Activation of Th1 lymphocytes, IFN-gamma production and macrophage activation are crucial in defense against Mycobacteria. In developing countries, Th2 activation and IL-4 production have been associated in vitro with tuberculosis and with poor clinical outcome after treatment. Serological markers of Th1 [soluble lymphocyte activation gene (LAG)-3] and Th2 (IgE, solubleCD30, and CCL22/macrophage-derived chemokine) activity were measured in 414 HIV-negative tuberculosis patients from The Gambia and Guinée and in 414 healthy household and community controls. Measurements were repeated during treatment to assess the effect of therapy on Th1/Th2 ratio. At diagnosis, sLAG-3 levels were lower in patients than in community controls (p<0.0001), but were higher in household controls exposed to contact with patients than in community controls (p<0.0001). In comparison with community controls, patients had consistently higher levels of IgE, sCD30, and CCL22 (p<0.0001), whereas household controls had lower levels of indicators of Th2 activity (p<0.0001). After treatment, cured patients had higher levels of Th1 (p<0.0001) and lower levels of Th2 (p<0.0001) activity than patients who were not successfully treated or interrupted therapy. In Africa, tuberculosis is associated with low Th1 and high Th2 activity in vivo, whereas close exposure to tuberculosis is associated with a high Th1/Th2 ratio. Patients with favorable outcome after treatment exhibit a higher Th1/Th2 ratio compared to patients with poor clinical outcome.

Activation of vitamin D receptor (VDR) by 1,25-dihydroxyvitamin D(3) (1,25-vitD) reprograms dendritic cells (DC) to become tolerogenic. Previous studies suggested that 1,25-vitD could inhibit the changes brought about by differentiation and maturation of DCs. Underpinning the described phenotypic and functional alterations, there must be 1,25-vitD-coordinated transcriptional events. However, this transcriptional program has not been systematically investigated, particularly not in a developmental context. Hence, it has not been explored how 1,25-vitD-regulated genes, particularly the ones bringing about the tolerogenic phenotype, are connected to differentiation. We conducted global gene expression analysis followed by comprehensive quantitative PCR validation to clarify the interrelationship between 1,25-vitD and differentiation-driven gene expression patterns in developing human monocyte-derived and blood myeloid DCs. In this study we show that 1,25-vitD regulates a large set of genes that are not affected by differentiation. Interestingly, several genes, impacted both by the ligand and by differentiation, appear to be regulated by 1,25-vitD independently of the developmental context. We have also characterized the kinetics of generation of 1,25-vitD by using three early and robustly regulated genes, the chemokine CCL22, the inhibitory receptors CD300LF and CYP24A1. We found that monocyte-derived DCs are able to turn on 1,25-vitD sensitive genes in early phases of differentiation if the precursor is present. Our data collectively suggest that exogenous or endogenously generated 1,25-vitD regulates a large set of its targets autonomously and not via inhibition of differentiation and maturation, leading to the previously characterized tolerogenic state.

Regulatory T cells (Tregs) may impede cancer vaccine efficacy in hematologic malignancies and cancer. CCR4 antagonists, an emergent class of Treg inhibitor, have been shown to block recruitment of Tregs mediated by CCL22 and CCL17. Our aim was to demonstrate the ability of a CCR4 antagonist (a small chemical molecule identified in silico) when combined with vaccines to break peripheral tolerance controlled by Tregs, a prerequisite for the induction of CD8(+) T cells against self Ags. Immunization of transgenic or normal mice expressing tumor-associated self Ags (Her2/neu, OVA, gp100) with a CCR4 antagonist combined with various vaccines led to the induction of effector CD8(+) T cells and partial inhibition of tumor growth expressing self Ags in both prophylactic and therapeutic settings. The CCR4 antagonist was more efficient than cyclophosphamide to elicit anti-self CD8(+) T cells. We also showed that the population of Tregs expressing CCR4 corresponded to memory (CD44(high)) and activated (ICOS(+)) Tregs, an important population to be targeted to modulate Treg activity. CCR4 antagonist represents a competitive class of Treg inhibitor able to induce functional anti-self CD8(+) T cells and tumor growth inhibition when combined with vaccines. High expression of CCR4 on human Tregs also supports the clinical development of this strategy.

