IL-12 Production by Human Monocyte-Derived Dendritic Cells

Magnesium Ions Promote the Induction of Immunosuppressive Bone Microenvironment and Bone Repair through HIF-1α-TGF-β Axis in Dendritic Cells

The effect of immunoinflammation on bone repair during the recovery process of bone defects needs to be further explored. It is reported that Mg2+ can promote bone repair with immunoregulatory effect, but the underlying mechanism on adaptive immunity is still unclear. Here, by using chitosan and hyaluronic acid-coated Mg2+ (CSHA-Mg) in bone-deficient mice, it is shown that Mg2+ can inhibit the activation of CD4+ T cells and increase regulatory T cell formation by inducing immunosuppressive dendritic cells (imDCs). Mechanistically, Mg2+ initiates the activation of the MAPK signaling pathway through TRPM7 channels on DCs. This process subsequently induces the downstream HIF-1α expression, a transcription factor that amplifies TGF-β production and inhibits the effective T cell function. In vivo, knock-out of HIF-1α in DCs or using a HIF-1α inhibitor PX-478 reverses inhibition of bone inflammation and repair promotion upon Mg2+-treatment. Moreover, roxadustat, which stabilizes HIF-1α protein expression, can significantly promote immunosuppression and bone repair in synergism with CSHA-Mg. Thus, the findings identify a key mechanism for DCs and its HIF-1α-TGF-β axis in the induction of immunosuppressive bone microenvironment, providing potential targets for bone regeneration.

A role for whey acidic protein four-disulfide-core 12 (WFDC12) in the pathogenesis and development of psoriasis disease

Whey acidic protein four-disulfide core domain protein 12 (WFDC12) has been implicated in the pathogenesis of psoriasis but the specific molecular mechanism is not clearly defined. In this study, we found the expression of WFDC12 protein closely correlated with psoriasis. WFDC12 in keratinocyte might increase infiltration of Langerhans cells (LCs) and monocyte-derived dendritic cells (moDDCs), up-regulating the co-stimulation molecular CD40/CD86. Th1 cells in lymph nodes were higher in K14-WFDC12 transgenic psoiasis-like mice. Meanwhile, the mRNA of IL-12 and IFN-γ in the lesion skin was significantly increased in transgenic mice. Moreover, we found that the expression of the proteins that participated in the retinoic acid–related pathway and immune signaling pathway was more changed in the lesion skin of K14-WFDC12 transgenic psoriasis-like mice. Collectively, the results implied that WFDC12 might affect the activation of the retinoic acid signaling pathway and regulate the infiltration of DC cells in the skin lesions and lymph nodes, thereby inducing Th1 cells differentiation and increasing the secretion of IFN-γ to exacerbate psoriasis in mice.

Th1 regulatory events by infectious pathogens, herpes zoster and herpes simplex viruses: prospects for therapeutic options for atopic eczema

Infections caused by viral and bacterial pathogens are typically perceived as harmful, such as in cases of herpes zoster and herpes simplex virus infections. However, clinical observation of an improvement in atopic skin lesions upon herpes virus infection has been noted, particularly at the site of varicella and Kaposi’s varicelliform eruption. Th1 immune cells and cytokines, mobilized and induced for protection against infectious pathogens, are expected to improve Th2 dominant atopic symptoms. This study focuses on Th1 immunoregulatory events mediated by infectious pathogens, particularly herpes viruses. Immunoregulatory events induced by herpes viruses may have a potential therapeutic value for treating atopic eczema.

Long-Term Exposure to Inflammation Induces Differential Cytokine Patterns and Apoptosis in Dendritic Cells

The activation of dendritic cells (DCs) has profound implications and governs the control of adaptive immunity. However, long-term activation might drive exhaustion of immune cells and negatively affect functionality. Here, long-term vs. short-term exposure to bacterial lipopolysaccharide and interferon (IFN)γ was evaluated on human monocyte-derived DCs. Long-term activated DC1s began to undergo apoptosis concomitant with a profound TAM-receptor and efferocytosis-dependent induction of interleukin (IL)-10. Whereas, levels of IL-12p70 and IL-10 were positively correlated upon short-term activation, an inverse association occured upon long-term activation and, while short-term activated CD1a⁺ DCs were main producers of IL-12p70, CD1a⁻ DCs were the main fraction that underwent apoptosis and released IL-10 upon long-term activation. Moreover, pre-apoptotic long-term activated DCs were no longer able to activate alloreactive IFNγ-responsive T cells present in peripheral blood mononuclear cells from healthy volunteers. The IFNγ response was mediated by IL-12p70, as a strong reduction in IFNγ was observed following blockade with an IL-12p70 neutralizing antibody. Finally, multiplex analysis of DC supernatants revealed a particular pattern of proteins associated with apoptosis, cancer and chronic inflammation partly overlapping with gold standard DCs well-known for their inability to secrete IL-12p70. In conclusion, long-term activated DC1s significantly changed their profile toward a non-functional, tumor-promoting and anti-inflammatory phenotype.

