Jak3 is involved in dendritic cell maturation and CCR7-dependent migration

Tofacitinib downregulates JAK1 and JAK3 on human intestinal monocytes and macrophages without affecting dendritic cells phenotype or function

Background

Ulcerative colitis (UC) is an inflammatory disorder of the gastrointestinal tract. Although Tofacitinib, which inhibits the JAK1 and JAK3 signalling pathway, is approved to treat patients with UC, its specific mechanism of action remain elusive. Given the central role that conventional dendritic cells (cDC) elicit in gut homeostasis, we hypothesised that Tofacitinib acts modulating cDC function in UC.

Methods

Human biopsies were obtained from colon of controls, and patients with UC (active and quiescent). Lamina propria mononuclear cells (LPMC) were ex-vivo cultured in the presence/absence of Tofacitinib. The specific effect elicited over human intestinal cDC, monocytes and macrophages was assessed by flow cytometry. cDC were also enriched following Tofacitinib conditioning in order to assess its effect over naïve T-cells.

Results

Several human intestinal cDC, monocyte and macrophage subsets can be found in the human colon, with these cells being more similar between controls and patients with qUC referred to patients with aUC. Following ex-vivo culture, Tofacitinib downregulated JAK1 expression on intestinal monocytes from patients with both active and quiescent UC. As for macrophages, JAK1 was decreased on patients with active UC while JAK was downregulated on macrophages from patients with quiescent disease. Tofacitinib did not modulate the phenotype or function of human intestinal cDC.

Conclussion

Tofacitinib does not modulate the phenotype and function of human intestinal cDC in UC. On the contrary, it displays a differential capacity to modulate intestinal monocyte and macrophage phenotype. Future studies should address whether it also translates into a differential function of these cells.

Multimodal control of dendritic cell functions by nociceptors

It is known that interactions between nociceptors and dendritic cells (DCs) can modulate immune responses in barrier tissues. However, our understanding of the underlying communication frameworks remains rudimentary. Here, we show that nociceptors control DCs in three molecularly distinct ways. First, nociceptors release the calcitonin gene-related peptide that imparts a distinct transcriptional profile on steady-state DCs characterized by expression of pro-interleukin-1β and other genes implicated in DC sentinel functions. Second, nociceptor activation induces contact-dependent calcium fluxes and membrane depolarization in DCs and enhances their production of proinflammatory cytokines when stimulated. Finally, nociceptor-derived chemokine CCL2 contributes to the orchestration of DC-dependent local inflammation and the induction of adaptive responses against skin-acquired antigens. Thus, the combined actions of nociceptor-derived chemokines, neuropeptides, and electrical activity fine-tune DC responses in barrier tissues.

High Circulating Levels of the Homeostatic Chemokines CCL19 and CCL21 Predict Mortality and Disease Severity in COVID-19

BACKGROUND

Immune dysregulation is a major factor in the development of severe coronavirus disease 2019 (COVID-19). The homeostatic chemokines CCL19 and CCL21 have been implicated as mediators of tissue inflammation, but data on their regulation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is limited. We thus investigated the levels of these chemokines in COVID-19 patients.

METHODS

Serial blood samples were obtained from patients hospitalized with COVID-19 (n = 414). Circulating CCL19 and CCL21 levels during hospitalization and 3-month follow-up were analyzed. In vitro assays and analysis of RNAseq data from public repositories were performed to further explore possible regulatory mechanisms.

RESULTS

A consistent increase in circulating levels of CCL19 and CCL21 was observed, with high levels correlating with disease severity measures, including respiratory failure, need for intensive care, and 60-day all-cause mortality. High levels of CCL21 at admission were associated with persisting impairment of pulmonary function at the 3-month follow-up.

CONCLUSIONS

Our findings highlight CCL19 and CCL21 as markers of immune dysregulation in COVID-19. This may reflect aberrant regulation triggered by tissue inflammation, as observed in other chronic inflammatory and autoimmune conditions. Determination of the source and regulation of these chemokines and their effects on lung tissue is warranted to further clarify their role in COVID-19.

CLINICAL TRIALS REGISTRATION

NCT04321616 and NCT04381819.

Autologous dendritic cells pulsed with allogeneic tumour cell lysate induce tumour-reactive T-cell responses in patients with pancreatic cancer: A phase I study

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its poor prognosis even after curative resection. Responses to immunotherapy are rare and related to inadequate T-cell priming. We previously demonstrated the potency of allogeneic lysate-dendritic cell (DC) vaccination in a preclinical model. Here we translate this concept to patients.

METHODS

In this phase I study, patients with resected PDAC were included when they demonstrated no radiologic signs of recurrence after standard-of-care treatment. Allogeneic tumour lysate-loaded autologous monocyte-derived DCs were injected at weeks 0, 2, 4 and at months 3 and 6. Objectives are feasibility, safety and immunogenicity of allogeneic tumour-DCs. The presence of tumour antigens shared between the vaccine and patient tumours was investigated. Immunological analyses were performed on peripheral blood, skin and tumour.

