Targeting SELPLG/P-selectin glycoprotein ligand 1 in preclinical ARDS: Genetic and epigenetic regulation of the SELPLG promoter

We previously identified a missense single nucleotide polymorphism rs2228315 (G>A, Met62Ile) in the selectin-P-ligand gene (SELPLG), encoding P-selectin glycoprotein ligand 1 (PSGL-1), to be associated with increased susceptibility to acute respiratory distress syndrome (ARDS). These earlier studies demonstrated that SELPLG lung tissue expression was increased in mice exposed to lipopolysaccharide (LPS)- and ventilator-induced lung injury (VILI) suggesting that inflammatory and epigenetic factors regulate SELPLG promoter activity and transcription. In this report, we used a novel recombinant tandem PSGL1 immunoglobulin fusion molecule (TSGL-Ig), a competitive inhibitor of PSGL1/P-selectin interactions, to demonstrate significant TSGL-Ig-mediated decreases in SELPLG lung tissue expression as well as highly significant protection from LPS- and VILI-induced lung injury. In vitro studies examined the effects of key ARDS stimuli (LPS, 18% cyclic stretch to simulate VILI) on SELPLG promoter activity and showed LPS-mediated increases in SELPLG promoter activity and identified putative promoter regions associated with increased SELPLG expression. SELPLG promoter activity was strongly regulated by the key hypoxia-inducible transcription factors, HIF-1α, and HIF-2α as well as NRF2. Finally, the transcriptional regulation of SELPLG promoter by ARDS stimuli and the effect of DNA methylation on SELPLG expression in endothelial cell was confirmed. These findings indicate SELPLG transcriptional regulation by clinically-relevant inflammatory factors with the significant TSGL-Ig-mediated attenuation of LPS and VILI highly consistent with PSGL1/P-selectin as therapeutic targets in ARDS.

eNAMPT Neutralization Preserves Lung Fluid Balance and Reduces Acute Renal Injury in Porcine Sepsis/VILI-Induced Inflammatory Lung Injury

Background: Numerous potential ARDS therapeutics, based upon preclinical successful rodent studies that utilized LPS challenge without mechanical ventilation, have failed in Phase 2/3 clinical trials. Recently, ALT-100 mAb, a novel biologic that neutralizes the TLR4 ligand and DAMP, eNAMPT (extracellular nicotinamide phosphoribosyltransferase), was shown to reduce septic shock/VILI-induced porcine lung injury when delivered 2 h after injury onset. We now examine the ALT-100 mAb efficacy on acute kidney injury (AKI) and lung fluid balance in a porcine ARDS/VILI model when delivered 6 h post injury.

Methods/Results: Compared to control PBS-treated pigs, exposure of ALT-100 mAb-treated pigs (0.4 mg/kg, 2 h or 6 h after injury initiation) to LPS-induced pneumonia/septic shock and VILI (12 h), demonstrated significantly diminished lung injury severity (histology, BAL PMNs, plasma cytokines), biochemical/genomic evidence of NF-kB/MAP kinase/cytokine receptor signaling, and AKI (histology, plasma lipocalin). ALT-100 mAb treatment effectively preserved lung fluid balance reflected by reduced BAL protein/tissue albumin levels, lung wet/dry tissue ratios, ultrasound-derived B lines, and chest radiograph opacities. Delayed ALT-100 mAb at 2 h was significantly more protective than 6 h delivery only for plasma eNAMPT while trending toward greater protection for remaining inflammatory indices. Delayed ALT-100 treatment also decreased lung/renal injury indices in LPS/VILI-exposed rats when delivered up to 12 h after LPS.

Conclusions: These studies indicate the delayed delivery of the eNAMPT-neutralizing ALT-100 mAb reduces inflammatory lung injury, preserves lung fluid balance, and reduces multi-organ dysfunction, and may potentially address the unmet need for novel therapeutics that reduce ARDS/VILI mortality.

eNAMPT neutralization reduces preclinical ARDS severity via rectified NFkB and Akt/mTORC2 signaling

