Escherichia coli bind to urinary bladder epithelium through nonspecific sialic acid mediated adherence

Differential expression of glycans in the urothelial layers of horse urinary bladder

BACKGROUND

Urothelium is a multilayer epithelium covering the inner surface of the urinary bladder that acts as a blood-urine barrier and is involved in maintaining the wellbeing of the whole organism. Glycans serve in the maturation and differentiation of cells and thus play a key role in the morphology and function of the multilayered epithelium. The aim of the present study was to examine the glycoprotein pattern of the horse urinary bladder urothelium by lectin histochemistry.

METHODS

The study involved urinary bladders from four horse stallions. Tissue sections were stained with a panel of eleven lectins, in combination with saponification and sialidase digestion (Ks).

RESULTS

Basal cells displayed high-mannose N-glycans (Con A), α2,6-linked sialic acid (SNA), and O-linked sialoglycans with sialic acids linked to Galβl,3GalNAc (T antigen) (KsPNA) and terminal N-acetylgalactosamine (Tn antigen) (KsSBA). The young intermediate cells expressed terminal N-acetylglucosamine (GlcNAc) (GSA II), galactose (GSA I-B₄), T- and Tn antigens (PNA, SBA). The mature intermediate cells showed additional high-mannose N-glycans, O-linked sialoglycans (sialyl-T antigen, sialyl-Tn antigen), α2,6- and α2,3-linked sialic acid (MAL II), α1,2-linked fucose (UEA I), and GlcNAc (KsWGA). The latter residue marked the boundary with the overlying surface layer. Few Con A positive intermediate cells were seen to cross the entire urothelium thickness. The surface cells showed additional glycans such as T antigen and sialic acids linked to GalNAc binding DBA (KsDBA). Few surface cells contained α1,3-linked fucose (LTA), whereas some other cells displayed intraluminal secretion of mucin-type glycans terminating with GalNAcα1,3(LFucα1,2)Galβ1,3/4GlcNAcβ1 (DBA). The luminal surface expressed the most complex glycan pattern in the urothelium because only α1,3-linked fucose lacked among the demonstrated glycans.

CONCLUSIONS

This study showed that the glycan pattern becomes more complex from the basal to surface layer of the urothelium and that surface cells could modify the composition of urine via the secretion of glycoproteins.

Sialic Acid-Siglec Axis as Molecular Checkpoints Targeting of Immune System: Smart Players in Pathology and Conventional Therapy

The sialic acid-based molecular mimicry in pathogens and malignant cells is a regulatory mechanism that leads to cross-reactivity with host antigens resulting in suppression and tolerance in the immune system. The interplay between sialoglycans and immunoregulatory Siglec receptors promotes foreign antigens hiding and immunosurveillance impairment. Therefore, molecular targeting of immune checkpoints, including sialic acid-Siglec axis, is a promising new field of inflammatory disorders and cancer therapy. However, the conventional drugs used in regular management can interfere with glycome machinery and exert a divergent effect on immune controlling systems. Here, we focus on the known effects of standard therapies on the sialoglycan-Siglec checkpoint and their importance in diagnosis, prediction, and clinical outcomes.

Type 1 Fimbriae and Motility Play a Pivotal Role During Interactions of Salmonella typhimurium with Acanthamoeba castellanii (T4 Genotype)

Amoebic bacterial interactions are the most ancient form of host pathogen interactions. Here, we investigate the fate of Salmonella typhimurium and Acanthamoeba castellanii T4 genotype upon mutual interactions in a nutrition free environment. The role of type 1 fimbriae and motility of S. typhimurium during interactions with A. castellanii has also been investigated. Deletion of genes encoding the type 1 fimbriae subunit FimA, type 1 fimbriae tip protein FimH, chemotaxis regulatory proteins CheA and CheY and major flagella subunits FliC and FljB was performed through homologous recombination. In vitro association, invasion and survival assays of S. typhimurium wild-type and mutant strains were performed upon co-incubation of bacteria with A. castellanii trophozoites in a nutrition free environment. The deletion gene encoding type 1 fimbriae subunit FimA reduced, whereas the deletion of genes encoding flagella subunits FliC and FljB of flagella enhanced the association capability of S. typhimurium with A. castellanii. Invasion of A. castellanii by Salmonella was significantly reduced upon the loss of type 1 fimbriae subunit FimA and type 1 fimbriae tip protein FimH. Co-incubation of S. typhimurium with A. castellanii in phosphate buffered saline medium stimulated the growth of S. typhimurium wild-type and mutant strains. Viable A. castellanii trophozoites count became significantly reduced upon co-incubation with S. typhimurium within 48 h. Type 1 fimbriae play a pivotal role in the adherence of S. typhimurium to the A. castellanii cell surface. Subsequently, this interaction provides S. typhimurium an advantage in growth.