Ap4A Regulates Directional Mobility and Antigen Presentation in Dendritic Cells

The significance of intracellular Ap₄A levels over immune activity of dendritic cells (DCs) has been studied in Nudt2^fl/fl/CD11c-cre mice. The transgenic mice have been generated by crossing floxed NUDT2 gene mice with DC marker CD11c recombinase (cre) mice. The DCs derived from these mice have higher levels of Ap₄A (≈30-fold) compared with those derived from Nudt2^+/+ mice. Interestingly, the elevated Ap₄A in DCs has led them to possess higher motility and lower directional variability. In addition, the DCs are able to enhance immune protection indicated by the higher cross-presentation of antigen and priming of CD8⁺ OT-I T cells. Overall, the study denotes prominent impact of Ap₄A over the functionality of DCs. The Nudt2^fl/fl/CD11c-cre mice could serve as a useful tool to study the influence of Ap₄A in the critical immune mechanisms of DCs.

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DCs of Nudt2^fl/fl/CD11c-cre mice exhibit low directional variability and high motility

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DCs elevate proliferation of OVA-specific T cell receptor transgenic CD8⁺ T cells

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The escalation of Ap₄A levels in DCs could enhance their immune protective activity

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Mice can serve as useful functional tool to study the role of Ap₄A in various cells

Periodontal disease immunology: 'double indemnity' in protecting the host

During the last two to three decades our understanding of the immunobiology of periodontal disease has increased exponentially, both with respect to the microbial agents triggering the disease process and the molecular mechanisms of the host engagement maintaining homeostasis or leading to collateral tissue damage. These foundational scientific findings have laid the groundwork for translating cell phenotype, receptor engagement, intracellular signaling pathways and effector functions into a 'picture' of the periodontium as the host responds to the 'danger signals' of the microbial ecology to maintain homeostasis or succumb to a disease process. These findings implicate the chronicity of the local response in attempting to manage the microbial challenge, creating a 'Double Indemnity' in some patients that does not 'insure' health for the periodontium. As importantly, in reflecting the title of this volume of Periodontology 2000, this review attempts to inform the community of how the science of periodontal immunology gestated, how continual probing of the biology of the disease has led to an evolution in our knowledge base and how more recent studies in the postgenomic era are revolutionizing our understanding of disease initiation, progression and resolution. Thus, there has been substantial progress in our understanding of the molecular mechanisms of host-bacteria interactions that result in the clinical presentation and outcomes of destructive periodontitis. The science has embarked from observations of variations in responses related to disease expression with a focus for utilization of the responses in diagnosis and therapeutic outcomes, to current investigations using cutting-edge fundamental biological processes to attempt to model the initiation and progression of soft- and hard-tissue destruction of the periodontium. As importantly, the next era in the immunobiology of periodontal disease will need to engage more sophisticated experimental designs for clinical studies to enable robust translation of basic biologic processes that are in action early in the transition from health to disease, those which stimulate microenvironmental changes that select for a more pathogenic microbial ecology and those that represent a rebalancing of the complex host responses and a resolution of inflammatory tissue destruction.

Intralesional delivery of dendritic cells engineered to express T-bet promotes protective type 1 immunity and the normalization of the tumor microenvironment

T-bet (Tbx21), a T-box transcription factor, has been previously identified as a master regulator of type 1 T cell polarization. We have also recently shown that the genetic engineering of human dendritic cells (DCs) to express human T-bet cDNA yields type 1-polarizing APCs in vitro (1). In the present study, murine CD11c(+) DCs were transduced with a recombinant adenovirus encoding full-length murine T-bets (DC.mTbets) and analyzed for their immunomodulatory functions in vitro and in vivo. Within the range of markers analyzed, DC.mTbets exhibited a control DC phenotype and were indistinguishable from control DCs in their ability to promote allogenic T cell proliferation in MLR in vitro. However, DC.mTbets were superior to control DCs in promoting Th1 and Tc1 responses in vitro via a mechanism requiring DC-T cell interaction or the close proximity of these two cell types and that can only partially be explained by the action of DC-elaborated IL-12p70. When injected into day 7 s.c. CMS4 sarcoma lesions growing in syngenic BALB/c mice, DC.mTbets dramatically slowed tumor progression (versus control DCs) and extended overall survival via a mechanism dependent on both CD4(+) and CD8(+) T cells and, to a lesser extent, asialoGM1(+) NK cells. DC.mTbet-based therapy also promoted superior tumor-specific Tc1 responses in the spleens and tumor-draining lymph nodes of treated animals, and within the tumor microenvironment it inhibited the accumulation of CD11b(+)Gr1(+) myeloid-derived suppressor cells and normalized CD31(+) vascular structures. These findings support the potential translational utility of DC.Tbets as a therapeutic modality in the cancer setting.

