Autoimmunity through cytokine-induced dendritic cell activation

Recent Findings on Therapeutic Cancer Vaccines: An Updated Review

Cancer remains one of the global leading causes of death and various vaccines have been developed over the years against it, including cell-based, nucleic acid-based, and viral-based cancer vaccines. Although many vaccines have been effective in in vivo and clinical studies and some have been FDA-approved, there are major limitations to overcome: (1) developing one universal vaccine for a specific cancer is difficult, as tumors with different antigens are different for different individuals, (2) the tumor antigens may be similar to the body's own antigens, and (3) there is the possibility of cancer recurrence. Therefore, developing personalized cancer vaccines with the ability to distinguish between the tumor and the body's antigens is indispensable. This paper provides a comprehensive review of different types of cancer vaccines and highlights important factors necessary for developing efficient cancer vaccines. Moreover, the application of other technologies in cancer therapy is discussed. Finally, several insights and conclusions are presented, such as the possibility of using cold plasma and cancer stem cells in developing future cancer vaccines, to tackle the major limitations in the cancer vaccine developmental process.

Hypovitaminosis A Drives the Progression of Tubulointerstitial Lupus Nephritis through Potentiating Predisease Cellular Autoreactivity

Vitamin A (VA) deficiency (VAD) is observed in both humans and mice with lupus nephritis. However, whether VAD is a driving factor for accelerated progression of lupus nephritis is unclear. In this study, we investigated the effect of VAD on the progression of lupus nephritis in a lupus-prone mouse model, MRL/lpr. We initiated VAD either during gestation or after weaning to reveal a potential time-dependent effect. We found exacerbated lupus nephritis at ∼15 wk of age with both types of VAD that provoked tubulointerstitial nephritis leading to renal failure. This was concomitant with significantly higher mortality in all VAD mice. Importantly, restoration of VA levels after weaning reversed VAD-induced mortality. These results suggest VAD-driven acceleration of tubulointerstitial lupus nephritis. Mechanistically, at the earlier time point of 7 wk of age and before the onset of clinical lupus nephritis, continued VAD (from gestation until postweaning) enhanced plasma cell activation and augmented their autoantibody production, while also increasing the expansion of T lymphocytes that could promote plasma cell autoreactivity. Moreover, continued VAD increased the renal infiltration of plasmacytoid dendritic cells. VAD initiated after weaning, in contrast, showed modest effects on autoantibodies and renal plasmacytoid dendritic cells that were not statistically significant. Remarkably, analysis of gene expression in human kidney revealed that the retinoic acid pathway was decreased in the tubulointerstitial region of lupus nephritis, supporting our findings in MRL/lpr mice. Future studies will elucidate the underlying mechanisms of how VAD modulates cellular functions to exacerbate tubulointerstitial lupus nephritis.

Oral tolerance to prevent anti-drug antibody formation in protein replacement therapies

Protein based therapeutics have successfully improved the quality of life for patients of monogenic disorders like hemophilia, Pompe and Fabry disease. However, a significant proportion of patients develop immune responses towards intravenously infused therapeutic protein, which can complicate or neutralize treatment and compromise patient safety. Strategies aimed at circumventing immune responses following therapeutic protein infusion can greatly improve therapeutic efficacy. In recent years, antigen-based oral tolerance induction has shown promising results in the prevention and treatment of autoimmune diseases, food allergies and can prevent anti-drug antibody formation to protein replacement therapies. Oral tolerance exploits regulatory mechanisms that are initiated in the gut associated lymphoid tissue (GALT) to promote active suppression of orally ingested antigen. In this review, we outline general perceptions and current knowledge about the mechanisms of oral tolerance, including tissue specific sites of tolerance induction and the cells involved, with emphasis on antigen presenting cells and regulatory T cells. We define several factors, such as cytokines and metabolites that impact the stability and expansion potential of these immune modulatory cells. We highlight preclinical studies that have been performed to induce oral tolerance to therapeutic proteins or enzymes for single gene disorders, such as hemophilia or Pompe disease. These studies mainly utilize a transgenic plant-based system for oral delivery of antigen in conjugation with fusion protein technology that favors the prevention of antigen degradation in the stomach while enhancing uptake in the small intestine by antigen presenting cells and regulatory T cell induction, thereby promoting antigen specific systemic tolerance.

Conjunctival epithelial cells resist productive SARS-CoV-2 infection

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-κB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

Monitoring Immune Cell Function Through Optical Imaging: a Review Highlighting Transgenic Mouse Models

Transgenic mouse models have facilitated research of human diseases and validation of therapeutic approaches. Inclusion of optical reporter genes (fluorescent or bioluminescent genes) in the targeting vectors used to develop such models makes in vivo imaging of cellular and molecular events possible, from the microscale to the macroscale. In particular, transgenic mouse models expressing optical reporter genes allowed accurately distinguishing immune cell types from trafficking in vivo using intravital microscopy or whole-body optical imaging. Besides lineage tracing and trafficking of different subsets of immune cells, the ability to monitor the function of immune cells is of pivotal importance for investigating the effects of immunotherapies against cancer. Here, we introduce the reader to state-of-the-art approaches to develop transgenics, optical imaging techniques, and several notable examples of transgenic mouse models developed for immunology research by critically highlighting the models that allow the following of immune cell function.

[Pharmacological actions of anifrolumab (Saphnelo®) and clinical trial results as a treatment for systemic lupus erythematosus]

Systemic lupus erythematosus (SLE) is an autoimmune disease which causes damaging inflammation in multiple organs via the accumulation of immune complexes. SLE pathogenesis is associated with type I interferons (IFNs), which are central and reflective of disease activity in SLE. Even before clinical development of disease, genetic and environmental contributions to IFN production lead to abnormal innate and adaptive immune activation. Through the Janus kinase-signal transducer and activator of transcription signaling pathway, IFN play a central role in the immunopathogenicity of SLE. Thus, IFN-blocking therapy may be used to regulate inflammation in individuals with SLE. Food and Drug Administration (FDA)-approved anifrolumab (Saphnelo^®), which is a human IgG1κ monoclonal antibody that binds to subunit 1 of the type I interferon receptor with high specificity and affinity, was also approved for the treatment of adult patients with moderate to severe SLE who are receiving standard therapy by Pharmaceuticals and Medical Device Agency (PMDA), in Japan in September 2021; anifrolumab is administered as an intravenous infusion, 300 mg over a 30-minute period, every 4 weeks. In this article, we reviewed the actions of type I IFN and anifrolumab as a treatment for SLE.

