Binding of Lactobacillus reuteri to fibronectin immobilized on glass beads

The Microbiome and Genitourinary Cancer: A Collaborative Review

CONTEXT

The recent discovery of the existence of a human genitourinary microbiome has led to the investigation of its role in mediating the pathogenesis of genitourinary malignancies, including bladder, kidney, and prostate cancers. Furthermore, although it is largely recognized that members of the gastrointestinal microbiota are actively involved in drug metabolism, new studies demonstrate additional roles and the potential necessity of the gastrointestinal microbiota in dictating cancer treatment response.

OBJECTIVE

To summarize the current evidence of a mechanistic role for the genitourinary and gastrointestinal microbiome in genitourinary cancer initiation and treatment response.

EVIDENCE ACQUISITION

We conducted a literature search up to October 2018. Search terms included microbiome, microbiota, urinary microbiome, bladder cancer, urothelial carcinoma, renal cell carcinoma, kidney cancer, testicular cancer, and prostate cancer.

EVIDENCE SYNTHESIS

There is preliminary evidence to implicate the members of the genitourinary microbiota as causative factors or cofactors in genitourinary malignancy. Likewise, the current evidence for gastrointestinal microbes in dictating cancer treatment response is mainly correlative; however, we provide examples where therapeutic agents used for the treatment of genitourinary cancers are affected by the human-associated microbiota, or vice versa. Clinical trials, such as fecal microbiota transplant to increase the efficacy of immunotherapy, are currently underway.

CONCLUSIONS

The role of the microbiome in genitourinary cancer is an emerging field that merits further studies. Translating microbiome research into clinical action will require incorporation of microbiome surveillance into ongoing and future clinical trials as well as expansion of studies to include metagenomic sequencing and metabolomics.

PATIENT SUMMARY

This review covers recent evidence that microbial populations that reside in the genitourinary tract-and were previously not known to exist-may influence the development of genitourinary malignancies including bladder, kidney, and prostate cancers. Furthermore, microbial populations that exist at sites outside of the genitourinary tract, such as those that reside in our gut, may influence cancer development and/or treatment response.

Lactobacilli at the front line of defense against vaginally acquired infections

Probiotics are microorganisms that provide a health benefit to the host and are promoted as alternatives for the treatment and prevention of infectious diseases and other conditions. One of the most rapidly developing areas of probiotic research is in the management of vaginally acquired infections. Several Lactobacillus species produce compounds that kill or inhibit the growth of vaginally acquired pathogens. Other lactobacilli reduce the adherence of pathogens to urogenital epithelial cells in culture. This article discusses the mechanisms by which vaginal lactobacilli prevent pathogen colonization of the urogenital tract, and potential mechanisms that warrant investigation. Animal models and clinical studies, while limited, are discussed with the idea that these are the next critical steps to advance the study of probiotics for the treatment and prevention of vaginally acquired infections.

Identification of a new adhesin-like protein from Lactobacillus mucosae ME-340 with specific affinity to the human blood group A and B antigens

AIMS

To identify and characterize a new adhesin-like protein of probiotics that show specific adhesion to human blood group A and B antigens.

METHODS AND RESULTS

Using the BIACORE assay, the adhesion of cell surface components obtained from four lactobacilli strains that adhered to blood group A and B antigens was tested. Their components showed a significant adhesion to A and B antigens when compared to the bovine serum albumin (BSA) control. The 1 mol l(-1) GHCl fraction extracted from Lactobacillus mucosae ME-340 contained a 29-kDa band (Lam29) using SDS-PAGE. The N-terminal amino acid sequence and homology analysis showed that Lam29 was 90% similar to the substrate-binding protein of the ATP-binding cassette (ABC) transporter from Lactobacillus fermentum IFO 3956. The complete nucleotide sequence (858 bp) of Lam29 was determined and encoded a protein of 285 amino acid residues. Phylogenetic analysis and multiple sequence alignments indicated this protein may be related to the cysteine-binding transporter.

CONCLUSIONS

The adhesion of ME-340 strain to blood group A and B antigens was mediated by Lam29 that is a putative component of ABC transporter as an adhesin-like protein.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus mucosae ME-340 expressing Lam29 may be useful for competitive exclusion of pathogens via blood group antigen receptors in the human gastrointestinal mucosa and in the development of new probiotic foods.

