Expression feature of CD3, FcεRIγ, and Zap-70 in patients with chronic lymphocytic leukemia

In leukemia patients, T-cell function has been suppressed with the disease progress. Patients with chronic lymphocytic leukemia (CLL) are all to a degree immunodeficient. In order to elucidate the feature of T-cell receptor signal transduction in CLL, the expression levels of CD3γ, δ, ε, and ζ chain, FcεRIγ, and Zap-70 genes in peripheral blood mononuclear cells (PBMCs) were analyzed. Real-time polymerase chain reaction with SYBR Green technique was used for detecting the gene expression level in PBMCs from 13 patients with CLL, 13 healthy individuals, and 10 B-cell acute lymphocytic leukemia (B-ALL) served as control. The β2-microglobulin gene was used as an endogenous reference. Relative mRNA expression level of genes was analyzed by using the 2(-ΔCt) × 100% method. Significant lower expression levels of CD3γ, ε, and ζ chain genes, as well as FcεRIγ gene were found in CLL samples. Moreover, there was lost the negative correlation of the expression levels between CD3ζ and FcεRIγ genes. The expression level of Zap-70 in CLL was lower than those from healthy controls, while higher than those from B-ALL group. There was no significant correlation between the expression levels of CD3ζ and Zap-70 genes neither in the healthy group nor in the CLL group. In conclusion, the results provide a global gene expression profile of CD3γ, δ, ε, and ζ chains, and the CD3ζ-related genes FcεRIγ and Zap-70 in CLL. Deficiency of these gene expression levels might represent the feature related to T-cell immunodeficiency. The study might contribute to better understand the cellular immune features in CLL patients.     

The high affinity IgE receptor (FcεRI) expression and function in airway smooth muscle

The airway smooth muscle (ASM) is no longer considered as merely a contractile apparatus and passive recipient of growth factors, neurotransmitters and inflammatory mediators signal but a critical player in the perpetuation and modulation of airway inflammation and remodeling. In recent years, a molecular link between ASM and IgE has been established through Fc epsilon receptors (FcεRs) in modulating the phenotype and function of these cells. Particularly, the expression of high affinity IgE receptor (FcεRI) has been noted in primary human ASM cells in vitro and in vivo within bronchial biopsies of allergic asthmatic subjects. The activation of FcεRI on ASM cells suggests a critical yet almost completely ignored network which may modulate ASM cell function in allergic asthma. This review is intended to provide a historical perspective of IgE effects on ASM and highlights the recent updates in the expression and function of FcεRI, and to present future perspectives of activation of this pathway in ASM cells.     

Neutrophils orchestrate their own recruitment in murine arthritis through C5aR and FcγR signaling