RESULTS

Ten patients were included. DC production and administration were successful. All patients experienced a grade 1 injection-site and infusion-related reaction. Two patients experienced a grade 2 fever and 1 patient experienced a grade 3 dyspnoea. No vaccine-related serious adverse events were observed. Shared tumour antigens were found between the vaccine and patient tumours. All evaluated patients displayed a vaccine-induced response indicated by increased frequencies of Ki67+ and activated PD-1+ circulating T-cells. In addition, treatment-induced T-cell reactivity to autologous tumour of study patients was detected. Seven out of ten patients have not experienced disease recurrence or progression at a median follow-up of 25 months (15-32 months).

CONCLUSION

Allogeneic tumour lysate-DC treatment is feasible, safe and induces immune reactivity to PDAC expressed antigens.

Immune cells surveil aberrantly sialylated O-glycans on megakaryocytes to regulate platelet count

Immune thrombocytopenia (ITP) is a platelet disorder. Pediatric and adult ITP have been associated with sialic acid alterations, but the pathophysiology of ITP remains elusive, and ITP is often a diagnosis of exclusion. Our analysis of pediatric ITP plasma samples showed increased anti-Thomsen-Friedenreich antigen (TF antigen) antibody representation, suggesting increased exposure of the typically sialylated and cryptic TF antigen in these patients. The O-glycan sialyltransferase St3gal1 adds sialic acid specifically on the TF antigen. To understand if TF antigen exposure associates with thrombocytopenia, we generated a mouse model with targeted deletion of St3gal1 in megakaryocytes (MK) (St3gal1MK-/-). TF antigen exposure was restricted to MKs and resulted in thrombocytopenia. Deletion of Jak3 in St3gal1MK-/- mice normalized platelet counts implicating involvement of immune cells. Interferon-producing Siglec H-positive bone marrow (BM) immune cells engaged with O-glycan sialic acid moieties to regulate type I interferon secretion and platelet release (thrombopoiesis), as evidenced by partially normalized platelet count following inhibition of interferon and Siglec H receptors. Single-cell RNA-sequencing determined that TF antigen exposure by MKs primed St3gal1MK-/- BM immune cells to release type I interferon. Single-cell RNA-sequencing further revealed a new population of immune cells with a plasmacytoid dendritic cell-like signature and concomitant upregulation of the immunoglobulin rearrangement gene transcripts Igkc and Ighm, suggesting additional immune regulatory mechanisms. Thus, aberrant TF antigen moieties, often found in pathological conditions, regulate immune cells and thrombopoiesis in the BM, leading to reduced platelet count.

Protein kinase 2 (CK2): a potential regulator of immune cell development and function in cancer

Protein kinase CK2, formally known as casein kinase II, is ubiquitously expressed and highly conserved serine/threonine or tyrosine kinase enzyme that regulates diverse signaling pathways responsible for cellular processes (i.e., cell proliferation and apoptosis) via interactions with over 500 known substrates. The enzyme's physiological interactions and cellular functions have been widely studied, most notably in the blood and solid malignancies. CK2 has intrinsic role in carcinogenesis as overexpression of CK2 subunits (α, α`, and β) and deregulation of its activity have been linked to various forms of cancers. CK2 also has extrinsic role in cancer stroma or in the tumor microenvironment (TME) including the immune cells. However, very few research studies have focused on extrinsic role of CK2 in regulating immune responses as a therapeutic alternative for cancer. The following review discusses CK2's regulation of key signaling events [Nuclear factor kappa B (NF-κB), Janus kinase/signal transducer and activators of transcription (JAK/STAT), Hypoxia inducible factor-1alpha (HIF-1α), Cyclooygenase-2 (COX-2), Extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK), Notch, Protein kinase B/AKT, Ikaros and Wnt] that can influence the development and function of immune cells in cancer. Potential clinical trials using potent CK2 inhibitors will facilitate and improve the treatment of human malignancies.

Human genetic dissection of papillomavirus-driven diseases: new insight into their pathogenesis

Human papillomaviruses (HPVs) infect mucosal or cutaneous stratified epithelia. There are 5 genera and more than 200 types of HPV, each with a specific tropism and virulence. HPV infections are typically asymptomatic or result in benign tumors, which may be disseminated or persistent in rare cases, but a few oncogenic HPVs can cause cancers. This review deals with the human genetic and immunological basis of interindividual clinical variability in the course of HPV infections of the skin and mucosae. Typical epidermodysplasia verruciformis (EV) is characterized by β-HPV-driven flat wart-like and pityriasis-like cutaneous lesions and non-melanoma skin cancers in patients with inborn errors of EVER1-EVER2-CIB1-dependent skin-intrinsic immunity. Atypical EV is associated with other infectious diseases in patients with inborn errors of T cells. Severe cutaneous or anogenital warts, including anogenital cancers, are also driven by certain α-, γ-, μ or ν-HPVs in patients with inborn errors of T lymphocytes and antigen-presenting cells. The genetic basis of HPV diseases at other mucosal sites, such as oral multifocal epithelial hyperplasia or juvenile recurrent respiratory papillomatosis (JRRP), remains poorly understood. The human genetic dissection of HPV-driven lesions will clarify the molecular and cellular basis of protective immunity to HPVs, and should lead to novel diagnostic, preventive, and curative approaches in patients.