Tumor infiltration with effector CD8(+) T cells (T(eff)) predicts longer recurrence-free survival in many types of human cancer, illustrating the broad significance of T(eff) for effective immunosurveillance. Colorectal tumors with reduced accumulation of T(eff) express low levels of T(eff)-attracting chemokines such as CXCL10/IP10 and CCL5/RANTES. In this study, we investigated the feasibility of enhancing tumor production of T(eff)-attracting chemokines as a cancer therapeutic strategy using a tissue explant culture system to analyze chemokine induction in intact tumor tissues. In different tumor explants, we observed highly heterogeneous responses to IFNα or poly-I:C (a TLR3 ligand) when they were applied individually. In contrast, a combination of IFNα and poly-I:C uniformly enhanced the production of CXCL10 and CCL5 in all tumor lesions. Moreover, these effects could be optimized by the further addition of COX inhibitors. Applying this triple combination also uniformly suppressed the production of CCL22/MDC, a chemokine associated with infiltration of T regulatory cells (T(reg)). The T(eff)-enhancing effects of this treatment occurred selectively in tumor tissues, as compared with tissues derived from tumor margins. These effects relied on the increased propensity of tumor-associated cells (mostly fibroblasts and infiltrating inflammatory cells) to hyperactivate NF-κB and produce T(eff)-attracting chemokines in response to treatment, resulting in an enhanced ability of the treated tumors to attract T(eff) cells and reduced ability to attract T(reg) cells. Together, our findings suggest the feasibility of exploiting NF-κB hyperactivation in the tumor microenvironment to selectively enhance T(eff) entry into colon tumors.

Ibrutinib (PCI-32765) is a highly potent oral Bruton tyrosine kinase (BTK) inhibitor in clinical development for treating B-cell lymphoproliferative diseases. Patients with chronic lymphocytic leukemia (CLL) often show marked, transient increases of circulating CLL cells following ibrutinib treatments, as seen with other inhibitors of the B-cell receptor (BCR) pathway. In a phase 1 study of ibrutinib, we noted similar effects in patients with mantle cell lymphoma (MCL). Here, we characterize the patterns and phenotypes of cells mobilized among patients with MCL and further investigate the mechanism of this effect. Peripheral blood CD19(+)CD5(+) cells from MCL patients were found to have significant reduction in the expression of CXCR4, CD38, and Ki67 after 7 days of treatment. In addition, plasma chemokines such as CCL22, CCL4, and CXCL13 were reduced 40% to 60% after treatment. Mechanistically, ibrutinib inhibited BCR- and chemokine-mediated adhesion and chemotaxis of MCL cell lines and dose-dependently inhibited BCR, stromal cell, and CXCL12/CXCL13 stimulations of pBTK, pPLCγ2, pERK, or pAKT. Importantly, ibrutinib inhibited migration of MCL cells beneath stromal cells in coculture. We propose that BTK is essential for the homing of MCL cells into lymphoid tissues, and its inhibition results in an egress of malignant cells into peripheral blood. This trial was registered at www.clinicaltrials.gov as #NCT00114738.

OBJECTIVE

Mesenchymal stem cells (MSCs) are pluripotent cells that can promote expansion of immune regulatory cells and might be developed for the treatment of immune disorders, including inflammatory bowel diseases. MSCs were reported to reduce colitis in mice; we investigated whether MSC localization to the intestine and production of paracrine factors, including tumor necrosis factor-induced protein 6 (TSG6), were required for these effects.

METHODS

MSCs were isolated from bone marrow (BM-MSCs) of 4- to 6-week-old C57BL/6, C57BL/6-green fluorescent protein, or Balb/c Tsg6-/- male mice. Colitis was induced by ad libitum administration of dextran sulfate sodium for 10 days; after 5 days the mice were given intraperitoneal injections of BM-MSCs or saline (controls). Blood samples and intestinal tissues were collected 24, 48, 96, and 120 hours later; histologic and flow cytometry analyses were performed.

RESULTS

Injection of BM-MSCs reduced colitis in mice, increasing body weight and reducing markers of intestinal inflammation, compared with control mice. However, fewer than 1% of MSCs reached the inflamed colon. Most of the BM-MSCs formed aggregates in the peritoneal cavity. The aggregates contained macrophages and B and T cells, and produced immune-regulatory molecules including FOXP3, interleukin (IL)10, transforming growth factor-β, arginase type II, chemokine (C-C motif) ligand 22 (CCL22), heme oxygenase-1, and TSG6. Serum from mice given BM-MSCs, compared with mice given saline, had increased levels of TSG6. Injection of TSG6 reduced the severity of colitis in mice, along with the numbers of CD45+ cells, neutrophils and metalloproteinase activity in the mucosa, while increasing the percentage of Foxp3CD45+ cells. TSG6 injection also promoted the expansion of regulatory macrophages that expressed IL10 and inducible nitric oxide synthase, and reduced serum levels of interferon-γ, IL6, and tumor necrosis factor. Tsg6-/- MSCs did not suppress the mucosal inflammatory response in mice with colitis.