Neutrophil recruitment into the joint is a hallmark of inflammatory arthritides, including rheumatoid arthritis (RA). In a mouse model of autoantibody-induced inflammatory arthritis, neutrophils infiltrate the joint via multiple chemoattractant receptors, including the leukotriene B₄ (LTB₄) receptor BLT1 and the chemokine receptors CCR1 and CXCR2. Once in the joint, neutrophils perpetuate their own recruitment by releasing LTB₄ and IL-1β, presumably after activation by immune complexes deposited on joint structures. Two pathways by which immune complexes may activate neutrophils include complement fixation, resulting in the generation of C5a, and direct engagement of Fcγ receptors (FcγRs). Previous investigations showed that this model of autoantibody-induced arthritis requires the C5a receptor C5aR and FcγRs, but the simultaneous necessity for both pathways was not understood. Here we show that C5aR and FcγRs work in sequence to initiate and sustain neutrophil recruitment in vivo. Specifically, C5aR activation of neutrophils is required for LTB₄ release and early neutrophil recruitment into the joint, whereas FcγR engagement upon neutrophils induces IL-1β release and subsequent neutrophil-active chemokine production, ensuring continued inflammation. These findings support the concept that immune complex-mediated leukocyte activation is not composed of overlapping and redundant pathways, but that each element serves a distinct and critical function in vivo, culminating in tissue inflammation.Sequential cascades of chemoattractants are a hallmark of immune cell recruitment in sterile inflammation (1, 2). We have recently shown that a lipid–cytokine–chemokine cascade, consisting of leukotriene B₄ (LTB₄)–IL-1β–neutrophil-active CCR1 and CXCR2 chemokine ligands drives neutrophil [polymorphonuclear leukocyte (PMN)] recruitment into the joint in a model of autoantibody-induced arthritis (3, 4). These mediators act in a nonredundant, sequential manner to regulate the recruitment of PMNs into the joint. Surprisingly, PMNs themselves are the predominant source of LTB₄ and IL-1β in this model, suggesting that PMNs can be central choreographers of inflammation, rather than pure effector cells (3, 5). Orchestration of PMN recruitment requires highly organized temporal and spatial patterns of chemoattractant expression (3, 6–8). The molecular mechanisms that achieve this sophisticated organization, however, are unknown and presumably differ depending on the individual pathologic stimulus and the specific tissue site. In this model of autoantibody-induced arthritis, despite progress in identifying the chemoattractants driving PMN recruitment, the specific stimuli inducing the sequential release of LTB₄ and IL-1β have not been defined.Arthritis is induced in this model by the transfer of serum from K/BxN mice into recipient mice and is therefore often referred to as the “K/BxN serum transfer model.” This model of autoantibody-induced arthritis is a prototypical model for immune complex (IC)-induced PMN-driven inflammation. K/BxN serum contains autoantibodies against glucose 6-phosphate isomerase (GPI), which form ICs on the cartilage surface (9–11). Notably, the classical pathway of complement activation does not play a role in this model, which, however, requires the complement factors C3 and C5 (9). C3 and IgG depositions colocalize in arthritic joints, implying that C3b-IgG complexes are formed on the cartilage surface, which activate complement via the alternative pathway finally cleaving C5a from C5 (9).In the K/BxN serum transfer model, adaptive immunity is bypassed and arthritis is independent of T and B lymphocytes and is instead dependent on innate immune cells and PMNs in particular (12–14). Several effector mechanisms are critically involved in the generation of arthritis in this model. In addition to LTB₄ and IL-1β, the C5a receptor (C5aR) and Fcγ receptors (FcγRs) are both also required for the development of arthritis. However, how these cell surface receptors and soluble mediators interact at the cellular level to initiate arthritis is not known.C5aR and FcγRs are central mediators of innate immunity and key for the execution of the effector phase of immune responses triggered by immune complexes (15, 16). One emerging paradigm suggests that the functions of C5aR and FcγR are intertwined and that a main function of C5aR is to lower the threshold for FcγR activation, which in turn executes the actual effector response (16–21). The relevance of this cross-regulation in vivo has been shown for autoimmune hemolytic anemia and IC-induced lung inflammation, where C5aR regulation of FcγR function occurs in Kupffer cells and alveolar macrophages, respectively (18, 19). In the latter model, this regulation enables alveolar macrophages to more efficiently direct PMN recruitment into the lung (18). However, it is not known whether this paradigm also holds true for immune responses that are not coordinated by tissue resident immune cells, and it is not known which effector mechanisms downstream of C5aR and FcγRs are required for disease induction and progression.Although it has been a matter of debate, most recent data suggest that tissue mast cells are not required for autoantibody-induced arthritis (22). The role of macrophages in this model is still debated, as macrophage-deficient op/op mice are fully susceptible to arthritis (23), whereas clodronate depletion of macrophages protects against arthritis (24). Natural killer (NK) cells and dendritic cells (DCs) are also not required for arthritis in this model (25), but compelling data suggest that PMNs are indispensable (12–14), and that C5aR and FcγR function in PMNs is required to initiate arthritis (13). However, the precise roles of C5aR and FcγR and the downstream effects of their activation on PMNs critical for the development of arthritis in this model have not been defined.In this study, we set out to identify the inducers of LTB₄ and IL-1β release from PMNs required for the pathogenesis of autoantibody-induced arthritis in this model. We hypothesized that the requirement of C5aR and FcγRs may be directly connected to the release of LTB₄ and IL-1β from PMNs. Here, we demonstrate that C5aR and FcγRs on PMNs each separately contributes to the initiation of arthritis by inducing the release of LTB₄ and IL-1β from PMNs in vivo, respectively. These findings support the concept that immune complex-mediated leukocyte activation is not composed of seemingly overlapping and redundant pathways, but that each element serves a distinct and critical function in vivo in a sequential, nonredundant manner culminating in tissue inflammation. Additionally, these results highlight how highly organized temporal and spatial patterns of chemoattractant expression can be achieved in vivo to orchestrate PMN recruitment and exemplify how PMNs can choreograph their own recruitment and inflammation.     