Despite encouraging preclinical data, therapies to reduce ARDS mortality remains a globally unmet need, including during the COVID-19 pandemic. We previously identified extracellular nicotinamide phosphoribosyltransferase (eNAMPT) as a novel damage-associated molecular pattern protein (DAMP) via TLR4 ligation which regulates inflammatory cascade activation. eNAMPT is tightly linked to human ARDS by biomarker and genotyping studies in ARDS subjects. We now hypothesize that an eNAMPT-neutralizing mAb will significantly reduce the severity of ARDS lung inflammatory lung injury in diverse preclinical rat and porcine models. Sprague Dawley rats received eNAMPT mAb intravenously following exposure to intratracheal lipopolysaccharide (LPS) or to a traumatic blast (125 kPa) but prior to initiation of ventilator-induced lung injury (VILI) (4 h). Yucatan minipigs received intravenous eNAMPT mAb 2 h after initiation of septic shock and VILI (12 h). Each rat/porcine ARDS/VILI model was strongly associated with evidence of severe inflammatory lung injury with NFkB pathway activation and marked dysregulation of the Akt/mTORC2 signaling pathway. eNAMPT neutralization dramatically reduced inflammatory indices and the severity of lung injury in each rat/porcine ARDS/VILI model (~ 50% reduction) including reduction in serum lactate, and plasma levels of eNAMPT, IL-6, TNFα and Ang-2. The eNAMPT mAb further rectified NFkB pathway activation and preserved the Akt/mTORC2 signaling pathway. These results strongly support targeting the eNAMPT/TLR4 inflammatory pathway as a potential ARDS strategy to reduce inflammatory lung injury and ARDS mortality.

Major locus for spontaneous haploid genome doubling detected by a case-control GWAS in exotic maize germplasm

A major locus for spontaneous haploid genome doubling was detected by a case-control GWAS in an exotic maize germplasm. The combination of double haploid breeding method with this locus leads to segregation distortion on genomic regions of chromosome five. Temperate maize (Zea mays L.) breeding programs often rely on limited genetic diversity, which can be expanded by incorporating exotic germplasm. The aims of this study were to perform characterization of inbred lines derived from the tropical BS39 population using different breeding methods, to identify genomic regions showing segregation distortion in lines derived by the DH process using spontaneous haploid genome doubling (SHGD), and use case-control association mapping to identify loci controlling SHGD. Four different sets were used: BS39_DH and BS39_SSD were derived from the BS39 population by DH and single-seed descendent (SSD) methods, and BS39 × A427_DH and BS39 × A427_SSD from the cross between BS39 and A427. A total of 663 inbred lines were genotyped. The analyses of gene diversity and genetic differentiation for the DH sets provided evidence of the presence of a SHGD locus near the centromere of chromosome 5. The case-control GWAS for the DH set also pinpointed this locus. Haplotype sharing analysis showed almost 100% exclusive contribution of the A427 genome in the same region on chromosome 5 of BS39 × A427_DH, presumably due to an allele in this region affecting SHGD. This locus enables DH line production in exotic populations without colchicine or other artificial haploid genome doubling.

Technological advances in maize breeding: past, present and future

Maize has for many decades been both one of the most important crops worldwide and one of the primary genetic model organisms. More recently, maize breeding has been impacted by rapid technological advances in sequencing and genotyping technology, transformation including genome editing, doubled haploid technology, parallelled by progress in data sciences and the development of novel breeding approaches utilizing genomic information. Herein, we report on past, current and future developments relevant for maize breeding with regard to (1) genome analysis, (2) germplasm diversity characterization and utilization, (3) manipulation of genetic diversity by transformation and genome editing, (4) inbred line development and hybrid seed production, (5) understanding and prediction of hybrid performance, (6) breeding methodology and (7) synthesis of opportunities and challenges for future maize breeding.

The ETS family transcription factors ETV5 and PU.1 co-regulate Th9 cell differentiation (HYP2P.334)

T helper 9 (Th9) cells, a CD4+ T cell subset characterized by their robust production of interleukin (IL)-9, can promote allergic inflammation in mice and are associated with atopic disease in humans. We have previously demonstrated that the E26 transformation-specific (ETS)-family transcription factor PU.1 is integral in Th9 mediated IL-9 production and is the only transcription factor, to date, that induces IL-9 production in another Th subset. Because conditional PU.1 deletion in T cells does not completely eliminate Th9 mediated IL-9 production, we investigated whether other ETS proteins were important transcription factors in Th9 cell development. Herein, we demonstrate that ectopic expression of ETS Variant 5 (ETV5) can also enhance Th9 cell differentiation and promote IL-9 production in Th2 differentiated cells. Conversely, conditional deletion of ETV5 impaired IL-9 production in Th9 cultures while promoting Th2 cytokine production. Unlike PU.1 that binds the Il9 promoter, ETV5 preferentially binds potential enhancer regions of Il9, and recruits distinct histone acetyltransferases from those recruited by PU.1. Finally, conditional deficiencies of both ETV5 and PU.1 in T cells effectively eliminated IL-9 production in Th9 cultured cells. The effects of deficiency in both factors are being tested in a model of allergic pulmonary inflammation. Collectively, these data indicate ETV5 and PU.1 co-regulate Th9 cell differentiation in partially non-redundant mechanisms.