CONCLUSIONS

BM-MSCs injected into mice with colitis do not localize to the intestine but instead form aggregates in the peritoneum where they produce immunoregulatory molecules, including TSG6, that reduce intestinal inflammation. TSG6 is sufficient to reduce intestinal inflammation in mice with colitis.

The role of specific chemokine receptors during allergic asthmatic responses has been relatively undefined. A number of receptors are preferentially expressed on Th2 cells, including CCR4, CCR8, and CxCR4. In the present study, we have examined the role of CxCR4 in the development of cockroach allergen-induced inflammation and airway hyperreactivity in a mouse model of asthma. Using a specific inhibitor of CxCR4, AMD3100, our results indicate that blocking this receptor has a significant effect in down-regulating the inflammation and pathophysiology of the allergen-induced response. Treatment of allergic mice with AMD3100 significantly reduced airway hyperreactivity, peribronchial eosinophilia, and the overall inflammatory responses. In addition, there was a shift in the cytokine profile that was observed in the AMD3100-treated animals. Specifically, there was a significant reduction in interleukin-4 and interleukin-5 levels and a significant increase in interleukin-12 and interferon-gamma levels within the lungs of treated allergic mice. Furthermore, there was a significant alteration in the local chemokine production of CCL22 (MDC) and CCL17 (TARC), two chemokines previously shown to be important in Th2-type allergen responses. Overall, specifically blocking CxCR4 using AMD3100 reduced a number of pathological parameters related to asthmatic-type inflammation.

Lymphoid neogenesis is associated with antibody-mediated autoimmune diseases such as Sjogren's syndrome and rheumatoid arthritis. Although systemic lupus erythematosus is the prototypical B-cell-mediated autoimmune disease, the role of lymphoid neogenesis in its pathogenesis is unknown. Intraperitoneal injection of 2,6,10,14-tetramethyl-pentadecane (TMPD, pristane) or mineral oil causes lipogranuloma formation in mice, but only TMPD-treated mice develop lupus. We report that lipogranulomas are a form of lymphoid neogenesis. Immunoperoxidase staining of lipogranulomas revealed B cells, CD4(+) T cells, and dendritic cells and in some cases organization into T- and B-cell zones. Lipogranulomas also expressed the lymphoid chemokines CCL21, CCL19, CXCL13, CXCL12, and CCL22. Expression of the type I interferon (IFN-I)-inducible genes Mx1, IRF7, IP-10, and ISG-15 was greatly increased in TMPD- versus mineral oil-induced lipogranulomas. Dendritic cells from TMPD lipogranulomas underwent activation/maturation with high CD86 and interleukin-12 expression. Magnetic bead depletion of dendritic cells markedly diminished IFN-inducible gene (Mx1) expression. We conclude that TMPD-induced lupus is associated with the formation of ectopic lymphoid tissue containing activated dendritic cells producing IFN-I and interleukin-12. In view of the increased IFN-I production in systemic lupus erythematosus, these studies suggest that IFN-I from ectopic lymphoid tissue could play a role in the pathogenesis of experimental lupus in mice.

Activation-induced cytidine deaminase (AID) is necessary for immunoglobulin somatic hypermutation (SHM) and class switch recombination (CSR) in T-dependent immune response in germinal centers (GCs). The structural similarity of AID with RNA-editing enzymes and its largely cytoplasmic location have fueled controversial views of its mode of interaction with DNA. We show that AID, a mature B-cell-restricted cytoplasmic antigen, is relocated into the nucleus in 2.5% of CDKN1B(-), CCNB1(-) GC cells. The GC dark zone and the outer zone (OZ), but not the light zone, contain nuclear and cytoplasmic AID(+) blasts. AID(+) cells in the OZ are in contact with T cells and CD23(-) follicular dendritic cells. In addition, AID is expressed in extrafollicular large proliferating B cells, 14% of which have nuclear AID. GC and extrafollicular AID(+) cells express E47 but not the inhibiting BHLH protein Id2. Outside the GC, AID(+) B cells are in contact with T cells and show partial evidence of CD40 plus bcr stimulation-dependent signature (CCL22, JunB, cMYC, CD30) but lack early and late plasma cell markers. The distribution of nuclear AID is consistent with the topography of SHM and CSR inside the GC and in extrafollicular activated B cells.

