The transcription factors and pathways underpinning male reproductive development in Arabidopsis.

As Arabidopsis flowers mature, specialized cells within the anthers undergo meiosis, leading to the production of haploid microspores that differentiate into mature pollen grains, each containing two sperm cells for double fertilization. During pollination, the pollen grains are dispersed from the anthers to the stigma for subsequent fertilization. Transcriptomic studies have identified a large number of genes expressed over the course of male reproductive development and subsequent functional characterization of some have revealed their involvement in floral meristem establishment, floral organ growth, sporogenesis, meiosis, microsporogenesis, and pollen maturation. These genes encode a plethora of proteins, ranging from transcriptional regulators to enzymes. This review will focus on the regulatory networks that control male reproductive development, starting from flower development and ending with anther dehiscence, with a focus on transcription factors and some of their notable target genes.

C5aR1 activation in mice controls inflammatory eosinophil recruitment and functions in allergic asthma.

BACKGROUND: Pulmonary eosinophils comprise at least two distinct populations of resident eosinophils (rEOS) and inflammatory eosinophils (iEOS), the latter recruited in response to pulmonary inflammation. Here, we determined the impact of complement activation on rEOS and iEOS trafficking and function in two models of pulmonary inflammation. METHODS: BALB/c wild-type and C5ar1-/- mice were exposed to different allergens or IL-33. Eosinophil populations in the airways, lung, or mediastinal lymph nodes (mLN) were characterized by FACS or immunohistochemistry. rEOS and iEOS functions were determined in vivo and in vitro. RESULTS: HDM and IL-33 exposure induced a strong accumulation of iEOS but not rEOS in the airways, lungs, and mLNs. rEOS and iEOS expressed C3/C5 and C5aR1, which were significantly higher in iEOS. Initial pulmonary trafficking of iEOS was markedly reduced in C5ar1-/- mice and associated with less IL-5 production from ILC2 cells. Functionally, adoptively transferred pulmonary iEOS from WT but not from C5ar1-/- mice-induced airway hyperresponsiveness (AHR), which was associated with significantly reduced C5ar1-/- iEOS degranulation. Pulmonary iEOS but not rEOS were frequently associated with T cells in lung tissue. After HDM or IL-33 exposure, iEOS but not rEOS were found in mLNs, which were significantly reduced in C5ar1-/- mice. C5ar1-/- iEOS expressed less costimulatory molecules, associated with a decreased potency to drive antigen-specific T cell proliferation and differentiation into memory T cells. CONCLUSIONS: We uncovered novel roles for C5aR1 in iEOS trafficking and activation, which affects key aspects of allergic inflammation such as AHR, ILC2, and T cell activation.

Heat stress response mechanisms in pollen development.

Being rooted in place, plants are faced with the challenge of responding to unfavourable local conditions. One such condition, heat stress, contributes massively to crop losses globally. Heatwaves are predicted to increase, and it is of vital importance to generate crops that are tolerant to not only heat stress but also to several other abiotic stresses (e.g. drought stress, salinity stress) to ensure that global food security is protected. A better understanding of the molecular mechanisms that underlie the temperature stress response in pollen will be a significant step towards developing effective breeding strategies for high and stable production in crop plants. While most studies have focused on the vegetative phase of plant growth to understand heat stress tolerance, it is the reproductive phase that requires more attention as it is more sensitive to elevated temperatures. Every phase of reproductive development is affected by environmental challenges, including pollen and ovule development, pollen tube growth, male-female cross-talk, fertilization, and embryo development. In this review we summarize how pollen is affected by heat stress and the molecular mechanisms employed during the stress period, as revealed by classical and -omics experiments.

Infant Feeding Practices During the First Postnatal Year and Risk of Asthma and Allergic Disease During the First 6 Years of Life.

