CXCR3 chemokine receptor contributes to specific CD8+ T cell activation by pDC during infection with intracellular pathogens

Immune cell profiles associated with human exposure to perfluorinated compounds (PFAS) suggest changes in natural killer, T helper, and T cytotoxic cell subpopulations

Per- and polyfluoroalkyl substances (PFAS) constitutes a group of highly persistent man-made substances. Recent evidence indicates that PFAS negatively impact the immune system. However, it remains unclear how different PFAS are associated with alterations in circulating leukocyte subpopulations. More detailed knowledge of such potential associations can provide better understanding into mechanisms of PFAS immunotoxicity in humans. In this exploratory study, associations of serum levels of common PFAS (perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS)) and immune cell profiles of peripheral blood mononuclear cells, both with and without immunostimulation, were investigated. High-dimensional single cell analysis by mass cytometry was done on blood leukocytes from fifty participants in the Norwegian human biomonitoring EuroMix study. Different PFAS were associated with changes in various subpopulations of natural killer (NK), T helper (Th), and cytotoxic T (Tc) cells. Broadly, PFAS concentrations were related to increased frequencies of NK cells and activated subpopulations of NK cells. Additionally, increased levels of activated T helper memory cell subpopulations point to Th2/Th17 and Treg-like skewed profiles. Finally, PFAS concentrations were associated with decreased frequencies of T cytotoxic cell subpopulations with CXCR3+ effector memory (EM) phenotypes. Several of these observations point to biologically plausible mechanisms that may contribute to explaining the epidemiological reports of immunosuppression by PFAS. Our results suggest that PFAS exposures even at relatively low levels are associated with changes in immune cell subpopulations, a finding which should be explored more thoroughly in a larger cohort. Additionally, causal relationships should be confirmed in experimental studies. Overall, this study demonstrates the strength of profiling by mass cytometry in revealing detailed changes in immune cells at a single cell level.

Vagus nerve modulates acute-on-chronic liver failure progression via CXCL9

BACKGROUND

Hepatic inflammatory cell accumulation and the subsequent systematic inflammation drive acute-on-chronic liver failure (ACLF) development. Previous studies showed that the vagus nerve exerts anti-inflammatory activity in many inflammatory diseases. Here, we aimed to identify the key molecule mediating the inflammatory process in ACLF and reveal the neuroimmune communication arising from the vagus nerve and immunological disorders of ACLF.

METHODS

Proteomic analysis was performed and validated in ACLF model mice or patients, and intervention animal experiments were conducted using neutralizing antibodies. PNU-282987 (acetylcholine receptor agonist) and vagotomy were applied for perturbing vagus nerve activity. Single-cell RNA sequencing (scRNA-seq), flow cytometry, immunohistochemical and immunofluorescence staining, and CRISPR/Cas9 technology were used for in vivo or in vitro mechanistic studies.

RESULTS

The unbiased proteomics identified C-X-C motif chemokine ligand 9 (CXCL9) as the greatest differential protein in the livers of mice with ACLF and its relation to the systematic inflammation and mortality were confirmed in patients with ACLF. Interventions on CXCL9 and its receptor C-X-C chemokine receptor 3 (CXCR3) improved liver injury and decreased mortality of ACLF mice, which were related to the suppressing of hepatic immune cells' accumulation and activation. Vagus nerve stimulation attenuated while vagotomy aggravated the expression of CXCL9 and the severity of ACLF. Blocking CXCL9 and CXCR3 ameliorated liver inflammation and increased ACLF-associated mortality in ACLF mice with vagotomy. scRNA-seq revealed that hepatic macrophages served as the major source of CXCL9 in ACLF and were validated by immunofluorescence staining and flow cytometry analysis. Notably, the expression of CXCL9 in macrophages was modulated by vagus nerve-mediated cholinergic signaling.

CONCLUSIONS

Our novel findings highlighted that the neuroimmune communication of the vagus nerve-macrophage-CXCL9 axis contributed to ACLF development. These results provided evidence for neuromodulation as a promising approach for preventing and treating ACLF.