IL-17-producing CD4(+) T (Th17) cells have been found to be increased in some human cancers; however, the possible implication of Th17 cells in regulating antitumor responses in malignant pleural effusion (MPE) remains to be elucidated. In the current study, distribution and phenotypic features of Th17 cells in both MPE and peripheral blood from patients with lung cancer were determined by flow cytometry or double immunofluorescence staining. The impacts of cytokines on Th17 cell generation and differentiation were explored. The chemoattractant activity of chemokines CCL20 and CCL22 for Th17 cells in vitro was also observed. It was found that the increased Th17 cells could be found in MPE compared with blood. The in vitro experiments showed that IL-1β, IL-6, IL-23, or their various combinations could promote Th17 cell generation and differentiation from naive CD4(+) T cells. MPE was chemotactic for Th17 cells, and this activity was partly blocked by anti-CCL20 and/or CCL22 Abs. Our data also showed that the accumulation of Th17 cells in MPE predicted improved patient survival. It could be concluded that the overrepresentation of Th17 cells in MPE might be due to Th17 cell differentiation and expansion stimulated by pleural proinflammatory cytokines and to recruitment of Th17 cells from peripheral blood induced by pleural chemokines CCL20 and CCL22. Furthermore, the accumulation of Th17 cells in MPE predicted improved patient survival. These data provide the basis for developing immune-boosting strategies based on ridding the cancer patient of this cell population.

Macrophage-derived chemokine (MDC)/CCL22 is a CC chemokine active on dendritic cells (DC), NK cells and Th2 lymphocytes. The present study was aimed at comprehensively investigating MDC production in vitro and in vivo. DC were the most potent producers of MDC among leukocytes tested. Endothelial cells did not produce MDC under a variety of conditions. Signals that induce maturation (lipopolysaccharide, IL-1, TNF, CD40 ligand, recognition of bacteria and yeast) dramatically augmented MDC production, and dexamethasone and vitamin D3 blocked it. Prostaglandin E(2), which blocked the acquisition of IL-12 production and the capacity to promote Th1 generation, did not affect MDC production. Using mass spectrometry-based techniques, DC supernatants were found to contain N-terminally truncated forms of MDC [MDC(3-69), MDC(5-69) and MD(C7-69)] as well as the full-length molecule. In vivo, CD1a(+), CD83(+), MDC(+) DC were found in reactive lymph nodes, and in Langerhans' cell histiocytosis. Skin lesions of atopic dermatitis patients showed that CD1a(+) or CD1b(+) DC, and DC with a CD83(+) phenotype were responsible for MDC production in this Th2-oriented disorder. Thus, DC are the predominant source of MDC in vitro and in vivo under a variety of experimental and clinical conditions. Processing of MDC to MDC(3-69) and shorter forms which do not recognize CCR4 is likely to represent a feedback mechanism of negative regulation.

BACKGROUND

The development of a safe and effective AD vaccine requires a delicate balance between providing an adequate anti-Abeta antibody response sufficient to provide therapeutic benefit, while eliminating an adverse T cell-mediated proinflammatory autoimmune response. To achieve this goal we have designed a prototype chemokine-based DNA epitope vaccine expressing a fusion protein that consists of 3 copies of the self-B cell epitope of Abeta(42) (Abeta(1-11)) , a non-self T helper cell epitope (PADRE), and macrophage-derived chemokine (MDC/CCL22) as a molecular adjuvant to promote a strong anti-inflammatory Th2 phenotype.

RESULTS

We generated pMDC-3Abeta(1-11)-PADRE construct and immunized 3xTg-AD mouse model starting at age of 3-4 months old. We demonstrated that prophylactic immunizations with the DNA epitope vaccine generated a robust Th2 immune response that induced high titers of anti-Abeta antibody, which in turn inhibited accumulation of Abeta pathology in the brains of older mice. Importantly, vaccination reduced glial activation and prevented the development of behavioral deficits in aged animals without increasing the incidence of microhemorrhages.

CONCLUSIONS

Data from this transitional pre-clinical study suggest that our DNA epitope vaccine could be used as a safe and effective strategy for AD therapy. Future safety and immunology studies in large animals with the goal to achieve effective humoral immunity without adverse effects should help to translate this study to human clinical trials.

