Regulation of interferon and Toll-like receptor signaling during macrophage activation by opposing feedforward and feedback inhibition mechanisms

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

Nuclear ADP-ribosylation drives IFNγ-dependent STAT1α enhancer formation in macrophages

STAT1α is a key transcription factor driving pro-inflammatory responses in macrophages. We found that the interferon gamma (IFNγ)-regulated transcriptional program in macrophages is controlled by ADP-ribosylation (ADPRylation) of STAT1α, a post-translational modification resulting in the site-specific covalent attachment of ADP-ribose moieties. PARP-1, the major nuclear poly(ADP-ribose) polymerase (PARP), supports IFNγ-stimulated enhancer formation by regulating the genome-wide binding and IFNγ-dependent transcriptional activation of STAT1α. It does so by ADPRylating STAT1α on specific residues in its DNA-binding domain (DBD) and transcription activation (TA) domain. ADPRylation of the DBD controls STAT1α binding to its cognate DNA elements, whereas ADPRylation of the TA domain regulates enhancer activation by modulating STAT1α phosphorylation and p300 acetyltransferase activity. Loss of ADPRylation at either site leads to diminished IFNγ-dependent transcription and downstream pro-inflammatory responses. We conclude that PARP-1-mediated ADPRylation of STAT1α drives distinct enhancer activation mechanisms and is a critical regulator of inflammatory responses in macrophages.

The Effects of Oral Liposomal Glutathione and In Vitro Everolimus in Altering the Immune Responses against Mycobacterium bovis BCG Strain in Individuals with Type 2 Diabetes

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tb) still remains a devastating infectious disease in the world. There has been a daunting increase in the incidence of Type 2 Diabetes Mellitus (T2DM) worldwide. T2DM patients are three times more vulnerable to M. tb infection compared to healthy individuals. TB-T2DM coincidence is a challenge for global health control. Despite some progress in the research, M. tb still has unexplored characteristics in successfully evading host defenses. The lengthy duration of treatment, the emergence of multi-drug-resistant strains and extensive-drug-resistant strains of M. tb have made TB treatment very challenging. Previously, we have tested the antimycobacterial effects of everolimus within in vitro granulomas generated from immune cells derived from peripheral blood of healthy subjects. However, the effectiveness of everolimus treatment against mycobacterial infection in individuals with T2DM is unknown. Furthermore, the effectiveness of the combination of in vivo glutathione (GSH) supplementation in individuals with T2DM along with in vitro treatment of isolated immune cells with everolimus against mycobacterial infection has never been tested. Therefore, we postulated that liposomal glutathione (L-GSH) and everolimus would offer great hope for developing adjunctive therapy for mycobacterial infection. L-GSH or placebo was administered to T2DM individuals orally for three months. Study subjects’ blood was drawn pre- and post- L-GSH/ or placebo supplementation, where Peripheral Blood Mononuclear Cells (PBMCs) were isolated from whole blood to conduct in vitro studies with everolimus. We found that in vitro treatment with everolimus, an mTOR (membrane target of rapamycin) inhibitor, significantly reduced intracellular M. bovis BCG infection alone and in conjunction with L-GSH supplementation. Furthermore, we found L-GSH supplementation coupled with in vitro everolimus treatment produced a greater effect in inhibiting the growth of intracellular Mycobacterium bovis BCG, than with the everolimus treatment alone. We also demonstrated the functions of L-GSH along with in vitro everolimus treatment in modulating the levels of cytokines such as IFN-γ, TNF-α, and IL-2 and IL-6, in favor of improving control of the mycobacterial infection. In summary, in vitro everolimus-treatment alone and in combination with oral L-GSH supplementation for three months in individuals with T2DM, was able to increase the levels of T-helper type 1 (Th1) cytokines IFN-γ, TNF-α, and IL-2 as well as enhance the abilities of granulomas from individuals with T2DM to improve control of a mycobacterial infection.

Preconditioning increases brain resistance against acute brain injury via neuroinflammation modulation

Acute brain injury (ABI) is a broad concept mainly comprised of sudden parenchymal brain injury. Acute brain injury outcomes are dependent not only on the severity of the primary injury, but the delayed secondary injury that subsequently follows as well. These are both taken into consideration when determining the patient's prognosis. Growing clinical and experimental evidence demonstrates that "preconditioning," a prophylactic approach in which the brain is exposed to various pre-injury stressors, can induce varying degrees of "tolerance" against the impact of the ABI by modulating neuroinflammation. In this review, we will summarize the pathophysiology of ABI, and discuss the involved mechanisms of neuroinflammation in ABI, as well as existing experimental and clinical studies demonstrating the efficacy of preconditioning methods in various types of ABI by modulating neuroinflammation.

Type I and II Interferons in the Anti-Tumor Immune Response

The interferons (IFNs) are essential components of the immune response against infections and malignancies. IFNs are potent promoters of the anti-tumor response, but there is also evidence that feedback mechanisms regulated by IFNs negatively control immune responses to avoid hyper-activation and limit inflammation. This balance of responses plays an important role in cancer surveillance, immunoediting and response to anticancer therapeutic approaches. Here we review the roles of both type I and type II IFNs on the control of the immune response against malignancies in the context of effects on both malignant cells and cells of the immune system in the tumor microenvironment.

The Role of MSC Therapy in Attenuating the Damaging Effects of the Cytokine Storm Induced by COVID-19 on the Heart and Cardiovascular System

The global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) has led to 47 m infected cases and 1. 2 m (2.6%) deaths. A hallmark of more severe cases of SARS-CoV-2 in patients with acute respiratory distress syndrome (ARDS) appears to be a virally-induced over-activation or unregulated response of the immune system, termed a "cytokine storm," featuring elevated levels of pro-inflammatory cytokines such as IL-2, IL-6, IL-7, IL-22, CXCL10, and TNFα. Whilst the lungs are the primary site of infection for SARS-CoV-2, in more severe cases its effects can be detected in multiple organ systems. Indeed, many COVID-19 positive patients develop cardiovascular complications, such as myocardial injury, myocarditis, cardiac arrhythmia, and thromboembolism, which are associated with higher mortality. Drug and cell therapies targeting immunosuppression have been suggested to help combat the cytokine storm. In particular, mesenchymal stromal cells (MSCs), owing to their powerful immunomodulatory ability, have shown promise in early clinical studies to avoid, prevent or attenuate the cytokine storm. In this review, we will discuss the mechanistic underpinnings of the cytokine storm on the cardiovascular system, and how MSCs potentially attenuate the damage caused by the cytokine storm induced by COVID-19. We will also address how MSC transplantation could alleviate the long-term complications seen in some COVID-19 patients, such as improving tissue repair and regeneration.

MLLT6 maintains PD-L1 expression and mediates tumor immune resistance

Tumor cells subvert immune surveillance by harnessing signals from immune checkpoints to acquire immune resistance. The protein PD‐L1 is an important component in this process, and inhibition of PD‐L1 elicits durable anti‐tumor responses in a broad spectrum of cancers. However, immune checkpoint inhibition that target known pathways is not universally effective. A better understanding of the genetic repertoire underlying these processes is necessary to expand our knowledge in tumor immunity and to facilitate identification of alternative targets. Here, we present a CRISPR/Cas9 screen in human cancer cells to identify genes that confer tumors with the ability to evade the cytotoxic effects of the immune system. We show that the transcriptional regulator MLLT6 (AF17) is required for efficient PD‐L1 protein expression and cell surface presentation in cancer cells. MLLT6 depletion alleviates suppression of CD8⁺ cytotoxic T cell‐mediated cytolysis. Furthermore, cancer cells lacking MLLT6 exhibit impaired STAT1 signaling and are insensitive to interferon‐γ‐induced stimulation of IDO1, GBP5, CD74, and MHC class II genes. Collectively, our findings establish MLLT6 as a regulator of oncogenic and interferon‐γ‐associated immune resistance.

