Differentiation of immunostimulatory stem-cell- and monocyte-derived dendritic cells involves maturation of intracellular compartments responsible for antigen presentation and secretion

Immune Cell Alterations and PI3K-PKB Pathway Suppression in Patients with Allergic Rhinitis Undergoing Sublingual Immunotherapy

INTRODUCTION

Our prior clinical study assessed the efficacy and safety of sublingual immunotherapy (SLIT) with standardized Dermatophagoides farina drops on patients with allergic rhinitis (AR) while analyzing the characteristics of adverse reactions. This study was conducted to evaluate the immune cell composition alterations in AR patients before and after SLIT, and to comprehensively investigate the role and changes of antigen-specific immune cells associated with treatment efficacy.

METHODS

A total of 68 AR patients who completed 12 months of SLIT were included in the study. Before the trial's initiation and after 1 year of SLIT, 10 ml of venous blood was collected. Peripheral blood mononuclear cells were isolated using the Ficoll gradient method. The mRNA transcriptome was analyzed using an Affymetrix microarray. The proportions of 22 immune cell types were calculated via the CIBERSORTx platform. Correlations between each immune cell type and SLIT were analyzed. PI3K-PKB pathway dysregulation were analyzed using quantitative PCR and Western blot. Flow cytometry was utilized to assess the percentages of Th1 and Th2 cells.

RESULTS

Mono-sensitized AR patients exhibited marked increases in plasma cells, activated memory T cells, regulatory T cells, and activated dendritic cells, while experiencing decreased neutrophils and resting dendritic cells. In poly-sensitized AR patients, the most notable change was an increase in regulatory T cells, coupled with decreased T follicular helper cells, resting dendritic cells, and activated mast cells. These findings indicated that SLIT reshaped immune cell profiles in AR patients, and, notably, the specific changes differed between mono-sensitized and poly-sensitized individuals. Furthermore, SLIT appeared to shift the immune response towards a Th2 decrease profile in both groups. Importantly, suppression of the PI3K-PKB pathway was evidenced as inhibition of PKB phosphorylation and the decrease of glycogen synthase kinase 3 β (GSKβ) and mammalian target of rapamycin (mTOR) expression after SLIT.

CONCLUSION

Our study has demonstrated that SLIT treatment led to distinct changes in immune cell profiles between mono-sensitized and poly-sensitized AR patients. Furthermore, SLIT appeared to reduce a Th2 immune response, highlighting its efficacy in AR treatment. Importantly, the study revealed the suppression of the PI3K-PKB pathway, shedding light on the immunological mechanisms underlying SLIT's effectiveness.

Immune Responses Induced at One Hour Post Cataract Surgery Wounding of the Chick Lens

While the lens is an avascular tissue with an immune-privileged status, studies have now revealed that there are immune responses specifically linked to the lens. The response to lens injury, such as following cataract surgery, has been shown to involve the activation of the resident immune cell population of the lens and the induction of immunomodulatory factors by the wounded epithelium. However, there has been limited investigation into the immediate response of the lens to wounding, particularly those induced factors that are intrinsic to the lens and its associated resident immune cells. Using an established chick embryo ex vivo cataract surgery model has made it possible to determine the early immune responses of this tissue to injury, including its resident immune cells, through a transcriptome analysis. RNA-seq studies were performed to determine the gene expression profile at 1 h post wounding compared to time 0. The results provided evidence that, as occurs in other tissues, the resident immune cells of the lens rapidly acquired a molecular signature consistent with their activation. These studies also identified the expression of many inflammatory factors by the injured lens that are associated with both the induction and regulation of the immune response.

Propolis modulates miRNAs involved in TLR-4 pathway, NF-κB activation, cytokine production and in the bactericidal activity of human dendritic cells

Objectives

Dendritic cells (DCs) are antigen-presenting cells, essential for recognition and presentation of pathogens to T cells. Propolis, a resinous material produced by bees from various plants, exhibits numerous biological properties, highlighting its immunomodulatory action. Here, we assayed the effects of propolis on the maturation and function of human DCs.

Methods

DCs were generated from human monocytes and incubated with propolis and LPS. NF-κB and cytokines production were determined by ELISA. microRNA's expression was analysed by RT-qPCR and cell markers detection by flow cytometry. Colony-forming units were obtained to assess the bactericidal activity of propolis-treated DCs.