Comparison of two routes of administration of a cationic liposome formulation for a prophylactic DC vaccination in a murine melanoma model

Dendritic cell (DC) vaccination can be achieved via straight loading of vaccine into DCs ex vivo or administration to DCs in vivo. However, there is no certain consensus on which approach is preferable, and each strategy has its advantages and disadvantages, which affect the efficacy and safety of vaccines. It will also be more complicated when a vaccine delivery system is included. In this study, the efficacy of ex vivo pulsed DC-based vaccine compared with in vivo subcutaneous administration of a cationic liposomes (CLs) formulation containing gp100 antigen (gp100-CLs) was evaluated in a murine melanoma model. In combination with an anti-PD-1 antibody, the ex vivo approach of gp100-CLs yielded a significant (P < 0.01) increase in the number of antigen-specific tumors infiltrated lymphocytes (TILs) with a significant upregulation of IFN-γ (P < 0.0001) and PD-1 (P < 0.0001) expression level. They also dampened the function of immunosuppressive regulatory T cells (Tregs) via significant downregulation of IL-10 and TGF-β (P < 0.0001) expression level compared to in vivo approach in the tumor microenvironment (TME). Furthermore, prophylactic immunization with gp100-CLs pulsed DCs ex vivo delayed tumor growth and induced the survival benefit over in vivo immunization. Collectively, the ex vivo DC-based vaccination pulsed with gp100 encapsulated in liposomes synergizes with anti-PD-1 antibody and represents a preferable approach against melanoma.

Type I Interferons in Systemic Autoimmune Diseases: Distinguishing Between Afferent and Efferent Functions for Precision Medicine and Individualized Treatment

A sustained increase in type I interferon (IFN-I) may accompany clinical manifestations and disease activity in systemic autoimmune diseases (SADs). Despite the very frequent presence of IFN-I in SADs, clinical manifestations are extremely varied between and within SADs. The present short review will address the following key questions associated with high IFN-I in SADs in the perspective of precision medicine. 1) What are the mechanisms leading to high IFN-I? 2) What are the predisposing conditions favoring high IFN-I production? 3) What is the role of IFN-I in the development of distinct clinical manifestations within SADs? 4) Would therapeutic strategies targeting IFN-I be helpful in controlling or even preventing SADs? In answering these questions, we will underlie areas of incertitude and the intertwined role of autoantibodies, immune complexes, and neutrophils.

Adipokine role in physiopathology of inflammatory and degenerative musculoskeletal diseases

We performed a systematic literature review to summarize the underlying pathogenic mechanisms by which adipokines influence rheumatological diseases and the resulting clinical manifestations. Increasing evidence display that numerous adipokines may significantly influence the development or clinical course of various rheumatological diseases. Despite the normal anti- or pro-inflammatory role of the cytokines, the serum level varies enormously in various rheumatological diseases. The expression of high levels of pro-inflammatory cytokines such as leptin or visfatin, respectively in systemic lupus erythematosus and in rheumatoid arthritis, represents a negative prognostic factor; other adipokines such as adiponectin, broadly known for their anti-inflammatory effects, showed a correlation with disease activity in rheumatoid arthritis. In the near future pro-inflammatory cytokines may represent a potential therapeutic target to restrain the severity of rheumatological diseases. Further studies on adipokines may provide important information on the pathogenesis of these diseases, which are not yet fully understood. The mechanisms by which adipokines induce, worsen, or suppress inflammatory and degenerative musculoskeletal pathologies and their clinical significance will be discussed in this review.

Context Is Key: Delineating the Unique Functions of IFNα and IFNβ in Disease

Type I interferons (IFNs) are critical effector cytokines of the immune system and were originally known for their important role in protecting against viral infections; however, they have more recently been shown to play protective or detrimental roles in many disease states. Type I IFNs consist of IFNα, IFNβ, IFNϵ, IFNκ, IFNω, and a few others, and they all signal through a shared receptor to exert a wide range of biological activities, including antiviral, antiproliferative, proapoptotic, and immunomodulatory effects. Though the individual type I IFN subtypes possess overlapping functions, there is growing appreciation that they also have unique properties. In this review, we summarize some of the mechanisms underlying differential expression of and signaling by type I IFNs, and we discuss examples of differential functions of IFNα and IFNβ in models of infectious disease, cancer, and autoimmunity.

IgE in the Pathogenesis of SLE: From Pathogenic Role to Therapeutic Target

Systemic lupus erythematosus (SLE) is a multifactorial chronic autoimmune disease, marked by the presence of autoantibodies to nuclear antigens belonging to different isotype classes. For several years, IgE antibodies have been incriminated in the development of allergic diseases and parasitic infections and different anti-IgE therapies have been developed to encounter the pathogenic role of IgE in these pathologies. Recently, multiple studies showed the presence of elevated total IgE levels and demonstrated a pathogenic role of autoreactive IgE in SLE. This review aims to summarize the findings incriminating IgE and autoreactive IgE in the pathophysiology of SLE, to describe their functional outcomes on their targeted cells as well as to discuss different IgE-related therapeutic modalities that emerged and that may be beneficial for SLE patient care.

Type I IFN-dependent antibody response at the basis of sex dimorphism in the outcome of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic, induces severe pneumonia mainly in elderly males. Epidemiological data clearly indicate sex-based differences in disease outcomes, with men accounting for about 70 % of deaths, despite similar susceptibility to infection. It is well known that females are endowed with higher capacity to produce antibodies, which correlates with viral clearance and disease resolution in the context of SARS-Cov-2 infection. Many X-linked immune genes escape X inactivation showing biallelic expression in female immune cells, particularly in plasmacytoid dendritic cells (pDCs). PDCs are more active in females and endowed with high capability to induce IFN-α-mediated B cell activation and differentiation into antibody-producing plasma cells throughout epigenetic mechanisms linked to trained immunity. Thus, we hypothesize that following SARS-CoV-2 infection, epigenetic modifications of X-linked genes involved in pDC-mediated type I IFN (IFN-I) signaling occurs more effectively in females, for inducing neutralizing antibody response as an immune correlate driving sex-biased disease outcome.

cDC1 are required for the initiation of collagen-induced arthritis

Rheumatoid arthritis (RA) is chronic autoimmune disease which etiology remains unknown. Several cell types have been described to potentiate/aggravate the arthritic process however the initiating event in synovial inflammation is still elusive. Dendritic cells (DCs) are essential for the initiation of primary immune responses and thus we hypothesized that these cells might be crucial for RA induction. DCs are a heterogeneous population of cells comprising different subsets with distinct phenotype and function. Here we investigated which DC subset(s) is/are crucial for the initiation of the arthritic process.