Galectin-1 Facilitates Macrophage Reprogramming and Resolution of Inflammation Through IFN-β

During the resolution of acute inflammation, macrophages undergo reprogramming from pro-inflammatory, to anti-inflammatory/reparative, and eventually to pro-resolving macrophages. Galectin-1 (Gal-1) is a bona fide pro-resolving lectin while interferon β (IFN-β) was recently shown to facilitate macrophage reprogramming and resolution of inflammation. In this study, we found Gal-1^null mice exhibit a hyperinflammatory phenotype during the resolution of zymosan A-induced peritonitis but not during the early inflammatory response. This phenotype was characterized by reduced macrophage numbers, increased secretion of pro-inflammatory cytokines, such as interleukin-12 (IL-12), and reduced secretion of anti-inflammatory cytokines, such as interleukin-10 (IL-10). In addition, we found a delayed expression of the pro-resolving enzyme 12/15-lipoxygenase in macrophages and heightened levels of the inflammatory protease proteinase-3 (PR3) in peritoneal fluids from Gal-1^null mice. Moreover, we observed sex-dependent differences in the inflammatory profile of Gal-1^null mice. Notably, we found that IFN-β levels were reduced in resolution-phase exudates from Gal-1^null mice. Administration of IFN-β in vivo or ex vivo treatment was able to rescue, at least in part, the hyperinflammatory profile of Gal-1^null mice. In particular, IFN-β recovered a subset of F4/80⁺GR-1⁺ macrophages, restored IL-12 and IL-10 secretion from macrophages to WT values and diminished abnormal peritoneal PR3 levels in Gal-1^null mice. In conclusion, our results revealed a new Gal-1-IFN-β axis that facilitates the resolution of inflammation and might restrain uncontrolled inflammatory disorders.

Abrogating doxorubicin-induced chemobrain by immunomodulators IFN-beta 1a or infliximab: Insights to neuroimmune mechanistic hallmarks

Chemobrain is a well-established clinical syndrome that impairs patient's daily function, in particular attentiveness, coordination and multi-tasking. Thus, it interferes with patient's quality of life. The putative pharmacological intervention against chemobrain relies on understanding the molecular mechanisms underlying it. This study aimed to examine the potential neuroprotective effects of two immunomodulators: Interferon-β-1a (IFN-β-1a), as well as Tumor necrosis function-alpha (TNF-α) inhibitor; Infliximab in doxorubicin (DOX)-induced chemobrain in rats. Besides, the current study targets investigating the possible molecular mechanisms in terms of neuromodulation and interference with different death routes controlling neural homeostasis. Herein, the two immunomodulators IFN-β-1a at a dose of 300,000 units; s.c.three times per week, or Infliximab at a dose of 5 mg/kg/week; i.p. once per week were examined against DOX (2 mg/kg/w, i.p.) once per week for 4 consecutive weeks in rats.The consequent behavioral tests and markers for cognitive impairment, oxidative stress, neuroinflammation, apoptosis and neurobiological abnormalities were further evaluated. Briefly, IFN-β-1a or Infliximab significantly protected against DOX-induced chemobrain. IFN-β-1a or Infliximab ameliorated DOX-induced hippocampal histopathological neurodegenerative changes, halted DOX-induced cognitive impairment, abrogated DOX-induced mitochondrial oxidative, inflammatory and apoptotic stress, mitigated DOX-induced autophagic dysfunction and finally upregulated the mitophagic machineries. In conclusion, these findings suggest that either IFN-β-1a or Infliximab offers neuroprotection against DOX-induced chemobrain which could be explained by their antioxidant, anti-inflammatory, pro-autophagic, pro-mitophagic and antiapoptotic effects. Future clinical studies are recommended to personalize either use of IFN-β-1a or infliximab to ameliorate DOX-induced chemobrain.

Unsaturated polyurethane films grafted with enantiomeric polylysine promotes macrophage polarization to a M2 phenotype through PI3K/Akt1/mTOR axis

The immune system responds immediately to tissue trauma and to biomaterial implants under the participation of M1/M2 macrophages polarization. The surface properties of biomaterials can significantly influence the tissue repair progress through modulating the macrophage functions. In this study, the surface of poly(propylene fumarate) polyurethane films (PPFU) is grafted with a same density of enantiomeric poly-l-lysine (PPFU-g-PLL) and poly-d-lysine (PPFU-g-PDL), leading to a similar level of enhanced surface wettability for the PPFU-g-PLL and PPFU-g-PDL. The polylysine-grafted PPFU can restrict the M1 polarization, whereas promote M2 polarization of macrophages in vitro, judging from the secretion of cytokines and expression of key M1 and M2 related genes. Comparatively, the PPFU-g-PDL has a stronger effect in inducing M2 polarization in vivo, resulting in a thinner fibrous capsule surrounding the implant biomaterials. The CD44 and integrins of macrophages participate in the polarization process probably by activating focal adhesion kinase (FAK) and Rho-associated protein kinase (ROCK), and downstream PI3K/Akt1/mTOR signal axis to up regulate M2 related gene expression. This study confirms for the first time that polylysine coating is an effective method to regulate the immune response of biomaterials, and the polylysine-modified thermoplastic PPFU with the advantage to promote M2 polarization may be applied widely in regenerative medicine.

Long noncoding RNA FOXD2-AS1 enhances chemotherapeutic resistance of laryngeal squamous cell carcinoma via STAT3 activation

Laryngeal squamous cell carcinoma (LSCC) is a common head and neck cancer. Despite recently improved management of LSCC, chemotherapy resistance of patients remains a challenge. In this study, we identified that long noncoding RNA FOXD2-AS1 regulates LSCC therapeutic resistance by augmenting LSCC stemness. LSCC chemotherapy-resistant patients showed increased FOXD2-AS1 expression compared with that in chemotherapy-sensitive patients, which predicted poor prognosis. Gain- or loss-of-function experiments showed that upregulated FOXD2-AS1 maintained cancer stemness, reducing the response to chemotherapy, while FOXD2-AS1 downregulation had the opposite effects. FOXD2-AS1 acted as a scaffold for STAT3 and PRMT5, promoting STAT3 transcriptional activity, which is essential to maintain cancer stemness and promote chemotherapeutic resistance. Interfering with FOXD2-AS1 using short hairpin RNA rescued LSCC’s chemotherapeutic sensitivity. Thus, FOXD2-AS1 promotes LSCC chemotherapeutic resistance and is an upstream activator of STAT3, making FOXD2-AS1 a potential therapeutic target to improve the chemotherapy effect in LSCC patients.

Deriving a Boolean dynamics to reveal macrophage activation with in vitro temporal cytokine expression profiles

BACKGROUND

Macrophages show versatile functions in innate immunity, infectious diseases, and progression of cancers and cardiovascular diseases. These versatile functions of macrophages are conducted by different macrophage phenotypes classified as classically activated macrophages and alternatively activated macrophages due to different stimuli in the complex in vivo cytokine environment. Dissecting the regulation of macrophage activations will have a significant impact on disease progression and therapeutic strategy. Mathematical modeling of macrophage activation can improve the understanding of this biological process through quantitative analysis and provide guidance to facilitate future experimental design. However, few results have been reported for a complete model of macrophage activation patterns.

RESULTS

We globally searched and reviewed literature for macrophage activation from PubMed databases and screened the published experimental results. Temporal in vitro macrophage cytokine expression profiles from published results were selected to establish Boolean network models for macrophage activation patterns in response to three different stimuli. A combination of modeling methods including clustering, binarization, linear programming (LP), Boolean function determination, and semi-tensor product was applied to establish Boolean networks to quantify three macrophage activation patterns. The structure of the networks was confirmed based on protein-protein-interaction databases, pathway databases, and published experimental results. Computational predictions of the network evolution were compared against real experimental results to validate the effectiveness of the Boolean network models.

