CD44 regulates survival and memory development in Th1 cells

A review of CD4+ T cell differentiation and diversity in dogs

CD4+ T cells are an integral component of the adaptive immune response, carrying out many functions to combat a diverse range of pathogenic challenges. These cells exhibit remarkable plasticity, differentiating into specialized subsets such as T helper type 1 (TH1), TH2, TH9, TH17, TH22, regulatory T cells (Tregs), and follicular T helper (TFH) cells. Each subset is capable of addressing a distinct immunological need ranging from pathogen eradication to regulation of immune homeostasis. As the immune response subsides, CD4+ T cells rest down into long-lived memory phenotypes-including central memory (TCM), effector memory (TEM), resident memory (TRM), and terminally differentiated effector memory cells (TEMRA) that are localized to facilitate a swift and potent response upon antigen re-encounter. This capacity for long-term immunological memory and rapid reactivation upon secondary exposure highlights the role CD4+ T cells play in sustaining both adaptive defense mechanisms and maintenance. Decades of mouse, human, and to a lesser extent, pig T cell research has provided the framework for understanding the role of CD4+ T cells in immune responses, but these model systems do not always mimic each other. Although our understanding of pig immunology is not as extensive as mouse or human research, we have gained valuable insight by studying this model. More akin to pigs, our understanding of CD4+ T cells in dogs is much less complete. This disparity exists in part because canine immunologists depend on paradigms from mouse and human studies to characterize CD4+ T cells in dogs, with a fraction of available lineage-defining antibody markers. Despite this, every major CD4+ T cell subset has been described to some extent in dogs. These subsets have been studied in various contexts, including in vitro stimulation, homeostatic conditions, and across a range of disease states. Canine CD4+ T cells have been categorized according to lineage-defining characteristics, trafficking patterns, and what cytokines they produce upon stimulation. This review addresses our current understanding of canine CD4+ T cells from a comparative perspective by highlighting both the similarities and differences from mouse, human, and pig CD4+ T cell biology. We also discuss knowledge gaps in our current understanding of CD4+ T cells in dogs that could provide direction for future studies in the field.

Immunization of turkeys with Clostridium septicum alpha toxin-based recombinant subunit proteins can confer protection against experimental Clostridial dermatitis

Clostridial dermatitis (CD), caused by Clostridium septicum, is an emerging disease of increasing economic importance in turkeys. Currently, there are no effective vaccines for CD control. Here, two non-toxic domains of C. septicum alpha toxin, namely ntATX-D1 and ntATX-D2, were identified, cloned, and expressed in Escherichia coli as recombinant subunit proteins to investigate their use as potential vaccine candidates. Experimental groups consisted of a Negative control (NCx) that did not receive C. septicum challenge, while the adjuvant-only Positive control (PCx), ntATX-D1 immunization (D1) and ntATX-D2 immunization (D2) groups received C. septicum challenge. Turkeys were immunized subcutaneously with 100 μg of protein at 7, 8 and 9 weeks of age along with an oil-in-water nano-emulsion adjuvant, followed by C. septicum challenge at 11 weeks of age. Results showed that while 46.2% of birds in the PCx group died post-challenge, the rate of mortality in D1- or D2-immunization groups was 13.3%. The gross and histopathological lesions in the skin, muscle and spleen showed that the disease severity was highest in PCx group, while the D2-immunized birds had significantly lower lesion scores when compared to PCx. Gene expression analysis revealed that PCx birds had significantly higher expression of pro-inflammatory cytokine genes in the skin, muscle and spleen than the NCx group, while the D2 group had significantly lower expression of these genes compared to PCx. Peripheral blood cellular analysis showed increased frequencies of activated CD4+ and/or CD8+ cells in the D1 and D2-immunized groups. Additionally, the immunized turkeys developed antigen-specific serum IgY antibodies. Collectively, these findings indicate that ntATX proteins, specifically the ntATX-D2 can be a promising vaccine candidate for protecting turkeys against CD and that the protection mechanisms may include downregulation of C. septicum-induced inflammation and increased CD4+ and CD8+ cellular activation.

Evaluation of Adjuvant Effect of Cytosine-Guanosine-Oligodeoxynucleotide in Meat-Type Chickens Coadministered In Ovo with Herpesvirus of Turkey Vaccine

Herpesvirus of turkey (HVT) increases activation of T cells in 1-day-old chickens when administered in ovo. This study evaluated whether adding cytosine-guanosine oligodeoxynucleotides (CpG ODNs) to the HVT vaccine could enhance the adjuvant effect of HVT. We used a CpG ODN dose of 10 μg per egg. The experimental groups were (1) diluent-only control (sham), (2) HVT, (3) HVT+CpG ODN, (4) HVT+non-CpG ODN, (5) CpG ODN, and (6) non-CpG ODN control. Cellular response evaluation included measuring the frequencies of macrophages (KUL01+MHC-II+), gamma delta T cells (γδTCR+MHC-II+), CD4+, and CD8+ T cell subsets, including double-positive (DP) cells. In addition, CD4+ and CD8+ T cell activation was evaluated by measuring the cellular expression of major histocompatibility complex class II (MHC-II), CD44 or CD28 costimulatory molecules. An adjuvant effect was considered when HVT+CpG ODN, but not HVT+non CpG ODN, or CpG ODN, or non-CpG ODN, induced significantly increased effects on any of the immune parameters examined when compared with HVT. The findings showed that (1) HVT vaccination induced significantly higher frequencies of γδ+MHC-II+ and CD4+CD28+ T cells when compared with sham chickens. Frequencies of DP and CD4+CD28+ T cells in HVT-administered birds were significantly higher than those observed in the non-CpG ODN group. (2) Groups receiving HVT+CpG ODN or CpG ODN alone were found to have significantly increased frequencies of activated CD4+ and CD8+ T cells, when compared with HVT. Our results show that CpG ODN administration in ovo with or without HVT significantly increased frequencies of activated CD4+ and CD8+ T cells.

Immunobiology of cancer stem cells and their immunoevasion mechanisms

Cancer stem cells (CSCs) defined as a small fraction of cells within malignancies have been isolated from tumors with different histological origins with stem related characteristics such as self-replicating potential, tumorigenesis, and therapy resistance. The dynamic communication between CSCs and tumor microenvironment particularly immune cells orchestrates their fate and plasticity as well as the patient outcome. According to recent evidence, it has been reported that they harness different immunological pathways to escape immunosurveillance and express aberrantly immunomodulatory agents or decreased levels of factors forming antigen presenting machinery (APM), subsequently followed by impaired antigen presentation and suppressed immune detection. As effective therapies are expected to be able to eradicate CSCs, mechanistic understanding of such interactions can provide insights into causes of therapy failure particularly in immunotherapy. Also, it can contribute to enhance the practical interventions against CSCs and their immunomodulatory features resulting in CSCs eradication and improving patient clinical outcome. The aim of this review is to explain the present knowledge regarding the immunobiology of CSCs and the immunoevasion mechanisms they use.

In Ovo Vaccination with Recombinant Herpes Virus of the Turkey-Laryngotracheitis Vaccine Adjuvanted with CpG-Oligonucleotide Provides Protection against a Viral Challenge in Broiler Chickens

Infectious laryngotracheitis (ILT) is an economically important disease in chickens. We previously showed that an in ovo adjuvantation of recombinant herpesvirus of the turkey-Laryngotracheitis (rHVT-LT) vaccine with CpG-oligonucleotides (ODN) can boost vaccine-induced responses in one-day-old broiler chickens. Here, we evaluated the protective efficacy of in ovo administered rHVT-LT + CpG-ODN vaccination against a wild-type ILT virus (ILTV) challenge at 28 days of age and assessed splenic immune gene expression as well as cellular responses. A chicken-embryo-origin (CEO)-ILT vaccine administered in water at 14 days of age was also used as a comparative control for the protection assessment. The results showed that the rHVT-LT + CpG-ODN or the CEO vaccinations provided significant protection against the ILTV challenge and that the level of protection induced by both the vaccines was statistically similar. The protected birds had a significantly upregulated expression of interferon (IFN)γ or interleukin (IL)-12 cytokine genes. Furthermore, the chickens vaccinated with the rHVT-LT + CpG-ODN or CEO vaccine had a significantly higher frequency of γδ T cells and activated CD4+ or CD8+ T cells, compared to the unvaccinated-ILTV challenge control. Collectively, our findings suggest that CpG-ODN can be used as an effective adjuvant for rHVT-LT in ovo vaccination to induce protective immunity against ILT in broiler chickens.