We have previously demonstrated that Flt3−/− mice, with reduced DCs, were protected from collagen induced arthritis (CIA). Here we have shown that GM-CSF derived DCs in Flt3L−/− mice are functional but not sufficient to induce arthritis. Batf3^−/− mice lacking both CD103⁺ and CD8α⁺ cDC1 were resistant to collagen induced arthritis (CIA), demonstrating that this DC subset is crucial for arthritis development. CEP-701 (a Flt3L inhibitor) treatment prevented CIA induction, and reduced dramatically the numbers CD103⁺ cDC1s present in the lymph nodes and synovium. Hence this study identified cDC1 as the main subset orchestrating the initiation of cell-mediated immunity in arthritis.

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Flt3L independent DCs present in Flt3L−/− mice are functional but are not sufficient to induce arthritis.

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BATF3−/− mice lacking cDC1 are protected from arthritis development indicating that cDC1 are necessary for disease induction.

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Treatment with a Flt3L inhibitor, CEP701, reduced cDC1 populations and prevented arthritis induction.

Psoriasis and Antimicrobial Peptides

Psoriasis is a systemic inflammatory disease caused by crosstalk between various cells such as T cells, neutrophils, dendritic cells, and keratinocytes. Antimicrobial peptides (AMPs) such as β-defensin, S100, and cathelicidin are secreted from these cells and activate the innate immune system through various mechanisms to induce inflammation, thus participating in the pathogenesis of psoriasis. In particular, these antimicrobial peptides enhance the binding of damage-associated molecular patterns such as self-DNA and self-RNA to their receptors and promote the secretion of interferon from activated plasmacytoid dendritic cells and keratinocytes to promote inflammation in psoriasis. Neutrophil extracellular traps (NETs), complexes of self-DNA and proteins including LL-37 released from neutrophils in psoriatic skin, induce Th17. Activated myeloid dendritic cells secrete a mass of inflammatory cytokines such as IL-12 and IL-23 in psoriasis, which is indispensable for the proliferation and survival of T cells that produce IL-17. AMPs enhance the production of some of Th17 and Th1 cytokines and modulate receptors and cellular signaling in psoriasis. Inflammation induced by DAMPs, including self-DNA and RNA released due to microinjuries or scratches, and the enhanced recognition of DAMPs by AMPs, may be involved in the mechanism underlying the Köbner phenomenon in psoriasis.

Hypersensitivity reactions to biologics (part II): classifications and current diagnostic and treatment approaches

Purpose

Biotechnological substances (BS) have rapidly expanded their clinical use. In parallel, there is an increase in expected or unexpected immunological or non-immunological adverse effects. In this part of the review, the current nomenclature of BSs, the classification of hypersensitivity reactions (HSR), as well as diagnostic and treatment approaches are documented to provide the tools to understand the nomenclature used throughout the databases and the need to harmonize it where applicable.

Methods

Detailed searches were performed on Pubmed, Web of Science, and Google Scholar to include all available publications. The search terms, such as specific BS, allergy, anaphylaxis, hypersensitivity, reactions, classification, diagnosis, grading, management, and desensitization, were determined for the search. Case reports, articles, and reviews on this subject were included.

Results

Today, a variety of non-standardized methods are used to support the clinical diagnosis. These include prick-to-prick tests and intradermal tests with the drug itself and its potentially allergenic ingredients. More rarely, anti-drug antibodies are detected and basophil activation tests are used by centers with research facilities. Although the treatment protocols for acute conditions vary, the overall approach is the same.

Conclusion

HSRs to BS are gradually increasing with the widening of their clinical use and indications. It is very important to prevent HSRs and to know the degree of severity as well as the emergency treatment algorithm. This review summarizes the diagnostic tests that should be applied: (a) immediately during/after a reaction, and (b) subsequently, and in the case that a switch of BS is not possible, desensitization is an option.

Antigen-specific immune decoys intercept and exhaust autoimmunity to prevent disease

Relapsing-remitting patterns of many autoimmune diseases such as multiple sclerosis (MS) are perpetuated by a recurring circuit of adaptive immune cells that amplify in secondary lymphoid organs (SLOs) and traffic to compartments where antigen is abundant to elicit damage. Some of the most effective immunotherapies impede the migration of immune cells through this circuit, however, broadly suppressing immune cell migration can introduce life-threatening risks for patients. We developed antigen-specific immune decoys (ASIDs) to mimic tissues targeted in autoimmunity and selectively intercept autoimmune cells to preserve host tissue. Using Experimental Autoimmune Encephalomyelitis (EAE) as a model, we conjugated autoantigen PLP_139-151 to a microporous collagen scaffold. By subcutaneously implanting ASIDs after induction but prior to the onset of symptoms, mice were protected from paralysis. ASID implants were rich with autoimmune cells, however, reactivity to cognate antigen was substantially diminished and apoptosis was prevalent. ASID-implanted mice consistently exhibited engorged spleens when disease normally peaked. In addition, splenocyte antigen-presenting cells were highly activated in response to PLP rechallenge, but CD3⁺ and CD19 ⁺ effector subsets were significantly decreased, suggesting exhaustion. ASID-implanted mice never developed EAE relapse symptoms even though the ASID material had long since degraded, suggesting exhausted autoimmune cells did not recover functionality. Together, data suggested ASIDs were able to sequester and exhaust immune cells in an antigen-specific fashion, thus offering a compelling approach to inhibit the migration circuit underlying autoimmunity.

Stimulation of tolerogenic dendritic cells using dexamethasone and 1,25-dihydroxyvitamin D3 represses autologous T cell activation and chondrocyte inflammation

Human osteoarthritis (OA) has been reclassified as a systemic musculoskeletal disorder involving activation of the innate and adaptive immune systems. Elevated pro-inflammatory cytokines may serve a key function in the development of the disease. 1,25-Dihydroxyvitamin D3 and dexamethasone (vitD3/Dex) may inhibit inflammation by acting on tolerogenic dendritic cells (tolDCs) in chronic inflammatory conditions. In the present study, DCs were isolated from peripheral blood mononuclear cells of patients with OA. DCs expressing high levels of co-stimulatory molecules maintain a tolerogenic phenotype under stimulation with LPS, which promotes DC maturation to generate tolDCs. When vitD3/Dex were added in the current study, the tolDCs produced pro-inflammatory cytokines, including low levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-10, and high levels of transforming growth factor-β. However, when vitD3/Dex were added to DCs without LPS stimulation, the levels of IL-10 were high. DCs with LPS stimulation increased the percentage of T-cells that produced IFN-γ and IL-17 and DCs with vitD3/Dex treatment alone increased the percentage of T-cells that produced IL-10 and FoxP3. However, those cytokines decrease in DCs co-processed with LPS and vitD3/Dex. The IL-10 release by the stimulated T cells was indicated to repress autologous T cell proliferation via soluble IL-10 and cell-cell contact. Furthermore, tolDCs and regulatory T cells suppressed matrix metalloproteinase (MMP)-1 and MMP-13 secretion by chondrocytes. Additionally, Akt and p38 mitogen-activated protein kinase signaling were demonstrated to be involved in the regulatory effects of Dec and vitD3 in DCs. The present findings suggest a novel mechanism underlying the beneficial effects of tolDCs, particularly in association with the pathogenesis of OA.