Leukocyte trafficking, which is critically regulated by chemokines and their receptors, shares many of the characteristics of tumor cell infiltration and metastasis. Expression of CC chemokine receptor 4 (CCR4) by tumor cells is associated with skin involvement, but CCR4 also has an important role in normal and tumor immunity. In a subset of patients with CCR4(+) T-cell leukemia/lymphoma, the tumor cells themselves function as regulatory T (Treg) cells, contributing to tumor survival in the face of host antitumor immune responses. In other types of cancers, the chemokines TARC/CCL17 and MDC/CCL22, specific ligands for CCR4 that are produced by tumor cells and the tumor microenvironment, attract CCR4(+) Treg cells to the tumor, where they create a favorable environment for tumor escape from host immune responses. A novel humanized anti-CCR4 monoclonal antibody (mAb) has been developed, the Fc region of which is defucosylated to enhance antibody-dependent cellular cytotoxicity by increasing its binding affinity to Fc receptor on effector cells. We are now conducting a phase I clinical trial of this anti-CCR4 mAb in patients with CCR4(+) T-cell leukemia/lymphoma in Japan (clinical trials gov. identifier: NCT00355472). Anti-CCR4 mAb could be an ideal treatment modality for many different cancers, not only to directly kill the CCR4(+) tumor cells, but also to overcome the suppressive effect of CCR4(+) Treg cells on the host immune response to tumor cells.

CC chemokine ligand 1 (CCL1; I-309) is a CC chemokine that interacts with CC chemokine receptor 8, which is preferentially expressed in polarized T helper cell type 2 and Tc2 cells, in eosinophils, and in T regulatory cells. The present study, prompted by transcriptional profiling of human monocytes undergoing different forms of activation, was designed to characterize the production of CCL1 in monocytes compared with the production of other chemokines (CCL2, CCL22, and CCL18) differentially regulated by distinct activation signals. Lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), interleukin (IL)-1beta, tumor necrosis factor alpha, IL-4, IL-13, IL-10, IL-6, IL-18, and combinations thereof did not induce CCL1 production in monocytes, and some of these signals stimulated production of reference chemokines. Induction of CCL1 in monocytes required engagement of Fc receptor for immunoglobulin G (FcgammaR)II and exposure to IL-1beta or LPS. This combination of stimuli results in a form of M2 (M2b, Type 2) macrophage activation. FcgammaR engagement also induced CCL22 and amplified its stimulation by IL-4. In contrast, FcgammaR stimulation inhibited the IL-10- and LPS-mediated induction of CCL18. IL-10, IL-4, and IFN-gamma inhibited induction of CCL1 by FcgammaR ligation and IL-1beta. CCL1 was present in synovial fluids and macrophages in juvenile idiopathic arthritis. Thus, regulation of CCL1 in human monocytes is unique, with an obligate requirement of FcgammaR engagement and costimulation by signals (IL-1beta and LPS), which use the myeloid differentiation primary-response protein 88 adaptor protein. Thus, CCL1 is a CC chemokine with a unique pattern of regulation associated with a distinct form of M2 (Type 2, M2b) monocyte activation, which participates in macrophage-dependent regulatory circuits of innate and adaptive immunity.

To examine the different roles of myeloid dendritic cells (M-DCs) and plasmacytoid dendritic cells (P-DCs) in the induction and regulation of immune response, we have studied chemokine secretion by freshly isolated DC subsets in response to bacterial, viral, and T cell-derived stimuli. M-DCs selectively produced very high levels of the homeostatic chemokines CC chemokine ligand (CCL)17 and CCL22, while P-DCs produced very little if any. In contrast, the proinflammatory chemokine CCL3 was secreted mostly by P-DCs, whereas CCL4 and CXC chemokine ligand 8 were produced by both subsets. The selective production of CCL17 and CCL22 by M-DCs but not P-DCs was confirmed in vivo by immunohistology on human reactive lymph node sections. The high production of CCR4 ligands by M-DCs suggests their capacity to selectively recruit at sites of inflammation T cells with regulatory properties or with a Th2 phenotype, whereas P-DCs, by preferentially secreting CCR1/CCR5 ligands, would mostly recruit effector T cells and, in particular, Th1-type cells.

