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Iso-Migrastatin (iso-MGS) and lactimidomycin (LTM) are glutarimide-containing polyketide natural products (NPs) that are biosynthesized by homologous acyltransferase (AT)-less type I polyketide synthase (PKS) assembly lines. The biological activities of iso-MGS and LTM have inspired numerous efforts to generate analogues via genetic manipulation of their biosynthetic machinery in both native producers and model heterologous hosts. A detailed understanding of the MGS and LTM AT-less type I PKSs would serve to inspire future engineering efforts while advancing the fundamental knowledge of AT-less type I PKS enzymology. The mgs and ltm biosynthetic gene clusters (BGCs) encode for two discrete ATs of the architecture AT-enoylreductase (AT-ER) and AT-type II thioesterase (AT-TE). Herein, we report the functional characterization of the mgsB and ltmB and the mgsH and ltmH gene products, revealing that MgsB and LtmB function as type II thioesterases (TEs) and MgsH and LtmH are the dedicated trans-ATs for the MGS and LTM AT-less type I PKSs. In vivo and in vitro experiments demonstrated that MgsB was devoid of any AT activity, despite the presence of the conserved catalytic triad of canonical ATs. Cross-complementation experiments demonstrated that MgsH and LtmH are functionally interchangeable between the MGS and LTM AT-less type I PKSs. This work sets the stage for future mechanistic studies of AT-less type I PKSs and efforts to engineer the MGS and LTM AT-less type I PKS assembly lines for novel glutarimide-containing polyketides.
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BACKGROUND: Obesity is a risk factor for colorectal cancer (CRC). The role of gut microbiota in mediating the cancer-promoting effect of obesity is unknown. METHODS: Azoxymethane (AOM)-treated, ApcMin/+ and germ-free mice were gavaged with feces from obese individuals and control subjects respectively. The colonic tumor load and number were recorded at the endpoint in two carcinogenic models. The gut microbiota composition and colonic transcriptome were assessed by metagenomic sequencing and RNA sequencing, respectively. The anticancer effects of bacteria depleted in fecal samples of obese individuals were validated. FINDINGS: Conventional AOM-treated and ApcMin/+ mice receiving feces from obese individuals showed significantly increased colon tumor formation compared with those receiving feces from control subjects. AOM-treated mice receiving feces from obese individuals showed impaired intestinal barrier function and significant upregulation of pro-inflammatory cytokines and activation of oncogenic Wnt signaling pathway. Consistently, transferring feces from obese individuals to germ-free mice led to increased colonic cell proliferation, intestinal barrier function impairment, and induction of oncogenic and proinflammatory gene expression. Moreover, germ-free mice transplanted with feces from obese human donors had increased abundance of potential pathobiont Alistipes finegoldii, and reduced abundance of commensals Bacteroides vulgatus and Akkermansia muciniphila compared with those receiving feces from human donors with normal body mass index (BMI). Validation experiments showed that B. vulgatus and A. muciniphila demonstrated anti-proliferative effects in CRC, while A. finegoldii promoted CRC tumor growth. INTERPRETATION: Our results supported the role of obesity-associated microbiota in colorectal carcinogenesis and identified putative bacterial candidates that may mediate its mechanisms. Microbiota modulation in obese individuals may provide new approaches to prevent or treat obesity-related cancers including CRC. FUNDING: This work was funded by National Key Research and Development Program of China (2020YFA0509200/2020YFA0509203), National Natural Science Foundation of China (81922082), RGC Theme-based Research Scheme Hong Kong (T21-705/20-N), RGC Research Impact Fund Hong Kong (R4632-21F), RGC-CRF Hong Kong (C4039-19GF and C7065-18GF), RGC-GRF Hong Kong (14110819, 14111621), and NTU Start-Up Grant (021337-00001).
