Treatment of monocytes with interleukin (IL)-12 plus IL-18 stimulates survival, differentiation and the production of CXC chemokine ligands (CXCL)8, CXCL9 and CXCL10

An immune-competent human gut microphysiological system enables inflammation-modulation by Faecalibacterium prausnitzii

Crosstalk of microbes with human gut epithelia and immune cells is crucial for gut health. However, there is no existing system for a long-term co-culture of human innate immune cells with epithelium and oxygen-intolerant commensal microbes, hindering the understanding of microbe-immune interactions in a controlled manner. Here, we established a gut epithelium-microbe-immune (GuMI) microphysiological system to maintain the long-term continuous co-culture of Faecalibacterium prausnitzii/Faecalibacterium duncaniae with colonic epithelium, antigen-presenting cells (APCs, herein dendritic cells and macrophages), and CD4+ naive T cells circulating underneath the colonic epithelium. In GuMI-APC condition, multiplex cytokine assays suggested that APCs contribute to the elevated level of cytokines and chemokines secreted into both apical and basolateral compartments compared to GuMI condition that lacks APC. In GuMI-APC with F. prausnitzii (GuMI-APC-FP), F. prausnitzii increased the transcription of pro-inflammatory genes such as toll-like receptor 1 (TLR1) and interferon alpha 1 (IFNA1) in the colonic epithelium, without a significant effect on cytokine secretion, compared to the GuMI-APC without bacteria (GuMI-APC-NB). In contrast, in the presence of CD4+ naive T cells (GuMI-APCT-FP), TLR1, IFNA1, and IDO1 transcription levels decreased with a simultaneous increase in F. prausnitzii-induced secretion of pro-inflammatory cytokines (e.g., IL8) compared to GuMI-APC-FP that lacks T cells. These results highlight the contribution of individual innate immune cells in regulating the immune response triggered by the gut commensal F. prausnitzii. The integration of defined populations of immune cells in the gut microphysiological system demonstrated the usefulness of GuMI physiomimetic platform to study microbe-epithelial-immune interactions in healthy and disease conditions.

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

Extracellular vesicles of Trypanosoma cruzi and immune complexes they form with sialylated and non-sialylated IgGs increase small peritoneal macrophage subpopulation and elicit different cytokines profiles

American trypanosomiasis, or Chagas disease, is caused by the protozoan parasite Trypanosoma cruzi and is characterized by the presence of cardiac or gastrointestinal symptoms in a large number of patients during the chronic phase of the disease. Although the origin of the symptoms is not clear, several mechanisms have been described involving factors related to T. cruzi and the host immune response. In this sense, the extracellular vesicles (EVs) secreted by the parasite and the immune complexes (ICs) formed after their recognition by host IgGs (EVs-IgGs) may play an important role in the immune response during infection. The aim of the present work is to elucidate the modulation of the immune response exerted by EVs and the ICs they form by analyzing the variation in the subpopulations of small and large peritoneal macrophages after intraperitoneal inoculation in mice and to evaluate the role of the sialylation of the host IgGs in this immunomodulation. Both macrophage subpopulations were purified and subjected to cytokine expression analysis by RT-qPCR. The results showed an increase in the small peritoneal macrophage subpopulation after intraperitoneal injection of parasite EVs, but a greater increase in this subpopulation was observed when sialylated and non-sialylated ICs were injected, which was similar to inoculation with the trypomastigote stage of the parasite. The cytokine expression results showed the ability of both subpopulations to express inflammatory and non-inflammatory cytokines. These results suggest the role of free EVs in the acute phase of the disease and the possible role of immune complexes in the immune response in the chronic phase of the disease, when the levels of antibodies against the parasite allow the formation of immune complexes. The differential expression of interleukins showed after the inoculation of immune complexes formed with sialylated and non-sialylated IgGs and the interleukins expression induced by EVs, demonstrates that the IgG glycosilation is involved in the type of immune response that dominates in each of the phases of the Chagas disease.

Interleukin-18 in cancer immunology and immunotherapy

INTRODUCTION

Interleukin-18 (IL-18) is a myeloid leukocyte inflammatory mediator whose main known function is to elicit IFNγ secretion from T and NK cells.

AREAS COVERED

This function offers potential in cancer immunotherapy but as a single treatment, preclinical and clinical antitumor activities are modest. IL-18 bioactivity is chiefly downregulated by a decoy soluble receptor named IL18-binding protein (IL-18BP) that is induced by IFNγ as a negative feedback mechanism. Recent advances indicate promising efficacy of IL-18 at armoring CAR-T cells for the treatment of hematological malignancies. Preclinical research has also yielded IL-18 constructs that do not bind IL-18BP but have preserved activity on the receptor and exert markedly increased antitumor effects. Indeed, agents of this kind are undergoing clinical trials. The synergistic effects of IL-18 and IL-12 in combination to induce IFNγ are extremely potent but are toxic if systemically delivered. In mouse models, IL-12 and decoy-resistant variants of IL-18 can be efficaciously used as local treatments for tumors by exploiting mRNA intratumoral co-delivery. Moreover, antitumor T cells can be transiently engineered with mRNAs encoding this combination of cytokines to attain efficacious synergistic effects also upon intratumoral delivery.

EXPERT OPINION

IL-18 certainly holds promise for immunotherapy in combination with other agents and for local approaches.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Role of Chemokines and Inflammatory Cells in Respiratory Allergy

The idea of "one airway, one disease" has been gaining importance in the last decade. In the upper and lower airways, allergic mechanisms interact with each other. In the initial stage of respiratory allergic inflammation, allergens contact the respiratory epithelium, which produces chemokines and inflammatory factors, which cause allergic reactions by binding to the corresponding receptors and chemotactic various inflammatory cells to reach the epithelium and tissues. It also drives inflammatory cells to activate and produce more inflammatory factors, thus producing a cascade amplification effect. Inflammatory cell aggregation and activation are very complex and interact with each other in a lattice structure. By blocking the action of various chemokines, inflammatory cell aggregation is reduced, and ultimately the symptoms of respiratory allergy are alleviated. Chemokines can serve as cues for coordinated recruitment of immune cells into and out of tissues, as well as directing the spatial organization of immune cells within tissues and cellular interactions. Chemokines are critical in directing immune cell migration and thus have an important role in the direction of respiratory allergy: however, chemokines are also involved in the production and recruitment of immune cells that contribute to respiratory allergy. In this article, linking the upper and lower respiratory tracts. We review the role of the chemokine system in the respiratory immune response and discuss how respiratory disease modulates overall chemokines to shape the type and outcome of the immune response to the treatment of respiratory allergic disease so that we can further deepen our knowledge of chemokines in the direction of respiratory allergy. In the future, we can do drug research and development based on this network structure and explore new research directions.

