HIV-1 Persistenz in humanen neuralen Progenitorpopulationen

HIV-1 ist ein neurotrophes Virus und kann im Gehirn über Jahre verbleiben. Während bekannt ist, dass Astrozyten ein zelluläres Reservoir für das Virus im Gehirn bilden, ist die Infektion anderer neuraler Zellen des ZNS noch ziemlich unklar. Neurale Progenitorzellen sind mulitpotente, sich selbsterneuernden Zellen des fetalen und des adulten Gehirns, die in der Lage sind, sich in Neuronen, Oligodendrozyten und Astrozyten zu differenzieren. Es konnte bereits gezeigt werden, dass diese Zellen durch das HI-Virus infiziert werden können. Ziel der vorliegenden Arbeit war nun, zu untersuchen, ob diese Zellpopulation ein weiteres mögliches Reservoir für das Virus darstellen könnte. Als Zellkulturmodell wurde die neurale Progenitorzelllinie HNSC.100 verwendet. Sie konnte zum einen als proliferierende Progenitorpopulation kultiviert werden und zum anderen auch, nach gezielter Differenzierung mittels des Zytokins CNTF, als Modellsystem für Astrozyten. Die beiden HNSC.100-Populationen zeigten verlässliche funktionale und phenotypische Unterschiede. Zur Untersuchung des Differenzierungsstatuses konnte eine transgene Zellpopulation etabliert werden, welche eine differenzierungsabhängige Expression des EGFP-Proteins zeigt. Die Progenitorzelllinie HNSC.100 wurden mittels zellfreiem HIV-1 infiziert und die HIV-Infektion über einen Zeitraum von vier Monaten untersucht. Die Bestimmung der Proviruskopienzahl zeigte, dass die Zellpopulation während der gesamten Beobachtungsperiode infiziert blieb. Die infizierte Progenitorpopulation setzte über 60 Tage lang moderate Mengen an HIV frei, danach sank die Virusproduktion der Zellen ab. Die Progenitorzellen bildeten jedoch weiterhin virale RNA-Transkripte. Durch Induktion der Astrogenese oder Behandlung der Zellen mit dem proinflammatorischen Zytokin TNF- konnte die Virusproduktion der infizierten Progenitorzellen vorübergehend wieder aktiviert werden. Die Langzeit-Infektion der neuralen Progenitorpopulation hatte Auswirkungen auf einige zelluläre Eigenschaften der Zellen: die GFAP-Produktion der Zellen nahm im Verlauf der Infektion zu, die Zellen zeigten eine veränderte Zellmorphologie und die Differenzierung in reife Neuronen war beeinträchtigt. Diese Ergebnisse zeigen, dass HIV in neuralen Progenitorzellpopulationen persistieren kann und dabei zelluläre Eigenschaften der Population verändert

Targeting TRAF6 E3 ligase activity with a small-molecule inhibitor combats autoimmunity

Constitutive NF-B signaling represents a hallmark of chronic inflammation and autoimmune diseases. The E3 ligase TNF receptor-associated factor 6 (TRAF6) acts as a key regulator bridging innate immunity, pro-inflammatory cytokines, and antigen receptors to the canonical NF-B pathway. Structural analysis and point mutations have unraveled the essential role of TRAF6 binding to the E2-conjugating enzyme ubiquitin-conjugating enzyme E2 N (Ubc13 or UBE2N) to generate Lys63-linked ubiquitin chains for inflammatory and immune signal propagation. Genetic mutations disrupting TRAF6 -Ubc13 binding have been shown to reduce TRAF6 activity and, consequently, NF-B activation. However, to date, no small-molecule modulator is available to inhibit the TRAF6 -Ubc13 interaction and thereby counteract NF-B signaling and associated diseases. Here, using a high-throughput small-molecule screening approach, we discovered an inhibitor of the TRAF6 -Ubc13 interaction that reduces TRAF6 -Ubc13 activity both in vitro and in cells. We found that this compound, C25-140, impedes NF-B activation in various immune and inflammatory signaling pathways also in primary human and murine cells. Importantly, C25-140 ameliorated inflammation and improved disease outcomes of autoimmune psoriasis and rheumatoid arthritis in preclinical in vivo mouse models. Hence, the first-in-class TRAF6 -Ubc13 inhibitor C25-140 expands the toolbox for studying the impact of the ubiquitin system on immune signaling and underscores the importance of TRAF6 E3 ligase activity in psoriasis and rheumatoid arthritis. We propose that inhibition of TRAF6 activity by small molecules represents a promising novel strategy for targeting autoimmune and chronic inflammatory diseases

Acriflavine, a clinically approved drug, inhibits SARS-CoV-2 and other betacoronaviruses

The COVID-19 pandemic caused by SARS-CoV-2 has been socially and economically devastating. Despite an unprecedented research effort and available vaccines, effective therapeutics are still missing to limit severe disease and mortality. Using high-throughput screening, we identify acriflavine (ACF) as a potent papain-like protease (PLpro) inhibitor. NMR titrations and a co-crystal structure confirm that acriflavine blocks the PLpro catalytic pocket in an unexpected binding mode. We show that the drug inhibits viral replication at nanomolar concentration in cellular models, in vivo in mice and ex vivo in human airway epithelia, with broad range activity against SARS-CoV-2 and other betacoronaviruses. Considering that acriflavine is an inexpensive drug approved in some countries, it may be immediately tested in clinical trials and play an important role during the current pandemic and future outbreaks. © 2021 The Author

