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[
Parasitol Res,
1988]
The rate of transmammary transmission of Stronglyloides ratti was examined in albino rats in terms of the route of subcutaneous (s.c.) migration from the infection site (the skin) to the cranium. Inoculation sites nearer the cranium resulted in less frequent transmammary infection. The maximum number of adult worms was recovered from the sucklings when the mother was inoculated in her hindquarter and sucklings were allowed to feed for 30-36 h after inoculation (AI). Few worms were recovered from sucklings when they were allowed to nurse during periods of less than 24 h AI or greater than 42 h AI. In lactating mothers, larval infection of the mammary glands was commonly observed, and these larvae showed an increased esophagus length. In nonlactating mothers, most larvae completed their migration to the cranium within 36 h AI.
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[
ACS Chem Biol,
2013]
The cell utilizes the Keap1/Nrf2-ARE signaling pathway to detoxify harmful chemicals in order to protect itself from oxidative stress and to maintain its reducing environment. When exposed to oxidative stress and xenobiotic inducers, the redox sensitive Keap1 is covalently modified at specific cysteine residues. Consequently, the latent transcription factor Nrf2 is stabilized and translocates into the nucleus, where it transactivates the expression of detoxification genes through binding to the antioxidant response element (ARE). In the pursuit of potent and bioavailable activators of the ARE, we validated hits from a pathway-directed high-throughput screening campaign by testing them in cell culture and a reporter strain of a whole animal model, Caenorhabditis elegans. These studies allowed us to identify AI-3 as an ARE activator that induces cytoprotective genes in human cells and in worms, which also translated into in vivo activity in mice. AI-3 is an electrophilic ARE activator with two thiol sensitive sites toward a nucleophilic aromatic substitution, and SAR studies indicated the tunability of the system. Tandem LC-MS analysis revealed that AI-3 alkylates Keap1 primarily at Cys151, while AI-3 is reactive toward additional cysteine residues at higher doses in vitro and in vivo. The immediate effects of such alkylation included the disruption of Keap1-Cul3 (low [AI-3]) and/or Keap1-Nrf2 (high [AI-3]) interactions that both led to the stabilization of Nrf2. This further translated into the downstream Nrf2-ARE regulated cytoprotective gene activation. Collectively, AI-3 may become a valuable biological tool and may even provide therapeutic benefits in oxidative stress related diseases.
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[
FEMS Microbiol Lett,
2011]
Broccoli extract (BE) has numerous beneficial effects on human health including anticancer activity. Quorum sensing (QS), mediated by self-produced autoinducer (AI) molecules, is a key process for the production of virulence determinants in pathogenic bacteria. BE suppressed AI-2 synthesis and AI-2-mediated bacterial motility in a dose-dependent manner in Escherichia coli O157:H7. In addition, expression of the ler gene that regulates AI-3 QS system was also diminished in response to treatment with BE. Furthermore, in an in vivo efficacy test using Caenorhabditis elegans as a host organism, C. elegans fed on E. coli O157:H7 in the presence of BE survived longer than those fed solely on the pathogenic bacteria. Quantitative real-time PCR analysis indicated that quercetin was the most active among the tested broccoli-derived compounds in downregulating virulence gene expression, while treatment with myricetin significantly suppressed the expression of the eae gene involved in type III secretion system. These data suggest that BE and its flavonoid constituents can inhibit expression of QS-associated genes, thereby downregulating the virulence attributes of E. coli O157:H7 both in vitro and in vivo. This study clearly elucidates BE's QS-inhibitory activity and suggests that BE has the potential to be developed as an anti-infective agent.
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Cell Host Microbe,
2017]
Microbes affect drug responses, but mechanisms remain elusive. Two papers in Cell exploit C.elegans to infer anticancer drug mechanisms. Through high-throughput screens of drug-microbe-host interactions, Garcia-Gonzalez etal. (2017) and Scott etal. (2017) determine that bacterial metabolism underpins fluoropyrimidine cytotoxicity, providing a paradigm for unraveling bacterial mechanisms in drug metabolism.
