IL-3 in dendritic cell development and function: a comparison with GM-CSF and IL-4

Dark pigmentation and related low FMOD expression increase IL-3 and facilitate plasmacytoid dendritic cell maturation

According to epidemiological research, skin autoimmune diseases are more prevalent among black Americans. We postulated that pigment-producing melanocytes may contribute to local immune regulation in the microenvironment. We examined murine epidermal melanocytes in vitro to determine the role of pigment production in immune responses mediated by dendritic cell (DC) activation. Our study revealed that darkly pigmented melanocytes produce more IL-3 and the pro-inflammatory cytokines, IL-6 and TNF-α, and consequently induce plasmacytoid DC (pDC) maturation. Additionally, we demonstrate that low pigment-associated fibromodulin (FMOD) interferes with cytokine secretion and subsequent pDC maturation.

The synergistic and enhancive effects of IL-6 and M-CSF to expand and differentiate functional dendritic cells from human monocytes under serum-free condition

BACKGROUND

Dendritic cells (DCs) are differentiated from monocytes, and have a strong ability to perform phagocytosis, present antigens and activate T cell immune response. Therefore, DCs are one of the key factors in fighting cancer in immunotherapy, and it is an important issue to develop a serum-free system for DC differentiation and expansion in vitro for clinical application.

RESULTS

In this study, IL-6 and M-CSF were determined and a concentration combination of cytokines was optimized to develop an optimal DC serum-free differentiation medium (SF-DC Optimal) that can effectively differentiate CD14⁺ monocytes into CD40⁺CD209⁺ DCs. After differentiation, the morphology, growth kinetics, surface antigen expression, phagocytosis ability, cytokine secretion, mixed lymphocyte reaction and stimulation for maturation of the differentiated DCs were checked and confirmed. Importantly, this research is the first report finding that the addition an extra low concentration of IL-6 and M-CSF exhibited a synergistic effect with GM-CSF and IL-4 to generate higher numbers and more fully functional DCs than the addition of GM-CSF and IL-4 only under serum-free condition.

CONCLUSION

A large number of functional DCs can be generated by using SF-DC Optimal medium and provide an alternative source of DCs for related basic research and clinical applications.

IL-3 regulates the differentiation of pathogenic Th17 cells

IL-17 producing Th17 cells play an important role in pathogenesis of rheumatoid arthritis (RA). Aberrant immune activation due to imbalance between Th17 and regulatory T (Treg) cells is associated with development of RA and other autoimmune diseases. Targeting pathogenic Th17 cells and their associated molecules is emerging as a promising strategy to treat and reverse RA. Here, we demonstrate that IL-3 inhibits the differentiation of Th17 cells and promotes the development of Treg cells in IL-2-dependent manner. In IL-2 knockout mice, we observed that IL-3 has no effect on differentiation of both Th17 and Treg cells. In addition, IL-3 decreases pathogenic IL-17A⁺ TNF-α⁺ , IL-17A⁺ IFN-γ⁺ and IL-23R⁺ Th17 cells, secretion of GM-CSF and IFN-γ, and osteoclastogenesis when presented in the culture together with Th-17 polarizing cytokines. Mechanistically, IL-3 regulates the development of Th17 cells through inhibition of STAT3 phosphorylation. IL-3 treatment significantly decreases the pathogenic Th17 cell responses and arthritic scores in mouse model of RA. Importantly, IL-3 inhibits differentiation of human Th17 cells. Thus, our results suggest a novel therapeutic role of IL-3 in regulation of Th17 cell-mediated pathophysiology of RA. This article is protected by copyright. All rights reserved.

IL-3 in the development and function of basophils

The β common chain (βc) cytokine family includes granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3) and IL-5, all of which use βc as key signaling receptor subunit. GM-CSF, IL-3 and IL-5 have specific roles as hematopoietic growth factors. IL-3 binds with high affinity to the IL-3 receptor α (IL-3Rα/CD123) and then associates with the βc subunit. IL-3 is mainly synthesized by different subsets of T cells, but is also produced by several other immune [basophils, dendritic cells (DCs), mast cells, etc.] and non-immune cells (microglia and astrocytes). The IL-3Rα is also expressed by immune (basophils, eosinophils, mast cells, DCs, monocytes, and megacaryocytes) and non-immune cells (endothelial cells and neuronal cells). IL-3 is the most important growth and activating factor for human and mouse basophils, primary effector cells of allergic disorders. IL-3-activated basophils and mast cells are also involved in different chronic inflammatory disorders, infections, and several types of cancer. IL-3 induces the release of cytokines (i.e., IL-4, IL-13, CXCL8) from human basophils and preincubation of basophils with IL-3 potentiates the release of proinflammatory mediators and cytokines from IgE- and C5a-activated basophils. IL-3 synergistically potentiates IL-33-induced mediator release from human basophils. IL-3 plays a pathogenic role in several hematologic cancers and may contribute to autoimmune and cardiac disorders. Several IL-3Rα/CD123 targeting molecules have shown some efficacy in the treatment of hematologic malignancies.

Laser nanobubbles induce immunogenic cell death in breast cancer

Recent advances in immunotherapy have highlighted a need for therapeutics that initiate immunogenic cell death in tumors to stimulate the body's immune response to cancer. This study examines whether laser-generated bubbles surrounding nanoparticles ("nanobubbles") induce an immunogenic response for cancer treatment. A single nanosecond laser pulse at 1064 nm generates micron-sized bubbles surrounding gold nanorods in the cytoplasm of breast cancer cells. Cell death occurred in cells treated with nanorods and irradiated, but not in cells with irradiation treatment alone. Cells treated with nanorods and irradiation had increased damage-associated molecular patterns (DAMPs), including increased expression of chaperone proteins human high mobility group box 1 (HMGB1), adenosine triphosphate (ATP), and heat shock protein 70 (HSP70). This enhanced expression of DAMPs led to the activation of dendritic cells. Overall, this treatment approach is a rapid and highly specific method to eradicate tumor cells with simultaneous immunogenic cell death signaling, showing potential as a combination strategy for immunotherapy.