Environmental cues received during development shape dendritic cell responses later in life

Environmental signals mediated via the aryl hydrocarbon receptor (AHR) shape the developing immune system and influence immune function. Developmental exposure to AHR binding chemicals causes persistent changes in CD4+ and CD8+ T cell responses later in life, including dampened clonal expansion and differentiation during influenza A virus (IAV) infection. Naïve T cells require activation by dendritic cells (DCs), and AHR ligands modulate the function of DCs from adult organisms. Yet, the consequences of developmental AHR activation by exogenous ligands on DCs later in life has not been examined. We report here that early life activation of AHR durably reduces the ability of DC to activate naïve IAV-specific CD8+ T cells; however, activation of naïve CD4+ T cells was not impaired. Also, DCs from developmentally exposed offspring migrated more poorly than DCs from control dams in both in vivo and ex vivo assessments of DC migration. Conditional knockout mice, which lack Ahr in CD11c lineage cells, suggest that dampened DC emigration is intrinsic to DCs. Yet, levels of chemokine receptor 7 (CCR7), a key regulator of DC trafficking, were generally unaffected. Gene expression analyses reveal changes in Lrp1, Itgam, and Fcgr1 expression, and point to alterations in genes that regulate DC migration and antigen processing and presentation as being among pathways disrupted by inappropriate AHR signaling during development. These studies establish that AHR activation during development causes long-lasting changes to DCs, and provide new information regarding how early life environmental cues shape immune function later in life.

Human dendritic cell immunodeficiencies

The critical functions of dendritic cells (DCs) in immunity and tolerance have been demonstrated in many animal models but their non-redundant roles in humans are more difficult to probe. Human primary immunodeficiency (PID), resulting from single gene mutations, may result in DC deficiency or dysfunction. This relatively recent recognition illuminates the in vivo role of human DCs and the pathophysiology of the associated clinical syndromes. In this review, the development and function of DCs as established in murine models and human in vitro systems, discussed. This forms the basis of predicting the effects of DC deficiency in vivo and understanding the consequences of specific mutations on DC development and function. DC deficiency syndromes are associated with heterozygous GATA2 mutation, bi-allelic and heterozygous IRF8 mutation and heterozygous IKZF1 mutation. The intricate involvement of DCs in the balance between immunity and tolerance is leading to increased recognition of their involvement in a number of other immunodeficiencies and autoimmune conditions. Owing to the precise control of transcription factor gene expression by super-enhancer elements, phenotypic anomalies are relatively commonly caused by heterozygous mutations.

Tolerogenic dendritic cells induced by BD750 ameliorate proinflammatory T cell responses and experimental autoimmune encephalitis in mice

BD750, a novel JAK3/STAT5 inhibitor, can inhibit T cell proliferation. This study aims to evaluate whether BD750 can induce tolerogenic dendritic cells (tolDC) and their function in experimental autoimmune encephalitis (EAE) in mice. Following BD750 treatment, LPS-induced maturation of DC, allogeneic T cell proliferation, Th1 and Th17 cell functional differentiation, the STAT5 and AKT activation were determined. The effect of tolDC loaded with antigen peptide on the development and severity of EAE and their splenic Th1 and Th17 cell responses were determined. In comparison with LPS-induced mature DC (mDC), BD750 treatment induced tolDC with lower expression levels of costimulatory molecules and pro-inflammatory cytokines and lower levels of STAT5 phosphorylation. TolDC inhibited allogeneic T cell proliferation and reduced Th1 and Th17 responses. Adoptive transfer of tolDC loaded with MOG35-55 inhibited the development and severity of EAE in mice, accompanied by reduced numbers of inflammatory infiltrates and decreased levels of demyelination in the spinal cord tissues of mice. In addition, treatment with tolDC loaded with antigen peptide also significantly reduced the frequency of splenic Th1 and Th17 cells in EAE mice. The effects of tolDC were similar to that of the JAK/STAT inhibitor, CP690550-treated DC. In conclusion, treatment with BD750 induced tolDC that inhibited pro-inflammatory T cell immunity in vitro and in vivo. BD750 and tolDC may be valuable for development of new therapies for EAE and other autoimmune diseases.

