Induction of IL-10 producing CD4+ T cells with regulatory activities by stimulation with IL-10 gene-modified bone marrow derived dendritic cells

The role of dendritic cells in the immunomodulation to implanted biomaterials

Considering the substantial role played by dendritic cells (DCs) in the immune system to bridge innate and adaptive immunity, studies on DC-mediated immunity toward biomaterials principally center on their adjuvant effects in facilitating the adaptive immunity of codelivered antigens. However, the effect of the intrinsic properties of biomaterials on dendritic cells has not been clarified. Recently, researchers have begun to investigate and found that biomaterials that are nonadjuvant could also regulate the immune function of DCs and thus affect subsequent tissue regeneration. In the case of proteins adsorbed onto biomaterial surfaces, their intrinsic properties can direct their orientation and conformation, forming “biomaterial-associated molecular patterns (BAMPs)”. Thus, in this review, we focused on the intrinsic physiochemical properties of biomaterials in the absence of antigens that affect DC immune function and summarized the underlying signaling pathways. Moreover, we preliminarily clarified the specific composition of BAMPs and the interplay between some key molecules and DCs, such as heat shock proteins (HSPs) and high mobility group box 1 (HMGB1). This review provides a new direction for future biomaterial design, through which modulation of host immune responses is applicable to tissue engineering and immunotherapy.

Porcine-Stimulated Human Tr1 Cells Showed Enhanced Suppression in Xenoantigen Stimulation Response

Type 1 regulatory T (Tr1) cells play a fundamental role in maintaining and inducing immune tolerance. Our preliminary study demonstrated that an interleukin- (IL-) 10-mediated pathway is a possible regulatory mechanism underlying the xenoantigen-specific human Treg enhanced suppressive capacity. Here, we developed a feasible protocol for expanding IL-10-induced xenoantigen-specific human Tr1 cells in vitro which would be more efficient in transplantation immunotherapy efficiency. In this study, xenoantigen-specific Tr1 cells are generated from human naive CD4+ T cells expanded for two subsequent xenoantigen-stimulation cycles with recombinant human IL-10. The phenotype and suppressive capacity of xenoantigen-stimulated Tr1 cells are assessed, and the mechanism of their suppression is studied. Tr1 cells can be induced by porcine xenoantigen stimulation combined with IL-10, IL-2, and IL-15, displaying an increased expression of CD49b, CTLA-4, and LAG-3 without expressing Foxp3 which also showed an effector memory Treg phenotype and expressed high levels of CD39. After xenoantigen stimulation, the IL-10 and IL-5 gene expression in Tr1 cells increased, secreting more IL-10, and xenoantigen-stimulated Tr1 cells changed their T cell receptor (TCR) Vβ repertoire, increasing the expression of TCR Vβ2, TCR Vβ9, and TCR Vβ13. In a pig to human mixed lymphocyte reaction (MLR), xenoantigen-stimulated Tr1 cells displayed enhanced suppressive capacity via CD39 in a dose-dependent manner. Moreover, IL-5 could affect the proliferation of xenoantigen-specific Tr1 cells, but not their phenotypes' expression. This study provides a theory and feasible method for immune tolerance induction in clinical xenotransplantation.

Folate deficiency affects dendritic cell function and subsequent T helper cell differentiation

Insufficient folate status may be related to the increasing prevalence of immune- or inflammation-related chronic diseases. To investigate the effects of folate on immune regulation, we examined the impact of folate deficiency (FD) on dendritic cell (DC) maturation and function and, thus, T helper (Th) cells differentiation. First, bone marrow-derived DCs (BMDCs) were generated from BALB/c mice bone marrow cells cultured in folate-containing (F-BMDCs) or folate-deficient (FD-BMDCs) medium. FD-BMDC displayed more immature phenotype including reduced levels of major histocompatibility complex class II (MHC II), co-stimulatory molecules and characteristic of higher endocytic activity. FD-BMDC produced less IL-12p70 and proinflammatory cytokines in response to lipopolysaccharide. This aberrant DC maturation due to FD resulted in reduced BMDC-induced Th cell activity and lower IL-2, IFNγ, IL-13 and IL-10 productions. Further in vivo study confirmed significantly lower IFNγ and IL-10 productions by T cells and showed higher splenic naïve Th and lower memory T, effector T and regulatory T cell (Treg) percentages in mice fed with the FD diet for 13 weeks. To investigate the role of DCs on T cell activity, splenic DCs (spDC) from FD mice were cocultured with Th cells. The FD spDC had lower MHC II and CD80 expressions and subsequently impaired DC-induced Th differentiation, shown as decreased cytokine productions. This study demonstrated that folate deficiency impaired DC functions and, thus, Th differentiation and responses, suggesting that folate plays a crucial role in maintaining Th cells homeostasis.