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Neoplasias del Colon , Neoplasias Colorrectales , Microbioma Gastrointestinal , Humanos , Ratones , Animales , Carcinogénesis , Obesidad/complicaciones , Azoximetano/toxicidad , Neoplasias Colorrectales/genética , Ratones Endogámicos C57BL , Modelos Animales de EnfermedadRESUMEN
Emerging evidence of an altered gut microbiome in autism spectrum disorder (ASD) suggests a pathomechanism through the gut-brain axis despite the inconsistent microbiome profile reported across studies. One of the knowledge gaps in the existing ASD microbiota studies is the lack of systematic exploration of the role of comorbid functional gastrointestinal disorder (FGID) in the association of ASD and altered gut microbiome. Consequently, 92 ASD and 112 age-matched typically developing (TD) boys were profiled on general psychopathology, FGID status by Rome IV classification, and gut microbiota using 16S ribosomal RNA amplicon sequencing at the V4 hypervariable region. Compared to TD, a significant decrease in the within-sample abundance of taxa was observed in ASD, regardless of FGID status. The microbiota of ASD FGID+ and ASD FGID- clustered apart from the TD groups. The microbiota of ASD FGID+ also showed qualitative differences from that of ASD FGID- and had the highest-level Firmicutes: Bacteroidetes ratio, which was paralleled by elevated levels of anxiety and overall psychopathology. The altered gastrointestinal microbiota composition in ASD appeared to be independent of comorbid FGID. Further studies should address how FGID may mediate neuropsychiatric symptoms in ASD through inflammation along the microbiota-gut-brain axis.
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Trastorno del Espectro Autista , Trastorno Autístico , Enfermedades Gastrointestinales , Microbioma Gastrointestinal , Estudios de Casos y Controles , China , Microbioma Gastrointestinal/genética , Humanos , MasculinoRESUMEN
BACKGROUND & AIMS: The enteric mycobiota is a major component of the human gut microbiota, but its role in colorectal cancer (CRC) remains largely elusive. We conducted a meta-analysis to uncover the contribution of the fungal mycobiota to CRC. METHODS: We retrieved fecal metagenomic data sets from 7 previous publications and established an additional in-house cohort, totaling 1329 metagenomes (454 with CRC, 350 with adenoma, and 525 healthy individuals). Mycobiota composition and microbial interactions were analyzed. Candidate CRC-enriched fungal species (Aspergillus rambellii) was functionally validated in vitro and in vivo. RESULTS: Multicohort analysis revealed that the enteric mycobiota was altered in CRC. We identified fungi that were associated with patients with CRC or adenoma from multiple cohorts. Signature CRC-associated fungi included 6 enriched (A rambellii, Cordyceps sp. RAO-2017, Erysiphe pulchra, Moniliophthora perniciosa, Sphaerulina musiva, and Phytophthora capsici) and 1 depleted species (A kawachii). Co-occurrent interactions among CRC-enriched fungi became stronger in CRC compared with adenoma and healthy individuals. Moreover, we reported the transkingdom interactions between enteric fungi and bacteria in CRC progression, of which A rambellii was closely associated with CRC-enriched bacteria Fusobacterium nucleatum. A rambellii promoted CRC cell growth in vitro and tumor growth in xenograft mice. We further identified that combined fungal and bacterial biomarkers were more accurate than panels with pure bacterial species to discriminate patients with CRC from healthy individuals (the area under the curve relative change increased by 1.44%-10.60%). CONCLUSIONS: This study reveals enteric mycobiota signatures and pathogenic fungi in stages of colorectal tumorigenesis. Fecal fungi can be used, in addition to bacteria, for noninvasive diagnosis of patients with CRC.
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Adenoma , Neoplasias Colorrectales , Adenoma/microbiología , Animales , Aspergillus , Bacterias/genética , Biomarcadores , Transformación Celular Neoplásica , Neoplasias Colorrectales/diagnóstico , Heces/microbiología , Humanos , Metagenoma , RatonesRESUMEN
Clostridioides difficile infection (CDI) is a common cause of nosocomial diarrhea. TcdB is a major C. difficile exotoxin that activates macrophages to promote inflammation and epithelial damage. Lysosome impairment is a known trigger for inflammation. Herein, we hypothesize that TcdB could impair macrophage lysosomal function to mediate inflammation during CDI. Effects of TcdB on lysosomal function and the downstream pro-inflammatory SQSTM1/p62-NFKB (nuclear factor kappa B) signaling were assessed in cultured macrophages and in a murine CDI model. Protective effects of two lysosome activators (i.e., vitamin D3 and carbamazepine) were assessed. Results showed that TcdB inhibited CTNNB1/ß-catenin activity to downregulate MITF (melanocyte inducing transcription factor) and its direct target genes encoding components of lysosomal membrane vacuolar-type ATPase, thereby suppressing lysosome acidification in macrophages. The resulting lysosomal dysfunction then impaired autophagic flux and activated SQSTM1-NFKB signaling to drive the expression of IL1B/IL-1ß (interleukin 1 beta), IL8 and CXCL2 (chemokine (C-X-C motif) ligand 2). Restoring MITF function by enforced MITF expression