T cell apoptosis characterizes severe Covid-19 disease

Severe SARS-CoV-2 infections are characterized by lymphopenia, but the mechanisms involved are still elusive. Based on our knowledge of HIV pathophysiology, we hypothesized that SARS-CoV-2 infection-mediated lymphopenia could also be related to T cell apoptosis. By comparing intensive care unit (ICU) and non-ICU COVID-19 patients with age-matched healthy donors, we found a strong positive correlation between plasma levels of soluble FasL (sFasL) and T cell surface expression of Fas/CD95 with the propensity of T cells to die and CD4 T cell counts. Plasma levels of sFasL and T cell death are correlated with CXCL10 which is part of the signature of 4 biomarkers of disease severity (ROC, 0.98). We also found that members of the Bcl-2 family had modulated in the T cells of COVID-19 patients. More importantly, we demonstrated that the pan-caspase inhibitor, Q-VD, prevents T cell death by apoptosis and enhances Th1 transcripts. Altogether, our results are compatible with a model in which T-cell apoptosis accounts for T lymphopenia in individuals with severe COVID-19. Therefore, a strategy aimed at blocking caspase activation could be beneficial for preventing immunodeficiency in COVID-19 patients.

Exploring the Biomaterial-Induced Secretome: Physical Bone Substitute Characteristics Influence the Cytokine Expression of Macrophages

In addition to their chemical composition various physical properties of synthetic bone substitute materials have been shown to influence their regenerative potential and to influence the expression of cytokines produced by monocytes, the key cell-type responsible for tissue reaction to biomaterials in vivo. In the present study both the regenerative potential and the inflammatory response to five bone substitute materials all based on β-tricalcium phosphate (β-TCP), but which differed in their physical characteristics (i.e., granule size, granule shape and porosity) were analyzed for their effects on monocyte cytokine expression. To determine the effects of the physical characteristics of the different materials, the proliferation of primary human osteoblasts growing on the materials was analyzed. To determine the immunogenic effects of the different materials on human peripheral blood monocytes, cells cultured on the materials were evaluated for the expression of 14 pro- and anti-inflammatory cytokines, i.e., IL-6, IL-10, IL-1β, VEGF, RANTES, IL-12p40, I-CAM, IL-4, V-CAM, TNF-α, GM-CSF, MIP-1α, Il-8 and MCP-1 using a Bio-Plex^® Multiplex System. The granular shape of bone substitutes showed a significant influence on the osteoblast proliferation. Moreover, smaller pore sizes, round granular shape and larger granule size increased the expression of GM-CSF, RANTES, IL-10 and IL-12 by monocytes, while polygonal shape and the larger pore sizes increased the expression of V-CAM. The physical characteristics of a bone biomaterial can influence the proliferation rate of osteoblasts and has an influence on the cytokine gene expression of monocytes in vitro. These results indicate that the physical structure of a biomaterial has a significant effect of how cells interact with the material. Thus, specific characteristics of a material may strongly affect the regenerative potential in vivo.

Integrated Genomic and Transcriptomic Analysis reveals key genes for predicting dual-phenotype Hepatocellular Carcinoma Prognosis

Dual-phenotype hepatocellular carcinoma (DPHCC) expresses both hepatocyte and cholangiocyte markers, and is characterized by high recurrence and low survival rates. The underlying molecular mechanisms of DPHCC pathogenesis are unclear.

We performed whole exome sequencing and RNA sequencing of three subtypes of HCC (10 DPHCC, 10 CK19-positive HCC, and 14 CK19-negative HCC), followed by integrated bioinformatics analysis, including somatic mutation analysis, mutation signal analysis, differential gene expression analysis, and pathway enrichment analysis. Cox proportional hazard regression analyses were applied for exploring survival related characteristics.

We found that mutated genes in DPHCC patients were associated with carcinogenesis and immunity, and the up-regulated genes were mainly enriched in transcription-related and cancer-related pathways, and the down-regulated genes were mainly enriched in immune-related pathways. CXCL9 was selected as the hub gene, which is associated with immune cells and survival prognosis. Our results showed that low CXCL9 expression was significantly associated with poor prognosis, and its expression was significantly reduced in DPHCC samples.

In conclusion, we explored the molecular mechanisms governing DPHCC development and progression and identified CXCL9, which influences the immune microenvironment and prognosis of DPHCC and might be new clinically significant biomarkers for predicting prognosis.

Aberrant anti-viral response of natural killer cells in severe asthma

Rhinovirus infections are the main cause of asthma exacerbations. As natural killer (NK) cells are important actors of the antiviral innate response, we aimed at evaluating the functions of NK cells from severe asthma patients in response to rhinovirus-like molecules or rhinoviruses.Peripheral blood mononuclear cells from patients with severe asthma and healthy donors were stimulated with pathogen-like molecules or with the rhinoviruses (RV)-A9 and RV-2. NK cell activation, degranulation and interferon (IFN)-γ expression were analysed.NK cells from severe asthma patients were less cytotoxic than those from healthy donors in response to toll-like receptor (TLR)3, TLR7/8 or RV-A9 but not in response to RV-2 stimulation. Furthermore, when cultured with interleukin (IL)-12+IL-15, cytokines which are produced during viral infections, NK cells from patients with severe asthma were less cytotoxic and expressed less IFN-γ than NK cells from healthy donors. NK cells from severe asthmatics exhibited an exhausted phenotype, with an increased expression of the checkpoint molecule Tim-3.Together, our findings indicate that the activation of NK cells from patients with severe asthma may be insufficient during some but not all respiratory infections. The exhausted phenotype may participate in NK cell impairment and aggravation of viral-induced asthma exacerbation in these patients.

RACK1 promotes cancer progression by increasing the M2/M1 macrophage ratio via the NF-κB pathway in oral squamous cell carcinoma

Receptor for activated C kinase 1 (RACK1) has been shown to promote oral squamous cell carcinoma (OSCC) progression, and RACK1 expression levels have been negatively correlated with prognosis in patients with OSCC. Here, we investigated the impact of RACK1 OSCC expression on the recruitment and differentiation of tumor-associated macrophages. High RACK1 expression in OSCC cells correlated with increased M2 macrophage infiltration in tumor samples from a clinical cohort study. Moreover, the combination of RACK1 expression and the M2/M1 ratio could successfully predict prognosis in OSCC. OSCC cells with high RACK1 expression inhibited the migration of THP-1 cells, promoted M2-like macrophage polarization in vitro, and increased the proportion of M2-like macrophages in a xenograft mouse model. Moreover, both M1- and M2-like macrophage polarization-associated proteins were induced in macrophages cocultured with RACK1-silenced cell supernatant. A mechanistic study revealed that the expression and secretion of C-C motif chemokine 2 (CCL2), C-C motif chemokine 5 (CCL5), interleukin-6 (IL-6), and interleukin-1 (IL-1) are closely related to RACK1 expression. In addition, blocking nuclear factor-kappa B (NF-κB) could promote M2-like macrophage polarization. These results indicate that RACK1 and the M2/M1 ratio are predictors of a poor prognosis in OSCC. RACK1 promotes M2-like polarization by regulating NF-κB and could be used as a potential therapeutic target for antitumor immunity.