Integrated transcriptomic analysis reveals immune signatures distinguishing persistent versus resolving outcomes in MRSA bacteremia

Introduction

Staphylococcus aureus bacteremia (SAB) is a life-threatening infection particularly involving methicillin-resistant S. aureus (MRSA). In contrast to resolving MRSA bacteremia (RB), persistent MRSA bacteremia (PB) blood cultures remain positive despite appropriate antibiotic treatment. Host immune responses distinguishing PB vs. RB outcomes are poorly understood. Here, integrated transcriptomic, IL-10 cytokine levels, and genomic analyses sought to identify signatures differentiating PB vs. RB outcomes.

Methods

Whole-blood transcriptomes of propensity-matched PB (n=28) versus RB (n=30) patients treated with vancomycin were compared in one independent training patient cohort. Gene expression (GE) modules were analyzed and prioritized relative to host IL-10 cytokine levels and DNA methyltransferase-3A (DNMT3A) genotype.

Results

Differential expression of T and B lymphocyte gene expression early in MRSA bacteremia discriminated RB from PB outcomes. Significant increases in effector T and B cell signaling pathways correlated with RB, lower IL-10 cytokine levels and DNMT3A heterozygous A/C genotype. Importantly, a second PB and RB patient cohort analyzed in a masked manner demonstrated high predictive accuracy of differential signatures.

Discussion

Collectively, the present findings indicate that human PB involves dysregulated immunity characterized by impaired T and B cell responses associated with excessive IL-10 expression in context of the DNMT3A A/A genotype. These findings reveal distinct immunologic programs in PB vs. RB outcomes, enable future studies to define mechanisms by which host and/or pathogen drive differential signatures and may accelerate prediction of PB outcomes. Such prognostic assessment of host risk could significantly enhance early anti-infective interventions to avert PB and improve patient outcomes.

Lombana C, Beiting D, Novais F, P. Carvalho L, M. Carvalho E, Scott P. CCR5 promotes the migration of pathological CD8+ T cells to the leishmanial lesions

Cytolytic CD8+ T cells mediate immunopathology in cutaneous leishmaniasis without controlling parasites. Here, we identify factors involved in CD8+ T cell migration to the lesion that could be targeted to ameliorate disease severity. CCR5 was the most highly expressed chemokine receptor in patient lesions, and the high expression of CCL3 and CCL4, CCR5 ligands, was associated with delayed healing of lesions. To test the requirement for CCR5, Leishmania-infected Rag1-/- mice were reconstituted with CCR5-/- CD8+ T cells. We found that these mice developed smaller lesions accompanied by a reduction in CD8+ T cell numbers compared to controls. We confirmed these findings by showing that the inhibition of CCR5 with maraviroc, a selective inhibitor of CCR5, reduced lesion development without affecting the parasite burden. Together, these results reveal that CD8+ T cells migrate to leishmanial lesions in a CCR5-dependent manner and that blocking CCR5 prevents CD8+ T cell-mediated pathology.

Therapeutic utility of human umbilical cord-derived mesenchymal stem cells-based approaches in pulmonary diseases: Recent advancements and prospects

Pulmonary diseases across all ages threaten millions of people and have emerged as one of the major public health issues worldwide. For diverse disease conditions, the currently available approaches are focused on alleviating clinical symptoms and delaying disease progression but have not shown significant therapeutic effects in patients with lung diseases. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) isolated from the human UC have the capacity for self-renewal and multilineage differentiation. Moreover, in recent years, these cells have been demonstrated to have unique advantages in the treatment of lung diseases. We searched the Public Clinical Trial Database and found 55 clinical trials involving UC-MSC therapy for pulmonary diseases, including coronavirus disease 2019, acute respiratory distress syndrome, bronchopulmonary dysplasia, chronic obstructive pulmonary disease, and pulmonary fibrosis. In this review, we summarize the characteristics of these registered clinical trials and relevant published results and explore in depth the challenges and opportunitiesfaced in clinical application. Moreover, the underlying molecular mechanisms involved in UC-MSC-based therapy for pulmonary diseases are also analyzed in depth. In brief, this comprehensive review and detailed analysis of these clinical trials can be expected to provide a scientific reference for future large-scale clinical application.

