Histamine Induces the Generation of Monocyte-Derived Dendritic Cells that Express CD14 but not CD1a
2005; Elsevier BV; Volume: 125; Issue: 4 Linguagem: Inglês
10.1111/j.0022-202x.2005.23891.x
ISSN1523-1747
AutoresNorito Katoh, Fujiko Soga, Takeshi Nara, Koji Masuda, Saburo Kishimoto,
Tópico(s)Antimicrobial Peptides and Activities
ResumoThe local cytokine environment and the presence of stimulatory signals determine whether monocytes acquire dendritic cell or macrophage characteristics and functions. In this study, we examined the effect of histamine, a prototypic mediator of allergic inflammation, on the granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4-driven differentiation of monocytes into monocyte-derived dendritic cells (MoDC), which typically showed CD1a+CD14- phenotype. Monocytes from healthy adult donors were cultured with GM-CSF and IL-4 in the presence or absence of histamine, and the phenotypes and function of these cells were analyzed. Histamine induced the generation of CD1a-CD14+ cells, which exhibited cytological and phenotypical characteristics of dendritic cells (DC), showed enhanced phagocytic activity and cytokine-producing capacity, but demonstrated weak allo-stimulatory capacity compared with CD1a+CD14- MoDC. The inhibitory effects of histamine on CD1a+CD14- MoDC differentiation were antagonized by cimetidine, an H2 receptor antagonist, but not by H1 and H3 receptor blockers, and were mimicked by an H2 receptor agonist. Culture supernatant of histamine-treated monocytes also inhibited CD1a+CD14- MoDC differentiation, which was restored by the removal of IL-10. These results suggest that histamine-driven CD1a-CD14+ DC amplify their antigen-independent inflammatory reaction and may contribute to the exacerbation of allergic diseases. The local cytokine environment and the presence of stimulatory signals determine whether monocytes acquire dendritic cell or macrophage characteristics and functions. In this study, we examined the effect of histamine, a prototypic mediator of allergic inflammation, on the granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4-driven differentiation of monocytes into monocyte-derived dendritic cells (MoDC), which typically showed CD1a+CD14- phenotype. Monocytes from healthy adult donors were cultured with GM-CSF and IL-4 in the presence or absence of histamine, and the phenotypes and function of these cells were analyzed. Histamine induced the generation of CD1a-CD14+ cells, which exhibited cytological and phenotypical characteristics of dendritic cells (DC), showed enhanced phagocytic activity and cytokine-producing capacity, but demonstrated weak allo-stimulatory capacity compared with CD1a+CD14- MoDC. The inhibitory effects of histamine on CD1a+CD14- MoDC differentiation were antagonized by cimetidine, an H2 receptor antagonist, but not by H1 and H3 receptor blockers, and were mimicked by an H2 receptor agonist. Culture supernatant of histamine-treated monocytes also inhibited CD1a+CD14- MoDC differentiation, which was restored by the removal of IL-10. These results suggest that histamine-driven CD1a-CD14+ DC amplify their antigen-independent inflammatory reaction and may contribute to the exacerbation of allergic diseases. atopic dermatitis dendritic cells dermal dendritic cells fluorescein isothiocyanate granulocyte-macrophage colony-stimulating factor histamine receptor interferon-γ interleukin Langerhans cells lipopolysaccharide monoclonal antibody macrophage colony-stimulating factor mean fluorescence intensity monocyte-derived dendritic cells relative fluorescence intensity A lack of appropriate exogenous stimuli induces monocytes to undergo apoptosis, whereas under the influence of distinct signals such as proinflammatory cytokines, these cells differentiate into macrophages or dendritic cells (DC) (Katoh et al., 2000Katoh N. Kraft S. Weßendorf J.H.M. Bieber T. The high-affinity IgE receptor (FcεRI) blocks apoptosis in normal human monocytes.J Clin Invest. 2000; 105: 183-190Google Scholar; Lanzavecchia and Sallusto, 2001Lanzavecchia A. Sallusto F. The instructive role of dendritic cells on T cell responses: Lineages, plasticity and kinetics.Curr Opin Immunol. 