Key findings

Propolis activated DCs in the presence of LPS, inducing NF-kB, TNF-α, IL-6 and IL-10 production. The inhibition of hsa-miR-148a and hsa-miR-148b abolished the inhibitory effects on HLA-DR and pro-inflammatory cytokines. The increased expression of hsa-miR-155 may be correlated to the increase in TLR-4 and CD86 expression, maintaining LPS-induced expression of HLA-DR and CD40. Such parameters may be involved in the increased bactericidal activity of DCs against Streptococcus mutans.

Conclusion

Propolis modulated the maturation and function of DCs and may be useful in the initial steps of the immune response, providing a novel approach to the development of DC-based strategies and for the discovery of new immunomodulators.

Intravenous immunoglobulin modulates the maturation of TLR 4-primed peripheral blood monocytes

Intravenous immunoglobulin (IgIV) has immune modulating effects on the differentiation and function of dendritic cells (DC). Peripheral blood CD14+ monocytes were induced to differentiate into immature DC with IL-4/GM-CSF. DC maturation was analyzed by flow cytometry, and function assessed for antigen uptake and antigen processing. IgIV added during the differentiation process induced immature DC to differentiate into a mature DC with increased expression of CD83 and CCR7. A "priming" step with low concentrations of LPS or other TLR agonists that utilize the myD88 signaling pathway was necessary to observe these changes. These modulated DCs had reduced antigen uptake, but exhibited increased antigen presentation. Treatment of the IgIV with pepsin to generate F(ab')2 fragments abrogated these effects on DC maturation and function. The enhanced differentiation of PBM into DC required two signals: an initial exposure to low concentrations of LPS followed by IVIG. The second signal with IVIG was Fc dependent.

Dendritic cells with lymphocyte-stimulating activity differentiate from human CD133 positive precursors

CD133 is a hallmark of primitive myeloid progenitors. We have addressed whether human cord blood cells selected for CD133 can generate dendritic cells, and Langerhans cells in particular, in conditions that promote that generation from CD34(+) progenitors. Transforming growth factor-β1 (TGF-β1) and anti-TGF-β1 antibody, respectively, were added in some experiments. With TGF-β, monocytoid cells were recognized after 7 days. Immunophenotypically immature dendritic cells were present at day 14. After 4 more days, the cells expressed CD54, CD80, CD83, and CD86 and were potent stimulators in mixed lymphocyte reaction; part of the cells expressed CD1a and langerin, but not Birbeck granules. Without TGF-β, only a small fraction of cells acquired a dendritic shape and expressed the maturation-related antigens, and lymphocytes were poorly stimulated. With anti-TGF-β, the cell growth was greatly hampered, CD54 and langerin were never expressed, and lymphocytes were stimulated weakly. In conclusion, CD133(+) progenitors can give rise in vitro, through definite steps, to mature, immunostimulatory dendritic cells with molecular features of Langerhans cells, although without Birbeck granules. Addition of TGF-β1 helps to stimulate cell growth and promotes the acquisition of mature immunophenotypical and functional features. Neither langerin nor Birbeck granules proved indispensable for lymphocyte stimulation.

Targeted PLGA nano- but not microparticles specifically deliver antigen to human dendritic cells via DC-SIGN in vitro

Vaccine efficacy is strongly enhanced by antibody-mediated targeting of vaccine components to dendritic cells (DCs), which are professional antigen presenting cells. However, the options to link antigens or immune modulators to a single antibody are limited. Here, we engineered versatile nano- and micrometer-sized slow-release vaccine delivery vehicles that specifically target human DCs to overcome this limitation. The nano- (NPs) and microparticles (MPs), with diameters of approximately 200nm and 2microm, consist of a PLGA core coated with a polyethylene glycol-lipid layer carrying the humanized targeting antibody hD1, which does not interact with complement or Fc receptors and recognizes the human C-type lectin receptor DC-SIGN on DCs. We studied how these particles interact with human DCs and blood cells, as well as the kinetics of PLGA-encapsulated antigen degradation within DCs. Encapsulation of antigen resulted in almost 38% degradation for both NPs and MPs 6days after particle ingestion by DCs, compared to 94% when nonencapsulated, soluble antigen was used. In contrast to the MPs, which were taken up rather nonspecifically, the NPs effectively targeted human DCs. Consequently, targeted delivery only improved antigen presentation of NPs and induced antigen-dependent T cell responses at 10-100 fold lower concentrations than nontargeted NPs.

