Microglia play critical roles in brain development, homeostasis, and neurological disorders. Here, we report that human microglial-like cells (iMGLs) can be differentiated from iPSCs to study their ...function in neurological diseases, like Alzheimer’s disease (AD). We find that iMGLs develop in vitro similarly to microglia in vivo, and whole-transcriptome analysis demonstrates that they are highly similar to cultured adult and fetal human microglia. Functional assessment of iMGLs reveals that they secrete cytokines in response to inflammatory stimuli, migrate and undergo calcium transients, and robustly phagocytose CNS substrates. iMGLs were used to examine the effects of Aβ fibrils and brain-derived tau oligomers on AD-related gene expression and to interrogate mechanisms involved in synaptic pruning. Furthermore, iMGLs transplanted into transgenic mice and human brain organoids resemble microglia in vivo. Together, these findings demonstrate that iMGLs can be used to study microglial function, providing important new insight into human neurological disease.
•Fully defined and efficient generation of human microglial-like cells from iPSCs•Whole-transcriptome and functional validation of iPSC-derived microglia (iMGLs)•Novel in vitro and in vivo applications for studying neurological diseases•iMGLs can be used to interrogate AD gene function
Abud et al. describe a fully defined protocol for the generation of human iPSC-derived microglia-like cells (iMGLs). Whole-transcriptome and novel functional analyses were used to validate microglial identity. iMGLs provide a platform for studying microglial function in health and disease.
The discovery of TREM2 as a myeloid-specific Alzheimer's disease (AD) risk gene has accelerated research into the role of microglia in AD. While TREM2 mouse models have provided critical insight, the ...normal and disease-associated functions of TREM2 in human microglia remain unclear. To examine this question, we profile microglia differentiated from isogenic, CRISPR-modified TREM2-knockout induced pluripotent stem cell (iPSC) lines. By combining transcriptomic and functional analyses with a chimeric AD mouse model, we find that TREM2 deletion reduces microglial survival, impairs phagocytosis of key substrates including APOE, and inhibits SDF-1α/CXCR4-mediated chemotaxis, culminating in an impaired response to beta-amyloid plaques in vivo. Single-cell sequencing of xenotransplanted human microglia further highlights a loss of disease-associated microglial (DAM) responses in human TREM2 knockout microglia that we validate by flow cytometry and immunohistochemistry. Taken together, these studies reveal both conserved and novel aspects of human TREM2 biology that likely play critical roles in the development and progression of AD.
In systems alternating between sexual and asexual reproduction, sex increases under unfavorable environmental conditions. In plants producing sexual and asexual (apomictic) seeds, studies on the ...influence of environmental factors on sex are equivocal. We used Paspalum intermedium to study environmental effects on the expression of sexual and apomictic developments, and on resulting reproductive fitness variables. Flow cytometric and embryological analyses were performed to characterize ploidy and reproductive modes, and effects of local climatic conditions on sexual and apomictic ovule and seed frequencies were determined. Seed set and germination data were collected and used to estimate reproductive fitness. Frequencies of sexual and apomictic ovules and seeds were highly variable within and among populations. Apomictic development exhibited higher competitive ability but lower overall fitness. Frequencies of sexual reproduction in facultative apomictic plants increased at lower temperatures and wider mean diurnal temperature ranges. We identified a two-fold higher fitness advantage of sexuality and a Tug of War between factors intrinsic to apomixis and environmental stressors promoting sexuality which influence the distribution of sex in apomictic populations. This points toward a crucial role of local ecological conditions in promoting a reshuffling of genetic variability that may be shaping the adaptative landscape in apomictic P. intermedium plants.