T helper 9 (Th9) cellular proliferation and cytokine production is regulated by cAMP responsive element modulator (Crem) (HYP7P.289)

Th9 cells, a CD4+ T cell subset characterized by their robust production of interleukin (IL)-9, can promote allergic inflammation in mice and are associated with atopic disease in humans. Because it might provide targets for therapeutic intervention, it is important to understand the molecular controls governing overall Th9 development and their subsequent effector function. To understand the Th9 transcriptional profile, we recently performed microarray analysis to highlight gene expression enriched in Th9 cells compared to other Th subsets. Crem, which expresses a basic leucine zip domain protein with roles in activating and repressing genes, was among a number of genes with increased expression in Th9 cells. Analysis of mRNA and protein expression among in vitro differentiated Th subsets confirmed Crem was enriched in Th9 cells compared to other subsets. Interestingly, ectopic expression of Crem in Th9 cells repressed their capacity to produce IL-9 upon CD3 re-stimulation while promoting overall cellular proliferation. Crem ectopic expression also promoted cellular expansion in other cultured Th subsets. Conversely, acute siRNA knockdown of Crem mRNA in Th9 differentiated cells resulted in reduced cellular proliferation and enhanced IL-9 production upon CD3 restimulation. Therefore, Crem potentially serves a role in modifying Th9 effector activities upon T cell receptor signaling during allergic disease.

CD86-dependent FoxP3+ regulatory T cells promote resolution of disease after influenza virus infection (IRC4P.492)

Influenza A virus (IAV) infection in the respiratory tract triggers a robust immune response, resulting in both virus clearance and lung inflammation and injury. After virus clearance, resolution of lung disease occurs during a distinct recovery period. The costimulatory molecule CD86 can modulate T cell activity during the initiation and effector stages of the host response to IAV infection, but the role of CD86 during recovery is unknown. We found that antibody-mediated CD86 blockade after virus clearance led to a delay in recovery, characterized by increased numbers of lung neutrophils and innate cytokines in the bronchial alveolar lavage fluid (BAL), but no change in conventional IAV-specific T cell responses. However, CD86 blockade led to decreased numbers of FoxP3+ regulatory T cells (Tregs), and adoptive transfer of Tregs into α-CD86 treated mice rescued the effect of the blockade, supporting a role for Tregs in promoting recovery after virus clearance. Direct depletion of Tregs late after infection using DEREG mice mimicked the CD86 blockade phenotype, confirming a role for Tregs during recovery after virus clearance. Finally, we identified neutrophils as a target of Treg suppression, since neutrophil depletion in Treg-depleted DEREG mice reduced excess BAL cytokines. These results show that CD86-dependent Tregs contribute to the resolution of disease after IAV infection, in part by suppressing neutrophil-driven cytokine release into the airways.

The costimulatory ligand CD86 promotes resolution of disease after influenza virus infection (P6202)

Influenza A virus (IAV) infection can produce severe pulmonary inflammation and injury. The host immune response to infection mediates virus clearance but also contributes to pulmonary inflammation and injury, marking the immune response as a potential therapeutic target after severe infections. Host factors mediating IAV clearance and lung inflammation are well-studied, however, factors controlling recovery from disease following IAV clearance are ill-defined. The costimulatory ligand CD86 mediates interactions between immune cells via its receptors CD28 and CTLA-4. We observed in infected mice that blockade of CD86 signaling in vivo after IAV clearance delays recovery and promotes accumulation of neutrophils in the respiratory tract. Furthermore, CD86 blockade reduces both IL-2 and T regulatory cells (Treg) in the lungs. Depletion of Tregs using DREG mice or Treg depleting antibody after IAV clearance also delays recovery and leads to pulmonary neutrophilia. These data suggest that Tregs may play a crucial role in regulating pulmonary inflammation after IAV infection and are in turn dependent on CD86 ligand engagement. We are continuing to explore the role of CD86 in recovery and resolution of inflammation after IAV infection with the long-term goal of exploring the therapeutic potential of optimizing CD86 signaling to promote Treg function in recovery from infection.

