Activation of naïve CD4+ T cells re-tunes STAT1 signaling to deliver unique cytokine responses in memory CD4+ T cells

Phenotypic consequences of logarithmic signaling in MAPK stress response

How cells respond to dynamic environmental changes is crucial for understanding fundamental biological processes and cell physiology. In this study, we developed an experimental and quantitative analytical framework to explore how dynamic stress gradients that change over time regulate cellular volume, signaling activation, and growth phenotypes. Our findings reveal that gradual stress conditions substantially enhance cell growth compared to conventional acute stress. This growth advantage correlates with a minimal reduction in cell volume dependent on the dynamic of stress. We explain the growth phenotype with our finding of a logarithmic signal transduction mechanism in the yeast Mitogen-Activated Protein Kinase (MAPK) osmotic stress response pathway. These insights into the interplay between gradual environments, cell volume change, dynamic cell signaling, and growth, advance our understanding of fundamental cellular processes in gradual stress environments.

T-helper cells flexibility: the possibility of reprogramming T cells fate

Various disciplines cooperate to find novel approaches to cure impaired body functions by repairing, replacing, or regenerating cells, tissues, or organs. The possibility that a stable differentiated cell can reprogram itself opens the door to new therapeutic strategies against a multitude of diseases caused by the loss or dysfunction of essential, irreparable, and specific cells. One approach to cell therapy is to induce reprogramming of adult cells into other functionally active cells. Understanding the factors that cause or contribute to T cell plasticity is not only of clinical importance but also expands the knowledge of the factors that induce cells to differentiate and improves the understanding of normal developmental biology. The present review focuses on the advances in the conversion of peripheral CD4+ T cells, the conditions of their reprogramming, and the methods proposed to control such cell differentiation.

Age-dependent transcriptomic profiles of leukocytes in pediatric population

Immunity at birth is considered immature. Following birth, our immune function is considered to grow and reach maturation over time. To obtain granular information of leukocyte functions and transcriptomic profiles in pediatric cohort, we examined leukocyte profiles in infants, preschool and school children using single cell RNA sequencing of their peripheral blood mononuclear cells (PBMCs). Monocytes and natural killer (NK) cells showed immaturity in infants. Their innate and adaptive immunity was developed by preschool age. Adaptive immune cells showed different maturation patterns. CD4, CD8 naïve T cells and plasma cells continued to mature untill school age. In CD8 naïve T cells, innate immunity was upregulated in infants, in support of our knowledge that they manifests more innate cell-like phenotype soon after birth. Many signaling pathways have been differentially up- and/or down-regulated in infants, preschool and school children. Their contribution to the development of the immune system needs to be delineated.

Interferon regulatory factor 1 (IRF1) inhibits lung endothelial regeneration following inflammation-induced acute lung injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a respiratory condition caused by severe endothelial barrier dysfunction within the lung. In ARDS, excessive inflammation, tissue edema, and immune cell influx prevents endothelial cell regeneration that is crucial in repairing the endothelial barrier. However, little is known about the molecular mechanism that underpin endothelial cell regeneration in ARDS.

METHODS

R-based bioinformatics tools were used to analyze microarray-derived transcription profiles in human lung microvascular endothelial cells (HLMVECs) subjected to non-treatment or lipopolysaccharide (LPS) exposure. We generated endothelial cell-specific interferon regulatory factor 1 (Irf1) knockout (Irf1EC-/-) and Irf1fl/fl control mice for use in an endotoxemic murine model of acute lung injury (ALI). In vitro studies (qPCR, immunoblotting, and ChIP-qPCR) were conducted in mouse lung endothelial cells (MLECs) and HLMVECs. Dual-luciferase promoter reporter assays were performed in HLMVECs.

RESULTS

Bioinformatics analyses identified IRF1 as a key up-regulated gene in HLMVECs post-LPS exposure. Endothelial-specific knockout of Irf1 in ALI mice resulted in enhanced regeneration of lung endothelium, while liposomal delivery of endothelial-specific Irf1 to wild-type ALI mice inhibited lung endothelial regeneration in a leukemia inhibitory factor (Lif)-dependent manner. Mechanistically, we demonstrated that LPS-induced Stat1Ser727 phosphorylation promotes Irf1 transactivation, resulting in downstream up-regulation of Lif that inhibits endothelial cell proliferation.