Protection against Paracoccidioides brasiliensis infection in mice treated with modulated dendritic cells relies on inhibition of interleukin-10 production by CD8+ T cells

Paracoccidioidomycosis is a systemic infection prevalent in Latin American countries. Disease develops after inhalation of Paracoccidioides brasiliensis conidia followed by an improper immune activation by the host leucocytes. Dendritic cells (DCs) are antigen-presenting cells with the unique ability to direct the adaptive immune response by the time of activation of naive T cells. This study was conducted to test whether extracts of P. brasiliensis would induce maturation of DCs. We found that DCs treated with extracts acquired an inflammatory phenotype and upon adoptive transfer conferred protection to infection. Interestingly, interleukin-10 production by CD8(+) T cells was ablated following DC transfer. Further analyses showed that lymphocytes from infected mice were high producers of interleukin-10, with CD8(+) T cells being the main source. Blockage of cross-presentation to CD8(+) T cells by modulated DCs abolished the protective effect of adoptive transfer. Collectively, our data show that adoptive transfer of P. brasiliensis-modulated DCs is an interesting approach for the control of infection in paracoccidioidomycosis.

A B-1a cell subset induces Foxp3(-) T cells with regulatory activity through an IL-10-independent pathway

Regulatory T (Treg) cells play a critical role in the maintenance of tolerance. B-1a cells belong to a specific and functionally important B-cell subset that exerts its regulatory role through the production of IL-10. While IL-10 has been correlated with the induction of type 1 Treg (Tr1) cells or Tr1-like cells, whether IL-10-producing B-1a cells are able to induce Treg cells, especially the Tr1 lineage, is poorly understood. We have demonstrated that, similar to the reported B-2 cells, B-1a cells are able to convert naïve CD4(+)CD25(-) T cells into a subset of T cells with suppressive function, which we called 'Treg-of-B1a' cells. Treg-of-B1a cells do not express Foxp3, but upregulate the Treg markers OX40, programmed death 1 (PD-1), inducible costimulator (ICOS) and IL-10R. Moreover, Treg-of-B1a cells do not express Foxp3 and produce high levels of IFN-γ and IL-10, but minimal amounts of IL-4; therefore, they resemble Tr1 cells. However, utilizing IL-10(-/-) mice, we showed that IL-10 was not involved in the induction of Treg-of-B1a cells. On the contrary, CD86-mediated costimulation was essential for B-1a cells to drive the induction of Treg-of-B1a cells. Finally, we demonstrated that, in contrast to the Treg cells generated by B-2 cells that mediate contact-dependent suppression, Treg-of-B1a cells suppress through secreting soluble factors. While Tr1 cells mediate suppression mainly through IL-10 or TGF-β secretion, Treg-of-B1a cells mediate suppression through an IL-10- and TGF-β-independent pathway. Together, these findings suggest that B-1a cells induce a functionally and phenotypically distinct Treg population that is dissimilar to the reported Foxp3(+) Treg or Tr1 cells.

