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Background and objectivesExcessive adipose tissue macrophage accumulation in obesity has been implicated in mediating inflammatory responses that impair glucose homeostasis and promote insulin resistance. Colony-stimulating factor 1 (CSF1) controls macrophage differentiation, and here we sought to determine the effect of a CSF1 receptor inhibitor, PLX3397, on adipose tissue macrophage levels and understand the impact on glucose homeostasis in mice.MethodsA Ten-week-old mice were fed a chow or high-fat diet for 10 weeks and then treated with PLX3397 via oral gavage (50 mg/kg) every second day for 3 weeks, with subsequent monitoring of glucose tolerance, insulin sensitivity and assessment of adipose tissue immune cells.ResultsPLX3397 treatment substantially reduced macrophage numbers in adipose tissue of both chow and high-fat diet fed mice without affecting total myeloid cell levels. Despite this, PLX3397 did not greatly alter glucose homeostasis, did not affect high-fat diet-induced increases in visceral fat cytokine expression (Il-6 and Tnfa) and had limited effect on the phosphorylation of the stress kinases JNK and ERK and macrophage polarization.ConclusionsOur results indicate that macrophage infiltration of adipose tissue induced by a high-fat diet may not be the trigger for impairments in whole body glucose homeostasis, and that anti-CSF1 therapies are not likely to be useful as treatments for insulin resistance.

Single-cell technologies (RNA-sequencing, flow cytometry) are critical tools to reveal how cell heterogeneity impacts developmental pathways. The placenta is a fetal exchange organ, containing a heterogeneous mix of mesenchymal cells (fibroblasts, myofibroblasts, perivascular, and progenitor cells). Placental mesenchymal stromal cells (pMSC) are also routinely isolated, for therapeutic and research purposes. However, our understanding of the diverse phenotypes of placental mesenchymal lineages, and their relationships remain unclear. We designed a 23-colour flow cytometry panel to assess mesenchymal heterogeneity in first-trimester human placentae. Four distinct mesenchymal subsets were identified; CD73 + CD90 + mesenchymal cells, CD146 + CD271 + perivascular cells, podoplanin + CD36 + stromal cells, and CD26 + CD90 + myofibroblasts. CD73 + CD90 + and podoplanin + CD36+ cells expressed markers consistent with cultured pMSCs, and were explored further. Despite their distinct ex-vivo phenotype, in culture CD73 + CD90 + cells and podoplanin + CD36 + cells underwent phenotypic convergence, losing CD271 or CD36 expression respectively, and homogenously exhibiting a basic MSC phenotype (CD73 + CD90 + CD31 - CD144 - CD45 - ). However, some markers (CD26, CD146) were not impacted, or differentially impacted by culture in different populations. Comparisons of cultured phenotypes to pMSCs further suggested cultured pMSCs originate from podoplanin + CD36 + cells. This highlights the importance of detailed cell phenotyping to optimise therapeutic capacity, and ensure use of relevant cells in functional assays.

Abstract Background Most work testing links between emotional competencies and health has focused on self-reported and/or trait assessments. However, more objective assessments of skills and knowledge may also predict health relevant outcomes. Purpose The current study investigated whether performance-based tests of emotional knowledge and expressive skill predicted symptoms of depression and anxiety, self-reported physical symptoms, perceived health, and a range of immunoregulatory molecules. Methods Eighty females aged 18–35 completed self-report assessments before attending a testing session in which they provided blood samples and completed performance-based assessments of expressive skill and emotional knowledge. Results Greater expressive skill predicted better self-reported outcomes, but links to immunoregulatory molecules were mixed. Expressive skill for contempt and anger predicted higher, whereas skill for happiness predicted lower, concentrations of immunoregulatory molecules. Conclusions These data highlight the need to extend research beyond self-reported emotional competencies and suggest that performance-based skill and knowledge metrics may be associated with health relevant outcomes.

