Helicobacter pylori BabA–SabA Key Roles in the Adherence Phase: The Synergic Mechanism for Successful Colonization and Disease Development

Helicobacter pylori is a pathogenic microorganism that successfully inhabits the human stomach, colonizing it by producing several virulence factors responsible for preventing host self-defense mechanisms. The adherence mechanism to gastric mucosal tissue is one of the most important processes for effective colonization in the stomach. The blood group antigen-binding adhesion (BabA) and sialic acid-binding adherence (SabA) are two H. pylori outer membrane proteins able to interact with antigens in the gastroduodenal tract. H. pylori possesses several mechanisms to control the regulation of both BabA and SabA in either the transcriptional or translational level. BabA is believed to be the most important protein in the early infection phase due to its ability to interact with various Lewis antigens, whereas SabA interaction with sialylated Lewis antigens may prove important for the adherence process in the inflamed gastric mucosal tissue in the ongoing-infection phase. The adherence mechanisms of BabA and SabA allow H. pylori to anchor in the gastric mucosa and begin the colonization process.

A Novel Type of Wall-Climbing Robot with a Gear Transmission System Arm and Adhere Mechanism Inspired by Cicada and Gecko

To support the inspections of different contact walls (rough and smooth), a novel type of wall-climbing robot was proposed. Its design embodied a new gear transmission system arm and an adherence mechanism inspired by cicadas and geckos. The actuating structure consisted of a five-bar link and a gear transmission for the arm stretching, which was driven by the servos. The linkers and gears formed the palm of this robot for climbing on a line. Moreover, the robot’s adherence method for the rough surfaces used bionic spine materials inspired by the cicada. For smooth surface, a bionic adhesion material was proposed inspired by the gecko. To assess the adherence mechanism of the cicada and gecko, the electron microscope images of the palm of the cicada and gecko were obtained by an electron microscope. The 3D printing technology and photolithography technology were utilized to manufacture the robot’s structures. The adherence force experiments demonstrated the bionic spines and bionic materials achieved good climbing on cloth, stones, and glass surfaces. Furthermore, a new gait for the robot was designed to ensure its stability. The dynamic characteristics of the robot’s gear transmission were obtained.

TheEscherichia coliO157:H7 Carbon Starvation-Inducible Lipoprotein Slp Contributes to Initial AdherenceIn Vitrovia the Human Polymeric Immunoglobulin Receptor

Escherichia coliO157:H7 is the most well-studied serotype of enterohemorrhagicE. coli(EHEC) class ofE. coliintestinal pathogens, and is responsible for many outbreaks of serious food-borne illness worldwide each year. Adherence mechanisms are a critical component of its pathogenesis, persistence in natural reservoirs, and environmental contamination.E. coliO157:H7 has a highly effective virulence operon, the Locus of Enterocyte Effacement (LEE), and its encoded intimate adherence mechanism is well characterized. However, factors involved in the preceding initial attachment are not well understood. In this study, we propose a mechanism of initial adherence used byE. coliO157:H7in vitro. We describe a bacterial protein not previously reported to be involved in adherence, Slp, and its interactions with the human host protein polymeric immunoglobulin receptor (pIgR). The human pIgR has previously been shown to act as an adherence receptor for some mucosal pathogens, and is highly expressed in the intestine. Following observation of significant colocalization betweenE. coliO157:H7 and pIgR location on Caco-2 cells, a co-immunoprecipitation (Co-IP) assay using a human recombinant Fc-tagged pIgR protein led to the identification of this protein. Disruption of Slp expression inE. coliO157:H7, through deletion of its encoding geneslp, produced a significant adherence deficiency to Caco-2 cells at early time points associated with initial adherence. Plasmid complementation ofslpfully restored the wild-type phenotype. Furthermore, immunofluorescence microscopy revealed evidence that this interaction is specific to the pathogenic strains ofE. colitested, and not the nonpathogenic strain E. coli K12. Additionally, deletion ofslpresulted in the absence of the corresponding protein band in further Co-IP assays, while the plasmid-encodedslpcomplementation of the deletion mutant strain restored the wild-type pattern. These data support the proposal that Slp directly contributes to initial adherence, with the pIgR protein as its proposed receptor.Author summaryEscherichia coliO157:H7 and other enterohemorrhagicE. coli(EHEC) are responsible for tens of thousands of cases of food-borne illness in the United States each year.E. coliO157:H7 has a particularly effective intimate adherence mechanism. However, the mechanisms of initial adherence, which facilitate attachment and virulence prior to the engagement of intimate adherence, are not well understood. In this study, we describe an initial adherence interaction between theE. coliO157:H7 Slp and the human polymeric immunoglobulin receptor (pIgR) expressed by the human colonic epithelial cell line Caco-2. The relationship was first demonstrated as a significant colocalization between the locations ofE. coliO157:H7 bacterial cells and pIgR protein using immunofluorescence microscopy. TheE. coliO157:H7 Slp protein was identified, and disruption of theslpgene resulted in a severe adherence deficiency to Caco-2 cells during initial adherence. This effect was reversed upon complementation of the Δslpstrain with a plasmid-encodedslpgene, and the constitutive over-expression ofslpresulted in hyper-adherence exceeding that of the wild-typeE. coliO157:H7. These data support the proposition that Slp directly contributes to initial adherence, with the pIgR protein as its proposed receptor.