Protection to respiratory challenge of Brucella abortus strain 2308 in the lung

Brucella is amongst the top 5 causes of zoonotic disease worldwide. Infection is through ingestion, inhalation or contact exposure. Brucella is characterized as a class B pathogen by Centers of Disease Control and Prevention (CDC). Currently, there are no efficacious vaccines available in people. Currently available USDA approved vaccines for animals include B. abortus strain RB51 and B. melitensis Rev1. Protection is mediated by a strong innate and CD4 Th1, CD8 Tc1 immune response. If protective vaccines can be developed, disease in people and animals can be controlled. While strain RB51 protects in cattle, and against intraperitoneal challenge in mice, it does not protect against respiratory challenge. Therefore, we assessed the efficacy of strain RB51 combined with different TLR agonists, and O-side chain from LPS, to enhance protection against respiratory challenge with strain 2308. We hypothesized that TLR agonists and O-side chain would enhance protection. Strains RB51 with TLR2 agonist, RB51 with TLR4 agonist and strain 19 provided significant protection in the lung. Protection using strain RB51 with TLR agonists was associated with increased IgG2a and IgG1 in the (bronchoalveolar lavage) BAL and serum, and increased IgA (serum). Splenocytes from strain RB51 with TLR2 vaccinated mice up-regulated antigen specific interferon-gamma and TNF-alpha production. Vaccination and challenge resulted in significant increases in activated dendritic cells (DCs), and increased CD4 and CD8 cells in the BAL. Overall, this study demonstrates the ability of TLR agonists 2 and 4 to up-regulate strain RB51 mediated protection in the lung to respiratory challenge against strain 2308.

Nucleofection of a DNA vaccine into human monocyte-derived dendritic cells

An efficient method for delivering DNA vaccines into dendritic cells is considered to be of paramount importance. Electroporation-based technology (nucleofection) has gained increasingly popularity, but few reports focused on the possible functional consequences related to this method. In this study, the nucleofection technique was used to transfer the recombinant plasmid into hMoDCs for phenotype expression analysis and immunopotency detection. The results showed that the nucleofection of increasing concentrations of plasmid DNA decreased the viability of the hMoDCs. The welfare of nucleofected hMoDCs depended on the dosage of the plasmid and the plasmid's retention time within the cells. Accompanied by the process of nucleofection, it would bring some non-specific changes. The methodology reported here is suggestive of a feasible system for DNA vaccine transfer into hMoDCs with the caution of certain undesired effect.

Cytokine-conditioned dendritic cells induce humoral tolerance to protein therapy in mice

A major obstacle in the genetic therapy of inherited metabolic disease is host immune responses to the therapeutic protein. This is best exemplified by inhibitor formation in the protein therapy for hemophilia A. An approach to overcoming this is induction of immunological tolerance to the therapeutic protein. Tolerogenic dendritic cells (DCtols) have been reported to induce tolerance. In addition, cytokines such as interleukin (IL)-10 and transforming growth factor (TGF)-β(1) are known to induce tolerance. To model protein therapy, we used ovalbumin (OVA) as antigen in BALB/c mice and their transgenic derivative, DO11.10 mice. In this study we show that adoptive transfer of antigen-pulsed dendritic cells (DCs) treated with a combination of IL-10 and TGF-β(1) can suppress the antibody response in mice. Adoptive transfer of cytokine-conditioned DCs in preimmunized mice results in reduction of antibody response in the mice. Furthermore, the effect is antigen specific, as the recipient mice were able to mount a potent antibody response to the control antigen. Last, we show that TGF-β(1) and IL-10-conditioned DCs are able to inhibit anti-FVIII antibody responses in FVIII knockout (KO) mice. Analysis of the contribution of IL-10 and TGF-β(1) to the DCtol phenotype shows that IL-10 treatment of DCs is sufficient for inducing OVA-specific tolerance in BALB/c mice, but we observed a requirement for treatment with both human TGF-β(1) and human IL-10 to significantly inhibit anti-FVIII antibody responses in FVIII KO mice. This paper demonstrates that autologous cell therapy for antigen-targeted immune suppression may be developed to facilitate long-term therapy.

Cytokine gene-modulated dendritic cells protect against allergic airway inflammation by inducing IL-10(+)IFN-gamma(+)CD4(+) T cells