Long-term use of noble metal alloy coated urinary catheters reduces recurrent CAUTI and decreases proinflammatory markers

BACKGROUND

The objective of this study was to investigate a case of a permanently (suprapubic) catheterized woman with neurogenic bladder dysfunction. The patient had suffered from recurrent catheter-associated urinary tract infections (CAUTIs) since 2009, despite several prevention approaches and attempts. In 2013, the patient's catheter was substituted for the BIP Foley Catheter, coated with a noble metal alloy (NMA) of gold, silver, and palladium.

METHOD

This is a retrospective-prospective clinical case study covering 4 years history for the control catheters and up to 2.5 years for the anti-infective BIP Foley Catheter. CAUTI incidences, symptoms, antibiotics, catheter performance, and comfort were evaluated. Levels of proinflammatory cytokines were measured pre- and post-substitution to BIP Foley Catheter in urine of the case and of four other permanently catheterized patients. In addition, the levels of noble metals were assessed in urine of the case subject during use of the BIP Foley Catheter.

RESULTS

While using control catheters, the patient experienced symptomatic CAUTIs requiring antibiotics almost every month for 4 years. After 1 month with the BIP Foley Catheter, the symptoms disappeared, and the patient remained free of symptomatic CAUTIs and antibiotic treatment for the following 2.5 years, despite bacteriuria. The patient was satisfied with the comfort during insertion, use, and removal of the BIP Foley Catheter. Urinary levels of the proinflammatory cytokines interleukin (IL)-6, IL-8, and tumor necrosis factor alpha (TNFα) decreased towards normal levels post catheter type substitution. Traces of noble metals detected in a few urine samples were ⩽4% of the permitted daily exposure. The levels of the noble metals gold, silver, and palladium remaining on the BIP Foley Catheter after use were the same as for unused catheters.

CONCLUSION

Long-term use of a NMA-coated catheter was associated with cessation of frequent CAUTIs. The catheter was experienced as comfortable and inflammatory markers were reduced with time. The coating was stable, with no significant metal release into urine and is therefore safe for patient use.

Desialylation of Spermatozoa and Epithelial Cell Glycocalyx Is a Consequence of Bacterial Infection of the Epididymis

Urinary tract infections caused by uropathogenic Escherichia coli (UPEC) pathovars belong to the most frequent infections in humans. In men, pathogens can also spread to the genital tract via the continuous ductal system, eliciting bacterial prostatitis and/or epididymo-orchitis. Antibiotic treatment usually clears pathogens in acute epididymitis; however, the fertility of patients can be permanently impaired. Because a premature acrosome reaction was observed in an UPEC epididymitis mouse model, and sialidases on the sperm surface are considered to be activated via proteases of the acrosome, we aimed to investigate whether alterations of the sialome of epididymal spermatozoa and surrounding epithelial cells occur during UPEC infection. In UPEC-elicited acute epididymitis in mice, a substantial loss of N-acetylneuraminic acid residues was detected in epididymal spermatozoa and epithelial cells using combined laser microdissection/HPLC-ESI-MS analysis. In support, a substantial reduction of sialic acid residues bound to the surface of spermatozoa was documented in men with a recent history of E. coli-associated epididymitis. In vitro, such an UPEC induced N-acetylneuraminic acid release from human spermatozoa was effectively counteracted by a sialidase inhibitor. These findings strongly suggest a substantial remodeling of the glycocalyx of spermatozoa and epididymal epithelial cells by endogenous sialidases after a premature acrosome reaction during acute epididymitis.