Overexpressed CD44 is associated with B-cell activation via the HA-CD44-AIM2 pathway in lupus B cells

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by aberrant development of B cells and excess production of autoantibodies. Our team previously reported that absent in melanoma 2 (AIM2) regulates B-cell differentiation via the Bcl-6-Blimp-1 axis. Notably, in keyhole limpet hemocyanin (KLH)-immunized CD19creAim2f/f mice, the frequency of CD19+CD44+ B cells was decreased, accompanied by a weakened KLH response, indicating that AIM2 deficiency suppressed the antigen-induced B-cell immune response by downregulating the expression of CD44. CD44, a surface marker of T-cell activation and memory, was overexpressed in T cells of SLE patients, but its roles and mechanism in B cells have not been elucidated. In the current work, we revealed that CD44 expression was upregulated in the B cells of SLE patients and MRL/lpr mice, accompanied by elevated AIM2 expression in CD19+CD44+ B-cell subsets, and that its ligand hyaluronan (HA) was also abnormally increased in the serum of SLE patients. Notably, the extrafollicular (EF) region serves as an important site of B-cell activation and differentiation separate from the germinal center, while CD44 expression is concentrated in EF B cells. In addition, in vitro experiments demonstrated that the HA-CD44 interaction stimulated B-cell activation and upregulated the expression of AIM2 and the transcription factor STAT3. Either blocking CD44, knocking down AIM2 expression or suppressing the activity of STAT3 in B cells suppressed B-cell activation and proliferation. Moreover, blocking CD44 downregulated the expression of STAT3 and AIM2, while suppressing the activity of STAT3 decreased the expression of CD44 and AIM2. In summary, overexpressed CD44 in B cells might participate in B-cell activation and proliferation in the EF region via the HA-CD44-AIM2 pathway, providing potential targets for SLE therapy.

Autistic spectrum disorder (ASD) - Gene, molecular and pathway signatures linking systemic inflammation, mitochondrial dysfunction, transsynaptic signalling, and neurodevelopment

Background

Despite advances in autism spectrum disorder (ASD) research and the vast genomic, transcriptomic, and proteomic data available, there are still controversies regarding the pathways and molecular signatures underlying the neurodevelopmental disorders leading to ASD.

Purpose

To delineate these underpinning signatures, we examined the two largest gene expression meta-analysis datasets obtained from the brain and peripheral blood mononuclear cells (PBMCs) of 1355 ASD patients and 1110 controls.

Methods

We performed network, enrichment, and annotation analyses using the differentially expressed genes, transcripts, and proteins identified in ASD patients.

Results

Transcription factor network analyses in up- and down-regulated genes in brain tissue and PBMCs in ASD showed eight main transcription factors, namely: BCL3, CEBPB, IRF1, IRF8, KAT2A, NELFE, RELA, and TRIM28. The upregulated gene networks in PBMCs of ASD patients are strongly associated with activated immune-inflammatory pathways, including interferon-α signaling, and cellular responses to DNA repair. Enrichment analyses of the upregulated CNS gene networks indicate involvement of immune-inflammatory pathways, cytokine production, Toll-Like Receptor signalling, with a major involvement of the PI3K-Akt pathway. Analyses of the downregulated CNS genes suggest electron transport chain dysfunctions at multiple levels. Network topological analyses revealed that the consequent aberrations in axonogenesis, neurogenesis, synaptic transmission, and regulation of transsynaptic signalling affect neurodevelopment with subsequent impairments in social behaviours and neurocognition. The results suggest a defense response against viral infection.

Conclusions

Peripheral activation of immune-inflammatory pathways, most likely induced by viral infections, may result in CNS neuroinflammation and mitochondrial dysfunction, leading to abnormalities in transsynaptic transmission, and brain neurodevelopment.

Cellular Immune Responses in Lymphoid Tissues of Broiler Chickens Experimentally Infected with Necrotic Enteritis-Producing Clostridium perfringens Strains

Host cellular responses against Clostridium perfringens (CP), the causative agent of necrotic enteritis (NE) in chickens, are poorly understood. In the present study, we first tested the NE-producing ability of seven netB+ CP strains (CP5, CP18, CP26, CP64, CP67, CP68, and NCNE-1), using an experimental infection model of broiler chickens. Evaluation of intestinal gross lesions showed that all the strains, except CP5, were able to produce NE, while CP26 and CP64 strains produced relatively more severe lesions when compared with other groups. Next, cellular responses in the cecal tonsil (CT), bursa of Fabricius, and spleen were evaluated in chickens infected with strains representing variation in the level of virulence, namely, avirulent CP5, virulent CP18, and a relatively more virulent CP26 strain. Immunophenotyping analysis showed that CT or splenic macrophage frequencies were significantly higher in CP18- and CP26-infected chickens compared with uninfected controls, while the frequencies of γδ T-cells and B-cells in the CT of CP26-infected chickens were significantly higher than those in the uninfected, CP5- or CP18-infected groups. The T-cell analysis showed that chickens infected with CP18 and CP26 had a significantly higher number of splenic CD4+ and CD8+ T-cells expressing CD44 and CD28 activation molecules, while CP26-infected chickens also had significantly increased CT frequency of these activated CD4+ and CD8+ T-cells when compared with uninfected or CP5-infected groups. Collectively, our findings suggested that cellular responses, including activation of T-cells, are selectively induced against virulent CP strains and that the NE-producing characteristics of this pathogen may influence the outcome of immunity to NE.

In Situ Vaccination Following Intratumoral Injection of IL2 and Poly-l-lysine/Iron Oxide/CpG Nanoparticles to a Radiated Tumor Site

The in situ vaccine effect of radiation therapy (RT) has been shown to be limited in both preclinical and clinical settings, possibly due to the inadequacy of RT alone to stimulate in situ vaccination in immunologically "cold" tumor microenvironments (TMEs) and the mixed effects of RT in promoting tumor infiltration of both effector and suppressor immune cells. To address these limitations, we combined intratumoral injection of the radiated site with IL2 and a multifunctional nanoparticle (PIC). The local injection of these agents produced a cooperative effect that favorably immunomodulated the irradiated TME, enhancing the activation of tumor-infiltrating T cells and improving systemic anti-tumor T cell immunity. In syngeneic murine tumor models, the PIC+IL2+RT combination significantly improved the tumor response, surpassing the single or dual combinations of these treatments. Furthermore, this treatment led to the activation of tumor-specific immune memory and improved abscopal effects. Our findings suggest that this strategy can be used to augment the in situ vaccine effect of RT in clinical settings.

The potential crosstalk between tumor and plasma cells and its association with clinical outcome and immunotherapy response in bladder cancer

BACKGROUND

Although immunotherapy is effective in improving the clinical outcomes of patients with bladder cancer (BC), it is only effective in a small percentage of patients. Intercellular crosstalk in the tumor microenvironment strongly influences patient response to immunotherapy, while the crosstalk patterns of plasma cells (PCs) as endogenous antibody-producing cells remain unknown. Here, we aimed to explore the heterogeneity of PCs and their potential crosstalk patterns with BC tumor cells.

METHODS

Crosstalk patterns between PCs and tumor cells were revealed by performing integrated bulk and single-cell RNA sequencing (RNA-seq) and spatial transcriptome data analysis. A risk model was constructed based on ligand/receptor to quantify crosstalk patterns by stepwise regression Cox analysis.

RESULTS

Based on cell infiltration scores inferred from bulk RNA-seq data (n = 728), we found that high infiltration of PCs was associated with better overall survival (OS) and response to immunotherapy in BC. Further single-cell transcriptome analysis (n = 8; 41,894 filtered cells) identified two dominant types of PCs, IgG1 and IgA1 PCs. Signal transduction from tumor cells of specific states (stress-like and hypoxia-like tumor cells) to PCs, for example, via the LAMB3/CD44 and ANGPTL4/SDC1 ligand/receptor pairs, was validated by spatial transcriptome analysis and associated with poorer OS as well as nonresponse to immunotherapy. More importantly, a ligand/receptor pair-based risk model was constructed and showed excellent performance in predicting patient survival and immunotherapy response.

CONCLUSIONS

PCs are an important component of the tumor microenvironment, and their crosstalk with tumor cells influences clinical outcomes and response to immunotherapies in BC patients.

Biomaterial-based platforms for modulating immune components against cancer and cancer stem cells

Immunotherapy involves the therapeutic alteration of the patient's immune system to identify, target, and eliminate cancer cells. Dendritic cells, macrophages, myeloid-derived suppressor cells, and regulatory T cells make up the tumor microenvironment. In cancer, these immune components (in association with some non-immune cell populations like cancer-associated fibroblasts) are directly altered at a cellular level. By dominating immune cells with molecular cross-talk, cancer cells can proliferate unchecked. Current clinical immunotherapy strategies are limited to conventional adoptive cell therapy or immune checkpoint blockade. Targeting and modulating key immune components presents an effective opportunity. Immunostimulatory drugs are a research hotspot, but their poor pharmacokinetics, low tumor accumulation, and non-specific systemic toxicity limit their use. This review describes the cutting-edge research undertaken in the field of nanotechnology and material science to develop biomaterials-based platforms as effective immunotherapeutics. Various biomaterial types (polymer-based, lipid-based, carbon-based, cell-derived, etc.) and functionalization methodologies for modulating tumor-associated immune/non-immune cells are explored. Additionally, emphasis has been laid on discussing how these platforms can be used against cancer stem cells, a fundamental contributor to chemoresistance, tumor relapse/metastasis, and failure of immunotherapy. Overall, this comprehensive review strives to provide up-to-date information to an audience working at the juncture of biomaterials and cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Cancer immunotherapy possesses incredible potential and has successfully transitioned into a clinically lucrative alternative to conventional anti-cancer therapies. With new immunotherapeutics getting rapid clinical approval, fundamental problems associated with the dynamic nature of the immune system (like limited clinical response rates and autoimmunity-related adverse effects) have remained unanswered. In this context, treatment approaches that focus on modulating the compromised immune components within the tumor microenvironment have garnered significant attention amongst the scientific community. This review aims to provide a critical discussion on how various biomaterials (polymer-based, lipid-based, carbon-based, cell-derived, etc.) can be employed along with immunostimulatory agents to design innovative platforms for selective immunotherapy directed against cancer and cancer stem cells.