Background: Breastfeeding may protect against childhood asthma and allergic diseases. Studies have not focused on the mode of feeding human milk and followed children to school age although feeding human milk from a bottle rather than the breast may alter the risk of disease. Materials and Methods: At 12 months' postpartum, women in the Moms2Moms study (Columbus, OH) completed a survey assessing sociodemographic and infant feeding behaviors. At 6 years' postpartum, they completed a survey and pediatric medical records were abstracted to assess asthma and allergic disease diagnoses. Logistic regression models were used to estimate associations between infant feeding behaviors and asthma or allergic disease. Results: Of 285 children, 16% had asthma and 44% ever had ≥1 allergy diagnosis. Longer durations of each infant feeding behavior were not clearly associated with increased odds of asthma or allergic disease by age 6. Results suggested that longer durations of breast milk feeding (regardless of the mode of feeding) may be related to a lower risk of food allergy (e.g., odds ratio [OR]1-month, adjusted = 0.96, 95% confidence interval [CI] = 0.87-1.05; OR12-month, adjusted = 0.57, 95% CI = 0.19-1.74), but that the mode of feeding (regardless of the substance fed) may be more meaningful for environmental allergies (e.g., exclusive direct breast milk feeding OR12-month, adjusted = 0.32, 95% CI = 0.06-1.81). However, effect estimates were imprecise and CIs included the null. Conclusions: Although no clear associations between mode of breast milk feeding (breast versus expressed) and asthma and allergy outcomes were observed, future research with larger samples should further evaluate these associations.

Arabidopsis bZIP18 and bZIP52 Accumulate in Nuclei Following Heat Stress where They Regulate the Expression of a Similar Set of Genes.

Heat stress (HS) is a major abiotic stress that negatively impacts crop yields across the globe. Plants respond to elevated temperatures by changing gene expression, mediated by transcription factors (TFs) functioning to enhance HS tolerance. The involvement of Group I bZIP TFs in the heat stress response (HSR) is not known. In this study, bZIP18 and bZIP52 were investigated for their possible role in the HSR. Localization experiments revealed their nuclear accumulation following heat stress, which was found to be triggered by dephosphorylation. Both TFs were found to possess two motifs containing serine residues that are candidates for phosphorylation. These motifs are recognized by 14-3-3 proteins, and bZIP18 and bZIP52 were found to bind 14-3-3 ε, the interaction of which sequesters them to the cytoplasm. Mutation of both residues abolished 14-3-3 ε interaction and led to a strict nuclear localization for both TFs. RNA-seq analysis revealed coordinated downregulation of several metabolic pathways including energy metabolism and translation, and upregulation of numerous lncRNAs in particular. These results support the idea that bZIP18 and bZIP52 are sequestered to the cytoplasm under control conditions, and that heat stress leads to their re-localization to nuclei, where they jointly regulate gene expression.

Lifestyle and Early Achievement in Families (LEAF) study: Design of an ambidirectional cohort study of prenatal marijuana exposure and child development and behaviour.

BACKGROUND: Marijuana is the most-used illicit substance during pregnancy in the USA, but only two cohort studies, begun over 30 years ago, were specifically established to assess the association of pregnancy use with childhood outcomes. They found use to be associated with specific deficits in executive function at 8+ years, but did not focus on these outcomes earlier in life when intervention may be more successful. Two general purpose cohorts found increased aggression in exposed female toddlers and increased behavioural problems and tic disorders in exposed school-age children. OBJECTIVES: The Lifestyle and Early Achievement in Families (LEAF) study assesses the association of in utero marijuana exposure, documented prospectively by biomarker, self-report, and medical records, with executive function and aggression at age 3½-7 years. METHODS: This ambidirectional cohort (historical cohort with continued follow-up) includes women enrolled in the Perinatal Research Repository during prenatal care at Ohio State University Wexner Medical Center and their children, recontacted 3½-7 years post-birth. Children complete 1-2 study visits including cognitive testing, behavioural observation, and maternal and teacher report of behaviour. Family and social environmental factors are assessed. RESULTS: Child follow-up began in September 2016; visits continue through August 2020. There are 362 eligible children; 32% had mothers who used marijuana during pregnancy, 10% of mothers completed college, and 23% did not complete high school. Mean maternal age at study registration in pregnancy was 26.4 years, and 63% of mothers were African American. To date, 268 children have completed at least 1 study visit. CONCLUSIONS: The LEAF Study will document the association of prenatal marijuana exposure with development and behaviour in the current era when marijuana is more potent than when previous cohorts were studied. The results may inform policy and interventions to counsel reproductive-aged women about the risks of use during pregnancy and guide prevention and treatment of adverse effects among children.

To attend, or not to attend: Examining caregiver intentions and study compliance in a pediatric, randomized controlled trial.