In vivo visualization of albumin degradation in the proximal tubule

Albuminuria is a key marker of renal injury and a major risk factor for cardiovascular disease. In vivo imaging techniques with fluorescent albumin have allowed visualization of its movement within the whole kidney but they could not distinguish between intact and degraded albumin. To visualize albumin degradation in proximal tubular cells in vivo we used an albumin conjugate (dye quenched (DQ)-albumin), which only fluoresces when it is degraded. In cultured proximal tubule cells, the fluorescent signal from DQ-albumin was dependent on endocytosis and lysosomal function and showed that at any time about 40% of endocytosed DQ-albumin was degraded. Significant accumulation of conventional Texas Red-labeled albumin and degraded DQ-albumin was found in rat proximal tubules 5 min after injection. Importantly, no hint of DQ-albumin was detected in the serum, suggesting that the fluorescent signal in the proximal tubules was derived from tubular degradation of intact albumin. Our study shows that DQ-albumin, together with conventional fluorescent conjugates of intact albumin, can be used to visualize albumin degradation by proximal tubules in vivo.

CTLA4-Ig-modified dendritic cells inhibit lymphocyte-mediated alloimmune responses and prolong the islet graft survival in mice

The induction of antigen specific tolerance is critical for prevention and treatment of allograft rejection. In this study, we transfected CTLA4-Ig gene into dendritic cells (DCs), and investigated their effect on inhibition of lymphocyte activity in vitro and induction of immune tolerance on pancreatic islet allograft in mice. An IDDM C57BL/6 murine model induced by streptozotocin is as model mouse. The model mice were transplanted of the islet cells isolated from the BALB/c mice to their kidney capsules, and injected of CTLA4-Ig modified DCs (mDCs). The results showed that mDCs could significantly inhibit T lymphocyte proliferation and induce its apoptosis; whereas, unmodified DCs (umDCs) promoted the murine lymphocyte proliferation. Compared with injection of umDCs and IgG1 modified DCs, the injection of mDCs prolonged IDDM mice's allograft survival, and normalized their plasma glucose (PG) levels within 3 days and maintained over 2 weeks. The level of IFN-gamma was lower and the level of IL-4 was higher in mDCs treated recipient mice than that in control mice, it indicated that mDCs led to Th1/Th2 deviation. After 7 days of islet transplantation, HE stain of the renal specimens showed that the islets and kidneys were intact in structure, and islet cells numbers are increased in mDCs treated mice. Our studies suggest that DCs expressing CTLA4-Ig fusion protein can induce the immune tolerance to islet graft and prolong the allograft survival through the inhibition of T cell proliferation in allogeneic mice.

Early activation of mucosal dendritic cells and macrophages in acute Campylobacter colitis and cholera: An in vivo study

BACKGROUND AND AIM

Macrophages and dendritic cells are closely related mononuclear phagocytic cells. Little is known about their in vivo role in acute intestinal bacterial infections in humans. We undertook to evaluate these cells in rectal mucosal biopsies of patients with acute colitis.

METHODS

All mucosal mononuclear phagocytic cells in rectal biopsies of patients with acute Campylobacter colitis (n = 5), shigellosis (n = 5), and cholera (n = 10) were evaluated ultrastructurally and compared with those in controls (n = 5).

RESULTS

Mononuclear phagocytic cells in the superficial rectal mucosa showed a higher prevalence of ultrastructural features of activation in Campylobacter colitis and cholera than in controls. A lower prevalence of features of activation with increased monocytes was seen in shigellosis. Cells with the ultrastructural morphology of activated dendritic cells constituted 41% and 45% of all mononuclear phagocytic cells in two of five patients with Campylobacter colitis and 4-22% of cells in four of 10 patients with cholera. Their presence in patients with Campylobacter colitis was associated with significant surface epithelial damage and prominent acute inflammatory changes in the mucosa.

CONCLUSIONS

This is the first ultrastructural study to show activated macrophages and dendritic cells in vivo in acute Campylobacter colitis and cholera. Dendritic cell activation occurred early in the clinical course of these infections. Surface epithelial damage may play a role in the activation of dendritic cells.

Characterisation of a dendritic cell subset in synovial tissue which strongly expresses Jak/STAT transcription factors from patients with rheumatoid arthritis

OBJECTIVES

To characterise the phenotype of the putative dendritic cells strongly expressing Jak3 and STAT4, which have been previously identified in the synovial tissue of patients with active rheumatoid arthritis (RA).