In ovo HVT vaccination enhances cellular responses at hatch and addition of poly I:C offers minimal adjuvant effects

In ovo vaccination with herpesvirus of turkey (HVT) hastens immunocompetence in chickens and the recommended dose (RD) of 6080 plaque-forming-units (PFU) offers the most optimal effects. In previous studies conducted in egg-type chickens, in ovo vaccination with HVT enhanced lymphoproliferation, wing-web thickness with phytohemagglutinin-L (PHA-L), and increased spleen and lung interferon-gamma(IFN-γ) andToll-like receptor 3 (TLR3) transcripts. Here, we evaluated the cellular mechanisms by which HVT-RD can hasten immunocompetence in one-day-old meat-type chickens, and also determined if HVT adjuvantation with a TLR3 agonist, polyinosinic-polycytidylic acid (poly(I:C)), could enhance vaccine-induced responses and provide dose-sparing effects. Compared to sham-inoculated chickens, HVT-RD significantly increased transcription of splenic TLR3 and IFN γ receptor 2 (R2), and lung IFN γ R2, while the splenic IL-13 transcription was found decreased. Additionally, these birds showed increased wing-web thickness following PHA-L inoculation. The thickness was due to an innate inflammatory cell population, CD3⁺ T cells, and edema. In another experiment, HVT-1/2 (3040 PFU) supplemented with 50 μg poly(I:C) [HVT-1/2 + poly(I:C)] was administered in ovo and immune responses were compared with those produced by HVT-RD, HVT-1/2, 50 μg poly(I:C), and sham-inoculated. Immunophenotyping of splenocytes showed HVT-RD induced a significantly higher frequency of CD4⁺, CD4⁺MHC-II⁺, CD8⁺CD44⁺, and CD4⁺CD28⁺ T cells compared to sham-inoculated chickens, and CD8⁺MHC-II⁺, CD4⁺CD8⁺, CD4⁺CD8⁺CD28⁺, and CD4⁺CD8⁺CD44⁺ T cells compared to all groups. Treatment groups, except HVT-1/2 + poly(I:C), had significantly higher frequencies of γδ T cells and all groups induced significantly higher frequencies of activated monocytes/macrophages, compared to sham-inoculated chickens. Poly(I:C)-induced dose-sparing effect was only observed in the frequency of activated monocytes/macrophages. No differences in the humoral responses were observed. Collectively, HVT-RD downregulated IL-13 transcripts (Th2 immune response) and had strong immunopotentiation effects on innate immune responses and the activation of T cells. However addition of poly(I:C) offered a minimal adjuvant/dose-sparing effect.

Phenotypic signatures of immune selection in HIV-1 reservoir cells

Human immunodeficiency virus 1 (HIV-1) reservoir cells persist lifelong despite antiretroviral treatment1,2 but may be vulnerable to host immune responses that could be exploited in strategies to cure HIV-1. Here we used a single-cell, next-generation sequencing approach for the direct ex vivo phenotypic profiling of individual HIV-1-infected memory CD4+ T cells from peripheral blood and lymph nodes of people living with HIV-1 and receiving antiretroviral treatment for approximately 10 years. We demonstrate that in peripheral blood, cells harbouring genome-intact proviruses and large clones of virally infected cells frequently express ensemble signatures of surface markers conferring increased resistance to immune-mediated killing by cytotoxic T and natural killer cells, paired with elevated levels of expression of immune checkpoint markers likely to limit proviral gene transcription; this phenotypic profile might reduce HIV-1 reservoir cell exposure to and killing by cellular host immune responses. Viral reservoir cells harbouring intact HIV-1 from lymph nodes exhibited a phenotypic signature primarily characterized by upregulation of surface markers promoting cell survival, including CD44, CD28, CD127 and the IL-21 receptor. Together, these results suggest compartmentalized phenotypic signatures of immune selection in HIV-1 reservoir cells, implying that only small subsets of infected cells with optimal adaptation to their anatomical immune microenvironment are able to survive during long-term antiretroviral treatment. The identification of phenotypic markers distinguishing viral reservoir cells may inform future approaches for strategies to cure and eradicate HIV-1.

Effect of CpG-Oligonucleotide in Enhancing Recombinant Herpes Virus of Turkey-Laryngotracheitis Vaccine-Induced Immune Responses in One-Day-Old Broiler Chickens

Infectious laryngotracheitis (ILT) is an economically important disease of chickens. While the recombinant vaccines can reduce clinical disease severity, the associated drawbacks are poor immunogenicity and delayed onset of immunity. Here, we used CpG-oligonucleotides (ODN) as an in ovo adjuvant in boosting recombinant herpesvirus of turkey-laryngotracheitis (rHVT-LT) vaccine-induced responses in one-day-old broiler chickens. Two CpG-ODN doses (5 and 10 μg/egg) with no adverse effect on the vaccine-virus replication or chick hatchability were selected for immune-response evaluation. Results showed that while CpG-ODN adjuvantation induced an increased transcription of splenic IFNγ and IL-1β, and lung IFNγ genes, the IL-1β gene expression in the lung was significantly downregulated compared to the control. Additionally, the transcription of toll-like receptor (TLR)21 in the spleen and lung and inducible nitric oxide synthase (iNOS) in the spleen of all vaccinated groups was significantly reduced. Furthermore, splenic cellular immunophenotyping showed that the CpG-ODN-10μg adjuvanted vaccination induced a significantly higher number of macrophages, TCRγδ+, and CD4+ T cells as well as a higher frequency of activated T cells (CD4+CD44+) when compared to the control. Collectively, the findings suggested that CpG-ODN can boost rHVT-LT-induced immune responses in day-old chicks, which may help in anti-ILT defense during their later stages of life.

Low-density lipoprotein balances T cell metabolism and enhances response to anti-PD-1 blockade in a HCT116 spheroid model

Introduction

The discovery of immune checkpoints and the development of their specific inhibitors was acclaimed as a major breakthrough in cancer therapy. However, only a limited patient cohort shows sufficient response to therapy. Hence, there is a need for identifying new checkpoints and predictive biomarkers with the objective of overcoming immune escape and resistance to treatment. Having been associated with both, treatment response and failure, LDL seems to be a double-edged sword in anti-PD1 immunotherapy. Being embedded into complex metabolic conditions, the impact of LDL on distinct immune cells has not been sufficiently addressed. Revealing the effects of LDL on T cell performance in tumor immunity may enable individual treatment adjustments in order to enhance the response to routinely administered immunotherapies in different patient populations. The object of this work was to investigate the effect of LDL on T cell activation and tumor immunity in-vitro.

Methods

Experiments were performed with different LDL dosages (LDL^low = 50 μg/ml and LDL^high = 200 μg/ml) referring to medium control. T cell phenotype, cytokines and metabolism were analyzed. The functional relevance of our findings was studied in a HCT116 spheroid model in the context of anti-PD-1 blockade.

Results

The key points of our findings showed that LDL^high skewed the CD4⁺ T cell subset into a central memory-like phenotype, enhanced the expression of the co-stimulatory marker CD154 (CD40L) and significantly reduced secretion of IL-10. The exhaustion markers PD-1 and LAG-3 were downregulated on both T cell subsets and phenotypical changes were associated with a balanced T cell metabolism, in particular with a significant decrease of reactive oxygen species (ROS). T cell transfer into a HCT116 spheroid model resulted in a significant reduction of the spheroid viability in presence of an anti-PD-1 antibody combined with LDL^high.

Discussion

Further research needs to be conducted to fully understand the impact of LDL on T cells in tumor immunity and moreover, to also unravel LDL effects on other lymphocytes and myeloid cells for improving anti-PD-1 immunotherapy. The reason for improved response might be a resilient, less exhausted phenotype with balanced ROS levels.

Quantitative increase in T regulatory cells enhances bone remodeling in osteogenesis imperfecta

Osteogenesis imperfecta (OI) is characterized by repeated bone fractures. Recent studies have shown that T lymphocytes and regulatory T cells (Tregs) regulate the functions of osteoclasts and osteoblasts, thus playing a role in bone turnover. We demonstrate an activated effector phenotype and higher secretion of pro-inflammatory cytokines, IFN-γ, and TNF-α in OI peripheral T cells as compared with wild-type (WT). Suppressive Tregs (spleen and thymus) were qualitatively similar, whereas there was a quantitative decrease in OI versus WT. Restoring Treg numbers by systemic transplantation in OI mice resulted in reduced T cell activation and effector cytokine secretion that correlated with significant improvements in tibial trabecular and cortical bone parameters and stiffness of femur, along with increased osteoblast mineralization and decreased osteoclast numbers. Therefore, Tregs can dampen the pro-inflammatory environment and enhance bone remodeling in OI mice. Thus, this study will be helpful in developing future autologous immunotherapy-based treatment modalities for OI.