Toll-like receptor 4 signaling in hematopoietic-lineage cells contributes to the enhanced activity of the human vaccine adjuvant AS01

The 3-O-desacyl-4'-monophosphoryl lipid A (MPL) activates immunity through Toll-like receptor 4 (TLR4) signaling. The Adjuvant System AS01 contains MPL and is used in the candidate malaria vaccine and the licensed zoster vaccine. Recent studies reported that AS01 adjuvant activity depends on a transient inflammation at the site of vaccination, but the role of stromal or structural cells in the adjuvant effect is unknown. We investigated this question in mouse models by assessing the role of TLR4 on hematopoietic versus resident structural cells during immunization with AS01-adjuvanted vaccines. We first established that TLR4-deficient animals had a reduced immune response to an AS01-adjuvanted vaccine. Using bone marrow chimera, we consistently found that Tlr4 expression in radio-sensitive cells, i.e., hematopoietic cells, was required for an optimal adjuvant effect on antibody and T-cell responses. At day 1 after injection, the pro-inflammatory reaction at the site of injection was strongly dependent on TLR4 signaling in hematopoietic cells. Similarly, activation of dendritic cells in muscle-draining lymph nodes was strictly associated with the radio-sensitive cells expressing Tlr4. Altogether, these data suggest that MPL-mediated TLR4-signaling in hematopoietic cells is critical in the mode of action of AS01.

Transcriptome-wide analysis of filarial extract-primed human monocytes reveal changes in LPS-induced PTX3 expression levels

Filarial nematodes modulate immune responses in their host to enable their survival and mediate protective effects against autoimmunity and allergies. In this study, we examined the immunomodulatory capacity of extracts from the human pathogenic filaria Brugia malayi (BmA) on human monocyte responses in a transcriptome-wide manner to identify associated pathways and diseases. As previous transcriptome studies often observed quiescent responses of innate cells to filariae, the potential of BmA to alter LPS driven responses was investigated by analyzing >47.000 transcripts of monocytes from healthy male volunteers stimulated with BmA, Escherichia coli LPS or a sequential stimulation of both. In comparison to ~2200 differentially expressed genes in LPS-only stimulated monocytes, only a limited number of differentially expressed genes were identified upon BmA priming before LPS re-stimulation with only PTX3↓ reaching statistical significance after correcting for multiple testing. Nominal significant differences were reached for metallothioneins↑, MMP9↑, CXCL5/ENA-78↑, CXCL6/GCP-2↑, TNFRSF21↓, and CCL20/MIP3α↓ and were confirmed by qPCR or ELISA. Flow cytometric analysis of activation markers revealed a reduced LPS-induced expression of HLA-DR and CD86 on BmA-primed monocytes as well as a reduced apoptosis of BmA-stimulated monocytes. While our experimental design does not allow a stringent extrapolation of our results to the development of filarial pathology, several genes that were identified in BmA-primed monocytes had previously been associated with filarial pathology, supporting the need for further research.

Myeloid-restricted ablation of Shp2 restrains melanoma growth by amplifying the reciprocal promotion of CXCL9 and IFN-γ production in tumor microenvironment

The Src homology 2 domain-containing protein tyrosine phosphatase 2 (Shp2) is generally considered to be an oncogene owing to its ability in enhancing the malignancy of multiple types of tumor cells; however, its role in modulating tumor immunity remains largely elusive. Here, we reported that myeloid-restricted ablation of Shp2 suppressed melanoma growth. Mechanistically, loss of Shp2 potentiates macrophage production of CXCL9 in response to IFN-γ and tumor cell-derived cytokines, thereby facilitating the tumor infiltration of IFN-γ-producing T cells that could in turn support CXCL9 production within tumor microenvironment. Collectively, our findings highlight a causative role of myeloid Shp2 in dampening T cell-mediated antitumor immunity by restraining the macrophage/CXCL9-T cell/IFN-γ feedback loop. Thus, targeting macrophage Shp2 may help to create a Th1-dominant tumor immune microenvironment.

CpG Oligodeoxynucleotides Induce Differential Cytokine and Chemokine Gene Expression Profiles in Dapulian and Landrace Pigs

Oligodeoxynucleotides containing unmethylated CpG motifs (CpG ODN) mimic the immunostimulatory activity of microbial DNA by interacting with Toll-like receptor 9 (TLR9) to activate both the innate and adaptive immune responses in different species. However, few studies have been published to compare the effects of CpG ODN on different pig breeds. Therefore, in this study, whole blood gene expression profiles of DPL and Landrace pigs treated with CpG ODN were studied using RNA-seq technology. Five Hundred differentially expressed genes (DEGs) were identified between the two breeds. DPL pigs had significantly higher number of immune-relevant DEGs than the Landrace pigs after CpG ODN treatment. Pathway analysis showed that cytokine-cytokine receptor interaction and chemokine signaling pathway were the major enriched pathways of the immune-relevant DEGs. Further in vitro experiments showed that PBMCs of the DPL pigs had significantly higher levels of TLR9 mRNA than those of the Landrace pigs, both before and after CpG ODN stimulation. Cytokine and chemokine induction in the PBMCs of both breeds were also measured after CpG ODN stimulation. Our data showed that mRNA levels of cytokines (IFNα, IL8, IL12 p40) and chemokines (CXCL9, CXCL13) were significantly higher in the PBMCs of the DPL pigs than those of the Landrace pigs. Taken together, our data provide new information regarding the pig breed difference in response to CpG ODN stimulation and that higher levels of TLR9 mRNA in DPL pigs may be a major contributor for disease resistance.

