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 CD206loESAM- population (KC1) and a minor CD206hiESAM+ 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.

Combinatorial Single-Cell Analyses of Granulocyte-Monocyte Progenitor Heterogeneity Reveals an Early Uni-potent Neutrophil Progenitor.

Granulocyte-monocyte progenitors (GMPs) have been previously defined for their potential to generate various myeloid progenies such as neutrophils and monocytes. Although studies have proposed lineage heterogeneity within GMPs, it is unclear if committed progenitors already exist among these progenitors and how they may behave differently during inflammation. By combining single-cell transcriptomic and proteomic analyses, we identified the early committed progenitor within the GMPs responsible for the strict production of neutrophils, which we designate as proNeu1. Our dissection of the GMP hierarchy led us to further identify a previously unknown intermediate proNeu2 population. Similar populations could be detected in human samples. proNeu1s, but not proNeu2s, selectively expanded during the early phase of sepsis at the expense of monocytes. Collectively, our findings help shape the neutrophil maturation trajectory roadmap and challenge the current definition of GMPs.

Bystander CD8+ T cells are abundant and phenotypically distinct in human tumour infiltrates.

Various forms of immunotherapy, such as checkpoint blockade immunotherapy, are proving to be effective at restoring T cell-mediated immune responses that can lead to marked and sustained clinical responses, but only in some patients and cancer types1-4. Patients and tumours may respond unpredictably to immunotherapy partly owing to heterogeneity of the immune composition and phenotypic profiles of tumour-infiltrating lymphocytes (TILs) within individual tumours and between patients5,6. Although there is evidence that tumour-mutation-derived neoantigen-specific T cells play a role in tumour control2,4,7-10, in most cases the antigen specificities of phenotypically diverse tumour-infiltrating T cells are largely unknown. Here we show that human lung and colorectal cancer CD8+ TILs can not only be specific for tumour antigens (for example, neoantigens), but also recognize a wide range of epitopes unrelated to cancer (such as those from Epstein-Barr virus, human cytomegalovirus or influenza virus). We found that these bystander CD8+ TILs have diverse phenotypes that overlap with tumour-specific cells, but lack CD39 expression. In colorectal and lung tumours, the absence of CD39 in CD8+ TILs defines populations that lack hallmarks of chronic antigen stimulation at the tumour site, supporting their classification as bystanders. Expression of CD39 varied markedly between patients, with some patients having predominantly CD39- CD8+ TILs. Furthermore, frequencies of CD39 expression among CD8+ TILs correlated with several important clinical parameters, such as the mutation status of lung tumour epidermal growth factor receptors. Our results demonstrate that not all tumour-infiltrating T cells are specific for tumour antigens, and suggest that measuring CD39 expression could be a straightforward way to quantify or isolate bystander T cells.

Robust Virus-Specific Adaptive Immunity in COVID-19 Patients with SARS-CoV-2 Δ382 Variant Infection.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) that have become dominant as the pandemic progresses bear the ORF8 mutation together with multiple spike mutations. A 382-nucleotide deletion (Δ382) in the ORF7b and ORF8 regions has been associated with milder disease phenotype and less systemic inflammation in COVID-19 patients. However, its impact on host immunity against SARS-CoV-2 remains undefined. Here, RNA-sequencing was performed to elucidate whole blood transcriptomic profiles and identify contrasting immune signatures between patients infected with either wildtype or Δ382 SARS-CoV-2 variant. Interestingly, the immune landscape of Δ382 SARS-CoV-2 infected patients featured an increased adaptive immune response, evidenced by enrichment of genes related to T cell functionality, a more robust SARS-CoV-2-specific T cell immunity, as well as a more rapid antibody response. At the molecular level, eukaryotic initiation factor 2 signaling was found to be upregulated in patients bearing Δ382, and its associated genes were correlated with systemic levels of T cell-associated and pro-inflammatory cytokines. This study provides more in-depth insight into the host-pathogen interactions of ORF8 with great promise as a therapeutic target to combat SARS-CoV-2 infection.