Assessment of faithful interleukin-3 production by novel bicistronic interleukin-3 reporter mice

Interleukin-3 (IL-3) is an important hematopoietic growth factor and immunregulatory cytokine. Although activated T helper cells represent a main source of IL-3, other cell types have been reported to express this cytokine. However, precise identification and quantification of the cells that produce IL-3 in vivo have not been performed. Therefore, we used a CRISPR/Cas approach to engineer mice containing a bicistronic mRNA linking a readily identifiable reporter, enhanced green fluorescent protein (ZsGreen1), to IL-3 expression. To characterize these novel reporter mice, we first examined ZsGreen1 expression by CD4 T cells subsets primed and activated in vitro. We found that activated Th1 cells expressed ∼4-fold higher levels of ZsGreen1 as compared to Th0 and Th2 cells. Endogenous IL-3 expression remained intact although reporter Th1 cells secreted ∼33 % less IL-3 than similarly activated wild-type cells. To characterize the ability of reporter mice to accurately mark IL-3-producing cells in vivo, we infected mice with Nippostrongylus brasiliensis. Low but significant numbers of ZsGreen1+ CD4 T cells were detected in the mesenteric lymph nodes and lung following both primary and secondary infection. No difference in basophil and intestinal mast cell numbers were observed between infected reporter and wild-type mice indicating that reporter mice secreted IL-3 levels in vivo that results in IL-3-driven biological activities which are indistinguishable from those observed in corresponding wild-type mice. These IL-3 reporter mice will be a valuable resource to investigate IL-3-dependent immune responses in vivo.

Development of innate immunity in chicken embryos and newly hatched chicks: a disease control perspective

Newly hatched chickens are confronted by a wide array of pathogenic microbes because their adaptive immune defences have limited capabilities to control these pathogens. In such circumstances, and within this age group, innate responses provide a degree of protection. Moreover, as the adaptive immune system is relatively naïve to foreign antigens, synergy with innate defences is critical. This review presents knowledge on the ontogeny of innate immunity in chickens pre-hatch and early post-hatch and provides insights into possible interventions to modulate innate responses early in the life of the bird. As in other vertebrate species, the chicken innate immune system which include cellular mediators, cytokine and chemokine repertoires and molecules involved in antigen detection, develop early in life. Comparison of innate immune systems in newly hatched chickens and mature birds has revealed differences in magnitude and quality, but responses in younger chickens can be boosted using innate immune system modulators. Functional expression of pattern recognition receptors and several defence molecules by innate immune system cells of embryos and newly hatched chicks suggests that innate responses can be modulated at this stage of development to combat pathogens. Improved understanding of innate immune system ontogeny and functionality in chickens is critical for the implementation of sound and safe interventions to provide long-term protection against pathogens. Next-generation tools for studying genetic and epigenetic regulation of genes, functional metagenomics and gene knockouts can be used in the future to explore and dissect the contributions of signalling pathways of innate immunity and to devise more efficacious disease control strategies.

Ex vivo dendritic cell generation-A critical comparison of current approaches

Dendritic cells (DCs) are professional antigen-presenting cells, required for the initiation of naïve and memory T cell responses and regulation of adaptive immunity. The discovery of DCs in 1973, which culminated in the Nobel Prize in Physiology or Medicine in 2011 for Ralph Steinman and colleagues, initially focused on the identification of adherent mononuclear cell fractions with uniquely stellate dendritic morphology, followed by key discoveries of their critical immunologic role in initiating and maintaining antigen-specific immunity and tolerance. The medical promise of marshaling these key capabilities of DCs for therapeutic modulation of antigen-specific immune responses has guided decades of research in hopes to achieve genuine physiologic partnership with the immune system. The potential uses of DCs in immunotherapeutic applications include cancer, infectious diseases, and autoimmune disorders; thus, methods for rapid and reliable large-scale production of DCs have been of great academic and clinical interest. However, difficulties in obtaining DCs from lymphoid and peripheral tissues, low numbers and poor survival in culture, have led to advancements in ex vivo production of DCs, both for probing molecular details of DC function as well as for experimenting with their clinical utility. Here, we review the development of a diverse array of DC production methodologies, ranging from cytokine-based strategies to genetic engineering tools devised for enhancing DC-specific immunologic functions. Further, we explore the current state of DC therapies in clinic, as well as emerging insights into physiologic production of DCs inspired by existing therapies.

Human Dendritic Cells: Ontogeny and Their Subsets in Health and Disease

Dendritic cells (DCs) are a type of cells derived from bone marrow that represent 1% or less of the total hematopoietic cells of any lymphoid organ or of the total cell count of the blood or epithelia. Dendritic cells comprise a heterogeneous population of cells localized in different tissues where they act as sentinels continuously capturing antigens to present them to T cells. Dendritic cells are uniquely capable of attracting and activating naïve CD4⁺ and CD8⁺ T cells to initiate and modulate primary immune responses. They have the ability to coordinate tolerance or immunity depending on their activation status, which is why they are also considered as the orchestrating cells of the immune response. The purpose of this review is to provide a general overview of the current knowledge on ontogeny and subsets of human dendritic cells as well as their function and different biological roles.