CONCLUSION

Three macrophage activation core evolution maps were established based on the Boolean networks using Matlab. Cytokine signatures of macrophage activation patterns were identified, providing a possible determination of macrophage activations using extracellular cytokine measurements.

Interferon target-gene expression and epigenomic signatures in health and disease

Multiple type I interferons and interferon-γ (IFN-γ) are expressed under physiological conditions and are increased by stress and infections, and in autoinflammatory and autoimmune diseases. Interferons activate the Jak-STAT signaling pathway and induce overlapping patterns of expression, called 'interferon signatures', of canonical interferon-stimulated genes (ISGs) encoding molecules important for antiviral responses, antigen presentation, autoimmunity and inflammation. It has now become clear that interferons also induce an 'interferon epigenomic signature' by activating latent enhancers and 'bookmarking' chromatin, thus reprogramming cell responses to environmental cues. The interferon epigenomic signature affects ISGs and other gene sets, including canonical targets of the transcription factor NF-κB that encode inflammatory molecules, and is involved in the priming of immune cells, tolerance and the training of innate immune memory. Here we review the mechanisms through which interferon signatures and interferon epigenomic signatures are generated, as well as the expression and functional consequences of these signatures in homeostasis and autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis.

A mechanistic integrative computational model of macrophage polarization: Implications in human pathophysiology

Macrophages respond to signals in the microenvironment by changing their functional phenotypes, a process known as polarization. Depending on the context, they acquire different patterns of transcriptional activation, cytokine expression and cellular metabolism which collectively constitute a continuous spectrum of phenotypes, of which the two extremes are denoted as classical (M1) and alternative (M2) activation. To quantitatively decode the underlying principles governing macrophage phenotypic polarization and thereby harness its therapeutic potential in human diseases, a systems-level approach is needed given the multitude of signaling pathways and intracellular regulation involved. Here we develop the first mechanism-based, multi-pathway computational model that describes the integrated signal transduction and macrophage programming under M1 (IFN-γ), M2 (IL-4) and cell stress (hypoxia) stimulation. Our model was calibrated extensively against experimental data, and we mechanistically elucidated several signature feedbacks behind the M1-M2 antagonism and investigated the dynamical shaping of macrophage phenotypes within the M1-M2 spectrum. Model sensitivity analysis also revealed key molecular nodes and interactions as targets with potential therapeutic values for the pathophysiology of peripheral arterial disease and cancer. Through simulations that dynamically capture the signal integration and phenotypic marker expression in the differential macrophage polarization responses, our model provides an important computational basis toward a more quantitative and network-centric understanding of the complex physiology and versatile functions of macrophages in human diseases.

Peripheral Innate Lymphoid Cells Are Increased in First Line Metastatic Colorectal Carcinoma Patients: A Negative Correlation With Th1 Immune Responses

Several distinct innate lymphoid cell (ILC) populations have been recently identified and shown to play a critical role in the immediate immune defense. In the context of tumors, there is evidence to support a dual role for ILCs with pro- or antitumor effects, depending on the ILC subset and the type of cancer. This ambivalent role has been particularly well-described in colorectal cancer models (CRC), but the presence and the evolution of ILCs in the peripheral blood of metastatic CRC (mCRC) patients have not yet been explored. Here, we investigated the distribution of ILC subsets in 96 mCRC patients who were prospectively included in the “Epitopes-CRC02” trial. Peripheral blood mononuclear cells (PBMCs) were analyzed by flow cytometry at metastatic diagnosis and after 3-months of treatment. The treatments consisted of Oxaliplatin-based chemotherapies for 76% of the patients or Folfiri (5FU, Irinotecan) chemotherapies for 14% of patients. Compared to healthy donors, the frequency of total ILCs was dramatically increased at metastatic diagnosis. CD56⁺ ILC1-like cells were expanded, whereas ILC2, NCR⁻ ILCP and NCR⁺ ILCP subsets were decreased. Combined analysis with the systemic anti-telomerase hTERT Th1 CD4 response revealed that patients with low anti-TERT Th1 CD4 responses had the highest frequencies of total ILCs at diagnosis. Of those, 91% had synchronous metastases, and their median progression-free survival was 7.43 months (vs. 9.17 months for the other patients). In these patients, ILC1 and ILC2 were significantly decreased, whereas CD56⁺ ILC1-like cells were significantly increased compared to patients with low frequency of total ILCs and high anti-TERT responses. After treatment, the NCR⁺ ILCP were further decreased irrespective of the chemotherapy regimen, whereas the balance between ILC1 and CD56⁺ ILC1-like cells was modulated mainly by the Folfiri regimen in favor of ILC1. Altogether our results describe the effects of different chemotherapies on ILCs in mCRC patients. We also establish for the first time a link between frequency of ILCs and anti-tumor CD4 T cell responses in cancer patients. Thus, our study supports an interest in monitoring ILCs during cancer therapy to possibly identify predictive biomarkers in mCRC.

IFNγ: signalling, epigenetics and roles in immunity, metabolism, disease and cancer immunotherapy

IFNγ is a cytokine with important roles in tissue homeostasis, immune and inflammatory responses and tumour immunosurveillance. Signalling by the IFNγ receptor activates the Janus kinase (JAK)-signal transducer and activator of transcription 1 (STAT1) pathway to induce the expression of classical interferon-stimulated genes that have key immune effector functions. This Review focuses on recent advances in our understanding of the transcriptional, chromatin-based and metabolic mechanisms that underlie IFNγ-mediated polarization of macrophages to an 'M1-like' state, which is characterized by increased pro-inflammatory activity and macrophage resistance to tolerogenic and anti-inflammatory factors. In addition, I describe the newly discovered effects of IFNγ on other leukocytes, vascular cells, adipose tissue cells, neurons and tumour cells that have important implications for autoimmunity, metabolic diseases, atherosclerosis, neurological diseases and immune checkpoint blockade cancer therapy.

Cell Type Specific Expression of Toll-Like Receptors in Human Brains and Implications in Alzheimer's Disease

Toll-like receptors mediate important cellular immune responses upon activation via various pathogenic stimuli such as bacterial or viral components. The activation and subsequent secretion of cytokines and proinflammatory factors occurs in the whole body including the brain. The subsequent inflammatory response is crucial for the immune system to clear the pathogen(s) from the body via the innate and adaptive immune response. Within the brain, astrocytes, neurons, microglia, and oligodendrocytes all bear unique compositions of Toll-like receptors. Besides pathogens, cellular damage and abnormally folded protein aggregates, such as tau and Amyloid beta peptides, have been shown to activate Toll-like receptors in neurodegenerative diseases such as Alzheimer's disease. This review provides an overview of the different cell type-specific Toll-like receptors of the human brain, their activation mode, and subsequent cellular response, as well as their activation in Alzheimer's disease. Finally, we critically evaluate the therapeutic potential of targeting Toll-like receptors for treatment of Alzheimer's disease as well as discussing the limitation of mouse models in understanding Toll-like receptor function in general and in Alzheimer's disease.

Fine-Tuning of Type I Interferon Response by STAT3

Type I interferon (IFN-I) is induced during innate immune response and is required for initiating antiviral activity, growth inhibition, and immunomodulation. STAT1, STAT2, and STAT3 are activated in response to IFN-I stimulation. STAT1, STAT2, and IRF9 form ISGF3 complex which transactivates downstream IFN-stimulated genes and mediates antiviral response. However, the role of STAT3 remains to be characterized. Here, we review the multiple actions of STAT3 on suppressing IFN-I responses, including blocking IFN-I signaling, downregulating the expression of ISGF3 components, and antagonizing the transcriptional activity of ISGF3. Finally, we discuss the evolution of the suppressive activity of STAT3 and the therapeutic potential of STAT3 inhibitors in host defense against viral infections and IFN-I-associated diseases.