Crosstalk between CD64+MHCII+ macrophages and CD4+ T cells drives joint pathology during chikungunya.

Communications between immune cells are essential to ensure appropriate coordination of their activities. Here, we observed the infiltration of activated macrophages into the joint-footpads of chikungunya virus (CHIKV)-infected animals. Large numbers of CD64+MHCII+ and CD64+MHCII- macrophages were present in the joint-footpad, preceded by the recruitment of their CD11b+Ly6C+ inflammatory monocyte precursors. Recruitment and differentiation of these myeloid subsets were dependent on CD4+ T cells and GM-CSF. Transcriptomic and gene ontology analyses of CD64+MHCII+ and CD64+MHCII- macrophages revealed 89 differentially expressed genes, including genes involved in T cell proliferation and differentiation pathways. Depletion of phagocytes, including CD64+MHCII+ macrophages, from CHIKV-infected mice reduced disease pathology, demonstrating that these cells play a pro-inflammatory role in CHIKV infection. Together, these results highlight the synergistic dynamics of immune cell crosstalk in driving CHIKV immunopathogenesis. This study provides new insights in the disease mechanism and offers opportunities for development of novel anti-CHIKV therapeutics.

Palliative Sedation Therapy Practice Comparison - A Survey of Pediatric Palliative Care and Pain Management Specialists.

Context: Palliative sedation therapy (PST) can relieve suffering at end-of-life (EOL) in children with intolerable and refractory symptoms. However, updated and consistent guidance on PST practices are imperative. Objectives: We investigate current variations in clinical practice and PST implementation among pediatric palliative care (PPC) and pain management (PM) specialists. Methods: We distributed an IRB-exempt electronic anonymous survey via email through the Society of Pediatric Pain Medicine, and the American Academy of Hospice and Palliative Medicine. Survey responses were collated and descriptively reported. Results: Of 83 survey responses, the majority (75%) represented large academic children's hospitals. The distribution between PPC and pediatric pain management specialists' responses was 60% and 40%, respectively. Most respondents reported having designated pain management and/or palliative care teams (70% and 90%, respectively). Approximately half (48%) reported following an institutional PST protocol, most not requiring formal ethics consult (69%). Only 54% of respondents noted that the Do Not Resuscitate (DNR) order was required prior to PST initiation. PST was primarily utilized for children with oncologic diagnoses (76%). The primary and secondary medications of choice for PST implementation were reported to be opioids (39%) and benzodiazepines (36%) by pain management specialists, and benzodiazepines (52%) and barbiturates (28%) by palliative care specialists. Conclusions: Our study highlights the variability in the practice and implementation of PST. Further educational efforts are key for establishing PST practices and efficient protocol development.

The promise and challenge of spatial omics in dissecting tumour microenvironment and the role of AI.

Growing evidence supports the critical role of tumour microenvironment (TME) in tumour progression, metastases, and treatment response. However, the in-situ interplay among various TME components, particularly between immune and tumour cells, are largely unknown, hindering our understanding of how tumour progresses and responds to treatment. While mainstream single-cell omics techniques allow deep, single-cell phenotyping, they lack crucial spatial information for in-situ cell-cell interaction analysis. On the other hand, tissue-based approaches such as hematoxylin and eosin and chromogenic immunohistochemistry staining can preserve the spatial information of TME components but are limited by their low-content staining. High-content spatial profiling technologies, termed spatial omics, have greatly advanced in the past decades to overcome these limitations. These technologies continue to emerge to include more molecular features (RNAs and/or proteins) and to enhance spatial resolution, opening new opportunities for discovering novel biological knowledge, biomarkers, and therapeutic targets. These advancements also spur the need for novel computational methods to mine useful TME insights from the increasing data complexity confounded by high molecular features and spatial resolution. In this review, we present state-of-the-art spatial omics technologies, their applications, major strengths, and limitations as well as the role of artificial intelligence (AI) in TME studies.

Acute changes in handgrip strength, lung function and health-related quality of life following cardiac surgery.

