iPS-cell-derived microglia promote brain organoid maturation via cholesterol transfer

Microglia are specialized brain-resident macrophages that arise from primitive macrophages colonizing the embryonic brain1. Microglia contribute to multiple aspects of brain development, but their precise roles in the early human brain remain poorly understood owing to limited access to relevant tissues2-6. The generation of brain organoids from human induced pluripotent stem cells recapitulates some key features of human embryonic brain development7-10. However, current approaches do not incorporate microglia or address their role in organoid maturation11-21. Here we generated microglia-sufficient brain organoids by coculturing brain organoids with primitive-like macrophages generated from the same human induced pluripotent stem cells (iMac)22. In organoid cocultures, iMac differentiated into cells with microglia-like phenotypes and functions (iMicro) and modulated neuronal progenitor cell (NPC) differentiation, limiting NPC proliferation and promoting axonogenesis. Mechanistically, iMicro contained high levels of PLIN2+ lipid droplets that exported cholesterol and its esters, which were taken up by NPCs in the organoids. We also detected PLIN2+ lipid droplet-loaded microglia in mouse and human embryonic brains. Overall, our approach substantially advances current human brain organoid approaches by incorporating microglial cells, as illustrated by the discovery of a key pathway of lipid-mediated crosstalk between microglia and NPCs that leads to improved neurogenesis.

Mitochondrial Dysfunction in CD4+ T Effector Memory RA+ Cells

Human ageing is accompanied by poor responses to infection and decreased vaccine efficacy. While the causes of this can be attributed to defects in the immune system that increase with age, it is unknown whether mitochondrial dysfunction may also contribute to these phenomena. This study aims to assess mitochondrial dysfunction in CD4+ terminal effector memory T cells re-expressing CD45RA (TEMRA) cells and other CD4+ memory T cell subtypes, which are increased in number in the elderly population, with respect to how their metabolic responses to stimulation are altered compared to CD4+ naïve T cells. In this study, we show that CD4+ TEMRA cells exhibit altered mitochondrial dynamics compared to CD4+ naïve cells and CD4+ central and effector memory cells, with a 25% reduction in OPA1 expression. CD4+ TEMRA and memory cells show increased upregulation of Glucose transporter 1 following stimulation and higher levels of mitochondrial mass compared to CD4+ naïve T cells. Additionally, TEMRA cells exhibit a decrease in mitochondrial membrane potential compared to other CD4+ memory cell subsets by up to 50%. By comparing young to aged individuals, more significant mitochondria mass and lower membrane potential were observed in CD4+ TEMRA of young individuals. In conclusion, we suggest that CD4+ TEMRA cells may be impaired with respect to their metabolic response to stimulation, possibly contributing to impaired responses to infection and vaccination.

A subset of Kupffer cells regulates metabolism through the expression of CD36

Tissue macrophages are immune cells whose phenotypes and functions are dictated by origin and niches. However, tissues are complex environments, and macrophage heterogeneity within the same organ has been overlooked so far. Here, we used high-dimensional approaches to characterize macrophage populations in the murine liver. We identified two distinct populations among embryonically derived Kupffer cells (KCs) sharing a core signature while differentially expressing numerous genes and proteins: a major CD206^loESAM^- population (KC1) and a minor CD206^hiESAM⁺ population (KC2). KC2 expressed genes involved in metabolic processes, including fatty acid metabolism both in steady-state and in diet-induced obesity and hepatic steatosis. Functional characterization by depletion of KC2 or targeted silencing of the fatty acid transporter Cd36 highlighted a crucial contribution of KC2 in the liver oxidative stress associated with obesity. In summary, our study reveals that KCs are more heterogeneous than anticipated, notably describing a subpopulation wired with metabolic functions.

The socio-economic impact of multidrug-resistant nosocomial infections: a qualitative study

The burden of healthcare-associated infections (HCAIs) has traditionally been measured using clinical and economic outcomes. We conducted semi-structured interviews with 18 patients or their caregivers affected by HCAI caused by multidrug-resistant organisms to better understand the human impact of HCAI. Most patients had misconceptions about HCAI and antimicrobial resistance, leading to strong negative feelings towards HCAIs despite positive views of their healthcare providers. Communication issues across power imbalances need to be addressed to help deal with trauma of HCAIs. A holistic approach to HCAIs incorporating patient perspectives will likely help guide policymakers developing solutions to improve patient outcomes.