Formyl Met-Leu-Phe-Stimulated FPR1 Phosphorylation in Plate-Adherent Human Neutrophils: Enhanced Proteolysis but Lack of Inhibition by Platelet-Activating Factor

N-formyl-Met-Leu-Phe (fMLF) is a model PAMP/DAMP driving human PMN to sites of injury/infection utilizing the GPCR, FPR1. We examined a microtiter plate format for measurement of FPR1 phosphorylation in adherent PMN at high densities and found that a new phosphosensitive FPR1 fragment, 25K-FPR1, accumulates in SDS-PAGE extracts. 25K-FPR1 is fully inhibited by diisopropylfluorophosphate PMN pretreatment but is not physiologic, as its formation failed to be significantly perturbed by ATP depletion, time and temperature of adherence, or adherence mechanism. 25K-FPR1 was minimized by extracting fMLF-exposed PMN in lithium dodecylsulfate at 4°C prior to reduction/alkylation. After exposure of adherent PMN to a 5 log range of PAF before or after fMLF, unlike in suspension PMN, no inhibition of fMLF-induced FPR1 phosphorylation was observed. However, PAF induced the release of 40% of PMN lactate dehydrogenase, implying significant cell lysis. We infer that PAF-induced inhibition of fMLF-dependent FPR1 phosphorylation observed in suspension PMN does not occur in the unlysed adherent PMN. We speculate that although the conditions of the assay may induce PAF-stimulated necrosis, the cell densities on the plates may approach levels observed in inflamed tissues and provide for an explanation of PAF’s divergent effects on FPR1 phosphorylation as well as PMN function.

The Adherence Mechanism of Superalloy Honing Oilstone

On the foundation of researching adhesion mechanism of superalloy honing stone, theoretical analysis and mathematical modeling of parameters were made that affecting the wear particle adhesion rate of superalloy honing stone, then inspect and verify the relation between the adhesion rate and processing parameters through the experiment. Draw the conclusion that when the honing pressure increases or the speed of work piece decreases, the adhesion rate αa will increase.

Adherence Evaluation in Tile-Mortar Interface

This article deals with some of preliminary tests to study the adherence mechanism of lime mortars to late XIXth Century tiles. The bond between them is mainly physical. A water absorption by capillary test and a suction test were performed to study the parameters of mortar penetration in tiles porosity. The old tiles seem to have a higher porosity than new ones. Some of the new specimens can be used to simulate the old tiles in future tests without applying partially destructive tests to historical objects.

BgaA acts as an adhesin to mediate attachment of some pneumococcal strains to human epithelial cells

Streptococcus pneumoniae colonization of the respiratory tract is an essential precursor for pneumococcal disease. To colonize efficiently, bacteria must adhere to the epithelial-cell surface. S. pneumoniae possesses surface-associated exoglycosidases that are capable of sequentially deglycosylating human glycans. Two exoglycosidases, neuraminidase (NanA) and β-galactosidase (BgaA), have previously been shown to contribute to S. pneumoniae adherence to human epithelial cells, as deletion of either of these genes results in reduced adherence. It has been suggested that these enzymes may modulate adherence by cleaving sugars to reveal a receptor on host cells. Pretreatment of epithelial cells with exogenous neuraminidase restores the adherence of a nanA mutant, whereas pretreatment with β-galactosidase does not restore the adherence of a bgaA mutant. These data suggest that BgaA may not function to reveal a receptor, and implicate an alternative role for BgaA in adherence. Here we demonstrate that β-galactosidase activity is not required for BgaA-mediated adherence. Addition of recombinant BgaA (rBgaA) to adherence assays and pretreatment of epithelial cells with rBgaA both significantly reduced the level of adherence of the parental strain, but not the BgaA mutant. One possible explanation of these data is that BgaA is acting as an adhesin and that rBgaA is binding to the receptor, preventing bacterial binding. A bead-binding assay demonstrated that BgaA can bind directly to human epithelial cells, supporting the hypothesis that BgaA is an adhesin. Preliminary characterization of the epithelial-cell receptor suggests that it is a glycan in the context of a glycosphingolipid. To further establish the relevance of this adherence mechanism, we demonstrated that BgaA-mediated adherence contributed to adherence of a recent clinical isolate to primary human epithelial cells. Together, these data suggest a novel role for BgaA as an adhesin and suggest that this mechanism could contribute to adherence of at least some pneumococcal strains in vivo.

Role of flm Locus in MesophilicAeromonas Species Adherence

ABSTRACT The adherence mechanism of Aeromonas caviae Sch3N to HEp-2 cells was initially investigated through four mini-Tn5 mutants that showed a 10-fold decrease in adherence. These mutants lost motility, flagella, and their lipopolysaccharide (LPS) O antigen (O-Ag). Three genes,flmB-neuA-flmD, were found to be interrupted by the transposon insertions; additionally, two other genes, one lying upstream (flmA) and one downstream (neuB), were found to be clustered in the same operon. While the flmAand flmB genes were present in all mesophilicAeromonas spp. (A. hydrophila, A. caviae, A. veronii bv. veronii, andA. veronii bv. sobria) tested, this was not the case for the neuA-flmD-neuB genes. Construction and characterization of flmB insertion mutants in five other mesophilic Aeromonas strains revealed the loss of motility, flagella, and adherence but did not alter the LPS composition of these strains. Taking the above findings into consideration, we conclude (i) that flagella and possibly the LPS O-Ag are involved in the adherence of the mesophilic Aeromonas to human epithelial cells; (ii)flmA and flmB are genes widely distributed in the mesophilic Aeromonas and are involved in flagella assembly, and thus adherence; and (iii) in A. caviae Sch3N the flmA and flmB genes are found in a putative operon together with neuA, flmD, andneuB and are involved in LPS O-Ag biosynthesis and probably have a role in flagellum assembly.