Neonatal imprinting of alveolar macrophages via neutrophil-derived 12-HETE.

Resident-tissue macrophages (RTMs) arise from embryonic precursors1,2, yet the developmental signals that shape their longevity remain largely unknown. Here we demonstrate in mice genetically deficient in 12-lipoxygenase and 15-lipoxygenase (Alox15-/- mice) that neonatal neutrophil-derived 12-HETE is required for self-renewal and maintenance of alveolar macrophages (AMs) during lung development. Although the seeding and differentiation of AM progenitors remained intact, the absence of 12-HETE led to a significant reduction in AMs in adult lungs and enhanced senescence owing to increased prostaglandin E2 production. A compromised AM compartment resulted in increased susceptibility to acute lung injury induced by lipopolysaccharide and to pulmonary infections with influenza A virus or SARS-CoV-2. Our results highlight the complexity of prenatal RTM programming and reveal their dependency on in trans eicosanoid production by neutrophils for lifelong self-renewal.

Biomimetic Desymmetrization of a Carboxylic Acid.

The enantioselective desymmetrization of carboxylic acids by chiral Brønsted base catalysis is reported, leading to bridged bicyclic lactones with up to 94% ee. Crystallographic analysis of a substrate-catalyst complex suggests an origin of stereocontrol, reminiscent of functional Brønsted bases in biological settings, and enabled reaction optimization. The products contain an all-carbon quaternary stereocenter and can be derivatized to functionalized cyclopentanes.

Detection of nitroaromatics in the solid, solution, and vapor phases using silicon quantum dot sensors.

Silicon quantum dots (Si-QDs) represent a well-known QD fluorophore that can emit throughout the visible spectrum depending on the interface structure and surface functional group. Detection of nitroaromatic compounds by monitoring the luminescence response of the sensor material (typically fluorescent polymers) currently forms the basis of new explosives sensing technologies. Freestanding silicon QDs may represent a benign alternative with a high degree of chemical and physical versatility. Here, we investigate dodecyl and amine-terminated Si-QD luminescence response to the presence of nitrobenzene and dinitrotoluene (DNT) in various solid, solution, and vapor forms. For dinitrotoluene vapor the 3σ detection limit was 6 ppb for monomer-terminated QDs. For nitroaromatics dissolved in toluene the detection limit was on the order of 400 nM, corresponding to ∼100 pg of material distributed over ∼1 cm(2) on the sensor surface. Solid traces of nitroaromatics were also easily detectable via a simple 'touch test'. The samples showed minimal interference effects from common contaminants such as water, ethanol, and acetonitrile. The sensor can be as simple and inexpensive as a small circle of filter paper dipped into a QD solution, with a single vial of QDs able to make hundreds of these sensors. Additionally, a trial fiber-optic sensor device was tested by applying the QDs to one end of a 2 × 2 fiber coupler and exposing them to controlled DNT vapor. Finally, the quenching mechanism was explored via luminescence dynamics measurements and is different for blue (amine) and red (dodecyl) fluorescent silicon QDs.

Alendronate modulates cytokine responses in healthy young individuals after BCG vaccination.

Bacillus Calmette-Guérin (BCG) vaccination induces memory characteristics in innate immune cells and their progenitors, a process called trained immunity mediated by epigenetic and metabolic reprogramming. Cholesterol synthesis plays an amplifying role in trained immunity through mevalonate release. Nitrogen-containing bisphosphonates (N-BPs), such as alendronate, can inhibit cholesterol synthesis. We explored their effects on trained immunity induced by BCG in a placebo-controlled clinical study (NL74082.091.20) in young, healthy individuals. Participants receiving single-dose oral alendronate on the day of BCG vaccination had more neutrophils and plasma cells one month after treatment. Alendronate led to reduced proinflammatory cytokine production by PBMCs stimulated with heterologous bacterial and viral stimuli one month later. Furthermore, the addition of alendronate transcriptionally suppressed multiple immune response pathways in PBMCs upon stimulation. Our findings indicate that N-BPs modulate the long-lasting effects of BCG vaccination on the cytokine production capacity of innate immune cells.

Transmission of stimulus-induced epigenetic changes through cell division is coupled to continuous transcription factor activity.

Trained immunity, or innate immune memory, has been attributed to the long-term retention of stimulus-induced histone post-translational modifications (PTMs) following clearance of the initial stimulus. Yet, it remains unknown how this epigenetic memory can persist for months in dividing cells given the lack of any known mechanism for stimulus-induced histone PTMs to be directly copied from parent to daughter strand during DNA replication. Here, using time course RNA-seq, ChIP-seq, and infection assays, we find that trained macrophages are transcriptionally, epigenetically, and functionally re-programmed for at least 14 cell divisions after stimulus washout. However, the epigenetic changes observed after multiple rounds of cell division do not result from the self-sustained propagation of stimulus-induced epigenetic changes through cell division. Instead, long-lasting epigenetic differences between trained and non-trained cells are always coupled with changes in transcription factor (TF) activity, emphasizing the central role played by TFs, and gene expression changes more broadly, in driving the transmission of stimulus-induced epigenetic changes across cell divisions.