Imbalance of the two main circulating dendritic cell subsets in patients with myasthenia gravis

Although it is well documented that circulating dendritic cells (DCs) have specialized features during many kinds of physiological and pathological conditions, there are few reports about the features of DCs in the peripheral blood of myasthenia gravis (MG) patients. We investigated the quantitative and component features of DCs and their implications in MG. Peripheral blood samples from different kinds of MG patients were collected and their clinical characteristics were recorded. Using flow cytometry, we distinguished circulating DC subsets [plasmacytoid DCs (pDCs) and myeloid DCs (mDCs)] and enumerated their densities in peripheral blood. Absolute numbers of circulating pDCs were significantly decreased in naïve MG patients compared with healthy controls, resulting in a markedly lower ratio of the pDC to mDC percentage in total circulating DCs (pDCs/mDCs), suggesting an imbalance in the proportions of the two main circulating DC subsets. The clinical status of MG patients was improved after drug treatment, together with increased pDCs/mDCs. In a longitudinal follow-up, we observed that circulating mDCs were significantly reduced after 1 month of therapy with a corticosteroid and immunosuppressant, resulting in recovery of pDCs/mDCs. Although the exact meaning of the proportion change in circulating DC subsets is unknown, pDCs/mDCs might reflect the balance between the autoimmune response and immune tolerance of a patient. Moreover, changes in pDCs/mDCs during treatment might be a promising marker to predict the efficacy of a specific drug used for MG patients.

Lewis-antigen-containing ICAM-2/3 on Jurkat leukemia cells interact with DC-SIGN to regulate DC functions

Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is an important C-type lectin and plays a critical role in the recognition of pathogens and self-antigens. It has recently been shown that DC-SIGN directly interacts with acute T lymphoblastic leukemia cells. However, the mechanism regulating DC-SIGN-dependent DC association as well as related functions is still elusive. Here we showed that DC-SIGN preferentially bound to a set of malignant T lymphocytes, including Jurkat, CCRF-HSB2 and CCRF-CEM. ICAM-2/3 on Jurkat cells appeared to be the responsible ligands and the block of ICAM-2/3 dramatically impaired DC-SIGN association. We also found that ICAM-2/3 bear a considerable amount of Lewis X, Lewis Y and Lewis A residues, which are important for DC-SIGN recognition. Furthermore, transcriptome analysis revealed an upregulation of fucosyltransferase 4 (FUT4) in Jurkat cells and downregulating FUT4 limited DC-SIGN binding, indicating a previously unappreciated role of FUT4 in the control of Lewis antigens on malignant T lymphocytes. In addition, the presence of Jurkat cells impaired DC maturation and the block of DC-SIGN improved Jurkat cell-mediated effects on DC function and T cell differentiation. Together, we provide evidence that DC-SIGN orients DC association with acute T lymphoblastic leukemia cells and orchestrates DC functions.

Induction of Systemic Autoimmunity by a Xenobiotic Requires Endosomal TLR Trafficking and Signaling from the Late Endosome and Endolysosome but Not Type I IFN

Type I IFN and nucleic acid-sensing TLRs are both strongly implicated in the pathogenesis of lupus, with most patients expressing IFN-induced genes in peripheral blood cells and with TLRs promoting type I IFNs and autoreactive B cells. About a third of systemic lupus erythematosus patients, however, lack the IFN signature, suggesting the possibility of type I IFN-independent mechanisms. In this study, we examined the role of type I IFN and TLR trafficking and signaling in xenobiotic systemic mercury-induced autoimmunity (HgIA). Strikingly, autoantibody production in HgIA was not dependent on the type I IFN receptor even in NZB mice that require type I IFN signaling for spontaneous disease, but was dependent on the endosomal TLR transporter UNC93B1 and the endosomal proton transporter, solute carrier family 15, member 4. HgIA also required the adaptor protein-3 complex, which transports TLRs from the early endosome to the late endolysosomal compartments. Examination of TLR signaling pathways implicated the canonical NF-κB pathway and the proinflammatory cytokine IL-6 in autoantibody production, but not IFN regulatory factor 7. These findings identify HgIA as a novel type I IFN-independent model of systemic autoimmunity and implicate TLR-mediated NF-κB proinflammatory signaling from the late endocytic pathway compartments in autoantibody generation.

Hypermethylation of Interferon Regulatory Factor 8 (IRF8) Confers Risk to Vogt-Koyanagi-Harada Disease

Aberrant methylation change of IRF8 confers risk to various tumors, and abnormal expression of IRF8 is involved in many autoimmune diseases, including ocular Behcet’s disease. However, whether the methylation change of IRF8 is associated with Vogt-Koyanagi-Harada (VKH) disease remains unknown. In the present study, we found a decreased IRF8 mRNA expression in association with a higher methylation level in monocyte-derived dendritic cells (DCs) from active VKH patients compared with the normal and inactive subjects. DCs incubated with cyclosporin a (CsA) or dexamethasone (DEX) showed a lower methylation and higher mRNA expression of IRF8 in active VKH patients. A demethylation reagent, 5-Aza-2′-deoxycytidine (DAC) showed a notable demethylation effect as evidenced by increasing the mRNA expression and reducing the methylation level of IRF8. It also suppressed the Th1 and Th17 responses through down-regulating the expression of co-stimulatory molecules (CD86, CD80, CD40), and reducing the production of pro-inflammatory cytokines (IL-6, IL-1β, IL-23, IL-12) produced by DCs. These findings shows that hypermethylation of IRF8 in DCs confers risk to VKH disease. Demethylation of IRF8 may offer a novel therapeutic strategy protect against VKH disease.