Previous interethnic comparative studies on the susceptibility to malaria performed in West Africa showed that Fulani are more resistant to Plasmodium falciparum malaria than are sympatric ethnic groups. This lower susceptibility is not associated to classic malaria-resistance genes, and the analysis of the immune response to P. falciparum sporozoite and blood stage antigens, as well as non-malaria antigens, revealed higher immune reactivity in Fulani. In the present study we compared the expression profile of a panel of genes involved in immune response in peripheral blood mononuclear cells (PBMC) from Fulani and sympatric Mossi from Burkina Faso. An increased expression of T helper 1 (TH1)-related genes (IL-18, IFNgamma, and TBX21) and TH2-related genes (IL-4 and GATA3) and a reduced expression of genes distinctive of T regulatory activity (CTLA4 and FOXP3) were observed in Fulani. Microarray analysis on RNA from CD4+ CD25+ (T regulatory) cells, performed with a panel of cDNA probes specific for 96 genes involved in immune modulation, indicated obvious differences between the two ethnic groups with 23% of genes, including TGFbeta, TGFbetaRs, CTLA4, and FOXP3, less expressed in Fulani compared with Mossi and European donors not exposed to malaria. As further indications of a low T regulatory cell activity, Fulani showed lower serum levels of TGFbeta and higher concentrations of the proinflammatory chemokines CXCL10 and CCL22 compared with Mossi; moreover, the proliferative response of Fulani to malaria antigens was not affected by the depletion of CD25+ regulatory cells whereas that of Mossi was significantly increased. The results suggest that the higher resistance to malaria of the Fulani could derive from a functional deficit of T regulatory cells.

Macrophage-derived chemokine (MDC, CCL22) is a member of the CC-chemokine family and is composed of 69 amino acid residues. MDC is mainly produced by macrophages and dendritic cells upon the stimulation with microbial products, or anti-CD40 antibody, and is upregulated by TH2-type cytokines, such as IL-4 and -5, but is downregulated by TH1-type cytokines, such as IFN-gamma. MDC-production is also upregulated by prostaglandin and cyclic AMP-elevating agents. MDC causes chemotactic migration of dendritic cells and TH2 cells. Furthermore, MDC is highly-expressed in the lesions of TH2-related diseases, such as airway hypersensitivity and atopic dermatitis. Thus, MDC plays an important role in the recruitment of TH2 cells into the inflammatory sites and the regulation of TH2-related immune responses.

Peroxisome proliferator-activated receptor gamma (PPARgamma ), a member of the nuclear receptor superfamily, has recently been described as a modulator of macrophage functions and as an inhibitor of T cell proliferation. Here, we investigated the role of PPARgamma in dendritic cells (DC), the most potent antigen-presenting cells. We showed that PPARgamma is highly expressed in immature human monocyte-derived DC (MDDC) and that it may affect the immunostimulatory function of MDDC stimulated with lipopolysaccharide (LPS) or via CD40 ligand (CD40L). We found that the synthetic PPARgamma agonist rosiglitazone (as well as pioglitazone and troglitazone) significantly increases on LPS- and CD40L-activated MDDC, the surface expression of CD36 (by 184% and 104%, respectively) and CD86 (by 54% and 48%), whereas it reduces the synthesis of CD80 (by 42% and 42%). Moreover, activation of PPARgamma resulted in a dramatic decreased secretion of the Th1-promoting factor IL-12 in LPS- and CD40L-stimulated cells (by 47% and 62%), while the production of IL-1beta, TNF-alpha, IL-6 and IL-10 was unaffected. Finally, PPARgamma ligands down-modulate the synthesis of IFN-gamma -inducible protein-10 (recently termed as CXCL10) and RANTES (CCL5), both chemokines involved in the recruitment of Th1 lymphocytes (by 49% and 30%), but not the levels of the Th2 cell-attracting chemokines,macrophage-derived chemokine (CCL22) and thymus and activation regulated chemokine (CCL17), in mature MDDC. Taken together, our data suggest that activation of PPARgamma in human DC may have an impact in the orientation of primary and secondary immune responses by favoring type 2 responses.