BCG vaccination impacts the epigenetic landscape of progenitor cells in human bone marrow.

While the Bacille-Calmette-Guérin (BCG) vaccine is used to prevent tuberculosis, it also offers protection against a diverse range of non-mycobacterial infections. However, the underlying protective mechanisms in humans are not yet fully understood. Here, we surveyed at single-cell resolution the gene expression and chromatin landscape of human bone marrow, aspirated before and 90 days after BCG vaccination or placebo administration. We show that BCG vaccination significantly alters both the gene expression and epigenetic profiles of human hematopoietic stem and progenitor cells (HSPCs). Changes in gene expression occur primarily on the most uncommitted stem cells and are reflective of a persistent myeloid bias. In contrast, BCG-induced changes in chromatin accessibility are most prevalent within differentiated progenitor cells at sites influenced by Kruppel-like factor (KLF)/SP and EGR transcription factors (TFs). These TFs are also activated in the most uncommitted stem cells, indicating that activated TFs, which drive persistent changes in HSC gene expression, likely also drive chromatin dynamics appearing within downstream progenitor cells. This perspective contests the prevailing notion that epigenetic modifications linked to innate immune memory transfer directly from stem cells to their differentiated derivatives. Finally, we show that alterations in gene expression and chromatin accessibility in HSPCs due to BCG vaccination were highly correlated (r>0.8) with the IL-1ß secretion capacity of paired PBMCs upon secondary immune challenge. Overall, our findings shed light on BCG vaccination's profound and lasting effects on HSPCs and its influence on innate immune responses.

The epigenetically-encoded memory of the innate immune system.

Stimulation or infection of innate immune cells induces profound epigenetic changes, including the induction of histone modifications and alterations in DNA methylation levels. While some of these changes are rapidly reversible, others appear to be long-lasting, even in mitotic populations, with important functional consequences for the stimulus-experienced cell. Here we discuss the individual contributions of each of the plethora of known epigenetic modifications to the initial transcriptional response to immune activation, their dynamics as cells return to homeostasis, and their contribution to memory of the initial stimulus.

A Qualitative Analysis of Human Error During the DIBH Procedure.

INTRODUCTION: This quality assurance study analyzed human errors that occurred during the radiation treatment delivery of the deep-inspiration breath hold (DIBH) technique at a tertiary cancer centre. The intention is to recommend solutions and system changes that have the potential to decrease the frequency of errors based on human factors principles. METHODS: Eighty-two incident reports from January 2012 to July 2017 were retrieved and analysed to determine theme bins of performance-influencing factors contributing to the error. Performance-influencing factors were generated from the incident reports and from focus group discussions with volunteer radiation therapists in the department. Potential solutions to mitigate the error were sought from incident reports, focus groups, literature search, and an interview with a human factors specialist. The solutions were ranked based on the hierarchy of effectiveness, and recommendations were classified using a priority matrix. RESULTS: Eighty-nine percent of the errors captured in the incident reports were defined as a slip or lapse error type, and 11% of the remaining errors were defined as a mistake error type. Treatment-related problem solving and distractions/interruptions were the highest frequency causative factors that contributed to the observed error. Potential solutions that were suggested across sources included implementing a forcing function, such as the real-time position management system, adding reminders, such as a console sign-off, and updating the current task checklist. DISCUSSION: The potential solutions generated were summarized into four recommendations that have varying degrees of association with known causative factors. The four recommendations include investing in (1) a forcing function, (2) updating/reinforcing the procedure, (3) managing workload, and (4) updating the checklist. A priority matrix was used to assess both potential effectiveness and cost/effort of each recommendation. Ideally, recommendation 1 would be implemented; however, it is understood that there would be an associated cost. It is therefore suggested that recommendations 2, 3, and 4 are implemented together to increase the effectiveness of the intervention until recommendation 1 can be achieved. CONCLUSION: This qualitative study introduced a method that analyzed human factors in a specialized procedure used in the treatment of a specific population of patients with cancer. Recommendations were formulated and proposed to the radiation therapy department in hopes of potentially decreasing the frequency of this specific error in the future.

Plasma membrane localization signals in the light chain of botulinum neurotoxin.

Botulinum neurotoxin (BoNT) is a potent biological substance used to treat neuromuscular and pain disorders. Both BoNT type A and BoNT type E display high-affinity uptake into motor neurons and inhibit exocytosis through cleavage of the synaptosome-associated protein of 25 kDa (SNAP25). The therapeutic effects of BoNT/A last from 3 to 12 months, whereas the effects of BoNT/E last less than 4 weeks. Using confocal microscopy and site-specific mutagenesis, we have determined that the protease domain of BoNT/A light chain (BoNT/A-LC) localizes in a punctate manner to the plasma membrane, colocalizing with the cleaved product, SNAP25(197). In contrast, the short-duration BoNT/E serotype is cytoplasmic. Mutations in the BoNT/A-LC have revealed sequences at the N terminus necessary for plasma membrane localization, and an active dileucine motif in the C terminus that is likely involved in trafficking and interaction with adaptor proteins. These data support sequence-specific signals as determinants of intracellular localization and as a basis for the different durations of action in these two BoNT serotypes.