Ocular Behcet's disease is associated with aberrant methylation of interferon regulatory factor 8 (IRF8) in monocyte-derived dendritic cells

Aberrant methylation of interferon regulatory factor 8 (IRF8) has been noted in various tumors. IRF8 has also been reported to be involved in many autoimmune diseases, including Behcet's disease (BD). However, the methylation status of IRF8 in BD has not been reported. To address this issue, we investigated whether the degree of methylation of IRF8 in dendritic cells (DCs) plays a role in the development of BD. We found a lower mRNA expression and a higher methylation level of IRF8 in active ocular BD patients as compared to normal subjects and inactive patients. Treatment with a demethylation agent, 5-Aza-2'-deoxycytidine (DAC) resulted in an increase of mRNA expression and a reduction of the IRF8 methylation level. It also down-regulated the expression of the co-stimulatory molecules CD86, CD80, CD40, and reduced the production of IL-6, IL-1β, IL-23 and IL-12. An inhibition of Th1/Th17 responses was observed as evidenced by a decreased production of IFN-γ, IL-17, and a reduction of IFN-γ/IL-17- producing CD4⁺ T cells following treatment with DAC. This study shows that active ocular BD patients have an aberrant IRF8 methylation status. These findings suggest that epigenetic control of IRF8 expression may offer a future target in the treatment of ocular BD.

The important roles of type I interferon and interferon-inducible genes in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a severe autoimmune disease that causes multiple-organ dysfunction mainly affecting women in their childbearing years. Type I IFN synthesis is usually triggered by viruses, and its production is tightly regulated and limited in time in health individuals. However, many patients with systemic autoimmune diseases including SLE have signs of aberrant production of type I interferon (IFN) and display an increased expression of IFN-inducible genes. Continuous type I IFNs derived from activated plasmacytoid dendritic cells (pDCs) by interferogenic immune complexes (ICs) and migration of these cells to tissues both break immune tolerance and promote an on-going autoimmune reaction in human body. By the means of detecting type I IFNs and IFN-inducible genes, it can help with diagnosis and evaluation of SLE in early stage and more efficiently. Anti-IFN-α monoclonal antibodies in SLE patients were recently reported and is now being investigated in phase II clinical trails. In this review, we focus on recent research progress in type I IFN and IFN-inducible genes. Possible mechanisms behind the dysregulated type I IFN system in SLE and how they contribute to the development of an autoimmune process, and act as a biomarker and therapeutic target will be reviewed.

Recognition of Endogenous Nucleic Acids by the Innate Immune System

Recognition of DNA and RNA by endosomal and cytosolic sensors constitutes a central element in the detection of microbial invaders by the innate immune system. However, the capacity of these sensors to discriminate between microbial and endogenous nucleic acids is limited. Over the past few years, evidence has accumulated to suggest that endogenous DNA or RNA species can engage nucleic-acid-sensing pattern-recognition receptors that can trigger or sustain detrimental pathology. Here, we review principles of how the activation of innate sensors by host nucleic acids is prevented in the steady state and discuss four important determinants of whether a nucleic-acid-driven innate response is mounted. These include structural features of the ligand being sensed, the subcellular location and quantity of pathogen-derived or endogenous nucleic acids, and the regulation of sensor-activation thresholds. Furthermore, we emphasize disease mechanisms initiated by failure to discriminate self from non-self in nucleic acid detection.

An efficient method for gene silencing in human primary plasmacytoid dendritic cells: silencing of the TLR7/IRF-7 pathway as a proof of concept

Plasmacytoid dendritic cells (pDC) are specialized immune cells that produce massive levels of type I interferon in response to pathogens. Unfortunately, pDC are fragile and extremely rare, rendering their functional study a tough challenge. However, because of their central role in numerous pathologies, there is a considerable need for an efficient and reproducible protocol for gene silencing in these cells. In this report, we tested six different methods for siRNA delivery into primary human pDC including viral-based, lipid-based, electroporation, and poly-ethylenimine (PEI) technologies. We show that lipid-based reagent DOTAP was extremely efficient for siRNA delivery into pDC, and did not induce cell death or pDC activation. We successfully silenced Toll-Like Receptor 7 (TLR7), CXCR4 and IFN regulatory factor 7 (IRF-7) gene expression in pDC as assessed by RT-qPCR or cytometry. Finally, we showed that TLR7 or IRF-7 silencing in pDC specifically suppressed IFN-α production upon stimulation, providing a functional validation of our transfection protocol.

Type I IFNs Regulate Inflammation, Vasculopathy, and Fibrosis in Chronic Cutaneous Graft-versus-Host Disease

Type I IFNs play a critical role in the immune response to viral infection and may also drive autoimmunity through modulation of monocyte maturation and promotion of autoreactive lymphocyte survival. Recent demonstrations of type I IFN gene signatures in autoimmune diseases, including scleroderma, led us to investigate the pathological role of IFNs in a preclinical model of sclerodermatous graft-versus-host disease. Using a neutralizing Ab against the type I IFN receptor IFNAR1, we observed a marked reduction in dermal inflammation, vasculopathy, and fibrosis compared with that seen in the presence of intact IFNAR1 signaling. The ameliorative effects of IFNAR1 blockade were restricted to the skin and were highly associated with inhibition of chronic vascular injury responses and not due to the inhibition of the T or B cell alloresponse. Inhibition of IFNAR1 normalized the overexpression of IFN-inducible genes in graft-versus-host disease skin and markedly reduced dermal IFN-α levels. Depletion of plasmacytoid dendritic cells, a major cellular source of type I IFNs, did not reduce the severity of fibrosis or type I IFN gene signature in the skin. Taken together, these studies demonstrate an important role for type I IFN in skin fibrosis, and they provide a rationale for IFNAR1 inhibition in scleroderma.

NUDT2 Disruption Elevates Diadenosine Tetraphosphate (Ap4A) and Down-Regulates Immune Response and Cancer Promotion Genes

Regulation of gene expression is one of several roles proposed for the stress-induced nucleotide diadenosine tetraphosphate (Ap₄A). We have examined this directly by a comparative RNA-Seq analysis of KBM-7 chronic myelogenous leukemia cells and KBM-7 cells in which the NUDT2 Ap₄A hydrolase gene had been disrupted (NuKO cells), causing a 175-fold increase in intracellular Ap₄A. 6,288 differentially expressed genes were identified with P < 0.05. Of these, 980 were up-regulated and 705 down-regulated in NuKO cells with a fold-change ≥ 2. Ingenuity^® Pathway Analysis (IPA^®) was used to assign these genes to known canonical pathways and functional networks. Pathways associated with interferon responses, pattern recognition receptors and inflammation scored highly in the down-regulated set of genes while functions associated with MHC class II antigens were prominent among the up-regulated genes, which otherwise showed little organization into major functional gene sets. Tryptophan catabolism was also strongly down-regulated as were numerous genes known to be involved in tumor promotion in other systems, with roles in the epithelial-mesenchymal transition, proliferation, invasion and metastasis. Conversely, some pro-apoptotic genes were up-regulated. Major upstream factors predicted by IPA^® for gene down-regulation included NFκB, STAT1/2, IRF3/4 and SP1 but no major factors controlling gene up-regulation were identified. Potential mechanisms for gene regulation mediated by Ap₄A and/or NUDT2 disruption include binding of Ap₄A to the HINT1 co-repressor, autocrine activation of purinoceptors by Ap₄A, chromatin remodeling, effects of NUDT2 loss on transcript stability, and inhibition of ATP-dependent regulatory factors such as protein kinases by Ap₄A. Existing evidence favors the last of these as the most probable mechanism. Regardless, our results suggest that the NUDT2 protein could be a novel cancer chemotherapeutic target, with its inhibition potentially exerting strong anti-tumor effects via multiple pathways involving metastasis, invasion, immunosuppression and apoptosis.