2001; 13: 291-298Google Scholar). Macrophages can perform phagocytosis and produce proinflammatory or anti-inflammatory cytokines that regulate inflammatory reactions (Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar). In contrast, DC display the capacity to initiate primary and secondary T cell responses and the most efficient professional antigen-presenting cells (Lanzavecchia and Sallusto, 2001Lanzavecchia A. Sallusto F. The instructive role of dendritic cells on T cell responses: Lineages, plasticity and kinetics.Curr Opin Immunol. 2001; 13: 291-298Google Scholar). DC comprise heterogeneous populations with different morphologies and molecules expressed as a function of their maturation stage (Grassi et al., 1998Grassi F. Dezutter-Dambuyant C. Mcllroy D. et al.Monocyte-derived dendritic cells have a phenotype comparable to that of dermal dendritic cells and display ultrastructural granules distinct from Birbeck granules.J Leukoc Biol. 1998; 64: 484-493Google Scholar). Dermal DC (DDC) migrated from skin explants are divided into three subsets by phenotypic criteria: CD1a-CD14-, CD1a+CD14-, and CD1a-CD14+ (Nestle et al., 1993Nestle F.O. Zheng X.G. Thompson C.B. Turka L.A. Nickoloff B.J. Characterization of dermal dendritic cells obtained from normal human skin reveals phenotypic and functionally distinctive subsets.J Immunol. 1993; 151: 6535-6545Google Scholar; Larregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar). CD1a-CD14+ subset of DDC show decreased capacity to stimulate resting T cells when compared with the other two subsets. These fundamental functional divergences may be of importance for the putative regulatory role of monocyte-derived DC (MoDC) or macrophages in tissues, and consequently for the outcome of local inflammatory responses (Novak et al., 1999Novak N. Haberstok J. Geiger E. Bieber T. Dendritic cells in allergy.Allergy. 1999; 54: 792-803Google Scholar). Thus far, several factors such as corticosteroids, interleukin (IL)-10, and signaling evoked by the engagement of FcεRI are known to influence monocyte differentiation into DC (Buelens et al., 1997Buelens C. Verhasselt V. de Grote D. Thielemans K. Goldman M. Willems F. Interleukin-10 prevents the generation of dendritic cells from human peripheral blood mononuclear cells cultured with interleukin-4 and granulocyte/macrophage colony-stimulating factor.Eur J Immunol. 1997; 27: 756-762Google Scholar; Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar; Woltman et al., 2002Woltman A.M. Massacrier C. de Fijter J.W. Caux C. van Kooten C. Corticosteroids prevent generation of CD34+-derived dermal dendritic cells but do not inhibit Langerhans cell development.J Immunol. 2002; 168: 6181-6188Google Scholar). Histamine is an important mediator involved in various physiological and pathological conditions including immediate hypersensitivity reaction and inflammation (Leurs et al., 1995Leurs R. Smit M.J. Timmerman H. Molecular pharmacological aspects of histamine receptors.Pharmacol Ther. 1995; 66: 413-463Google Scholar). Recently, new immunomodulatory functions of histamine were discovered (Jutel et al., 2002Jutel M. Watanabe T. Akdis M. Blaser K. Akdis C.A. Immune regulation by histamine.Curr Opin Immunol. 2002; 14: 735-740Google Scholar) (i) histamine augments antigen-receptor-mediated T and B cell proliferation (Banu and Watanabe, 1999Banu Y. Watanabe T. Augmentation of antigen receptor-mediated responses by histamine H1 receptor signaling.J Exp Med. 1999; 189: 673-682Google Scholar), (ii) enhances Th1-type responses by triggering H1 receptor (H1R), whereas Th1- and Th2-type responses are negatively regulated by H2R (Jutel et al., 2001Jutel M. Watanabe T. Klunker S. et al.Histamine regulates T-cell and antibody responses by differential expression of H1 and H2 receptors.Nature. 2001; 413: 420-425Google Scholar), and (iii) alters the repertoire of cytokines and chemokines secreted by mature DC that induces the polarization of naïve CD4+ T cells toward Th2 phenotypes (Caron et al., 2001Caron G. Delneste Y. Roelandts E. Duez C. Bonnefoy J.Y. Pestel J. Jeannin P. Histamine polarizes human dendritic cells into Th2 cell-promoting effector cells.J Immunol. 