An Interferon Signature Discriminates Pneumococcal From Staphylococcal Pneumonia

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). Despite the low prevalence of CAP caused by methicillin-resistant Staphylococcus aureus (MRSA), CAP patients often receive empirical antibiotic therapy providing coverage for MRSA such as vancomycin or linezolid. An early differentiation between S. pneumoniae and S. aureus pneumonia can help to reduce the use of unnecessary antibiotics. The objective of this study was to identify candidate biomarkers that can discriminate pneumococcal from staphylococcal pneumonia. A genome-wide transcriptional analysis of lung and peripheral blood performed in murine models of S. pneumoniae and S. aureus lung infection identified an interferon signature specifically associated with S. pneumoniae infection. Prediction models built using a support vector machine and Monte Carlo cross-validation, identified the combination of the interferon-induced chemokines CXCL9 and CXCL10 serum concentrations as the set of biomarkers with best sensitivity, specificity, and predictive power that enabled an accurate discrimination between S. pneumoniae and S. aureus pneumonia. The predictive performance of these biomarkers was further validated in an independent cohort of mice. This study highlights the potential of serum CXCL9 and CXCL10 biomarkers as an adjunctive diagnostic tool that could facilitate prompt and correct pathogen-targeted therapy in CAP patients

The type-2 Streptococcus canis M protein SCM-2 binds fibrinogen and facilitates antiphagocytic properties

Streptococcus canis is a zoonotic agent that causes severe invasive diseases in domestic animals and humans, but little is known about its pathogenesis and virulence mechanisms so far. SCM, the M-like protein expressed by S. canis, is considered one of the major virulence determinants. Here, we report on the two distinct groups of SCM. SCM-1 proteins were already described to interact with its ligands IgG and plasminogen as well as with itself and confer antiphagocytic capability of SCM-1 expressing bacterial isolates. In contrast, the function of SCM-2 type remained unclear to date. Using whole-genome sequencing and subsequent bioinformatics, FACS analysis, fluorescence microscopy and surface plasmon resonance spectrometry, we demonstrate that, although different in amino acid sequence, a selection of diverse SCM-2-type S. canis isolates, phylogenetically representing the full breadth of SCM-2 sequences, were able to bind fibrinogen. Using targeted mutagenesis of an SCM-2 isolate, we further demonstrated that this strain was significantly less able to survive in canine blood. With respect to similar studies showing a correlation between fibrinogen binding and survival in whole blood, we hypothesize that SCM-2 has an important contribution to the pathogenesis of S. canis in the host

Fluorescent Inorganic-Organic Hybrid Nanoparticles

Inorganic‐organic hybrid nanoparticles (IOH‐NPs) with a general composition [ZrO]2+[RDyeOPO3]2−, [Ln]3+n/3[RDye(SO3)n]n−, [Ln(OH)]2+n/2[RDye(SO3)n]n−, or [LnO]+n[RDye(SO3)n]n− (Ln: lanthanide) are a novel class of nanomaterials for fluorescence detection and optical imaging. IOH‐NPs are characterized by an extremely high load of the fluorescent dye (70–85 wt‐%), high photochemical stability, straightforward aqueous synthesis, low material complexity, intense emission and high cell uptake at low toxicity. Besides full‐color emission, IOH‐NPs are suitable for multimodal imaging, singlet‐oxygen generation as well as drug delivery and drug release. This focus review presents the material concept of the IOH‐NPs as well as their synthesis and characterization. Their characteristic features are illustrated by selected in vitro and in vivo studies to initiate application in biology and medicine

SEMPAI: a Self‐Enhancing Multi‐Photon Artificial Intelligence for Prior‐Informed Assessment of Muscle Function and Pathology

Deep learning (DL) shows notable success in biomedical studies. However, most DL algorithms work as black boxes, exclude biomedical experts, and need extensive data. This is especially problematic for fundamental research in the laboratory, where often only small and sparse data are available and the objective is knowledge discovery rather than automation. Furthermore, basic research is usually hypothesis‐driven and extensive prior knowledge (priors) exists. To address this, the Self‐Enhancing Multi‐Photon Artificial Intelligence (SEMPAI) that is designed for multiphoton microscopy (MPM)‐based laboratory research is presented. It utilizes meta‐learning to optimize prior (and hypothesis) integration, data representation, and neural network architecture simultaneously. By this, the method allows hypothesis testing with DL and provides interpretable feedback about the origin of biological information in 3D images. SEMPAI performs multi‐task learning of several related tasks to enable prediction for small datasets. SEMPAI is applied on an extensive MPM database of single muscle fibers from a decade of experiments, resulting in the largest joint analysis of pathologies and function for single muscle fibers to date. It outperforms state‐of‐the‐art biomarkers in six of seven prediction tasks, including those with scarce data. SEMPAI's DL models with integrated priors are superior to those without priors and to prior‐only approaches.The Self‐Enhancing Multi‐Photon AI (SEMPAI) that is designed specifically for basic laboratory research with microscopy is presented. It allows to integrate hypotheses and uses meta‐learning in a biologically interpretable configuration space for knowledge discovery. SEMPAI is applied to a large database of multi‐photon microscopy images of single muscle fibers to gain a deeper understanding of structure–function relationships and pathologies. image European Union's Horizon Marie Skłodowska‐Curie2021 Emerging Talents Initiative of the Friedrich‐Alexander UniversityGerman Research Foundation http://dx.doi.org/10.13039/50110000165