Jak3 is involved in CCR7-dependent migration and invasion in metastatic squamous cell carcinoma of the head and neck

Patients with cervical lymph node metastasis in squamous cell carcinoma of the head and neck (SCCHN) exhibit a poor prognosis and low 5-year survival rate. It has been proven that chemokine receptor 7 (CCR7) promotes cellular migration and invasion in metastatic SCCHN. In the present study, the metastatic SCCHN PCI-37B cell line was utilized to explore the role of Janus activated kinase-3 (Jak3) in the CCR7-mediated signaling pathway in metastatic SCCHN cells. It was observed that phospho-Jak3 was expressed in SCCHN tissues. In addition, when the PCI-37B cells were analyzed in response to chemokine ligand 19 (CCL19), the ligand of CCR7, at the indicated time points, the results of the present study demonstrated that CCR7 induced Jak3 activation, and inhibition of Jak3 activity using a specific inhibitor, ZM39923, significantly attenuated CCR7-induced Jak3 phosphorylation. Migration and invasion assays and immunofluorescence staining experiments demonstrated that CCL19 promoted cell migration, invasion and F-actin rearrangment in CCR7-expressing SCCHN cells partially due to the activation of the Jak3 signaling pathway. These results demonstrate that the Jak3 signaling pathway is important for the CCR7-induced malignant biological behavior of SCCHN cells.

Tolerogenic Dendritic Cells Generated with Tofacitinib Ameliorate Experimental Autoimmune Encephalomyelitis through Modulation of Th17/Treg Balance

It is well known that dendritic cells (DCs) play a pivotal role in triggering self-specific responses. Conversely, tolerogenic DCs (tolDCs), a specialized subset, induce tolerance and negatively regulate autoreactive responses. Tofacitinib, a Janus kinase inhibitor developed by Pfizer for treatment of rheumatoid arthritis, is probable to be a promising candidate for inducing tolDCs. The aims of this study were to evaluate the effectiveness of tolDCs induced by tofacitinib in a myelin oligodendrocyte glycoprotein- (MOG-) specific experimental autoimmune encephalomyelitis (EAE) model and to investigate their effects on Th17/Treg balance in the animal model of multiple sclerosis (MS). Our results revealed that tofacitinib-treated DCs maintained a steady semimature phenotype with a low level of proinflammatory cytokines and costimulatory molecules. DCs treated by tofacitinib also induced antigen-specific T cells hyporesponsiveness in a concentration-dependent manner. Upon intravenous injection into EAE mice, MOG pulsed tolDCs significantly dampened disease activity, and adoptive cell therapy (ACT) disturbed Th17/Treg balance with a remarkable decrease of Th1/Th17 cells and an increase in regulatory T cells (Tregs). Overall, DCs modified by tofacitinib exhibited a typical tolerogenic phenotype, and the antigen-specific tolDCs may represent a new avenue of research for the development of future clinical treatments for MS.

A Key Role for Inhibins in Dendritic Cell Maturation and Function

Inhibins are members of the TGFβ superfamily, which regulate many cellular processes including differentiation, proliferation, survival and apoptosis. Although initially described as hormones regulating the hypothalamus-pituitary-gonadal axis, based on their ability to antagonize Activins, our group has recently reported that they play a role in thymocyte differentiation and survival, as well as in thymic stromal cell maturation and nTreg generation. Here, we used Inhibin knock out mice (Inhα-/-) to investigate the role of Inhibins in peripheral dendritic cell maturation and function. We first demonstrated that LPS treated Inhα+/+ bone marrow derived dendritic cells (BMDC) were capable to produce significant levels of Inhibin A. Interestingly, Inhα-/- BMDC showed reduced MHCII and CD86 upregulation and increased PD-L1 expression in response to LPS compared to Inhα+/+, which correlated with reduced ability to induce proliferation of allogeneic T cells. The "semi-mature" phenotype displayed by Inhα-/- mBMDC correlated with increased levels of IL-10 and slightly decreased IL-6 production after LPS stimulation. In addition, Inhα-/- mBMDC showed impaired migration towards CCL19 and CCL21, assessed by in vitro chemotaxis and in vivo competitive homing experiments, despite their normal CCR7 expression. Furthermore, in vivo LPS-induced DC maturation was also diminished in Inhα-/- mice, specially within the LC (CD207+ CD11b+ CD103-) subpopulation. Finally, analysis of delayed type hypersensitivity responses in Inhα-/- mice, showed reduced ear swelling as a result of reduced cellular infiltration in the skin, correlating with impaired homing of CD207+ DCs to the draining lymph nodes. In summary, our data demonstrate for the first time that Inhibins play a key role in peripheral DC maturation and function, regulating the balance between immunity and tolerance.