Chemokines are likely to play important roles in the pathophysiology of diseases associated with Epstein-Barr virus (EBV). Here, we have analyzed the repertoire of chemokines expressed by EBV-infected B cells. EBV infection of B cells induced expression of TARC/CCL17 and MDC/CCL22, which are known to attract Th2 cells and regulatory T cells via CCR4, and also upregulated constitutive expression of MIP-1 alpha/CCL3, MIP-1 beta/CCL4, and RANTES/CCL5, which are known to attract Th1 cells and cytotoxic T cells via CCR5. Accordingly, EBV-immortalized B cells secreted these chemokines, especially CCL3, CCL4, and CCL22, in large quantities. EBV infection or stable expression of LMP1 also induced CCL17 and CCL22 in a B-cell line, BJAB. The inhibitors of the TRAF/NF-kappa B pathway (BAY11-7082) and the p38/ATF2 pathway (SB202190) selectively suppressed the expression of CCL17 and CCL22 in EBV-immortalized B cells and BJAB-LMP1. Consistently, transient-transfection assays using CCL22 promoter-reporter constructs demonstrated that two NF-kappa B sites and a single AP-1 site were involved in the activation of the CCL22 promoter by LMP1. Finally, serum CCL22 levels were significantly elevated in infectious mononucleosis. Collectively, LMP1 induces CCL17 and CCL22 in EBV-infected B cells via activation of NF-kappa B and probably ATF2. Production of CCL17 and CCL22, which attract Th2 and regulatory T cells, may help EBV-infected B cells evade immune surveillance by Th1 cells. However, the concomitant production of CCL3, CCL4, and CCL5 by EBV-infected B cells may eventually attract Th1 cells and cytotoxic T cells, leading to elimination of EBV-infected B cells at latency III and to selection of those with limited expression of latent genes.

Relapsed or refractory (rel/ref) classical Hodgkin lymphoma (cHL) remains a clinical challenge, with limited effective treatment options available after stem cell transplantation. In a multicenter phase 2 study, the efficacy of lenalidomide in rel/ref cHL patients was evaluated at a dose of 25 mg/d on days 1-21 of a 28-day cycle. Patients remained on lenalidomide until disease progression or an unacceptable adverse event (AE) occurred. Thirty-eight cHL patients were enrolled with a median of 4 (range, 2-9) prior therapies; 87% had undergone prior stem cell transplantation and 55% of patients did not respond to their last prior therapy. Of 36 evaluable patients, responses were 1 complete remission (CR), 6 partial remissions (PRs), and 5 patients with stable disease (SD) for ≥ 6 months resulting in an International Working Committee (IWC) objective overall response rate (ORR) of 19% and a cytostatic ORR of 33%. Decreased chemokine (CCL17 and CCL22) plasma levels at 2 weeks were associated with a subsequent response. The treatment was well tolerated, and the most common grade 3/4 AEs were neutropenia (47%), anemia (29%), and thrombocytopenia (18%). Four patients discontinued lenalidomide because of rash, elevated transaminases/bilirubin, and cytopenias. We provide preliminary evidence of lenalidomide's activity in patients with rel/ref cHL, and therefore exploration of lenalidomide in combination with other active agents is warranted. This trial is registered at www.ClinicalTrials.gov as NCT00540007.

BACKGROUND

As Th2 type lymphocytes orchestrate the cardinal features of allergic asthma, inhibiting their recruitment to the lungs could be of therapeutic benefit. Although human Th2 cells express the CCR4 chemokine receptor and increased production of CCR4 ligands has been found in asthmatic airways, studies in animals have reached contradictory conclusions on whether blocking this pathway would be beneficial.

OBJECTIVE

As a lack of efficacy might be due to differences between mouse and man, we readdressed this question using a humanized severe combined immunodeficiency model of asthma.

METHODS

Mice received peripheral blood mononuclear cells from house dust mite (HDM) allergic asthmatic patients and then underwent bronchial challenge with HDM.

RESULTS

This resulted in marked allergic inflammation and bronchial hyper-reactivity. Administration of CCR4 blocking antibody abolished the airway eosinophilia, goblet cell hyperplasia, IgE synthesis and bronchial hyper-reactivity. In this chimeric system, human CD11c+ dendritic cells (DCs) were the predominant source of CCR4 ligands, suggesting that DC-derived chemokines attract Th2 cells. In separate experiments using human DCs, in vitro exposure to HDM of DCs from HDM allergic patients but not healthy controls caused CCL17 and CCL22 release that resulted in chemoattraction of polarized human Th2 cells in a CCR4-dependent way.

CONCLUSIONS

Taken together, our data provide proof of concept that CCR4 blockade inhibits the salient features of asthma and justify further clinical development of CCR4 antagonists for this disease.

BACKGROUND

Atopic dermatitis (AD) and psoriasis represent contrasting poles of the T(H)1 versus T(H)2 paradigm. Both diseases have been associated with increased numbers of dendritic cells (DCs) in the skin, but the similarities and differences in DC populations need to be established.

OBJECTIVE

We aimed to characterize the specific DC subsets, as well as chemokine and cytokine environment in chronic AD compared with psoriasis.