BACKGROUND: Handgrip strength (HGS), lung function and health-related quality of life (HRQoL) are relevant indicators of future cardiovascular risk and mortality. The impact of cardiac surgery on these predictive variables has been under-explored. The aim of this study was to determine the acute (within hospital) changes in HGS, lung function and HRQoL, and their relationships, in adults undergoing elective cardiac surgery. Further, the study examined the relationship between these variables and the predictors for lung function and HRQoL in these patients. METHODS: The study was a prospective cohort study that involved 101 patients who completed pre-operative (1-2 days before surgery) and physiotherapy discharge (5-7 days after surgery) assessments. Handgrip strength, lung function and HRQoL were assessed using JAMAR dynamometers, Vitalograph-Alpha or EasyOne spirometer, and Short-Form 36 questionnaire, respectively. Changes in these variables and their relationships were analysed using paired t-test and Pearson correlation coefficients, respectively. Prediction of lung function and HRQoL using HGS and other co-variates was conducted using regression analysis. RESULTS: At the time of physiotherapy discharge, lung function, HGS and the physical component of HRQoL were significantly (<0.001) reduced compared to their pre-operative values. Significant (<0.001) and moderate correlations were identified between HGS and lung function at pre-operation and physiotherapy discharge. Handgrip strength was a significant predictor of lung function pre-operatively but not at physiotherapy discharge. Pre-operative lung function and HRQoL, as well as other variables, were significant predictors of lung function and HRQoL during physiotherapy discharge. CONCLUSIONS: Undergoing cardiac surgery acutely and significantly reduced lung function, HGS and physical component of HRQoL in adults with cardiac disease. Assessment of HGS at physiotherapy discharge may be a poor indicator of operative changes in lung function and HRQoL. Clinicians may consider HGS as an inadequate tool in predicting lung function and HRQoL following cardiac surgery.

Prevalence of traumatic brain injury among the guests at a low-barrier homeless shelter.

OBJECTIVE: This study aimed at determining the prevalence of traumatic brain injuries (TBI) among guests staying at a low-barrier homeless shelter who represent an especially vulnerable subset of individuals experiencing homelessness. RESULTS: A total of 21 out of 35 shelter guests participated in the survey. We found that 17 (81.0%) had experienced at least one traumatic brain injury in their lifetime and 15 (71.3%) had TBI associated with loss of consciousness. In addition, 7 (33.3%) of the participants had experienced TBIs rated as moderate to severe. Of the participants with head trauma history, 16 (94.1%) experienced their injury before their first onset of homelessness. Compared to both the general population and the broader population of individuals experiencing homelessness, those in this sample were significantly more likely to experience TBI (95% CI 0.0000:0.2857; p < 0.001 and 95% CI 0.3333:0.7619; p < 0.015, respectively) and significantly more likely to experience severe TBI (95% CI 0.0000:0.09524; p < 0.001).

Midkine-a functions as a universal regulator of proliferation during epimorphic regeneration in adult zebrafish.

Zebrafish have the ability to regenerate damaged cells and tissues by activating quiescent stem and progenitor cells or reprogramming differentiated cells into regeneration-competent precursors. Proliferation among the cells that will functionally restore injured tissues is a fundamental biological process underlying regeneration. Midkine-a is a cytokine growth factor, whose expression is strongly induced by injury in a variety of tissues across a range of vertebrate classes. Using a zebrafish Midkine-a loss of function mutant, we evaluated regeneration of caudal fin, extraocular muscle and retinal neurons to investigate the function of Midkine-a during epimorphic regeneration. In wildtype zebrafish, injury among these tissues induces robust proliferation and rapid regeneration. In Midkine-a mutants, the initial proliferation in each of these tissues is significantly diminished or absent. Regeneration of the caudal fin and extraocular muscle is delayed; regeneration of the retina is nearly completely absent. These data demonstrate that Midkine-a is universally required in the signaling pathways that convert tissue injury into the initial burst of cell proliferation. Further, these data highlight differences in the molecular mechanisms that regulate epimorphic regeneration in zebrafish.