BACKGROUND/AIMS: The Intent to Attend is a brief questionnaire recommended by the National Research Council to address dropout concerns and improve prediction of missing data in clinical trials, although implementation has been very limited. As a formative study in pediatric research, the relationship between caregiver intentions and study compliance was investigated in a 180-day trial of dietary supplementation of preterm toddlers. Treatment effect estimation in the context of missing data was also explored. METHODS: Study compliance (i.e. study completion, supplement adherence, and diary completion) was tracked over three study visits. Baseline questionnaires asked caregivers about intentions concerning study completion via the Intent to Attend, screened for mental health symptoms (depression, trait anxiety), and captured family demographics. Simple and multiple logistic regression models were built to examine associations between caregiver intent and compliance outcomes. The Intent to Attend was also employed as an auxiliary variable to account for missing data within mixed models estimating the treatment effect on the primary outcomes. RESULTS: Of the 316 caregiver-child dyads included, 95% of caregivers with low intentions had a child complete the study, but only 87% of caregivers with high intentions had a child complete the study. Low intentions to complete the study were associated with a more than 60% lower odds of study non-completion, but the confidence interval included the null (odds ratio: 0.36; 95% confidence interval: 0.11, 1.20). No effect measure modification by caregiver mental health, child sex, or annual income was detected. Income was the only significant predictor of study non-completion; the lowest income group was almost four times more likely to be study non-completers compared with the highest income group, even after adjustment for child sex and caregiver mental health (adjusted odds ratio = 3.59, 95% confidence interval: 1.38, 9.31). When using Intent to Attend as an auxiliary variable, similar results were obtained when compared with the original treatment effect estimates on the primary outcomes. CONCLUSION: Contrary to prior adult studies, there is no clear relationship between caregiver intentions and study compliance. Findings elucidate the complexities of caregiver-child interactions during pediatric trial participation.

Short-term high-fat diet feeding protects from the development of experimental allergic asthma in mice.

BACKGROUND: A close association between obesity and asthma has been described. The nature of this association remains elusive, especially with respect to allergic asthma. Controversial findings exist regarding the impact of short-term high-fat diet (HFD) feeding on the development of allergic asthma. OBJECTIVE: To delineate the impact of short-term HFD feeding on the development of experimental allergic asthma. METHODS: Female C57BL/6JRJ mice were fed with a short-term HFD or chow diet (CD) for 12 weeks. Allergic asthma was induced by intraperitoneal OVA/alum sensitization followed by repeated OVA airway challenges. We determined airway hyperresponsiveness (AHR) and pulmonary inflammation by histologic and flow cytometric analysis of immune cells. Furthermore, we assessed the impact of HFD on dendritic cell (DC)-mediated activation of T cells. RESULTS: Female mice showed a mild increase in body weight accompanied by mild metabolic alterations. Upon OVA challenge, CD-fed mice developed strong AHR and airway inflammation, which were markedly reduced in HFD-fed mice. Mucus production was similar in both treatment groups. OVA-induced increases in DC and CD4+ T-cell recruitment to the lungs were significantly attenuated in HFD-fed mice. MHC-II expression and CD40 expression in pulmonary CD11b+ DCs were markedly lower in HFD-fed compared to CD-fed mice, which was associated in vivo with a decreased T helper (Th) 1/17 differentiation and Treg formation without impacting Th2 differentiation. CONCLUSIONS/CLINICAL RELEVANCE: These findings suggest that short-term HFD feeding attenuates the development of AHR, airway inflammation, pulmonary DC recruitment and MHC-II/CD40 expression leading to diminished Th1/17 but unchanged Th2 differentiation. Thus, short-term HFD feeding and associated metabolic alterations may have protective effects in allergic asthma development.

C/EBPß regulates the M2 transcriptome in ß-adrenergic-stimulated macrophages.

