The impact of glycosylation on HLA-DR1-restricted T cell recognition of type II collagen in a mouse model

Oral Administration of Protease-Soluble Chicken Type II Collagen Ameliorates Anterior Cruciate Ligament Transection-Induced Osteoarthritis in Rats

This study investigated whether oral supplementation with protease-soluble chicken type II collagen (PSCC-II) mitigates the progression of anterior cruciate ligament transection (ACLT)-induced osteoarthritis (OA) in rats. Eight-week-old male Wistar rats were randomly assigned to the following groups: control, sham, ACLT, group A (ACLT + pepsin-soluble collagen type II collagen (C-II) with type I collagen), group B (ACLT + Amano M-soluble C-II with type I collagen), group C (ACLT + high-dose Amano M-soluble C-II with type I collagen), and group D (ACLT + unproteolyzed C-II). Various methods were employed to analyze the knee joint: nociceptive tests, microcomputed tomography, histopathology, and immunohistochemistry. Rats treated with any form of C-II had significant reductions in pain sensitivity and cartilage degradation. Groups that received PSCC-II treatment effectively mitigated the ACLT-induced effects of OA concerning cancellous bone volume, trabecular number, and trabecular separation compared with the ACLT alone group. Furthermore, PSCC-II and unproteolyzed C-II suppressed ACLT-induced effects, such as the downregulation of C-II and upregulation of matrix metalloproteinase-13, tumor necrosis factor-α, and interleukin-1β. These results indicate that PSCC-II treatment retains the protective effects of traditional undenatured C-II and provide superior benefits for OA management. These benefits encompass pain relief, anti-inflammatory effects, and the protection of cartilage and cancellous bone.

Dexamethasone and Monophosphoryl Lipid A-Modulated Dendritic Cells Promote Antigen-Specific Tolerogenic Properties on Naive and Memory CD4+ T Cells

Tolerogenic dendritic cells (DCs) are a promising tool to control T cell-mediated autoimmunity. Here, we evaluate the ability of dexamethasone-modulated and monophosphoryl lipid A (MPLA)-activated DCs [MPLA-tolerogenic DCs (tDCs)] to exert immunomodulatory effects on naive and memory CD4⁺ T cells in an antigen-specific manner. For this purpose, MPLA-tDCs were loaded with purified protein derivative (PPD) as antigen and co-cultured with autologous naive or memory CD4⁺ T cells. Lymphocytes were re-challenged with autologous PPD-pulsed mature DCs (mDCs), evaluating proliferation and cytokine production by flow cytometry. On primed-naive CD4⁺ T cells, the expression of regulatory T cell markers was evaluated and their suppressive ability was assessed in autologous co-cultures with CD4⁺ effector T cells and PPD-pulsed mDCs. We detected that memory CD4⁺ T cells primed by MPLA-tDCs presented reduced proliferation and proinflammatory cytokine expression in response to PPD and were refractory to subsequent stimulation. Naive CD4⁺ T cells were instructed by MPLA-tDCs to be hyporesponsive to antigen-specific restimulation and to suppress the induction of T helper cell type 1 and 17 responses. In conclusion, MPLA-tDCs are able to modulate antigen-specific responses of both naive and memory CD4⁺ T cells and might be a promising strategy to “turn off” self-reactive CD4⁺ effector T cells in autoimmunity.

Unraveling the Effect of Immunogenicity on the PK/PD, Efficacy, and Safety of Therapeutic Proteins

Biologics have emerged as a powerful and diverse class of molecular and cell-based therapies that are capable of replacing enzymes, editing genomes, targeting tumors, and more. As this complex array of tools arises a distinct set of challenges is rarely encountered in the development of small molecule therapies. Biotherapeutics tend to be big, bulky, polar molecules comprised of protein and/or nucleic acids. Compared to their small molecule counterparts, they are fragile, labile, and heterogeneous. Their biodistribution is often limited by hydrophobic barriers which often restrict their administration to either intravenous or subcutaneous entry routes. Additionally, their potential for immunogenicity has proven to be a challenge to developing safe and reliably efficacious drugs. Our discussion will emphasize immunogenicity in the context of therapeutic proteins, a well-known class of biologics. We set out to describe what is known and unknown about the mechanisms underlying the interplay between antigenicity and immune response and their effect on the safety, efficacy, pharmacokinetics, and pharmacodynamics of these therapeutic agents.