Asthma is characterized by allergen-induced airway inflammation orchestrated by Th2 cells. Dendritic cells (DCs) were found to efficiently prime naive T-helper cells. Thus, modification of DC function may be used as an ideal tool to treat allergic asthma by changing CD4(+) T-cell differentiation or suppressing Th2 development. In this study, we examined whether a DC-based vaccine can be applied to DCs modified with interleukin (IL)-10- and IL-12-expressing adenoviruses to prevent ovalbumin (OVA)-induced asthma in mice. Herein, we show that these modified DCs efficiently moderated the characteristics of asthma, including expressions of OVA-specific antibodies, airway hyperresponsiveness, eosinophilic airway inflammation, and Th2 cytokines production. Additionally, IL-10 and IL-12 gene-modified DCs enhanced the development of both T-helper type 1 (Th1) and IL-10(+)IFN-gamma(+) (interferon-gamma) double-positive T cells in vivo. In vitro-generated OVA-specific IL-10(+)IFN-gamma(+)CD4(+) T cells inhibited the proliferation of naive CD4(+) T cells, and this suppressive effect was a cell contact-dependent mechanism. Furthermore, we showed that combined cytokine-modulated DCs could alleviate established allergic airway inflammation. Taken together, these results suggest that IL-10 and IL-12 gene-modulated DCs are effective in suppressing asthmatic airway inflammation through both immune deviation and immune suppression and are a potential therapeutic approach for asthma.

Administration of polysaccharides from Antrodia camphorata modulates dendritic cell function and alleviates allergen-induced T helper type 2 responses in a mouse model of asthma

Asthma is a chronic disease characterized by airway inflammation caused by the dysregulated production of cytokines secreted by allergen-specific type 2 T helper (Th2) cells. Antrodia camphorata is a commonly used fungus in Asian folk medicine, and A. camphorata polysaccharides are reported to possess anti-cancer activities. In this study, the immunomodulatory effects of purified fractionated polysaccharides (GF2) from A. camphorata on dendritic cells (DCs) and their potential preventive effects against ovalbumin (OVA) -induced asthma were investigated. In the presence of GF2, lipopolysaccharide (LPS) -activated DCs exhibited up-regulated expression of major histocompatibility complex (MHC) class II and co-stimulatory molecules, as well as enhanced interleukin-10 (IL-10) and IL-12 production. GF2 treatment on LPS-activated DCs suppressed naïve CD4(+) T-cell proliferation and Th2 cell polarization with IL-10 production in an allogeneic mixed lymphocyte reaction. In animal experiments, a high dose of GF2 efficiently reduced expression levels of OVA-specific immunoglobulin G1 (IgG1) and IgE. However, lower doses of GF2 significantly enhanced OVA-specific IgG2a production. Our data also showed that administration of GF2 dose-dependently inhibited the development of airway hyperresponsiveness, airway eosinophilia and Th2 responses. OVA-specific CD4(+) T cells from higher doses of GF2-treated mice had significantly lower proliferative capacities compared with control mice. Moreover, treatment with GF2 significantly increased the high levels of IL-10 and low levels of interferon-gamma produced by T cells. Taken together, these data indicate that administration of A. camphorata polysaccharides (GF2) may have therapeutic potential when used as an adjuvant for the immunomodulatory treatment of allergic asthma.

Sialoadhesin-positive macrophages bind regulatory T cells, negatively controlling their expansion and autoimmune disease progression

An important regulatory suppressive function in autoimmune and other inflammatory processes has been ascribed to CD4(+)Foxp3(+) regulatory T cells (Tregs), which requires direct cell-cell communication between Tregs, effector T cells, and APCs. However, the molecular basis for these interactions has not yet been clarified. We show here that sialoadhesin (Sn), the prototype of the siglec family of sialic acid-binding transmembrane proteins, expressed by resident and activated tissue-infiltrating macrophages, directly binds to Tregs, negatively regulating their expansion in an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). In this model, macrophages infiltrate the CNS exhibiting tissue-destructing and demyelinating activity, leading to MS-like symptoms. We show here that severity of EAE symptoms is reduced in Sn knockout (KO) mice compared with wild-type littermates due to an up-regulation of CD4(+)Foxp3(+) Treg lymphocytes. Through the use of a Sn fusion protein, Tregs were shown to express substantial amounts of Sn ligand on their cell surface, and direct interaction of Sn(+) macrophages with Tregs specifically inhibited Treg but not effector T lymphocyte proliferation. Conversely, blocking of Sn on macrophages by Sn-specific Abs resulted in elevated proliferation of Tregs. Data indicate that Sn(+) macrophages regulate Treg homeostasis which subsequently influences EAE progression. We propose a new direct cell-cell interaction-based mechanism regulating the expansion of the Tregs during the immune response, representing a "dialogue" between Sn(+) macrophages and Sn-accessible sialic acid residues on Treg lymphocytes.