2001; 167: 3682-3686Google Scholar; Mazzoni et al., 2001Mazzoni A. Young H.A. Spitzer J.H. Visintin A. Segal D.M. Histamine regulates cytokine production in maturing dendritic cells, resulting in altered T cell polarization.J Clin Invest. 2001; 108: 1865-1873Google Scholar). Therefore, histamine may contribute to other mechanisms involved in the outcome of DC differentiation. In this report, we examined the effect of histamine on the granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4-driven differentiation of monocytes into MoDC. In monocytes from non-atopic healthy individuals we found that (1) histamine prevents the generation of CD1a+CD14- DC and induces CD1a-CD14+ DC, which share some phenotypic and functional features with previously described CD1a-CD14+ DDC (Nestle et al., 1993Nestle F.O. Zheng X.G. Thompson C.B. Turka L.A. Nickoloff B.J. Characterization of dermal dendritic cells obtained from normal human skin reveals phenotypic and functionally distinctive subsets.J Immunol. 1993; 151: 6535-6545Google Scholar; Larregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar); (2) the effect is mediated by H2R; and (3) it results from the histamine-induced secretion of IL-10. At the start of culturing, the cells used to generate MoDC in a typical experiment consisted of 95% monocytes, as indicated by CD14 expression and a typical light-scattering profile. They were induced to differentiate into MoDC with IL-4 and GM-CSF over a period of 6 d. Under control conditions with GM-CSF and IL-4, the cells rapidly became non-adhered to culture plate and formed large clusters. Histamine-treated cells were also non-adhered and formed clusters. Both of them were irregularly shaped and showed extended veils (Figure 1a). The dendritic morphology with small dendrites was also observed in both of them. In contrast, macrophage colony-stimulating factor (M-CSF)-induced macrophages were adherent, roundly shaped cells containing numerous vacuoles. Despite homogeneous cytological appearance, the expression of CD1a and CD14 by DC significantly changed when histamine was added at the start of culturing (Figure 1b). MoDC generated with GM-CSF and IL-4 expressed high levels of CD1a and low levels of CD14. In contrast, those generated in the presence of histamine expressed significantly lower levels of CD1a and higher levels of CD14. This inhibitory effect was significant at 100 nM, and highest at 100 μM, the highest concentration tested (Figure 1c). Histamine at 10 μM was used in the following experiment because it is within the concentration range of histamine detected in nasal secretions and brochoalveolar lavages from allergic patients after allergen challenge (Wenzel et al., 1988Wenzel S.E. Fowler A.A. Schwarz L.B. Activation of pulmonary mast cells by bronchoalveolar allergen challenge. In vivo release of histamine and tryptase in atopic subjects with and without asthma.Am Rev Respir Dis. 1988; 137: 1002-1008Google Scholar; Liu et al., 1990Liu M.C. Bleecker E.R. Lichtenstein L.M. et al.Evidence for elevated levels of histamine, prostaglandin D2, and other bronchoconstricting prostaglandins in the airways of subjects with mild asthma.Am Rev Respir Dis. 1990; 142: 126-132Google Scholar; Baroody et al., 1999Baroody F.M. Ford S. Proud D. Kagey-Sobotka A. Lichtenstein L. Naclerio R.M. Relationship between histamine and physiological changes during the early response to nasal antigen provocation.J Appl Physiol. 1999; 86: 659-668Google Scholar). The addition of histamine after 48 h, when most DC already expressed CD1a, still resulted in a significant decrease in CD1a surface expression. This downregulatory effect, however, was not observed when histamine was added on day 3 or later (data not shown). Histamine significantly inhibited the generation of CD1a+ mature MoDC when 100 ng per mL of lipopolysaccharide (LPS) was added on day 6 in addition to IL-4 and GM-CSF (Figure 1d and Figure 2b). We further examined whether histamine has any effect on the DC phenotype at day 6 (Figure 2a). Histamine induced a significant increase in MHC class II molecules, mannose receptor, CD11b, and CD68. On the other hand, the expressions of CD40 and CD80 were downregulated. No significant change was observed in CD86, CD83, CD1b, M-CSF receptor, and FXIIIa expression. LPS-matured histamine-treated DC demonstrated similar