Curcumin Suppressed Activation of Dendritic Cells via JAK/STAT/SOCS Signal in Mice with Experimental Colitis

Dendritic cells (DCs) play a pivotal role as initiators in the pathogenesis of inflammatory bowel disease and are regulated by the JAK/STAT/SOCS signaling pathway. As a potent anti-inflammatory compound, curcumin represents a viable treatment alternative or adjunctive therapy in the management of chronic inflammatory bowel disease (IBD). The mechanism of curcumin treated IBD on DCs is not completely understood. In the present study, we explored the mechanism of curcumin treated experimental colitis by observing activation of DCs via JAK/STAT/SOCS signaling pathway in colitis mice. Experimental colitis was induced by 2, 4, 6-trinitrobenzene sulfonic acid. After 7 days treatment with curcumin, its therapeutic effect was verified by decreased colonic weight, histological scores, and remitting pathological injury. Meanwhile, the levels of major histocompatibility complex class II and DC costimulatory molecules (CD83, CD28, B7-DC, CD40, CD40 L, and TLR2) were inhibited and followed the up-regulated levels of IL-4, IL-10, and IFN-γ, and down-regulated GM-CSF, IL-12p70, IL-15, IL-23, and TGF-β1. A key finding was that the phosphorylation of the three members (JAK2, STAT3, and STAT6) of the JAK/STAT/SOCS signaling pathway was inhibited, and the three downstream proteins (SOCS1, SOCS3, and PIAS3) from this pathway were highly expressed. In conclusion, curcumin suppressed the activation of DCs by modulating the JAK/STAT/SOCS signaling pathway to restore immunologic balance to effectively treat experimental colitis.

Common and biased signaling pathways of the chemokine receptor CCR7 elicited by its ligands CCL19 and CCL21 in leukocytes

Chemokines are pivotal regulators of cell migration during continuous immune surveillance, inflammation, homeostasis, and development. Chemokine binding to their 7-transmembrane domain, G-protein-coupled receptors causes conformational changes that elicit intracellular signaling pathways to acquire and maintain an asymmetric architectural organization and a polarized distribution of signaling molecules necessary for directional cell migration. Leukocytes rely on the interplay of chemokine-triggered migration modules to promote amoeboid-like locomotion. One of the most important chemokine receptors for adaptive immune cell migration is the CC-chemokine receptor CCR7. CCR7 and its ligands CCL19 and CCL21 control homing of T cells and dendritic cells to areas of the lymph nodes where T cell priming and the initiation of the adaptive immune response occur. Moreover, CCR7 signaling also contributes to T cell development in the thymus and to lymphorganogenesis. Although the CCR7-CCL19/CCL21 axis evolved to benefit the host, inappropriate regulation or use of these proteins can contribute or cause pathobiology of chronic inflammation, tumorigenesis, and metastasis, as well as autoimmune diseases. Therefore, it appears as the CCR7-CCL19/CCL21 axis is tightly regulated at numerous intersections. Here, we discuss the multiple regulatory mechanism of CCR7 signaling and its influence on CCR7 function. In particular, we focus on the functional diversity of the 2 CCR7 ligands, CCL19 and CCL21, as well as on their impact on biased signaling. The understanding of the molecular determinants of biased signaling and the multiple layers of CCR7 regulation holds the promise for potential future therapeutic intervention.

Topically Administered Janus-Kinase Inhibitors Tofacitinib and Oclacitinib Display Impressive Antipruritic and Anti-Inflammatory Responses in a Model of Allergic Dermatitis

The prevalence of allergic skin disorders has increased rapidly, and development of therapeutic agents to alleviate the symptoms are still needed. In this study, we orally or topically administered the Janus kinase (JAK) inhibitors, tofacitinib and oclacitinib, in a mouse model of dermatitis, and compared the efficacy to reduce the itch and inflammatory response. In vitro effects of JAK inhibitors on bone marrow-derived dendritic cells (BMDCs) were analyzed. For the allergic dermatitis model, female BALB/c mice were sensitized and challenged with toluene-2,4-diisocyanate (TDI). Each JAK inhibitor was orally or topically applied 30 minutes before and 4 hours after TDI challenge. After scratching bouts and ear thickness were measured, cytokines were determined in challenged skin and the cells of the draining lymph node were analyzed by means of flow cytometry. In vitro, both JAK inhibitors significantly inhibited cytokine production, migration, and maturation of BMDCs. Mice treated orally with JAK inhibitors showed a significant decrease in scratching behavior; however, ear thickness was not significantly reduced. In contrast, both scratching behavior and ear thickness in the topical treatment group were significantly reduced compared with the vehicle treatment group. However, cytokine production was differentially regulated by the JAK inhibitors, with some cytokines being significantly decreased and some being significantly increased. In conclusion, oral treatment with JAK inhibitors reduced itch behavior dramatically but had only little effect on the inflammatory response, whereas topical treatment improved both itch and inflammatory response. Although the JAK-inhibitory profile differs between both JAK inhibitors in vitro as well as in vivo, the effects have been comparable.