METHODS

Synovial biopsy specimens were obtained at arthroscopy from 30 patients with active RA (42 synovial biopsies). Immunohistological analysis was performed using monoclonal antibodies to detect dendritic cell subsets, including activation markers and cytokines relevant to dendritic cell function. Co-localisation of cell surface markers and cytokines was assessed primarily using sequential sections, with results confirmed by dual immunohistochemistry and immunofluorescence with confocal microscopy.

RESULTS

The dendritic cells identified in RA synovial tissue that strongly express Jak3 also strongly express STAT4 and STAT 6 and are correlated with the presence of serum rheumatoid factor. These cells are not confined to a single dendritic cell subset, with cells having phenotypes consistent with both myeloid- and plasmacytoid-type dendritic cells. The activation status of these dendritic cells suggests that they are maturing or mature dendritic cells. These dendritic cells produce IL12 as well as interferon alpha and gamma.

CONCLUSIONS

The close correlation of these dendritic cells with the presence of serum rheumatoid factor, a prognostic factor for worse disease outcome, and the strong expression by these cells of components of the Jak/STAT transcription factor pathway suggest a potential therapeutic target for the treatment of RA.

The Intradermal Leishmanin Reaction Induces Antigen-specific Maturation of Canine Dendritic Cells with Up-regulation of MHCII Synthesis and Expression

Dendritic cells (DCs) are professional antigen-presenting cells that reside in many tissues, including the skin. This study showed that intradermal injection of leishmanin in Leishmania infantum-infected dogs induced the "up-regulation" of surface MHCII expression, associated with progressive ultrastrucutural changes characteristic of DC maturation, including the formation of multilaminar MHC class II-containing compartments and arrays of tubulo-vesicular structures. These changes were not observed in control dogs from L. infantum non-endemic areas. The results indicated that canine DCs were effector cells in delayed-type hypersensitivity, that the leishmanin reaction was specific for a cell-mediated reaction to L. infantum in infected dogs, and that canine DCs possessed ultrastructural organelles reminiscent of those in activated human DCs.

Changes in the proteomic profile during differentiation and maturation of human monocyte-derived dendritic cells stimulated with granulocyte macrophage colony stimulating factor/interleukin-4 and lipopolysaccharide

Dendritic cells (DCs) are highly specialized antigen-presenting cells that play an essential role in the immune response. We used the proteomic approach based on two-dimensional gel electrophoresis and mass spectrometry to identify the protein changes that occur during differentiation of DCs from monocytes (Mo) stimulated with granulocyte macrophage colony stimulating factor/interleukin-4 (GM-CSF/IL-4) and during the maturation of immature DCs stimulated with lipopolysaccharide. Sixty-three differentially expressed proteins (+/- two-fold) were unambiguously identified with sequence coverage greater than 20%. They corresponded to only 36 different proteins, because 11 were present as 38 electrophoretic forms. Some proteins such as tropomyosin 4 and heat shock protein 71 presented differentially expressed electrophoretic forms, suggesting that many of the changes in protein expression that accompany differentiation and maturation of DCs occur in post-translationally modified proteins. The largest differences in expression were observed for actin (21-fold in Mo), Rho GDP-dissociation inhibitor 2 (20-fold in Mo), vimentin (eight-fold in immature DCs), lymphocyte-specific protein 1 (12-fold in mature DCs) and thioredoxin (14-fold in mature DCs). Several proteins are directly related to functional and morphological characteristics of DCs, such as cytoskeletal proteins (cytoskeleton rearrangement) and chaperones (antigen processing and presentation), but other proteins have not been assigned specific functions in DCs. Only a few proteins identified here were the same as those reported in proteomic studies of DCs, which used different stimuli to produce the cells (GM-CSF/IL-4 and tumor necrosis factor-alpha). These data suggest that the DC protein profile depends on the stimuli used for differentiation and especially for maturation.