Dendritic cell-based vaccination: powerful resources of immature dendritic cells against pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PAC) has a poor prognosis. One treatment approach, investigated here, is to reinforce antitumor immunity. Dendritic cells (DCs) are essential for the development and regulation of adaptive host immune responses against tumors. A major role for DCs may be as innate tumoricidal effector cells. We explored the efficacy of vaccination with immature (i)DCs, after selecting optimal conditions for generating immunostimulatory iDCs. We used two models, C57BL/6Jrj mice with ectopic tumors induced by the PAC cell line, Panc02, and genetically engineered (KIC) mice developing PAC. Therapeutic iDC-vaccination resulted in a significant reduction in tumor growth in C57BL/6Jrj mice and prolonged survival in KIC mice. Prophylactic iDC-vaccination prevented subcutaneous tumor development. These protective effects were long-lasting in Panc02-induced tumor development, but not in melanoma. iDC-vaccination impacted the immune status of the hosts by greatly increasing the percentage of CD8⁺ T-cells, and natural killer (NK)1.1⁺ cells, that express granzyme B associated with Lamp-1 and IFN-γ. Efficacy of iDC-vaccination was CD8⁺ T-cell-dependent but NK1.1⁺ cell-independent. We demonstrated the ability of DCs to produce peroxynitrites and to kill tumor cells; this killing activity involved peroxynitrites. Altogether, these findings make killer DCs the pivotal actors in the beneficial clinical outcome that accompanies antitumor immune responses. We asked whether efficacy can be improved by combining DC-vaccination with the FOLFIRINOX regimen. Combined treatment significantly increased the lifespan of KIC mice with PAC. Prolonged treatment with FOLFIRINOX clearly augmented this beneficial effect. Combining iDC-vaccination with FOLFIRINOX may therefore represent a promising therapeutic option for patients with PAC.

Is There a Role for Hematopoietic Growth Factors During Sepsis?

Sepsis is a complex syndrome characterized by simultaneous activation of pro- and anti-inflammatory processes. After an inflammatory phase, patients present signs of immunosuppression and possibly persistent inflammation. Hematopoietic growth factors (HGFs) are glycoproteins that cause immune cells to mature and/or proliferate. HGFs also have a profound effect on cell functions and behavior. HGFs play crucial role in sepsis pathophysiology and were tested in several clinical trials without success to date. This review summarizes the role played by HGFs during sepsis and their potential therapeutic role in the Management of sepsis-related immune disturbances.

Optimization of Ex Vivo Murine Bone Marrow Derived Immature Dendritic Cells: A Comparative Analysis of Flask Culture Method and Mouse CD11c Positive Selection Kit Method

12-14 days of culturing of bone marrow (BM) cells containing various growth factors is widely used method for generating dendritic cells (DCs) from suspended cell population. Here we compared flask culture method and commercially available CD11c Positive Selection kit method. Immature BMDCs' purity of adherent as well as suspended cell population was generated in the decreasing concentration of recombinant-murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF) in nontreated tissue culture flasks. The expression of CD11c, MHCII, CD40, and CD86 was measured by flow cytometry. We found significant difference (P < 0.05) between the two methods in the adherent cells population but no significant difference was observed between the suspended cell populations with respect to CD11c+ count. However, CD11c+ was significantly higher in both adhered and suspended cell population by culture method but kit method gave more CD11c+ from suspended cells population only. On the other hand, using both methods, immature DC expressed moderate level of MHC class II molecules as well as low levels of CD40 and CD86. Our findings suggest that widely used culture method gives the best results in terms of yield, viability, and purity of BMDCs from both adherent and suspended cell population whereas kit method works well for suspended cell population.

GM-CSF Monocyte-Derived Cells and Langerhans Cells As Part of the Dendritic Cell Family

Dendritic cells (DCs) and macrophages (Mph) share many characteristics as components of the innate immune system. The criteria to classify the multitude of subsets within the mononuclear phagocyte system are currently phenotype, ontogeny, transcription patterns, epigenetic adaptations, and function. More recently, ontogenetic, transcriptional, and proteomic research approaches uncovered major developmental differences between Flt3L-dependent conventional DCs as compared with Mphs and monocyte-derived DCs (MoDCs), the latter mainly generated in vitro from murine bone marrow-derived DCs (BM-DCs) or human CD14⁺ peripheral blood monocytes. Conversely, in vitro GM-CSF-dependent monocyte-derived Mphs largely resemble MoDCs whereas tissue-resident Mphs show a common embryonic origin from yolk sac and fetal liver with Langerhans cells (LCs). The novel ontogenetic findings opened discussions on the terminology of DCs versus Mphs. Here, we bring forward arguments to facilitate definitions of BM-DCs, MoDCs, and LCs. We propose a group model of terminology for all DC subsets that attempts to encompass both ontogeny and function.

Dendritic cells in the host response to implanted materials

The role of dendritic cells (DCs) and their targeted manipulation in the body's response to implanted materials is an important and developing area of investigation, and a large component of the emerging field of biomaterials-based immune engineering. The key position of DCs in the immune system, serving to bridge innate and adaptive immunity, is facilitated by rich diversity in type and function and places DCs as a critical mediator to biomaterials of both synthetic and natural origins. This review presents current views regarding DC biology and summarizes recent findings in DC responses to implanted biomaterials. Based on these findings, there is promise that the directed programming of application-specific DC responses to biomaterials can become a reality, enabling and enhancing applications almost as diverse as the larger field of biomaterials itself.

Pathogenic Inflammation and Its Therapeutic Targeting in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE, lupus) is a highly complex and heterogeneous autoimmune disease that most often afflicts women in their child-bearing years. It is characterized by circulating self-reactive antibodies that deposit in tissues, including skin, kidneys, and brain, and the ensuing inflammatory response can lead to irreparable tissue damage. Over many years, clinical trials in SLE have focused on agents that control B- and T-lymphocyte activation, and, with the single exception of an agent known as belimumab which targets the B-cell survival factor BAFF, they have been disappointing. At present, standard therapy for SLE with mild disease is the agent hydroxychloroquine. During disease flares, steroids are often used, while the more severe manifestations with major organ involvement warrant potent, broad-spectrum immunosuppression with cyclophosphamide or mycophenolate. Current treatments have severe and dose-limiting toxicities and thus a more specific therapy targeting a causative factor or signaling pathway would be greatly beneficial in SLE treatment. Moreover, the ability to control inflammation alongside B-cell activation may be a superior approach for disease control. There has been a recent focus on the innate immune system and associated inflammation, which has uncovered key players in driving the pathogenesis of SLE. Delineating some of these intricate inflammatory mechanisms has been possible with studies using spontaneous mouse mutants and genetically engineered mice. These strains, to varying degrees, exhibit hallmarks of the human disease and therefore have been utilized to model human SLE and to test new drugs. Developing a better understanding of the initiation and perpetuation of disease in SLE may uncover suitable novel targets for therapeutic intervention. Here, we discuss the involvement of inflammation in SLE disease pathogenesis, with a focus on several key proinflammatory cytokines and myeloid growth factors, and review the known outcomes or the potential for targeting these factors in SLE.