Changes in Neuronal Excitability by Activated Microglia: Differential Na(+) Current Upregulation in Pyramid-Shaped and Bipolar Neurons by TNF-α and IL-18

Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here, we demonstrate that the addition of 5% microglia activated by 1 μg/ml lipopolysaccharides (LPS) to hippocampal cultures upregulates Na⁺ current densities (I_NavD) of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β) decreases I_NavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α), a major cytokine released by activated microglia, upregulated I_NavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells, the upregulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the upregulation of I_NavD in bipolar cells, whereas in pyramid-shaped cells, increases in I_NavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18), are released from activated microglia, we tested potential effects of IL-18 on I_NavD in both cell types. Exposure to 5–10 ng/ml IL-18 for 4 days increased I_NavD in both pyramid-shaped as well as bipolar neurons, albeit the dose–response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines, microglial cells upregulate Na⁺ current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released, this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger upregulation of I_NavD in response to TNF-α as well as respond to smaller concentrations of IL-18, our results offer an explanation for the finding, that in certain conditions of brain inflammations periods of dizziness are followed by epileptic seizures.

IMQ-induced skin inflammation in mice is dependent on IL-1R1 and MyD88 signaling but independent of the NLRP3 inflammasome

The pathogenesis of inflammatory skin diseases such as psoriasis involves the release of numerous proinflammatory cytokines, including members of the IL-1 family. Here we report overexpression of IL-1α, IL-1β, and IL-1 receptor antagonist mRNA, associated to expression of IL-23p19, IL-17A, and IL-22 in skin cells, upon topical application of the TLR7 agonist imiquimod (IMQ) in C57BL/6J mice. IMQ-induced skin inflammation was partially reduced in mice deficient for both IL-1α/IL-1β or for IL-1 receptor type 1 (IL-1R1), but not in IL-1α- or IL-1β-deficient mice, demonstrating the redundant activity of IL-1α and IL-1β for skin inflammation. NLRP3 or apoptosis-associated Speck-like protein containing a Caspase recruitment domain-deficient mice had no significant reduction of skin inflammation in response to IMQ treatment, mainly due to the redundancy of IL-1α. However, IMQ-induced skin inflammation was abolished in the absence of MyD88, the adaptor protein shared by IL-1R and TLR signaling pathways. These results are consistent with the TLR7 dependence of IMQ-induced skin inflammation. Thus, IL-1R1 contributes to the IMQ-induced skin inflammation, and disruption of MyD88 signaling completely abrogates this response.

β-Catenin/TCF-4 signaling regulates susceptibility of macrophages and resistance of monocytes to HIV-1 productive infection

Cells of the monocyte/macrophage lineage are an important target for HIV-1 infection. They are often at anatomical sites linked to HIV-1 transmission and are an important vehicle for disseminating HIV-1 throughout the body, including the central nervous system. Monocytes do not support extensive productive HIV-1 replication, but they become more susceptible to HIV-1infection as they differentiate into macrophages. The mechanisms guiding susceptibility of HIV-1 replication in monocytes versus macrophages are not entirely clear. We determined whether endogenous activity of β-catenin signaling impacts differential susceptibility of monocytes and monocyte-derived macrophages (MDMs) to productive HIV-1 replication. We show that monocytes have an approximately 4-fold higher activity of β-catenin signaling than MDMs. Inducing β-catenin in MDMs suppressed HIV-1 replication by 5-fold while inhibiting endogenous β-catenin signaling in monocytes by transfecting with a dominant negative mutant for the downstream effector of β- catenin (TCF-4) promoted productive HIV-1 replication by 6-fold. These findings indicate that β-catenin/TCF-4 is an important pathway for restricted HIV-1 replication in monocytes and plays a significant role in potentiating HIV-1 replication as monocytes differentiate into macrophages. Targeting this pathway may provide a novel strategy to purge the latent reservoir from monocytes/macrophages, especially in sanctuary sites for HIV-1 such as the central nervous system.

Interleukin-18 increases TLR4 and mannose receptor expression and modulates cytokine production in human monocytes

Interleukin-18 is a proinflammatory cytokine belonging to the interleukin-1 family of cytokines. This cytokine exerts many unique biological and immunological effects. To explore the role of IL-18 in inflammatory innate immune responses, we investigated its impact on expression of two toll-like receptors (TLR2 and TLR4) and mannose receptor (MR) by human peripheral blood monocytes and its effect on TNF-α, IL-12, IL-15, and IL-10 production. Monocytes from healthy donors were stimulated or not with IL-18 for 18 h, and then the TLR2, TLR4, and MR expression and intracellular TNF-α, IL-12, and IL-10 production were assessed by flow cytometry and the levels of TNF-α, IL-12, IL-15, and IL-10 in culture supernatants were measured by ELISA. IL-18 treatment was able to increase TLR4 and MR expression by monocytes. The production of TNF-α and IL-10 was also increased by cytokine treatment. However, IL-18 was unable to induce neither IL-12 nor IL-15 production by these cells. Taken together, these results show an important role of IL-18 on the early phase of inflammatory response by promoting the expression of some pattern recognition receptors (PRRs) that are important during the microbe recognition phase and by inducing some important cytokines such as TNF-α and IL-10.

The chemokine CXCL9 exacerbates chemotherapy-induced acute intestinal damage through inhibition of mucosal restitution

PURPOSE

Acute intestinal damage induced by chemotherapeutic agent is often a dose-limiting factor in clinical cancer therapy. The aim of this study was to investigate the effect of chemokine CXCL9 on the intestinal damage after chemotherapy and explore the therapeutic potential of anti-CXCL9 agents.

METHODS

In vitro cell proliferation assay was performed with a non-tumorigenic human epithelial cell line MCF10A. Multiple pathway analysis was carried out to explore the pathway that mediated the effect of CXCL9, and the corresponding downstream effector was identified with enzyme-linked immunosorbent assays. Chemotherapy-induced mouse model of intestinal mucositis was prepared by a single injection of the chemotherapeutic agent 5-fluorouracil (5-FU). In vivo expression of cxcl9 and its receptor cxcr3 in intestinal mucosa after chemotherapy was determined by quantitative real-time PCR. Therapeutic treatment with anti-CXCL9 antibodies was investigated to confirm the hypothesis that CXCL9 can contribute to the intestinal epithelium damage induced by chemotherapy.

RESULTS

CXCL9 inhibited the proliferation of MCF10A cells by activating phosphorylation of p70 ribosomal S6 kinase (p70S6K), which further promotes the secretion of transforming growth factor beta (TGF-β) as the downstream effector. A blockade of phospho-p70S6K with inhibitor abolished the effect of CXCL9 on MCF10A cells and reduced the secretion of TGF-β. The expression levels of cxcl9 and cxcr3 were significantly up-regulated in intestinal mucosa after 5-FU injection. Neutralizing elevated CXCL9 with anti-CXCR9 antibodies successfully enhanced reconstitution of intestinal mucosa and improved the survival rate of mice that received high-dose chemotherapy.