Antimicrobial peptides from scorpion venoms

The need for new antimicrobial agents is becoming one of the most urgent requirements in modern medicine. The venoms of many different species are rich sources of biologically active components and various therapeutic agents have been characterized including antimicrobial peptides (AMPs). Due to their potent activity, low resistance rates and unique mode of action, AMPs have recently received much attention. This review focuses on AMPs from the venoms of scorpions and examines all classes of AMPs found to date. It gives details of their biological activities with reference to peptide structure. The review examines the mechanism of action of AMPs and with this information, suggests possible mechanisms of action of less well characterised peptides. Finally, the review examines current and future trends of scorpion AMP research, by discussing recent successes obtained through proteomic and transcriptomic approaches.

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In-depth analysis of AMPs from scorpion venom.

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Focus on biological activity and structure – function relationships.

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Discussion of possible mechanisms of action.

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Future strategies for further mining of bioactive compounds from venoms.

Challenges and approaches for the development of safer immunomodulatory biologics

Immunomodulatory biologics are a class of biotechnology-derived therapeutic products that are designed to engage immune-relevant targets and are indicated in the treatment and management of a range of diseases, including immune-mediated inflammatory diseases and malignancies.

Despite their high specificity and therapeutic advantages, immmunomodulatory biologics have been associated with adverse reactions such as serious infections, malignancies and cytokine release syndrome, which arise owing to the on-target or exaggerated pharmacological effects of these drugs. Immunogenicity resulting in the generation of antidrug antibodies is another unwanted effect that leads to loss of efficacy and — rarely — hypersensitivity reactions.

For some adverse reactions, mitigating and preventive strategies are in place, such as stratifying patients on the basis of responsiveness to therapy and the risk of developing adverse reactions. These strategies depend on the availability of robust biomarkers for therapeutic efficacy and the risk of adverse reactions: for example, seropositivity for John Cunningham virus is a risk factor for progressive multifocal leukoencephalopathy. The development of effective biomarkers will greatly aid these strategies.

The development and design of safer immunomodulatory biologics is reliant on a detailed understanding of the nature of the disease, target biology, the interaction of the target with the immunomodulatory biologic and the inherent properties of the biologic that elicit unwanted effects.

The availability of in vitro and in vivo models that can be used to predict adverse reactions associated with immunomodulatory biologics is central to the development of safer immunomodulatory biologics. Some progress has been made in developing in vitro and in silico tests for predicting cytokine release syndrome and immunogenicity, but there is still a lack of models for effectively predicting infections and malignancies.

Two pathways can be followed in designing and developing safer immunomodulatory biologics. The first pathway involves generating a biologic that engages an alternative target or mechanism to produce the desired pharmacodynamic effect without the associated adverse reaction, and is followed when the adverse reaction cannot be dissociated from the target biology. The second pathway involves redesigning the biologic to 'engineer out' components within the biologic structure that trigger adverse effects or to alter the nature of the target–biologic interactions.

Owing to their specificity, immunomodulatory biologics generally have better safety profiles than small-molecule drugs. However, adverse effects such as an increased risk of infections or cytokine release syndrome are of concern. Here, Park and colleagues discuss the current strategies used to predict and mitigate these adverse effects and consider how they can be used to inform the development of safer immunomodulatory biologics.

Immunomodulatory biologics, which render their therapeutic effects by modulating or harnessing immune responses, have proven their therapeutic utility in several complex conditions including cancer and autoimmune diseases. However, unwanted adverse reactions — including serious infections, malignancy, cytokine release syndrome, anaphylaxis and hypersensitivity as well as immunogenicity — pose a challenge to the development of new (and safer) immunomodulatory biologics. In this article, we assess the safety issues associated with immunomodulatory biologics and discuss the current approaches for predicting and mitigating adverse reactions associated with their use. We also outline how these approaches can inform the development of safer immunomodulatory biologics.