Mucopolysaccharide diseases: a complex interplay between neuroinflammation, microglial activation and adaptive immunity

Mucopolysaccharide (MPS) diseases are lysosomal storage disorders (LSDs) caused by deficiencies in enzymes required for glycosaminoglycan (GAG) catabolism. Mucopolysaccharidosis I (MPS I), MPS IIIA, MPS IIIB and MPS VII are deficient in the enzymes α-L-Iduronidase, Heparan-N-Sulphatase, N-Acetylglucosaminidase and Beta-Glucuronidase, respectively. Enzyme deficiency leads to the progressive multi-systemic build-up of heparan sulphate (HS) and dermatan sulphate (DS) within cellular lysosomes, followed by cell, tissue and organ damage and in particular neurodegeneration. Clinical manifestations of MPS are well established; however as lysosomes represent vital components of immune cells, it follows that lysosomal accumulation of GAGs could affect diverse immune functions and therefore influence disease pathogenesis. Theoretically, MPS neurodegeneration and GAGs could be substantiating a threat of danger and damage to alert the immune system for cellular clearance, which due to the progressive nature of MPS storage would propagate disease pathogenesis. Innate immunity appears to have a key role in MPS; however the extent of adaptive immune involvement remains to be elucidated. The current literature suggests a complex interplay between neuroinflammation, microglial activation and adaptive immunity in MPS disease.

Characterisation of the T cell and dendritic cell repertoire in a murine model of mucopolysaccharidosis I (MPS I)

BACKGROUND

Mucopolysaccharidosis I (MPS I) is a metabolic disorder caused by α-L-Iduronidase (IDUA) deficiency, resulting in lysosomal accumulation of heparan (HS) and dermatan sulphate (DS). This has been reported in microglia, yet currently the effect of IDUA deficiency on T cells and dendritic cells (DC) and their functionality in disease pathogenesis remains unclear.

METHODS

Peripheral blood was collected from 3 month old C57BL/6 MPS I (n = 11) and wildtype (WT) (n = 6) mice. T cell and DC phenotype and functional characteristics were identified by flow cytometry.

RESULTS

MPS I mice exhibited a reduction in DC (p = <0.001) along with CD8+ cytotoxic (p = 0.01) and CD4+ T helper (p = 0.032) cells, compared to WT controls. MPS I DC displayed a significant decrease in cell surface CD123 (p = 0.02) and CD86 (p = 0.006) expression. Furthermore, CD45RB expression was significantly reduced on T helper cells in the MPS I population (p = 0.019).

CONCLUSION

We report a reduction in circulating DC and T cells in the MPS I mouse; indicative of adaptive immune dysfunction. DC reduction may occur in response to down-regulation of the IL-3 receptor (CD123), necessary for DC survival. We also report down-regulation of cell surface CD86, a molecule required for T cell co-stimulation. T helper cell down-regulation of CD45RB is redolent of an anti-inflammatory phenotype with poor proliferative capacity. The definitive causes of our findings and the consequences and role that these findings play in the pathogenesis of MPS are unclear, but may be in response to lysosomal storage of unmetabolized HS and DS.

Inflammasome activation and inhibition in primary murine bone marrow-derived cells, and assays for IL-1α, IL-1β, and caspase-1

Through its ability to control the proteolytic maturation and secretion of interleukin-1 family cytokines, the inflammasome occupies a central role in the activation of inflammation and also influences the shaping of adaptive immunity. Since it affects a multitude of different immune responses from autoinflammatory diseases to host defense, vaccine efficacy, and even cancer, it has become of interest to many researchers. Here, we describe a straightforward method for inflammasome assays in primary murine bone marrow--derived myeloid cells. The protocol encompasses cell handling, inflammasome activation and inhibition, as well as the detection of IL-1β, caspase-1, and IL-1α by ELISA and Western blot.

Cellular therapies supplement: the role of granulocyte macrophage colony-stimulating factor and dendritic cells in regulatory T-cell homeostasis and expansion

Regulatory T cells are a subset of T cells with inhibitory function that are critical for protection against autoimmunity and immunopathology. A failure to maintain adequate regulatory T-cell numbers in the periphery results in autoimmune manifestations, highlighting the importance of the continuous maintenance of peripheral regulatory T cells. The cellular and molecular requirements for regulatory T-cell homeostasis and expansion are not fully understood but involve a complex interplay among dendritic cells, conventional T cells, and regulatory T cells. In addition, soluble factors such as the cytokine granulocyte macrophage colony-stimulating factor may play a role in enhancing these interactions. In this review, we discuss our National Blood Foundation-funded studies relating to the role of granulocyte macrophage colony-stimulating factor and dendritic cells in controlling regulatory T-cell homeostasis and expansion.

Measuring the inflammasome

Inflammasomes are multiprotein complexes whose activity has been implicated in physiological and pathological inflammation. The hallmarks of inflammasome activation are the secretion of the mature forms of Caspase-1 and IL-1β from cells of the innate immune system. This protocol covers the methods required to study inflammasome activation using mouse bone marrow-derived dendritic cells (BMDCs) as a model system. The protocol includes the generation and handling of BMDCs, the stimulation of BMDCs with established Nlrp3 inflammasome activators, and the measurement of activation by both ELISA and western blot. These methods can be useful for the study of potential inflammasome activators, and of the signaling pathways involved in inflammasome activation. General considerations are provided that may help in the design and optimization of modified methods for the study of other types of inflammasomes and in other cell types.