CONCLUSIONS

CXCL9 inhibits the proliferation of epithelial cells via phosphorylation of p70S6K, resulting in the excretion of TGF-β as downstream mediator. CXCL9/CXCR3 interaction can exacerbate chemotherapeutic agent-induced intestinal damage, and anti-CXCL9 agents are potential novel therapeutic candidates for promoting mucosal restitution.

Enhancement of phagocytosis and cytotoxicity in macrophages by tumor-derived IL-18 stimulation

Inoculation of mice with the murine NFSA cell line caused the formation of large tumors with necrotic tumor cores. FACS analysis revealed accumulations of CD11b⁺ cells in the tumors. Microarray analysis indicated that the NFSA cells expressed a high level of the pro-inflammatory factor interleukin-18 (il-18), which is known to play a critical role in macrophages. However, little is known about the physiological function of IL-18-stimulated macrophages. Here, we provide direct evidence that IL-18 enhances the phagocytosis of RAW264 cells and peritoneal macrophages, accompanied by the increased expression of tumor necrosis factor (tnf-α), interleukin-6 (il-6) and inducible nitric oxide synthase (Nos2). IL-18-stimulated RAW264 cells showed an enhanced cytotoxicity to endothelial F-2 cells via direct cell-to-cell interaction and the secretion of soluble mediators. Taken together, our results demonstrate that tumor-derived IL-18 plays an important role in the phagocytosis of macrophages and that IL-18-stimulated macrophages may damage tumor endothelial cells. [BMB Reports 2014; 47(5): 286-291]

Single low-dose rHuIL-12 safely triggers multilineage hematopoietic and immune-mediated effects

Background

Recombinant human interleukin 12 (rHuIL-12) regulates hematopoiesis and cell-mediated immunity. Based on these hematopoietic and immunomodulatory activities, a recombinant human IL-12 (rHuIL-12) is now under development to address the unmet need for a medical countermeasure against the hematopoietic syndrome of the acute radiation syndrome (HSARS) that occurs in individuals exposed to lethal radiation, and also to serve as adjuvant therapy that could provide dual hematopoietic and immunotherapeutic benefits in patients with cancer receiving chemotherapy. We sought to demonstrate in healthy subjects the safety of rHuIL-12 at single, low doses that are appropriate for use as a medical countermeasure for humans exposed to lethal radiation and as an immunomodulatory anti-cancer agent.

Methods

Two placebo-controlled, double-blinded studies assessed the safety, tolerability, pharmacokinetics and pharmacodynamics of rHuIL-12. The first-in-human (FIH) dose-escalation study randomized subjects to single subcutaneous injections of placebo or rHuIL-12 at 2, 5, 10, and 20 μg doses. Due to toxicity, dose was reduced to 15 μg and then to 12 μg. The phase 1b expansion study randomized subjects to the highest safe and well tolerated dose of 12 μg.

Results

Thirty-two subjects were enrolled in the FIH study: 4 active and 2 placebo at rHuIL-12 doses of 2, 5, 10, 12, and 15 μg; 1 active and 1 placebo at 20 μg. Sixty subjects were enrolled in the expansion study: 48 active and 12 placebo at 12 μg dose of rHuIL-12. In both studies, the most common adverse events (AEs) related to rHuIL-12 were headache, dizziness, and chills. No immunogenicity was observed. Elimination of rHuIL-12 was biphasic, suggesting significant distribution into extravascular spaces. rHuIL-12 triggered transient changes in neutrophils, platelets, reticulocytes, lymphocytes, natural killer cells, and CD34⁺ hematopoietic progenitor cells, and induced increases in interferon-γ and C-X-C motif chemokine 10.

Conclusion

A single low dose of rHuIl-12 administered subcutaneously can elicit hematological and immune-mediated effects without undue toxicity. The safety and the potent multilineage hematopoietic/immunologic effects triggered by low-dose rHuIL-12 support the development of rHuIL-12 both as a radiation medical countermeasure and as adjuvant immunotherapy for cancer.

Trial registration

ClinicalTrials.gov: NCT01742221

The lack of a big picture in tuberculosis: the clinical point of view, the problems of experimental modeling and immunomodulation. The factors we should consider when designing novel treatment strategies

This short review explores the large gap between clinical issues and basic science, and suggests why tuberculosis research should focus on redirect the immune system and not only on eradicating Mycobacterium tuberculosis bacillus. Along the manuscript, several concepts involved in human tuberculosis are explored in order to understand the big picture, including infection and disease dynamics, animal modeling, liquefaction, inflammation and immunomodulation. Scientists should take into account all these factors in order to answer questions with clinical relevance. Moreover, the inclusion of the concept of a strong inflammatory response being required in order to develop cavitary tuberculosis disease opens a new field for developing new therapeutic and prophylactic tools in which destruction of the bacilli may not necessarily be the final goal.

Interleukin 18: friend or foe in cancer

In the last few years, the field of tumor immunology has significantly expanded and its boundaries, never particularly clear, have become less distinct. Although the immune system plays an important role in controlling tumor growth, it has also become clear that tumor growth can be promoted by inflammatory immune responses. A good example that exemplifies the ambiguous role of the immune system in cancer progression is represented by interleukin 18 (IL-18) that was first identified as an interferon-γ-inducing factor (IGIF) involved in T helper type-1 (Th1) immune response. The expression and secretion of IL-18 have been observed in various cell types from immune cells to circulating cancer cells. In this review we highlighted the multiple roles played by IL-18 in immune regulation, cancer progression and angiogenesis and the clinical potential that may result from such understanding.

Dissimilar cytokine patterns in different human liver and colon cancer cell lines

An accurate and simultaneous estimate of cellular levels of a large cytokine number is very useful to obtain information about an organ dysfunction leading to cancer because through the understanding of the evolution of cytokine patterns we can recognize and predict the disease progression. Cancer cell lines are commonly used to study the cancer microenvironment, to analyze their chemosensitivity and carcinogenesis as well as to test in vitro the effect of molecules, such as drugs or anti-oxidants, on the inflammation status and its progression. We noted that various cell lines commonly used as a model for studies on liver and colon cancer possess different patterns of cytokines. This aspect may generate data not comparable in laboratories using different cell lines; thus, to investigate the origin of these abnormalities we compared the cell lines HepG2 and Huh7, and HT-29 and HCT-116, for liver and colon cancer, respectively. In this context we have evaluated and compared the levels of cytokines, chemokines and growth factors in the supernatants of these cellular lines. Our aim was to identify what cytokines were significantly different correlating similarities and differences to the specific inflammation status of each cellular model of cancer.