CCR5 promotes the migration of CD8+ T cells to the leishmanial lesions

Cytolytic CD8+ T cells mediate immunopathology in cutaneous leishmaniasis without controlling parasites. Here, we identify factors involved in CD8+ T cell migration to the lesion that could be targeted to ameliorate disease severity. CCR5 was the most highly expressed chemokine receptor in patient lesions, and the high expression of CCL3 and CCL4, CCR5 ligands, was associated with delayed healing of lesions. To test the requirement for CCR5, Leishmania-infected Rag1-/- mice were reconstituted with CCR5-/- CD8+ T cells. We found that these mice developed smaller lesions accompanied by a reduction in CD8+ T cell numbers compared to controls. We confirmed these findings by showing that the inhibition of CCR5 with maraviroc, a selective inhibitor of CCR5, reduced lesion development without affecting the parasite burden. Together, these results reveal that CD8+ T cells migrate to leishmanial lesions in a CCR5-dependent manner and that blocking CCR5 prevents CD8+ T cell-mediated pathology.

Lung adenocarcinoma manifesting as subsolid nodule potentially represents tumour in the equilibrium phase of immunoediting

Lung adenocarcinomas manifesting as subsolid nodules (SSN-LUADs) possess distinct dormant behaviour. This study was designed to compare the immune landscapes of normal lungs (nLungs), SSN-LUADs and LUADs manifesting as solid nodules (SN-LUADs) so as to better understand the status of anti-tumour immunity in SSN-LUADs. Mass cytometry by time-of-flight analysis was performed on 299, 570 single cells from nLung, SSN-LUAD and SN-LUAD tissues. The immune cells were identified by phenotype, and the percentages of different immune cell subclusters were compared between SSN-LUADs, SN-LUADs and nLungs. Elevated percentage of CD8⁺ T cells were identified in SSN-LUADs compared with in nLungs and SN-LUADs. Elevated CD56^bright NK cells and decreased CD56^dim NK cells were identified in both SSN-LUADs and SN-LUADs compared with in nLungs. The immune landscape of SSN-LUAD fits the theory of equilibrium phase of immunoediting, thus functional adaptive anti-tumour immunity but impaired innate anti-tumour immunity potentially contributes to the maintaining of its dormant behaviour.

Common trajectories of highly effective CD19-specific CAR T cells identified by endogenous T cell receptor lineages

Current chimeric antigen receptor-modified (CAR) T cell products are evaluated in bulk, without assessing functional heterogeneity. We therefore generated a comprehensive single-cell gene expression and T cell receptor (TCR) sequencing dataset using pre- and post-infusion CD19-CAR T cells from blood and bone marrow samples of pediatric patients with B cell acute lymphoblastic leukemia (B-ALL). We identified cytotoxic post-infusion cells with identical TCRs to a subset of pre-infusion CAR T cells. These effector precursor cells exhibited a unique transcriptional profile compared to other pre-infusion cells, corresponding to an unexpected surface phenotype (TIGIT+, CD62Llo, CD27-). Upon stimulation, these cells showed functional superiority and decreased expression of the exhaustion-associated transcription factor, TOX. Collectively, these results demonstrate diverse effector potentials within pre-infusion CAR T cell products, which can be exploited for therapeutic applications. Furthermore, we provide an integrative experimental and analytical framework for elucidating the mechanisms underlying effector development in CAR T cell products.

Transcriptomic Analysis of the Effects of Chemokine Receptor CXCR3 Deficiency on Immune Responses in the Mouse Brain during Toxoplasma gondii Infection