or restoring lysosome acidification with 1α,25-dihydroxyvitamin D3 or carbamazepine suppressed pro-inflammatory cytokine expression in vitro. In mice, gavage with TcdB-hyperproducing C. difficile or injection of TcdB into ligated colon segments caused prominent MITF downregulation in macrophages. Vitamin D3 and carbamazepine lessened TcdB-induced lysosomal dysfunction, inflammation and histological damage. In conclusion, TcdB inhibits the CTNNB1-MITF axis to suppress lysosome acidification and activates the downstream SQSTM1-NFKB signaling in macrophages during CDI. Vitamin D3 and carbamazepine protect against CDI by restoring MITF expression and lysosomal function in mice.Abbreviations: ATP6V0B: ATPase H+ transporting V0 subunit b; ATP6V0C: ATPase H+ transporting V0 subunit c; ATP6V0E1: ATPase H+ transporting V0 subunit e1; ATP6V1H: ATPase H+ transporting V1 subunit H; CBZ: carbamazepine; CDI: C. difficile infection; CXCL: chemokine C-X-X motif ligand; IL: interleukin; LAMP1: lysosomal-associated membrane protein 1; LC3: microtubule-associated protein 1 light chain 3; LEF: lymphoid enhancer binding factor 1; MITF: melanocyte inducing transcription factor; NFKB: nuclear factor kappa B; PMA: phorbol 12-myristate 13-acetate; TcdA: Clostridial toxin A; TcdB: Clostridial toxin B; TFE3: transcription factor E3; TFEB: transcription factor EB.
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Toxinas Bacterianas , Clostridioides difficile , Infecciones por Clostridium , ATPasas de Translocación de Protón Vacuolares , Animales , Autofagia , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/farmacología , Carbamazepina/metabolismo , Carbamazepina/farmacología , Colecalciferol/farmacología , Infecciones por Clostridium/metabolismo , Concentración de Iones de Hidrógeno , Inflamación/metabolismo , Lisosomas/metabolismo , Macrófagos/metabolismo , Ratones , FN-kappa B/metabolismo , Proteína Sequestosoma-1/metabolismo , ATPasas de Translocación de Protón Vacuolares/metabolismoRESUMEN
Colorectal cancer (CRC) is a heterogeneous disease with different gene expression patterns. There are two major colorectal carcinogenesis pathways: conventional adenoma-carcinoma pathway and alternative serrated neoplasia pathway. Apart from the conventional pathway that is typically initiated by characteristic APC mutation and chromosomal instability, the serrated neoplasia pathway is mainly characterized by mutations of BRAF or KRAS, microsatellite instability (MSI), and CpG island methylator phenotype (CIMP). Despite the malignant potential of serrated lesions, they can be easily overlooked during endoscopy screening and even in pathological assessment due to its anatomical location, morphology, and histological features. It has been shown that environmental factors especially the gut microbial composition play a key role in CRC pathogenesis. Thus, the preferential localization of serrated lesions in specific intestine areas suggest that niche-specific microbiota composition might intertwined with host genetic perturbations during the development of serrated lesions. Although serrated lesions and conventional adenomas are biologically different, most studies have focused on conventional adenomas, while the pathophysiology and role of microorganisms in the development of serrated lesions remain elusive. In this review, we discuss on the role of gut microbiota in the serrated neoplasia pathway of colorectal carcinogenesis and its specific clinical and molecular features, and summarize the potential mechanisms involved.
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Neoplasias Colorrectales/genética , Neoplasias Colorrectales/microbiología , Microbioma Gastrointestinal , Lesiones Precancerosas/genética , Lesiones Precancerosas/microbiología , Adenoma/genética , Adenoma/microbiología , Adenoma/patología , Carcinogénesis , Neoplasias Colorrectales/patología , Disbiosis , Humanos , Mutación , Lesiones Precancerosas/patologíaRESUMEN
BACKGROUND: Altered microbiome composition and aberrant promoter hypermethylation of tumor suppressor genes (TSGs) are two important hallmarks of colorectal cancer (CRC). Here we performed concurrent 16S rRNA gene sequencing and methyl-CpG binding domain-based capture sequencing in 33 tissue biopsies (5 normal colonic mucosa tissues, 4 pairs of adenoma and adenoma-adjacent tissues, and 10 pairs of CRC and CRC-adjacent tissues) to identify significant associations between TSG promoter hypermethylation and CRC-associated bacteria, followed by functional validation of the methylation-associated bacteria. RESULTS: Fusobacterium nucleatum and Hungatella hathewayi were identified as the top two methylation-regulating bacteria. Targeted analysis on bona fide TSGs revealed that H. hathewayi and Streptococcus spp. significantly correlated with CDX2 and MLH1 promoter hypermethylation, respectively. Mechanistic validation with cell-line and animal models revealed that F. nucleatum and H. hathewayi upregulated DNA methyltransferase. H. hathewayi inoculation also promoted colonic epithelial cell proliferation in germ-free and conventional mice. CONCLUSION: Our integrative analysis revealed previously unknown epigenetic regulation of TSGs in host cells through inducing DNA methyltransferase by F. nucleatum and H. hathewayi, and established the latter as CRC-promoting bacteria. Video abstract.
