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Where Cancer and Bacteria Meet
Published in Ananda M. Chakrabarty, Arsénio M. Fialho, Microbial Infections and Cancer Therapy, 2019
Alexandra Merlos, Ricardo Perez-Tomás, José López-López, Miguel Viñas
Anaerobic gram-negative bacteria have also been implicated in several forms of cancer. One of the best studied species is Fusobacterium nucleatum, representative of the genus Fusobacterium. This spindle-shaped strict anaerobe is commonly found both in the oral cavity and in the gut. F. nucleatum induces permanent chronic inflammation in the colon and has thus been associated with colorectal cancer. However, the mechanism is still unclear. Rubinstein et al. [15] showed that F. nucleatum adheres to and invades tissues, which activates inflammatory responses and stimulates the growth of colorectal cells. The underlying mechanism involves the interaction of colonic cells with the bacterial adhesin FadA, which binds to E-cadherin. The same authors showed 100 times higher fadA gene levels in the colon tissue from patients with adenomas and adenocarcinomas than in healthy individuals, thus identifying FadA as a potential diagnostic and therapeutic target for colorectal cancer.
Prevalence of Bacterial Infections in Respiratory Tract
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Boopathi Balasubramaniam, U. Prithika, K. Balamurugan
Be it in the mucosal surface or blood, the bacterial pathogenesis involves the bacterial adherence to cell surfaces of host system followed by cellular invasion (Figure 3.4). The successful invasion of the bacterial cells was due to adherence to the two receptors present on the surface of various cell types (e.g., the platelet activating factor receptor (PAFr) and 37/67 kDa laminin receptor [LR]). Orihuela et al. (2009) reported that the bacterial adhesin protein CbpA primarily bound to endothelial LR. CbpA surface-exposed loop mediated binding to the polymeric immunoglobulin receptor was accountable for the Pneumococcus translocation across the nasopharyngeal epithelium (Zhang et al. 2000). It was also notable that CbpA binding mediated adherence of the bacterial cells to LR but not invasion. Significantly, LR also acted as a target for Neisseria meningitidis and H. influenzae pathogenesis. The antibody of CbpA cross-reacted and blocked the adherence of these meningeal pathogens, representing a shared binding mechanism. These results suggest that a series of pathogens target LR as a major step in the host-pathogen interactions.
Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7
Published in Gut Microbes, 2022
Hongmin Sun, Min Wang, Yutao Liu, Pan Wu, Ting Yao, Wen Yang, Qian Yang, Jun Yan, Bin Yang
The gastrointestinal tract is lined by a continuously secreted mucus layer formed mainly by high-molecular mass (200–2000 kDa) oligomeric mucin glycoproteins.24 Mucins act as receptors for bacterial adhesin proteins and provide protection against the adherence of infectious pathogens by steric hindrance or through specific bacterial binding domains.60,61 A whole genome-scale transcriptome analysis revealed that 732 candidate genes were differentially expressed in EHEC O157:H7 in the presence of 0.5% porcine stomach mucin.24 Of particular interest, eight genes associated with flagellar biosynthesis (including flgA, flgB, flgF, flgG, flgH, flgJ, fliP, and yaiU) were all downregulated in the presence of mucin. Furthermore, qRT-PCR analyses showed that the expression of six genes in the flg operon (i.e., flgABFGH and flgJ) was downregulated two- to five-folds in the presence of mucin, which further verified the transcriptome analysis results. Consistently, the bacterial motility was also significantly reduced when EHEC O157:H7 was grown on 0.3% tryptone agar plates containing mucin. Therefore, mucin may act as an intestinal environmental signal that negatively regulates EHEC O157:H7 motility through the transcriptional repression of the flg gene that encodes the components of the flagellar basal body.24
Yersinia pseudotuberculosis YopE prevents uptake by M cells and instigates M cell extrusion in human ileal enteroid-derived monolayers
Published in Gut Microbes, 2021
Alyssa C. Fasciano, Gaya S. Dasanayake, Mary K. Estes, Nicholas C. Zachos, David T. Breault, Ralph R. Isberg, Shumin Tan, Joan Mecsas
Many diverse bacterial and viral pathogens, including enteric Yersinia spp., exploit specialized epithelial microfold (M) cells that reside within the follicular associated epithelium (FAE) above Peyer’s patches (PP) to gain access to deeper tissues.1–3 M cells play a major role in immunosurveillance by taking up and delivering luminal contents to PP and have distinct morphology including apical polarization of β1 integrin and the lack of tightly packed apical microvilli present on neighboring enterocytes.1,4–6 The enteropathogenic bacteria, Yersinia pseudotuberculosis (Yptb) and Y. enterocolitica, are primarily transmitted via ingestion of contaminated food by the fecal-oral route and are psychrotrophs that can grow at temperatures below 4°C.7 Thus, outbreaks have been associated with food stored in the cold such as milk products and vegetables.8–12 After ingestion, Yptb primarily targets to the terminal ileum and gain access to underlying lymph tissues to cause acute intestinal illness and mesenteric lymphadenitis and in rare cases can spread systemically.13 In murine intestinal ligated loop infection models, Yptb has been shown to bind to β1 integrins on M cells using the bacterial adhesin protein invasin.2,14 After breaching the intestinal layer, Yersinia establish infection in PP and form extracellular microcolonies derived from a clonal bacterium.15–18
The expanding field of platelet–bacterial interconnections
Published in Platelets, 2015
Unlike physiological platelet agonists that confer specificity for a platelet receptor, bacteria can interact with platelets using a number of different mechanisms. A direct interaction (Figure 1A) occurs when a bacterial adhesin binds directly to a platelet receptor or other surface expressed component on the platelet [13, 14]. An indirect interaction (Figure 1B) occurs when a bacterial adhesin binds to a plasma protein or other soluble elements of the immune system such as immunoglobulins and complement proteins which bridge the bacteria to a specific receptor or other expressed component on the platelet surface [15–17]. Finally, certain bacteria can secrete toxins or other bacterial products that bind to the platelet-causing activation independently of bacterial attachment [18, 19].