phenotypes with control-matured MoDC including CD83, except CD1a and CD14 (Figure 2b). The viability of the cells observed when comparing the histamine-treated and untreated group using trypan blue dye exclusion was not significantly different, suggesting that the inhibitory effect of histamine on DC differentiation was not because of the induction of cell death (data not shown). A characteristic feature of DC is their capacity to stimulate naïve T cells, as seen in the model of allogeneic mixed lymphocyte reaction (MLR). To determine the functional characteristics of cells generated in the presence of histamine, we examined whether histamine affects their T cell-stimulating capacity in MLR. As shown in Figure 3, compared with MoDC generated under control conditions, histamine-treated DC exhibited significantly reduced stimulatory activity toward allogeneic T cells. As shown in Figure 3c, CD4+ naïve T lymphocytes after incubation with allogeneic histamine-treated DC exhibited slightly but significantly higher intracellular expression of IL-4 than those stimulated with control DC (8.0%±4.2% vs 4.8%±3.0%, p=0.035, n=5). The intracellular expression of interferon-γ (IFN-γ) was not significantly different between them (histamine treated vs nil: 9.6%±5.4% vs 8.0%±3.0%, p=0.47, n=5). DC generated in the presence of histamine still induced a population of Th1 cells as determined by a higher number of IFN-γ-producing cells when compared with IL-4 (Th2 cells). Next, we examined their capacity to produce cytokines and chemokines by stimulating them with 100 ng per mL of LPS after 6 d of culturing. As reported previously (Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar), GM-CSF-IL-4-induced MoDC produced less proinflammatory cytokines and chemokines after stimulation with LPS compared with M-CSF-induced macrophages (Figure 4a,b). The ability to produce proinflammatory cytokines and chemokines including IL-10, however, was significantly elevated in histamine-treated CD1a-CD14+ cells except IL-12, which was confirmed by single-cell analysis (Figure 4c). Endogenous production of M-CSF was not detected in control MoDC and histamine-treated DC by using ELISA (data not shown). To investigate further as to whether histamine influences their function, the phagocytic activity of these cells was evaluated using fluorescein isothiocyanate (FITC)-labeled latex beads. Although control MoDC displayed low phagocytic activity on day 6 as reported elsewhere (Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar), histamine-treated DC exhibited high phagocytic activity compared with untreated MoDC (relative fluorescence intensity (rFI): 20.5±3.8 and 4.5±1.0, respectively, p=0.0139, n=6) (Figure 5). To elucidate the involvement of histamine receptor subtypes in the inhibition of DC differentiation, experiments using receptor subtype-selective antagonists were performed. Histamine-induced inhibition of CD1a expression and antigen-presenting capacity were completely blocked by preincubation of the monocytes with cimetidine but not with the H1R or H3R antagonists (Figure 6). In addition, the H2R agonist inhibited CD1a+ DC generation from monocytes. Histamine induces the release of several cytokines from monocytes. To examine whether the inhibitory effect of histamine on DC differentiation is mediated by endogenously synthesized cytokines, MoDC were generated with IL-4 and GM-CSF in the culture supernatant of monocytes cultured for 24 h in the presence or absence of histamine. As shown in Figure 7, the supernatant of monocyte treated with histamine showed a significant inhibitory effect on CD1a+CD14- DC generation. The removal of IL-10 with neutralizing monoclonal antibody (mAb) resulted in the restoration of CD1a+ DC differentiation inhibited by histamine as seen in the phenotype and allogeneic MLR. Endogenous production of IL-10 was 16±6 pg per mL in day 5 MoDC and 184±32 pg per mL in histamine-treated DC (Figure 4d). Pretreatment of the supernatant with anti-IL-1β, -IL-6, and -IL-12 mAb did not induce any change in the phenotype and function of DC. The removal of TNF-α from the supernatant reduced CD1a expression, suggesting its enhancing role in CD1a+ DC differentiation. DC comprise heterogeneous populations