CONCLUSIONS

These results demonstrate the existence of a p-Stat1Ser727-Irf1-Lif axis that inhibits lung endothelial cell regeneration post-LPS injury. Thus, direct inhibition of IRF1 or LIF may be a promising strategy for enhancing endothelial cell regeneration and improving clinical outcomes in ARDS patients.

The Role of Oxidative Inactivation of Phosphatase PTEN and TCPTP in Fatty Liver Disease

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are becoming increasingly prevalent worldwide. Despite the different etiologies, their spectra and histological feature are similar, from simple steatosis to more advanced stages such as steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Studies including peroxiredoxin knockout models revealed that oxidative stress is crucial in these diseases, which present as consequences of redox imbalance. Protein tyrosine phosphatases (PTPs) are a superfamily of enzymes that are major targets of reactive oxygen species (ROS) because of an oxidation-susceptible nucleophilic cysteine in their active site. Herein, we review the oxidative inactivation of two tumor suppressor PTPs, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and T-cell protein tyrosine phosphatase (TCPTP), and their contribution to the pathogenicity of ALD and NAFLD, respectively. This review might provide a better understanding of the pathogenic mechanisms of these diseases and help develop new therapeutic strategies to treat fatty liver disease.

IL-6-targeted therapies to block the cytokine or its receptor drive distinct alterations in T cell function

Therapeutics that inhibit IL-6 at different points in its signaling pathway are in clinical use, yet whether the immunological effects of these interventions differ based on their molecular target is unknown. We performed short-term interventions in individuals with type 1 diabetes using anti-IL-6 (siltuximab) or anti-IL-6 receptor (IL-6R; tocilizumab) therapies and investigated the impact of this in vivo blockade on T cell fate and function. Immune outcomes were influenced by the target of the therapeutic intervention (IL-6 versus IL-6R) and by peak drug concentration. Tocilizumab reduced ICOS expression on T follicular helper cell populations and T cell receptor-driven (TCR-driven) STAT3 phosphorylation. Siltuximab reversed resistance to Treg-mediated suppression and increased TCR-driven phosphorylated STAT3 and production of IL-10, IL-21, and IL-27 by T effectors. Together, these findings indicate that the context of IL-6 blockade in vivo drives distinct T cell-intrinsic changes that may influence therapeutic outcomes.

Single-cell RNA sequencing analysis of T helper cell differentiation and heterogeneity

Single-cell transcriptomics has emerged as a powerful tool to investigate cells' biological landscape and focus on the expression profile of individual cells. Major advantage of this approach is an analysis of highly complex and heterogeneous cell populations, such as a specific subpopulation of T helper cells that are known to differentiate into distinct subpopulations. The need for distinguishing the specific expression profile is even more important considering the T cell plasticity. However, importantly, the universal pipelines for single-cell analysis are usually not sufficient for every cell type. Here, the aims are to analyze the diversity of T cell phenotypes employing classical in vitro cytokine-mediated differentiation of human T cells isolated from human peripheral blood by single-cell transcriptomic approach with support of labelled antibodies and a comprehensive bioinformatics analysis using combination of Seurat, Nebulosa, GGplot and others. The results showed high expression similarities between Th1 and Th17 phenotype and very distinct Th2 expression profile. In a case of Th2 highly specific marker genes SPINT2, TRIB3 and CST7 were expressed. Overall, our results demonstrate how donor difference, Th plasticity and cell cycle influence the expression profiles of distinct T cell populations. The results could help to better understand the importance of each step of the analysis when working with T cell single-cell data and observe the results in a more practical way by using our analyzed datasets.