Perturbing DDR signaling enhances cytotoxic effects of local oncolytic virotherapy and modulates the immune environment in glioma

CAN-2409 is a replication-deficient adenovirus encoding herpes simplex virus (HSV) thymidine kinase (tk) currently in clinical trials for treatment of glioblastoma. The expression of tk in transduced cancer cells results in conversion of the pro-drug ganciclovir into a toxic metabolite causing DNA damage, inducing immunogenic cell death and immune activation. We hypothesize that CAN-2409 combined with DNA-damage-response inhibitors could amplify tumor cell death, resulting in an improved response. We investigated the effects of ATR inhibitor AZD6738 in combination with CAN-2409 in vitro using cytotoxicity, cytokine, and fluorescence-activated cell sorting (FACS) assays in glioma cell lines and in vivo with an orthotopic syngeneic murine glioma model. Tumor immune infiltrates were analyzed by cytometry by time of flight (CyTOF). In vitro, we observed a significant increase in the DNA-damage marker γH2AX and decreased expression of PD-L1, pro-tumorigenic cytokines (interleukin-1β [IL-1β], IL-4), and ligand NKG2D after combination treatment compared with monotherapy or control. In vivo, long-term survival was increased after combination treatment (66.7%) compared with CAN-2409 (50%) and control. In a tumor re-challenge, long-term immunity after combination treatment was not improved. Our results suggest that ATR inhibition could amplify CAN-2409's efficacy in glioblastoma through increased DNA damage while having complex immunological ramifications, warranting further studies to determine the ideal conditions for maximized therapeutic benefit.

Hyaluronan Synthase 3 is Protective After Cardiac Ischemia-Reperfusion by preserving the T cell Response

Dysregulated extracellular matrix (ECM) is a hallmark of adverse cardiac remodeling after myocardial infarction (MI). Previous work from our laboratory suggests that synthesis of the major ECM component hyaluronan (HA) may be beneficial for post-infarct healing. Here, we aimed to investigate the mechanisms of hyaluronan synthase 3 (HAS3) in cardiac healing after MI. Mice with genetic deletion of Has3 (Has3 KO) and wildtype mice (WT) underwent 45 minutes of ischemia with subsequent reperfusion (I/R), followed by monitoring of heart function and analysis of tissue remodeling for up to three weeks. Has3 KO mice exhibited impaired cardiac function as evidenced by a reduced ejection fraction. Accordingly, Has3 deficiency also resulted in an increased scar size. Cardiac fibroblast activation and CD68⁺ macrophage counts were similar between genotypes. However, we found a significant decrease in CD4 T cells in the hearts of Has3 KO mice seven days post-MI, in particular reduced numbers of CD4⁺CXCR3⁺ Th1 and CD4⁺CD25⁺ Treg cells. Furthermore, Has3 deficient cardiac T cells were less activated and more apoptotic as shown by decreased CD69⁺ and increased annexin V⁺ cells, respectively. In vitro assays using activated splenic CD3 T cells demonstrated that Has3 deficiency resulted in reduced expression of the main HA receptor CD44 and diminished T cell proliferation. T cell transendothelial migration was similar between genotypes. Of note, analysis of peripheral blood from patients with ST-elevation myocardial infarction (STEMI) revealed that HAS3 is the predominant HAS isoenzyme also in human T cells. In conclusion, our data suggest that HAS3 is required for mounting a physiological T cell response after MI to support cardiac healing. Therefore, our study may serve as a foundation for the development of novel strategies targeting HA-matrix to preserve T cell function after MI.

T-cell-specific Sel1L deletion exacerbates EAE by promoting Th1/Th17-cell differentiation

Multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) are demyelinating neuroinflammatory diseases identified by the accumulation and aggregation of misfolded proteins in the brain. The Sel1L-Hrd1 complex comprising endoplasmic reticulum associated degradation (ERAD) is an ER-protein quality control system (ERQC) in the cell. Unfortunately, the contribution of ERAD to the development of these diseases has not been well explored. In this study, we used mice with a conditional deletion (KO) of Sel1L in T cells to dissect the role of ERAD on T cells and its contribution to the development of EAE. The results showed that Sel1L KO mice developed more severe EAE than the control wild type (WT) mice. Although, no obvious effects on peripheral T cells in steady state, more CD44-CD25+ double-negative stage 3 (DN3) cells were detected in the thymus. Moreover, Sel1L deficiency promoted the differentiation of Th1 and Th17 cells and upregulated the proliferation and apoptosis of CD4 T cells in vitro. Regarding the mechanism analyzed by RNA sequencing, 437 downregulated genes and 271 upregulated genes were detected in Sel1L deletion CD4 T cells, which covered the activation, proliferation, differentiation and apoptosis of these T cells. Thus, this study declared that the dysfunction of Sel1L in ERAD in T cells exacerbated the severity of EAE and indicated the important role of ERQC in maintaining immune homeostasis in the central nervous system.

The Regulatory-T-Cell Memory Phenotype: What We Know

In immunology, the discovery of regulatory T (Treg) cells was a major breakthrough. Treg cells play a key role in pregnancy maintenance, in the prevention of autoimmune responses, and in the control of all immune responses, including responses to self cells, cancer, infection, and a transplant. It is currently unclear whether Treg cells are capable of long-term memory of an encounter with an antigen. Although the term “immunological memory” usually means an enhanced ability to protect the body from reinfection, the memory of the suppressive activity of Treg cells helps to avoid the state of generalized immunosuppression that may result from the second activation of the immune system. In this review, we would like to discuss the concept of regulatory memory and in which tissues memory Treg cells can perform their functions.

ChGn-2 Plays a Cardioprotective Role in Heart Failure Caused by Acute Pressure Overload

Background Cardiac extracellular matrix is critically involved in cardiac homeostasis, and accumulation of chondroitin sulfate glycosaminoglycans (CS-GAGs) was previously shown to exacerbate heart failure by augmenting inflammation and fibrosis at the chronic phase. However, the mechanism by which CS-GAGs affect cardiac functions remains unclear, especially at the acute phase. Methods and Results We explored a role of CS-GAG in heart failure using mice with target deletion of ChGn-2 (chondroitin sulfate N-acetylgalactosaminyltransferase-2) that elongates CS chains of glycosaminoglycans. Heart failure was induced by transverse aortic constriction in mice. The role of CS-GAG derived from cardiac fibroblasts in cardiomyocyte death was analyzed. Cardiac fibroblasts were subjected to cyclic mechanical stretch that mimics increased workload in the heart. Significant CS-GAGs accumulation was detected in the heart of wild-type mice after transverse aortic constriction, which was substantially reduced in ChGn-2^-/- mice. Loss of ChGn-2 deteriorated the cardiac dysfunction caused by pressure overload, accompanied by augmented cardiac hypertrophy and increased cardiomyocyte apoptosis. Cyclic mechanical stretch increased ChGn-2 expression and enhanced glycosaminoglycan production in cardiac fibroblasts. Conditioned medium derived from the stretched cardiac fibroblasts showed cardioprotective effects, which was abolished by CS-GAGs degradation. We found that CS-GAGs elicits cardioprotective effects via dual pathway; direct pathway through interaction with CD44, and indirect pathway through binding to and activating insulin-like growth factor-1. Conclusions Our data revealed the cardioprotective effects of CS-GAGs; therefore, CS-GAGs may play biphasic role in the development of heart failure; cardioprotective role at acute phase despite its possible unfavorable role in the advanced phase.

Influenza Vaccine Associated with the Gene Expression of T Cell Surface Markers in Human Milk

Background: The function of neonatal T cells is reduced compared to adult T cells. T cells could be transferred to the infants through human milk and compensate for their immature T cells. As the subsets of T cells present in human milk have been incompletely described, this study investigated the association between the maternal factors (influenza vaccine, maternal age, and lactation time), the gene expression of T cell surface markers (cluster of differentiation [CD] and chemokine receptors [CCR]), and the concentrations of T cell-related cytokines in human milk. Materials and Methods: The gene expressions of T cell markers and the concentrations of T cell-related cytokines were determined in milk samples from 16 women. Eight donors received influenza vaccine, and eight were not vaccinated during 2019-2020 for the flu season 2020. Results: For T cell surface markers, the gene expression of CD8A was higher than CD4, CCR6, CD25, CXCR5, CD62L, and CD44 in human milk. CD44 copy gene was lower than CCR7 and CXCR3, while CD4 copy gene was lower than CXCR3 in human milk. Women with influenza vaccine had higher copy genes of CD44, CD8A, CD62L, and CD25 and lower CCR7 copy gene in milk than in women without influenza vaccine. Interleukin-17 concentration in human milk decreased with increasing lactation time. Gene expression of T cell markers and cytokine concentrations varied between lactating women. Conclusions: Although a larger study is needed, it appears that the influenza vaccine is associated with the gene expression of T cell markers in human milk.