Enterotoxigenic Escherichia coli CS21 pilus contributes to adhesion to intestinal cells and to pathogenesis under in vivo conditions

Colonization surface antigens (CSs) represent key virulence-associated factors of enterotoxigenic Escherichia coli (ETEC) strains. They are required for gut colonization, the first step of the diarrhoeal disease process induced by these bacteria. One of the most prevalent CSs is CS21, or longus, a type IV pili associated with bacterial self-aggregation, protection against environmental stresses, biofilm formation and adherence to epithelial cell lines. The objectives of this study were to assess the role of CS21 in adherence to primary intestinal epithelial cells and to determine if CS21 contributes to the pathogenesis of ETEC infection in vivo. We evaluated adherence of a CS21-expressing wild-type ETEC strain and an isogenic CS21-mutant strain to pig-derived intestinal cell lines. To determine the role of CS21 in pathogenesis we used the above ETEC strains in a neonatal mice challenge infection model to assess mortality. Quantitative adherence assays confirmed that ETEC adheres to primary intestinal epithelial cells lines in a CS21-dependent manner. In addition, the CS21-mediated ETEC adherence to cells was specific as purified LngA protein, the CS21 major subunit, competed for binding with the CS21-expressing ETEC while specific anti-LngA antibodies blocked adhesion to intestinal cells. Neonatal DBA/2 mice died after intra-stomach administration of CS21-expressing strains while lack of CS21 expression drastically reduced the virulence of the wild-type ETEC strain in this animal model. Collectively these results further support the role of CS21 during ETEC infection and add new evidence on its in vivo relevance in pathogenesis.

Milk sialyllactose influences colitis in mice through selective intestinal bacterial colonization

Milk oligosaccharides contribute to the development of the intestinal environment by acting as decoy receptors for pathogens and as prebiotics, which promote the colonization of commensal bacteria. Here, using α2,3- and α2,6-sialyltransferase-deficient mice, we investigated the role of the sialylated milk oligosaccharides sialyl(α2,3)lactose and sialyl(α2,6)lactose on mucosal immunity. The exposure of newborn mice to milk containing or deficient in sialyllactose had no impact on the development of mucosal leukocyte populations. However, when challenged by dextran sulfate sodium (DSS) in drinking water, adult mice that had been fostered on sialyl(α2,3)lactose-deficient milk were more resistant to colitis compared with mice fostered on normal milk or sialyl(α2,6)lactose-deficient milk. Analysis of intestinal microbiota showed different colonization patterns depending on the presence or absence of sialyl(α2,3)lactose in the milk. Germ-free mice reconstituted with intestinal microbiota isolated from mice fed on sialyl(α2,3)lactose-deficient milk were more resistant to DSS-induced colitis than germ-free mice reconstituted with standard intestinal microbiota. Thus, exposure to sialyllactose during infancy affects bacterial colonization of the intestine, which influences the susceptibility to DSS-induced colitis in adult mice.

Adhesive threads of extraintestinal pathogenic Escherichia coli

The ability to adhere to host surfaces is by far the most vital step in the successful colonization by microbial pathogens. Colonization begins with the attachment of the bacterium to receptors expressed by cells forming the lining of the mucosa. Long hair like extracellular appendages called fimbriae, produced by most Gram-negative pathogens, mediate specific attachment to the epithelial cell surface. Associated with the fimbriae is a protein called an adhesin, which directs high-affinity binding to specific cell surface components. In the last couple of years, an enormous amount of research has been undertaken that deals with understanding how bacterial pathogens adhere to host cells. E. coli in all probability is one of the best studied free-living organisms. A group of E. coli called Extraintestinal pathogenic E. coli (ExPEC) including both human and animal pathogens like Uropathogenic E. coli (UPEC), Newborn meningitic E. coli (NMEC) and Avian pathogenic E. coli (APEC), have been found to harbour many fimbriae including Type 1 fimbriae, P fimbriae, curli fibres, S fimbriae, F1C fimbriae, Dr fimbriae, afimbrial adhesins, temperature-sensitive haemagglutinin and many novel adhesin gene clusters that have not yet been characterized. Each of these adhesins is unique due to the recognition of an adhesin-specific receptor, though as a group these adhesins share common genomic organization. A newly identified putative adhesin temporarily termed ExPEC Adhesin I, encoded by gene yqi, has been recently found to play a significant role in the pathogenesis of APEC infection, thus making it an interesting candidate for future research. The aim of this review is to describe the role of ExPEC adhesins during extraintestinal infections known till date, and to suggest the idea of investigating their potential role in the colonization of the host gut which is said to be a reservoir for ExPEC.