Nano-characterization of Jagged-1-educated dendritic cells

Jagged-1-educated dendritic cells (DCs) are of distinct phenotypes different from Lipopolysaccharide (LPS)-educated DCs. However, to date, little is known as to nano-features of Jagged-1-educated DCs. In this study, nanostructure of Jagged-1-educated DCs was observed through atomic force microscopy. Our results showed that the volume, surface area and width of Jagged-1-educated DCs, and the number of protrusion, pseudopodia and lamellapodia on the surface of Jagged-1-educated DCs were significantly more than those of GM-CSF-induced DCs, but less than those of LPS-educated DCs. Compared with GM-CSF-induced DCs, the roughness on the surface of Jagged-1-educated DCs was greatly increased, similar to LPS-educated DCs, but the particle size and number of them on the membrane were markedly less than the latter. The change of DC nanostructure caused by Jagged-1 was abrogated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycinet-butyl ester, a γ-secretase inhibitor of Notch signaling pathway. Compared to LPS-educated DCs, Jagged-1-educated DCs highly expressed NICD, Deltex-1 and Hes-1 proteins, moderately produced IL-12, but not IFN-γ, and the level of CD40 molecules on the surface of them was much lower, suggesting that Jagged-1-educated DCs are in a semi-mature status and may have unique functions distinguished from LPS-educated DCs.

Comparison of immature and mature bone marrow-derived dendritic cells by atomic force microscopy

A comparative study of immature and mature bone marrow-derived dendritic cells (BMDCs) was first performed through an atomic force microscope (AFM) to clarify differences of their nanostructure and adhesion force. AFM images revealed that the immature BMDCs treated by granulocyte macrophage-colony stimulating factor plus IL-4 mainly appeared round with smooth surface, whereas the mature BMDCs induced by lipopolysaccharide displayed an irregular shape with numerous pseudopodia or lamellapodia and ruffles on the cell membrane besides becoming larger, flatter, and longer. AFM quantitative analysis further showed that the surface roughness of the mature BMDCs greatly increased and that the adhesion force of them was fourfold more than that of the immature BMDCs. The nano-features of the mature BMDCs were supported by a high level of IL-12 produced from the mature BMDCs and high expression of MHC-II on the surface of them. These findings provide a new insight into the nanostructure of the immature and mature BMDCs.

sRAGE induces human monocyte survival and differentiation

The receptor for advanced glycation end products (RAGE) is produced either as a transmembrane or soluble form (sRAGE). Substantial evidence supports a role for RAGE and its ligands in disease. sRAGE is reported to be a competitive, negative regulator of membrane RAGE activation, inhibiting ligand binding. However, some reports indicate that sRAGE is associated with inflammatory disease. We sought to define the biological function of sRAGE on inflammatory cell recruitment, survival, and differentiation in vivo and in vitro. To test the in vivo impact of sRAGE, the recombinant protein was intratracheally administered to mice, which demonstrated monocyte- and neutrophil-mediated lung inflammation. We also observed that sRAGE induced human monocyte and neutrophil migration in vitro. Human monocytes treated with sRAGE produced proinflammatory cytokines and chemokines. Our data demonstrated that sRAGE directly bound human monocytes and monocyte-derived macrophages. Binding of sRAGE to monocytes promoted their survival and differentiation to macrophages. Furthermore, sRAGE binding to cells increased during maturation, which was similar in freshly isolated mouse monocytes compared with mature tissue macrophages. Because sRAGE activated cell survival and differentiation, we examined intracellular pathways that were activated by sRAGE. In primary human monocytes and macrophages, sRAGE treatment activated Akt, Erk, and NF-kappaB, and their activation appeared to be critical for cell survival and differentiation. Our data suggest a novel role for sRAGE in monocyte- and neutrophil-mediated inflammation and mononuclear phagocyte survival and differentiation.

Expression of Th2-skewed pathology mediators in monocyte-derived type 2 of dendritic cells (DC2)

The information conveyed from dendritic cells (DCs) to naïve CD4(+) T cells has crucial influence on their differentiation toward effector T cells. In an effort to identify DC-derived molecules directly contributing to T cell differentiation, we searched for molecules distinctively expressed between two DC subtypes, which were differentiated from peripheral monocytes by cultivation with GM-CSF (for DC1) or IL-3 (for DC2) in the presence of IL-4 and had the ability to induce naïve T cells to differentiate into Th1 or Th2 cells, respectively. As the first step to address this issue, we subtracted DC1 transcripts from those of DC2 and compiled the gene profile dominantly expressed in DC2, whose products are known to reside in other than the nucleus. Intriguingly, many of them were molecules involved in Th2-skewed disease pathologies, such as FN1, ITGAE, GPNMB, PLAUR, FPRL2, LILRB4, SERPINE1, ALOX15, TBXAS1, NCF2, CCL3, IL1RN, SPARC, and STAB1, suggesting that DCs function not only as antigen presenting cells but also as producers of Th2 pathology specific milieus leading to disease deteriorations. We also found that expressions of CYP27A1, PPAP2B, RSAD2, and ABCC3 were up-regulated in DC2, implying their significant function in Th2-deviated states. The identification of differentially expressed genes between DC subtypes provides new insights into their functions and our comparative gene expression profile will be highly useful for the identification of DC-derived key molecules for T cell differentiation.