Immunogenicity of a bovine herpesvirus 1 glycoprotein D DNA vaccine complexed with bovine neutrophil beta-defensin 3

Protective efficacy against bovine herpesvirus 1 (BoHV-1) has been demonstrated to be induced by a plasmid encoding bovine neutrophil beta-defensin 3 (BNBD3) as a fusion construct with truncated glycoprotein D (tgD). However, in spite of the increased cell-mediated immune responses induced by this DNA vaccine, the clinical responses of BoHV-1-challenged cattle were not reduced over those observed in animals vaccinated with the plasmid encoding tgD alone; this might have been because the vaccine failed to improve humoral responses. We hypothesized that an alternative vaccine design strategy that utilized the DNA vaccine pMASIA-tgD as a complex with BNBD3 might improve humoral responses while maintaining robust Th1-type cell-mediated responses. C57BL/6 mice were vaccinated with pMASIA-tgD complexed with 0, 0.01875, 0.1875, or 1.875 nmol of a stable synthesized analog of BNBD3 (aBNBD3). The best results were seen in mice immunized with the vaccine composed of pMASIA-tgD complexed to 0.1875 nmol aBNBD3. In this group, humoral responses were improved, as evidenced by increased virus neutralization, tgD-specific early IgG1, and later IgG2a titers, while the strong cell-mediated immune responses, measured based on specific gamma interferon (IFN-γ)-secreting cells, were maintained relative to pMASIA-tgD. Modulation of the immune response might have been due in part to the effect of BNBD3 on dendritic cells (DCs). In vitro studies showed that murine bone marrow-derived DCs (BMDCs) pretreated with aBNBD3 were activated, as evidenced by CD11c downregulation, and were functionally mature, as shown by increased allostimulatory ability. Native, synthetic, and analog forms of BNBD3 were equally capable of inducing functional maturation of BMDCs.

A mechanistic role for leptin in human dendritic cell migration: differences between ileum and colon in health and Crohn's disease

Dendritic cells (DC) migrate to lymph nodes on expression of C-C motif chemokine receptor 7 (CCR7) and control immune activity. Leptin, an immunomodulatory adipokine, functions via leptin receptors, signaling via the long isoform of receptor, LepRb. Leptin promotes DC maturation and increases CCR7 expression on blood DC. Increased mesenteric fat and leptin occur early in Crohn's disease (CD), suggesting leptin-mediated change in intestinal CCR7 expression on DC as a pro-inflammatory mechanism. We have demonstrated CCR7 expression and capacity to migrate to its ligand macrophage inflammatory protein 3β in normal human ileal DC but not colonic or blood DC. In CD, functional CCR7 was expressed on DC from all sites. Only DC populations containing CCR7-expressing cells produced LepRb; in vitro exposure to leptin also increased expression of functional CCR7 in intestinal DC in a dose-dependent manner. In conclusion, leptin may regulate DC migration from gut, in homeostatic and inflammatory conditions, providing a link between mesenteric obesity and inflammation.

The JAK-inhibitor ruxolitinib impairs dendritic cell function in vitro and in vivo

The Janus kinase (JAK)-inhibitor ruxolitinib decreases constitutional symptoms and spleen size of myelofibrosis (MF) patients by mechanisms distinct from its anticlonal activity. Here we investigated whether ruxolitinib affects dendritic cell (DC) biology. The in vitro development of monocyte-derived DCs was almost completely blocked when the compound was added throughout the differentiation period. Furthermore, when applied solely during the final lipopolysaccharide-induced maturation step, ruxolitinib reduced DC activation as demonstrated by decreased interleukin-12 production and attenuated expression of activation markers. Ruxolitinib also impaired both in vitro and in vivo DC migration. Dysfunction of ruxolitinib-exposed DCs was further underlined by their impaired induction of allogeneic and antigen-specific T-cell responses. Ruxolitinib-treated mice immunized with ovalbumin (OVA)/CpG induced markedly reduced in vivo activation and proliferation of OVA-specific CD8⁺ T cells compared with vehicle-treated controls. Finally, using an adenoviral infection model, we show that ruxolitinib-exposed mice exhibit delayed adenoviral clearance. Our results demonstrate that ruxolitinib significantly affects DC differentiation and function leading to impaired T-cell activation. DC dysfunction may result in increased infection rates in ruxolitinib-treated patients. However, our findings may also explain the outstanding anti-inflammatory and immunomodulating activity of JAK inhibitors currently used in the treatment of MF and autoimmune diseases.

Co-transfection gene delivery of dendritic cells induced effective lymph node targeting and anti-tumor vaccination

PURPOSE

Successful genetically engineered Dendritic Cell (DC) can enhance DC's antigen presentation and lymph node migration. The present study aims to genetically engineer a DC using an efficient non-viral gene delivery vector to induce a highly efficient antigen presentation and lymph node targeting in vivo.

METHODS

Spermine-dextran (SD), a cationic polysaccharide vector, was used to prepare a gene delivery system for DC engineering. Transfection efficiency, nuclear trafficking, and safety of the SD/DNA complex were evaluated. A vaccine prepared by engineering DC with SD/gp100, a plasmid encoding melanoma-associated antigen, was injected subcutaneously into mice to evaluate the tumor suppression. The migration of the engineered DCs was also evaluated in vitro and in vivo.

