) loaded chitosan (CS) nanocapsules (CA@CS NC) sustained release CA for antibacterial treatment. The size, ζ-potential, and morphology were characterized. The antibacterial activities in vitro were studied by growth curve assay, pH drop assay, biofilm assay, and qRT-PCR In addition, cytotoxicity assay, organ index, body weight, and histopathology results were analyzed to evaluate the safety and biocompatibility in a rat model. Results: CA@CS NC can adsorb the bacterial membrane due to electronic interaction, releasing CA slowly for a long time. At the same time, it has reliable antibacterial activity against S. mutans and downregulated the expression levels of QS, virulence, biofilm, and adhesion genes. In addition, it greatly reduced the cytotoxicity of CA and significantly inhibited dental caries in rats without obvious toxicity. Conclusion: Our results showed that CA@CS NC had antibacterial and antibiofilm effects on S. mutans and inhibit dental caries. Besides, it showed stronger efficacy and less toxicity, and was able to adsorb bacteria releasing CA slowly, providing a new nanomaterial solution for the treatment of dental caries.

Global prevalence and factors affecting the level of Cryptosporidium contamination in soil: A systematic review, meta-analysis, and meta-regression.

Soil contamination with Cryptosporidium is a serious environmental and public health concern. In this systematic review and meta-analysis we estimated the global prevalence of Cryptosporidium contamination in soil and evaluated its association with climatic and hydrometeorological factors. PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure, and Wanfang were searched from database inception up to 24 August 2022. The initial search identified 3220 studies, of which 14 met the inclusion criteria. The results were pooled using a random-effects model, and the statistical heterogeneity among the included studies was examined using Cochrane's Q test and I2 statistic. The estimated pooled global prevalence of Cryptosporidium in soil across all studies was 8.13 % (95 % confidence interval, 1.54-18.44). Meta-regression and subgroup analyses showed that Cryptosporidium prevalence in soil was significantly influenced by continent (p = 0.0002; R2 = 49.99 %), air pressure (p = 0.0154; R2 = 24.01 %), temperature (p = 0.0437; R2 = 14.53 %), and detection method (p = 0.0131; R2 = 26.94 %). These results highlight the need for increased surveillance of Cryptosporidium in soil and its risk factors to inform future development of environmental control interventions and public health policies.

A dual-caged resorufin probe for rapid screening of infections resistant to lactam antibiotics.

The alarming increase of antimicrobial resistance urges rapid diagnosis and pathogen specific infection management. This work reports a rapid screening assay for pathogenic bacteria resistant to lactam antibiotics. We designed a fluorogenic N-cephalosporin caged 3,7-diesterphenoxazine probe CDA that requires sequential activations to become fluorescent resorufin. A series of studies with recombinant ß-lactamases and clinically prevalent pathogens including Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Serratia marcescens demonstrated that CDA possessed superior sensitivity in reporting the activity of ß-lactamases including cephalosporinases and carbapenemases. After a simple filtration, lactam-resistant bacteria in urine samples could be detected at 103 colony-forming units per milliliter within 2 hours.

A small natural molecule CADPE kills residual colorectal cancer cells by inhibiting key transcription factors and translation initiation factors.

Residual disease is the major cause for colorectal cancer (CRC) relapse. Herein, we explore whether and how a natural molecule CADPE killed heterogenic populations in a panel of CRC cell lines with KRAS/BRAF mutations that are natively resistant to EGFR- or VEGFR-targeted therapy, without sparing persistent cells, a reservoir of the disease relapse. Results showed that CADPE killed the tumor bulk and residual cells in the panel of CRC cell lines, rapidly inactivated c-Myc, STAT3, and NF-κB, and then decreased the protein levels of key signaling molecules for CRC, such as ß-catenin, Notch1, and the nodes of mTOR pathways; eukaryotic translation initiation factors (eIF4F); anti-apoptotic proteins (Bcl-xl, Mcl-1, and survivin); and stemness-supporting molecules (CD133, Bim-1, and VEGF). In terms of mechanism of action, concurrent downregulation of Mcl-1, Bcl-xl, and survivin was necessary for CADPE to kill CRC bulk cells, while additional depletion of CD133 and VEGF proteins was required for killing the residual CRC cells. Moreover, the disabled c-Myc, STAT3, NF-κB, and eIF4F were associated with the broadly decreased levels of anti-apoptosis proteins and pro-stemness proteins. Consistently, CADPE suppressed CRC tumor growth associated with robust apoptosis and depleted levels of c-Myc, STAT3, NF-κB, eIF4F, anti-apoptotic proteins, and pro-stemness proteins. Our findings showed the promise of CADPE for treating CRC and suggested a rational polytherapy that disables c-Myc, STAT3, NF-κB, and eIF4F for killing CRC residual disease.