Induced-Pluripotent-Stem-Cell-Derived Primitive Macrophages Provide a Platform for Modeling Tissue-Resident Macrophage Differentiation and Function

Tissue macrophages arise during embryogenesis from yolk-sac (YS) progenitors that give rise to primitive YS macrophages. Until recently, it has been impossible to isolate or derive sufficient numbers of YS-derived macrophages for further study, but data now suggest that induced pluripotent stem cells (iPSCs) can be driven to undergo a process reminiscent of YS-hematopoiesis in vitro. We asked whether iPSC-derived primitive macrophages (iMacs) can terminally differentiate into specialized macrophages with the help of growth factors and organ-specific cues. Co-culturing human or murine iMacs with iPSC-derived neurons promoted differentiation into microglia-like cells in vitro. Furthermore, murine iMacs differentiated in vivo into microglia after injection into the brain and into functional alveolar macrophages after engraftment in the lung. Finally, iPSCs from a patient with familial Mediterranean fever differentiated into iMacs with pro-inflammatory characteristics, mimicking the disease phenotype. Altogether, iMacs constitute a source of tissue-resident macrophage precursors that can be used for biological, pathophysiological, and therapeutic studies.

Mapping the human DC lineage through the integration of high-dimensional techniques

Dendritic cells (DC) are professional antigen-presenting cells that orchestrate immune responses. The human DC population comprises two main functionally specialized lineages, whose origins and differentiation pathways remain incompletely defined. Here, we combine two high-dimensional technologies-single-cell messenger RNA sequencing (scmRNAseq) and cytometry by time-of-flight (CyTOF)-to identify human blood CD123⁺CD33⁺CD45RA⁺ DC precursors (pre-DC). Pre-DC share surface markers with plasmacytoid DC (pDC) but have distinct functional properties that were previously attributed to pDC. Tracing the differentiation of DC from the bone marrow to the peripheral blood revealed that the pre-DC compartment contains distinct lineage-committed subpopulations, including one early uncommitted CD123^high pre-DC subset and two CD45RA⁺CD123^low lineage-committed subsets exhibiting functional differences. The discovery of multiple committed pre-DC populations opens promising new avenues for the therapeutic exploitation of DC subset-specific targeting.

C-Myb(+) erythro-myeloid progenitor-derived fetal monocytes give rise to adult tissue-resident macrophages

Although classified as hematopoietic cells, tissue-resident macrophages (MFs) arise from embryonic precursors that seed the tissues prior to birth to generate a self-renewing population, which is maintained independently of adult hematopoiesis. Here we reveal the identity of these embryonic precursors using an in utero MF-depletion strategy and fate-mapping of yolk sac (YS) and fetal liver (FL) hematopoiesis. We show that YS MFs are the main precursors of microglia, while most other MFs derive from fetal monocytes (MOs). Both YS MFs and fetal MOs arise from erythro-myeloid progenitors (EMPs) generated in the YS. In the YS, EMPs gave rise to MFs without monocytic intermediates, while EMP seeding the FL upon the establishment of blood circulation acquired c-Myb expression and gave rise to fetal MOs that then seeded embryonic tissues and differentiated into MFs. Thus, adult tissue-resident MFs established from hematopoietic stem cell-independent embryonic precursors arise from two distinct developmental programs.