The obligate intracellular parasite Toxoplasma gondii infects warm-blooded animals, including humans. We previously revealed through a whole-brain transcriptome analysis that infection with T. gondii in mice causes immune response-associated genes to be upregulated, for instance, chemokines and chemokine receptors such as CXC chemokine receptor 3 (CXCR3) and its ligand CXC chemokine ligand 10 (CXCL10). Here, we describe the effect of CXCR3 on responses against T. gondii infection in the mouse brain. In vivo assays using CXCR3-deficient mice showed that the absence of CXCR3 delayed the normal recovery of body weight and increased the brain parasite burden, suggesting that CXCR3 plays a role in the control of pathology in the brain, the site where chronic infection occurs. Therefore, to further analyze the function of CXCR3 in the brain, we profiled the gene expression patterns of primary astrocytes and microglia by RNA sequencing and subsequent analyses. CXCR3 deficiency impaired the normal upregulation of immune-related genes during T. gondii infection, in astrocytes and microglia alike. Collectively, our results suggest that the immune-related genes upregulated by CXCR3 perform a particular role in controlling pathology when the host is chronically infected with T. gondii in the brain.

Umbilical cord mesenchymal stromal cells as critical COVID-19 adjuvant therapy: A randomized controlled trial

One of the main causes of acute respiratory distress syndrome in coronavirus disease 2019 (COVID-19) is cytokine storm, although the exact cause is still unknown. Umbilical cord mesenchymal stromal cells (UC-MSCs) influence proinflammatory T-helper 2 (Th₂ ) cells to shift to an anti-inflammatory agent. To investigate efficacy of UC-MSC administration as adjuvant therapy in critically ill patients with COVID-19, we conducted a double-blind, multicentered, randomized controlled trial at four COVID-19 referral hospitals in Jakarta, Indonesia. This study included 40 randomly allocated critically ill patients with COVID-19; 20 patients received an intravenous infusion of 1 × 10⁶ /kg body weight UC-MSCs in 100 ml saline (0.9%) solution (SS) and 20 patients received 100 ml 0.9% SS as the control group. All patients received standard therapy. The primary outcome was measured by survival rate and/or length of ventilator usage. The secondary outcome was measured by clinical and laboratory improvement, with serious adverse events. Our study showed the survival rate in the UC-MSCs group was 2.5 times higher than that in the control group (P = .047), which is 10 patients and 4 patients in the UC-MSCs and control groups, respectively. In patients with comorbidities, UC-MSC administration increased the survival rate by 4.5 times compared with controls. The length of stay in the intensive care unit and ventilator usage were not statistically significant, and no adverse events were reported. The application of infusion UC-MSCs significantly decreased interleukin 6 in the recovered patients (P = .023). Therefore, application of intravenous UC-MSCs as adjuvant treatment for critically ill patients with COVID-19 increases the survival rate by modulating the immune system toward an anti-inflammatory state.

Human CD8 T-stem cell memory subsets phenotypic and functional characterization are defined by expression of CD122 or CXCR3

Long-lived T-memory stem cells (T_SCM ) are key to both naturally occurring and vaccine-conferred protection against infection. These cells are characterized by the CD45RA⁺ CCR7⁺ CD95⁺ phenotype. Significant heterogeneity within the T_SCM population is recognized, but distinguishing surface markers and functional characterization of potential subsets are lacking. Human CD8 T_SCM subsets were identified in healthy subjects who had been previously exposed to CMV or Influenza (Flu) virus in flow cytometry by expression of CD122 or CXCR3, and then characterized in proliferation, multipotency, self-renewal, and intracellular cytokine production (TNF-α, IL-2, IFN-γ), together with transcriptomic profiles. The T_SCM CD122^hi -expressing subset (versus CD122^lo ) demonstrated greater proliferation, greater multipotency, and enhanced polyfunctionality with higher frequencies of triple positive (TNF-α, IL-2, IFN-γ) cytokine-producing cells upon exposure to recall antigen. The T_SCM CXCR3^lo subpopulation also had increased proliferation and polyfunctional cytokine production. Transcriptomic analysis further showed that the T_SCM CD122^hi population had increased expression of activation and homing molecules, such as Ccr6, Cxcr6, Il12rb, and Il18rap, and downregulated cell proliferation inhibitors, S100A8 and S100A9. These data reveal that the T_SCM CD122^hi phenotype is associated with increased proliferation, enhanced multipotency and polyfunctionality with an activated memory-cell like transcriptional profile, and hence, may be favored for induction by immunization and for adoptive immunotherapy.