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Xiao J, Zhao M, Zhang Y, Jiang K, Luo R, Lin F, Wang L, Yue Y, Wu H, Yuan B, Xu Y
[
Front Microbiol,
2022]
Bacterial drug resistance caused by overuse and misuse of antibiotics is common, especially in clinical multispecies infections. It is of great significance to discover novel agents to treat clinical bacterial infections. Studies have demonstrated that autoinducer-2 (AI-2), a signal molecule in quorum sensing (QS), plays an important role in communication among multiple bacterial species and bacterial drug-resistance. Previously, 14 AI-2 inhibited compounds were selected through virtual screening by using the AI-2 receptor protein LuxP as a target. Here, we used Vibrio harveyi BB170 as a reporter strain for the preliminary screening of 14 inhibitors and compound Str7410 had higher AI-2 QS inhibition activity (IC50 = 0.3724 +/- 0.1091 μM). Then, co-culture of Pseudomonas aeruginosa PAO1 with Staphylococcus aureus ATCC 25923 was used to evaluate the inhibitory effects of Str7410 on multispecies infection in vitro and in vivo. In vitro, Str7410 significantly inhibited the formation of mixed bacterial biofilms. Meanwhile, the combination of Str7410 with meropenem trihydrate (MEPM) significantly improved the susceptibility of mixed-species-biofilm cells to the antibiotic. In vivo, Str7410 significantly increased the survival rate of wild-type Caenorhabditis elegans N2 co-infected by P. aeruginosa PAO1 and S. aureus ATCC 25923. Real-time quantitative PCR analysis showed that Str7410 reduced virulence factor (pyocyanin and elastase) production and swarming motility of P. aeruginosa PAO1 by downregulating the expression of QS-related genes in strain PAO1 in co-culture with S. aureus ATCC 25923. Compound Str7410 is a candidate agent for treating drug-resistant multispecies infections. The work described here provides a strategy for discovering novel antibacterial drugs.
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[
Geroscience,
2023]
Targeting aging is the future of twenty-first century preventative medicine. Small molecule interventions that promote healthy longevity are known, but few are well-developed and discovery of novel, robust interventions has stagnated. To accelerate longevity intervention discovery and development, high-throughput systems are needed that can perform unbiased drug screening and directly measure lifespan and healthspan metrics in whole animals. C. elegans is a powerful model system for this type of drug discovery. Combined with automated data capture and analysis technologies, truly high-throughput longevity drug discovery is possible. In this perspective, we propose the "million-molecule challenge", an effort to quantitatively assess 1,000,000 interventions for longevity within five years. The WormBot-AI, our best-in-class robotics and AI data analysis platform, provides a tool to achieve the million-molecule challenge for pennies per animal tested.
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Fang EF, Liu BHM, Leung GHD, Lautrup S, Wong CW, Izumchenko E, Schmauck-Medina T, Rosenberg AJ, Rice J, Ren F, Ozerov IV, Aliper A, Pun FW, Long X, Leung HW, Zhavoronkov A, Agrawal N
[
Aging Cell,
2023]
As aging and tumorigenesis are tightly interconnected biological processes, targeting their common underlying driving pathways may induce dual-purpose anti-aging and anti-cancer effects. Our transcriptomic analyses of 16,740 healthy samples demonstrated tissue-specific age-associated gene expression, with most tumor suppressor genes downregulated during aging. Furthermore, a large-scale pan-cancer analysis of 11 solid tumor types (11,303 cases and 4431 control samples) revealed that many cellular processes, such as protein localization, DNA replication, DNA repair, cell cycle, and RNA metabolism, were upregulated in cancer but downregulated in healthy aging tissues, whereas pathways regulating cellular senescence were upregulated in both aging and cancer. Common cancer targets were identified by the AI-driven target discovery platform-PandaOmics. Age-associated cancer targets were selected and further classified into four groups based on their reported roles in lifespan. Among the 51 identified age-associated cancer targets with anti-aging experimental evidence, 22 were proposed as dual-purpose targets for anti-aging and anti-cancer treatment with the same therapeutic direction. Among age-associated cancer targets without known lifespan-regulating activity, 23 genes were selected based on predicted dual-purpose properties. Knockdown of histone demethylase KDM1A, one of these unexplored candidates, significantly extended lifespan in Caenorhabditis elegans. Given KDM1A's anti-cancer activities reported in both preclinical and clinical studies, our findings propose KDM1A as a promising dual-purpose target. This is the first study utilizing an innovative AI-driven approach to identify dual-purpose target candidates for anti-aging and anti-cancer treatment, supporting the value of AI-assisted target identification for drug discovery.