Dendritic Cell Differentiation and Maturation in Embryonic Rat Liver: Immunohistochemistry and Electron Microscopy with Reference to Dendritic Cell Contacts

This study investigated the dendritic cell (DC) differentiation in embryonic rat liver utilizing in situ ultrastructural characterization and immunohistochemistry. The study revealed the existence of DCs early in hepatic ontogeny with positive immune staining to the OX-62 monoclonal antibody. DCs existed in three differentiating stages: immature, mature and transitional forms in between. At 14 and 16 days of gestation, immature and transitional forms of DCs dominated. Mature cells increased significantly in number through late gestational days (18 days onwards). DCs (particularly mature and moderate mature forms) revealed signs of active phagocytosis manifested by the existence of cytoplasmic phagosomes and heterophagosomes. At 18 days of gestation as well as newborn liver mature DCs displayed two distinct morphological phenotypes according to the degree of development of either the smooth endoplasmic reticulum or the lysosomal compartment. Mature DCs delineated close appositions to other DCs, hepatocytes, and clustering with lymphocytes especially through their cellular processes. The features of phagocytosis and DC-T-cell contacts may signify a role of DCs in immune surveillance in the embryonic liver.

In Vitro Generation of Functional Dendritic Cells from Human Umbilical Cord Blood CD34 + Cells by a 2-Step Culture Method

Dendritic cells (DCs) are the most potent antigen-presenting cells in terms of initiating primary T-cell-dependent immune responses. We devised a 2-step culture method for obtaining sufficient numbers of functional DCs from umbilical cord blood (CB) CD34+ cells. In the first step, CB CD34+ cells were expanded by stimulation with early-acting cytokines such as stem cell factor (SCF), flt3 ligand (FL), and thrombopoietin (TPO) to amplify the hematopoietic progenitor cells. In the second step, granulocyte-macrophage colony-stimulating factor and interleukin 4 were added, and incubation was continued for another 5 days to induce differentiation of the expanded cells into DCs. During the first step of culturing with TPO, SCF, and FL, the total numbers of nucleated cells gradually increased, peaking at 4 weeks (245.3-fold). During the second step, expression of CD1a, CD83, and CD86 increased. Electron microscopic findings showed that these cells had cytosolic expansion to form dendrites and major histocompatibility complex class II compartments, which are characteristic of DCs. Functional analyses revealed that these cells had phagocytic activity and were capable of stimulating allogeneic T-cells in vitro.

Histamine downregulates CD14 expression via H2 receptors on human monocytes

Lipopolysaccharide (LPS) binds to LPS-binding protein (LBP) in plasma and is delivered to the cell surface receptor CD14 on human monocyte. LPS is transferred to the transmembrane signaling receptor toll-like receptor (TLR) 4. In the present study, the effect of histamine on the expression of CD14 on human monocytes was investigated. Histamine concentration- and time-dependently decreased the expression of cell surface CD14, whereas histamine did not decrease mRNA for CD14 nor increase soluble CD14 (sCD14). The inhibitory effects of histamine on CD14 expression were antagonized by H2-receptor antagonist, but not by H1 and H3/H4 antagonist. The effects of selective H2-receptor agonists, 4-methylhistamine and dimaprit, on CD14 expression mimicked that of histamine indicating that histamine regulated CD14 expression through the stimulation of H2-receptors. The pretreatment with histamine partially inhibited the LPS-induced TNF-alpha production in human peripheral blood mononuclear cells (PBMC). Such inhibition might be due to the down-regulation of CD14 expression on monocytes by histamine.

Umbilical cord blood dendritic cells are a rich source of soluble HLA-DR: synergistic effect of exosomes and dendritic cells on autologous or allogeneic T-Cell proliferation

In this study, we compared soluble HLA-DR (sHLA-DR) production in the culture supernatants of various cell sources [T and B cells, monocytes and dendritic cells (DCs) either from adult peripheral blood (PB) or umbilical cord blood (UCB)]. DCs produced the highest amount of sHLA-DR molecules as compared to other cell sources, with UCB DCs producing the highest amount. Different kinetics of sHLA-DR production were found between immature and mature UCB DCs (mDC, iDC) (derived either from CD34(+) or CD14(+) cells). Maximum production of sHLA-DR was observed in 72-hour culture supernatants of both CD34- and CD14-derived mDCs, whereas it peaked in the 24-hour culture supernatants from iDC. sHLA-DR molecules were pelleted after sequential centrifugation from UCB CD34(+) DCs and were found to contain both 36 kD alpha-chain and 29 kD beta-chain of HLA-DR, CD86, and Fas molecules. These sHLA-DR containing vesicles/exosomes alone evoked weak proliferative responses from autologous and allogeneic T cells, but the immune response was significantly increased when vesicles/exosomes were presented with DCs.