CD8+ T cell effector activity is localized within the pulmonary interstititum, not the airspaces, during influenza infection (92.9)

CD8+ cytolytic T lymphocytes (CTLs) play a crucial role in the resolution of respiratory viral infections through their ability to eliminate infected cells and to release potent anti-viral cytokines. In the influenza viral model, CD8+ CTL effector activity is believed to be focused on respiratory epithelial cells, since these cells are the principal cell types supporting influenza replication. Utilizing the prototypical T cell anti-viral cytokine, IFNγ, as a measure of CD8+ CTL effector activity, we evaluated the tempo of the CD8+ CTL response to influenza infection in vivo in two compartments, the airways overlying the respiratory epithelium and the infected lung interstitium. Surprisingly, CD8+ CTL effector activity was localized not to the respiratory epithelium but within the pulmonary interstitium. We were able to establish, utilizing bone marrow chimeric mice, that infiltrating inflammatory cells of hematopoietic origin were the primary stimulus of CD8+ CTL effector activity. Additionally, we further demonstrated that lung resident CD11c+ cells, likely macrophages and/or dendritic cells, were triggering CD8+ CTL anti-viral activity. These observations suggest that inflammatory mononuclear cells are serving as the primary antigen presenting cells for effector CD8+ CTLs responding within the lungs to infection. CD8+ CTL recognition of infected respiratory epithelial cells appears to serve only a secondary role in orchestrating the pro-inflammatory T cell response.

Antigen persistence and the control of local T cell memory by migrant respiratory dendritic cells following acute virus infection (92.11)

Acute viral infections induce robust adaptive immune responses resulting in virus clearance. Recent evidence suggests that there may be depots of viral antigen which persist in draining lymph nodes following virus clearance and could therefore affect the adaptive immune response and memory formation. The nature of these residual antigen depots, the mechanism of antigen persistence and impact of the persistent antigen on memory T cells remains ill-defined. Employing a murine model of influenza virus infection of the respiratory tract, we have identified respiratory dendritic cells (RDC) as an essential cell responsible for both sampling and presenting residual viral antigen. RDC in the previously infected lung capture residual viral antigen deposited in an irradiation resistant cell type(s) and transport the viral antigen to the local lymph nodes draining the site of infection where the migrant RDC present the antigen to T cells. Furthermore, we demonstrate that there is preferential localization of memory T cells to the DLN following virus clearance as a consequence of presentation of residual viral antigen by the migrant RDC to T cells in the DLN. This enriched population of antigen-specific T cells maintained in the antigen draining LN would likely provide a more rapid and robust recall T cell response to a re-infection.

PLAB, a novel placental bone morphogenetic protein

Bone morphogenetic proteins (BMP) constitute a sub-group of the large transforming growth factor-beta (TGF-beta) family. They play important roles in the embryonic development of multiple structures and in adult bone modeling. We have recently isolated a novel member of the BMP family from placenta, termed PLAB. PLAB is expressed highly in placenta, but can be found upon stringent analysis in low levels in most other tissues. At the amino acid level, PLAB is most closely related to BMP-8/OP-2, another member of the BMP family. Like TGF-beta, PLAB inhibits the proliferation of primitive hematopoietic progenitors. The high expression of PLAB by placenta raises the possibility that it may be a mediator of placental control of embryonic development.

Remember that? A comparison of real-time versus retrospective recall of smoking lapses

Research and treatment assessments often rely on retrospective recall of events. The accuracy of recall was tested using accounts of smoking lapse episodes from 127 participants who had quit smoking, and lapses and temptations were recorded in near-real time using a hand-held computer. These computer records were compared with retrospective accounts elicited 12 weeks later, with a focus on recall of lapses in 4 content domains: mood, activity, episode Triggers, and abstinence violation effects. Recall of lapses was quite poor: Average kappas for items ranged from 0.18 to 0.27. Mean profile rs assessing recall for the overall pattern of behavior were .36, .30, .33, and .44 for these domains, respectively. In recall, participants overestimated their negative affect and the number of cigarettes they had smoked during the lapse, and their recall was influenced by current smoking status. The findings suggest caution in the use of recall in research and intervention.