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Clostridiaceae/patogenicidad , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Metilación de ADN , Células Epiteliales/metabolismo , Fusobacterium nucleatum/patogenicidad , Genes Supresores de Tumor , Regiones Promotoras Genéticas/genética , Anciano , Animales , Epigénesis Genética , Epigenoma , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , ARN Ribosómico 16S/genéticaRESUMEN
Clostridioides difficile infection (CDI) is a common cause of nosocomial diarrhea and can sometimes lead to pseudo-membranous colitis and toxic megacolon. We previously reported that the PCR ribotype 002 was a common C. difficile ribotype in Hong Kong that was associated with increased mortality. In this study, we assessed in vitro bacteriological characteristics and in vivo virulence of ribotype 002 compared to other common ribotypes, including ribotypes 012, 014 and 046. We observed significantly higher toxin A (p < 0.05) and toxin B (p < 0.05) production, sporulation (p < 0.001) and germination rates (p < 0.0001) in ribotype 002 than other common ribotypes. In a murine model of C. difficile infection, ribotype 002 caused significantly more weight loss (p < 0.001) and histological damage (p < 0.001) than other common ribotypes. These findings may have contributed to the higher prevalence and mortality observed, and provided mechanistic insights that can help public surveillance and develop novel therapeutics to combat against this infection.
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Clostridiales/patogenicidad , Infecciones por Bacterias Grampositivas/microbiología , Animales , Hong Kong , Masculino , Ratones Endogámicos C57BL , Ribotipificación , VirulenciaRESUMEN
A rapid, direct, and low-cost method for detecting bacterial toxins associated with common gastrointestinal diseases remains a great challenge despite numerous studies and clinical assays. Motion-based detection through tracking the emerging micro- and nanorobots has shown great potential in chemo- and biosensing due to accelerated "chemistry on the move". Here, we described the use of fluorescent magnetic spore-based microrobots (FMSMs) as a highly efficient mobile sensing platform for the detection of toxins secreted by Clostridium difficile (C. diff) that were present in patients' stool. These microrobots were synthesized rapidly and inexpensively by the direct deposition of magnetic nanoparticles and the subsequent encapsulation of sensing probes on the porous natural spores. Because of the cooperation effect of natural spore, magnetic Fe3O4 nanoparticles, and functionalized carbon nanodots, selective fluorescence detection of the prepared FMSMs is demonstrated in C. diff bacterial supernatant and even in actual clinical stool samples from infectious patients within tens of minutes, suggesting rapid response and good selectivity and sensitivity of FMSMs toward C. diff toxins.
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Proteínas Bacterianas/análisis , Toxinas Bacterianas/análisis , Clostridioides difficile/fisiología , Infecciones por Clostridium/diagnóstico , Nanopartículas de Magnetita/química , Nanomedicina/métodos , Tecnología de Sensores Remotos/métodos , Esporas Bacterianas , Carbono/química , Infecciones por Clostridium/microbiología , Heces/química , Heces/microbiología , Óxido Ferrosoférrico/química , Fluorescencia , Colorantes Fluorescentes/química , Humanos , Sensibilidad y EspecificidadRESUMEN
The involvement of microorganisms in cancer has been increasing recognized. Collectively, microorganisms have been estimated to account for â¼20% of all cancers worldwide. Recent advances in metagenomics and bioinformatics have provided new insights on the microbial ecology in different tumors, pinpointing the roles of microorganisms in cancer formation, development and response to treatments. Furthermore, studies have emphasized the importance of host-microbial and inter-microbial interactions in the cancer microbiota. These studies have not only revolutionized our understanding of cancer biology, but also opened up new opportunities for cancer prevention, diagnosis, prognostication and treatment. This review article aims to summarize the microbiota in various cancers and their treatments, and explore clinical applications for such relevance.