At the M2 terminal of the macrophage activation spectrum, expression of genes is regulated by transcription factors that include STAT6, CREB, and C/EBPß. Signaling through ß-adrenergic receptors drives M2 activation of macrophages, but little is known about the transcription factors involved. In the present study, we found that C/EBPß regulates the signaling pathway between ß-adrenergic stimulation and expression of Arg1 and several other specific genes in the greater M2 transcriptome. ß-adrenergic signaling induced Cebpb gene expression relatively early with a peak at 1 h post-stimulation, followed by peak Arg1 gene expression at 8 h. C/EBPß transcription factor activity was elevated at the enhancer region for Arg 1 at both 4 and 8 h after stimulation but not near the more proximal promoter region. Knockdown of Cebpb suppressed the ß-adrenergic-induced peak in Cebpb gene expression as well as subsequent accumulation of C/EBPß protein in the nucleus, which resulted in suppression of ß-adrenergic-induced Arg1 gene expression. Analysis of genome-wide transcriptional profiles identified 20 additional M2 genes that followed the same pattern of regulation by ß-adrenergic- and C/EBPß-signaling. Promoter-based bioinformatic analysis confirmed enrichment of binding motifs for C/EBPß transcription factor across these M2 genes. These findings pinpoint a mechanism that may be targeted to redirect the deleterious influence of ß-adrenergic signaling on macrophage involvement in M2-related diseases such as cancer.

Monitoring C5aR2 Expression Using a Floxed tdTomato-C5aR2 Knock-In Mouse.

The biological significance of C5a receptor [(C5aR)2/C5L2], a seven-transmembrane receptor binding C5a and C5adesArg, remains ill-defined. Specific ligation of C5aR2 inhibits C5a-induced ERK1/2 activation, strengthening the view that C5aR2 regulates C5aR1-mediated effector functions. Although C5aR2 and C5aR1 are often coexpressed, a detailed picture of C5aR2 expression in murine cells and tissues is still lacking. To close this gap, we generated a floxed tandem dye (td)Tomato-C5aR2 knock-in mouse that we used to track C5aR2 expression in tissue-residing and circulating immune cells. We found the strongest C5aR2 expression in the brain, bone marrow, and airways. All myeloid-derived cells expressed C5aR2, although with different intensities. C5aR2 expression in blood and tissue neutrophils was strong and homogeneous. Specific ligation of C5aR2 in neutrophils from tdTomato-C5aR2 mice blocked C5a-driven ERK1/2 phosphorylation, demonstrating functionality of C5aR2 in the reporter mice. In contrast to neutrophils, we found tissue-specific differences in C5aR2 expression in eosinophils, macrophages, and dendritic cell subsets. Naive and activated T cells stained negative for C5aR2, whereas B cells from different tissues homogeneously expressed C5aR2. Also, NK cell subsets in blood and spleen strongly expressed C5aR2. Activation of C5aR2 in NK cells suppressed IL-12/IL-18-induced IFN-γ production. Intratracheal IL-33 challenge resulted in decreased C5aR2 expression in pulmonary eosinophils and monocyte-derived dendritic cells. In summary, we provide a detailed map of murine C5aR2 immune cell expression in different tissues under steady-state conditions and upon pulmonary inflammation. The C5aR2 knock-in mouse will help to reliably track and conditionally delete C5aR2 expression in experimental models of inflammation.

The C5a/C5aR1 axis controls the development of experimental allergic asthma independent of LysM-expressing pulmonary immune cells.

C5a regulates the development of maladaptive immune responses in allergic asthma mainly through the activation of C5a receptor 1 (C5aR1). Yet, the cell types and the mechanisms underlying this regulation are ill-defined. Recently, we described increased C5aR1 expression in lung tissue eosinophils but decreased expression in airway and pulmonary macrophages as well as in pulmonary CD11b+ conventional dendritic cells (cDCs) and monocyte-derived DCs (moDCs) during the allergic effector phase using a floxed green fluorescent protein (GFP)-C5aR1 knock-in mouse. Here, we determined the role of C5aR1 signaling in neutrophils, moDCs and macrophages for the pulmonary recruitment of such cells and the importance of C5aR1-mediated activation of LysM-expressing cells for the development of allergic asthma. We used LysM-C5aR1 KO mice with a specific deletion of C5aR1 in LysMCre-expressing cells and confirmed the specific deletion of C5aR1 in neutrophils, macrophages and moDCs in the airways and/or the lung tissue. We found that alveolar macrophage numbers were significantly increased in LysM-C5aR1 KO mice. Induction of ovalbumin (OVA)-driven experimental allergic asthma in GFP-C5aR1fl/fl and LysM-C5aR1 KO mice resulted in strong but similar airway resistance, mucus production and Th2/Th17 cytokine production. In contrast, the number of airway but not of pulmonary neutrophils was lower in LysM-C5aR1 KO as compared with GFP-C5aR1fl/fl mice. The recruitment of macrophages, cDCs, moDCs, T cells and type 2 innate lymphoid cells was not altered in LysM-C5aR1 KO mice. Our findings demonstrate that C5aR1 is critical for steady state control of alveolar macrophage numbers and the transition of neutrophils from the lung into the airways in OVA-driven allergic asthma. However, C5aR1 activation of LysM-expressing cells plays a surprisingly minor role in the recruitment and activation of such cells and the development of the allergic phenotype in OVA-driven experimental allergic asthma.