Systems Immunology Analyses of STAT1 Gain-of-Function Immune Phenotypes Reveal Heterogeneous Response to IL-6 and Broad Immunometabolic Roles for STAT1

Patients with STAT1 gain-of-function (GOF) pathogenic variants have enhanced or prolonged STAT1 phosphorylation following cytokine stimulation and exhibit increased yet heterogeneous susceptibility to infections, autoimmunity, and cancer. Although disease phenotypes are diverse and other genetic factors contribute, how STAT1 GOF affects cytokine sensitivity and cell biology remains poorly defined. In this study, we analyzed the immune and immunometabolic profiles of two patients with known pathogenic heterozygous STAT1 GOF mutation variants. A systems immunology approach of peripheral blood cells from these patients revealed major changes in multiple immune cell compartments relative to healthy adult and pediatric donors. Although many phenotypes of STAT1 GOF donors were shared, including increased Th1 cells but decreased class-switched B cells and plasmacytoid dendritic cell populations, others were heterogeneous. Mechanistically, hypersensitivity for cytokine-induced STAT1 phosphorylation in memory T cell populations was particularly evident in response to IL-6 in one STAT1 GOF patient. Immune cell metabolism directly influences cell function, and the STAT1 GOF patients shared an immunometabolic phenotype of heightened glucose transporter 1 (GLUT1) and carnitine palmitoyl transferase 1A (CPT1a) expression across multiple immune cell lineages. Interestingly, the metabolic phenotypes of the pediatric STAT1 GOF donors more closely resembled or exceeded those of healthy adult than healthy age-similar pediatric donors, which had low expression of these metabolic markers. These results define new features of STAT1 GOF patients, including a differential hypersensitivity for IL-6 and a shared increase in markers of metabolism in many immune cell types that suggests a role for STAT1 in metabolic regulation of immunity.

IL-6-Driven pSTAT1 Response Is Linked to T Cell Features Implicated in Early Immune Dysregulation

Elevated levels and enhanced sensing of the pro-inflammatory cytokine interleukin-6 (IL-6) are key features of many autoimmune and inflammatory diseases. To better understand how IL-6 signaling may influence human T cell fate, we investigated the relationships between levels of components of the IL-6R complex, pSTAT responses, and transcriptomic and translational changes in CD4+ and CD8+ T cell subsets from healthy individuals after exposure to IL-6. Our findings highlight the striking heterogeneity in mbIL-6R and gp130 expression and IL-6-driven pSTAT1/3 responses across T cell subsets. Increased mbIL-6R expression correlated with enhanced signaling via pSTAT1 with less impact on pSTAT3, most strikingly in CD4+ naïve T cells. Additionally, IL-6 rapidly induced expression of transcription factors and surface receptors expressed by T follicular helper cells and altered expression of markers of apoptosis. Importantly, many of the features associated with the level of mbIL-6R expression on T cells were recapitulated both in the setting of tocilizumab therapy and when comparing donor CD4+ T cells harboring the genetic variant, IL6R Asp358Ala (rs2228145), known to alter mbIL-6R expression on T cells. Collectively, these findings should be taken into account as we consider the role of IL-6 in disease pathogenesis and translating IL-6 biology into effective therapies for T cell-mediated autoimmune disease.

Age-associated B cells contribute to the pathogenesis of rheumatoid arthritis by inducing activation of fibroblast-like synoviocytes via TNF-α-mediated ERK1/2 and JAK-STAT1 pathways

OBJECTIVES

Age-associated B cells (ABCs) are a recently identified B cell subset, whose expansion has been increasingly linked to the pathogenesis of autoimmune disorders. This study aimed to investigate whether ABCs are involved in the pathogenesis and underlying mechanisms of rheumatoid arthritis (RA).

METHODS

ABCs were assessed in collagen-induced arthritis (CIA) mice and patients with RA using flow cytometry. Transcriptomic features of RA ABCs were explored using RNA-seq. Primary fibroblast-like synoviocytes (FLS) derived from the synovial tissue of patients with RA were cocultured with ABCs or ABCs-conditioned medium (ABCsCM). IL-6, MMP-1, MMP-3 and MMP-13 levels in the coculture supernatant were detected by ELISA. Signalling pathways related to ABCs-induced FLS activation were examined using western blotting.