METHODS

Skin biopsies were obtained from patients with acute exacerbation of chronic AD (n = 18), psoriasis (n = 15), and healthy volunteers (n = 15) for microarray analysis, RT-PCR, immunohistochemistry, and double-label immunofluorescence.

RESULTS

Myeloid DCs upregulate CCL17 and CCL18 in AD, as opposed to TNF-alpha and inducible nitric oxide synthase (iNOS) in psoriasis. In our study, we identified cells phenotypically identical to the inflammatory dendritic epidermal cells in the dermis in both diseases, although to a lesser extent in psoriasis. We found substantially higher numbers of dermal CCL22 producing plasmacytoid DCs in AD. The thymic stromal lymphopoietin receptor showed significantly higher expression in AD, whereas the thymic stromal lymphopoietin ligand was upregulated more in psoriasis.

CONCLUSIONS

There are major differences in myeloid and plasmacytoid subsets of cutaneous DCs and the chemokine/cytokine environment between AD and psoriasis. Distinct subsets within the CD11c(+) population may influence polarization through the production of regulatory mediators, including iNOS, TNF, CCL17, and CCL18. Plasmacytoid DCs may also influence T(H)2 polarization, having a more important role in AD than previously appreciated.

CONCLUSIONS

Dermal inflammatory dendritic cells in AD and TNF and iNOS-producing DCs in psoriasis, and/or their regulatory products, may be potential targets for future therapeutic interventions.

Sensitization to fungi, such as the mold Aspergillus fumigatus, is increasingly becoming linked with asthma severity. We have previously shown that lung responses generated via the β-glucan receptor Dectin-1 are required for lung defense during acute, invasive A. fumigatus infection. Unexpectedly, in an allergic model of chronic lung exposure to live A. fumigatus conidia, β-glucan recognition via Dectin-1 led to the induction of multiple proallergic (Muc5ac, Clca3, CCL17, CCL22, and IL-33) and proinflammatory (IL-1β and CXCL1) mediators that compromised lung function. Attenuated proallergic and proinflammatory responses in the absence of Dectin-1 were not associated with changes in Ido (IDO), Il12p35/Ebi3 (IL-35), IL-10, or TGF-β levels. Assessment of Th responses demonstrated that purified lung CD4(+) T cells produced IL-4, IL-13, IFN-γ, and IL-17A, but not IL-22, in a Dectin-1-dependent manner. In contrast, we observed robust, Dectin-1-dependent IL-22 production by unfractionated lung digest cells. Intriguingly, the absence of IL-22 alone mimicked the attenuated proallergic and proinflammatory responses observed in the absence of Dectin-1, suggesting that Dectin-1-mediated IL-22 production potentiated responses that led to decrements in lung function. To this end, neutralization of IL-22 improved lung function in normal mice. Collectively, these results indicate that the β-glucan receptor Dectin-1 contributes to lung inflammation and immunopathology associated with persistent fungal exposure via the production of IL-22.

DNA immunizations with glycoprotein 120 (gp120) of human immunodeficiency virus-1 (HIV-1) usually require boosting with protein or viral vaccines to achieve optimal efficacy. Here, we demonstrate for the first time that mice immunized with DNA encoding gp120 fused with proinflammatory chemoattractants of immature dendritic cells, such as beta-defensin 2, monocyte chemoattractant protein-3 (MCP-3/CCL7) or macrophage-derived chemokine (MDC/CCL22), elicited anti-gp120 antibodies with high titers of virus-neutralizing activity. The immunogenicity was further augmented with the use of chemokine fusion constructs with gp140, gp120 linked to the extracellular domain of gp41 via a 14-amino acid spacer peptide sequence. This construct elicited antibodies with more effective neutralizing activity than corresponding constructs expressing gp120. Responses were dependent on physical linkage with chemokine moiety, as no immunity was detected following immunization of mice with DNA encoding a free mixture of chemokine and gp120. Although the route of immunization was inoculation into skin, both systemic and mucosal CD8(+) cytolytic immune responses were elicited in mice immunized with DNA expressing MCP-3 or beta-defensin 2 fusion constructs. In contrast, no cytotoxic T lymphocyte activity (CTL) was detected in mice immunized with DNA encoding gp120 either alone or as fusion with MDC. Therefore, the potential for broad application of this approach lies in the induction of mucosal CTL and neutralizing antibodies to HIV-1 envelope, both key requirements for prevention of viral transmission and clearance of pathogenic HIV from mucosal reservoirs.