with different morphologies and molecules expressed as a function of their maturation stage. In the cutaneous tissue, Langerhans cell (LC) is a unique DC that strongly expresses CD1a. DDC also express varying levels of CD1a, even though CD1a expression on DDC was consistently weaker than on LC. In addition, LC lacks the monocyte–macrophage marker CD14 and representative DDC marker FXIIIa (Larregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar), whereas several subpopulations of DDC can be distinguished according to their differential expression of CD1a, CD14, and FXIIIa. DDC migrated from skin explants have been subdivided into three groups: CD1a+CD14-, CD1a-CD14-, and CD1a-CD14+ (Nestle et al., 1993Nestle F.O. Zheng X.G. Thompson C.B. Turka L.A. Nickoloff B.J. Characterization of dermal dendritic cells obtained from normal human skin reveals phenotypic and functionally distinctive subsets.J Immunol. 1993; 151: 6535-6545Google Scholar; Larregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar). According to their reports, CD1a-CD14+ DDC showed increased phagocytic activity and weak T cell-stimulatory potential. CD14+CD1a- DDC described byNestle et al., 1993Nestle F.O. Zheng X.G. Thompson C.B. Turka L.A. Nickoloff B.J. Characterization of dermal dendritic cells obtained from normal human skin reveals phenotypic and functionally distinctive subsets.J Immunol. 1993; 151: 6535-6545Google Scholar, however, are positive for intracellular FXIIIa, whereas those reported byLarregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar are negative for FXIIIa. This study showed that histamine prevents the IL-4/GM-CSF-driven differentiation of monocytes into CD1a+CD14- DC, but induced their differentiation into CD1a-CD14+FXIIIa+ cells, which exhibited increased phagocytic activity and weak allo-stimulatory capacity. It is thus suggested that the cells generated in the presence of histamine in this study are similar to DDC described byNestle et al., 1993Nestle F.O. Zheng X.G. Thompson C.B. Turka L.A. Nickoloff B.J. Characterization of dermal dendritic cells obtained from normal human skin reveals phenotypic and functionally distinctive subsets.J Immunol. 1993; 151: 6535-6545Google Scholar. In this study, histamine-induced DC were stained positively for intracellular FXIIIa and CD68. Both the molecules have been reported to be expressed in DDC, MoDC, and macrophages, but not or only weakly on LC (Caux et al., 1996Caux C. Vanbervliet B. Massacrier C. et al.CD34+ hematopoietic progenitors from human cord blood differentiate along two independent dendritic cell pathways in response to GM-CSF+TNFα.J Exp Med. 1996; 184: 695-706Google Scholar; Guironne et al., 2001Guironne G. Dezutter-Dambuyant C. Gaudillère A. Marèchal S. Schmitt D. Pèguet-Navarro J. Phenotypic and functional outcome of human monocytes or monocytes-derived dendritic cells in a dermal equivalent.J Invest Dermatol. 2001; 116: 933-939Google Scholar; Vakilla et al., 2005Vakilla J. Lotze M.T. Riga C. Jaffe R. A basis for distinguishing cultured dendritic cells and macrophages in cytospins and fixed sections.Pediatr Dev Pathol. 2005; 8: 43-51Google Scholar). Increased expression of molecules involved in Ag capture (mannose receptor, CD11b) and decreased expression of costimulatory molecules (CD80, CD40) in histamine-treated DC may correlate with their impaired antigen-presenting function to T lymphocytes and a higher endocytic activity. These phenotypic and functional features suggest that histamine-induced DC are in a transitional state of differentiation either toward CD1a+CD14- DDC or macrophages, but not LC.Larregina et al., 2001Larregina A.T. Morelli A.E. Spencer L.A. Logar A.J. Watkins S.C. Thomson A.W. Falo Jr, L.D. Dermal-resident CD14+ cells differentiate into Langerhans cells.Nat Immunol. 2001; 2: 1151-1158Google Scholar demonstrated that CD1a-CD14+FXIIIa- DDC differentiated into LC when cultured with TGF-β1 alone and that their allostimulatory capacity was enhanced when they were cultured with IL-4, GM-CSF, and TGF-β1. It is interesting to examine whether histamine-induced DC have the potential to differentiate into LC when cultured with TGF-β1 in addition to GM-CSF and IL-4. The fact that dust mite inhalation aggravates eruptions in atopic dermatitis (AD) patients suggests that DDC play a role in the pathogenesis of AD (Tupker et al., 1996Tupker R.A. De Monchy J.G. Coenraads P.J. Homan A. van der Meer J.B. Induction of atopic dermatitis by inhalation of house dust mite.J Allergy Clin Immunol. 