Development and distribution of mast cells and neuropeptides in human fetus duodenum

AIM:To study the developmental regularities and heterogeneity of mast cells(MC)in human fetus duodenum and the distribution and developmental regularities of substance P(SP),calcitonin gene-related peptide(CGRP)- immunoreactive(IR)peptidergic nerves in fetus duodenum, as well as the relationship between MC,SP and CGRP-IR peptidergic nerves. METHODS:Duodena from 21 cases of human fetus and one term infant were stained by hematoxylin-eosin(HE), toluidine blue(TB)and immunohistochemical avidin-biotinylated peroxidase complex(ABC)method. RESULTS:Lobe-shape intestinal villi in duodenum were already developed at the twelfth week.At the 21st wk, muscular mucosa appeared gradually,and four layers were observed in the wall of duodenum.TB staining showed that the granules in the immature MC were pale violet, while the mature MC were strong violet in color by TB staining.Connective tissue MC(CTMC)appeared occasionally in submucosa and muscular layer of duodenum at the 16th wk.While the mucosa MC(MMC)appeared at the 18th wk.At the 22nd wk,both CTMC and MMC were activated,and distributed in the surrounding blood vessels and ganglions.The verge of some MC were unclear,and showed degranular phenomena.At the 14th wk,SP and CGRP-IR nerve fibers and cells appeared in the myenteric and submucous plexuses in small intestine,and the responses were turn strongly.Neurons were light to deep brown,and nerve fibers were present as varicose and liner profiles.On the corresponding site of serial sections,SP and CGRP immunohistochemical reactions were coexisted in one nerve fiber or cell.Some of MC showed SP and CGRP-IR positive staining. CONCLUSION:There are two heterogeneous kinds of MC in duodenum,MMC and CTMC.MC might play an important role in regulating blood circulation and sensation.     

Differentiation between control subjects and patients with chronic spontaneous urticaria based on the ability of anti-IgE autoantibodies (AAbs) to induce FcεRI crosslinking,as compared to anti-FcεRIα AAbs

BackgroundThe reported prevalences of IgG autoantibodies (AAbs) to FcεRIα and IgE in sera from patients with chronic spontaneous urticaria (CSU) have varied, and these AAbs are also often observed in healthy control subjects. Regarding the histamine release activity of purified IgG from patients with CSU, the number of examined patients has been small. Thus, we sought to determine the prevalence and FcεRI crosslinking ability of these AAbs in a large number of patients with CSU and non-atopic control (NC) subjects.MethodsWe compared the concentrations of anti-IgE and anti-FcεRIα AAbs and the abilities of these AAbs to cause FcεRI aggregation in patients with CSU (n = 134) and NC subjects (n = 55) using ELISA and an in vitro elicitation test, respectively.ResultsThe concentration of anti-IgE AAbs was significantly different between the NC subjects and the CSU patients (P < 0.0001, cutoff value: 0.558 μg/mL), whereas the concentration of anti-FcεRIα AAbs was not. A significant difference in the duration of illness was noted between patients with lower and those with higher concentrations of anti-IgE AAbs relative to the cutoff value. The abilities of anti-IgE AAbs, but not anti-FcεRIα AAbs, to induce FcεRI crosslinking were significantly higher in CSU patients than in NC subjects (P = 0.0106).ConclusionsIn the Japanese population of CSU patients studied, the ability of the anti-IgE AAbs to induce FcεRI crosslinking differed significantly between NC subjects and CSU patients, suggesting the involvement of anti-IgE AAbs in the pathogenesis of CSU in the Japanese population.     

Impaired ('diabetic') insulin signaling and action occur in fat cells long before glucose intolerance--is insulin resistance initiated in the adipose tissue?

This review postulates and presents recent evidence that insulin resistance is initiated in the adipose tissue and also suggests that the adipose tissue may play a pivotal role in the induction of insulin resistance in the muscles and the liver. Marked impairments in insulin's intracellular signaling cascade are present in fat cells from type 2 diabetic patients, including reduced IRS-1 gene and protein expression, impaired insulin-stimulated PI3-kinase and PKB/Akt activities. In contrast, upstream insulin signaling in skeletal muscle from diabetic subjects only shows modest impairments and PKB/Akt activation in vivo by insulin appears normal. However, insulin-stimulated glucose transport and glycogen synthesis are markedly reduced.Similar marked impairments in insulin signaling, including reduced IRS-1 expression, impaired insulin-stimulated PI3-kinase and PKB/Akt activities are also seen in some (approximately 30%) normoglycemic individuals with genetic predisposition for type 2 diabetes. In addition, GLUT4 expression is markedly reduced in these cells, similar to what is seen in diabetic cells. The individuals with reduced cellular expression of IRS-1 and GLUT4 are also markedly insulin resistant and exhibit several characteristics of the Insulin Resistance Syndrome.Thus, a 'diabetic' pattern is seen in the fat cells also in normoglycemic subjects and this is associated with a marked insulin resistance in vivo. It is proposed that insulin resistance and/or its effectors is initiated in fat cells and that this may secondarily encompass other target tissues for insulin, including the impaired glucose transport in the muscles.     