Commercial proteases: present and future

This review presents a brief overview of the general categories of commercially used proteases, and critically surveys the successful strategies currently being used to improve the properties of proteases for various commercial purposes. We describe the broad application of proteases in laundry detergents, food processing, and the leather industry. The review also introduces the expanding development of proteases as a class of therapeutic agents, as well as highlighting recent progress in the field of protease engineering. The potential commercial applications of proteases are rapidly growing as recent technological advances are producing proteases with novel properties and substrate specificities.

Immunogenicity to biologics: mechanisms, prediction and reduction

Currently, there is a significant rise in the development and clinical use of a unique class of pharmaceuticals termed as Biopharmaceuticals or Biologics, in the management of a range of disease conditions with, remarkable therapeutic benefits. However, there is an equally growing concern regarding development of adverse effects like immunogenicity in the form of anti-drug antibodies (ADA) production and hypersensitivity. Immunogenicity to biologics represents a significant hurdle in the continuing therapy of patients in a number of disease settings. Efforts focussed on the identification of factors that contribute towards the onset of immunogenic response to biologics have led to reductions in the incidence of immunogenicity. An in-depth understanding of the cellular and molecular mechanism underpinning immunogenic responses will likely improve the safety profile of biologics. This review addresses the mechanistic basis of ADA generation to biologics, with emphasis on the role of antigen processing and presentation in this process. The article also addresses the potential contribution of complement system in augmenting or modulating this response. Identifying specific factors that influences processing and presentation of biologic-derived antigens in different genotype and disease background may offer additional options for intervention in the immunogenic process and consequently, the management of immunogenicity to biologics.

[Juvenile arthritides]

Arthritis in children represents a diagnostic and therapeutic challenge. The diagnostic spectrum is broad and a very precise indication for diagnostic and therapeutic procedures, especially in small children, is important. In addition to acute arthritides - viral arthritis, reactive arthritis, Lyme arthritis and septic arthritis - secondary chronic arthritis related to an underlying disease as well as juvenile idiopathic arthritis (JIA), the most common chronic inflammatory systemic disease in children, need to be considered. This overview is a guide to the diagnosis of arthritis in childhood and to evidence-based therapy of JIA in particular. This consists of a combination of nonsteroidal anti-inflammatory drugs, systemic and intraarticular corticosteroids, traditional DMARDs such as sulfasalazine, methotrexate and leflunomide, the TNF inhibitors etanercept, adalimumab and, with restrictions, infliximab, other biopharmaceuticals such as anakinra, canakinumab and rilonacept, and tocilizumab and finally, abatacept.

Mice producing less reactive oxygen species are relatively resistant to collagen glycopeptide vaccination against arthritis

The bottleneck for the induction of collagen-induced arthritis in mice is the recognition of immunodominant type II collagen (CII) peptide (CII259-273) bound to the MHC class II molecule A(q). We have shown previously that the posttranslationally glycosylated lysine at position 264 in this epitope is of great importance for T cell recognition and tolerance induction to CII as well as for arthritis development. The Ncf1 gene, controlling oxidative burst, has been shown to play an important role for immune tolerance to CII. To investigate the effect of oxidation on the efficiency of immune-specific vaccination with MHC class II/glycosylated-CII peptide complexes, we used Ncf1 mutated mice. We demonstrate that normal reactive oxygen species (ROS) levels contribute to the establishment of tolerance and arthritis protection, because only mice with a functional oxidative burst were completely protected from arthritis after administration of the glycosylated CII259-273 peptide in complex with MHC class II. Transfer of T cells from vaccinated mice with functional Ncf1 protein resulted in strong suppression of clinical signs of arthritis in B10.Q mice, whereas the Ncf1 mutated mice as recipients had a weaker suppressive effect, suggesting that ROS modified the secondary rather than the primary immune response. A milder but still significant effect was also observed in ROS deficient mice. During the primary vaccination response, regulatory T cells, upregulation of negative costimulatory molecules, and increased production of anti-inflammatory versus proinflammatory cytokines in both Ncf1 mutated and wild type B10.Q mice was observed, which could explain the vaccination effect independent of ROS.

