Alterations in Cortical Morphology after Neonatal Stroke: Compensation in the Contralesional Hemisphere?

Although neonatal arterial ischemic stroke is now well‐studied, its complex consequences on long‐term cortical brain development has not yet been solved. In order to understand the brain development after focal early brain lesion, brain morphometry needs to be evaluated using structural parameters. In this work, our aim was to study and analyze the changes in morphometry of ipsi‐ and contralesional hemispheres in seven‐year‐old children following neonatal stroke. Therefore, we used surface‐based morphometry in order to examine the cortical thickness, surface area, cortical volume, and local gyrification index in two groups of children that suffered from neonatal stroke in the left (n = 19) and right hemispheres (n = 15) and a group of healthy controls (n = 30). Reduced cortical thickness, surface area, and cortical volumes were observed in the ipsilesional hemispheres for both groups in comparison with controls. For the group with left‐sided lesions, higher gyrification of the contralesional hemisphere was observed primarily in the occipital region along with higher surface area and cortical volume. As for the group with right‐sided lesions, higher gyrification was detected in two separate clusters also in the occipital lobe of the contralesional hemisphere, without a significant change in cortical thickness, surface area, or cortical volume. This is the first time that alterations of structural parameters are detected in the “healthy” hemisphere after unilateral neonatal stroke indicative of a compensatory phenomenon. Moreover, findings presented in this work suggest that lesion lateralization might have an influence on brain development and maturation.     

Staphylococcus aureus Inhibits IL-8 Responses Induced by Pseudomonas aeruginosa in Airway Epithelial Cells

Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) are major respiratory pathogens and can concurrently colonize the airways of patients with chronic obstructive diseases, such as cystic fibrosis (CF). Airway epithelial cell signalling is critical to the activation of innate immune responses. In the setting of polymicrobial colonization or infection of the respiratory tract, how epithelial cells integrate different bacterial stimuli remains unknown. Our study examined the inflammatory responses to PA and SA co-stimulations. Immortalised airway epithelial cells (Beas-2B) exposed to bacteria-free filtrates from PA (PAF) induced a robust production of the neutrophil chemoattractant IL-8 while bacteria-free filtrates from SA (SAF) had a minimal effect. Surprisingly, co-stimulation with PAF+SAF demonstrated that SAF strongly inhibited the PAF-driven IL-8 production, showing that SAF has potent anti-inflammatory effects. Similarly SAF decreased IL-8 production induced by the TLR1/TLR2 ligand Pam₃CysSK₄ but not the TLR4 ligand LPS nor TLR5 ligand flagellin in Beas-2B cells. Moreover, SAF greatly dampened TLR1/TLR2-mediated activation of the NF-κB pathway, but not the p38 MAPK pathway. We observed this SAF-dependent anti-inflammatory activity in several SA clinical strains, as well as in the CF epithelial cell line CFBE41o-. These findings show a novel direct anti-inflammatory effect of SA on airway epithelial cells, highlighting its potential to modulate inflammatory responses in the setting of polymicrobial infections.     

Yeast-based production and purification of HIS-tagged human ATAD3A, A specific target of S100B

ATAD3 is a mitochondrial integral inner membrane ATPase with unknown function. ATAD3 is absent in yeast and protozoan and present in all pluricellular eucaryotes where its expression is essential for development. To date, bacterial-based expression of full-length ATAD3 has been unsuccessful because of very high levels of endogenous degradation. Based on Saccharomyces cerevisiae as a heterogeneous expression system, we engineered a high copy strain expressing human ATAD3A-Myc-HIS at a relative high level (2.5mg/l of yeast culture) without significantly affecting yeast growth. Most of the expressed human ATAD3A-Myc-HIS co-purified with the yeast mitochondrial fraction thus suggesting that targeting to this organelle is preserved in yeast. Like the endogenous protein in human cells, ATAD3A-Myc-HIS expressed in yeast is found resistant to extraction with salt and certain detergents, suggesting membrane insertion. Sarkosyl, C13-DAO, C12-DAO and ONMG efficiently solubilized ATAD3A-Myc-HIS from yeast extracts, but these soluble species did not bind to agarose-nickel matrix. By contrast, urea-denaturated ATAD3A-Myc-HIS bound to agarose-nickel beads and could be renatured and eluted to obtain highly pure ATAD3A-Myc-HIS. As the native protein in vivo, this recombinant, renatured species specifically bound in vitro to S100B and S100A1 in Far-Western assays.