Monitoring C3aR Expression Using a Floxed tdTomato-C3aR Reporter Knock-in Mouse.

C3a exerts multiple biologic functions through activation of its cognate C3a receptor. C3-/- and C3aR-/- mice have been instrumental in defining important roles of the C3a/C3aR axis in the regulation of acute and chronic inflammatory diseases, including ischemia/reperfusion injury, allergic asthma, autoimmune nephritis, and rheumatoid arthritis. Surprisingly little is known about C3aR expression and function in immune and stromal cells. To close this gap, we generated a floxed tandem-dye Tomato (tdTomato)-C3aR reporter knock-in mouse, which we used to monitor C3aR expression in cells residing in the lung, airways, lamina propria (LP) of the small intestine, brain, visceral adipose tissue, bone marrow (BM), spleen, and the circulation. We found a strong expression of tdTomato-C3aR in the brain, lung, LP, and visceral adipose tissue, whereas it was minor in the spleen, blood, BM, and the airways. Most macrophage and eosinophil populations were tdTomato-C3aR+ Interestingly, most tissue eosinophils and some macrophage populations expressed C3aR intracellularly. BM-derived dendritic cells (DCs), lung-resident cluster of differentiation (CD) 11b+ conventional DCs (cDCs) and monocyte-derived DCs, LP CD103+, and CD11b+ cDCs but not pulmonary CD103+ cDCs and splenic DCs were tdTomato-C3aR+ Surprisingly, neither BM, blood, lung neutrophils, nor mast cells expressed C3aR. Similarly, all lymphoid-derived cells were tdTomato-C3aR-, except some LP-derived type 3 innate lymphoid cells. Pulmonary and LP-derived epithelial cells expressed at best minor levels of C3aR. In summary, we provide novel insights into the expression pattern of C3aR in mice. The floxed C3aR knock-in mouse will help to reliably track and conditionally delete C3aR expression in experimental models of inflammation.

Differential regulation of C5a receptor 1 in innate immune cells during the allergic asthma effector phase.

C5a drives airway constriction and inflammation during the effector phase of allergic asthma, mainly through the activation of C5a receptor 1 (C5aR1). Yet, C5aR1 expression on myeloid and lymphoid cells during the allergic effector phase is ill-defined. Recently, we generated and characterized a floxed green fluorescent protein (GFP)-C5aR1 knock-in mouse. Here, we used this reporter strain to monitor C5aR1 expression in airway, pulmonary and lymph node cells during the effector phase of OVA-driven allergic asthma. C5aR1 reporter and wildtype mice developed a similar allergic phenotype with comparable airway resistance, mucus production, eosinophilic/neutrophilic airway inflammation and Th2/Th17 cytokine production. During the allergic effector phase, C5aR1 expression increased in lung tissue eosinophils but decreased in airway and pulmonary macrophages as well as in pulmonary CD11b+ conventional dendritic cells (cDCs) and monocyte-derived DCs (moDCs). Surprisingly, expression in neutrophils was not affected. Of note, moDCs but not CD11b+ cDCs from mediastinal lymph nodes (mLN) expressed less C5aR1 than DCs residing in the lung after OVA challenge. Finally, neither CD103+ cDCs nor cells of the lymphoid lineage such as Th2 or Th17-differentiated CD4+ T cells, B cells or type 2 innate lymphoid cells (ILC2) expressed C5aR1 under allergic conditions. Our findings demonstrate a complex regulation pattern of C5aR1 in the airways, lung tissue and mLN of mice, suggesting that the C5a/C5aR1 axis controls airway constriction and inflammation through activation of myeloid cells in all three compartments in an experimental model of allergic asthma.