γ/δ T cell subsets in human aging using the classical α/β T cell model

Aging is associated with an increased susceptibility to infections and diseases. It has also been associated with reduced functionality and altered distribution of immune cells, especially T cells. Whereas classical α/β T cells, especially CD8(+) T cells, were shown to be highly susceptible to aging, the effects of viral persistent stimulations on the fate of γ/δ T cells are much less documented. Healthy, elderly individuals of Chinese ethnical background were recruited under the aegis of SLAS-II. In this observational study, γ/δ T cell populations were characterized by flow cytometry and compared with the α/β CD4(+) and CD8(+) T cells in elderly and young controls. In our study, we identified a reduced frequency of γ/δ T cells but not α/β T cells with aging. The classical markers of α/β T cell aging, including CD28, CD27, and CD57, did not prove significant for γ/δ T cells. The extreme range of expression of these markers in γ/δ T cells was responsible for the lack of relationship between γ/δ T cell subsets, CD4/CD8 ratio, and anti-CMV titers that was significant for α/β T cells and, especially, CD8(+) T cells. Although markers of aging for γ/δ T cells are not clearly identified, our data collectively suggest that the presence of CD27 γ/δ T cells is associated with markers of α/β T cell aging.

The immune system in the elderly: a fair fight against diseases?

The immune system is a very dynamic network, consisting of various innate and adaptive cells acting via direct cell–cell contact, as well as indirect messaging mediated by soluble factors. Changes in the number or quality of receptors involved in these events alter the capacity of the immune system to respond properly. There is an increasing awareness that many chronic infections and diseases, such as cytomegalovirus, impact on the immune system. Concurrently, there are changes in immune profiles of healthy, as well as ill, elderly individuals. All these changes translate into obvious signs of immunological aging that are more profound in diseases. This review will discuss the manifestation of different diseases in the elderly and how the immune system behaves in such situations.

Multi-parametric phospho-flow cytometry: a crucial tool for T lymphocyte signaling studies

Tools such as protein immunoblotting have proven benefits for investigating T lymphocyte signaling but have several drawbacks such as the number of cells required and the difficulty of distinguishing subset-specific differences without expensive and invasive cell sorting. Recent advances in immunology and the identification of T lymphocyte sub-populations making up only a very small fraction of the total population highlight the importance of studying signaling in those small subsets in a feasible, cost-effective, high-throughput manner. To this end, we have developed a simplified protocol to study both intracellular phosphorylation patterns of important signal transduction molecules concomitantly with T cell surface marker expression. A multi-parametric analysis may allow the quantification of the phosphorylation of up to five signaling molecules in CD4 and CD8 T lymphocytes and their naïve, central memory, effector memory, and TEMRA subsets. This enables precise identification of subset-specific signaling and alterations of signaling pathways in physiological and pathological situations. The importance of such detailed analysis is discussed.

Retrospective review of prognostic factors, including 1p19q deletion, in low-grade oligodendrogliomas and a review of recent published works

The purpose of the present study was to investigate potential prognostic factors in low-grade oligodendrogliomas (LGOs), particularly 1p19q deletion, due to its proven prognostic significance in anaplastic oligodendrogliomas. We carried out a retrospective review of patients with a histological diagnosis of LGO between 1990 and 2000 in Auckland and Wellington, New Zealand. All cases underwent central histopathological review and FISH testing for 1p19q status. Univariate analysis of potential prognostic factors including 1p19q status, age, tumour size, tumour crossing midline, tumour enhancement, extent of surgery and seizures at diagnosis was carried out. Thirty-one patients were eligible and FISH testing was successful in 28 specimens (90%). Twenty-three specimens (82%) had 1p19q deletion; four (14%) had no 1p19q deletion; and one (4%) had 1p deletion alone. At a median follow-up of 87 months (0-147 months), median survival had not been reached and no significant difference in overall survival (OS) based on 1p19q status was detected (1p19q deletion OS 56%; 1p19q intact OS 0%; 1p deletion alone 100% (P = 0.38)). None of the other prognostic factors investigated reached statistical significance. We confirmed the high incidence (82%) of combined 1p19q deletion in LGOs and the feasibility of successful FISH testing in paraffin embedded specimens up to 10-years-old. Analysis of potential prognostic factors was limited by the lack of events during the follow-up period.