The preclinical stages of RA: lessons from human studies and animal models

Rheumatoid arthritis (RA) is a systemic autoimmune disorder based in the synovium of peripheral joints. Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) are autoantibodies detectable in the majority of patients, with the latter being highly specific for RA. Retrospective studies utilizing preclinical serum samples have demonstrated that RF and ACPAs are detectable in the serum of RA patients months to years before disease onset. Moreover, a close association between ACPAs, smoking, and disease-predisposing HLA-DRB1 alleles has been identified, suggesting that these risk factors may converge to precipitate autoantibody-positive RA. Animal models of RA have added considerable information regarding the immune events that precede joint inflammation. These models have demonstrated that autoantibodies to ubiquitous antigens can directly precipitate chronic organ-specific inflammation centred in the joint. Furthermore, it has recently been possible to demonstrate a role for ACPAs in the animal models of RA. The major challenge currently is to develop a robust predictive model for RA onset, identifying the factors that serve to initiate, amplify, and mature the immune responses towards citrullinated autoantigens. Recent data from a high-risk population of RA family members indicate that the nature and specificity of the ACPA response in healthy individuals differs considerably from that in RA patients, and support the concept that this autoimmune response evolves over time and leads to the onset of clinically detectable synovitis. Ultimately, the availability of data from prospective studies of RA onset will allow for novel strategies that can potentially prevent disease in high-risk individuals.

Structure and pathogenicity of antibodies specific for citrullinated collagen type II in experimental arthritis

Antibodies to citrulline-modified proteins have a high diagnostic value in rheumatoid arthritis (RA). However, their biological role in disease development is still unclear. To obtain insight into this question, a panel of mouse monoclonal antibodies was generated against a major triple helical collagen type II (CII) epitope (position 359-369; ARGLTGRPGDA) with or without arginines modified by citrullination. These antibodies bind cartilage and synovial tissue, and mediate arthritis in mice. Detection of citrullinated CII from RA patients' synovial fluid demonstrates that cartilage-derived CII is indeed citrullinated in vivo. The structure determination of a Fab fragment of one of these antibodies in complex with a citrullinated peptide showed a surprising beta-turn conformation of the peptide and provided information on citrulline recognition. Based on these findings, we propose that autoimmunity to CII, leading to the production of antibodies specific for both native and citrullinated CII, is an important pathogenic factor in the development of RA.

LPS activation is required for migratory activity and antigen presentation by tolerogenic dendritic cells

Autoimmune pathologies are caused by a breakdown in self-tolerance. Tolerogenic dendritic cells (tolDC) are a promising immunotherapeutic tool for restoring self-tolerance in an antigen-specific manner. Studies about tolDC have focused largely on generating stable maturation-resistant DC, but few have fully addressed questions about the antigen-presenting and migratory capacities of these cells, prerequisites for successful immunotherapy. Here, we investigated whether human tolDC, generated with dexamethasone and the active form of vitamin D3, maintained their tolerogenic function upon activation with LPS (LPS-tolDC), while acquiring the ability to present exogenous autoantigen and to migrate in response to the CCR7 ligand CCL19. LPS activation led to important changes in the tolDC phenotype and function. LPS-tolDC, but not tolDC, expressed the chemokine receptor CCR7 and migrated in response to CCL19. Furthermore, LPS-tolDC were superior to tolDC in their ability to present type II collagen, a candidate autoantigen in rheumatoid arthritis. tolDC and LPS-tolDC had low stimulatory capacity for allogeneic, naïve T cells and skewed T cell polarization toward an anti-inflammatory phenotype, although LPS-tolDC induced significantly higher levels of IL-10 production by T cells. Our finding that LPS activation is essential for inducing migratory and antigen-presenting activity in tolDC is important for optimizing their therapeutic potential.

HLA-DM negatively regulates HLA-DR4-restricted collagen pathogenic peptide presentation and T cell recognition

Rheumatoid arthritis, an autoimmune disease, is significantly associated with the HLA class II allele HLA-DR4. While the etiology of rheumatoid arthritis remains unknown, type II collagen (CII) is a candidate autoantigen. An immunodominant pathogenic epitope from this autoantigen, CII(261-273), which binds to HLA-DR4 and activates CD4+ T cells, has been identified. The non-classical class II antigen, HLA-DM, is also a key component of class II antigen presentation pathways influencing peptide presentation by HLA-DR molecules expressed on professional antigen-presenting cells (APC). Here, we investigated whether the HLA-DR4-restricted presentation of the pathogenic CII(261-273) epitope was regulated by HLA-DM expression in APC. We show that APC lacking HLA-DM efficiently display the CII(261-273) peptide/epitope to activate CD4+ T cells, and that presentation of this peptide is modulated dependent on the level of HLA-DM expression in APC. Mechanistic studies demonstrated that the CII(261-273) peptide is internalized by APC and edited by HLA-DM molecules in the recycling pathway, inhibiting peptide presentation and T cell recognition. These findings suggest that HLA-DM expression in APC controls class II-mediated CII(261-273) peptide/epitope presentation and regulates CD4+ T cell responses to this self epitope, thus potentially influencing CII-dependent autoimmunity.