Development and function of murine RORγt+ iNKT cells are under TGF-β signaling control

Invariant natural killer T (iNKT) cells have the ability to rapidly secret cytokines in response to diverse stimuli, and therefore influence numerous immune reactions. Although IFN-γ and IL-4 are thought to dominate iNKT cytokine production, a distinct subset of iNKT cells, expressing RORγt and producing IL-17, has now been identified in both mice and humans. Although a role in pathogen and allergic responses has been assigned to the RORγt(+) iNKT subset, factors controlling their development and function remain illusive. Here, we demonstrate that RORγt(+) iNKT-cell differentiation obeys transforming growth factor-β (TGF-β) signaling control, different from that described for conventional iNKT cells. We reveal that TGF-β signaling, and particularly its SMAD4-dependent pathway, is required for both the survival of RORγt(+) iNKT cells during their development and IL-17 production at the periphery. Moreover, constitutive TGF-β signaling in RORγt(+) iNKT cells drives higher peripheral numbers and increased tissue distribution. Finally, we found that SMAD4-dependent TGF-β signaling is mandatory for the peripheral expansion of the RORγt(+) iNKT cells responding to inflammatory signals. Thus, this work demonstrates that both the development and responsiveness of the newly described IL-17-producing iNKT cell subset is under the control of a dedicated TGF-β signaling pathway.     

Key role of mast cells and their major secretory products in inflammatory bowel disease

Historically,mast cells were known as a key cell type involvedin type I hypersensitivity.Until last two decades,this celltype was recognized to be widely involved in a number ofnon-allergic diseases including inflammatory bowel disease(IBD).Markedly increased numbers of mast cells wereobserved in the mucosa of the ileum and colon of patientswith IBD,which was accompanied by great changes of thecontent in mast cells such as dramatically increased expressionof TNFα,IL-16 and substance P.The evidence of mast celldegranulation was found in the wall of intestine from patientswith IBD with immunohistochemistry technique.The highlyelevated histamine and tryptase levels were detected inmucosa of patients with IBD,strongly suggesting that mastcell degranulation is involved in the pathogenesis of IBD.However,little is known of the actions of histamine,tryptase,chymase and carboxypeptidase in IBD.Over the last decade,heparin has been used to treat IBD in clinical practice.Thelow molecular weight heparin(LMWH)was effective asadjuvant therapy,and the patients showed good clinical andlaboratory response with no serious adverse effects.The rolesof PGD2,LTC4,PAF and mast cell cytokines in IBD were alsodiscussed.Recently,a series of experiments with dispersedcolon mast cells suggested there should be at least twopathways in man for mast cells to amplify their own activation-degranulation signals in an autocrine or paracrine manner.The hypothesis is that mast cell secretogogues induce mastcell degranulation,release histamine,then stimulate theadjacent mast cells or positively feedback to further stimulateits host mast cells through H_1 receptor.Whereas releasedtryptase acts similarly to histamine,but activates mast cellsthrough its receptor PAR-2.The connections between currentanti-IBD therapies or potential therapies for IBD with mastcells were discussed,implicating further that mast cell is akey cell type that is involved in the pathogenesis of IBD.Inconclusion,while pathogenesis of IBD remains unclear,thekey role of mast cells in this group of diseases demonstratedin the current review implicates strongly that IBD is a mastcell associated disease.Therefore,close attentions should bepaid to the role of mast cells in IBD.     

Mucosal mast cells are pivotal elements in inflammatory bowel disease that connect the dots： Stress, intestinal hyperpermeability and inflammation

Mast cells (MC) are pivotal elements in several physiological and immunological functions of the gastro- intestinal (GI) tract. MC translate the stress signals that has been transmitted through brain gut axis into release of proinflammatory mediators that can cause stimulation of nerve endings that could affect afferent nerve terminals and change their perception, affect intestinal motility, increase intestinal hyperpermeability and, in susceptible individuals, modulate the inflammation. Thus, it is not surprising that MC are an important element in the pathogenesis of inflammatory bowel disease and non inflammatory GI disorders such as IBS and mast cell enterocolitis.     