Decreased B and T lymphocyte attenuator in Behcet's disease may trigger abnormal Th17 and Th1 immune responses

Behcet's disease (BD) is a chronic, systemic and recurrent inflammatory disease associated with hyperactive Th17 and Th1 immune responses. Recent studies have shown that B and T lymphocyte attenuator (BTLA) negatively regulates the immune response. In this study, we investigated whether BTLA activation could be exploited to inhibit the development of abnormal immune responses in BD patients. BTLA expression in PBMCs and CD4(+) T cells was significantly decreased in active BD patients. Decreased BTLA level was associated with increased Th17 and Th1 responses. Activation of BTLA inhibited the abnormal Th17 and Th1 responses and IL-22 expression in both patients and controls. Addition of an agonistic anti-BTLA antibody remarkably inhibited DC-induced Th17 and Th1 cell responses, resulted in decreased production of the Th17 and Th1-related cytokines IL-1beta, IL-6, IL-23 and IL-12p70 and reduced CD40 expression in DCs. In conclusion, decreased BTLA expression in ocular BD may lead to inappropriate control of the Th17 and Th1 immune responses and DC functions. Therefore, BTLA may be involved in the development and recurrence of this disease. Agonistic agents of BTLA may represent a potential therapeutic approach for the treatment of BD and other inflammatory diseases mediated by abnormal Th17 and Th1 immune responses.

Local synthesis of interferon-alpha in lupus nephritis is associated with type I interferons signature and LMP7 induction in renal tubular epithelial cells

INTRODUCTION

Type I interferons are pivotal in the activation of autoimmune response in systemic lupus erythematous. However, the pathogenic role of interferon-alpha in patients affected by lupus nephritis remains uncertain. The aim of our study was to investigate the presence of a specific interferon signature in lupus nephritis and the effects of interferon-alpha at renal level.

METHODS

We performed immunohistochemical analysis for MXA-protein and in situ hybridization to detect interferon-alpha signature and production in human lupus nephritis. Through microarray studies, we analyzed the gene expression profile of renal tubular epithelial cells, stimulated with interferon-alpha. We validated microarray results through real-time polymerase chain reaction, flow cytometry on renal tubular epithelial cells, and through immunohistochemical analysis and confocal microscopy on renal biopsies.

RESULTS

Type I interferons signature was characterized by MXA-specific staining in renal tubular epithelial cells; in addition, in situ hybridization showed that renal tubular epithelial cells were the major producers of interferon-alpha, indicating a potential autocrine effect. Whole-genome expression profile showed interferon-alpha induced up-regulation of genes involved in innate immunity, protein ubiquitination and switching to immunoproteasome. In accordance with the in vitro data, class IV lupus nephritis showed up-regulation of the immunoproteasome subunit LMP7 in tubular epithelial cells associated with type I interferon signature.

CONCLUSIONS

Our data indicate that type I interferons might have a pathogenic role in lupus nephritis characterized by an autocrine effect of interferon-alpha on renal tubular epithelial cells. Therefore we hypothesize that inhibition of type I interferons might represent a therapeutic target to prevent tubulo-interstitial damage in patients with lupus nephritis.

Alternatively activated dendritic cells derived from systemic lupus erythematosus patients have tolerogenic phenotype and function

Tolerogenic dendritic cells (DCs) are potential cell-based therapy in autoimmune diseases. In this study, we generated alternatively activated DCs (aaDCs) by treating monocyte-derived DCs from patients with systemic lupus erythematosus (SLE) and healthy subjects with combination of 1,25 dihydroxyvitamin D(3) (vitD3) and dexamethasone followed by lipopolysaccharide-induced maturation. Lupus aaDCs were found to acquire semi-mature phenotype that remained maturation-resistant to immunostimulants. They produced low level of IL-12 but high level of IL-10. They had attenuated allostimulatory effects on T cell activation and proliferation comparable to normal aaDCs and demonstrated differential immunomodulatory effects on naïve and memory T cells. These aaDCs were capable of inducing IL-10 producing regulatory T effectors from naïve T cells whereas they modulated cytokine profile with suppressed production of IFN-γ and IL-17 by co-cultured memory T cells with attenuated proliferation. These aaDCs were shown to be superior to those generated using vitD3 alone in lupus patients.

Activation of the aryl hydrocarbon receptor affects activation and function of human monocyte-derived dendritic cells

Aryl hydrocarbon receptor (AhR) is well known for mediating the toxic effects of dioxin-containing pollutants, but has also been shown to be involved in the natural regulation of the immune response. In this study, we investigated the effect of AhR activation by its endogenous ligands 6-formylindolo[3,2-b]carbazole (FICZ) and 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) on the differentiation, maturation and function of monocyte-derived DCs in Behçet's disease (BD) patients. In this study, we showed that AhR activation by FICZ and ITE down-regulated the expression of co-stimulatory molecules including human leucocyte antigen D-related (HLA-DR), CD80 and CD86, while it had no effect on the expression of CD83 and CD40 on DCs derived from BD patients and normal controls. Lipopolysaccharide (LPS)-treated dendritic cells (DCs) from active BD patients showed a higher level of interleukin (IL)-1β, IL-6, IL-23 and tumour necrosis factor (TNF)-α production. FICZ or ITE significantly inhibited the production of IL-1β, IL-6, IL-23 and TNF-α, but induced IL-10 production by DCs derived from active BD patients and normal controls. FICZ or ITE-treated DCs significantly inhibited the T helper type 17 (Th17) and Th1 cell response. Activation of AhR either by FICZ or ITE inhibits DC differentiation, maturation and function. Further studies are needed to investigate whether manipulation of the AhR pathway may be used to treat BD or other autoimmune diseases.