The effect of cell subset isolation method on gene expression in leukocytes

Multiple scientific disciplines require the isolation of specific subsets of blood cells from patient samples for gene expression analysis by microarray or RNA-sequencing, preserving disease- or treatment-related signatures. However, little is known with respect to the impact of different cell isolation methods on gene expression and the effects of positive selection, negative selection, and fluorescence activated cell sorting (FACS) have not previously been assessed in parallel. To address this knowledge gap, CD4+ T cells, CD8+ T cells, B cells, and monocytes were isolated from blood samples from five independent donors using positive immunomagnetic selection, negative immunomagnetic selection, and FACS. We hypothesized that positive selection and FACS would yield higher purity but may have an impact on gene expression since both methods utilize antibodies that bind surface receptors of the cell type of interest. Moreover, FACS might upregulate stress response genes due to passage of the cells through the sorter. Microarray gene expression data were generated and subjected to unsupervised clustering and differential gene expression analysis. Surprisingly, these analyses revealed that gene expression signatures were more similar between cells isolated by negative selection and FACS compared to cells isolated by positive selection. Moreover, genes that are involved in the response to stress generally had the highest expression in cells isolated by negative or positive selection and not FACS. Thus, FACS is the recommended method for isolation of leukocyte subsets for gene expression studies since this method results in the purest subset populations and does not appear to induce a stress response.

The role of chemokines in acute and chronic hepatitis C infection

Hepatitis C imposes a significant burden on global healthcare. Chronic infection is associated with progressive inflammation of the liver which typically manifests in cirrhosis, organ failure and cancer. By virtue of elaborate evasion strategies, hepatitis C virus (HCV) succeeds as a persistent human virus. It has an extraordinary capacity to subvert the immune response enabling it to establish chronic infections and associated liver disease. Chemokines are low molecular weight chemotactic peptides that mediate the recruitment of inflammatory cells into tissues and back into the lymphatics and peripheral blood. Thus, they are central to the temporal and spatial distribution of effector and regulatory immune cells. The interactions between chemokines and their cognate receptors help shape the immune response and therefore, have a major influence on the outcome of infection. However, chemokines represent a target for modulation by viruses including the HCV. HCV is known to modulate chemokine expression in vitro and may therefore enable its survival by subverting the immune response in vivo through altered leukocyte chemotaxis resulting in impaired viral clearance and the establishment of chronic low-grade inflammation. In this review, the roles of chemokines in acute and chronic HCV infection are described with a particular emphasis placed on chemokine modulation as a means of immune subversion. We provide an in depth discussion of the part played by chemokines in mediating hepatic fibrosis while addressing the potential applications for these chemoattractants in prognostic medicine.

Restriction of HIV-1 replication in primary macrophages by IL-12 and IL-18 through the upregulation of SAMHD1

Monocyte-derived macrophages (MDM) can polarize into different subsets depending on the environment and the activation signal to which they are submitted. Differentiation into macrophages allows HIV-1 strains to infect cells of the monocytic lineage. In this study, we show that culture of monocytes with a combination of IL-12 and IL-18 led to macrophage differentiation that was resistant to HIV-1 infection. In contrast, M-CSF-derived MDM were readily infected by HIV-1. When monocytes were differentiated in the presence of M-CSF and then further treated with IL-12/IL-18, cells became resistant to infection. The restriction on HIV-1 replication was not dependent on virus entry or coreceptor expression, as vesicular stomatitis virus-pseudotyped HIV-1 replication was also blocked by IL-12/IL-18. The HIV-1 restriction factor sterile α motif and HD domain-containing protein-1 (SAMHD1) was significantly overexpressed in IL-12/IL-18 MDM compared with M-CSF MDM, and degradation of SAMHD1 by RNA interference or viral-like particles carrying the lentiviral protein Vpx restored HIV-1 infectivity of IL-12/IL-18 MDM. SAMHD1 overexpression induced by IL-12/IL-18 was not dependent on IFN-γ. Thus, we conclude that IL-12 and IL-18 may contribute to the response against HIV-1 infection through the induction of restriction factors such as SAMHD1.

Rational design of HIV vaccines and microbicides: report of the EUROPRISE annual conference 2011

Europrise is a Network of Excellence supported by the European Commission within the 6th Framework programme from 2007 to 2012. The Network has involved over 50 institutions from 13 European countries together with 3 industrial partners and 6 African countries. The Network encompasses an integrated program of research, training, dissemination and advocacy within the field of HIV vaccines and microbicides. A central and timely theme of the Network is the development of the unique concept of co-usage of vaccines and microbicides. Training of PhD students has been a major task, and some of these post-graduate students have here summarized novel ideas emanating from presentations at the last annual Europrise meeting in Prague. The latest data and ideas concerning HIV vaccine and microbicide studies are included in this review; these studies are so recent that the majority have yet to be published. Data were presented and discussed concerning novel immunisation strategies; microbicides and PrEP (alone and in combination with vaccines); mucosal transmission of HIV/SIV; mucosal vaccination; novel adjuvants; neutralizing antibodies; innate immune responses; HIV/SIV pathogenesis and disease progression; new methods and reagents. These – necessarily overlapping topics - are comprehensively summarised by the Europrise students in the context of other recent exciting data.

Cytokinome profile of patients with type 2 diabetes and/or chronic hepatitis C infection

Both type 2 diabetes (T2D) and chronic hepatitis C (CHC) infection are associated with increased risk of developing hepatocellular carcinoma (HCC). Cytokines are known to play an important role not only in the mechanisms of insulin resistance and glucose disposal defects but also in the pathological processes occurring in the liver during viral infection. We evaluated the serum levels of many cytokines, chemokines, adipokines and growth factors in patients with type 2 diabetes, CHC, CHC-related cirrhosis, CHC and type 2 diabetes and CHC-related cirrhosis and type 2 diabetes by BioPlex assay. The obtained data evidenced that the serum levels of some proteins are significantly up-regulated in all the patients or in those with only one disease and are often higher, even if in different amounts, when both diseases are associated. In particular, our results can be useful for the clinical monitoring of patients because they give specific information in regard to the progression from CHC to LC and CHD to LCD. Moreover, some molecules have shown significant correlations with clinical/biochemical data, suggesting the possibility to define mini-panels that can be used as specific markers for the different disease staging. However, our observations demonstrate that an integrated approach is much more powerful than isolated measurements to evaluate specific stages of these two complex pathologies (type 2 diabetes and chronic CHC hepatitis) alone or when they are concomitant in a patient. In fact it has emerged as an accurate, simple, specific, noninvasive, reproducible and less expensive method that, in future, could be included in routine clinical practice to monitor the association of type 2 diabetes and/or CHC to liver cirrhosis and, possibly, to cancer, and to improve the prognosis of these diseases.