1996; 97: 1064-1070Google Scholar). As mast cells are present in the dermis and epidermis in the AD skin lesions (Imayama et al., 1995Imayama S. Shibata Y. Hori Y. Epidermal mast cells in atopic dermatitis.Lancet. 1995; 346: 1559Google Scholar), the aggregation of FcεRI induced by environmental allergens (e.g., dust mites and pollen) and subsequent degranulation of mast cells often occur. In addition, IgE autoantibodies are frequently detected in the circulation of severe AD patients (Valenta et al., 2000Valenta R. Seiberler S. Natter S. Mahler V. Mossabeb R. Ring J. Stingl G. Autoallerg: A pathogenetic factor in atopic dermatitis?.J Allergy Clin Immunol. 2000; 105: 432-437Google Scholar), suggesting that the degranulation of peripheral blood basophils also occurs. In AD individuals, monocytes could therefore be exposed to histamine in the skin or peripheral circulation. In this study, histamine prevented the generation of CD1a+ DC from monocytes via H2R. In addition, this inhibitory effect was mediated by IL-10 produced endogenously by monocytes. This observation is in line with previous reports that showed that (i) the addition of IL-10 at the start of culturing with GM-CSF and IL-4 inhibits CD1a+ MoDC generation (Buelens et al., 1997Buelens C. Verhasselt V. de Grote D. Thielemans K. Goldman M. Willems F. Interleukin-10 prevents the generation of dendritic cells from human peripheral blood mononuclear cells cultured with interleukin-4 and granulocyte/macrophage colony-stimulating factor.Eur J Immunol. 1997; 27: 756-762Google Scholar; Allavena et al., 1998Allavena P. Piemonti L. Longoni D. Bernasconi S. Stoppacciaro A. Ruco L. Mantovani A. IL-10 prevents the differentiation of monocytes to dendritic cells but promotes their maturation to macrophages.Eur J Immunol. 1998; 28: 359-369Google Scholar), and (ii) histamine induces monocytes and MoDC to produce IL-10 (Elencov et al., 1998Elencov I.J. Webster E. Papanicolaou D.A. Fleisher T.A. Chrousos G.P. Wilder R.L. Histamine potently suppresses human IL-12 and stimulates IL-10 production via H2 receptors.J Immunol. 1998; 161: 2586-2593Google Scholar; Mazzoni et al., 2001Mazzoni A. Young H.A. Spitzer J.H. Visintin A. Segal D.M. Histamine regulates cytokine production in maturing dendritic cells, resulting in altered T cell polarization.J Clin Invest. 2001; 108: 1865-1873Google Scholar; Gutzmer et al., 2002Gutzmer R. Langer K. Lisewski M. Mommert S. Rieckborn D. Kapp A. Werfel T. Expression and function of histamine receptors 1 and 2 on human monocyte-derived dendritic cells.J Allergy Clin Immunol. 2002; 109: 524-531Google Scholar; Idzko et al., 2002Idzko M. la Sala A. Ferrari D. et al.Expression and function of histamine receptors in human monocyte-derived dendritic cells.J Allergy Clin Immunol. 2002; 109: 839-846Google Scholar). The mechanism by which IL-10 prevents CD1a+ DC generation remains unclear. IL-10 might exert a signal that causes monocytes to differentiate into macrophages because human blood monocytes cultured with IL-10 differentiate into CD16+ macrophage-like cells (Calzada-Wack et al., 1996Calzada-Wack J.C. Frankenberger M. Ziegler-Heitbrock H.W. Interleukin-10 drives human monocytes to CD16 positive macrophages.J Inflamm. 1996; 46: 78-85Google Scholar). Alternatively, IL-10 initiates the signal that prevents IL-4-induced signal required for DC differentiation. IL-10 upregulates the gene expression of the suppressor of cytokine-signaling (SOCS)-3 (Williams et al., 2002Williams L. Jarai G. Smith A. Finan P. IL-10 expression profiling in human monocytes.J Leukoc Biol. 2002; 72: 800-809Google Scholar). SOCS-3 inhibits IL-4-dependent signal transducer and activator of transcription (Stat) 6 activation of and subsequent gene induction (Haque et al., 2000Haque S.J. Harbor P.C. Williams B.R. Identification of critical residues required for suppressor of cytokine signaling-specific regulation of interleukin-4 signaling.J Biol Chem. 2000; 275: 26500-26506Google Scholar). Stat-mediated signals and feedback regulation by SOCS may be involved in differentiation and maturation of DC (Jackson et al., 2004Jackson S.H. Yu C.R. Mahdi R.M. Ebong S. Egwuagu C.E. Dendritic cell maturation requires STAT1 and is under feedback regulation by suppressors of cytokine signaling.J Immunol. 