Signal Integration of IFN-I and IFN-II With TLR4 Involves Sequential Recruitment of STAT1-Complexes and NFκB to Enhance Pro-inflammatory Transcription

Atherosclerosis is a chronic inflammatory disease of the blood vessels, characterized by atherosclerotic lesion formation. Vascular Smooth Muscle Cells (VSMC), macrophages (MΦ), and dendritic cells (DC) play a crucial role in vascular inflammation and atherosclerosis. Interferon (IFN)α, IFNγ, and Toll-like receptor (TLR)4 activate pro-inflammatory gene expression and are pro-atherogenic. Gene expression regulation of many pro-inflammatory genes has shown to rely on Signal Integration (SI) between IFNs and TLR4 through combinatorial actions of the Signal Transducer and Activator of Transcription (STAT)1 complexes ISGF3 and γ-activated factor (GAF), and Nuclear Factor-κB (NFκB). Thus, IFN pre-treatment (“priming”) followed by LPS stimulation leads to enhanced transcriptional responses as compared to the individual stimuli. To characterize the mechanism of priming-induced IFNα + LPS- and IFNγ + LPS-dependent SI in vascular cells as compared to immune cells, we performed a comprehensive genome-wide analysis of mouse VSMC, MΦ, and DC in response to IFNα, IFNγ, and/or LPS. Thus, we identified IFNα + LPS or IFNγ + LPS induced genes commonly expressed in these cell types that bound STAT1 and p65 at comparable γ-activated sequence (GAS), Interferon-stimulated response element (ISRE), or NFκB sites in promoter proximal and distal regions. Comparison of the relatively high number of overlapping ISRE sites in these genes unraveled a novel role of ISGF3 and possibly STAT1/IRF9 in IFNγ responses. In addition, similar STAT1-p65 co-binding modes were detected for IFNα + LPS and IFNγ + LPS up-regulated genes, which involved recruitment of STAT1 complexes preceding p65 to closely located GAS/NFκB or ISRE/NFκB composite sites already upon IFNα or IFNγ treatment. This STAT1-p65 co-binding significantly increased after subsequent LPS exposure and correlated with histone acetylation, PolII recruitment, and amplified target gene transcription in a STAT1-p65 co-bound dependent manner. Thus, co-binding of STAT1-containing transcription factor complexes and NFκB, activated by IFN-I or IFN-II together with LPS, provides a platform for robust transcriptional activation of pro-inflammatory genes. Moreover, our data offer an explanation for the comparable effects of IFNα or IFNγ priming on TLR4-induced activation in vascular and immune cells, with important implications in atherosclerosis.

Postprandial inflammatory responses after oral glucose, lipid and protein challenges: Influence of obesity, sex and polycystic ovary syndrome

BACKGROUND & AIMS

Most evidence linking the polycystic ovary syndrome (PCOS) with chronic low-grade inflammation has been obtained in the fasting state. We have studied the postprandial inflammatory response to oral glucose, lipid and protein challenges and the possible influences of obesity, sex and PCOS on these responses.

METHODS

On alternate days, we submitted 17 women with PCOS (9 non-obese, 8 obese), 17 control women (9 non-obese, 8 obese) and 19 control men (10 non-obese, 9 obese) to isocaloric (300 Kcal) oral macronutrient loads. We assayed serum for TNF-α, IL-6, IL-18, IL-10, pentraxin-3 and galectin-3 concentrations and leukocytes for expression of TNF, IL6, IL10 and their receptors TNFRSF1B, IL6R and IL10RA.

RESULTS

Circulating IL-6 levels decreased after glucose and protein ingestion but slightly increased after oral lipid intake. Leukocyte IL6 expression did not change after the ingestion of any macronutrient yet IL6R expression increased during all macronutrient challenges, the largest increase being observed after glucose ingestion. Serum TNF-α similarly decreased during either macronutrient load, whereas TNF expression increased after macronutrient ingestion, the highest increase observed after oral glucose. TNFRSF1B expression also increased after glucose intake but not after lipid or protein ingestion. No global effect of obesity or group on postprandial circulating IL-6, TNF-α, or IL6, IL6R, TNF and TNFRSF1B expression was found. Circulating IL-18 concentrations decreased during all oral challenges, whereas in case of galectin-3 and pentraxin-3 only the protein load caused a reduction in its concentrations. Of the genes studied here, IL10 showed the largest increase in expression throughout all the postprandial curves, particularly after glucose. Obesity blunted the increase in IL10 expression. IL10RA expression decreased after glucose ingestion but remained unchanged during lipid and protein loads.

CONCLUSIONS

Glucose ingestion, as opposed to lipid and protein intake, results into the largest increase in leukocyte gene expression of inflammatory mediators. The expression of the anti-inflammatory cytokine IL10 was the largest observed here, suggesting a compensatory mechanisms against postprandial inflammation that may be blunted in obesity. However, these responses did not translate into the circulating concentrations of these inflammatory mediators during the immediate postprandial phase.

Interferon (IFN)-inducible Absent in Melanoma 2 proteins in the negative regulation of the type I IFN response: Implications for lupus nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease that exhibits a strong female bias (female-to-male ratio 9:1) in patients. Further, 40-60% SLE patients develop lupus nephritis (LN), which significantly increases the mortality rates. The failure of current therapies to adequately treat LN in patients reflects an incomplete understanding of the disease pathogenesis. Notably, a chronic increase in serum interferon-α (IFN-α) activity is a heritable risk factor to develop SLE. Accordingly, blood cells from most SLE patients with an active disease exhibit an increase in the expression of the type I IFN (IFN-α/β)-stimulated genes (ISGs, also referred to as "IFN-signature"), a type I IFN response. Further, LN patients during renal flares also exhibit an "IFN-signature" in renal biopsies. Therefore, an improved understanding of the regulation of type I IFNs expression is needed. Basal levels of the IFN-β through "priming" of IFN-α producing cells augment the expression of the IFN-α genes. Of interest, recent studies have indicated a role for the type I IFN-inducible Absent in Melanoma 2 proteins (the murine Aim2 and human AIM2) in the negative regulation of the type I IFN response through inflammasome-dependent and independent mechanisms. Further, an increase in the expression of Aim2 and AIM2 proteins in kidney and renal macrophages associated with the development of nephritis. Therefore, we discuss the role of Aim2/AIM2 proteins in the regulation of type I IFNs and LN. An improved understanding of the mechanisms by which the Absent in Melanoma 2 proteins suppress the type I IFN response and modulate nephritis is key to identify novel therapeutic targets to treat a group of LN patients.

A non-linear mixed effect model for innate immune response: In vivo kinetics of endotoxin and its induction of the cytokines tumor necrosis factor alpha and interleukin-6

Endotoxin, a component of the outer membrane of Gram-negative bacteria, has been extensively studied as a stimulator of the innate immune response. However, the temporal aspects and exposure-response relationship of endotoxin and resulting cytokine induction and tolerance development is less well defined. The aim of this work was to establish an in silico model that simultaneously captures and connects the in vivo time-courses of endotoxin, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and associated tolerance development. Data from six studies of porcine endotoxemia in anesthetized piglets (n = 116) were combined and used in the analysis, with purified endotoxin (Escherichia coli O111:B4) being infused intravenously for 1–30 h in rates of 0.063–16.0 μg/kg/h across studies. All data were modelled simultaneously by means of importance sampling in the non-linear mixed effects modelling software NONMEM. The infused endotoxin followed one-compartment disposition and non-linear elimination, and stimulated the production of TNF-α to describe the rapid increase in plasma concentration. Tolerance development, observed as declining TNF-α concentration with continued infusion of endotoxin, was also driven by endotoxin as a concentration-dependent increase in the potency parameter related to TNF-α production (EC₅₀). Production of IL-6 was stimulated by both endotoxin and TNF-α, and four consecutive transit compartments described delayed increase in plasma IL-6. A model which simultaneously account for the time-courses of endotoxin and two immune response markers, the cytokines TNF-α and IL-6, as well as the development of endotoxin tolerance, was successfully established. This model-based approach is unique in its description of the time-courses and their interrelation and may be applied within research on immune response to bacterial endotoxin, or in pre-clinical pharmaceutical research when dealing with study design or translational aspects.