Ginsenoside metabolite compound K differentially antagonizing tumor necrosis factor-α-induced monocyte-endothelial trafficking

Human leukocyte endothelial adhesion and transmigration occur in the early stage of the pathogenesis of atherosclerosis. Vascular endothelial cells are targeted by pro-inflammatory cytokines modulating many gene proteins responsible for cell adhesion, thrombosis and inflammatory responses. This study examined the potential of compound K to inhibit the pro-inflammatory cytokine TNF-α induction of monocyte adhesion onto TNF-α-activated human umbilical vein endothelial cells (HUVEC). HUVEC were cultured with 10ng/ml TNF-α with individual ginsenosides of Rb1, Rc, Re, Rh1 and compound K (CK). Ginsenosides at doses of ⩽50μM did not show any cytotoxicity. TNF-α induced THP-1 monocyte adhesion to HUVEC, and such induction was attenuated by Rh1 and CK. Consistently, CK suppressed TNF-α-induced expression of HUVEC adhesion molecules of VCAM-1, ICAM-1 and E-selectin, and also Rh1 showed a substantial inhibition. Rh1 and CK dampened induction of counter-receptors, α4/β1 integrin VLA-4 and αL/β2 integrin LFA-1 in TNF-α-treated THP-1 cells. Additionally, CK diminished THP-1 secretion of MMP-9 required during transmigration, inhibiting transendothelial migration of THP-1 cells. CK blunted TNF-α-promoted IL-8 secretion of HUVEC and CXCR1 expression of THP-1 monocytes. Furthermore, TNF-α-activated endothelial IκB phosphorylation and NF-κB nuclear translocation were disturbed by CK, and TNF-α induction of α4/β1 integrin was abrogated by the NF-κB inhibitor SN50. These results demonstrate that CK exerts anti-atherogenic activity with blocking leukocyte endothelial interaction and transmigration through negatively mediating NF-κB signaling.

Functional genomics of endothelial cells treated with anti-angiogenic or angiopreventive drugs

Angiogenesis is a highly regulated physiological process that has been studied in considerable detail given its importance in several chronic pathologies. Many endogenous factors and hormones intervene in the regulation of angiogensis and classical as well as targeted drugs have been developed for its control. Angiogenesis inhibition has come off the bench and entered into clinical application for cancer therapy, particularly for metastatic disease. While the clinical benefit is currently in terms of months, preclinical data suggest that novel drugs and drug combinations could lead to substantial improvement. The many targets of endogenous angiogenesis inhibitors reflect the complexity of the process; in contrast, current clinical therapies mainly target the vascular endothelial growth factor system. Cancer chemopreventive compounds can retard tumor insurgence and delay or prevent metastasis and many of these molecules hinder angiogenesis, a mechanism that we termed angioprevention. Angiopreventive drugs appear to prevalently act through the inhibition of the pro-inflammatory and anti-apoptotic player NFkappaB, thus contrasting inflammation dependent angiogenesis. Relatively little is known concerning the effects of these angiogenesis inhibitors on gene expression of endothelial cells, the main target of many of these molecules. Here we provide an exhaustive list of anti-angiogenic molecules, and summarize their effects, where known, on the transcriptome and functional genomics of endothelial cells. The regulation of specific genes can be crucial to preventive or therapeutic intervention. Further, novel targets might help to circumvent resistance to anti-angiogenic therapy. The studies we review are relevant not only to cancer but also to other chronic degenerative diseases involving endothelial cells, such as cardiovascular disorders, diabetes, rheumatoid arthritis and retinopaties, as well as vessel aging.

Endometrial caspase 1 and interleukin-18 expression during the estrous cycle and peri-implantation period of porcine pregnancy and response to early exogenous estrogen administration

BACKGROUND

The role for endometrial secretion of cytokines during the establishment of pregnancy in a number of mammals is well established. The current study determined endometrial expression of caspase 1 (CASP1) and interleukin-18 (IL18) during the estrous cycle and early pregnancy, and following early estrogen administration, which induces conceptus loss during early development in pigs.

METHODS

Gilts were hysterectomized on either D 0, 5, 10, 12, 15 and 18 of the estrous cycle, or D 10, 12, 15 or 18 of pregnancy. The abundance of endometrial CASP1 mRNA was unaffected by day of the estrous cycle, however there was a 6 and 10-fold increase in expression on D 15 and 18 of pregnancy. Endometrial expression of IL18 mRNA increased 5-fold between D 10 to 18 in cyclic and pregnant gilts. Total recoverable IL18 in uterine flushings was greater in pregnant compared to cyclic gilts on D 15 and 18.In the second experiment, mated gilts were treated with either corn oil (CO) or estrogen (E) on D 9 and 10 and hysterectomized on either D 10, 12, 13, 15 or 17 of pregnancy. The current study localizes the presence of CASP1 to the epithelial layer of the endometrium for the first time. Further, a day x treatment interaction was detected for endometrial CASP1 mRNA and protein abundance as E stimulated an earlier increase on D 13 compared to CO gilts. Although IL18 mRNA expression remained unaltered from the E treatment, protein abundance was significantly attenuated on D 15 and 18 in response to E treatment.

CONCLUSIONS

Endometrial expression of CASP1 and IL18 is associated with establishment of pregnancy in pigs. Alteration of CASP1 and IL18 following premature exposure of the uterus to estrogen during early pregnancy may contribute to conceptus loss between Days 15 to 18 of pregnancy.

Disruption of Th2 immunity results in a gender-specific expansion of IL-13 producing accessory NK cells during helminth infection

Host gender has previously been identified as a determining factor in the resolution of Trichuris muris infection in mice lacking IL-4 (IL-4KO BALB/c). Worm expulsion in these mice is delayed, but occurs in females. In this study we were able to demonstrate delayed expulsion occurs at day 26 post infection and is associated with the production of the key Th2-associated cytokine IL-13 by both CD4(+) T cells and an auxiliary DX5(+) NK cell source, as well as a concurrent reduction in proinflammatory cytokines. NK cell number was comparably increased in both sexes, but NK cells from male mice were found to express higher levels of the chemokine receptor CXCR3. Depletion of CD4(+) T cells completely prevented parasite expulsion, whereas loss of NK cells resulted in a mild, but significant delay. Furthermore, IL-18 is a cytokine with the capacity to enhance both Th1 and Th2 responses found to be dispensable for worm expulsion in female mice but was a key factor for the suppression of the Th2 response in male IL-4KO mice. In contrast neutralization of IFN-gamma resulted in a complete restoration of typical wild-type BALB/c expulsion kinetics. This study sheds further light on the role of accessory NK cells in supplementing the IL-13-driven immune response when normal Th2 immunity is disrupted, and further identifies host gender as a key factor in determining the generation of "NK cell help".