The pathogenesis of acute rheumatic fever (ARF) is poorly understood, limiting the development of immune-modulating therapies to treat disease and prevent progressive heart damage. Here, participants with definite ARF were compared to other severe acute paediatric conditions and matched healthy controls by profiling circulating immune molecules and cells to inform disease mechanisms and potential druggable pathways. ARF shared immunological similarities with other inflammatory conditions, including elevated serum IL-6 and an increased frequency of circulating CD4 + T cells. However, elevation of the chemokine CCL5 and immunoglobulin IgG3, along with reduced expression of the chemokine receptor CXCR3 in the T cell compartment distinguished ARF from all other groups. Immunofluorescence imaging of rheumatic valve tissue confirmed a role for CXCR3-mediated T cell tissue homing during inflammatory disease. Together with a reduced frequency of circulating regulatory T cells, these data underscore a perturbed T cell compartment and provide a rationale for exploring currently available immune-modulating therapies to treat ARF. Acute rheumatic fever (ARF) is a serious sequela of Strep A infection, for which a diagnostic biomarker is still lacking. Here, the authors demonstrate that CXCR3 directs T cells to heart valves in patients with ARF, linking inflammation to tissue damage.

Human adipose-derived mesenchymal stromal cells (ASC) are showing clinical promise for the treatment of a range of inflammatory and degenerative conditions. These lipoaspirate-derived cells are part of the abundant and accessible source of heterogeneous stromal vascular fraction (SVF). They are typically isolated and expanded from the SVF adherent cell culture for at least 2 weeks and as such represent a relatively undefined population of cells. We isolated ASC directly from lipoaspirate using a cocktail of antibodies combined with immunomagnetic bead sorting. This method allowed for the rapid enrichment of a defined and untouched ASC population (referred to as MACS-derived ASC) that were then compared to culture-derived ASC. This comparison found that MACS-derived ASC contain a greater proportion of cells with activity in differentiation assays. There were also significant differences in the secretion levels of some key paracrine molecules. Moreover, when the MACS-derived ASC were subjected to adherent tissue culture, rapid changes in gene expression were observed. This indicates that culturing cells may alter the clinical utility of these cells. Although MACS-derived ASC are more defined compared to culture-derived ASC, further investigations using a comprehensive multicolor flow cytometry panel revealed that this cell population is more heterogeneous than previously appreciated. Additional studies are therefore required to more precisely delineate phenotypically distinct ASC subsets with the most therapeutic potential. This research highlights the disparity between MACS-derived and culture-derived ASC and the need for further characterization.

Macrophages play essential roles in maintaining tissue homeostasis and immune defence. However, their extensive infiltration into tumours has been linked to adverse outcomes in multiple human cancers. Within the tumour microenvironment (TME), tumour-associated macrophages (TAMs) promote tumour growth and metastasis, making them prime targets for cancer immunotherapy. Recent single-cell analysis suggest that proliferating TAMs accumulate in human cancers, yet their origins and differentiation pathways remain uncertain. Here, we show that a subpopulation of CD163+ TAMs proliferates in situ within the TME of melanoma, lung cancer, and breast cancer. Consistent with their potential role in suppressing anti-tumour activities of T cells, CD163+ TAMs express a range of potent immunosuppressive molecules, including PD-L1, PD-L2, IL-10, and TGF-β. Other phenotypic markers strongly suggested that these cells originate from CD14+ CCR2+ monocytes, a cell population believed to have minimal capacity for proliferation. However, we demonstrate in vitro that certain myelopoietic cytokines commonly available within the TME induce robust proliferation of human monocytes, especially the combination of interleukin 3 (IL-3) and Macrophage Colony-Stimulating Factor 1 (M-CSF). Monocytic cells cultured with these cytokines efficiently modulate T cell proliferation, and their molecular phenotype recapitulates that of CD163+ TAMs. IL-3-driven proliferation of monocytic cells can be completely blocked by IL-4, associated with the induction of CDKN1A, alongside the upregulation of transcription factors linked to dendritic cell function, such as BATF3 and IRF4. Taken together, our work suggests several novel therapeutic routes to reducing immunosuppressive TAMs in human tumours, from blocking chemokine-mediated recruitment of monocytes to blocking their proliferation.