RESULTS

Increased ABCs levels in the blood, spleen and inflammatory joints of CIA mice were observed. Notably, ABCs were elevated in the blood, synovial fluid and synovial tissue of patients with RA and positively correlated with disease activity. RNA-seq revealed upregulated chemotaxis-related genes in RA ABCs compared with those in naive and memory B cells. Coculture of FLS with RA ABCs or ABCsCM led to an active phenotype of FLS, with increased production of IL-6, MMP-1, MMP-3 and MMP-13. Mechanistically, ABCsCM-derived TNF-α promoted the upregulation of interferon-stimulated genes in FLS, with elevated phosphorylation of ERK1/2 and STAT1. Furthermore, blockage of ERK1/2 and Janus Kinase (JAK)-STAT1 pathways inhibited the activation of FLS induced by ABCsCM.

CONCLUSIONS

Our results suggest that ABCs contribute to the pathogenesis of RA by inducing the activation of FLS via TNF-α-mediated ERK1/2 and JAK-STAT1 pathways.

Interferons limit autoantigen-specific CD8+ T-cell expansion in the non-obese diabetic mouse

Interferon gamma (IFNγ) is a proinflammatory cytokine implicated in autoimmune diseases. However, deficiency or neutralization of IFNγ is ineffective in reducing disease. We characterize islet antigen-specific T cells in non-obese diabetic (NOD) mice lacking all three IFN receptor genes. Diabetes is minimally affected, but at 125 days of age, antigen-specific CD8⁺ T cells, quantified using major histocompatibility complex class I tetramers, are present in 10-fold greater numbers in Ifngr-mutant NOD mice. T cells from Ifngr-mutant mice have increased proliferative responses to interleukin-2 (IL-2). They also have reduced phosphorylated STAT1 and its target gene, suppressor of cytokine signaling 1 (SOCS-1). IFNγ controls the expansion of antigen-specific CD8⁺ T cells by mechanisms which include increased SOCS-1 expression that regulates IL-2 signaling. The expanded CD8⁺ T cells are likely to contribute to normal diabetes progression despite reduced inflammation in Ifngr-mutant mice.

Making sense of IL-6 signalling cues in pathophysiology

Unravelling the molecular mechanisms that account for functional pleiotropy is a major challenge for researchers in cytokine biology. Cytokine-receptor cross-reactivity and shared signalling pathways are considered primary drivers of cytokine pleiotropy. However, reports epitomized by studies of Jak-STAT cytokine signalling identify interesting biochemical and epigenetic determinants of transcription factor regulation that affect the delivery of signal-dependent cytokine responses. Here, a regulatory interplay between STAT transcription factors and their convergence to specific genomic enhancers support the fine-tuning of cytokine responses controlling host immunity, functional identity, and tissue homeostasis and repair. In this review, we provide an overview of the signalling networks that shape the way cells sense and interpret cytokine cues. With an emphasis on the biology of interleukin-6, we highlight the importance of these mechanisms to both physiological processes and pathophysiological outcomes.

Impaired JAK-STAT pathway signaling in leukocytes of the frail elderly

Background

Elderly often show reduced immune functioning and can develop chronic low-grade inflammation. Why some elderly are more prone to become frail is unknown. We investigated whether frailty is associated with altered cytokine signaling through the JAK-STAT pathway in leukocytes of 34 individuals aged 65–74 years. In addition, we investigated how this relation is affected by chronic low-grade inflammation during the previous 20 years. Cytokine signaling was quantified by measuring intracellular STAT1, STAT3, and STAT5 phosphorylation in monocytes, B cells, CD4⁺ T cells and CD8⁺ T cells upon stimulation with IL-2, IL-6, IL-10, IFNα and IFNγ, using phospho-flow cytometry. Presence of chronic low-grade inflammation was investigated by evaluating 18 different plasma inflammatory markers that had been measured repeatedly in the same individuals over the previous 20 years. Frailty was assessed as a score on a frailty index.

Results

We found that lower cytokine-induced pSTAT responsiveness in the various cell subsets was seen with higher frailty scores in both men and women, indicative of dysfunctional pSTAT responses in frailer individuals. Associations differed between men and women, with frailer women showing lower pSTAT1 responses in monocytes and frailer men showing lower pSTAT5 responses in CD4⁺ and CD8⁺ T cells. Notably, lower IL-10-induced pSTAT3 responses in men were related to both higher frailty scores and higher CRP levels over the past 20 years. This might indicate poor resolution of low-grade inflammation due to defective regulatory pSTAT signaling in older men.