Brief Report: Interferon-γ-Mediated Immunopathology Potentiated by Toll-Like Receptor 9 Activation in a Murine Model of Macrophage Activation Syndrome

OBJECTIVE

Macrophage activation syndrome (MAS) is a life-threatening cytokine storm syndrome that occurs in patients with underlying rheumatic diseases. Preclinical and clinical data suggest that interferon-γ (IFNγ) is pathogenic in MAS, but how IFNγ may be linked to disease pathogenesis remains unknown. This study was undertaken to determine whether IFNγ signals synergize with systemic innate immune responses to drive the cytokine storm in a murine model of MAS.

METHODS

IFNγ-deficient mice were treated with 5 doses of the Toll-like receptor 9 (TLR-9) agonist CpG 1826, IFNγ, or a combination of the 2 stimuli over the course of 10 days. Immunopathologic features of MAS, including cytopenias, hepatitis, hepatosplenomegaly, and induction of inflammatory myelopoiesis, were assessed. Mixed bone marrow chimeras were created to determine whether TLR-9- and IFNγ receptor 1 (IFNγR1)-dependent signals induce enhanced myelopoiesis in a cell-intrinsic or cell-extrinsic manner.

RESULTS

IFNγ-deficient mice did not develop features of MAS when treated with repeated doses of either the TLR-9 agonist or IFNγ alone. In contrast, IFNγ-deficient mice treated with both the TLR-9 agonist and IFNγ developed cytopenias, hepatitis, and hepatosplenomegaly, reproducing major clinical features of MAS. TLR-9- and IFNγR1-dependent signals synergized to enhance myeloid progenitor cell function and induce myelopoiesis in vivo, which occurred through cell-extrinsic mechanisms and correlated with the induction of disease.

CONCLUSION

These findings demonstrate that TLR-9-driven signals potentiate the effects of IFNγ to initiate murine MAS, and provide evidence that induction of inflammatory myelopoiesis is a common TLR-9- and IFNγ-dependent pathway that may contribute to the pathogenesis of MAS.

Comprehensive network map of interferon gamma signaling

Interferon gamma (IFN-γ), is a cytokine, which is an important regulator of host defense system by mediating both innate and adaptive immune responses. IFN-γ signaling is primarily associated with inflammation and cell-mediated immune responses. IFN-γ is also represented as antitumor cytokine which facilitates immunosurveillance in tumor cells. In addition, IFN-γ mediated signaling also elicits pro-tumorigenic transformations and promotes tumor progression. Impact of IFN-γ signaling in mammalian cells has been widely studied which indicate that IFN-γ orchestrates distinct cellular functions including immunomodulation, leukocyte trafficking, apoptosis, anti-microbial, and both anti- and pro-tumorigenic role. However, a detailed network of IFN-γ signaling pathway is currently lacking. Therefore, we systematically curated the literature information pertaining to IFN-γ signaling and develop a comprehensive signaling network to facilitate better understanding of IFN-γ mediated signaling. A total of 124 proteins were catalogued that were experimentally proven to be involved in IFN-γ signaling cascade. These 124 proteins were found to participate in 81 protein-protein interactions, 94 post-translational modifications, 20 translocation events, 54 activation/inhibiton reactions. Further, 236 differential expressed genes were also documented in IFN-γ mediated signaling. IFN-γ signaling pathway is made freely available to scientific audience through NetPath at ( http://www.netpath.org/pathways?path_id=NetPath_32 ). We believe that documentation of reactions pertaining to IFN-γ signaling and development of pathway map will facilitate further research in IFN-γ associated human diseases including cancer.

Influence of Immunological Maturity on Respiratory Syncytial Virus-Induced Morbidity in Young Children

Respiratory syncytial virus (RSV) is a very frequent viral respiratory pathogen of the young (<5 years old) with a significant portion of young toddlers having been infected before 2 years of age. Although we understand that some of the morbidity associated with RSV in neonates is due to immunological maturation that favors immunosuppression over antiviral innate and/or adaptive immune responses, the rapid development of the immune system right after birth suggests that each age group (newborn, early infant, older infant, toddler, and older) may respond to the virus in different ways. In this study, we summarize the morbidity associated with infection in young children in the context of immunological maturation of monocytes/macrophages and the ramifications for poor innate control of viral pathogenesis. We also summarize key mechanisms that contribute to the diminished antiviral innate immune responses of these young children.

Viral Encephalitis and Neurologic Diseases: Focus on Astrocytes

Neurotropic RNA virus infections cause a major neurological disease burden. Due to the morbidity and mortality rates of viral encephalitides worldwide, there is a need to develop clinical treatments. Features of the central nervous system (CNS), including interconnected cell types and limited regeneration, provide unique challenges. Viral encephalitis and antiviral immunity can disrupt the CNS environment, leaving patients with poor neurological outcomes despite virologic control. The cellular mechanism(s) underlying neurological recovery are not fully understood, but involve neuroimmune interactions that, until recently, primarily focused on microglia. With increasing evidence that astrocytes also have significant roles in inflammatory responses to viruses, here we summarize recent astrocyte contributions to acute virologic control and neurological impairments during recovery from viral infection.

Psychoneuroimmunology and immunopsychiatry of zebrafish

Despite the high prevalence of neural and immune disorders, their etiology and molecular mechanisms remain poorly understood. As the zebrafish (Danio rerio) is increasingly utilized as a powerful model organism in biomedical research, mounting evidence suggests these fish as a useful tool to study neural and immune mechanisms and their interplay. Here, we discuss zebrafish neuro-immune mechanisms and their pharmacological and genetic modulation, the effect of stress on cytokines, as well as relevant models of microbiota-brain interplay. As many human brain diseases are based on complex interplay between the neural and the immune system, here we discuss zebrafish models, as well as recent successes and challenges, in this rapidly expanding field. We particularly emphasize the growing utility of zebrafish models in translational immunopsychiatry research, as they improve our understanding of pathogenetic neuro-immune interactions, thereby fostering future discovery of potential therapeutic agents.

Transcriptional Regulation of Macrophages Polarization by MicroRNAs

Diversity and plasticity are the hallmarks of cells from the monocyte-macrophage lineage. Macrophages undergo classical M1 or alternative M2 activation in response to the microenvironment signals. Several transcription factors, such as peroxisome proliferator-activated receptors, signal transducers and activators of transcription, CCAAT-enhancer-binding proteins, interferon regulatory factors, Kruppel-like factors, GATA binding protein 3, nuclear transcription factor-κB, and c-MYC, were found to promote the expression of specific genes, which dictate the functional polarization of macrophages. Importantly, these transcription factors can be regulated by microRNAs (miRNAs), a group of small non-coding RNAs, which regulate gene expression through translation repression or mRNA degradation. Recent studies have also revealed that miRNAs control macrophage polarization by regulating transcription factors in response to the microenvironment signals. This review will summarize recent progress of miRNAs in the transcriptional regulation of macrophage polarization and provide the insights into the development of macrophage-centered diagnostic and therapeutic strategies.