Immune response to Mycobacterium tuberculosis and identification of molecular markers of disease

The complex molecular events that occur within the host during the establishment of a Mycobacterium tuberculosis infection are poorly defined, thus preventing identification of predictive markers of disease progression and state. To identify such molecular markers during M. tuberculosis infection, global changes in transcriptional response in the host were assessed using mouse whole genome arrays. Bacterial load in the lungs, the lesions associated with infection, and gene expression profiling was performed by comparing normal lung tissue to lungs from mice collected at 20, 40, and 100 days after aerosol infection with the H37Rv strain of M. tuberculosis. Quantitative, whole lung gene expression identified signature profiles defining different signaling pathways and immunological responses characteristic of disease progression. This includes genes representing members of the interferon-associated gene families, chemokines and cytokines, MHC, and NOS2, as well as an array of cell surface markers associated with the activation of T cells, macrophages, and dendritic cells that participate in immunity to M. tuberculosis infection. More importantly, several gene transcripts encoding proteins that were not previously associated with the host response to M. tuberculosis infection, and unique molecular markers associated with disease progression and state, were identified.

Secretion of interferon-gamma by human macrophages demonstrated at the single-cell level after costimulation with interleukin (IL)-12 plus IL-18

The interferon (IFN)-gamma component of the immune response plays an essential role in combating infectious and non-infectious diseases. Induction of IFN-gamma secretion by human T and natural killer (NK) cells through synergistic costimulation with interleukin (IL)-12 and IL-18 in the adaptive immune responses against pathogens is well established, but induction of similar activity in macrophages is still controversial, with doubts largely focusing on contamination of macrophages with NK or T cells in the relevant experiments. The possible contribution of macrophages to the IFN response is, however, an important factor relevant to the pathogenesis of many diseases. To resolve this issue, we analysed the production of IFN-gamma at the single-cell level by immunohistochemistry and by enzyme-linked immunosorbent spot (ELISPOT) analysis and unequivocally demonstrated that human macrophages derived from monocytes in vitro through stimulation with a combination of IL-12 and IL-18 or with macrophage colony-stimulating factor (M-CSF) were able to produce IFN-gamma when further stimulated with a combination of IL-12 and IL-18. In addition, naturally activated alveolar macrophages immediately secreted IFN-gamma upon treatment with IL-12 and IL-18. Therefore, human macrophages in addition to lymphoid cells contribute to the IFN-gamma response, providing another link between the innate and acquired immune responses.

HIV transfer between CD4 T cells does not require LFA-1 binding to ICAM-1 and is governed by the interaction of HIV envelope glycoprotein with CD4

Background

Cell-to-cell HIV transmission requires cellular contacts that may be in part mediated by the integrin leukocyte function antigen (LFA)-1 and its ligands intercellular adhesion molecule (ICAM)-1, -2 and -3. The role of these molecules in free virus infection of CD4 T cells or in transinfection mediated by dendritic cells (DC) has been previously described. Here, we evaluate their role in viral transmission between different HIV producing cells and primary CD4 T cells.

Results

The formation of cellular conjugates and subsequent HIV transmission between productively infected MOLT cell lines and primary CD4 T cells was not inhibited by a panel of blocking antibodies against ICAM-1, ICAM-3 and α and β chains of LFA-1. Complete abrogation of HIV transmission and formation of cellular conjugates was only observed when gp120/CD4 interactions were blocked. The dispensable role of LFA-1 in HIV transmission was confirmed using non-lymphoid 293T cells, lacking the expression of adhesion molecules, as HIV producing cells. Moreover, HIV transmission between infected and uninfected primary CD4 T cells was abrogated by inhibitors of gp120 binding to CD4 but was not inhibited by blocking LFA-1 binding to ICAM-1 or ICAM-3. Rather, LFA-1 and ICAM-3 mAbs enhanced HIV transfer. All HIV producing cells (including 293T cells) transferred HIV particles more efficiently to memory than to naive CD4 T cells.

Conclusion

In contrast to other mechanisms of viral spread, HIV transmission between infected and uninfected T cells efficiently occurs in the absence of adhesion molecules. Thus, gp120/CD4 interactions are the main driving force of the formation of cellular contacts between infected and uninfected CD4 T cells whereby HIV transmission occurs.

Cellular targets of interleukin-18 in rheumatoid arthritis

Recent data are presented which indicate a critical role for interleukin (IL)-18 in rheumatoid arthritis (RA). The T cells and macrophages invading the synovium or in the synovial fluid are the chief cellular targets of IL-18 in RA. Neutrophils, dendritic cells and endothelial cells may also be cellular mediators of IL-18. The direct effect of IL-18 on fibroblast-like synoviocytes or chondrocytes may not be essential or important. In RA, IL-18, which is mainly produced by macrophages, activates T cells and macrophages to produce proinflammatory cytokines, chemokines, adhesion molecules and RANKL which, in turn, perpetuate chronic inflammation and induce bone and cartilage destruction.

Induction of interleukins IL-6 and IL-8 by siRNA

The HIV-1 co-receptor CCR5 has been thought a relevant target for small interfering RNA (siRNA)-based therapeutics. However, recent findings suggest that siRNA can stimulate innate cytokine responses in mammals. All siRNA agents tested were able to down-regulate the expression of CCR5, albeit with different efficiency (51-74% down-regulation), block HIV-induced syncytia formation between HIV-1 BaL-infected and uninfected CD4(+) cells or block single-round HIV-1 infection as measured by a luciferase reporter assay (46-83% inhibition). Conversely, siRNA directed against CCR5 did not affect replication of a vesicular stomatitis virus (VSV) pseudotyped virus, suggesting that inhibition of HIV replication was specific to CCR5 down-regulation. However, two of four siRNA tested were able to induce the production of interleukin (IL) IL-6 (sixfold induction) and IL-8 (ninefold induction) but no interferon (IFN)-alpha, IFN-beta, IFN-gamma, tumour necrosis factor (TNF)-alpha, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, RANTES, IL-1beta, IL-10 or IL-12p70 cytokine induction was noted. In the absence of detectable IFN-alpha, IL-6 or IL-8 may represent markers of non-specific effects triggered by siRNA.