Conclusions

Our results emphasize the importance of preserved JAK-STAT pathway signaling in healthy aging and reveal cellular pSTAT levels as a candidate biomarker of frailty.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-021-00261-w.

Unravelling the broader complexity of IL-6 involvement in health and disease

The classification of interleukin-6 (IL-6) as a pro-inflammatory cytokine undervalues the biological impact of this cytokine in health and disease. With broad activities affecting the immune system, tissue homeostasis and metabolic processes, IL-6 displays complex biology. The significance of these involvements has become increasingly important in clinical settings where IL-6 is identified as a prominent target for therapy. Here, clinical experience with IL-6 antagonists emphasises the need to understand the context-dependent properties of IL-6 within an inflammatory environment and the anticipated or unexpected consequences of IL-6 blockade. In this review, we will describe the immunobiology of IL-6 and explore the gamut of IL-6 bioactivity affecting the clinical response to biological drugs targeting this cytokine pathway.

Emerging roles for IL-6 family cytokines as positive and negative regulators of ectopic lymphoid structures

IL-6 family cytokines display broad effects in haematopoietic and non-haematopoietic cells that regulate immune homeostasis, host defence, haematopoiesis, development, reproduction and wound healing. Dysregulation of these activities places this cytokine family as important mediators of autoimmunity, chronic inflammation and cancer. In this regard, ectopic lymphoid structures (ELS) are a pathological hallmark of many tissues affected by chronic disease. These inducible lymphoid aggregates form compartmentalised T cell and B cell zones, germinal centres, follicular dendritic cell networks and high endothelial venules, which are defining qualities of peripheral lymphoid organs. Accordingly, ELS can support local antigen-specific responses to self-antigens, alloantigens, pathogens and tumours. ELS often correlate with severe disease progression in autoimmune conditions, while tumour-associated ELS are associated with enhanced anti-tumour immunity and a favourable prognosis in cancer. Here, we discuss emerging roles for IL-6 family cytokines as regulators of ELS development, maintenance and activity and consider how modulation of these activities has the potential to aid the successful treatment of autoimmune conditions and cancers where ELS feature.

Role of IL-6 in the commitment of T cell subsets

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IL-6 is a non-redundant differentiation factor for Th17 cells and Tfh cells.

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The induction of ROR-γt⁺ Treg cells in the lamina propria depends on IL-6.

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Generation of distinct T helper cell subsets might depend on different IL-6 signaling modalities.

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IL-6-directed therapies must consider the disease-relevant IL-6 signaling modality.

IL-6 gained much attention with the discovery that this cytokine is a non-redundant differentiation factor for Th17 cells and T follicular helper cells. Adaptive immune responses to fungi and extracellular bacteria are impaired in the absence of IL-6. IL-6 is also required for the induction of ROR-γt⁺ Treg cells, which are gatekeepers of homeostasis in the gut lamina propria in the presence of commensal bacteria. Conversely, severe immunopathology in T cell-mediated autoimmunity is mediated by Th17 cells that rely on IL-6 for their generation and maintenance. Recently, it has been discovered that the differentiation of these distinct T helper cell subsets may be linked to distinct signaling modalities of IL-6. Here, we summarize the current knowledge on the mode of action of IL-6 in the differentiation and maintenance of T cell subsets and propose that a context-dependent understanding of the impact of IL-6 on T cell subsets might inform rational IL-6-directed interventions in autoimmunity and chronic inflammation.

T Cell Protein Tyrosine Phosphatase in Glucose Metabolism

T cell protein tyrosine phosphatase (TCPTP), a vital regulator in glucose metabolism, inflammatory responses, and tumor processes, is increasingly considered a promising target for disease treatments and illness control. This review discusses the structure, substrates and main biological functions of TCPTP, as well as its regulatory effect in glucose metabolism, as an attempt to be referenced for formulating treatment strategies of metabolic disorders. Given the complicated regulation functions in different tissues and organs of TCPTP, the development of drugs inhibiting TCPTP with a higher specificity and a better biocompatibility is recognized as a promising therapeutic strategy for diabetes or obesity. Besides, treatments targeting TCPTP in a specific tissue or organ are suggested to be considerably promising.