Mucosal Vaccination with Cyclic Dinucleotide Adjuvants Induces Effective T Cell Homing and IL-17-Dependent Protection against Mycobacterium tuberculosis Infection

Tuberculosis consistently causes more deaths worldwide annually than any other single pathogen, making new effective vaccines an urgent priority for global public health. Among potential adjuvants, STING-activating cyclic dinucleotides (CDNs) uniquely stimulate a cytosolic sensing pathway activated only by pathogens. Recently, we demonstrated that a CDN-adjuvanted protein subunit vaccine robustly protects against tuberculosis infection in mice. In this study, we delineate the mechanistic basis underlying the efficacy of CDN vaccines for tuberculosis. CDN vaccines elicit CD4 T cells that home to lung parenchyma and penetrate into macrophage lesions in the lung. Although CDNs, like other mucosal vaccines, generate B cell-containing lymphoid structures in the lungs, protection is independent of B cells. Mucosal vaccination with a CDN vaccine induces Th1, Th17, and Th1-Th17 cells, and protection is dependent upon both IL-17 and IFN-γ. Single-cell RNA sequencing experiments reveal that vaccination enhances a metabolic state in Th17 cells reflective of activated effector function and implicate expression of Tnfsf8 (CD153) in vaccine-induced protection. Finally, we demonstrate that simply eliciting Th17 cells via mucosal vaccination with any adjuvant is not sufficient for protection. A vaccine adjuvanted with deacylated monophosphoryl lipid A (MPLA) failed to protect against tuberculosis infection when delivered mucosally, despite eliciting Th17 cells, highlighting the unique promise of CDNs as adjuvants for tuberculosis vaccines.

Primary Tumor Suppression and Systemic Immune Activation of Macrophages through the Sting Pathway in Metastatic Skin Tumor

PURPOSE

Agonists of the stimulator of interferon genes (STING) play a key role in activating the STING pathway by promoting the production of cytokines. In this study, we investigated the antitumor effects and activation of the systemic immune response of treatment with DMXAA (5,6-dimethylxanthenone-4-acetic acid), a STING agonist, in EML4-ALK lung cancer and CT26 colon cancer.

MATERIALS AND METHODS

The abscopal effects of DMXAA in the treatment of metastatic skin nodules were assessed. EML4-ALK lung cancer and CT26 colon cancer models were used to evaluate these effects after DMXAA treatment. To evaluate the expression of macrophages and T cells, we sacrificed the tumor-bearing mice after DMXAA treatment and obtained the formalin-fixed paraffin-embedded (FFPE) tissue and tumor cells. Immunohistochemistry and flow cytometry were performed to analyze the expression of each FFPE and tumor cell.

RESULTS

We observed that highly infiltrating immune cells downstream of the STING pathway had increased levels of chemokines after DMXAA treatment. In addition, the levels of CD80 and CD86 in antigen-presenting cells were significantly increased after STING activation. Furthermore, innate immune activation altered the systemic T cell-mediated immune responses, induced proliferation of macrophages, inhibited tumor growth, and increased numbers of cytotoxic memory T cells. Tumor-specific lymphocytes also increased in number after treatment with DMXAA.

CONCLUSION

The abscopal effect of DMXAA treatment on the skin strongly reduced the spread of EML4-ALK lung cancer and CT26 colon cancer through the STING pathway and induced the presentation of antigens.

A Role for the Bone Marrow Microenvironment in Drug Resistance of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with a poor prognosis and remarkable resistance to chemotherapeutic agents. Understanding resistance mechanisms against currently available drugs helps to recognize the therapeutic obstacles. Various mechanisms of resistance to chemotherapy or targeted inhibitors have been described for AML cells, including a role for the bone marrow niche in both the initiation and persistence of the disease, and in drug resistance of the leukemic stem cell (LSC) population. The BM niche supports LSC survival through direct and indirect interactions among the stromal cells, hematopoietic stem/progenitor cells, and leukemic cells. Additionally, the BM niche mediates changes in metabolic and signal pathway activation due to the acquisition of new mutations or selection and expansion of a minor clone. This review briefly discusses the role of the BM microenvironment and metabolic pathways in resistance to therapy, as discovered through AML clinical studies or cell line and animal models.

Neutrophils promote T-cell activation through the regulated release of CD44-bound Galectin-9 from the cell surface during HIV infection

The interaction of neutrophils with T cells has been the subject of debate and controversies. Previous studies have suggested that neutrophils may suppress or activate T cells. Despite these studies, the interaction between neutrophils and T cells has remained a largely unexplored field. Here, based on our RNA sequencing (RNA-seq) analysis, we found that neutrophils have differential transcriptional and functional profiling depending on the CD4 T-cell count of the HIV-infected individual. In particular, we identified that neutrophils in healthy individuals express surface Galectin-9 (Gal-9), which is down-regulated upon activation, and is consistently down-regulated in HIV-infected individuals. However, down-regulation of Gal-9 was associated with CD4 T-cell count of patients. Unstimulated neutrophils express high levels of surface Gal-9 that is bound to CD44, and, upon stimulation, neutrophils depalmitoylate CD44 and induce its movement out of the lipid raft. This process causes the release of Gal-9 from the surface of neutrophils. In addition, we found that neutrophil-derived exogenous Gal-9 binds to cell surface CD44 on T cells, which promotes LCK activation and subsequently enhances T-cell activation. Furthermore, this process was regulated by glycolysis and can be inhibited by interleukin (IL)-10. Together, our data reveal a novel mechanism of Gal-9 shedding from the surface of neutrophils. This could explain elevated plasma Gal-9 levels in HIV-infected individuals as an underlying mechanism of the well-characterized chronic immune activation in HIV infection. This study provides a novel role for the Gal-9 shedding from neutrophils. We anticipate that our results will spark renewed investigation into the role of neutrophils in T-cell activation in other acute and chronic conditions, as well as improved strategies for modulating Gal-9 shedding.

This study shows that HIV-infected individuals have different neutrophil profiles depending on their CD4 T cell count. In particular, neutrophils express high levels of surface Gal-9 but this is shed upon stimulation; this exogenous Gal-9 binds to CD44 on T cells, which promotes LCK activation and subsequently enhances T cell activation.

Transcriptome analysis of the bursa of Fabricius and thymus of laying ducks reveals immune gene expression changes underlying the impacts of stocking densities

The thymus and bursa of Fabricius are important immune organs in poultry as they play essential roles in sustaining the normal immune function to maintain health. The following trial investigated whether the stocking density affected gene expressions in immune organs.Jinding ducklings were raised in either low or high density (4 or 8 birds/m²) conditions from four to 14 weeks of age, and were then slaughtered and tissues removed. Samples were subjected to high-throughput sequencing to sequence RNA extraction. After filtering calculations with R software, a total of 508 (thymus) and 1,356 (bursa of Fabricius) differentially expressed genes (DEGs) were identified, suggesting that stocking density has an effect on gene expression in duck immune organs.A total of 112 immune factor genes and 112 immune pattern receptor genes in ducks, of which four thymus genes and 18 bursa of Fabricius genes were differentially expressed in ducks, which indicated that the change of stocking density could affect the expression of immune genes in poultry.

Cellular Immunotherapy Targeting Cancer Stem Cells: Preclinical Evidence and Clinical Perspective

The term “cancer stem cells” (CSCs) commonly refers to a subset of tumor cells endowed with stemness features, potentially involved in chemo-resistance and disease relapses. CSCs may present peculiar immunogenic features influencing their homeostasis within the tumor microenvironment. The susceptibility of CSCs to recognition and targeting by the immune system is a relevant issue and matter of investigation, especially considering the multiple emerging immunotherapy strategies. Adoptive cellular immunotherapies, especially those strategies encompassing the genetic redirection with chimeric antigen receptors (CAR), hold relevant promise in several tumor settings and might in theory provide opportunities for selective elimination of CSC subsets. Initial dedicated preclinical studies are supporting the potential targeting of CSCs by cellular immunotherapies, indirect evidence from clinical studies may be derived and new studies are ongoing. Here we review the main issues related to the putative immunogenicity of CSCs, focusing on and highlighting the existing evidence and opportunities for cellular immunotherapy approaches with T and non-T antitumor lymphocytes.

Antigen-driven PD-1+ TOX+ BHLHE40+ and PD-1+ TOX+ EOMES+ T lymphocytes regulate juvenile idiopathic arthritis in situ

T lymphocytes accumulate in inflamed tissues of patients with chronic inflammatory diseases (CIDs) and express pro-inflammatory cytokines upon re-stimulation in vitro. Further, a significant genetic linkage to MHC genes suggests that T lymphocytes play an important role in the pathogenesis of CIDs including juvenile idiopathic arthritis (JIA). However, the functions of T lymphocytes in established disease remain elusive. Here we dissect the transcriptional and the clonal heterogeneity of synovial T lymphocytes in JIA patients by single-cell RNA sequencing combined with T cell receptor profiling on the same cells. We identify clonally expanded subpopulations of T lymphocytes expressing genes reflecting recent activation by antigen in situ. A PD-1⁺ TOX⁺ EOMES⁺ population of CD4⁺ T lymphocytes expressed immune regulatory genes and chemoattractant genes for myeloid cells. A PD-1⁺ TOX⁺ BHLHE40⁺ population of CD4⁺ , and a mirror population of CD8⁺ T lymphocytes expressed genes driving inflammation, and genes supporting B lymphocyte activation in situ. This analysis points out that multiple types of T lymphocytes have to be targeted for therapeutic regeneration of tolerance in arthritis.

