"More Guts Than Brains?"-The Role of Gut Microbiota in Idiopathic Intracranial Hypertension.

BACKGROUND: Idiopathic intracranial hypertension syndrome (IIH) is most common among obese women. Weight loss is an important factor in improving papilledema. Over the last decade, growing evidence has identified gut microbiota as a potential factor in the pathophysiology of obesity. Accordingly, we investigated whether the gut microbiome is modified in IIH patients compared with healthy controls, and provide possible new treatment venues. METHODS: Shotgun metagenomic sequencing of the gut microbiome of 25 cases of IIH patients (according to the modified Dandy criteria) and 20 healthy controls. Participants were further stratified according to their body mass index. The total DNA from each sample was extracted using the PureLink Microbiome DNA Purification Kit A29789 (Invitrogen, Thermo Fisher Scientific, US). Library preparation was performed using the Nextera DNA Flex Library Prep Kit. Samples were sequenced on the Illumina Novaseq 6000 device. A list of bacterial species that significantly differed between the IIH patients and healthy controls was produced in addition to species diversity. In addition, patients' cohort alone was analyzed, (excluding the healthy controls), and the effect of acetazolamide treatment on their gut microbiota was analyzed. RESULTS: IIH patients have a lower diversity of bacterial species compared with healthy individuals. These bacteria, that is, Lactobacillus ruminis (L. ruminis) (p<6.95E-08), Atopobium parvulum (p<3.9E-03), Megamonas hypermegale (p<5.61E-03), Ruminococcus gnavus (p<1.29E-02), MEL.A1 (p<3.04E-02), and Streptococcus sp. I-G2 (p<3.04E-02), were previously characterized with beneficial health effects. Moreover, we found that Lactobacillus brevis, a beneficial bacterium as well, is more abundant in acetazolamide treated patients (p<7.07E-06). CONCLUSIONS: Gut microbiota plays a potential role in IIH etiology and therefore, can provide a promising new treatment approach for this disease.

Mechanical interactions of invasive cancer cells through their substrate evolve from additive to synergistic.

Non-contacting, adjacent cancer cells can mechanically interact through their substrate to increase their invasive and migratory capacities that underly metastases-formation. Such mechanical interactions may induce additive or synergistic enhancement of invasiveness, potentially indicating different underlying force-mechanisms. To identify cell-cell-gel interactions, we monitor the time-evolution of three-dimensional traction strains induced by MDA-MB-231 breast cancer cells adhering on physiological-stiffness (1.8 kPa) collagen gels and compare to simulations. Single metastatic cells apply strain energies of 0.2-2 pJ (average 0.51 ± 0.06 pJ) at all observation times (30-174 min) inducing a mechanical volume-of-effect in the collagen gel that is initially (<60 min from seeding) on the cell-volume scale (∼3000 µm3) and on average increases with time from cell seeding. When cells adhere closely adjacent, at short times (<60 min) we distinguish the additive contributions of neighboring cells to the strains, while at longer times strain fields are synergistically amplified and may facilitate increased cooperative/collective cancer-cell-invasiveness. The results of well-spaced and closely adjacent cells at short times match our simulations of additive deformations induced by radially applied strains with experimentally based inverse-distance decay. We thus reveal a time-dependent evolution from additive to synergistic interactions of adjacently adhering cells that may facilitate metastatic invasion.

Two- and three-dimensional de-drifting algorithms for fiducially marked image stacks.

Traction force microscopy has been established as the accepted method for evaluating cell-induced mechanical stresses to their microenvironments, typically using two-dimensional (2D) elastic, synthetic gel-substrates. As cells naturally experience 3D environments in vivo, traction microscopy has been adapted to 3D gels; cells can be tracked over time in 3D. Microscopy images acquired in several fields-of-view e.g. in a time series, may experience drift, which can produce artefactual results that may appear valid and lead to flawed analysis. Hence, we have developed an algorithm for 2D/3D de-drifting of cell-images on 3D gels with fiducial markers (beads) as anchor points. Both lateral and vertical de-drifting are performed using gel-internalized beads, as those used in traction microscopy experiments; this eliminates need for immobilizing beads under the gel for de-drifting, and reduces experiment time. We introduce simulations of initially grid-ordered dots (beads) that are radially displaced to experimentally observed distances, while also applying additive drift. This facilitates testing and demonstration of the de-drifting procedures in 2D/3D. We demonstrate the importance of applying de-drifting using both computer-simulated drifts and experimentally observed drifts in confocal microscopy images. We show that our de-drifting algorithm can remove lateral and/or vertical drift revealing even small, underlying signals. The 2D/3D de-drifting algorithm, crucial for accurate identification of cell-induced marker-displacement, as well as the bead simulations, will shorten traction microscopy experiments and facilitate optimization of the experimental protocols.