Competitive binding of STATs to receptor phospho-Tyr motifs accounts for altered cytokine responses

Cytokines elicit pleiotropic and non-redundant activities despite strong overlap in their usage of receptors, JAKs and STATs molecules. We use IL-6 and IL-27 to ask how two cytokines activating the same signaling pathway have different biological roles. We found that IL-27 induces more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modeling of IL-6 and IL-27 signaling identified STAT3 binding to GP130, and STAT1 binding to IL-27Rα, as the main dynamical processes contributing to sustained pSTAT1 levels by IL-27. Mutation of Tyr613 on IL-27Rα decreased IL-27-induced STAT1 phosphorylation by 80% but had limited effect on STAT3 phosphorgylation. Strong receptor/STAT coupling by IL-27 initiated a unique gene expression program, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in patients with systemic lupus erythematosus (SLE). IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which correlated with higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib specifically lowered the levels of STAT1 activation by IL-6. Our data show that receptor and STATs concentrations critically contribute to shape cytokine responses and generate functional pleiotropy in health and disease.

Diverse Cell Stimulation Kinetics Identify Predictive Signal Transduction Models

Computationally understanding the molecular mechanisms that give rise to cell signaling responses upon different environmental, chemical, and genetic perturbations is a long-standing challenge that requires models that fit and predict quantitative responses for new biological conditions. Overcoming this challenge depends not only on good models and detailed experimental data but also on the rigorous integration of both. We propose a quantitative framework to perturb and model generic signaling networks using multiple and diverse changing environments (hereafter "kinetic stimulations") resulting in distinct pathway activation dynamics. We demonstrate that utilizing multiple diverse kinetic stimulations better constrains model parameters and enables predictions of signaling dynamics that would be impossible using traditional dose-response or individual kinetic stimulations. To demonstrate our approach, we use experimentally identified models to predict signaling dynamics in normal, mutated, and drug-treated conditions upon multitudes of kinetic stimulations and quantify which proteins and reaction rates are most sensitive to which extracellular stimulations.

NG-Circos: next-generation Circos for data visualization and interpretation

Circos plots are widely used to display multi-dimensional next-generation genomic data, but existing implementations of Circos are not interactive with limited support of data types. Here, we developed next-generation Circos (NG-Circos), a flexible JavaScript-based circular genome visualization tool for designing highly interactive Circos plots using 21 functional modules with various data types. To our knowledge, NG-Circos is the most powerful software to construct interactive Circos plots. By supporting diverse data types in a dynamic browser interface, NG-Circos will accelerate the next-generation data visualization and interpretation, thus promoting the reproducible research in biomedical sciences and beyond. NG-Circos is available at https://wlcb.oit.uci.edu/NG-Circos and https://github.com/YaCui/NG-Circos.

Noncanonical STAT3 activity sustains pathogenic Th17 proliferation and cytokine response to antigen

The STAT3 signaling pathway is required for early Th17 cell development, and therapies targeting this pathway are used for autoimmune disease. However, the role of STAT3 in maintaining inflammatory effector Th17 cell function has been unexplored. Th17ΔSTAT3 mice, which delete STAT3 in effector Th17 cells, were resistant to experimental autoimmune encephalomyelitis (EAE), a murine model of MS. Th17 cell numbers declined after STAT3 deletion, corresponding to reduced cell cycle. Th17ΔSTAT3 cells had increased IL-6-mediated phosphorylation of STAT1, known to have antiproliferative functions. Th17ΔSTAT3 cells also had reduced mitochondrial membrane potential, which can regulate intracellular Ca2+. Accordingly, Th17ΔSTAT3 cells had reduced production of proinflammatory cytokines when stimulated with myelin antigen but normal production of cytokines when TCR-induced Ca2+ flux was bypassed with ionomycin. Thus, early transcriptional roles of STAT3 in developing Th17 cells are later complimented by noncanonical STAT3 functions that sustain pathogenic Th17 cell proliferation and cytokine production.

Complex human adenoid tissue-based ex vivo culture systems reveal anti-inflammatory drug effects on germinal center T and B cells

BACKGROUND

Human immunology research is often limited to peripheral blood. However, there are important differences between blood immune cells and their counterparts residing in secondary lymphoid organs, such as in the case of germinal center (GC) T follicular helper (Tfh) cells and GC B cells.