A model for the integration of conflicting exogenous and endogenous signals by dendritic cells

Cells of the immune system are confronted with opposing pro- and anti-inflammatory signals. Dendritic cells (DC) integrate these cues to make informed decisions whether to initiate an immune response. Confronted with exogenous microbial stimuli, DC endogenously produce both anti- (IL-10) and pro-inflammatory (TNFα) cues whose joint integration controls the cell's final decision. Backed by experimental measurements we present a theoretical model to quantitatively describe the integration mode of these opposing signals. We propose a two step integration model that modulates the effect of the two types of signals: an initial bottleneck integrates both signals (IL-10 and TNFα), the output of which is later modulated by the anti-inflammatory signal. We show that the anti-inflammatory IL-10 signaling is long ranged, as opposed to the short-ranged pro-inflammatory TNFα signaling. The model suggests that the population averaging and modulation of the pro-inflammatory response by the anti-inflammatory signal is a safety guard against excessive immune responses.

Modulation of Innate Immune-Related Genes and Glucocorticoid Synthesis in Gnotobiotic Full-Sibling European Sea Bass (Dicentrarchus labrax) Larvae Challenged With Vibrio anguillarum

Although several efforts have been made to describe the immunoendocrine interaction in fish, there are no studies to date focusing on the characterization of the immune response and glucocorticoid synthesis using the host-pathogen interaction on larval stage as an early developmental stage model of study. Therefore, the aim of this study was to evaluate the glucocorticoid synthesis and the modulation of stress- and innate immune-related genes in European sea bass (Dicentrarchus labrax) larvae challenged with Vibrio anguillarum. For this purpose, we challenged by bath full-sibling gnotobiotic sea bass larvae with 10⁷ CFU mL^-1 of V. anguillarum strain HI 610 on day 5 post-hatching (dph). The mortality was monitored up to the end of the experiment [120 hours post-challenge (hpc)]. While no variations were registered in non-challenged larvae maintained under gnotobiotic conditions (93.20% survival at 120 hpc), in the challenged group a constant and sustained mortality was observed from 36 hpc onward, dropping to 18.31% survival at 120 hpc. Glucocorticoid quantification and expression analysis of stress- and innate immunity-related genes were carried out in single larvae. The increase of cortisol, cortisone and 20β-dihydrocortisone was observed at 120 hpc, although did not influence upon the modulation of stress-related genes (glucocorticoid receptor 1 [gr1], gr2, and heat shock protein 70 [hsp70]). On the other hand, the expression of lysozyme, transferrin, and il-10 differentially increased at 120 hpc together with a marked upregulation of the pro-inflammatory cytokines (il-1β and il-8) and hepcidin, suggesting a late activation of defense mechanisms against V. anguillarum. Importantly, this response coincided with the lowest survival observed in challenged groups. Therefore, the increase in markers associated with glucocorticoid synthesis together with the upregulation of genes associated with the anti-inflammatory response suggests that in larvae infected with V. anguillarum a pro-inflammatory response at systemic level takes place, which then leads to the participation of other physiological mechanisms at systemic level to counteract the effect and the consequences of such response. However, this late systemic response could be related to the previous high mortality observed in sea bass larvae challenged with V. anguillarum.

The efficiency of lipid nanoparticles with an original cationic lipid as a siRNA delivery system for macrophages and dendritic cells

Small interfering of RNA (siRNA) technology has the potential to be a next-generation therapy. However, naked siRNA does not have high transfection efficiency and is rapidly degraded after systemic injection, so an appropriate drug delivery system (DDS) is required for clinical use. Several potential systems have been assessed, clinically focusing on hepatocyte or cancer tissue using siRNA. However, targeting immune cells using siRNA is still challenging, and a new DDS is required. In this study, we prepared lipid nanoparticles (LNP) composed of original cationic lipid, neutral lipid of DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and PEG2000-DMPE (N-(carbonyl-methoxypolyethyleneglycol 2000)-1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine, sodium salt). Our LNP encapsulating siRNA (LNP/siRNA) exerted a knock-down (KD) effect on mouse inflammatory peritoneal macrophages in vitro. In addition, an in vivo KD effect by systemic administration of LNP/siRNA was observed in macrophages and dendritic cells (DCs) in mice. Furthermore, our LNP/siRNA showed in vitro KD effects not only on murine cells but also on human cells like monocyte-derived macrophages (MDMs) and monocyte-derived DCs (MDDCs). These results indicate the potential utility of our LNP for siRNA-based therapy targeting macrophages and DCs. Because these cells are known to have a significant role in several kinds of diseases, and siRNA can specifically suppress target genes that are closely associated with disease states and are untreatable by small molecules or antibodies. Therefore, delivering siRNA by our LNP to macrophages and DCs could provide novel therapies.

Conventional and novel "omics"-based approaches to the study of carbon nanotubes pulmonary toxicity

The widespread application of carbon nanotubes (CNT) on industrial, biomedical, and consumer products can represent an emerging respiratory occupational hazard. Particularly, their similarity with the fiber-like shape of asbestos have raised a strong concern about their carcinogenic potential. Several in vitro and in vivo studies have been supporting this view by pointing to immunotoxic, cytotoxic and genotoxic effects of some CNT that may conduct to pulmonary inflammation, fibrosis, and bronchioloalveolar hyperplasia in rodents. Recently, high throughput molecular methodologies have been applied to obtain more insightful information on CNT toxicity, through the identification of the affected biological and molecular pathways. Toxicogenomic approaches are expected to identify unique gene expression profiles that, besides providing mechanistic information and guiding new research, have also the potential to be used as biomarkers for biomonitoring purposes. In this review, the potential of genomic data analysis is illustrated by gene network and gene ontology enrichment analysis of a set of 41 differentially expressed genes selected from a literature search focused on studies of C57BL/6 mice exposed to the multiwalled CNT Mitsui-7. The majority of the biological processes annotated in the network are regulatory processes and the molecular functions are related to receptor-binding signalling. Accordingly, the network-annotated pathways are cell receptor-induced pathways. A single enriched molecular function and one biological process were identified. The relevance of specific epigenomic effects triggered by CNT exposure, for example, alteration of the miRNA expression profile is also discussed in light of its use as biomarkers in occupational health studies. Environ. Mol. Mutagen. 59:334-362, 2018. © 2018 Wiley Periodicals, Inc.

Zymosan attenuates melanoma growth progression, increases splenocyte proliferation and induces TLR-2/4 and TNF-α expression in mice

Background

Melanoma is one of the most common types of skin malignancies. Since current therapies are suboptimal, considerable interest has focused on novel natural-based treatments. Toll-like receptors (TLRs) play an important role in evoking innate immunity against cancer cells. Zymosan, a known TLR-2 agonist, is a glucan derived from yeast cell walls with promising immunomodulatory effects. The aim of this study was to evaluate whether Saccharomyces cerevisiae-derived zymosan-modulated skin melanoma progression by regulation of TLR-2 and TLR-4 expression in peritoneal macrophages and serum TNF-α level.

Methods

Male C57BL/6 mice were divided into four groups: i) zymosan-treated (Z), ii) Melanoma-bearing mice (M), iii) Melanoma-bearing mice treated with zymosan (ZM) and iv) a healthy control group (negative control). 15 days after melanoma induction, mice were injected i.p. with zymosan (10 μg) daily for 4 consecutive days. Mice were CO₂-euthanized and serum TNF-α level, TLR-2 and TLR-4 expression in peritoneal macrophages and tumor growth measured. Splenocytes were treated ex-vivo with zymosan to determine viability and proliferation.

Results

Tumor weight significantly decreased following therapeutic dosing with zymosan (P < 0.05). This was associated with zymosan-induced upregulation of TLR-2, TLR-4 and TNF-α mRNA in peritoneal macrophages and enhanced serum TNF-α levels (P < 0.05). Splenocyte number and viability were increased in a concentration-dependent manner by zymosan.

Conclusions

Our study suggests that zymosan-induced upregulation of TLR-2, TLR-4 and TNF-α gene expression and of TNF-α release; together with increased level of lymphocyte proliferation may play a role in the inhibition of melanoma progression.