An extremely diverse CD4 response to vaccinia virus in humans is revealed by proteome-wide T-cell profiling

CD4 T cells are required for the maintenance and recall of antiviral CD8 T cells and for antibody responses. Little is known concerning the overall architecture of the CD4 response to complex microbial pathogens. In a whole-proteome approach, 180 predicted open reading frames (ORFs) in the vaccinia virus genome were expressed and tested using responder cells from 20 blood samples from 11 vaccinees. Validation assays established the sensitivity and specificity of the system. Overall, CD4 responses were detected for 122 ORFs (68%). A mean of 39 ORFs were recognized per person (range, 13 to 63). The most frequently recognized ORFS were present in virions, including A3L and A10L (core proteins), WR148 (a fragmented homolog of an orthopoxvirus protein that forms inclusions in cells), H3L (a membrane protein), D13L (a membrane scaffold protein), and L4R (a nucleic acid binding protein). Serum immunoglobulin G profiling by proteome microarray detected responses to 45 (25%) of the ORFs and confirmed recent studies showing a diverse response directed to membrane and nonmembrane antigens. Our results provide the first empirical whole-proteome data set regarding the global CD4 response to full-length proteins in a complex virus and are consistent with the theory that abundant structural proteins are immunodominant.

Antigen-specific therapy of rheumatoid arthritis

BACKGROUND

Immunotherapy offers the promise of antigen-specific suppression of pathological immune responses in conditions such as autoimmunity and organ transplantation. Substantial advances have been made in recent years in terms of understanding basic immunological mechanisms of autoreactivity, as well as clinically implementing immune-based therapies that are antigen nonspecific.

OBJECTIVE

To provide an integrated overview of the current state of the art in terms of antigen-specific tolerance induction, as well as to predict future directions for the field.

METHODS

Examples of successes and failures of antigen-specific immunotherapy were sought. Particular attention was paid to the well-established collagen II-induced model of arthritis.

RESULTS/CONCLUSIONS

Previous failures of antigen-specific immunotherapy were associated with lack of identification of clinically relevant antigens, as well as inappropriate tolerogenic methodologies. The advances in proteomics combined with novel gene-specific immune modulatory techniques place today's translational researchers in a unique position to tackle the problem of antigen-specific immunotherapeutic protocols.

Inhibition of macropinocytosis blocks antigen presentation of type II collagen in vitro and in vivo in HLA-DR1 transgenic mice

Professional antigen-presenting cells, such as dendritic cells, macrophages and B cells have been implicated in the pathogenesis of rheumatoid arthritis, constituting a possible target for antigen-specific immunotherapy. We addressed the possibility of blocking antigen presentation of the type II collagen (CII)-derived immunodominant arthritogenic epitope CII_259–273 to specific CD4 T cells by inhibition of antigen uptake in HLA-DR1-transgenic mice in vitro and in vivo. Electron microscopy, confocal microscopy, subcellular fractionation and antigen presentation assays were used to establish the mechanisms of uptake, intracellular localization and antigen presentation of CII by dendritic cells and macrophages. We show that CII accumulated in membrane fractions of intermediate density corresponding to late endosomes. Treatment of dendritic cells and macrophages with cytochalasin D or amiloride prevented the intracellular appearance of CII and blocked antigen presentation of CII_259–273 to HLA-DR1-restricted T cell hybridomas. The data suggest that CII was taken up by dendritic cells and macrophages predominantly via macropinocytosis. Administration of amiloride in vivo prevented activation of CII-specific polyclonal T cells in the draining popliteal lymph nodes. This study suggests that selective targeting of CII internalization in professional antigen-presenting cells prevents activation of autoimmune T cells, constituting a novel therapeutic strategy for the immunotherapy of rheumatoid arthritis.

