Cytokine Expression In Dendritic Cells Research Articles

Autoimmune regulator‑overexpressing dendritic cells induce T helper 1 and T helper 17 cells by upregulating cytokine expression.

The autoimmune regulator (Aire) protein is a transcriptional activator that is essential in central immune tolerance, as it regulates the ectopic expression of many tissue‑restricted antigens in medullary thymic epithelial cells. Aire expression has also been described in hematopoietic cells, such as monocytes/macrophages and dendritic cells (DCs), in the peripheral immune system. However, the role of Aire expression in peripheral immune system cells, including DCs, remains to be elucidated. In the present study, the effects of secreted cytokines from Aire‑overexpressing DCs on cluster of differentiation (CD)4+ T cell subsets were investigated. The dendritic cell line, DC2.4, which overexpresses Aire, was co‑cultured with CD4+ T cells from splenocytes using Transwell inserts. The results indicate that Aire‑overexpressing cells induce T helper (Th)1 subsets by increasing interleukin (IL)‑12 expression, and induce Th17 subsets by upregulating IL‑6 and transforming growth factor (TGF)‑β production. In addition, it was observed that increased levels of phosphorylated extracellular signal‑regulated kinases and p38 upregulated the expression of cytokines in Aire‑overexpressing cells. These data suggest that Aire may have a role in inducing Th1 and Th17 differentiation by upregulating cytokine expression in DCs.

BET bromodomain inhibition suppresses graft-versus-host disease after allogeneic bone marrow transplantation in mice

AbstractAcute graft-versus-host disease (GVHD) is the major obstacle of allogeneic bone marrow transplantation (BMT). Bromodomain and extra-terminal (BET) protein inhibitors selectively block acetyl-binding pockets of the bromodomains and modulate histone acetylation. Here, we report that inhibition of BET bromodomain (BRD) proteins with I-BET151 alters cytokine expression in dendritic cells (DCs) and T cells, including surface costimulatory molecules, in vitro and in vivo cytokine secretion, and expansion. Mechanistic studies with I-BET151 and JQ1, another inhibitor, demonstrate that these effects could be from disruption of association between BRD4 and acetyl-310 RelA of nuclear factor kappa B. Short-term administration early during BMT reduced GVHD severity and improved mortality in two different allogeneic BMT models but retained sufficient graft-versus-tumor effect. Thus inhibiting BRD proteins may serve as a novel approach for preventing GVHD.

The Necroptosis Adaptor RIPK3 Promotes Injury-Induced Cytokine Expression and Tissue Repair

Programmed necrosis or necroptosis is an inflammatory form of cell death that critically requires the receptor-interacting protein kinase 3 (RIPK3). Here we showed that RIPK3 controls a separate, necrosis-independent pathway of inflammation by regulating cytokine expression in dendritic cells (DCs). Ripk3(-/-) bone-marrow-derived dendritic cells (BMDCs) were highly defective in lipopolysaccharide (LPS)-induced expression of inflammatory cytokines. These effects were caused by impaired NF-κB subunit RelB and p50 activation and by impaired caspase 1-mediated processing of interleukin-1β (IL-1β). This DC-specific function of RIPK3 was critical for injury-induced inflammation and tissue repair in response to dextran sodium sulfate (DSS). Ripk3(-/-) mice exhibited an impaired axis of injury-induced IL-1β, IL-23, and IL-22 cytokine cascade, which was partially corrected by adoptive transfer of wild-type DCs, but not Ripk3(-/-) DCs. These results reveal an unexpected function of RIPK3 in NF-κB activation, DC biology, innate inflammatory-cytokine expression, and injury-induced tissue repair.

Cathepsin K Is Involved in Development of Psoriasis-like Skin Lesions through TLR-Dependent Th17 Activation