Coxiella burnetii is the agent of the emerging zoonosis Q fever. This pathogen invades phagocytic and non-phagocytic cells and uses a Dot/Icm secretion system to co-opt the endocytic pathway for the ...biogenesis of an acidic parasitophorous vacuole where Coxiella replicates in large numbers. The study of the cell biology of Coxiella infections has been severely hampered by the obligate intracellular nature of this microbe, and Coxiella factors involved in host/pathogen interactions remain to date largely uncharacterized. Here we focus on the large-scale identification of Coxiella virulence determinants using transposon mutagenesis coupled to high-content multi-phenotypic screening. We have isolated over 3000 Coxiella mutants, 1082 of which have been sequenced, annotated and screened. We have identified bacterial factors that regulate key steps of Coxiella infections: 1) internalization within host cells, 2) vacuole biogenesis/intracellular replication, and 3) protection of infected cells from apoptosis. Among these, we have investigated the role of Dot/Icm core proteins, determined the role of candidate Coxiella Dot/Icm substrates previously identified in silico and identified additional factors that play a relevant role in Coxiella pathogenesis. Importantly, we have identified CBU_1260 (OmpA) as the first Coxiella invasin. Mutations in ompA strongly decreased Coxiella internalization and replication within host cells; OmpA-coated beads adhered to and were internalized by non-phagocytic cells and the ectopic expression of OmpA in E. coli triggered its internalization within cells. Importantly, Coxiella internalization was efficiently inhibited by pretreating host cells with purified OmpA or by incubating Coxiella with a specific anti-OmpA antibody prior to host cell infection, suggesting the presence of a cognate receptor at the surface of host cells. In summary, we have developed multi-phenotypic assays for the study of host/pathogen interactions. By applying our methods to Coxiella burnetii, we have identified the first Coxiella protein involved in host cell invasion.
The osteopathic tenets may serve as a useful guideline for an interprofessional program. There is an alignment between the osteopathic tenets and the concept of interprofessional education (IPE). IPE ...occurs when students from two or more professions work with each other to collaborate or improve healthcare outcomes. Holistic treatment is fundamental in both instances, and the interrelatedness of structure and function requires acknowledgment of all healthcare professionals' roles in treating a patient. IPE allows students to gain a better understanding of their own professional roles and the roles of their fellow healthcare providers in treating patients more effectively.
The objectives of this analysis are to evaluate the ability of an interprofessional summer workshop/lecture utilizing an osteopathic focus to educate students from different healthcare colleges about the interconnectedness of the systems of the human body and how working with a team-based approach will ultimately benefit their collective patients. A secondary objective was to determine the students' perceptions before and after the lecture/workshop to see if there were any perceived differences among students in different healthcare professions at either time.
This was a retrospective data analysis conducted on pretest/posttest surveys completed by 73 incoming students from six different healthcare colleges participating in the Summer Preparedness and Readiness Course (SPaRC), held annually at Western University of Health Sciences (WUHS) in Pomona, California. Analysis was conducted on responses collected during the SPaRC programs of 2013, 2016, and 2019. Participants were given surveys containing five questions scored on a five-point Likert scale. The surveys were given before and after an integrated lecture/hands-on workshop presented at SPaRC that reviewed multiple studies showing the utility of connecting the healthcare professions to best treat a patient.
A total of 73 students responded to both the prelecture and postlecture surveys. When the number of positive scores were totaled from students from all colleges, there was an increase in positive responses from 190 (52.2 %) in prelecture surveys when compared to 336 (92.3 %) in postlecture surveys. A Wilcoxon signed-rank test suggested that the lecture workshop elicited a significant improvement in scores from prelecture to postlecture for all students (Z=-6.976, p=0.000). Median scores improved from 3.60 at baseline to 4.40 after the lecture/workshop. Secondary analysis conducted utilizing Kruskal-Wallis H to examine the differences between the responses of the different colleges prelecture and postlecture showed no significant differences prelecture (H 6=7.58, p=0.271) and a significant difference between postlecture answers (H 6=14.04, p=0.029). A series of post hoc independent Kruskal-Wallis H analyses was conducted to identify where differences were, and the only identifiable difference after Bonferroni corrections was between students from the Doctor of Osteopathic Medicine college and the Physician Assistant's college after the lecture/survey (p=0.041).
An interprofessional program with the osteopathic principles of focusing on body unity and relatedness of structure and function may serve as a helpful tool for uniting healthcare professionals in their ultimate goal of better serving their patients.
Dengue: a continuing global threat Guzman, Maria G; Halstead, Scott B; Artsob, Harvey ...
Nature reviews. Microbiology,
12/2010, Volume:
8, Issue:
12 Suppl
Journal Article
Peer reviewed
Open access
Dengue fever and dengue haemorrhagic fever are important arthropod-borne viral diseases. Each year, there are ∼50 million dengue infections and ∼500,000 individuals are hospitalized with dengue ...haemorrhagic fever, mainly in Southeast Asia, the Pacific and the Americas. Illness is produced by any of the four dengue virus serotypes. A global strategy aimed at increasing the capacity for surveillance and outbreak response, changing behaviours and reducing the disease burden using integrated vector management in conjunction with early and accurate diagnosis has been advocated. Antiviral drugs and vaccines that are currently under development could also make an important contribution to dengue control in the future.