2004; 172: 2307-2315Google Scholar). Recently, several groups have shown that histamine alters the repertoire of cytokines secreted by LPS-matured DC that induces the polarization of naïve CD4+ T cells toward Th2 phenotypes (Caron et al., 2001Caron G. Delneste Y. Roelandts E. Duez C. Bonnefoy J.Y. Pestel J. Jeannin P. Histamine polarizes human dendritic cells into Th2 cell-promoting effector cells.J Immunol. 2001; 167: 3682-3686Google Scholar; Mazzoni et al., 2001Mazzoni A. Young H.A. Spitzer J.H. Visintin A. Segal D.M. Histamine regulates cytokine production in maturing dendritic cells, resulting in altered T cell polarization.J Clin Invest. 2001; 108: 1865-1873Google Scholar; Gutzmer et al., 2002Gutzmer R. Langer K. Lisewski M. Mommert S. Rieckborn D. Kapp A. Werfel T. Expression and function of histamine receptors 1 and 2 on human monocyte-derived dendritic cells.J Allergy Clin Immunol. 2002; 109: 524-531Google Scholar; Idzko et al., 2002Idzko M. la Sala A. Ferrari D. et al.Expression and function of histamine receptors in human monocyte-derived dendritic cells.J Allergy Clin Immunol. 2002; 109: 839-846Google Scholar). In this study, histamine-treated immature DC induced slightly but significantly increased intracellular expression of IL-4 in CD4+ naïve responder T cells, whereas the intracellular expression of IFN-γ was not significantly affected. Rather, DC generated in the presence of histamine still induced a population of Th1 cells as determined by a higher number of IFN-γ-producing cells when compared with IL-4 (Th2 cells). This may be explained by the much lower IL-10-producing capacity of histamine-treated immature DC when compared with LPS-matured, histamine-treated DC in this and previously reported experiments (Figure 4a–d). In this study, we discovered a new immunomodulatory function of histamine besides its well-characterized effects in the acute inflammatory and allergic responses; it inhibits the differentiation of CD1a+ DC mostly through the action of endogenously produced IL-10. Histamine induces monocytes to differentiate into CD1a-CD14+ DC cells even in the presence of IL-4 and GM-CSF, which have an enhanced capacity to induce the production of proinflammatory cytokines and chemokines and elevated phagocytic activity in spite of a reduced antigen-presenting capacity. This suggests that histamine-driven DC amplify antigen-independent inflammatory reactions and contribute to the exacerbation of allergic disease. Alternatively, IL-10 produced by histamine-treated monocytes and DC via H2R may induce regulatory properties of T cells because IL-10-treated DC lead to antigen-specific anergy in CD4+ T lymphocytes, which is characterized by inhibited proliferation, reduced production of IL-2, and antigen-specific suppressor activity (Jonuleit et al., 2002Jonuleit H. Schmitt E. Steinbrink K. Enk A.H. Dendritic cells as a tool to induce anergic and regulatory T cells.Trends Immunol. 2002; 23: 394-400Google Scholar; Steinbrink et al., 2002Steinbrink K. Graulich E. Kubsch S. Knop J. Enk A.H. CD4 (+) and CD8 (+) anergic T cells induced by interleukin-10-treated human dendritic cells display antigen-specific suppressor activity.Blood. 2002; 99: 2468-2476Google Scholar). The appropriate use of HR antagonists or the use of selective agonists may be promising therapeutic tools against allergic disease. FITC-labeled anti-CD1a mAb (OKT6) was obtained from Ortho Diagnostics (Raritan, New Jersey). PE-, FITC-conjugated, or uncojugated anti-CD1b, CD11b, CD14, CD40, CD45RO, CD68, CD80, CD83, CD86, HLA-DR, IL-4, IL-12 (p40/p70), TNF-α, and IFN-γ were obtained from BD PharMingen (San Diego, California). MAb against IL-10, IL-1β IL-6, and M-CSFR were purchased from R&D Systems (Minneapolis, Minnnesota). Anti-human mannose receptor (HyCult biotechnology, Uden, the Netherlands) and factor XIIIa (FXIIIa, Lab Vision, Fremont, California) mAb were also purchased. FITC-conjugated and