Cathepsins (CTSs) are lysosomal cysteine proteases that play an important role in the turnover of intracellular proteins and extracellular proteins, such as the degradation of extracellular matrices and the processing of antigenic proteins. A CTS inhibitor, NC-2300, not only suppresses bone erosion by inhibition of cathepsin K (CTSK), but also ameliorates paw swelling at inflamed joints in adjuvant-induced arthritis in rats. It has been demonstrated that the amelioration of joint inflammation by NC-2300 is mediated by the downregulation of cytokine expression in dendritic cells, which are essential for Th17 activation. In this work, we studied the role for CTSs in the pathogenesis of psoriasis-like lesion in K5.Stat3C mice, a mouse model of psoriasis, in which Th17 contributes to lesion development similar to psoriasis. Psoriatic lesions expressed increased levels of Ctsk and Ctss mRNA compared with uninvolved skin and normal control skin. Similarly, the epidermis and dermis in K5.Stat3C mice demonstrated increased CTSK activities, which were sensitive to NC-2300. Topical treatment with NC-2300 significantly ameliorated 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like lesions in K5.Stat3C mice, and downregulated the expression of IL-12, IL-23, and Th17 cytokines. In vitro experiments revealed that TLR7 activation of bone marrow-derived myeloid dendritic cells led to increase in IL-23 at mRNA and protein levels, which were downregulated by NC-2300. These results suggest that CTSK plays a role in development of psoriatic lesions through TLR7-dependent Th17 polarization.

Categorization of traditional medicinal plants on inflammation-regulatory and anti-tumor activities by differenzial cytokine expression in dendritic cells

Traditional medicinal plants (TMP) are increasingly recognized for use in public health care throughout the world. However, systematic investigation of TMPs on specific and heath care-applicable immuno-regulatory activities is limited. Dendritic cells (DCs), a key type of professional antigen presenting cells are key mediators in human's immune systems. Therefore, DCs are considered by many as a viable pharmacological platform or target for evaluating TMP's immuno-regulatory activities. The objective of this study is to evaluate the regulatory activities of specific TMPs on cytokine regulation in DCs and anti-tumor activities in orthotopic mammary tumor model. Our results show that a number of extracts of test Taiwan specialty medicinal herbs exhibited an inhibitory activity on LPS-induced expression of IL-6 and IL-12 in mouse DCs. In addition, these herbal extracts were categorized into several functional sub-groups based on their capacities to regulate cytokine expression. In an orthotopic mammary tumor model, the extract of TMP1 effectively suppressed primary tumor growth. The extracts of both TMP1 and TMP2 suppressed mammary tumor metastasis, and the results were further confirmed by a mammary tumor resection model. Taken together, our results suggest that TMP1 and TMP2 may warrant further investigation for potential application as anti-tumor natural product agents.

Autophagy-Mediated Dendritic Cell Activation Is Essential for Innate Cytokine Production and APC Function with Respiratory Syncytial Virus Responses

The regulation of innate immune responses during viral infection is a crucial step to promote antiviral reactions. Recent studies have drawn attention to a strong relationship of pathogen-associated molecular pattern recognition with autophagy for activation of APC function. Our initial observations indicated that autophagosomes formed in response to respiratory syncytial virus (RSV) infection of dendritic cells (DC). To further investigate whether RSV-induced DC activation and innate cytokine production were associated with autophagy, we used several methods to block autophagosome formation. Using 3-MA, small interfering RNA inhibition of LC3, or Beclin(+/-) mouse-derived DC, studies established a relationship between RSV-induced autophagy and enhanced type I IFN, TNF, IL-6, and IL-12p40 expression. Moreover, autophagosome formation induced by starvation also promoted innate cytokine expression in DC. The induction of starvation-induced autophagy in combination with RSV infection synergistically enhanced DC cytokine expression that was blocked by an autophagy inhibitor. The latter synergistic responses were differentially altered in DC from MyD88(-/-) and TRIF(-/-) mice, supporting the concept of autophagy-mediated TLR signaling. In addition, blockade of autophagy in RSV-infected DC inhibited the maturation of DC as assessed by MHC class II and costimulatory molecule expression. Subsequently, we demonstrated that inhibition of autophagy in DC used to stimulate primary OVA-induced and secondary RSV-infected responses significantly attenuated cytokine production by CD4(+) T cells. Thus, these studies have outlined that autophagy in DC after RSV infection is a crucial mechanism for driving innate cytokine production, leading to altered acquired immune responses.

Immunostimulatory bacterial DNA sequences activate dendritic cells and promote priming and differentiation of CD8+ T cells.

CD8+ T lymphocytes producing high levels of interferon-gamma (IFN-gamma) and expressing antigen specific cytotoxic activity are effectively induced after plasmid DNA vaccination and mediate protection against several intracellular micro-organisms. Recent evidence suggests that the priming of CD8+ T-cell responses following DNA injection involves antigen presentation mediated by dendritic cells. Here, we show that bacterial DNA and synthetic oligonucleotides containing dinucleotide (CpG) motifs activate cytokine expression in dendritic cells and modulate in vivo CD8+ T-cell priming and differentiation.