METHODS

We developed a versatile ex vivo lymphoid organ culture platform that is based on human pharyngeal tonsils (adenoids) and allows for drug testing. We systematically phenotyped Tfh and GC B cell subsets in explant- and suspension cultures using multicolor flow cytometry and cytokine multiplex analysis.

FINDINGS

Phenotypic changes of certain ex vivo cultured immune cell subsets could be modulated by cytokine addition. Furthermore, we optimized an activation-induced marker assay to evaluate the response to T cell stimulation. We provide proof-of-concept that Tfh and GC B cells could be modulated in these cultures by different anti-inflammatory drugs in unstimulated states and upon activation with vaccine-derived antigens. For example, GC B cells were lost upon CD40L blockade, and clinically approved JAK inhibitors impacted Tfh and GC B cells, including down-regulation of their key transcription factor BCL6. BCL6 regulation was affected by IL-6 signaling in T cells and IL-4 in B cells, respectively. Furthermore, we demonstrated that JAK signaling and TNF signaling contributed to the stimulation-induced activation of tonsil-derived T cells.

INTERPRETATION

Our optimized methods, assays, and mechanistic findings can contribute to a better understanding of human GC responses. These insights may be relevant for improving autoimmune disease therapy and vaccination efficacy.

FUNDING

This work was supported by a project grant under the joint research cooperation agreement of LMU Munich, LMU University Hospital, and Sanofi-Aventis Deutschland GmbH, as well as by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Emmy Noether Programme BA 5132/1-1 and BA 5132/1-2 (252623821), SFB 1054 Project B12 (210592381), and SFB 914 Project B03 (165054336).

ADAM17 Activity and IL-6 Trans-Signaling in Inflammation and Cancer

All ligands of the epidermal growth factor receptor (EGF-R) are transmembrane proteins, which need to be proteolytically cleaved in order to be systemically active. The major protease responsible for this cleavage is the membrane metalloprotease ADAM17, which also has been implicated in cleavage of TNFα and interleukin-6 (IL-6) receptor. It has been recently shown that in the absence of ADAM17, the main protease for EGF-R ligand processing, colon cancer formation is largely abrogated. Intriguingly, colon cancer formation depends on EGF-R activity on myeloid cells rather than on intestinal epithelial cells. A major activity of EGF-R on myeloid cells is the stimulation of IL-6 synthesis. Subsequently, IL-6 together with the ADAM17 shed soluble IL-6 receptor acts on intestinal epithelial cells via IL-6 trans-signaling to induce colon cancer formation, which can be blocked by the inhibitor of IL-6 trans-signaling, sgp130Fc. Blockade of IL-6 trans-signaling therefore offers a new therapeutic window downstream of the EGF-R for the treatment of colon cancer and possibly of other EGF-R related neoplastic diseases.

HLA-Class II Artificial Antigen Presenting Cells in CD4+ T Cell-Based Immunotherapy

CD4+ T cells differentiate into various T helper subsets characterized by distinct cytokine secreting profiles that confer them effector functions adapted to a variety of infectious or endogenous threats. Regulatory CD4+ T cells are another specialized subset that plays a fundamental role in the maintenance of immune tolerance to self-antigens. Manipulating effector or regulatory CD4+ T cells responses is a promising immunotherapy strategy for, respectively, chronical viral infections and cancer, or severe autoimmune diseases and transplantation. Adoptive cell therapy (ACT) is an emerging approach that necessitates defining robust and efficient methods for the in vitro expansion of antigen-specific T cells then infused into patients. To address this challenge, artificial antigen presenting cells (AAPCs) have been developed. They constitute a reliable and easily usable platform to stimulate and amplify antigen-specific CD4+ T cells. Here, we review the recent advances in understanding the functions of CD4+ T cells in immunity and in immune tolerance, and their use for ACT. We also describe the characteristics of different AAPC models and the way to improve their stimulating functions. Finally, we discuss the potential interest of these AAPCs, both as fundamental tools to decipher CD4+ T cell responses and as reagents to generate clinical grade antigen-specific CD4+ T cells for immunotherapy.