Regulation of Intestinal Inflammation by Dietary Fats

With the epidemic of human obesity, dietary fats have increasingly become a focal point of biomedical research. Epidemiological studies indicate that high-fat diets (HFDs), especially those rich in long-chain saturated fatty acids (e.g., Western Diet, National Health Examination survey; NHANES 'What We Eat in America' report) have multi-organ pro-inflammatory effects. Experimental studies have confirmed some of these disease associations, and have begun to elaborate mechanisms of disease induction. However, many of the observed effects from epidemiological studies appear to be an over-simplification of the mechanistic complexity that depends on dynamic interactions between the host, the particular fatty acid, and the rather personalized genetics and variability of the gut microbiota. Of interest, experimental studies have shown that certain saturated fats (e.g., lauric and myristic fatty acid-rich coconut oil) could exert the opposite effect; that is, desirable anti-inflammatory and protective mechanisms promoting gut health by unanticipated pathways. Owing to the experimental advantages of laboratory animals for the study of mechanisms under well-controlled dietary settings, we focus this review on the current understanding of how dietary fatty acids impact intestinal biology. We center this discussion on studies from mice and rats, with validation in cell culture systems or human studies. We provide a scoping overview of the most studied diseases mechanisms associated with the induction or prevention of Inflammatory Bowel Disease in rodent models relevant to Crohn's Disease and Ulcerative Colitis after feeding either high-fat diet (HFD) or feed containing specific fatty acid or other target dietary molecule. Finally, we provide a general outlook on areas that have been largely or scarcely studied, and assess the effects of HFDs on acute and chronic forms of intestinal inflammation.

TNF-a Is a Potent Stimulator of Tc9-Cell Differentiation

Tumor-specific Tc9 cells exhibit an excellent antitumor potential in tumor immunotherapy. Identification of factors that contribute to Tc9-cell differentiation may have important clinical significance. In this study, we found that tumor necrosis factor (TNF)-α promotes Tc9 differentiation in vitro, and the TNF-α-induced Tc9 cells display enhanced cell survival and cell proliferation. More importantly, the TNF-α-induced tumor-specific Tc9 cells have increased antitumor capabilities in vivo. TNF-α activates its downstream signaling through 2 cell surface receptors, TNFR1 and TNFR2. In this study, we found that TNF-α promotes Tc9-cell differentiation through TNFR2, but not TNFR1. Furthermore, we found that TNF-α-TNFR2 activates STAT5 and nuclear factor-κB signaling during Tc9-cell differentiation. Blocking STAT5 or nuclear factor-κB by their specific inhibitors partially abrogates TNF-α-induced promotion of Tc9-cell differentiation. Thus, our study demonstrated TNF-α as a potent stimulator of Tc9-cell differentiation and may have important clinical implications.

CD44 expression in the cuprizone model

Numerous studies report that changes in extracellular matrix components and receptors, such as CD44, contribute to immune cell recruitment and thus lesion formation in multiple sclerosis (MS). In the present study, we used the cuprizone model to elucidate the expression pattern of CD44 in a toxin-induced MS model. Therefore, tissues of cuprizone-intoxicated mice were analyzed by real-time qRT-PCR and immunohistochemical staining against CD44. Co-localization analyses of CD44-positive cells with glial cell markers were performed by immunofluorescence labeling and in-situ hybridization. To investigate the functional importance of CD44 expression for myelination and glial cell activation, Cd44-deficient mice were used. In this study we demonstrate that CD44 expression is induced in a time-dependent manner in an autoimmune-independent model of MS. Up-regulation of CD44 expression was primarily associated to the superficial and perivascular glia limitans and demyelinated white matter structures, particularly the corpus callosum. In the demyelinated corpus callosum, CD44 was localized on GFAP⁺ astrocytes and IBA1⁺ microglial cells. Despite a robust expression induction, Cd44-deficiency did not ameliorate cuprizone-induced pathology. Although further studies will be needed to examine the functional relevance of CD44 in the cuprizone model, the spatial and temporal expression pattern of CD44 will pave the way to evaluate its precise role in different (immune and non-immune) pathological conditions.

Expression of ACAP1 Is Associated with Tumor Immune Infiltration and Clinical Outcome of Ovarian Cancer

ADP-ribosylation factor (Arf) GTPase-activating protein (GAP) with coiled-coil, ankyrin repeat and PH domains 1 (ACAP1) is an Arf6 GAP that regulates membrane trafficking and is critical for the migratory potential of cells. However, the roles of ACAP1 have not been fully explored and its association with clinicopathological features in ovarian cancer is still unknown. In this study, we systematically analyzed multiple databases, including TISIDB, Tumor Immune Estimation Resource (TIMER2.0), Gene Expression Omnibus (GEO), CORTECON, Kaplan-Meier Plotter and LinkedOmics platforms to reveal the clinical significance and function of ACAP1 in ovarian cancer. We found that the expression of ACAP1 was upregulated in ovarian cancer and high ACAP1 expression predicted poor prognosis. Our data demonstrated that the expression and methylation status of ACAP1 were strongly correlated with immune infiltration levels, immunomodulators, and chemokines. Gene set enrichment analysis (GSEA) analysis also showed that the mechanism of ACAP1 in regulating ovarian cancer was related to a variety of immune-related pathways. In addition, we also revealed that the expression of ACAP1 was altered during cell differentiation and associated with cancer cell stemness markers. Our study highlights the clinical significance of ACAP1 in ovarian cancer and provides insight into the novel function of ACAP1 in regulation of tumor immune microenvironment and cancer cell stemness.

Targeting Cancer Stem Cells by Genetically Engineered Chimeric Antigen Receptor T Cells

The term cancer stem cell (CSC) starts 25 years ago with the evidence that CSC is a subpopulation of tumor cells that have renewal ability and can differentiate into several distinct linages. Therefore, CSCs play crucial role in the initiation and the maintenance of cancer. Moreover, it has been proposed throughout several studies that CSCs are behind the failure of the conventional chemo-/radiotherapy as well as cancer recurrence due to their ability to resist the therapy and their ability to re-regenerate. Thus, the need for targeted therapy to eliminate CSCs is crucial; for that reason, chimeric antigen receptor (CAR) T cells has currently been in use with high rate of success in leukemia and, to some degree, in patients with solid tumors. This review outlines the most common CSC populations and their common markers, in particular CD133, CD90, EpCAM, CD44, ALDH, and EGFRVIII, the interaction between CSCs and the immune system, CAR T cell genetic engineering and signaling, CAR T cells in targeting CSCs, and the barriers in using CAR T cells as immunotherapy to treat solid cancers.

Heterogeneity of Stemlike Circulating Tumor Cells in Invasive Breast Cancer

The presence of stem and epithelial–mesenchymal-transition (EMT) features in circulating tumor cells (CTCs) determines their invasiveness, adaptability to the microenvironment, and resistance to proapoptotic signals and chemotherapy. It also allows them to fulfil the role of metastatic “seeds”. We evaluated the heterogeneity of stem CTCs by their CD44, ALDH1, and CD133 expression depending on N-cadherin expression in breast-cancer patients. A total of 38 female patients were selected for this study. CTC phenotypes were determined by flow cytometry before any type of treatment. Multiplex immunofluorescence was used for the evaluation of tumor-cell heterogeneity in primary lesions. In patients who had CD44-CD24- CTCs, a subset of cells with the expression of other stem-cell markers (CD133 and ALDH1) were detected. Expression of CD133 and/or ALDH1 may be associated with expression of N-cadherin: all populations of N-cadherin+ CTCs demonstrate stem features; in the absence of N-cadherin expression, true nonstem (CD44-CD24-CD133-ALDH1-) cells are found. The heterogeneity of stem marker expression in CTCs was observed regardless of N-cadherin expression. In our study, stromal cell-derived factor-1 (SDF-1) receptor expression in CTCs did not depend on stemlike traits, but was instead associated with N-cadherin expression. Subpopulations of tumor cells, detected both in tumors and blood, were identified. Breast cancer was characterized by pronounced interpersonal and intrapersonal heterogeneity of CTCs by the presence and combination of various stem features and N-cadherin expression. To complete the characterization of stemlike features of CTCs, we suggest the simultaneous use of the three stem markers.

Chemical synthesis and immunological evaluation of new generation multivalent anticancer vaccines based on a Tn antigen analogue

Tumor associated carbohydrate antigens (TACAs), such as the Tn antigen, have emerged as key targets for the development of synthetic anticancer vaccines. However, the induction of potent and functional immune responses has been challenging and, in most cases, unsuccessful. Herein, we report the design, synthesis and immunological evaluation in mice of Tn-based vaccine candidates with multivalent presentation of the Tn antigen (up to 16 copies), both in its native serine-linked display (Tn-Ser) and as an oxime-linked Tn analogue (Tn-oxime). The high valent vaccine prototypes were synthesized through a late-stage convergent assembly (Tn-Ser construct) and a versatile divergent strategy (Tn-oxime analogue), using chemoselective click-type chemistry. The hexadecavalent Tn-oxime construct induced robust, Tn-specific humoral and CD4⁺/CD8⁺ cellular responses, with antibodies able to bind the Tn antigen on the MCF7 cancer cell surface. The superior synthetic accessibility and immunological properties of this fully-synthetic vaccine prototype makes it a compelling candidate for further advancement towards safe and effective synthetic anticancer vaccines.