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[
J Food Sci,
2015]
Clostridium difficile infection (CDI) is the most prevalent cause of health-care-associated infections. CDI-related health-care costs and deaths are both increasing annually on a global scale. C. difficile have been reported in food products in Canada, Europe, and the United States; however, the systematic transmission of C. difficile between humans and animals is yet to be understood. Because of the limitations of current therapeutic options, there is a need for the development of new patient treatments. Epigallocatechin gallate (EGCG) is a major catechin compound found in green tea extracts and exhibits antioxidant and antimicrobial activities. This study was conducted to investigate the inhibitory effects of EGCG on the expression of virulence genes in C. difficile and in C. difficile-associated diseases by inhibition of quorum sensing. The protein expression of autoinducer-2 (AI-2) was evaluated by AI-2 activity. EGCG at various concentrations had an inhibitory effect on AI-2 production, especially at 10 g/mL. EGCG also significantly repressed the transcription of virulence genes, including luxS and tcdA, and prolonged the survival of Caenorhabditis elegans infected with C. difficile. Furthermore, treatment with EGCG effectively protected C. difficile-infected mice from C. difficile-induced death. Histological analysis of the colon and cecum of these mice revealed that EGCG protected tissues of the lower intestinal tract from damage. EGCG exerted growth-inhibitory and bactericidal activities on C. difficile in C. difficile-infected mice. Our results suggest that EGCG has significant antipathogenic effects on C. difficile and can be used to prevent or treat C. difficile-associated diseases or C. difficile infections.
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[
Anaerobe,
2012]
The effect of Bifidobacterium spp. on the production of quorum-sensing (QS) signals and biofilm formation by enterohemorrhagic Escherichia coli (EHEC) O157:H7 was investigated. In an AI-2 bioassay, cell extracts of Bifidobacterium longum ATCC 15707 resulted in a 98-fold reduction in AI-2 activity in EHEC O157:H7 as well as in the Vibrio harveyi reporter strain, even though they did not inhibit the growth of EHEC O157:H7. In addition, they resulted in a 36% reduction in biofilm formation by the organism. Consistently, the virulence of EHEC O157:H7 was significantly attenuated by the presence of cell extracts of B.longum ATCC 15707 in the Caenorhabditis elegans nematode invivo model. By a proteome analysis using two dimensional electrophoresis (2-DE), we determined that seven proteins including formation of iron-sulfur protein (NifU), thiol:disulfide interchange protein (DsbA), and flagellar P-ring protein (FlgI) were differentially regulated in the EHEC O157:H7 when supplemented with cell extracts of B.longum ATCC 15707. Taken together, these findings propose a novel function of a dairy adjunct in repressing the virulence of EHEC O157:H7.
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[
PLoS One,
2014]
In the present study we show that luxS of Bifidobacterium breve UCC2003 is involved in the production of the interspecies signaling molecule autoinducer-2 (AI-2), and that this gene is essential for gastrointestinal colonization of a murine host, while it is also involved in providing protection against Salmonella infection in Caenorhabditis elegans. We demonstrate that a B. breve luxS-insertion mutant is significantly more susceptible to iron chelators than the WT strain and that this sensitivity can be partially reverted in the presence of the AI-2 precursor DPD. Furthermore, we show that several genes of an iron starvation-induced gene cluster, which are downregulated in the luxS-insertion mutant and which encodes a presumed iron-uptake system, are transcriptionally upregulated under in vivo conditions. Mutation of two genes of this cluster in B. breve UCC2003 renders the derived mutant strains sensitive to iron chelators while deficient in their ability to confer gut pathogen protection to Salmonella-infected nematodes. Since a functional luxS gene is present in all tested members of the genus Bifidobacterium, we conclude that bifidobacteria operate a LuxS-mediated system for gut colonization and pathogen protection that is correlated with iron acquisition.