Basal and inducible expression of the thiol-sensitive ART2.1 ecto-ADP-ribosyltransferase in myeloid and lymphoid leukocytes

ADP-ribosylation of cell surface proteins in mammalian cells is a post-translational modification by which ecto-ADP-ribosyltransferases (ARTs) transfer ADP-ribose from extracellular NAD to protein targets. The ART2 locus at murine chromosome 7 encompasses the tandem Art2a and Art2b genes that encode the distinct ART2.1 and ART2.2 proteins. Although both ecto-enzymes share 80% sequence identity, ART2.1 activity is uniquely regulated by an allosteric disulfide bond that is reducible in the presence of extracellular thiols, such as cysteine and glutathione, that accumulate in hypoxic and ischemic tissues. Previous studies have characterized the expression of ART2.1 and ART2.2 in murine T lymphocytes but not in other major classes of lymphoid and myeloid leukocytes. Here, we describe the expression of ART2.1 activity in a wide range of freshly isolated or tissue-cultured murine myeloid and lymphoid leukocytes. Spleen-derived macrophages, dendritic cells (DC), and B cells constitutively express ART2.1 as their predominant ART while spleen T cells express both ART2.1 and the thiol-independent ART2.2 isoform. Although bone-marrow-derived macrophages (BMDM) and dendritic cells (BMDC) constitutively express ART2.1 at low levels, it is markedly up-regulated when these cells are stimulated in vitro with IFNbeta or IFNgamma. ART2.1 expression and activity in splenic B cells is modestly up-regulated during incubation in vitro for 24 h, a condition that promotes B cell apoptosis. This increase in ART2.1 is attenuated by IL-4 (a B cell survival factor), but is not affected by IFNbeta/gamma, suggesting a possible induction of ART2.1 as an ancillary response to B cell apoptosis. In contrast, ART2.1 and ART2.2, which are highly expressed in freshly isolated splenic T cells, are markedly down-regulated when purified T cells are incubated in vitro for 12-24 h. Studies with the BW5147 mouse thymocyte line verified basal expression of ART2.1 and ART2.2, as in primary spleen T cells, and demonstrated that both isoforms can be up-regulated when T cells are maintained in the presence of IFNs. Comparison of the surface proteins which are ADP-ribosylated by ART2.1 in the different leukocyte subtypes indicated both shared and cell-specific proteins as ART2.1 substrates. The LFA-1 integrin, a major target for ART2.2 in T cells, is also ADP-ribosylated by the ART2.1 expressed in macrophages. Thus, ART2.1, in contrast to ART2.2, is expressed in a broad range of myeloid and lymphoid leukocytes. The thiol redox-sensitive nature of this ecto-enzyme suggests an involvement in purinergic signaling that occurs in the combined context of inflammation and hypoxia/ischemia.

Inhibitory effects of rat bone marrow-derived dendritic cells on naïve and alloantigen-specific CD4+ T cells: a comparison between dendritic cells generated with GM-CSF plus IL-4 and dendritic cells generated with GM-CSF plus IL-10

Background

Unlike mouse immature bone marrow (BM)-derived dendritic cells (DC), rat immature BMDC have not been thoroughly characterised in vitro for the mechanisms underlying their suppressive effect. To better characterise these mechanisms we therefore analysed the phenotypes and immune inhibitory properties of rat BMDC generated with GM-CSF plus IL-4 (= IL-4 DC) and with GM-CSF plus IL-10 (= IL-10 DC).

Results

Both IL-4 DC and IL-10 DC exhibited lower surface expression of MHC class II and costimulatory molecules than mature splenic DC. They had a strong inhibitory effect on responsive T cells in vitro and despite their weak function as antigen-presenting cells they induced anergic T cells. However, only anergic T cells induced by IL-4 DC had a suppressive effect on responsive T cells. Induction of suppressive/tolerogenic T cells by IL-4 DC required direct contact between antigen-specific T cells and IL-4 DC. In addition, IL-4 DC and IL-10 DC prolonged allograft survival in an antigen-specific manner.

Conclusion

A unique phenotype of immature BMDC was isolated from the cultures. The mechanisms underlying the suppressive effect may be caused by their inability to deliver adequate costimulatory signals for T-cell activation. In addition, IL-4 DC but not IL-10 DC induce anergic T cells with suppressive function. This indicates that IL-4 DC and IL-10 DC may differ in the quality of their costimulation although no differences in the surface expression of costimulatory molecules were found.

Survival of monocytes and macrophages and their role in health and disease

Macrophages are versatile cells involved in health and disease. These cells act as scavengers to rid the body of apoptotic and senescent cells and debris through their phagocytic function. Although this is a primary function of these cells, macrophages play vital roles in inflammation and repair of damaged tissue. Macrophages secrete a large number of cytokines, chemokines and growth factors that recruit and activate a variety of cell types to inflamed tissue compartments. These cells are also critical in cell-mediated immunity and in the resolution of inflammation. Since macrophages, and their precursors, blood monocytes, are important in regulating and resolving inflammation, prolonged cellular survival in tissue compartments could be detrimental. Thus, factors that regulate the fate of monocyte and macrophage survival are important in cellular homeostasis. In this article, we will explore stimuli and the intracellular pathways important in regulating macrophage survival and implication in human disease.

An improved method to generate equine dendritic cells from peripheral blood mononuclear cells: divergent maturation programs by IL-4 and LPS

Equine dendritic cells (eqDC) can be generated from peripheral blood monocytes by propagation in GM-CSF and IL-4. Despite similarities with the generation of human DC, we found significant improvements for eqDC generation and functional influences on eqDC maturation. The fractionation of peripheral blood mononuclear cells (PBMC) by two subsequent gradients at densities of 1.090 and 1.077 as well as an adherence step in AIM V((R)) medium on dishes coated with extracellular matrix components (Primaria) improved the purity and yield of DC. After 3 days, eqDC cultures with GM-CSF alone developed into three subsets of (i) MHC II(neg) cells, (ii) MHC II(low) immature, endocytic cells and (iii) MHC II(high) spontaneously mature, non-endocytic DC. The immature DC fraction of the GM-CSF cultures matured, as detected by MHC II up-regulation, upon LPS exposure overnight. DC cultures in GM-CSF plus IL-4 resulted in higher cell yields, a loss of the immature MHC II(low) population but increased mature MHC II(high) DC, suggesting maturation. However, the MHC II(high) DC fraction was still endocytically active and did not lose their endocytic function after LPS treatment. They marginally up-regulated MHC II expression but this did not result in an enhanced stimulation of an allogeneic mixed lymphocyte reaction. However, LPS treatment clearly induced mRNA for IL-12p35 and p40, which was not observed by addition of IL-4 alone. Together our data indicate that IL-4 and LPS induce two different maturation programs. IL-4 induces a semi-maturation where the cells are still endocytic, which can be further matured to secrete cytokines in a second step by LPS.