Partners in crime: neutrophils and monocytes/macrophages in inflammation and disease

Neutrophils are becoming recognized as highly versatile and sophisticated cells that display de novo synthetic capacity and potentially prolonged lifespan. Emerging concepts such as neutrophil heterogeneity and plasticity have revealed that, under pathological conditions, neutrophils may differentiate into discrete subsets defined by distinct phenotypic and functional characteristics. Indeed, these newly described neutrophil subsets will undoubtedly add to the already complex interactions between neutrophils and other immune cell types for an effective immune response. The interactions between neutrophils and monocytes/macrophages enable the host to efficiently defend against and eliminate foreign pathogens. However, it is also becoming increasingly clear that these interactions can be detrimental to the host if not tightly regulated. In this review, we will explore the functional cooperation of neutrophil and monocytes/macrophages in homeostasis, during acute inflammation and in various disease settings. We will discuss this in the context of cardiovascular disease in the form of atherosclerosis, an autoimmune disease mainly occurring in the kidneys, as well as the unique intestinal immune response of the gut that does not conform to the norms of the typical immune system.

The effects of glucose concentrations associated with lipopolysaccharide and interferon-gamma stimulus on mediators' production of RAW 264.7 cells

Diabetes mellitus (DM) is a metabolic disorder that results in the impairment of the metabolism of carbohydrates, proteins and lipids. It can give rise to various complications, mainly caused by chronic exposure of cells to high glucose concentrations, including changes in the immune response processes. The aim of this study was to verify the chemokine and cytokines production profile in the presence of different glucose concentrations and infection/inflammatory stimuli. To this end, cell viability and the production of chemokines, cytokines and nitric oxide (NO) were analyzed in RAW 264.7 cell culture. Results demonstrated that there was no change in cell viability after 6, 24 and 72 h. Different stimuli were unable to modify the monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-α production. Groups stimulated with lipopolysaccharides (LPS) and LPS and recombinant interferon (rIFN)-γ down-regulated interleukin (IL)-1α, IL-10 and IL-12 and up-regulated IL-6 production. NO production maintained a pattern of increase, according to the increase in glucose concentrations, reaching its peak at 72 h. In summary, the results demonstrated that high glucose concentrations alone may be sufficient to alter the in vitro mediators' production of RAW 264.7 cells.

Targeted inhibition of STATs and IRFs as a potential treatment strategy in cardiovascular disease

Key factors contributing to early stages of atherosclerosis and plaque development include the pro-inflammatory cytokines Interferon (IFN)α, IFNγ and Interleukin (IL)-6 and Toll-like receptor 4 (TLR4) stimuli. Together, they trigger activation of Signal Transducer and Activator of Transcription (STAT) and Interferon Regulatory Factor (IRF) families. In particular, STAT1, 2 and 3; IRF1 and 8 have recently been recognized as prominent modulators of inflammation, especially in immune and vascular cells during atherosclerosis. Moreover, inflammation-mediated activation of these STATs and IRFs coordinates a platform for synergistic amplification leading to pro-atherogenic responses.

Searches for STAT3-targeting compounds, exploring the pTyr-SH2 interaction area of STAT3, yielded many small molecules including natural products. Only a few inhibitors for other STATs, but none for IRFs, are described. Promising results for several STAT3 inhibitors in recent clinical trials predicts STAT3-inhibiting strategies may find their way to the clinic. However, many of these inhibitors do not seem STAT-specific, display toxicity and are not very potent. This illustrates the need for better models, and screening and validation tools for novel STAT and IRF inhibitors.

This review presents a summary of these findings. It postulates STAT1, STAT2 and STAT3 and IRF1 and IRF8 as interesting therapeutic targets and targeted inhibition could be a potential treatment strategy in CVDs. In addition, it proposes a pipeline approach that combines comparative in silico docking of STAT-SH2 and IRF-DBD models with in vitro STAT and IRF activation inhibition validation, as a novel tool to screen multi-million compound libraries and identify specific inhibitors for STATs and IRFs.

Module Analysis Captures Pancancer Genetically and Epigenetically Deregulated Cancer Driver Genes for Smoking and Antiviral Response

The availability of increasing volumes of multi-omics profiles across many cancers promises to improve our understanding of the regulatory mechanisms underlying cancer. The main challenge is to integrate these multiple levels of omics profiles and especially to analyze them across many cancers. Here we present AMARETTO, an algorithm that addresses both challenges in three steps. First, AMARETTO identifies potential cancer driver genes through integration of copy number, DNA methylation and gene expression data. Then AMARETTO connects these driver genes with co-expressed target genes that they control, defined as regulatory modules. Thirdly, we connect AMARETTO modules identified from different cancer sites into a pancancer network to identify cancer driver genes. Here we applied AMARETTO in a pancancer study comprising eleven cancer sites and confirmed that AMARETTO captures hallmarks of cancer. We also demonstrated that AMARETTO enables the identification of novel pancancer driver genes. In particular, our analysis led to the identification of pancancer driver genes of smoking-induced cancers and 'antiviral' interferon-modulated innate immune response.

SOFTWARE AVAILABILITY

AMARETTO is available as an R package at https://bitbucket.org/gevaertlab/pancanceramaretto.

Zinc chelation decreases IFN-β-induced STAT1 upregulation and iNOS expression in RAW 264.7 macrophages

One consequence of lipopolysaccharide (LPS)-induced stimulation of macrophages is the release of Interferon (IFN)-β, and subsequently the activation of the JAK-STAT1 pathway, resulting in the expression of inducible nitric oxide synthase (iNOS). Free intracellular zinc ions (Zn²⁺) have a profound impact as a second messenger in LPS-dependent gene expression. Previous work had indicated a Zn²⁺-dependent upregulation of STAT1 mRNA in response to LPS and IFN-β, potentially affecting STAT1-dependent downstream signaling upon pre-incubation with these agents. The aim of the present study was to investigate the long-term influence of Zn²⁺ chelation on cellular STAT1 levels and their effect on protein levels and activity of iNOS. The LPS- and IFN-β-mediated increase of STAT1 mRNA and protein levels was abrogated by chelation of Zn²⁺ with the membrane permeable chelator N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) in RAW 264.7 macrophages. After 48h pre-incubation together with IFN-β, TPEN also led to reduced nitric monoxide formation in response to a second stimulation with LPS. Nonetheless, the latter was observed regardless of any pre-incubation with IFN-β, suggesting that the effect of treatment with TPEN negatively affects iNOS induction independently from cellular STAT1 levels. In conclusion, long term Zn²⁺ chelation does affect STAT1 protein expression, but interferes with NO production by a different, yet unknown pathway not involving STAT1. However, as there are many additional STAT1-dependent genes, there might still be effects on targets other than iNOS.

Defining Genome-Wide Expression and Phenotypic Contextual Cues in Macrophages Generated by Granulocyte/Macrophage Colony-Stimulating Factor, Macrophage Colony-Stimulating Factor, and Heat-Killed Mycobacteria

Heat-killed (HK) Mycobacterium obuense (NCTC13365) is currently being evaluated in the clinic as an immunotherapeutic agent for cancer treatment. Yet, the molecular underpinnings underlying immunomodulatory properties of HK M. obuense are still largely undefined. To fill this void, we sought to perform immunophenotyping, chemokine/cytokine release analysis and genome-wide characterization of monocyte-derived macrophages (MDM) in which monocytes were originally isolated from healthy donors and differentiated by HK M. obuense (Mob-MDM) relative to macrophage colony-stimulating factor (M-MDM) and granulocyte/macrophage colony-stimulating factor (GM-MDM). Immunophenotyping and cytokine release analysis revealed downregulated surface expression of CD36, decreased spontaneous release of CCL2 and increased spontaneous secretion of CCL5, CXCL8/IL-8, IL-6, and TNF-α in Mob-MDM relative to M-MDM and GM-MDM. Analysis of cytostatic activity showed that Mob-MDM exhibited similar growth inhibitory effects on immortalized and malignant epithelial cells compared with GM-MDM but at an elevated rate relative to M-MDM. To understand global cues in Mob-MDM, we performed comparative RNA-sequencing (RNA-Seq) analysis of Mob-MDM relative to GM-MDM and M-MDM (n = 4 donors). Clustering analysis underscored expression profiles (n = 256) that were significantly modulated in Mob-MDM versus both M-MDM and GM-MDM including, among others, chemokines/cytokines and their receptors, enzymes and transcriptions factors. Topological functional analysis of these profiles identified pathways and gene sets linked to Mob-MDM phenotype including nitric oxide production, acute phase response signaling and microbe recognition pathways as well as signaling cues mediated by the proinflammatory cytokine, interferon-gamma, and the intracellular pattern recognition receptor, nucleotide-binding oligomerization domain-containing protein 2. Taken together, our study highlights molecular immune phenotypes and global signaling cues in Mob-MDM that may underlie immunomodulatory properties of HK M. obuense. Such properties could be of valuable use in immunotherapy approaches such as adoptive cell therapy against cancer.