CD40 ligand-triggered human dendritic cells mount interleukin-23 responses that are further enhanced by danger signals

Interleukin (IL)-23 is a heterodimeric cytokine composed of the IL-23-specific subunit p19 and the p40 subunit which also constitutes part of IL-12. IL-23 propagates development of Th17 cells, a novel T cell subset which produces IL-17 but no interferon-gamma or IL-4. For both, IL-23 and IL-23-driven IL-17, a crucial role in autoimmune diseases such as experimental autoimmune encephalomyelitis, collagen-induced arthritis, and colitis is well accepted. Recent studies indicate that there is also a role for IL-23 and IL-17 in tumorigenesis, promoting tumor growth and vascularization, and affecting tumor incidence. We show that human CD14(+) peripheral blood monocyte-derived dendritic cells (DC), as used for clinical applications in anti-tumor immunization strategies, produce high amounts of IL-23. CD40-triggering of immature and mature DC but not of primary monocytes induced a rapid expression of high levels of IL-23, free p40, and minor levels of IL-12. Upon stimulation of DC subsets with a variety of different danger signals such as single stranded and double stranded RNA, bacterial components or viral infections, IL-23 expression pattern was analyzed. Interestingly, co-stimulation with CD40L enabled IL-23 expression by DC subsets towards danger signals to which they have been unresponsive upon single stimulation. Furthermore, we detected two novel splice variants of the IL-23-specific subunit p19 that could be associated with the regulation of IL-23 expression. Data presented here might have an impact on DC-based cancer vaccination strategies and contribute to a better understanding of the complex regulation of the heterodimeric cytokine IL-23.

CD40 ligation during dendritic cell maturation reduces cell death and prevents interleukin-10-induced regression to macrophage-like monocytes

Dendritic cells (DCs) have become popular candidates in cancer vaccination because of their crucial role in inducing T-cell responses. However, clinical studies greatly differ in their protocols for generating DCs and the efficacy in treating established tumors needs to be improved. We systematically analyzed DCs maturated by five different protocols for surface markers, the alloproliferative T-cell response, the DC survival after cytokine deprivation, the stability of surface markers under the influence of interleukin-10 (IL-10) and the DC cytokine secretion pattern. Monocyte-derived DCs were maturated by CD40-ligand (CD40-L), unmethylated cytosine-guanosine dinucleotides-oligodinucleotides (CpG-ODN), an inflammatory cytokine cocktail (ICC), a combination of ICC and CD40-L, or ICC, CD40-L and CpG-ODN. A high co-expression of DC maturation and costimulation markers was found after treatment with ICC plus CD40-L (69.3 +/- 9.6% CD83/CD80 double positive staining) and correlated with a significantly increased cell survival, a high expression of the antiapoptotic factor bcl-(XL), a stable CD83(high)/CD14(low) expression under the influence of IL-10, and a strong alloproliferative T-cell response. In conclusion, our data support the use of maturation protocols containing ICC plus CD40-L in order to generate highly mature, phenotypically stable, cell-death resistant, and T-cell stimulatory DCs for clinical application in cancer patients.

Toll-like receptors, Notch ligands, and cytokines drive the chronicity of lung inflammation

Current dogma supports the concept that the expression of a disease-inducing signature cytokine phenotype is important to the maintenance stage of chronic lung disorders. This cytokine phenotype has been characterized as a polarization toward type 2 cytokines, which are profibrotic and immunoregulatory. The biology of this latter activity could mechanistically explain pathogen-induced exacerbation of chronic lung inflammation, as a skewed cytokine profile in the lung alters dendritic cell function, activates fibroblasts, and facilitates a subsequent "second hit" by an infectious pathogen. In this setting, cytokine biology is also linked to Toll-like receptors (TLRs) in the maintenance of lung immunity, as the activity of this receptor-ligand system by both leukocytes and stromal cells is likely an important component of disease chronicity. The participation of dendritic cells via TLRs in chronic lung disease could facilitate communication circuits established between antigen-presenting cells and lymphocytes. Data suggest that TLR activation via myeloid differentiation factor 88 adaptor protein leads to the induction of a Notch ligand known as Delta-like-4 on dendritic cells that activate the Notch receptor on T cells, promoting a helper T-cell type 1 cytokine response. It is likely that the evolution of host defense signals designed to recognize patterns emitted from a hostile microbial environment may now be superimposed on adaptive immunity and provide the underpinning to support the maintenance of chronic lung disease.