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Microbioma Gastrointestinal/genética , Metagenómica , Neoplasias/genética , Biología Computacional , Humanos , Neoplasias/diagnóstico , Neoplasias/microbiología , Neoplasias/terapiaRESUMEN
Leinamycin (LNM) is a potent antitumor antibiotic produced by Streptomyces atroolivaceus S-140. Both in vivo and in vitro characterization of the LNM biosynthetic machinery have established the formation of the 18-membered macrolactam backbone and the C-3 alkyl branch; the nascent product, LNM E1, of the hybrid nonribosomal peptide synthetase (NRPS)-acyltransferase (AT)-less type I polyketide synthase (PKS); and the generation of the thiol moiety at C-3 of LNM E1. However, the tailoring steps converting LNM E1 to LNM are still unknown. Based on gene inactivation and chemical investigation of three mutant strains, we investigated the tailoring steps catalyzed by two cytochromes P450 (P450s), LnmA and LnmZ, in LNM biosynthesis. Our studies revealed that (i) LnmA and LnmZ regio- and stereoselectively hydroxylate the C-8 and C-4' positions, respectively, on the scaffold of LNM; (ii) both LnmA and LnmZ exhibit substrate promiscuity, resulting in multiple LNM analogs from several shunt pathways; and (iii) the C-8 and C-4' hydroxyl groups play important roles in the cytotoxicity of LNM analogs against different cancer cell lines, shedding light on the structure-activity relationships of the LNM scaffold and the LNM-type natural products in general. These studies set the stage for future biosynthetic pathway engineering and combinatorial biosynthesis of the LNM family of natural products for structure diversity and drug discovery.
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Antibióticos Antineoplásicos/biosíntesis , Sistema Enzimático del Citocromo P-450/metabolismo , Lactamas Macrocíclicas/metabolismo , Lactamas/metabolismo , Macrólidos/metabolismo , Tiazoles/metabolismo , Tionas/metabolismo , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/toxicidad , Vías Biosintéticas , Línea Celular Tumoral , Sistema Enzimático del Citocromo P-450/genética , Escherichia coli/genética , Silenciador del Gen , Humanos , Hidroxilación , Lactamas/química , Lactamas/toxicidad , Lactamas Macrocíclicas/química , Lactamas Macrocíclicas/toxicidad , Macrólidos/química , Macrólidos/toxicidad , Estructura Molecular , Familia de Multigenes , Estereoisomerismo , Streptomyces/genética , Relación Estructura-Actividad , Tiazoles/química , Tiazoles/toxicidad , Tionas/química , Tionas/toxicidadRESUMEN
RATIONALE: Dermatomyositis is an idiopathic inflammatory myopathy with specific cutaneous manifestations, which is closely associated with malignancy. However, the exact mechanism remains elusive. Even less is known about dermatomyositis with hepatocellular carcinoma (HCC). PATIENT CONCERNS: We reported a case of dermatomyositis with hepatitis B virus (HBV) infection. He incidentally found his lower limbs little weakness accompanied with his wrist erythema. He was found HBsAg positive for forty years with slightly positive of α-fetal protein (AFP). DIAGNOSES: A dermapathology from his hand-wrist lesions demonstrated a scattered inflammatory infiltrate around the capillaries of the dermis. Abdominal enhanced computer tomography (CT) revealed infiltrative HCC affecting the whole liver, accompanied by liver metastasis and liver cirrhosis. Liver tumor needle biopsy pathology showed HCC with moderate differentiation. The left supraclavicular lymph node needle biopsy pathology confirmed metastasic HCC. INTERVENTIONS: Prednisolone was gradually withdrawn with the introduction of Entecavir 0.5âmg daily. Radiofrequency ablation therapy for liver tumor was performed once in order to decrease the tumor load. OUTCOMES: His muscle power improved to grade 4+/5 in the lower limb one month after anti-HBV treatment. However, this patient died finally from liver failure due to the development of liver tumor. LESSONS: In the coming clinic work, we must pay more attention to the extrahepatic disorder induced by HBV. On treating experience, glucocorticoid administration is often contraindicated for HBV infected patients because of its potential promotion of HBV replication. Thus, it is necessary to administrate high-effective anti-HBV drug prior to glucocorticoid treatment in order to prevent liver failure.