HIV-1-induced cytokines deplete homeostatic innate lymphoid cells and expand TCF7-dependent memory NK cells

Human immunodeficiency virus 1 (HIV-1) infection is associated with heightened inflammation and excess risk of cardiovascular disease, cancer and other complications. These pathologies persist despite antiretroviral therapy. In two independent cohorts, we found that innate lymphoid cells (ILCs) were depleted in the blood and gut of people with HIV-1, even with effective antiretroviral therapy. ILC depletion was associated with neutrophil infiltration of the gut lamina propria, type 1 interferon activation, increased microbial translocation and natural killer (NK) cell skewing towards an inflammatory state, with chromatin structure and phenotype typical of WNT transcription factor TCF7-dependent memory T cells. Cytokines that are elevated during acute HIV-1 infection reproduced the ILC and NK cell abnormalities ex vivo. These results show that inflammatory cytokines associated with HIV-1 infection irreversibly disrupt ILCs. This results in loss of gut epithelial integrity, microbial translocation and memory NK cells with heightened inflammatory potential, and explains the chronic inflammation in people with HIV-1.

Impact of Truncated O-glycans in Gastric-Cancer-Associated CD44v9 Detection

CD44 variant isoforms are often upregulated in cancer and associated with increased aggressive tumor phenotypes. The CD44v9 is one of the major protein splice variant isoforms expressed in human gastrointestinal cancer cells. Immunodetection of CD44 isoforms like CD44v9 in tumor tissue is almost exclusively performed by using specific monoclonal antibodies. However, the structural variability conferred by both the alternative splicing and CD44 protein glycosylation is disregarded. In the present work, we have evaluated the role of O-glycosylation using glycoengineered gastric cancer models in the detection of CD44v9 by monoclonal antibodies. We demonstrated, using different technical approaches, that the presence of immature O-glycan structures, such as Tn and STn, enhance CD44v9 protein detection. These findings can have significant implications in clinical applications mainly at the detection and targeting of this cancer-related CD44v9 isoform and highlight the utmost importance of considering glycan structures in cancer biomarker detection and in therapy targeting.

Double negative T cells, a potential biomarker for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that is a challenge to diagnose and treat. There is an urgent need for biomarkers to help define organ involvement, and more effective therapies. A unique population of T cells, the CD3⁺CD4⁻CD8⁻ (DNeg) cells, is significantly increased in lupus patients. Twenty-seven cases (53%) of pediatric SLE patients had elevated DNeg cells in their peripheral blood, which correlated with kidney function (R² = 0.54). Significant infiltration of DNeg cells was observed in both adult and pediatric lupus kidneys by immunofluorescence. For the first time, this study provides direct evidence that DNeg cells facilitate kidney injury in preclinical 8-week-old MRL/lpr lupus mice. In lupus mice, the increase in DNeg cells tracked with worsening disease and correlated with kidney function (R² = 0.85). Our results show that DNeg cells per se can cause kidney dysfunction, increase in number with increase in disease pathology, and could serve as a potential biomarker.

Investigating Prime-Pull Vaccination through a Combination of Parenteral Vaccination and Intranasal Boosting

Formulation of inhalable delivery systems containing tuberculosis (TB) antigens to target the site of infection (lungs) have been considered for the development of subunit vaccines. Inert delivery systems such as poly (lactic-co-glycolic acid) (PLGA) are an interesting approach due to its approval for human use. However, PLGA suffers hydrolytic degradation when stored in a liquid environment for prolonged time. Therefore, in this study, nano- and microparticles composed of different PLGA copolymers (50:50, 75:25 and 85:15), sucrose (10% w/v) and L-leucine (1% w/v) encapsulating H56 TB vaccine candidate were produced as dried powders. In vitro studies in three macrophage cell lines (MH-S, RAW264.7 and THP-1) showed the ability of these cells to take up the formulated PLGA:H56 particles and process the antigen. An in vivo prime-pull immunisation approach consisting of priming with CAF01:H56 (2 × subcutaneous (s.c.) injection) followed by a mucosal boost with PLGA:H56 (intranasal (i.n.) administration) demonstrated the retention of the immunogenicity of the antigen encapsulated within the lyophilised PLGA delivery system, although no enhancing effect could be observed compared to the administration of antigen alone as a boost. The work here could provide the foundations for the scale independent manufacture of polymer delivery systems encapsulating antigens for inhalation/aerolisation to the lungs.

Functionally Overlapping Variants Control Tuberculosis Susceptibility in Collaborative Cross Mice

The variable outcome of Mycobacterium tuberculosis infection observed in natural populations is difficult to model in genetically homogeneous small-animal models. The newly developed Collaborative Cross (CC) represents a reproducible panel of genetically diverse mice that display a broad range of phenotypic responses to infection. We explored the genetic basis of this variation, focusing on a CC line that is highly susceptible to M. tuberculosis infection. This study identified multiple quantitative trait loci associated with bacterial control and cytokine production, including one that is caused by a novel loss-of-function mutation in the Itgal gene, which is necessary for T cell recruitment to the infected lung. These studies verify the multigenic control of mycobacterial disease in the CC panel, identify genetic loci controlling diverse aspects of pathogenesis, and highlight the utility of the CC resource.

Host genetics plays an important role in determining the outcome of Mycobacterium tuberculosis infection. We previously found that Collaborative Cross (CC) mouse strains differ in their susceptibility to M. tuberculosis and that the CC042/GeniUnc (CC042) strain suffered from a rapidly progressive disease and failed to produce the protective cytokine gamma interferon (IFN-γ) in the lung. Here, we used parallel genetic and immunological approaches to investigate the basis of CC042 mouse susceptibility. Using a population derived from a CC001/Unc (CC001) × CC042 intercross, we mapped four quantitative trait loci (QTL) underlying tuberculosis immunophenotypes (Tip1 to Tip4). These included QTL that were associated with bacterial burden, IFN-γ production following infection, and an IFN-γ-independent mechanism of bacterial control. Further immunological characterization revealed that CC042 animals recruited relatively few antigen-specific T cells to the lung and that these T cells failed to express the integrin alpha L (αL; i.e., CD11a), which contributes to T cell activation and migration. These defects could be explained by a CC042 private variant in the Itgal gene, which encodes CD11a and is found within the Tip2 interval. This 15-bp deletion leads to aberrant mRNA splicing and is predicted to result in a truncated protein product. The Itgal^CC042 genotype was associated with all measured disease traits, indicating that this variant is a major determinant of susceptibility in CC042 mice. The combined effect of functionally distinct Tip variants likely explains the profound susceptibility of CC042 mice and highlights the multigenic nature of tuberculosis control in the Collaborative Cross.

IL-2 Therapy Diminishes Renal Inflammation and the Activity of Kidney-Infiltrating CD4+ T Cells in Murine Lupus Nephritis

An acquired deficiency of interleukin-2 (IL-2) and related disturbances in regulatory T cell (Treg) homeostasis play an important role in the pathogenesis of systemic lupus erythematosus (SLE). Low-dose IL-2 therapy was shown to restore Treg homeostasis in patients with active SLE and its clinical efficacy is currently evaluated in clinical trials. Lupus nephritis (LN), a challenging organ manifestation in SLE, is characterized by the infiltration of pathogenic CD4+ T cells into the inflamed kidney. However, the role of the Treg-IL-2 axis in the pathogenesis of LN and the mode of action of IL-2 therapy in the inflamed kidneys are still poorly understood. Using the (NZB × NZW) F1 mouse model of SLE we studied whether intrarenal Treg are affected by a shortage of IL-2 in comparison with lymphatic organs and whether and how intrarenal T cells and renal inflammation can be influenced by IL-2 therapy. We found that intrarenal Treg show phenotypic signs that are reminiscent of IL-2 deprivation in parallel to a progressive hyperactivity of intrarenal conventional CD4+ T cells (Tcon). Short-term IL-2 treatment of mice with active LN induced an expansion the intrarenal Treg population whereas long-term IL-2 treatment reduced the activity and proliferation of intrarenal Tcon, which was accompanied by a clinical and histological amelioration of LN. The association of these immune pathologies with IL-2 deficiency and their reversibility by IL-2 therapy provides important rationales for an IL-2-based immunotherapy of LN.

IL-27 promotes NK cell effector functions via Maf-Nrf2 pathway during influenza infection

Influenza virus targets epithelial cells in the upper respiratory tract. Natural Killer (NK) cell-mediated early innate defense responses to influenza infection include the killing of infected epithelial cells and generation of anti-viral cytokines including interferon gamma (IFN-γ). To date, it is unclear how the underlying cytokine milieu during infection regulates NK cell effector functions. Our data show during influenza infection myeloid cell-derived IL-27 regulates the early-phase effector functions of NK cells in the bronchioalveolar and lung tissue. Lack of IL-27R (Il27ra^−/−) or IL-27 (Ebi3^−/−) resulted in impaired NK cell effector functions including the generation of anti-viral IFN-γ responses. We identify CD27⁺CD11b⁺ NK cells as the primary subset that expresses IL-27R, which predominantly produces IFN-γ within the upper respiratory tract of the infected mice. IL-27 alone was incapable of altering the effector functions of NK cells. However, IL-27 sensitizes NK cells to augment both in vitro and in vivo responses mediated via the NKG2D receptor. This ‘priming’ function of IL-27 is mediated partly via transcriptional pathways regulated by Mafs and Nrf2 transcriptionally regulating TFAM and CPT1. Our data for the first time establishes a novel role for IL-27 in regulating early-phase effector functions of NK cells during influenza infection.