CD4+CD25+ T regulatory cells induced by LPS-activated bone marrow dendritic cells suppress experimental autoimmune uveoretinitis in vivo

BACKGROUND

Tolerance-inducing DC are considered to be less mature than immunogenic DC, but the conditions promoting a less mature DC phenotype are not clear. We have previously shown that lipopolysaccharide (LPS) can have differential effects on DC function depending on the timing of DC exposure to LPS. Here, we show that early LPS-activated bone marrow derived DC (early DC, eDC), when administered subcutaneously to mice in vivo, promote tolerance to EAU induced via immunisation with interphotoreceptor retinol binding protein (IRBP) peptide 161-180. The effect correlates with the failure of eDC to secrete IL-12, and appears to be mediated in part via expansion of naturally occurring CD4+ CD25+ T regulatory cells (Tregs), which also mediate suppression of EAU on adoptive transfer to naive mice followed by immunization with autoantigen.

METHODS

Immature DC were prepared from BMDC cultures. Early DC (eDC) and late DC (lDC) for tolerance experiments were obtained by differential timing of LPS addition and their cytokine secretion profile was analyzed. eDC and lDC were subcutaneously injected into mice. From the dLN CD4+ CD25+ GITR+ T regulatory cells found to express FoxP3 were isolated and transferred into mice prior to immunisation with IRBP. The immune response was scored by histopathology. Tregs were characterized in vitro by intracellular staining, cytokine secretion assay and transwell experiments.

RESULTS

eDC secrete IL-10 but no IL-12 or IFNgamma. When injected subcutaneously into naive mice, they expand the population of CD4+ CD25(+high) GITR+ T cells expressing FoxP3 in the dLN, thus increasing the total number of IL-10 producing cells. eDC induced Tregs inhibit CD4+ CD25- T effector cell proliferation by a contact dependent process, and both eDC and Tregs suppress retinal damage when adoptively transferred.

CONCLUSIONS

We suggest that DC maturation may be necessary for both tolerance and immunity, but differential levels of activation and/or cytokine production direct the outcome of DC-T cell interaction and this is determined by IL-12 production. T regulatory cells induced in vivo by contact with eDC are able to suppress disease in the EAU model by adoptive transfer.

GMCSF in the absence of other cytokines sustains human dendritic cell precursors with T cell regulatory activity and capacity to differentiate into functional dendritic cells

Dendritic cell precursors, from human peripheral blood, express epitopes reactive with monoclonal antibodies specific for the empty conformation of HLA-DR1. Expression is substantially up-regulated during GMCSF-induced differentiation to immature dendritic cells, but is strongly down-regulated by IL-4. In the conventional protocol for in vitro generation of human dendritic cells from monocyte precursors, both GMCSF and IL-4 are used together, with IL-4 thought to have an effect on preventing macrophage outgrowth but not substantially altering the dendritic cell maturation pathway, whereas conventional protocols for generation of murine dendritic cells use GMCSF alone. We characterized human monocytes cultured in the presence of GMCSF and in the absence of IL-4, and found that the resultant cultures are stable for long periods in vitro, and have T cell stimulatory and immunodulatory activity characteristic of immature dendritic cells. Their response to maturation stimuli is weak in the absence of IL-4 but these cells retain the ability to differentiate into fully functional mature dendritic cells upon IL-4 treatment. We suggest that these cells may provide a useful model to investigate tolerogenic function as a developmental feature of DC and to understand molecular events involved in IL-4 priming for maturation.

Production of IL-12, IL-23 and IL-27p28 by bone marrow-derived conventional dendritic cells rather than macrophages after LPS/TLR4-dependent induction by Salmonella Enteritidis

Induction of the interleukin-12 (IL-12) cytokine family comprising IL-12, IL-23, IL-27, and IL-12p40 by intracellular pathogens is required for orchestration of cell-mediated immune responses. Macrophages (MPhi) have been shown to be a source of IL-12 following TLR4-dependent activation by Salmonella (S.). In this study another antigen-presenting cell type, the conventional dendritic cell (cDC), was analyzed and its cytokine responses compared with those of MPhi. We generated bone marrow-derived conventional dendritic cells (BMDC) and macrophages (BMMPhi) by incubating murine bone marrow cells with supernatants containing granulocyte/macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF), respectively. Stimulation of BMDC and BMMPhi with S. enterica serovar Enteritidis (SE) or LPS resulted in the release of IL-12 and IL-23 by BMDC but not by BMMPhi. Furthermore, BMDC secreted approx. 20-fold more IL-12p40 and IL-27p28 than BMMPhi. However, BMDC and BMMPhi produced similar levels of IL-10. Using BMDC originating from wild-type (wt), TLR2(def) and TLR4(def) mice, we show that in BMDC the induction of IL-12, IL-23, and IL-27p28 by SE is dependent on TLR4, whereas low-level production of p40 is also mediated by pattern recognition receptors (PRR) other than TLR4. Interestingly, LPS- and SE-provoked responses of BMDC were remarkably similar indicating that LPS is the primary danger molecule of SE. Taken together, our results point to cDC rather than MPhi as the major producers of the IL-12 family members during in vitro infection with SE. The mechanisms of recognition of SE, however, appear to be the same for cDC and MPhi.

Hepatitis C is associated with perturbation of intrahepatic myeloid and plasmacytoid dendritic cell function

BACKGROUND/AIMS

In most cases infection with hepatitis C results in chronic infection as a consequence of viral subversion and failed anti-viral immune responses. The suggestion that dendritic cells are defective in chronic HCV infection led us to investigate the phenotype and function of liver-derived myeloid (mDC) and plasmacytoid (pDC) dendritic cells in patients with chronic HCV infection.