RESULTS

SD/DNA complex has a better transfection behavior in vitro than commercially purchased reagents. The DC vaccine co-transfected with plasmid coding CCR7, a chemokine receptor essential for DC migration, and plasmid coding gp100 displayed superior tumor suppression than that with plasmid coding gp100 alone. Migration assay demonstrated that DC transfected with SD/CCR7 can promote DC migration capacity.

CONCLUSIONS

The study is the first to report the application of nonviral vector SD to co-transfect DC with gp100 and CCR7-coding plasmid to induce both the capacity of antigen presentation and lymph node targeting.

Cellular MRI as a suitable, sensitive non-invasive modality for correlating in vivo migratory efficiencies of different dendritic cell populations with subsequent immunological outcomes

The clinical application of dendritic cells (DC) as adjuvants in immunotherapies such as the cell-based cancer vaccine continues to gain interest. The overall efficacy of this emerging immunotherapy, however, remains low. Studies suggest the stage of maturation and activation of ex vivo-prepared DC immediately prior to patient administration is critical to subsequent DC migration in vivo, which ultimately affects overall vaccine efficacy. While it is possible to generate mature and activated DC ex vivo using various stimulatory cocktails, in the case of cancer patients, the qualitative and quantitative assessment of which DC stimulatory cocktail works most effectively to enhance subsequent DC migration in vivo is difficult. Thus, a non-invasive imaging modality capable of monitoring the real-time migration of DC in long-term studies is required. In this paper, we address whether cellular magnetic resonance imaging (MRI) is sufficiently sensitive to quantitatively detect differences in the migratory abilities of two different DC preparations: untreated (resting) versus ex vivo matured in a mouse model. In order to distinguish our ex vivo-generated DC of interest from surrounding tissues in magnetic resonance (MR) images, DC were labeled in vitro with the superparamagnetic iron oxide (SPIO) nanoparticle FeREX®. Characterization of DC phenotype and function following addition of a cytokine maturation cocktail and the toll-like receptor ligand CpG, both in the presence and in the absence of SPIO, were also carried out. Conventional histological techniques were used to verify the quantitative data obtained from MR images. This study provides important information relevant to tracking the in vivo migration of ex vivo-prepared and stimulated DC.

Adaptive immune responses mediated by natural killer cells

Adaptive immunity has traditionally been considered a unique feature of vertebrate physiology. Unlike innate immune responses, which remain essentially unchanged upon exposure to a recurrent challenge with the same stimulus, adaptive immune cells possess the ability to learn and remember. Thus, secondary adaptive responses to a previously encountered challenge are qualitatively and/or quantitatively distinct from those elicited by a primary encounter. Besides this capacity to acquire long-lived memory, the second cardinal feature of adaptive immunity is antigen specificity. It has been generally believed that only T and B cells can develop antigen-specific immunologic memory, because these lymphocytes uniquely express recombination-activating gene (RAG) proteins, which are necessary for somatic rearrangement of V(D)J gene segments to assemble diverse antigen-specific receptors. However, recent work has uncovered discrete subsets of murine natural killer (NK) cells capable of mediating long-lived, antigen-specific recall responses to a variety of hapten-based contact sensitizers. These NK cells appear to use distinct, RAG-independent mechanisms to generate antigen specificity. Murine NK cells have also recently been shown to develop memory upon viral infection. Here, we review recent evidence indicating that at least some NK cells are capable of mediating what appears to be adaptive immunity and discuss potential mechanisms that may contribute to RAG-independent generation of antigenic diversity and longevity.

CD4+ CD25+ regulatory T cells prevent type 1 diabetes preceded by dendritic cell-dominant invasive insulitis by affecting chemotaxis and local invasiveness of dendritic cells

Development of type 1 diabetes (T1D) is preceded by invasive insulitis. Although CD4(+)CD25(+) regulatory T cells (nTregs) induce tolerance that inhibits insulitis and T1D, the in vivo cellular mechanisms underlying this process remain largely unclear. Using an adoptive transfer model and noninvasive imaging-guided longitudinal analyses, we found nTreg depletion did not affect systemic trafficking and tissue localization of diabetogenic CD4(+) BDC2.5 T (BDC) cells in recipient mice prior to development of T1D. In addition, neither the initial expansion/activation of BDC cells nor the number of CD11c(+) or NK cells in islets and pancreatic lymph nodes were altered. Unexpectedly, our results showed nTreg depletion led to accelerated invasive insulitis dominated by CD11c(+) dendritic cells (ISL-DCs), not BDC cells, which stayed in the islet periphery. Compared with control mice, the phenotype of ISL-DCs and their ability to stimulate BDC cells did not change during invasive insulitis development. However, ISL-DCs from nTreg-deficient recipient mice showed increased in vitro migration toward CCL19 and CCL21. These results demonstrated invasive insulitis dominated by DCs, not CD4(+) T cells, preceded T1D onset in the absence of nTregs, and suggested a novel in vivo function of nTregs in T1D prevention by regulating local invasiveness of DCs into islets, at least partly, through regulation of DC chemotaxis toward CCL19/CCL21 produced by the islets.