Relationship between desert locust, Schistocerca gregaria (Forskål), infestation, environmental factors and control measures in Gazan and Makkah Regions, Saudi Arabia

Desert Locust, Schistocerca gregaria (Forskål), is one of the most important insect pests in Saudi Arabia. Cultivated crops and the range lands are heavily affected by desert locust in some regions of Saudi Arabia. The objective of this study was to determine the extent of damage by the Desert Locust, Schistocerca gregaria (Forskål) to the range lands being used for grazing range animals in Gazan and Makkah regions of Saudi Arabia. However, it is very difficult to estimate accurately the total infested areas, which were sprayed with insecticides to control upsurges, outbreaks and plagues over the last five decades. Records of Desert Locust control are kept in the National Desert Locust Control and Research Center in Jeddah. Meteorological data was obtained from the Meteorology and Environmental Protection Administration (MEPA), Saudi Arabia. The data shows that the Desert Locust infestation was associated partially with the rainfall intensity in Gazan and Makkah regions. There was found a good relationship between Desert Locust infestation (Solitary phase), temperature and the relative humidity. The locust infestation was heavy during 1986-88, 1992-95 and 1997-98 and about 1.8 million ha were treated with insecticides. Out of the total breeding/infested area, 43% was treated in winter months (October-February) and the remaining 57% was treated in spring season (March-June). The infested area was sprayed with Marshall, Carbosulfan (20%), Malathion (96%, Clorpyrifos; (48%) Fipronil (12.5%), Sumithion (100%) and Decis (12.5%). The study showed an excellent potential to determine the active locust infestation period in relation to the environmental factors for its effective control with insecticide sprays to minimize crop damage. The study highlighted the needs for further investigations in other locust infested areas with different environmental factors for planning future desert locust control programs.

Influence of type 1 piliation on chemotaxis and intracellular killing of uropathogenic E. coli by human polymorphonuclear leukocyts

Uropathogenic Escherichia coli (UPEC) that cause urinary tract infections bind to target cells via several distinct paris of adhesins and receptors. In this study we determine the role of type 1 pili in interaction of UPEC with human neutrophils. Type 1 piliated and unpiliated strains (obtained by growth at a pilus-restrictive temperature) of UPEC were used for determining the effect of this adhesin on migration of neutrophils towards bacteria in Boyden chamber. The lectinophagocytosis and intracellular killing of bacteria with purified human neutrophils were estimated by counting of the number of viable bacteria in 45 min. The results indicate that type 1 piliated UPEC stimulated significantly greater chemotaxis than did unpiliated bacteria and bacteria in which the piliation was suppressed. Phagocytosis of type 1 piliated UPEC occurred in the direct and opsonin-independent manner. In contrast, unpiliated bacteria failed to bind to PMN.

Role of the rapA gene in controlling antibiotic resistance of Escherichia coli biofilms

By using a high-throughput screening method, a mutant of a uropathogenic Escherichia coli strain affected in the rapA gene was isolated. The mutant formed normal-architecture biofilms but showed decreased penicillin G resistance, although the mutation did not affect planktonic cell resistance. Transcriptome analysis showed that 22 genes were down-regulated in the mutant biofilm. One of these genes was yhcQ, which encodes a putative multidrug resistance pump. Mutants with mutations in this gene also formed biofilms with decreased resistance, although the effect was less pronounced than that of the rapA mutation. Thus, an additional mechanism(s) controlled by a rapA-regulated gene(s) was involved in wild-type biofilm resistance. The search for this mechanism was guided by the fact that another down-regulated gene in rapA biofilms, yeeZ, is suspected to be involved in extra cell wall-related functions. A comparison of the biofilm matrix of the wild-type and rapA strains revealed decreased polysaccharide quantities and coverage in the mutant biofilms. Furthermore, the (fluorescent) functional penicillin G homologue Bocillin FL penetrated the mutant biofilms more readily. The results strongly suggest a dual mechanism for the wild-type biofilm penicillin G resistance, retarded penetration, and effective efflux. The results of studies with an E. coli K-12 strain pointed to the same conclusion. Since efflux and penetration can be general resistance mechanisms, tests were conducted with other antibiotics. The rapA biofilm was also more sensitive to norfloxacin, chloramphenicol, and gentamicin.

