Three-dimensional modeling of the human fallopian tube fimbriae

OBJECTIVE: Ovarian cancer is the most lethal gynecological malignancy that affects women. Recent data suggests that the disease may originate in the fallopian fimbriae; however, the anatomical origin of ovarian carcinogenesis remains unclear. This is largely driven by our lack of knowledge regarding the structure and function of normal fimbriae and the relative paucity of models that accurately recapitulate the in vivo fallopian tube. Therefore, a human three-dimensional (3D) culture system was developed to examine the role of the fallopian fimbriae in serous tumorigenesis.

METHODS: Alginate matrix was utilized to support human fallopian fimbriae ex vivo. Fimbriae were cultured with factors hypothesized to contribute to carcinogenesis, namely; H2O2 (1mM) a mimetic of oxidative stress, insulin (5μg/ml) to stimulate glycolysis, and estradiol (E2, 10nM) which peaks before ovulation. Cultures were evaluated for changes in proliferation and p53 expression, criteria utilized to identify potential precursor lesions. Further, secretory factors were assessed after treatment with E2 to identify if steroid signaling induces a pro-tumorigenic microenvironment.

RESULTS: 3D fimbriae cultures maintained normal tissue architecture up to 7days, retaining both epithelial subtypes. Treatment of cultures with H2O2 or insulin significantly induced proliferation. However, p53 stabilization was unaffected by any particular treatment, although it was induced by ex vivo culturing. Moreover, E2-alone treatment significantly induced its canonical target PR and expression of IL8, a factor linked to poor outcome.

CONCLUSIONS: 3D alginate cultures of human fallopian fimbriae provide an important microphysiological model, which can be further utilized to investigate serous tumorigenesis originating from the fallopian tube.

Predatory Bdellovibrio bacteria use gliding motility to scout for prey on surfaces

Bdellovibrio bacteriovorus is a famously fast, flagellate predatory bacterium, preying upon Gram-negative bacteria in liquids; how it interacts with prey on surfaces such as in medical biofilms is unknown. Here we report that Bdellovibrio bacteria "scout" for prey bacteria on solid surfaces, using slow gliding motility that is present in flagellum-negative and pilus-negative strains.

A predatory patchwork:membrane and surface structures of Bdellovibrio bacteriovorus

Predatory Bdellovibrio bacteriovorus bacteria are remarkable in that they attach to, penetrate and digest other Gram-negative bacteria, living and replicating within them until all resources are exhausted, when they escape the prey ghost to invade fresh prey. Remarkable remodeling of both predator and prey cell occurs during this process to allow the Bdellovibrio to exploit the intracellular niche they have worked so hard to enter, keeping the prey "bdelloplast" intact until the end of predatory growth. If one views motile non-predatory bacteria in a light microscope, one is immediately struck by how rare it is for bacteria to collide. This highlights how the cell surface of Bdellovibrio must be specialized and adapted to allow productive collisions and further to allow entry into the prey periplasm and subsequent secretion of hydrolytic enzymes to digest it. Bdellovibrio can, however, also be made to grow artificially without prey; thus, they have a large genome containing both predatory genes and genes for saprophytic heterotrophic growth. Thus, the membrane and outer surface layers are a patchwork of proteins encompassing not only those that have a sole purpose in heterotrophic growth but also many more that are specialized or employed to attach to, enter, remodel, kill and ultimately digest prey cells. There is much that is as yet not understood, but molecular genetic and post-genomic approaches to microbial physiology have enhanced the pioneering biochemical work of four decades ago in characterizing some of the key events and surface protein requirements for prey attack.

The influence of microbial factors on the susceptibility of bacteria to photocatalytic destruction

The role that bacterial factors play in determining how bacteria respond to photocatalytic degradation is becoming increasingly recognised. Fimbriae which are thin, proteinaceous cell surface structures produced by many enterobacteria are generally considered to be important bacterial virulence determinants in the host. Recent studies, however, suggest that their expression may be increased during times of environmental stress to protect them against factors such as nutrient depletion and oxidation. In this study bacteria were grown under defined culture conditions to promote the expression of type 1 fimbriae and subjected to photocatalytic treatment. Results showed that Escherichia coli grown under conditions to express type 1 fimbriae were more resistant to photocatalytic destruction than control cultures, taking 75 min longer to be destroyed. Curli fimbriae are also known to play a role in environmental protection of bacteria and they are associated with biofilm production. The ability of the E. coli strain to produce curli fimbriae was confirmed and biofilms were grown and subjected to photocatalytic treatment. Biofilm destruction by photocatalysis was assessed using a resazurin viability assay and a loss of cell viability was demonstrated within 30 min treatment time. This study suggests that intrinsic bacterial factors may play a role in determining an organism’s response to photocatalytic treatment and highlights their importance in this disinfection process.