ABCA3 Deficiency—Variant-Specific Response to Hydroxychloroquine

Biallelic variants in ABCA3, the gene encoding the lipid transporter ATP-binding cassette subfamily A member 3 (ABCA3) that is predominantly expressed in alveolar type II cells, may cause interstitial lung diseases in children (chILD) and adults. Currently, there is no proven therapy, but, frequently, hydroxychloroquine (HCQ) is used empirically. We hypothesized that the in vitro responsiveness to HCQ might correlate to patients’ clinical outcomes from receiving HCQ therapy. The clinical data of the subjects with chILD due to ABCA3 deficiency and treated with HCQ were retrieved from the literature and the Kids Lung Register data base. The in vitro experiments were conducted on wild type (WT) and 16 mutant ABCA3-HA-transfected A549 cells. The responses of the functional read out were assessed as the extent of deviation from the untreated WT. With HCQ treatment, 19 patients had improved or unchanged respiratory conditions, and 20 had respiratory deteriorations, 5 of whom transiently improved then deteriorated. The in vitro ABCA3 functional assays identified two variants with complete response, five with partial response, and nine with no response to HCQ. The variant-specific HCQ effects in vivo closely correlated to the in vitro data. An ABCA3+ vesicle volume above 60% of the WT volume was linked to responsiveness to HCQ; the HCQ treatment response was concentration dependent and differed for variants in vitro. We generated evidence for an ABCA3 variant-dependent impact of the HCQ in vitro. This may also apply for HCQ treatment in vivo, as supported by the retrospective and uncontrolled data from the treatment of chILD due to ABCA3 deficiency

CellDeathPred: a deep learning framework for ferroptosis and apoptosis prediction based on cell painting

Abstract Cell death, such as apoptosis and ferroptosis, play essential roles in the process of development, homeostasis, and pathogenesis of acute and chronic diseases. The increasing number of studies investigating cell death types in various diseases, particularly cancer and degenerative diseases, has raised hopes for their modulation in disease therapies. However, identifying the presence of a particular cell death type is not an obvious task, as it requires computationally intensive work and costly experimental assays. To address this challenge, we present CellDeathPred, a novel deep-learning framework that uses high-content imaging based on cell painting to distinguish cells undergoing ferroptosis or apoptosis from healthy cells. In particular, we incorporate a deep neural network that effectively embeds microscopic images into a representative and discriminative latent space, classifies the learned embedding into cell death modalities, and optimizes the whole learning using the supervised contrastive loss function. We assessed the efficacy of the proposed framework using cell painting microscopy data sets from human HT-1080 cells, where multiple inducers of ferroptosis and apoptosis were used to trigger cell death. Our model confidently separates ferroptotic and apoptotic cells from healthy controls, with an average accuracy of 95% on non-confocal data sets, supporting the capacity of the CellDeathPred framework for cell death discovery

New small molecules targeting apoptosis and cell viability in osteosarcoma.

Despite the option of multimodal therapy in the treatment strategies of osteosarcoma (OS), the most common primary malignant bone tumor, the standard therapy has not changed over the last decades and still involves multidrug chemotherapy and radical surgery. Although successfully applied in many patients a large number of patients eventually develop recurrent or metastatic disease in which current therapeutic regimens often lack efficacy. Thus, new therapeutic strategies are urgently needed. In this study, we performed a phenotypic high-throughput screening campaign using a 25,000 small-molecule diversity library to identify new small molecules selectively targeting osteosarcoma cells. We could identify two new small molecules that specifically reduced cell viability in OS cell lines U2OS and HOS, but affected neither hepatocellular carcinoma cell line (HepG2) nor primary human osteoblasts (hOB). In addition, the two compounds induced caspase 3 and 7 activity in the U2OS cell line. Compared to conventional drugs generally used in OS treatment such as doxorubicin, we indeed observed a greater sensitivity of OS cell viability to the newly identified compounds compared to doxorubicin and staurosporine. The p53-negative OS cell line Saos-2 almost completely lacked sensitivity to compound treatment that could indicate a role of p53 in the drug response. Taken together, our data show potential implications for designing more efficient therapies in OS

Identification of Small-Molecule Frequent Hitters from AlphaScreen High-Throughput Screens

Although small-molecule drug discovery efforts have focused largely on enzyme, receptor, and ion-channel targets, there has been an increase in such activities to search for protein-protein interaction (PPI) disruptors by applying high-throughout screening (HTS)-compatible protein-binding assays. However, a disadvantage of these assays is that many primary hits are frequent hitters regardless of the PPI being investigated. We have used the AlphaScreen technology to screen four different robust PPI assays each against 25,000 compounds. These activities led to the identification of 137 compounds that demonstrated repeated activity in all PPI assays. These compounds were subsequently evaluated in two AlphaScreen counter assays, leading to classification of compounds that either interfered with the AlphaScreen chemistry (60 compounds) or prevented the binding of the protein His-tag moiety to nickel chelate (Ni2+-NTA) beads of the AlphaScreen detection system (77 compounds). To further triage the 137 frequent hitters, we subsequently confirmed by a time-resolved fluorescence resonance energy transfer assay that most of these compounds were only frequent hitters in AlphaScreen assays. A chemoinformatics analysis of the apparent hits provided details of the compounds that can be flagged as frequent hitters of the AlphaScreen technology, and these data have broad applicability for users of these detection technologies

IC50 values for the new compounds A13 and H12, and for staurosporine.

<p>Dose-response curves for the indicated compounds and cell lines are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0129058#pone.0129058.s001" target="_blank">S1 Fig</a>. In some cells and for doxorubicin in total the IC50 value could not be determined (n.d.), because no sigmoidal dose-response curves could be obtained.</p><p>IC50 values for the new compounds A13 and H12, and for staurosporine.</p