A second Aggregatibacter actinomycetemcomitans autotransporter adhesin exhibits specificity for buccal epithelial cells in humans and Old World primates

Previous work showed that the Aggregatibacter actinomycetemcomitans adhesin Aae demonstrated species specificity and tissue tropism to buccal epithelial cells (BECs) derived from humans and Old World primates, but a second, lower-affinity adhesin was noted. This study was designed to determine if Omp100 (also known as ApiA), a surface-expressed A. actinomycetemcomitans adhesin, is that second adhesin and if so to investigate its tissue tropism and species specificity. A targeted mutagenesis protocol was used to construct an isogenic apiA mutant and an aae apiA double mutant with wild-type A. actinomycetemcomitans. In addition, Escherichia coli strain DH5alpha was used to express apiA to further assess binding parameters. Results indicated that the apiA mutant strain showed significantly less binding to BECs than its parent strain (P < or = 0.05). Further, binding mediated by ApiA was specific to BECs from humans and Old World primates, as seen in both wild-type A. actinomycetemcomitans and E. coli expressing ApiA (P < or = 0.05). Pretreatment of wild-type A. actinomycetemcomitans cells with anti-ApiA antiserum reduced binding in a dose-dependent manner. The aae apiA double mutant completely abrogated A. actinomycetemcomitans binding to both human and Old World primate BECs. Taken together, these studies indicate that ApiA and Aae, in concert, modulate binding of A. actinomycetemcomitans to human BECs. Since the BEC is a prominent reservoir for A. actinomycetemcomitans, identification of this second adhesin could lead to important therapeutic strategies.

Sticky fibers and uropathogenesis: bacterial adhesins in the urinary tract

Adhesins mediate the introduction of bacteria to the host in the sometimes life-long relationship of uropathogenic Esherichia coli (UPEC) and the human urinary tract. As a class of extracellular proteins, adhesins enable bacteria to adhere to and, in some cases, invade host tissue; adhesins render UPEC virulent and permit host colonization. Adhesin receptor interactions at the host interface determine tissue tropism and disease progression in that niche, with each adhesin preferring unique sites within the urinary tract. This review focuses on known adhesins implicated in uropathogenesis, the structural basis of tissue tropism, postinvasion intracellular replication, current therapeutic design strategies, and newly discovered fimbrial gene clusters that may play a role in urinary tract infections.

Neuraminidase produces dose-dependent decrease of slime production and adherence of slime-forming, coagulase-negative staphylococci

BACKGROUND

Slime is one of the important structures of certain bacterial strains involved in nonspecific adherence. This study was conducted to determine the role of neuraminidase on slime formation and adherence of slime-forming coagulase-negative staphylococci to inert surface.

METHODS

Quantitative biofilm and qualitative bacterial adherence assays were performed with increasing concentrations of neuraminidase extracted from Clostridium perfringens-treated bacteria in polystyrene plates and polypropylene tubes.

RESULTS

Slime production of slime-forming, coagulase-negative staphylococci was significantly decreased dose dependently at > or =100 mU/mL (p <0.001). Bacterial adherence to smooth surface was impeded at > or =100 mU/mL of neuraminidase treatment and adherence results were comparable with slime production assay results.

CONCLUSIONS

Sialic acid may be a constituent molecule of slime and involved in bacterial adherence to inert surface. These results represent new insight into the mechanism of slime production and adherence of slime-forming, coagulase-negative staphylococci to inert surface.