Differential Cytokine Utilization and Tissue Tropism Results in Distinct Repopulation Kinetics of Naïve vs. Memory T Cells in Mice

Naïve and memory T cells co-exist in the peripheral T cell pool, but the cellular mechanisms that maintain the balance and homeostasis of these two populations remain mostly unclear. To address this question, here, we assessed homeostatic proliferation and repopulation kinetics of adoptively transferred naïve and memory T cells in lymphopenic host mice. We identified distinct kinetics of proliferation and tissue-distribution between naïve and memory donor T cells, which resulted in the occupancy of the peripheral T cell pool by mostly naïve-origin T cells in short term (<1 week), but, in a dramatic reversal, by mostly memory-origin T cells in long term (>4 weeks). To explain this finding, we assessed utilization of the homeostatic cytokines IL-7 and IL-15 by naïve and memory T cells. We found different efficiencies of IL-7 signaling between naïve and memory T cells, where memory T cells expressed larger amounts of IL-7Rα but were significantly less potent in activation of STAT5 that is downstream of IL-7 signaling. Nonetheless, memory T cells were superior in long-term repopulation of the peripheral T cell pool, presumably, because they preferentially migrated into non-lymphoid tissues upon adoptive transfer and additionally utilized tissue IL-15 for rapid expansion. Consequently, co-utilization of IL-7 and IL-15 provides memory T cells a long-term survival advantage. We consider this mechanism important, as it permits the memory T cell population to be maintained in face of constant influx of naïve T cells to the peripheral T cell pool and under competing conditions for survival cytokines.

Precise and Rapid Validation of Candidate Gene by Allele Specific Knockout With CRISPR/Cas9 in Wild Mice

It is a tempting goal to identify causative genes underlying phenotypic differences among inbred strains of mice, which is a huge reservoir of genetic resources to understand mammalian pathophysiology. In particular, the wild-derived mouse strains harbor enormous genetic variations that have been acquired during evolutionary divergence over 100s of 1000s of years. However, validating the genetic variation in non-classical strains was extremely difficult, until the advent of CRISPR/Cas9 genome editing tools. In this study, we first describe a T cell phenotype in both wild-derived PWD/PhJ parental mice and F1 hybrids, from a cross to C57BL/6 (B6) mice, and we isolate a genetic locus on Chr2, using linkage mapping and chromosome substitution mice. Importantly, we validate the identification of the functional gene controlling this T cell phenotype, Cd44, by allele specific knockout of the PWD copy, leaving the B6 copy completely intact. Our experiments using F1 mice with a dominant phenotype, allowed rapid validation of candidate genes by designing sgRNA PAM sequences that only target the DNA of the PWD genome. We obtained 10 animals derived from B6 eggs fertilized with PWD sperm cells which were subjected to microinjection of CRISPR/Cas9 gene targeting machinery. In the newborns of F1 hybrids, 80% (n = 10) had allele specific knockout of the candidate gene Cd44 of PWD origin, and no mice showed mistargeting of the B6 copy. In the resultant allele-specific knockout F1 mice, we observe full recovery of T cell phenotype. Therefore, our study provided a precise and rapid approach to functionally validate genes that could facilitate gene discovery in classic mouse genetics. More importantly, as we succeeded in genetic manipulation of mice, allele specific knockout could provide the possibility to inactivate disease alleles while keeping the normal allele of the gene intact in human cells.

Adipocytes: A Novel Target for IL-15/IL-15Rα Cancer Gene Therapy

IL-15 is a proinflammatory cytokine that plays an essential role in the development and activation of natural killer (NK) cells. Adipose tissue acts as an endocrine organ that secretes cytokines and is an important reservoir for lymphocytes. We hypothesized that activation of the IL-15 signaling in adipose tissue will activate and expand the NK cell population and control tumor growth. We recently developed an adipocyte-targeting recombinant adeno-associated viral (rAAV) vector with minimal off-target transgene expression in the liver. Here, we used this rAAV system to deliver an IL-15/IL-15Rα complex to the abdominal fat by intraperitoneal (i.p.) injection. Adipose IL-15/IL-15Rα complex gene transfer led to the expansion of NK cells in the adipose tissue and spleen in normal mice without notable side effects. The i.p. injection of rAAV-IL-15/IL-15Rα complex significantly suppressed the growth of Lewis lung carcinoma implanted subcutaneously and exerted a significant survival advantage in a B16-F10 melanoma metastasis model. The antitumor effects were associated with the expansion of the NK cells in the blood, spleen, abdominal fat, and tumor, as well as the enhancement of NK cell maturity. Our proof-of-concept preclinical studies demonstrate the safety and efficacy of the adipocyte-specific IL-15/IL-15Rα complex vector as a novel cancer immune gene therapy.

Mass cytometry identifies distinct CD4+ T cell clusters distinguishing HIV-1-infected patients according to antiretroviral therapy initiation

Recent guidelines recommend antiretroviral therapy (ART) to be administered as early as possible during HIV-1 infection. Few studies addressed the immunological benefit of commencing ART during the acute phase of infection. We used mass cytometry to characterize blood CD4+ T cells from HIV-1-infected patients who initiated ART during acute or chronic phase of infection. Using this method, we analyzed a large number of markers on millions of individual immune cells. The results revealed that CD4+ T cell clusters with high expression of CD27, CD28, CD127, and CD44, whose function involves T cell migration to inflamed tissues and survival, are more abundant in healthy controls and patients initiating ART during the acute phase; on the contrary, CD4+ T cell clusters in patients initiating ART during the chronic phase had reduced expression of these markers. The results are suggestive of a better preserved immune function in HIV-1-infected patients initiating ART during acute infection.

TNF-α enhances Th9 cell differentiation and antitumor immunity via TNFR2-dependent pathways

Tumor specific Th9 cells are potential effector cells for adoptive therapy of human cancers. TNF family members OX40L, TL1A and GITRL have been shown to promote the induction of Th9 cells and antitumor immunity. However, the role of TNF-α, the prototype of the TNF superfamily cytokines, in Th9 cell differentiation and their antitumor efficacy is not defined. Here, we showed that TNF-α potently promoted naïve CD4+ T cells to differentiate into Th9 cells in vitro. Furthermore, the addition of TNF-α during Th9 cell differentiation increased T cell survival and proliferation. More importantly, the adoptive transfer of TNF-α-treated Th9 cells induced more potent antitumor effects than regular Th9 cells in mouse tumor model. TNF-α signals via two cell surface receptors, TNFR1 and TNFR2. Mechanistic studies revealed that TNF-α drove Th9 cell differentiation through TNFR2 but not TNFR1. In addition, under Th9 polarizing condition, TNF-α activated STAT5 and NF-κB pathways in T cells in a TNFR2-dependent manner. Inhibition of STAT5 and NF-κB pathways by their specific inhibitors impaired TNF-α-induced Th9 cell differentiation. Our results identified TNF-α as a new powerful inducer of Th9 cells and clarified the molecular mechanisms underlying TNF-α-induced Th9 cell differentiation.

Combination of Sunitinib and PD-L1 Blockade Enhances Anticancer Efficacy of TLR7/8 Agonist-Based Nanovaccine

Cancer vaccines composed of tumor-associated antigens (TAAs) and toll-like receptor (TLR) agonists have shown promising antitumor efficacy in preclinical studies by generating antigen-specific CD8 T cells, but translation of cancer vaccines to the clinic has been limited due to variables responses and development of resistance. The tumor microenvironment deploys various immune escape mechanisms that neutralize CD8 T cell-mediated tumor rejection. Therefore, we hypothesized that modulation of the tumor microenvironment can augment CD8 T cell activation and enhance therapeutic efficacy of cancer vaccines. To accomplish this, we aimed to eliminate immune suppressive cells and block their inhibitory signaling. Combination of the tyrosine kinase inhibitor (TKI) sunitinib with a nanoparticle-based cancer vaccine (nanovaccine) resulted in the reduction of immune-suppressive myeloid-derived suppressive cells (MDSCs) and regulatory T cells (Tregs). Blockade of programmed death-ligand 1 (PD-L1) using anti-PD-L1 antibody was used to reduce CD8 T cell exhaustion. Combination of nanovaccine+sunitinib+PD-L1 antibody treatment reduced PD-L1^high M2 macrophages and MDSCs and upregulated activation of CD8 T cells in the tumor. Nanovaccine+sunitinib+PD-L1 antibody treatment also stimulated antigen-specific CD8 T cell response, which led to improved therapeutic efficacy in MB49 and B16F10 murine tumor models. These results suggest that modulation of tumor microenvironment using sunitinib and PD-L1 blockade can significantly enhance the antitumor efficacy of cancer nanovaccine.