Identification of HLA class I dependent immunogenic peptides from clonotypic TCRbeta expressed in cutaneous T-cell lymphoma

The clonotypic T-cell receptor (TCR) is a potential target antigen for specific immunotherapy of cutaneous T-cell lymphoma (CTCL). We identified T-cell epitopes from the rearranged TCR beta chain of the malignant T-cell population by the "reverse immunology" approach. Peptide-specific T-cell lines were generated against predicted epitopes and tested for the recognition of tumor cells and cells transfected with the full-length DNA coding for TCRV beta chain. Two peptides derived from the clonotypic TCRVbeta of a HLA-A2 positive patient could induce peptide-specific T cells from peripheral blood mononuclear cells of healthy donors and the patient as assessed by IFN-gamma ELISpot assay. Furthermore, the reactive CTLs efficiently recognized autologous Sézary tumor cells, as well as HLA-A2 positive 293 cells transfected with recombinant plasmid expressing the corresponding TCRVbeta29 protein. Similar results were obtained in a HLA-A3+ patient for TCRVbeta7-Jbeta2.7. In conclusion, our experiments show that the TCR beta chain harbors epitopes suitable as targets for specific vaccination which might be a promising approach for the specific immunotherapy of cutaneous T-cell lymphoma patients.

Soluble human LAG-3 molecule amplifies the in vitro generation of type 1 tumor-specific immunity

The adjuvant activities of the human lymphocyte activation gene-3 (LAG-3) molecule have been evaluated in a human setting by investigating the ability of a soluble recombinant human LAG-3 protein (hLAG-3Ig) to enhance the in vitro induction of viral- and tumor-specific CTLs. We found that soluble human LAG-3 significantly sustained the generation and expansion of influenza matrix protein Melan-A/MART-1 and survivin-specific CD8+ T lymphocytes in peripheral blood mononuclear cells (PBMC) of both cancer patients and healthy donors, showing its ability to boost CD8+ T-cell memory response or to prime naive T cells in vitro. The peptide-specific T cells generated in the presence of hLAG-3Ig were endowed with cytotoxic activity and enhanced release of type 1 cytotoxic T (Tc1) cytokines and were able to recognize tumor cells expressing their nominal antigen. Phenotype and cytokine/chemokines produced by antigen-presenting cells (APC) of PBMCs exposed in vitro for 2 days to peptide and hLAG-3Ig indicate that the LAG-3-mediated adjuvant effect may depend on a direct activation of circulating APCs. Our data revealed the activity of hLAG-3Ig in inducing tumor-associated, antigen-specific CD8+ T-cell responses in a human setting and strongly support the conclusion that this recombinant protein is a potential candidate adjuvant for cancer vaccines.

T Cell-Independent, TLR-Induced IL-12p70 Production in Primary Human Monocytes

IL-12p70 is a key cytokine for the induction of Th1 immune responses. IL-12p70 production in myeloid cells is thought to be strictly controlled by T cell help. In this work we demonstrate that primary human monocytes can produce IL-12p70 in the absence of T cell help. We show that human monocytes express TLR4 and TLR8 but lack TLR3 and TLR7 even after preincubation with type I IFN. Simultaneous stimulation of TLR4 and TLR8 induced IL-12p70 in primary human monocytes. IL-12p70 production in peripheral blood myeloid dendritic cells required combined stimulation of TLR7/8 ligands together with TLR4 or with TLR3 ligands. In the presence of T cell-derived IL-4, but not IFN-gamma, stimulation with TLR7/8 ligands was sufficient to stimulate IL-12p70 production. In monocytes, type I IFN was required but not sufficient to costimulate IL-12p70 induction by TLR8 ligation. Furthermore, TLR8 ligation inhibited LPS-induced IL-10 in monocytes, and LPS alone gained the ability to stimulate IL-12p70 in monocytes when the IL-10 receptor was blocked. Together, these results demonstrate that monocytes are licensed to synthesize IL-12p70 through type I IFN provided via the Toll/IL-1R domain-containing adaptor inducing IFN-beta pathway and the inhibition of IL-10, both provided by combined stimulation with TLR4 and TLR8 ligands, triggering a potent Th1 response before T cell help is established.