Interferon-γ Represses M2 Gene Expression in Human Macrophages by Disassembling Enhancers Bound by the Transcription Factor MAF

Mechanisms by which interferon (IFN)-γ activates genes to promote macrophage activation are well studied, but little is known about mechanisms and functions of IFN-γ-mediated gene repression. We used an integrated transcriptomic and epigenomic approach to analyze chromatin accessibility, histone modifications, transcription-factor binding, and gene expression in IFN-γ-primed human macrophages. IFN-γ suppressed basal expression of genes corresponding to an "M2"-like homeostatic and reparative phenotype. IFN-γ repressed genes by suppressing the function of enhancers enriched for binding by transcription factor MAF. Mechanistically, IFN-γ disassembled a subset of enhancers by inducing coordinate suppression of binding by MAF, lineage-determining transcription factors, and chromatin accessibility. Genes associated with MAF-binding enhancers were suppressed in macrophages isolated from rheumatoid-arthritis patients, revealing a disease-associated signature of IFN-γ-mediated repression. These results identify enhancer inactivation and disassembly as a mechanism of IFN-γ-mediated gene repression and reveal that MAF regulates the macrophage enhancer landscape and is suppressed by IFN-γ to augment macrophage activation.

Cytokine modulation by stress hormones and antagonist specific hormonal inhibition in rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata) head kidney primary cell culture

A tight interaction between endocrine and immune systems takes place mainly due to the key role of head kidney in both hormone and cytokine secretion, particularly under stress situations in which the physiological response promotes the synthesis and release of stress hormones which may lead into immunomodulation as side effect. Although such interaction has been previously investigated, this study evaluated for the first time the effect of stress-associated hormones together with their receptor antagonists on the expression of cytokine genes in head kidney primary cell culture (HKPCC) of the freshwater rainbow trout (Oncorhynchus mykiss) and the seawater gilthead sea bream (Sparus aurata). The results showed a striking difference when comparing the response obtained in trout and seabream. Cortisol and adrenocorticotropic hormone (ACTH) decreased the expression of immune-related genes in sea bream but not in rainbow trout and this cortisol effect was reverted by the antagonist mifepristone but not spironolactone. On the other hand, while adrenaline reduced the expression of pro-inflammatory cytokines (IL-1β, IL-6) in rainbow trout, the opposite effect was observed in sea bream showing an increased expression (IL-1β, IL-6). Interestingly, this effect was reverted by antagonist propranolol but not phentolamine. Overall, our results confirm the regional interaction between endocrine and cytokine messengers and a clear difference in the sensitivity to the hormonal stimuli between the two species.

RNA sequencing demonstrates large-scale temporal dysregulation of gene expression in stimulated macrophages derived from MHC-defined chicken haplotypes

Discovering genetic biomarkers associated with disease resistance and enhanced immunity is critical to developing advanced strategies for controlling viral and bacterial infections in different species. Macrophages, important cells of innate immunity, are directly involved in cellular interactions with pathogens, the release of cytokines activating other immune cells and antigen presentation to cells of the adaptive immune response. IFNγ is a potent activator of macrophages and increased production has been associated with disease resistance in several species. This study characterizes the molecular basis for dramatically different nitric oxide production and immune function between the B2 and the B19 haplotype chicken macrophages.A large-scale RNA sequencing approach was employed to sequence the RNA of purified macrophages from each haplotype group (B2 vs. B19) during differentiation and after stimulation. Our results demonstrate that a large number of genes exhibit divergent expression between B2 and B19 haplotype cells both prior and after stimulation. These differences in gene expression appear to be regulated by complex epigenetic mechanisms that need further investigation.

Single-cell profiling of dynamic cytokine secretion and the phenotype of immune cells

Natural killer (NK) cells are a highly heterogeneous population of innate lymphocytes that constitute our first line of defense against several types of tumors and microbial infections. Understanding the heterogeneity of these lymphocytes requires the ability to integrate their underlying phenotype with dynamic functional behaviors. We have developed and validated a single-cell methodology that integrates cellular phenotyping and dynamic cytokine secretion based on nanowell arrays and bead-based molecular biosensors. We demonstrate the robust passivation of the polydimethylsiloxane (PDMS)-based nanowells arrays with polyethylene glycol (PEG) and validated our assay by comparison to enzyme-linked immunospot (ELISPOT) assays. We used numerical simulations to optimize the molecular density of antibodies on the surface of the beads as a function of the capture efficiency of cytokines within an open-well system. Analysis of hundreds of individual human peripheral blood NK cells profiled ex vivo revealed that CD56^dimCD16⁺ NK cells are immediate secretors of interferon gamma (IFN-γ) upon activation by phorbol 12-myristate 13-acetate (PMA) and ionomycin (< 3 h), and that there was no evidence of cooperation between NK cells leading to either synergistic activation or faster IFN-γ secretion. Furthermore, we observed that both the amount and rate of IFN-γ secretion from individual NK cells were donor-dependent. Collectively, these results establish our methodology as an investigational tool for combining phenotyping and real-time protein secretion of individual cells in a high-throughput manner.

Guar gum fiber increases suppressor of cytokine signaling-1 expression via toll-like receptor 2 and dectin-1 pathways, regulating inflammatory response in small intestinal epithelial cells

SCOPE

Direct regulation of intestinal inflammation by intact dietary fibers is still unclear. Here, the anti-inflammatory regulation by intact guar gum (GG) was investigated using mice and human intestinal Caco-2 cells.

METHODS AND RESULTS

Administration of dextran sodium sulfate (DSS) increased myeloperoxidase activity and CXC motif chemokine ligand2 (an IL-8 homolog) expression in the small intestines of mice, while supplemental GG reduced these increases. Stimulation of Caco-2 cells with tumor necrosis factor (TNF)-α induced IL-8 expression through nuclear factor kappa B p65, spleen tyrosine kinase, and mitogen-activated protein kinases pathways. Pre-treatment of cells with GG reduced the TNF-α-induced IL-8 expression and cellular signaling. GG increased the suppressor of cytokine signaling (SOCS)-1 expression in Caco-2 cells, suggesting that this is one of the probable mechanisms involved in GG-mediated anti-inflammatory regulation. The anti-inflammatory regulation and SOCS-1 expression induced by GG were sensitive to neutralization of toll-like receptor (TLR)2 and dectin-1, and to inhibition of Janus kinase (JAK) and tyrosine kinase cSrc pathways. Finally, supplemental GG increased SOCS-1 expression in the small intestines of both DSS-administered and normal mice.

CONCLUSION

Intact GG activates TLR2 and dectin-1, and increases SOCS-1 expression via JAK and cSrc pathways, resulting in anti-inflammatory regulation in intestinal epithelium.