New insights into the pathogenesis and management of lupus in children

Systemic lupus erythematosus (SLE) is the archetypal systemic autoimmune disease, characterised by inflammation causing a wide spectrum of major clinical manifestations that may affect any organ. Childhood-onset SLE (cSLE) is more severe with greater damage and drug burden than adult-onset SLE. Understanding the pathogenesis of cSLE is a key step in directing medical management. The dysregulated immune system, that in health is usually vital in protecting the body from infection, contributes significantly to the disease process. Improved knowledge of disease mechanism will help to identify potential targets for novel agents and the identification of new biomarkers of disease activity. This review will present current knowledge of the innate and adaptive immune responses in cSLE and the optimal patient management that aims to control the disease. Innate immune dysregulation includes the overexpression of interferon-α, dendritic cell activation, neutrophil extracellular traps and phagocyte abnormalities. The classical adaptive immune system is over activated in lupus with excessive autoantibody production due to abnormalities in B and T cell regulation. Novel biologic medications are being developed to specifically target these areas with the ultimate aim of improving the long-term outlook and quality of life for children living with Lupus.

IFN priming is necessary but not sufficient to turn on a migratory dendritic cell program in lupus monocytes

Blood monocytes from children with systemic lupus erythematosus (SLE) behave similar to dendritic cells (DCs), and SLE serum induces healthy monocytes to differentiate into DCs in a type I IFN-dependent manner. In this study, we found that these monocytes display significant transcriptional changes, including a prominent IFN signature, compared with healthy controls. Few of those changes, however, explain DC function. Exposure to allogeneic T cells in vitro reprograms SLE monocytes to acquire DC phenotype and function, and this correlates with both IFN-inducible (IP10) and proinflammatory cytokine (IL-1β and IL6) expression. Furthermore, we found that both IFN and SLE serum induce the upregulation of CCR7 transcription in these cells. CCR7 protein expression, however, requires a second signal provided by TLR agonists such as LPS. Thus, SLE serum "primes" a subset of monocytes to readily (<24 h) respond to TLR agonists and acquire migratory DC properties. Our findings might explain how microbial infections exacerbate lupus.

Interferon-α is not elevated in idiopathic thrombotic thrombocytopenic purpura patients

Idiopathic thrombotic thrombocytopenic purpura (TTP) patients have ADAMTS13 deficiency, which is usually caused by ADAMTS13 autoantibodies. However, the triggering factors for the autoantibody production remain unclear. Interferon-α (IFN-α) is a cytokine involved with many autoimmune processes such as inducing the activation of peripheral dendritic cells and stimulating T cells and B cells. It also plays an important role in some autoimmune diseases. Elevated IFN-α levels have been observed in some TTP patients and previous case reports have shown the occurrence of TTP after IFN-α treatment. Thus, we hypothesized that high levels of IFN-α would correlate with presence of ADAMTS13 autoantibodies. However, we did not observe elevated IFN-α levels in 36 TTP patients (mean 5.29 pg/ml, standard deviation (SD) 26.56 pg/ml) compared to healthy controls (mean 0 pg/ml, SD 0 pg/ml), P = 0.59. IFN-α levels of most patients (94%) were undetectable. Only two patients had increased IFN-α levels and ADAMTS13 autoantibodies were detected in these two patients. Interestingly, both the patients had an underlying autoimmune disease. Although there have been cases of secondary TTP following IFN-α treatment, no evidence supports a role of IFN-α in the development of idiopathic TTP in our patient population.

Regulation of type I interferon responses

Type I interferons (IFNs) activate intracellular antimicrobial programmes and influence the development of innate and adaptive immune responses. Canonical type I IFN signalling activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, leading to transcription of IFN-stimulated genes (ISGs). Host, pathogen and environmental factors regulate the responses of cells to this signalling pathway and thus calibrate host defences while limiting tissue damage and preventing autoimmunity. Here, we summarize the signalling and epigenetic mechanisms that regulate type I IFN-induced STAT activation and ISG transcription and translation. These regulatory mechanisms determine the biological outcomes of type I IFN responses and whether pathogens are cleared effectively or chronic infection or autoimmune disease ensues.

SeXX matters in immunity

The significant contributions of sex to an immune response, specifically in the context of the sex bias observed in susceptibility to infectious and autoimmune diseases and their pathogenesis, have until recently, largely been ignored and understudied. This review highlights recent findings related to sex-specific factors that provide new insights into how sex determines the transcriptome, the microbiome, and the consequent immune cell functional profile to define an immune response. Unquestionably, accumulating data confirm that sex matters and must be a consideration when decisions around therapeutic intervention strategies are developed.

Human plasmacytoid dendritic cells: from molecules to intercellular communication network

Plasmacytoid dendritic cells (pDCs) are a specific subset of naturally occurring dendritic cells, that secrete large amounts of Type I interferon and play an important role in the immune response against viral infection. Several studies have highlighted that they are also effective antigen presenting cells, making them an interesting target for immunotherapy against cancer. However, the modes of action of pDCs are not restricted to antigen presentation and IFN secretion alone. In this review we will highlight a selection of cell surface proteins expressed by human pDCs that may facilitate communication with other immune cells, and we will discuss the implications of these molecules for pDC-driven immune responses.

The tiers and dimensions of evasion of the type I interferon response by human cytomegalovirus

Human cytomegalovirus (HCMV) is a member of the β-herpesvirus family that invariably occupies hosts for life despite a consistent multi-pronged antiviral immune response that targets the infection. This persistence is enabled by the large viral genome that encodes factors conferring a wide assortment of sophisticated, often redundant phenotypes that disable or otherwise manipulate impactful immune effector processes. The type I interferon system represents a first line of host defense against infecting viruses. The physiological reactions induced by secreted interferon act to effectively block replication of a broad spectrum of virus types, including HCMV. As such, the virus must exhibit counteractive mechanisms to these responses that involve their inhibition, tolerance, or re-purposing. The goal of this review is to describe the impact of the type I interferon system on HCMV replication and to showcase the number and diversity of strategies employed by the virus that allow infection of hosts in the presence of interferon-dependent activity.