Background. The profile of cellular immunological responses of children across the spectrum of COVID-19, ranging from acute SARS-CoV-2 infection to full recovery or Long COVID, has not yet been fully investigated. Methods. We examined and compared cytokines in sera and cell subsets in peripheral blood mononuclear cells (B and regulatory T lymphocytes) collected from four distinct groups of children, distributed as follows: younger than 18 years of age with either acute SARS-CoV-2 infection (n = 49); fully recovered from COVID-19 (n = 32); with persistent symptoms (Long COVID, n = 51); and healthy controls (n = 9). Results. In the later stages after SARS-CoV-2 infection, the cohorts of children, both with recovered and persistent symptoms, showed skewed T and B subsets, with remarkable differences when compared with children at the onset of the infection and with controls. The frequencies of IgD+CD27− naïve B cells, IgD+IgM+ and CD27−IgM+CD38dim B cells were higher in children with recent infection than in those with an older history of disease (p < 0.0001 for all); similarly, the total and natural Tregs compartments were more represented in children at onset when compared with Long COVID (p < 0.0001 and p = 0.0005, respectively). Despite the heterogeneity, partially due to age, sex and infection incidence, the susceptibility of certain children to develop persistent symptoms after infection appeared to be associated with the imbalance of the adaptive immune response. Following up and comparing recovered versus Long COVID patients, we analyzed the role of circulating naïve and switched B and regulatory T lymphocytes in counteracting the evolution of the symptomatology emerged, finding an interesting correlation between the amount and ability to reconstitute the natural Tregs component with the persistence of symptoms (linear regression, p = 0.0026). Conclusions. In this study, we suggest that children affected by Long COVID may have a compromised ability to switch from the innate to the adaptive immune response, as supported by our data showing a contraction of naïve and switched B cell compartment and an unstable balance of regulatory T lymphocytes occurring in these children. However, further prospective immunological studies are needed to better clarify which factors (epigenetic, diet, environment, etc.) are involved in the impairment of the immunological mechanisms in the Long COVID patients.

Purpose Common Variable Immunodeficiency Disorder (CVID) is a complex disorder that predisposes patients to recurrent and severe infections. The C104R mutation in the transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) is the most frequent mutation identified in patients with CVID. We carried out a detailed immunological and molecular study in a family with a C104R mutation. Methods We have undertaken segregation analysis of a kindred with C104R mutations of the TACI gene. Detailed immunological and molecular investigations were carried out for this kindred and the clinical phenotype was compared to the genotype. Results Segregation analysis of our kindred showed that inheriting single or double copy of the C104R mutation does not consign an individual to CVID. All heterozygotes in the family were phenotypically different, ranging from asymptomatic to ill-health. A family member with a wild type TACI variant had CVID-related phenotype including IgA deficiency and type 1 diabetes. Interestingly, a family member with the homozygous C104R/C104R variant did not meet the criteria for CVID because he had excellent, albeit unsustained, vaccine responses to T cell dependent and T cell independent vaccine antigens despite profound hypogammaglobulinemia. Conclusion The C104R mutation does not correlate with the clinical phenotypes in this family.

Background Trichomonas vaginalis , the causative agent of a prevalent urogenital infection in humans, is an evolutionarily divergent protozoan. Protein-coding genes in T. vaginalis are largely controlled by two core promoter elements, producing mRNAs with short 5′ UTRs. The specific mechanisms adopted by T. vaginalis to fine-tune the translation efficiency (TE) of mRNAs remain largely unknown. Results Using both computational and experimental approaches, this study investigated two key factors influencing TE in T. vaginalis : codon usage and mRNA secondary structure. Statistical dependence between TE and codon adaptation index (CAI) highlighted the impact of codon usage on mRNA translation in T. vaginalis . A genome-wide interrogation revealed that low structural complexity at the 5′ end of mRNA followed closely by a highly structured downstream region correlates with TE variation in this organism. To validate these findings, a synthetic library of 15 synonymous iLOV genes was created, representing five mRNA folding profiles and three codon usage profiles. Fluorescence signals produced by the expression of these synonymous iLOV genes in T. vaginalis were consistent with and validated our in silico predictions. Conclusions This study demonstrates the role of codon usage bias and mRNA secondary structure in TE of T. vaginalis mRNAs, contributing to a better understanding of the factors that influence, and possibly regulate, gene expression in this human pathogen.