CD95-mediated apoptosis in naïve, central and effector memory subsets of CD4+ and CD8+ T cells in aged humans

Aging is associated with a decrease in naïve (T_N) and central memory (T_CM), and an accumulation of effector memory (T_EM and T_EMRA) T cell subsets. Previously, we have demonstrated an increased sensitivity of T_N and T_CM CD4+ and CD8+ T cells in aging to TNF-α-induced apoptosis. In this investigation, we examined whether similar differential sensitivity is applicable to CD95-mediated apoptosis. We show that T_N and T_CM CD4+ and CD8+ T cells from aged subjects are significantly more sensitive to CD95-mediated apoptosis. Increased apoptosis is associated with increased activation of caspase-8 and caspase-3. Both caspase-8 and caspase-3 inhibitors blocked CD95-mediated apoptosis and activation of caspase-8 and caspase-3 in T_N and T_CM CD4+ and CD8+ T cells. No significant difference was observed in apoptosis or in activation of caspase-8 and caspase-3 in T_EM and T_EMRA CD4+ and CD8+ T cells between young and aged subjects; both populations were relatively and comparably resistant to CD95-mediated apoptosis and caspase activation. No correlation was observed between the sensitivity/resistance of any of the subsets of CD4+ or CD8+T cells to CD95-mediated apoptosis and the expression of CD95. Our data suggest that increased CD95-mediated apoptosis of T_N and T_CM CD8+ and CD4+ T cells may play a role in their decline in human aging.     

β-Catenin in dendritic cells exerts opposite functions in cross-priming and maintenance of CD8+ T cells through regulation of IL-10

Recent studies have demonstrated that β-catenin in DCs serves as a key mediator in promoting both CD4⁺ and CD8⁺ T-cell tolerance, although how β-catenin exerts its functions remains incompletely understood. Here we report that activation of β-catenin in DCs inhibits cross-priming of CD8⁺ T cells by up-regulating mTOR-dependent IL-10, suggesting blocking β-catenin/mTOR/IL-10 signaling as a viable approach to augment CD8⁺ T-cell immunity. However, vaccination of DC–β-catenin^−/− (CD11c-specific deletion of β-catenin) mice surprisingly failed to protect them against tumor challenge. Further studies revealed that DC–β-catenin^−/− mice were deficient in generating CD8⁺ T-cell immunity despite normal clonal expansion, likely due to impaired IL-10 production by β-catenin^−/− DCs. Deletion of β-catenin in DCs or blocking IL-10 after clonal expansion similarly led to reduced CD8⁺ T cells, suggesting that β-catenin in DCs plays a positive role in CD8⁺ T-cell maintenance postclonal expansion through IL-10. Thus, our study has not only identified mTOR/IL-10 as a previously unidentified mechanism for β-catenin–dependent inhibition of cross-priming, but also uncovered an unexpected positive role that β-catenin plays in maintenance of CD8⁺ T cells. Despite β-catenin’s opposite functions in regulating CD8⁺ T-cell responses, selectively blocking β-catenin with a pharmacological inhibitor during priming phase augmented DC vaccine-induced CD8⁺ T-cell immunity and improved antitumor efficacy, suggesting manipulating β-catenin signaling as a feasible therapeutic strategy to improve DC vaccine efficacy.As the initiators of antigen-specific immune responses, dendritic cells (DCs) play a central role in regulating both T-cell immunity and tolerance (1). β-Catenin, a major component in Wnt signaling pathway, has emerged as a key factor in DC differentiation and function (2). Previous studies have shown that β-catenin regulates DC-mediated CD4⁺ T-cell responses and promotes CD4⁺ T-cell tolerance in murine models of autoimmune diseases (3, 4). Consistently, activation of β-catenin in DCs has recently been shown to suppress CD8⁺ T-cell immunity in a DC-targeted vaccine model (5), suggesting that β-catenin in DCs might similarly serve as a tolerizing signal that shifts the balance between CD8⁺ T-cell immunity and tolerance. Although the underlying mechanisms of how β-catenin mediates CD8⁺ T-cell tolerance remain largely unclear, we have shown that activation of β-catenin in DCs genetically or induced by tumors suppresses CD8⁺ T-cell immunity by inhibiting cross-priming (5). Exploiting their ability to potentiate host effector and memory CD8⁺ T-cell responses, DC vaccines have emerged as a leading strategy for cancer immunotherapy (6). However, one major obstacle for their success is host DC-mediated immunosuppression (7–9). Given that cross-priming plays a major role in generating antitumor CD8⁺ T-cell immunity (7, 10), activation of β-catenin in DCs might be a key mechanism for tumors to achieve immunosuppression. Thus, manipulating β-catenin function in cross-priming might be a viable approach to overcome DC-mediated immunosuppression and improve DC vaccine efficacy. However, The underlying mechanisms of how β-catenin in DCs achieves immunosuppression, in particular how β-catenin negatively regulates cross-priming to suppress CD8⁺ T-cell immunity, remain poorly understood.Although the mechanisms for DC-mediated priming of antitumor CD8⁺ T cells through cross-presentation remain incompletely understood, DC subsets, DC maturation status and cytokines have been shown to possibly affect their capacity in cross-priming (7, 10, 11). Although the role of cytokines in cross-priming has not been directly tested, cytokines as “signal 3” have been shown in principal to play a critical role in priming and effector differentiation of antitumor CD8⁺ T cells (12). β-Catenin in DCs has been shown to play a critical role in regulating cytokine induction (3, 4), thus suggesting that β-catenin might regulate DC cytokine production to achieve its effects on cross-priming.In this report we have identified mTOR/IL-10 signaling as a mechanism for β-catenin–dependent inhibition of cross-priming. Activation of β-catenin in DCs inhibited cross-priming of CD8⁺ T cells by up-regulating mTOR-dependent IL-10, and blocking mTOR or IL-10 led to restored cross-priming by β-catenin^active DCs. Surprisingly, mice with DC-specific deletion of β-catenin (DC–β-catenin^−/− mice) exhibited reduced antitumor immunity upon vaccination, despite the fact that deletion of β-catenin in DCs abrogated tumor-induced inhibition of cross-priming. Further studies showed that DC–β-catenin^−/− mice were deficient in generating CD8⁺ T-cell immunity despite normal clonal expansion, and β-catenin in DCs was required to maintain primed CD8⁺ T cells postclonal expansion. Thus, β-catenin in DCs exerts negative and positive functions in cross-priming and maintenance of CD8⁺ T cells, respectively. Importantly, we have demonstrated blocking β-catenin selectively at priming phase as a feasible strategy to improve DC vaccine efficacy.     