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Carcinoma Hepatocelular/complicaciones , Dermatomiositis/etiología , Virus de la Hepatitis B/efectos de los fármacos , Hepatitis B Crónica/complicaciones , Hepatitis B/complicaciones , Prednisolona/efectos adversos , Antivirales/uso terapéutico , Carcinoma Hepatocelular/diagnóstico por imagen , Carcinoma Hepatocelular/patología , Ablación por Catéter/métodos , Dermatomiositis/diagnóstico , Dermatomiositis/fisiopatología , Electromiografía , Resultado Fatal , Glucocorticoides/efectos adversos , Guanina/administración & dosificación , Guanina/análogos & derivados , Guanina/uso terapéutico , Humanos , Hígado/diagnóstico por imagen , Neoplasias Hepáticas , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos X/métodos , alfa-Fetoproteínas/metabolismoRESUMEN
BACKGROUND & AIMS: Colorectal cancer (CRC) development has been associated with increased proportions of Bacteroides fragilis and certain Streptococcus, Fusobacterium, and Peptostreptococcus species in the intestinal microbiota. We investigated associations between bacteremia from specific intestinal microbes and occurrence of CRC. METHODS: We performed a retrospective study after collecting data on 13,096 adult patients (exposed group) in Hong Kong hospitalized with bacteremia (identified by blood culture test) without a previous diagnosis of cancer from January 1, 2006 through December 31, 2015. We collected data on intestinal microbes previously associated with CRC (genera Bacteroides, Clostridium, Filifactor, Fusobacterium, Gemella, Granulicatella, Parvimonas, Peptostreptococcus, Prevotella, Solobacterium, and Streptococcus). Clinical information, including patient demographics, comorbid medical conditions, date of bacteremia, and bacterial species identified, were collected. The incidence of biopsy-proved CRC was compared between the exposed and unexposed (patients without bacteremia matched for age, sex, and comorbidities) groups. RESULTS: The risk of CRC was increased in patients with bacteremia from B fragilis (hazard ratio [HR] = 3.85, 95% CI = 2.62-5.64, P = 5.5 × 10-12) or Streptococcus gallolyticus (HR = 5.73, 95% CI = 2.18-15.1, P = 4.1 × 10-4) compared with the unexposed group. In addition, the risk of CRC was increased in patients with bacteremia from Fusobacterium nucleatum (HR = 6.89, 95% CI = 1.70-27.9, P = .007), Peptostreptococcus species (HR = 3.06, 95% CI = 1.47-6.35, P = .003), Clostridium septicum (HR = 17.1, 95% CI = 1.82-160, P = .013), Clostridium perfringens (HR = 2.29, 95% CI = 1.16-4.52, P = .017), or Gemella morbillorum (HR = 15.2, 95% CI = 1.54-150, P = .020). We observed no increased risk in patients with bacteremia caused by microbes not previously associated with colorectal neoplasms. CONCLUSIONS: In a retrospective analysis of patients hospitalized for bacteremia, we associated later diagnosis of CRC with B fragilis and S gallolyticus and other intestinal microbes. These bacteria might have entered the bloodstream from intestinal dysbiosis and perturbed barrier function. These findings support a model in which specific members of the intestinal microbiota promote colorectal carcinogenesis. Clinicians should evaluate patients with bacteremia from these species for neoplastic lesions in the colorectum.
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Bacteriemia/microbiología , Colon/microbiología , Neoplasias Colorrectales/sangre , Disbiosis/sangre , Microbioma Gastrointestinal , Adulto , Anciano , Anciano de 80 o más Años , Bacteroides fragilis/aislamiento & purificación , Bacteroides fragilis/patogenicidad , Biopsia , Carcinogénesis , Colon/patología , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/microbiología , Disbiosis/diagnóstico , Disbiosis/epidemiología , Disbiosis/microbiología , Femenino , Hong Kong/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Streptococcus gallolyticus/aislamiento & purificación , Streptococcus gallolyticus/patogenicidadRESUMEN
Toxin B (TcdB) is a major pathogenic factor of Clostridum difficile. However, the mechanism by which TcdB exerts its cytotoxic action in host cells is still not completely known. Herein, we report for the first time that TcdB induced autophagic cell death in cultured human colonocytes. The induction of autophagy was demonstrated by the increased levels of LC3-II, formation of LC3+ autophagosomes, accumulation of acidic vesicular organelles and reduced levels of the autophagic substrate p62/SQSTM1. TcdB-induced autophagy was also accompanied by the repression of phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) complex 1 activity. Functionally, pharmacological inhibition of autophagy by wortmannin or chloroquine or knockdown of autophagy-related genes Beclin 1, Atg5 and Atg7 attenuated TcdB-induced cell death in colonocytes. Genetic ablation of Atg5, a gene required for autophagosome formation, also mitigated the cytotoxic effect of TcdB. In conclusion, our study demonstrated that autophagy serves as a pro-death mechanism mediating the cytotoxic action of TcdB in colonocytes. This discovery suggested that blockade of autophagy might be a novel therapeutic strategy for C. difficile infection.