Itaconate controls its own synthesis via feedback-inhibition of reverse TCA cycle activity at IDH2.

peer reviewedMacrophages undergo extensive metabolic reprogramming during classical pro-inflammatory polarization (M1-like). The accumulation of itaconate has been recognized as both a consequence and mediator of the inflammatory response. In this study we first examined the specific functions of itaconate inside fractionated mitochondria. We show that M1 macrophages produce itaconate de novo via aconitase decarboxylase 1 (ACOD1) inside mitochondria. The carbon for this reaction is not only supplied by oxidative TCA cycling, but also through the reductive carboxylation of α-ketoglutarate by isocitrate dehydrogenase (IDH). While macrophages are capable of sustaining a certain degree of itaconate production during hypoxia by augmenting the activity of IDH-dependent reductive carboxylation, we demonstrate that sufficient itaconate synthesis requires a balance of reductive and oxidative TCA cycle metabolism in mouse macrophages. In comparison, human macrophages increase itaconate accumulation under hypoxic conditions by augmenting reductive carboxylation activity. We further demonstrated that itaconate attenuates reductive carboxylation at IDH2, restricting its own production and the accumulation of the immunomodulatory metabolites citrate and 2-hydroxyglutarate. In line with this, reductive carboxylation is enhanced in ACOD1-depleted macrophages. Mechanistically, the inhibition of IDH2 by itaconate is linked to the alteration of the mitochondrial NADP+/NADPH ratio and competitive succinate dehydrogenase inhibition. Taken together, our findings extend the current model of TCA cycle reprogramming during pro-inflammatory macrophage activation and identified novel regulatory properties of itaconate

Major role for active extension in the formation of processes by ras -transformed fibroblasts

Expression of constitutively active Ras protein in fibroblasts results in enhanced cell motility, invasion competence and morphological changes including the formation of elongate cellular processes. These processes have been shown to resemble retraction tails formed passively behind nontransformed cells by movement relative to sites of cell-substrate attachment. However, analysis presented here reveals that active extension mechanisms also play a role in the formation of these processes. Extension of distal process ends occurs at 0.42 ± 0.44 μm/min in ras -transformed fibroblasts and accounts for 63.6 ± 27.5% of observed process lengths. Active process extension by ras -transformed fibroblasts also persists in the presence of cell-cell contacts. Studies conducted using actin or microtubule antagonists, and correlation of process behavior followed by fixation and immunostaining reveal that process extension requires intact actin and microtubule networks. Other analyses reveal that active extension plays a significantly smaller role in the formation of processes by non-transformed control fibroblasts. These observations demonstrate that constitutively active Ras enhances process extension in fibroblasts and is a causal factor in process extension by fibroblasts in the presence of cell-cell contacts. Moreover, these studies demonstrate that process extension by ras -transformed fibroblasts is accomplished through mechanisms similar to those thought to drive active extension of processes by other cell types including neurons. These findings suggest that extension of cellular processes could play an important role in the metastatic behavior of ras -transformed fibroblasts as well as the response of untransformed fibroblasts to receptor mediated signal transduction events. Cell Motil. Cytoskeleton 42:12–26, 1999. © 1999 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34964/1/2_ftp.pd

Mesaconate is synthesized from itaconate and exerts immunomodulatory effects in macrophages.

peer reviewedSince its discovery in inflammatory macrophages, itaconate has attracted much attention due to its antimicrobial and immunomodulatory activity1-3. However, instead of investigating itaconate itself, most studies used derivatized forms of itaconate and thus the role of non-derivatized itaconate needs to be scrutinized. Mesaconate, a metabolite structurally very close to itaconate, has never been implicated in mammalian cells. Here we show that mesaconate is synthesized in inflammatory macrophages from itaconate. We find that both, non-derivatized itaconate and mesaconate dampen the glycolytic activity to a similar extent, whereas only itaconate is able to repress tricarboxylic acid cycle activity and cellular respiration. In contrast to itaconate, mesaconate does not inhibit succinate dehydrogenase. Despite their distinct impact on metabolism, both metabolites exert similar immunomodulatory effects in pro-inflammatory macrophages, specifically a reduction of interleukin (IL)-6 and IL-12 secretion and an increase of CXCL10 production in a manner that is independent of NRF2 and ATF3. We show that a treatment with neither mesaconate nor itaconate impairs IL-1β secretion and inflammasome activation. In summary, our results identify mesaconate as an immunomodulatory metabolite in macrophages, which interferes to a lesser extent with cellular metabolism than itaconate