Characterization of naïve, memory and effector CD8+ T cells: effect of age

Aging is associated with progressive decline in T cell functions and increased frequency of infections, autoimmune phenomenon, and cancer. Memory T cells rapidly acquire effector functions to kill infected and malignant cells and/or inhibit their replication. Recently, memory T cells have been further classified into central and effector memory T cells (and early and intermediate T cells by some investigators). In aging, memory T cells are accumulated; however, these subpopulations of memory and effector T cells have not been fully characterized and changes in central memory and effector memory T cells in aged humans have not been described. In this article, we have further defined na?ve, central memory, effector memory, and effector CD8+ T cells in humans and their changes in aged humans.     

IL-33 augments substance P–induced VEGF secretion from human mast cells and is increased in psoriatic skin

The peptide substance P (SP) has been implicated in inflammatory conditions, such as psoriasis, where mast cells and VEGF are increased. A relationship between SP and VEGF has not been well studied, nor has any interaction with the proinflammatory cytokines, especially IL-33. Here we report that SP (0.1–10 μM) induces gene expression and secretion of VEGF from human LAD2 mast cells and human umbilical core blood-derived cultured mast cells (hCBMCs). This effect is significantly increased by coadministration of IL-33 (5–100 ng/mL) in both cell types. The effect of SP on VEGF release is inhibited by treatment with the NK-1 receptor antagonist 733,060. SP rapidly increases cytosolic calcium, and so does IL-33 to a smaller extent; the addition of IL-33 augments the calcium increase. SP-induced VEGF production involves calcium-dependent PKC isoforms, as well as the ERK and JNK MAPKs. Gene expression of IL-33 and histidine decarboxylase (HDC), an indicator of mast cell presence/activation, is significantly increased in affected and unaffected (at least 15 cm away from the lesion) psoriatic skin, as compared with normal control skin. Immunohistochemistry indicates that IL-33 is associated with endothelial cells in both the unaffected and affected sites, but is stronger and also associated with immune cells in the affected site. These results imply that functional interactions among SP, IL-33, and mast cells leading to VEGF release contribute to inflammatory conditions, such as the psoriasis, a nonallergic hyperproliferative skin inflammatory disorder with a neurogenic component.