Inhibition of chemokine-glycosaminoglycan interactions in donor tissue reduces mouse allograft vasculopathy and transplant rejection

BACKGROUND

Binding of chemokines to glycosaminoglycans (GAGs) is classically described as initiating inflammatory cell migration and creating tissue chemokine gradients that direct local leukocyte chemotaxis into damaged or transplanted tissues. While chemokine-receptor binding has been extensively studied during allograft transplantation, effects of glycosaminoglycan (GAG) interactions with chemokines on transplant longevity are less well known. Here we examine the impact of interrupting chemokine-GAG interactions and chemokine-receptor interactions, both locally and systemically, on vascular disease in allografts.

METHODOLOGY/PRINCIPAL FINDINGS

Analysis of GAG or CC chemokine receptor 2 (CCR2) deficiency were coupled with the infusion of viral chemokine modulating proteins (CMPs) in mouse aortic allograft transplants (n = 239 mice). Inflammatory cell invasion and neointimal hyperplasia were significantly reduced in N-deacetylase-N-sulfotransferase-1 (Ndst1(f/f)TekCre(+)) heparan sulfate (GAG)-deficient (Ndst1(-/-), p<0.044) and CCR2-deficient (Ccr2(-/-), p<0.04) donor transplants. Donor tissue GAG or CCR2 deficiency markedly reduced inflammation and vasculopathy, whereas recipient deficiencies did not. Treatment with three CMPs was also investigated; Poxviral M-T1 blocks CC chemokine receptor binding, M-T7 blocks C, CC, and CXC GAG binding, and herpesviral M3 binds receptor and GAG binding for all classes. M-T7 reduced intimal hyperplasia in wild type (WT) (Ccr2(+/+), p< or =0.003 and Ccr2(-/-), p

CONCLUSIONS/SIGNIFICANCE

Interruption of chemokine-GAG interactions, even in the absence of chemokine-receptor blockade, is a highly effective approach to reduction of allograft rejection, reducing vascular inflammation and prolonging allograft survival. Although chemokines direct both local and systemic cell migration, interruption of inherent chemokine responses in the donor tissue unexpectedly had a greater therapeutic impact on allograft vasculopathy.

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MESH Headings

• Animals
• Aorta/drug effects
• Aorta/pathology
• Aorta/transplantation
• Cell Movement/drug effects
• Cell Proliferation/drug effects
• Chemokines/metabolism
• Chemokines/pharmacology
• Disease Models, Animal
• Glycosaminoglycans/metabolism
• Graft Rejection/complications
• Graft Rejection/enzymology
• Graft Rejection/immunology
• Hyperplasia
• Inflammation/complications
• Inflammation/pathology
• Kidney Transplantation
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Receptors, CCR2/deficiency
• Receptors, CCR2/metabolism
• Sulfotransferases/deficiency
• Sulfotransferases/metabolism
• Survival Analysis
• Tissue Donors
• Transplantation, Homologous
• Tunica Intima/drug effects
• Tunica Intima/pathology
• Vascular Diseases/complications
• Vascular Diseases/enzymology
• Vascular Diseases/immunology
• Vascular Diseases/pathology
• Viral Proteins/pharmacology

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Grants

• RC1 HL100202 NHLBI NIH HHS
• 1RC1HL100202-01 NHLBI NIH HHS
• MOP 577578 CIHR

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Affiliation(s)

Erbin Dai Vascular Biology Research Group, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Li-Ying Liu Vascular Biology Research Group, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Hao Wang Departments of Medicine and Surgery, and Microbiology and Immunology, The University of Western Ontario, London, Ontario, Canada
Dana McIvor Departments of Medicine and Surgery, and Microbiology and Immunology, The University of Western Ontario, London, Ontario, Canada
Yun ming Sun Vascular Biology Research Group, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada Viron Therapeutics, Inc., London, Ontario, Canada
Colin Macaulay Viron Therapeutics, Inc., London, Ontario, Canada
Elaine King Viron Therapeutics, Inc., London, Ontario, Canada
Ganesh Munuswamy-Ramanujam Vascular Biology Research Group, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Mee Yong Bartee Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Jennifer Williams Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Jennifer Davids Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Israel Charo Gladstone Institute, San Francisco, California, United States of America
Grant McFadden Departments of Medicine and Surgery, and Microbiology and Immunology, The University of Western Ontario, London, Ontario, Canada Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America
Jeffrey D. Esko Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, United States of America
Alexandra R. Lucas Vascular Biology Research Group, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada Departments of Medicine and Surgery, and Microbiology and Immunology, The University of Western Ontario, London, Ontario, Canada Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, United States of America Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, United States of America

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