unconjugated F(ab)2 goat anti-mouse IgG Ab were acquired from Jackson Immunoresearch (West Grove, Pennsylvania). Histamine, pyrilamine (H1R antagonist), cimetidine (H2R antagonist), thioperamine (H3R antagonist), and dimaprit dihydrochloride (H2R agonist) were obtained from Sigma Chemical Co. (St Louis, Missouri). All other reagents were obtained from Sigma Chemical Co. Whole blood was obtained from non-atopic healthy volunteers under approval of our Institutional Ethical Committee. Participants gave their written informed consent, and the study was conducted according to the Declaration of Helsinki Principles. Monocytes were isolated using Nycoprep (Nycomed, Oslo, Norway) and the Monocyte Negative Isolation Kit (Dinal Biotech, Oslo, Norway) according to the manufacturer's instructions. The monocytes were cultured with 100 ng per mL GM-CSF and IL-4, or M-CSF (R&D Systems) in low-endotoxin RPMI 1640 (Biochrom KG, Berlin, Germany) supplemented with 10% FCS, 100 mM L-glutamine, and 1% antibiotic–antimycotic (all from Gibco BRL, Gaithersburg, Maryland) for 6 d at 37°C and 5% CO2 as described previously (Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar). All plastic ware and culture reagents used were tested for the presence of endotoxin with the Limulus amebocytes lysate E-Toxate multiple test. Endotoxin levels were always <10 pg per mL. Allogeneic MLR were conducted in 96-well round-bottom microtiter plates by adding different amounts of irradiated (3000 rad) DC on day 6 to 1 × 105 allogeneic and autologus naïve CD4+ T cells, which were obtained with a CD4+ isolation kit (Dynal, Oslo, Norway), and subsequent negative selection in combination with anti-CD45RO mAb plus goat anti-mouse IgG Ab-conjugated immunomagnetic beads (Dynal). After 4 d at 37°C, cell proliferation was assessed by the uptake of [3H]thymidine (1.25 μCi per well present for 16 h; Amersham, Little Chalfont, UK). Surface and intracellular molecule labeling was performed as previously reported (Novak et al., 2001Novak N. Bieber T. Katoh N. Engagement of FcεRI on human monocytes induces the production of IL-10 and prevents their differentiation in dendritic cells.J Immunol. 2001; 167: 797-804Google Scholar). The rFI was assessed as follows: rFI=(mean fluorescence intensity (MFI) (surface molecule)–MFI (control)/MFI (control). Phagocytic activity was tested by using fluorescence-labeled latex beads (Polysciences, Wallington, Pennsylvania). Briefly, cultured cells in the absence or presence of histamine on day 5 were incubated with the beads for 3 h at 37 or 0°C. After washing three times, the cells were fixed with 4% paraformaldehyde, and then the percentage of cells that performed phagocytosis was analyzed by flow cytometry. The culture supernatant of monocytes was harvested, and the cytokine present in it was blocked as described previously (Katoh et al., 2000Katoh N. Kraft S. Weßendorf J.H.M. Bieber T. The high-affinity IgE receptor (FcεRI) blocks apoptosis in normal human monocytes.J Clin Invest. 2000; 105: 183-190Google Scholar). Briefly, monocytes were cultured for 24 h with or without 10 μM histamine. The supernatants were collected and centrifuged twice at 4°C, followed by immediate storage at -80°C. In blocking experiments, 500 μL of the supernatant was first treated with anti-cytokine neutralizing mAb (10 μg per mL) for 30 min at 37°C. Then, 20 μL of protein G-Sepharose (Amersham Pharmacia Biotech, Uppsala, Sweden) was added at 4°C for 2 h to precipitate bound cytokines. After centrifugation, the supernatant was collected, and then monocytes were cultured in the supernatants. Cytokine concentrations in the supernatants were examined by using commercially available ELISA kits (R&D Systems). Data are expressed as the means±SD. Statistical differences were determined using paired and unpaired t-tests, and a p value of less than 0.05 was considered to be statistically significant. This work is supported in part by grants from the Japanese Ministry of Education, Science, Sports and Culture, Shimizu Foundation for the Promotion of Immunology Research, and Japanese Dermatological Association for Basic Medical Research (donated by Shiseido Co. Ltd, Tokyo, Japan).
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