Adherence factors of Lactobacillus in the human gastrointestinal tract

Despite the increasing number of scientific reports describing adhesion of Lactobacillus to components of the human intestinal mucosa, information on the surface molecules mediating this adhesion and their corresponding receptors is fragmentary. This MiniReview compiles present knowledge of the genetically and functionally characterized Lactobacillus factors responsible for mediating adhesion to different components of the human gastrointestinal tract. In addition, for the proteins among these factors, the domain structure is discussed, and where appropriate the results of in silico analyses are reported.

A high-molecular-mass cell-surface protein from Lactobacillus reuteri 1063 adheres to mucus components

A gene from Lactobacillus reuteri 1063 encoding a cell-surface protein, designated Mub, that adheres to mucus components in vitro has been cloned and sequenced. The deduced amino acid sequence of Mub (358 kDa) shows the presence of 14 approximately 200 aa repeats and features typical for other cell-surface proteins of Gram-positive bacteria. Fusion proteins consisting of different repeats of Mub and the maltose-binding protein (MBP) were produced. These proteins adhered to pig mucus components, with molecular masses ranging from <0.1 to >2 MDa, to pig gastric mucin and to hen intestinal mucus. The binding of Mub to mucus components occurred in the pH range 3-7.4, with maximum binding at pH 4-5 and could be partly inhibited by the glycoprotein fetuin. Affinity-purified antibodies against recombinant Mub were used in immunofluorescence microscopy to demonstrate the presence of Mub on the cell surface of strain 1063. By using the antibodies in a Western blot analysis, Mub could also be detected in the growth medium. The results implicate Mub as a cell-surface protein that is involved in Lactobacillus interactions with mucin and in colonization of the digestive tract.

Autoaggregation of Lactobacillus reuteri is mediated by a putative DEAD-box helicase

We have cloned and sequenced a gene from Lactobacillus reuteri that encodes a 56 kDa protein, which mediates autoaggregation of the bacteria. Using an antiserum raised against extracellular proteins from the pig intestinal isolate L. reuteri 1063, we screened a genomic lambda library derived from the same strain. Affinity purification of recombinant protein from the isolated lambda clones showed that one type of clone expressed a protein that efficiently aggregated the parental strain when added to the bacteria. Subcloning and introduction of the corresponding gene, here denoted aggHinto the L. reuteri type strain markedly enhanced aggregation. Furthermore, insertional inactivation of aggH in strain 1063 resulted in an autoaggregation-deficient phenotype. Finally, an affinity-purified and cleaved fusion of AggH protein and the maltose-binding protein, MBP, strongly promoted aggregation of L. reuteri 1063, whereas the uncleaved fusion protein was inactive. Sequencing of aggH revealed that the corresponding protein has extensive sequence homology to the large family of ATP-dependent DEAD-box helicases. These results are intriguing in view of earlier data on the promotion of genetic exchange in Lactobacillus by aggregation.

A collagen binding protein from Lactobacillus reuteri is part of an ABC transporter system?

The gene coding for a collagen binding protein from Lactobacillus reuteri NCIB 11951 was cloned and sequenced. A genomic lambda library was constructed and recombinant plaques were screened using antisera raised against purified collagen binding proteins from the same L. reuteri strain. The positive plaques were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis, which revealed the expression of a 29 kDa protein, which reacted with the antisera and bound 125I-labelled type I collagen. The sequence of the corresponding gene, cnb showed that the collagen binding protein has sequence similarities to the solute binding component of bacterial ABC transporters.

Purification of collagen-binding proteins of Lactobacillus reuteri NCIB 11951

Collagen type-I-binding proteins of Lactobacillus reuteri NCIB 11951 were purified. The cell surface proteins were affinity purified on collagen Sepharose and eluted with an NaCl gradient. Two protein bands were eluted from the column (29 kDa and 31 kDa), and both bound radio-labeled collagen type I. Rabbit antisera raised against the 29 kDa and 31 kDa protein reacted with the affinity-purified proteins in a Western blot with whole-cell extract used as antigen. The N-terminal sequence of the 29-kDa and 31-kDa proteins demonstrated the closest homologies with internal sequences from an Escherichia coli trigger factor protein (TIG.ECOLI). Out of nine other lactobacilli, the antisera reacted only with the L. reuteri and not with the other species tested.