Regulation and function of anaphylatoxins and their receptors in allergic asthma.

Allergic asthma is a disease of the airways driven by maladaptive T helper 2 (Th2) and Th17 immune response against harmless, airborne substances. The hallmarks of this disease are airway hyperresponsiveness (AHR), eosinophilic and neutrophilic airway inflammation and mucus overproduction. Distinct dendric cell (DC) subsets together with airway epithelial and pulmonary vascular endothelial cells play critical roles in allergen sensing and in driving T cell differentiation towards Th2 and Th17 effector or regulatory T cells (Treg). Previous studies suggested already a pivotal role for the anaphylatoxins (C5a, C3a) in the pathogenesis of allergic asthma. During sensitization for example it is described, that C3a promotes, whereas C5a protects from the development of maladaptive immunity during allergen sensitization. Here we will discuss the role of the anaphylatoxins (C3a, C5a) and their receptors during the pathogenesis of allergic asthma, and specifically in lung DC biology. We will also have a look on canonical and non-canonical complement activation and we will discuss novel concepts on how the adaptive immune system can regulate the function of ATRs also in the context of allergic asthma.

Distinct roles of the anaphylatoxins C3a and C5a in dendritic cell-mediated allergic asthma.

Conventional dendritic cells (cDC) are necessary and sufficient to drive mixed maladaptive Th2/Th17 immune responses toward aeroallergens in experimental allergy models. Previous studies suggest that the anaphylatoxin C3a promotes, whereas C5a protects from the development of maladaptive immunity during allergen sensitization. However, only limited evidence exists that such effects are directly mediated through anaphylatoxin-receptor signaling in cDCs. In this study, we assessed the impact of C3a and C5a on cDC-mediated induction pulmonary allergy by adoptively transferring house dust mite (HDM)-pulsed bone marrow-derived DCs (BMDC) from wild-type (WT) C3aR(-/-), C5aR1(-/-), or C3aR(-/-)/C5aR1(-/-) into WT mice. Transfer of HDM-pulsed WT BMDCs promoted a strong asthmatic phenotype characterized by marked airway resistance, strong Th2 cytokine, and mucus production, as well as mixed eosinophilic and neurophilic airway inflammation. Surprisingly, C3aR(-/-) cDCs induced a strong allergic phenotype, but no IL-17A production, whereas HDM-pulsed C5aR1(-/-) cDCs failed to drive pulmonary allergy. Transfer of C3aR(-/-)/C5aR1(-/-) cDCs resulted in a slightly reduced allergic phenotype associated with increased IFN-γ production. Mechanistically, C3aR and C5aR1 signaling is required for IL-23 production from HDM-pulsed BMDCs in vitro. Furthermore, C3aR(-/-) BMDCs produced less IL-1ß. The mechanisms underlying the failure of C5aR1(-/-) BMDCs to induce experimental allergy include a reduced capability to migrate into the lung tissue and a decreased potency to direct pulmonary homing of effector T cells. Thus, we uncovered a crucial role for C5a, but only a minor role for C3a in BMDC-mediated pulmonary allergy, suggesting that BMDCs inappropriately reflect the impact of complement on lung cDC-mediated allergic asthma development.

The plant growth promoting substance, lumichrome, mimics starch, and ethylene-associated symbiotic responses in lotus and tomato roots.

Symbiosis involves responses that maintain the plant host and symbiotic partner's genetic program; yet these cues are far from elucidated. Here we describe the effects of lumichrome, a flavin identified from Rhizobium spp., applied to lotus (Lotus japonicus) and tomato (Solanum lycopersicum). Combined transcriptional and metabolite analyses suggest that both species shared common pathways that were altered in response to this application under replete, sterile conditions. These included genes involved in symbiosis, as well as transcriptional and metabolic responses related to enhanced starch accumulation and altered ethylene metabolism. Lumichrome priming also resulted in altered colonization with either Mesorhizobium loti (for lotus) or Glomus intraradices/G. mossea (for tomato). It enhanced nodule number but not nodule formation in lotus; while leading to enhanced hyphae initiation and delayed arbuscule maturation in tomato.