Abstract
Developmental exposure to environmental factors has been linked to obesity risk later in life. Nuclear receptors are molecular sensors that play critical roles during development and, as ...such, are prime candidates to explain the developmental programming of disease risk by environmental chemicals. We have previously characterized the obesogen tributyltin (TBT), which activates the nuclear receptors peroxisome proliferator-activated receptor γ (PPARγ) and retinoid X receptor (RXR) to increase adiposity in mice exposed in utero. Mesenchymal stem cells (MSCs) from these mice are biased toward the adipose lineage at the expense of the osteoblast lineage, and MSCs exposed to TBT in vitro are shunted toward the adipose fate in a PPARγ-dependent fashion. To address where in the adipogenic cascade TBT acts, we developed an in vitro commitment assay that permitted us to distinguish early commitment to the adipose lineage from subsequent differentiation. TBT and RXR activators (rexinoids) had potent effects in committing MSCs to the adipose lineage, whereas the strong PPARγ activator rosiglitazone was inactive. We show that activation of RXR is sufficient for adipogenic commitment and that rexinoids act through RXR to alter the transcriptome in a manner favoring adipogenic commitment. RXR activation alters expression of enhancer of zeste homolog 2 (EZH2) and modifies genome-wide histone 3 lysine 27 trimethylation (H3K27me3) in promoting adipose commitment and programming subsequent differentiation. These data offer insights into the roles of RXR and EZH2 in MSC lineage specification and shed light on how endocrine-disrupting chemicals such as TBT can reprogram stem cell fate.
Undifferentiated mesenchymal stem cells are committed to the adipose lineage by activation of RXR but not PPARγ. This is mediated, in part, by a genome-wide reduction and redistribution of H3K27me3.
Recurrent selection methods have been successful in generating superior Paspalum notatum families through the accumulation of favorable alleles. However, the effectiveness of these methods in ...producing apomictic hybrids with superior agronomic traits has not been thoroughly evaluated. The aim of this study was to characterize the reproductive behavior of P. notatum progenies obtained through recurrent selection based on combining ability (RSCA) and recurrent phenotypic selection (RPS) and assess the performance of the apomictic hybrids concerning various agronomic traits. The reproductive mode of 144 RSCA and 144 RPS hybrids was determined using a molecular marker tightly linked to the apospory trait (BCU243‐377). The expressivity of apospory was estimated observing mature embryo sacs. The apomictic hybrids were then evaluated for six agronomic traits. A segregation ratio of 5:1 between sexual and apomictic hybrids was observed for the RSCA progeny, while 4.3:1 was registered for the RPS progeny. Although apospory expressivity was variable among hybrids, 75% and 86% of the RSCA and RPS hybrids, respectively, exhibited a high expression (>81%). Non‐significant differences between breeding methods in the number of apomictic hybrids and the level of apospory expressivity were observed. Variations for all agronomic traits were observed among apomictic hybrids within each breeding method. However, no differences between methods in the performance of the highly apomictic hybrids were observed. This demonstrates that the reproductive behavior of P. notatum is not affected by the recurrent selection method. Therefore, the RPS method would be the most suitable since it was equally effective than RSCA but it is cheaper, faster, and easier to apply.
Core Ideas
Highly apomictic hybrids with superior forage attributes were obtained by recurrent selection in Paspalum notatum.
The proportion of apomictic hybrids was not affected by the recurrent selection method.
Recurrent phenotypic selection would be the most suitable method for breeding Paspalum notatum.
Intracellular bacterial pathogens establish their replicative niches within membrane-encompassed compartments, called vacuoles. A subset of these bacteria uses a nanochannel called the type 4 ...secretion system (T4SS) to inject effector proteins that subvert the host cell machinery and drive the biogenesis of these compartments. These bacteria have also developed sophisticated ways of altering the innate immune sensing and response of their host cells, which allow them to cause long-lasting infections and chronic diseases. This review covers the mechanisms employed by intravacuolar pathogens to escape innate immune sensing and how Type 4-secreted bacterial effectors manipulate host cell mechanisms to allow the persistence of bacteria.
PDF