Cutaneous sarcoidosis in a chronic hepatitis C patient receiving pegylated interferon and ribavirin therapy

A 61-year-old Japanese woman suffered from a small, painful, subcutaneous nodule on the sole of her foot that was 10 mm across in diameter during pegylated interferon (PEG IFN) and ribavirin (RBV) combination therapy for chronic hepatitis C. Skin biopsy revealed multiple non-caseating granulomas composed of epithelioid histiocytes with multinucleate giant cells, which was consistent with sarcoidosis. Ophthalmologic examination revealed uveitis. Thoracic computed tomography (CT) showed multiple bilateral hilar lymphadenopathies and a diffuse micronodular interstitial pattern of the lungs. Genetic analysis indicated a probable homozygous haplotype of A*02:01-C*15:02-B*51:01-DRB1*16:02-DQB1*05:02 in human leukocyte antigen regions. The patient was observed carefully without any additional medication because no significant systemic symptoms were noted. Combination therapy was continued for 2 months afterwards. She was asymptomatic for over 3 years of follow up, and repeated hematological and biological investigations and chest CT showed improvement. In conclusion, clinicians should bear sarcoidosis in mind as a complication during PEG IFN and RBV combination therapy. They should also be aware of the usually good prognosis of PEG IFN-induced cutaneous sarcoidosis in order not to prematurely discontinue a treatment necessary for liver disease; maintenance of PEG IFN treatment may be advised with careful follow up.

CD20 antibody primes B lymphocytes for type I interferon production

CD20 is a B cell surface marker that is expressed in various stages in B lymphocytes and certain lymphomas. Clinical administration of CD20 antibody, such as rituximab, is used widely to treat human B-cell lymphomas and other diseases. However, CD20 antibody failed to treat systemic lupus erythematosus (SLE or lupus). The reason for the failure is currently unknown. Type I interferons (IFN) are a major component for the host innate immunity, and a key pathogenic factor in lupus. We found that CD20 antibody potentiated human B cells for its production of IFNs in vitro. This function was specific to CD20-expressing cells and the potentiation function seems to be instant. In addition, ectopic expression of CD20 in non-B-lymphocytes increased the IFN promoter reporter activities. Because IFNs are a key pathogenic factor in lupus, our data suggest that, in the presence of virus infection, the CD20-antibody-mediated enhancement of IFN production might be related to its failure in lupus treatments. This work may provide new insights for CD20-Ab therapeutic applications.

Molecular control of steady-state dendritic cell maturation and immune homeostasis

Dendritic cells (DCs) are specialized sentinels responsible for coordinating adaptive immunity. This function is dependent upon coupled sensitivity to environmental signs of inflammation and infection to cellular maturation-the programmed alteration of DC phenotype and function to enhance immune cell activation. Although DCs are thus well equipped to respond to pathogens, maturation triggers are not unique to infection. Given that immune cells are exquisitely sensitive to the biological functions of DCs, we now appreciate that multiple layers of suppression are required to restrict the environmental sensitivity, cellular maturation, and even life span of DCs to prevent aberrant immune activation during the steady state. At the same time, steady-state DCs are not quiescent but rather perform key functions that support homeostasis of numerous cell types. Here we review these functions and molecular mechanisms of suppression that control steady-state DC maturation. Corruption of these steady-state operatives has diverse immunological consequences and pinpoints DCs as potent drivers of autoimmune and inflammatory disease.

Expression of ESE-3 isoforms in immunogenic and tolerogenic human monocyte-derived dendritic cells

Dendritic cells (DC) are the only hematopoietic cells expressing the epithelial specific Ets transcription factor ESE-3. Here we analyzed presence and quantity of isoforms ESE-3a, ESE-3b and ESE-3j in various immunogenic and tolerogenic human monocyte-derived DC (moDC) and blood DC populations using quantitative real time PCR and immunoblot analyses. ESE-3a and ESE-3b were detectable in all moDC populations with ESE-3b being the main transcript. ESE-3b expression was upregulated in immunogenic moDC and downregulated in tolerogenic moDC compared to immature moDC. ESE-3a had similar transcript levels in immature and immunogenic moDC and had very low levels in tolerogenic moDC. In blood DC populations only splice variant ESE-3b was detectable. ESE-3j was not detectable in any of the DC populations. These findings suggest that ESE-3b is the functionally most important ESE-3 isoform in DC.

Toll-like receptor-2 agonist-allergen coupling efficiently redirects Th2 cell responses and inhibits allergic airway eosinophilia

Toll-like receptor (TLR) agonists beneficially modulate allergic airway inflammation. However, the efficiency of TLR agonists varies considerably, and their exact cellular mechanisms (especially of TLR 2/6 agonists) are incompletely understood. We investigated at a cellular level whether the administration of the pharmacologically improved TLR2/6 agonist S-[2,3-bispalmitoyiloxy-(2R)-propyl]-R-cysteinyl-amido-monomethoxy polyethylene glycol (BPP) conjugated to antigenic peptide (BPP-OVA) could divert an existing Th2 response and influence airway eosinophilia. The effects of BPP-OVA on airway inflammation were assessed in a classic murine sensitization/challenge model and an adoptive transfer model, which involved the adoptive transfer of in vitro differentiated ovalbumin (OVA)-specific Th2 cells. Functional T-cell stimulation by lung dendritic cells (DCs) was determined both in vitro and in vivo, combined with a cytokine secretion analysis. A single mucosal application of BPP-OVA efficiently delivered antigen, led to TLR2-mediated DC activation, and resulted in OVA-specific T-cell proliferation via lung DCs in vivo. In alternative models of allergic airway disease, a single administration of BPP-OVA before OVA challenge (but not BPP alone) significantly reduced airway eosinophilia, most likely through altered antigen-specific T-cell stimulation via DCs. Analyses of adoptively transferred Th2-biased cells after BPP-OVA administration in vivo suggested that BPP-OVA guides antigen-specific Th2 cells to produce significantly higher amounts of IFN-γ upon allergen challenge. In conclusion, our data show for the first time that a single mucosal administration of a TLR 2/6 agonist-allergen conjugate can provoke IFN-γ responses in Th2-biased cells and alleviate allergic airway inflammation.

Toll-like receptor 7 stimulates the expression of Epstein-Barr virus latent membrane protein 1

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus. Toll-like receptor 7 (TLR7) is involved in host innate immunity against pathogens, and its aberrant activation is linked to the development of systemic lupus erythematosus (SLE, also called “lupus”). Type I interferons (IFN) are apparently driving forces for lupus pathogenesis. Previously, we found that EBV latent membrane protein 1 (LMP1) primes cells for IFN production. In this report, the relationship among EBV LMP1, TLRs, and IFN production are examined. We find that TLR7 activation increases the expression of EBV LMP1, and IFN regulatory factor 7 (IRF7) is involved in the stimulation process. TLR7 activation did not induce IFNs from EBV-infected cells, but potentiates those cells for IFN production by TLR3 or TLR9 activation. In addition, we find that LMP1 and IFNs are co-expressed in the same cells in some lupus patients. Therefore, the aberrant activation of TLR7 might induce LMP1 expression and LMP1-expression cells may be producing IFNs in lupus patients. These results suggest EBV might be an exacerbating factor in some lupus patients via promoting IFN production.