Epithelioid trophoblastic tumor: a case report

Epithelioid trophoblastic tumor is a rare and distinctive pathologic entity within the complex family of gestational trophoblastic disease. We describe a case of epithelioid trophoblastic tumor occurring in a 34-year-old woman, who presented with a large uterine tumor 3 years following an uncomplicated pregnancy. The clinicopathologic findings in this case are typical of this unusual entity and consistent with current literature, with the exception of negative beta-human chorionic gonadotrophin levels. The distinguishing features from other intermediate trophoblastic tumors and tumor-like lesions are discussed.

Epithelioid trophoblastic tumor: a case report

Epithelioid trophoblastic tumor is a rare and distinctive pathologic entity within the complex family of gestational trophoblastic disease. We describe a case of epithelioid trophoblastic tumor occurring in a 34-year-old woman, who presented with a large uterine tumor 3 years following an uncomplicated pregnancy. The clinicopathologic findings in this case are typical of this unusual entity and consistent with current literature, with the exception of negative beta-human chorionic gonadotrophin levels. The distinguishing features from other intermediate trophoblastic tumors and tumor-like lesions are discussed.

Approach to risk reduction in manufacturing firms in Australia

A survey of the 100 largest manufacturing firms in Australia has revealed that there is a lack of emphasis on controlling the incidence of high severity injuries and diseases. In a considerable number of organizations, there appears to be a reliance on the attitude of employees and safety training to control risk. There seems to be a lack of knowledge among the respondents of information sources which can be used to assess both risk and proposed control measures. The results suggest that Robens type legislation may be of limited utility in controlling risk in the workplace and a more definitive approach to identifying hazards and instituting appropriate control measures should be provided to organizations.

Absence and labour turnover in a foundry attributable to respiratory disease

A survey of foundry workers was undertaken to assess the effect of respiratory disease on both absence in the year prior to the survey and labour turnover since a cross-sectional study of respiratory morbidity five years previously. The presence of a wheeze, but not an objective disturbance of airway function, was predictive of absence. Those with respiratory illness, detected in the survey five years previously, were no more likely to have left the foundry than those without such illness. Limited job opportunities may discourage moulders with respiratory disease from leaving the foundry. Absence was not related to cigarette smoking, the presence of bronchial hyperreactivity, or a positive skin test to common allergens. In view of the small number of subjects in this study, studies of larger work populations should be undertaken to further assess the effect of subjective and objective indices of respiratory morbidity on absence and labour turnover.

Respiratory disease in foundry workers

A survey was carried out in a steel foundry in Brisbane to evaluate the nature and frequency of respiratory symptoms and to assess ventilatory function. The foundry used many moulding processes including the Furane, Isocure, Shell, carbon dioxide, and oil sand systems. Nasal symptoms and wheeze were often reported, particularly by workers in the general foundry and core shop, and on a semiautomated line. By contrast, workers in the aftercast section not exposed to fumes or vapours from the various moulding processes reported these symptoms less often. Of 46 workers exposed to moulding fumes and vapours, 11 had developed a wheeze while working at the foundry. Wheeze and other respiratory tract symptoms were often attributed by the workers to exposure to substances at work, particularly from the Shell process which uses phenol formaldehyde resin and hexamethylenetetramine. Symptoms were reported also, but less often, on exposure to materials used in the Furane process (urea formaldehyde and furfuryl alcohol) and the Isocure process (methylene diphenyl diisocyanate, phenol formaldehyde, and dimethylethylamine). Ventilatory function studied over Monday and Friday showed a small and inconsistent changes. The six subjects working on the semiautomated line showed a small decrease in FEV1 (+/- SEM) (208 +/- 70 ml) only on Monday; this differed significantly from that in 17 aftercast workers (9 +/- 50 ml, p less than 0.05). Ventilatory function recorded before work on Monday morning showed no evidence of chronic airway obstruction in any group. Most environmental measurements were below the threshold limit values (TLV) except in the general foundry, where furfuryl alcohol was detected at concentrations of up to 50 ppm and formaldehyde at 4 ppm. The onset of symptoms in relation to exposure to various fumes and vapours suggests that both irritant and hypersensitivity mechanisms are present. As environmental modifications had occurred recently the apparent hypersensitivity may relate to past exposure levels above the TLV.