In parallel to the Th1/Th2 paradigm, antigen-presenting cells (APC) are divided into classically activated APC (dendritic cells/effector macrophages) and alternatively activated APC (IL-4-induced, alternatively activated macrophages/IL-10-induced, immature dendritic cells). Alternatively activated APC share a special molecular repertoire including receptors of innate immunity with broad specificity for foreign antigen and anti-inflammatory cytokines such as IL-1Ra and alternative macrophage activation-associated CC-chemokine-1. Alternatively activated APC mediated tolerance and downregulated inflammation. Abuse of alternatively activated APC in support of infectious susceptibility or tumor immune escape is counteracted by the classical pathway. Thus, classically and alternatively activated APC secure the balance between proinflammatory and anti-inflammatory immune reactions.

Alternative activation of macrophages, induced by Th 2 cytokines and glucocorticoids, is essential for the proper functioning of anti-inflammatory immune reactions. To this end, alternatively activated macrophages (aaMF) express a not yet fully unravelled set of genes including cytokines such as alternative macrophage activation-associated CC-chemokine (AMAC)-1 and pattern recognition molecules such as the scavenger receptor CD163. In order to further characterize the molecular repertoire of aaMF, differential gene expression was analyzed by combining subtractive suppression cloning and differential hybridization. We show here that aaMF induced by interleukin (IL)-4 overexpress the prototype extracellular matrix (ECM) protein fibronectin on the mRNA and protein level. This overall increase is accompanied by a shift in fibronectin splice variants from an embryonic to a mature pattern. In addition, the expression of another ECM protein, bIG-H3, is also upregulated by IL-4 in aaMF. In contrast to IL-4 and in line with its inhibitory effect on wound healing, dexamethasone exerts a strongly suppressive effect on fibronectin and bIG-H3 expression. In conclusion, overexpression of ECM proteins induced by IL-4 in macrophages suggests that aaMF may be involved in ECM deposition and tissue remodelling during the healing phase of acute inflammatory reactions and in chronic inflammatory diseases.

Understanding how distributed neuronal circuits integrate sensory information and generate behavior is a central goal of neuroscience. Yet, studying neuronal networks at single-cell resolution across the entire adult brain has been difficult in vertebrates due to their size and opacity. We address this challenge by introducing the fish Danionella translucida as a model organism to neuroscience. This teleost remains small and transparent even in adulthood, when neural circuits and behavior have matured. Despite its small brain, Danionella displays a rich set of complex behaviors, including courtship, shoaling, schooling and acoustic communication. To enable optical activity measurements and perturbations with genetically encoded tools, we established CRISPR/Cas9 genome editing and Tol2 transgenesis techniques. These features make Danionella translucida a promising model organism for the study of adult vertebrate brain function at single-cell resolution.

BackgroundTo functionally characterize pro-inflammatory and vasoconstrictive properties of cerebrospinal fluid after aneurysmal subarachnoid hemorrhage (SAH) in vivo and in vitro.MethodsThe cerebrospinal fluid (CSF) of 10 patients suffering from SAH was applied to the transparent skinfold chamber model in male NMRI mice which allows for in vivo analysis of the microcirculatory response to a superfusat. Microvascular diameter changes were quantified and the numbers of rolling and sticking leukocytes were documented using intravital multifluorescence imaging techniques. Furthermore, the pro-inflammatory properties of CSF were assessed in vitro using a monocyte transendothelial migration assay.ResultsCSF superfusion started to induce significant vasoconstriction on days 4 and 6 after SAH. In parallel, CSF superfusion induced a microvascular leukocyte recruitment, with a significant number of leukocytes rolling (day 6) and sticking (days 2-4) to the endothelium. CSF of patients presenting with cerebral edema induced breakdown of blood vessel integrity in our assay as evidenced by fluorescent marker extravasation. In accordance with leukocyte activation in vivo, significantly higher in vitro monocyte migration rates were found after SAH.ConclusionWe functionally characterized inflammatory and vasoactive properties of patients' CSF after SAH in vivo and in vitro. This pro-inflammatory milieu in the subarachnoid space might play a pivotal role in the pathophysiology of early and delayed brain injury as well as vasospasm development following SAH.