METHODS

Liver DCs were isolated without expansion in cytokines from human liver allowing us to study unmanipulated tissue-resident DCs ex vivo.

RESULTS

Compared with mDCs isolated from non-infected inflamed liver mDCs from HCV-infected liver (a) demonstrated higher expression of MHC class II, CD86 and CD123, (b) were more efficient stimulators of allogeneic T-cells and (c) secreted less IL-10. Reduced IL-10 secretion may be a factor in the enhanced functional properties of mDCs from HCV infected liver because antibody depletion of IL-10 enhanced the ability of mDCs from non-infected liver to stimulate T-cells. In contrast, pDCs were present at lower frequencies in HCV-infected liver and expressed higher levels of the regulatory receptor BDCA-2.

CONCLUSIONS

In HCV-infected liver the combination of enhanced mDC function and a reduced number of pDCs may contribute to viral persistence in the face of persistent inflammation.

The effects of gene gun delivered pIL-3 adjuvant on skin pathology and cytokine expression

The aim of this study was to investigate skin immunopathology following gene gun delivery of plasmid-encoding interleukin 3 (pIL-3) and hence explore the possible mechanisms of its adjuvant activity. Using the sheep as the experimental model, expressible pIL-3 was administered to the epidermis and the dermal/epidermal junction and its effects on the skin were assessed by histopathology, immunohistology and quantitative RT-PCR for a range of pro-inflammatory and immune response polarizing cytokines. Delivery of both functional and non-functional plasmids caused an acute inflammatory response with the infiltration of neutrophils and micro-abscess formation; however, the response to pIL-3 was more severe and was also associated with an early (24 h) infiltration of B cells and a later accumulation of CD172a-/CD45RA+ dendritic cells (DC). In terms of cytokine transcript expression, an early TNFalpha response was stimulated by gene gun delivery of plasmid-associated gold beads, which coincided with an immediate infiltration of neutrophils. However, only pIL-3 triggered the short-lived expression of IL-3 (peaking at 6 h) and significant long-term increases in both TNFalpha and IL-1beta. pIL-3 did not affect the expression of the immune response polarizing cytokines, IL-10 and IL-12.

The effect of gene gun-delivered pGM-CSF on the immunopathology of the vaccinated skin

The aim of this study was to investigate the skin immunopathology of gene gun-delivered plasmid-encoded granulocyte-macrophage colony-stimulating factor (pGM-CSF) and hence explore the possible mechanisms of its adjuvant activity. Using sheep as the experimental model, expressible pGM-CSF was administered to the epidermis and the dermal/epidermal junction and its effects on the skin were assessed by histopathology, immunohistology and quantitative RT-PCR for a range of pro-inflammatory and immune response-polarizing cytokines. Both functional and non-functional plasmids caused an acute inflammatory response with the infiltration of neutrophils and micro-abscess formation; however, the response to pGM-CSF was more severe and was also associated with the accumulation of eosinophils, immature (CD1b(-)/CD172a(-)) dendritic cells and B cells. In terms of cytokine expression, an early TNF-alpha response was stimulated by gene gun delivery of plasmid-associated gold beads, which coincided with an immediate infiltration of neutrophils. However, only pGM-CSF triggered the short-lived expression of GM-CSF (peaking at 4 h) and significant long-term increases in both TNF-alpha and IL-1beta. pGM-CSF did not affect the expression of the immune response-polarizing cytokines, IL-10 and IL-12.

IL-4 suppresses UVB-induced apoptosis in skin

In this study, cutaneous role of IL-4 in UVB-induced apoptosis was investigated using transgenic mice with skin-specific expression of IL-4 (IL-4 Tg mice). The transgenic mice did not show any gross clinical abnormalities. However, epidermis was thickened and increased MHC class II positive cells were detected as well as enhanced expression of inflammatory cytokines such as IL-1 and TNF-alpha in skin. In addition, histological analysis revealed increased infiltration of lymphocytes, acanthosis, hyperkeratosis, and parakeratosis in skin of IL-4 Tg mice. The physiological effect of IL-4 overexpression in skin against environmental stimulus such as UVB was investigated by irradiating wild-type and IL-4 Tg mice with UVB followed by evaluation of apoptosis. The result demonstrated suppressed apoptosis in epidermis of IL-4 Tg mice compared with wild-type mice. To further assess anti-apoptotic function of IL-4 in keratinocytes, stable cell clones were made where IL-4 was constitutively overexpressed and examined for UVB-induced apoptosis. The results showed that apoptosis was remarkably decreased in IL-4 over-expressing cell clones compared with that in mock transfected cells. Collectively, data presented here shows that IL-4 has an inhibitory effect against UVB-induced apoptosis in keratinocytes, suggesting that IL-4 may be an important regulator in cutaneous immunity against UVB.

Macrophage-colony stimulating factor enhances MHC-restricted presentation of exogenous antigen in dendritic cells

Previous studies have shown that dendritic cells (DCs) can phagocytize, process and present a microencapsulated form of ovalbumin (OVA) in the context of class I MHC as well as class II MHC. In the present study, we examined the effects of recombinant human macrophage-colony stimulating factor (M-CSF) on the MHC-restricted presentation of microencapsulated OVA by DCs. Two types of DCs were generated from mouse bone marrow (BM) cells, one type with granulocyte/macrophage-colony stimulating factor (GM-CSF) alone, the other type with GM-CSF and interleukin (IL)-4. Pretreatment with M-CSF significantly enhanced both class I MHC and class II MHC-restricted presentation of exogenous OVA by both types of DCs. The enhancing activity of M-CSF on antigen presentation was more potent in DCs generated with GM-CSF alone compared to DCs generated with both GM-CSF and IL-4. Pretreatment of the DCs with M-CSF did not increase phagocytic activity or total level of expression of class I MHC (H-2K(b)) molecules, but increased expression of OVA peptide-H-2K(b) complexes upon phagocytosis of microencapsulated OVA. These results demonstrate that M-CSF increases intracellular processing events of phagocytized antigen in DCs.