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Autofagia/genética , Proteínas Bacterianas/genética , Toxinas Bacterianas/genética , Clostridioides difficile/genética , Infecciones por Clostridium/terapia , Apoptosis/efectos de los fármacos , Autofagosomas/efectos de los fármacos , Autofagosomas/metabolismo , Autofagosomas/microbiología , Proteína 5 Relacionada con la Autofagia , Proteína 7 Relacionada con la Autofagia , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/metabolismo , Beclina-1/genética , Clostridioides difficile/patogenicidad , Infecciones por Clostridium/genética , Infecciones por Clostridium/microbiología , Colon/citología , Colon/microbiología , Humanos , Fosfatidilinositol 3-Quinasas/genética , Fosforilación , Proteína Sequestosoma-1/genética , Serina-Treonina Quinasas TOR/genéticaRESUMEN
Incidence of Clostridium difficile infection (CDI) is rapidly increasing and it poses a major health burden globally. However, data regarding the epidemiology of CDI in Asia are limited. We aimed to characterize the antimicrobial susceptibility patterns of common ribotypes of toxigenic C. difficile in Hong Kong. Fifty-three PCR ribotypes were identified among 284 toxigenic C. difficile clinical isolates. The five most prevalent ribotypes were 002 (13%), 017 (12%), 014 (10%), 012 (9.2%), and 020 (9.5%). All tested C. difficile strains remained susceptible to metronidazole, vancomycin, meropenem and piperacillin/tazobactam, but highly resistant to cephalosporins. Of the fluoroquinolones, highest resistance to ciprofloxacin was observed (99%), followed by levofloxacin (43%) and moxifloxacin (23%). The two newly emerged PCR ribotypes, 017 and 002, demonstrated high levels of co-resistance towards clindamycin, tetracycline, erythromycin and moxifloxacin. PCR ribotypes 017 and 002 with multi-drug resistance are rapidly emerging and continuous surveillance is important to monitor the epidemiology of C. difficile to prevent outbreaks of CDI.
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Antibacterianos/farmacología , Clostridioides difficile/clasificación , Clostridioides difficile/efectos de los fármacos , Farmacorresistencia Bacteriana , Ribotipificación , Clostridioides difficile/genética , Hong Kong , Reacción en Cadena de la PolimerasaRESUMEN
Cross-sectional studies suggest an increasing trend in incidence and relatively low recurrence rates of Clostridium difficile infections in Asia than in Europe and North America. The temporal trend of C. difficile infection in Asia is not completely understood. We conducted a territory-wide population-based observational study to investigate the burden and clinical outcomes in Hong Kong, China, over a 9-year period. A total of 15,753 cases were identified, including 14,402 (91.4%) healthcare-associated cases and 817 (5.1%) community-associated cases. After adjustment for diagnostic test, we found that incidence increased from 15.41 cases/100,000 persons in 2006 to 36.31 cases/100,000 persons in 2014, an annual increase of 26%. This increase was associated with elderly patients, for whom incidence increased 3-fold over the period. Recurrence at 60 days increased from 5.7% in 2006 to 9.1% in 2014 (p<0.001). Our data suggest the need for further surveillance, especially in Asia, which contains ≈60% of the world's population.