Nitrooxidoreductase Rv2466c-Dependent Fluorescent Probe for Mycobacterium tuberculosis Diagnosis and Drug Susceptibility Testing.

Firstly, this study demonstrated that natural product-inspired coumarin-based nitrofuranyl calanolides (NFCs) can form the Rv2466c-mycothiol (MSH)-NFC (RvMN) ternary complex via NFC binding to W21, N51, and Y61 of Rv2466c and be specifically reduced by Rv2466c, which is accompanied by the generation of a high level of fluorescence. Additionally, the results unveiled that the acetylated cysteine-glucosamine (AcCys-GlcN) motif of MSH is sufficient to interact with Rv2466c and adopt the active conformation that is essential for fully reducing NFCs. Further clinical translational investigation in this Article indicated that the novel fluorescent NFC probe can serve as a much needed high-throughput and low-cost detection method for detection of living Mycobacterium tuberculosis ( Mtb) and can precisely determine MIC values for a full range of available drugs. This method can greatly facilitate the development of phenotypic drug-susceptibility testing (pDST) that will allow the point-of-care treatment of tuberculosis (TB) within a week after diagnosis.

Derivatives of Natural Product Agrimophol as Disruptors of Intrabacterial pH Homeostasis in Mycobacterium tuberculosis.

This article reports the rational medicinal chemistry of a natural product, agrimophol (1), as a new disruptor of intrabacterial pH (pHIB) homeostasis in Mycobacterium tuberculosis (Mtb). Through the systematic investigation of the structure-activity relationship of 1, scaffold-hopping of the diphenylmethane scaffold, pharmacophore displacement strategies, and studies of the structure-metabolism relationship, a new derivative 5a was achieved. Compound 5a showed 100-fold increased potency in the ability to reduce pHIB to pH 6.0 and similarly improved mycobactericidal activity compared with 1 against both Mycobacterium bovis-BCG and Mtb. Compound 5a possessed improved metabolic stability in human liver microsomes and hepatocytes, lower cytotoxicity, higher selectivity index, and similar pKa value to natural 1. This study introduces a novel scaffold to an old drug, resulting in improved mycobactericidal activity through decreasing pHIB, and may contribute to the critical search for new agents to overcome drug resistance and persistence in the treatment of tuberculosis.

[Expression of human beta-defensin 2 and tumor necrosis factor-A in colonic mucosae of ulcerative colitis and diarrhea-predominant irritable bowel syndrome].

OBJECTIVE: To detect the expression of human beta-defensin 2 (HBD-2) and tumor necrosis factor-alpha (TNF-alpha) in the colonic mucosae of ulcerative colitis (UC) patients and diarrhea-predominant irritable bowel syndrome (IBS-D) patients and to evaluate the roles of HBD-2 and TNF-alpha in the pathogenesis and the relationship between them. METHODS: Immunohistochemistry was conducted on the biopsy samples of colonic mucosa from 30 UC patients, 20 IBS-D patients, and 10 normal persons to measure the expression of HBD-2 and TNF-alpha. RESULTS: The expression levels of HBD-2 and TNF-alpha in the colonic mucosa of UC were both significantly higher than those in the colonic mucosa of IBS-D (z = -4.856, z = -3. 987, all P < 0.01) and in the normal colonic mucosa (z = -3.611, z = -3. 248, all P < 0.01). But no significant differences were found between the colonic mucosa of IBS-D and the normal colonic mucosa in the intensity of the expressions of HBD-2 and TNF-alpha (z = -0.373, z = -0.032, all P > 0.05). There were no significant differences in the intensity of the expressions of HBD-2 and TNF-alpha in colonic mucosa of among the mild, moderate, and severe UC (chi2 = 1.190, P > 0.05, chi2 = 1.672, P > 0. 05). CONCLUSION: The expressions of HBD-2 and TNF-at are significantly increased in UC, but are not correlated with IBS-D and the severity of clinical symptoms of UC patients.

Identification of a Mycothiol-Dependent Nitroreductase from Mycobacterium tuberculosis.

The success of Mycobacterium tuberculosis (Mtb) as a pathogen depends on the redundant and complex mechanisms it has evolved for resisting nitrosative and oxidative stresses inflicted by host immunity. Improving our understanding of these defense pathways can reveal vulnerable points in Mtb pathogenesis. In this study, we combined genetic, structural, computational, biochemical, and biophysical approaches to identify a novel enzyme class represented by Rv2466c. We show that Rv2466c is a mycothiol-dependent nitroreductase of Mtb and can reduce the nitro group of a novel mycobactericidal compound using mycothiol as a cofactor. In addition to its function as a nitroreductase, Rv2466c confers partial protection to menadione stress.