Asunto(s)
Clostridioides difficile/aislamiento & purificación , Infecciones por Clostridium/epidemiología , Infección Hospitalaria/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/mortalidad , Infecciones Comunitarias Adquiridas , Infección Hospitalaria/microbiología , Infección Hospitalaria/mortalidad , Estudios Transversales , Monitoreo Epidemiológico , Femenino , Hong Kong/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Recurrencia , Análisis de SupervivenciaRESUMEN
BACKGROUND & AIMS: Altered gut microbiota is implicated in development of colorectal cancer (CRC). Some intestinal bacteria have been reported to potentiate intestinal carcinogenesis by producing genotoxins, altering the immune response and intestinal microenvironment, and activating oncogenic signaling pathways. We investigated whether stool from patients with CRC could directly induce colorectal carcinogenesis in mice. METHODS: We obtained stored stool samples from participants in a metagenome study performed in Hong Kong. Conventional (male C57BL/6) mice were given azoxymethane to induce colon neoplasia after receiving a course of antibiotics in drinking water. Mice were gavaged twice weekly with stool from 5 patients with CRC or 5 healthy individuals (controls) for 5 weeks. Germ-free C57BL/6 mice were gavaged once with stool from 5 patients with CRC or 5 controls. We collected intestinal tissues from mice and performed histology, immunohistochemistry, expression microarray, quantitative polymerase chain reaction, immunoblot, and flow cytometry analyses. We performed 16S ribosomal RNA gene sequencing analysis of feces from mice. RESULTS: Significantly higher proportions of conventional mice fed with stool from individuals with CRC than control stool developed high-grade dysplasia (P < .05) and macroscopic polyps (P < .01). We observed a higher proportion of proliferating (Ki-67-positive) cells in colons of germ-free mice fed with stool from patients with CRC vs those fed with stool from controls (P < .05). Feces from germ-free and conventional mice fed with stool from patients with CRC vs controls contained different microbial compositions, with lower richness in mice fed with stool from patients with CRC. Intestines collected from conventional and germ-free mice fed with stool from patients with CRC had increased expression of cytokines that modulate inflammation, including C-X-C motif chemokine receptor 1, C-X-C motif chemokine receptor 2, interleukin 17A (IL17A), IL22, and IL23A. Intestines from conventional and germ-free mice fed with stool from patients with CRC contained higher proportions of T-helper 1 (Th1) cells (2.25% vs 0.44%) and Th17 cells (2.08% vs 0.31%) (P < .05 for each) than mice fed with stool from controls. Real-time polymerase chain reaction arrays revealed up-regulation of genes involved in cell proliferation, stemness, apoptosis, angiogenesis, invasiveness, and metastasis in mice fed with stool from patients with CRC. CONCLUSIONS: We fed stool samples from patients with CRC and heathy individuals to germ-free mice and conventional mice with azoxymethane. We found stool from patients with CRC to increase the numbers of polyps, levels of intestinal dysplasia and proliferation, markers of inflammation, and proportions of Th1 and Th17 cells in colon, compared with stool from individuals without CRC. This study provides evidence that the fecal microbiota from patients with CRC can promote tumorigenesis in germ-free mice and mice given a carcinogen.
Asunto(s)
Transformación Celular Neoplásica , Colon/microbiología , Pólipos del Colon/microbiología , Neoplasias Colorrectales/microbiología , Heces/microbiología , Microbioma Gastrointestinal , Animales , Azoximetano , Estudios de Casos y Controles , Proliferación Celular , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Colon/metabolismo , Colon/patología , Pólipos del Colon/inducido químicamente , Pólipos del Colon/metabolismo , Pólipos del Colon/patología , Neoplasias Colorrectales/inducido químicamente , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Modelos Animales de Enfermedad , Regulación Neoplásica de la Expresión Génica , Vida Libre de Gérmenes , Interacciones Huésped-Patógeno , Humanos , Mediadores de Inflamación/metabolismo , Antígeno Ki-67/metabolismo , Linfocitos Infiltrantes de Tumor/metabolismo , Linfocitos Infiltrantes de Tumor/microbiología , Masculino , Ratones Endogámicos C57BL , Células TH1/metabolismo , Células TH1/microbiología , Células Th17/metabolismo , Células Th17/microbiologíaRESUMEN
Focal copy number gains or losses are important genomic hallmarks of cancer. The genomic distribution of oncogenes and tumor-suppressor genes (TSG) in relation to focal copy number aberrations is unclear. Our analysis revealed that the mean distance of TSGs from oncogenes was significantly shorter than that of noncancer genes, suggesting that oncogenes and TSGs tend to be in close physical proximity in the human genome. Such relationship was conserved in mouse and drosophila. Pan-cancer analysis using data from The Cancer Genome Atlas indicated that oncogenes without a nearby TSG are more prone to amplification. In conclusion, our study provides evidence for the nonrandom distribution of oncogenes and TSGs across different species. Our data also support that the existence of a neighboring TSG can suppress amplification of an oncogene, shedding new light on a previously unappreciated protective mechanism of TSGs.