T cell responses to a non-glycosylated epitope predominate in type II collagen-immunised HLA-DRB1*0101 transgenic mice

AIM

To study collagen-induced arthritis in human leucocyte antigen (HLA)-DR1 transgenic mice lacking endogenous major histocompatibility complex class II molecules (MHC-II) and to determine T cell specificity against the arthritogenic CII(259-273) epitope of type II collagen either unmodified or post-translationally glycosylated at Lys(264).

METHODS

Arthritis was induced by immunisation with human type II collagen in complete Freund's adjuvant and measured by footpad swelling, clinical score and histology. T cell responses were assessed by proliferation of spleen and lymph node cells and in antigen presentation assays, using T cell hybridomas specific for the glycosylated and non-glycosylated CII(259-273) epitope.

RESULTS

The incidence of arthritis was 50% in DR1-transgenic mice lacking endogenous MHC-II molecules. Recall T cell responses in draining lymph nodes and spleen were consistently greater against the non-glycosylated epitope than to the glycosylated CII(259-273). Most of the T cell hybridomas generated from CII-immunised mice recognised the non-glycosylated CII epitope and this form of the epitope was also presented with 100-fold higher efficiency and 1 h faster kinetics by both macrophages and dendritic cells.

CONCLUSION

This study shows that T cell responses to the non-glycosylated epitope of heterologous (human) CII are dominant in HLA-DR1 transgenic mice lacking MHC-II, which could contribute to the pathogenicity of autoimmune arthritis.

Humanized mouse models for organ-specific autoimmune diseases

Murine models for human autoimmune diseases are an essential tool for studying pathogenesis and for identifying new therapeutic targets. Mice are not the natural disease host, and conventional models have proved to be poor predictors of efficacy and safety in recent trials aiming to translate drug and biologic treatments to humans. Evidently, further steps towards recapitulating human diseases are urgently needed, for example using transgenic predisposing human HLA allele(s) plus T-cell receptor(s) implicated in a representative patient's autoimmune disease. The latest development - humanizing most of the immune system by transplanting human hematopoietic stem cells into severely immunodeficient mice - should lead to even better modeling.

Mechanisms of major histocompatibility complex class II-restricted processing and presentation of the V antigen of Yersinia pestis

We mapped mouse CD4 T-cell epitopes located in three structurally distinct regions of the V antigen of Yersinia pestis. T-cell hybridomas specific for epitopes from each region were generated to study the mechanisms of processing and presentation of V antigen by bone-marrow-derived macrophages. All three epitopes required uptake and/or processing from V antigen as well as presentation to T cells by newly synthesized major histocompatibility complex (MHC) class II molecules over a time period of 3-4 hr. Sensitivity to inhibitors showed a dependence on low pH and cysteine, serine and metalloproteinase, but not aspartic proteinase, activity. The data indicate that immunodominant epitopes from all three structural regions of V antigen were presented preferentially by the classical MHC class II-restricted presentation pathway. The requirement for processing by the co-ordinated activity of several enzyme families is consistent with the buried location of the epitopes in each region of V antigen. Understanding the structure-function relationship of multiple immunodominant epitopes of candidate subunit vaccines is necessary to inform choice of adjuvants for vaccine delivery. In the case of V antigen, adjuvants designed to target it to lysosomes are likely to induce optimal responses to multiple protective T-cell epitopes.

Therapeutic vaccination of active arthritis with a glycosylated collagen type II peptide in complex with MHC class II molecules

In both collagen-induced arthritis (CIA) and rheumatoid arthritis, T cells recognize a galactosylated peptide from type II collagen (CII). In this study, we demonstrate that the CII259-273 peptide, galactosylated at lysine 264, in complex with Aq molecules prevented development of CIA in mice and ameliorated chronic relapsing disease. In contrast, nonglycosylated CII259-273/Aq complexes had no such effect. CIA dependent on other MHC class II molecules (Ar/Er) was also down-regulated, indicating a bystander vaccination effect. T cells could transfer the amelioration of CIA, showing that the protection is an active process. Thus, a complex between MHC class II molecules and a posttranslationally modified peptide offers a new possibility for treatment of chronically active autoimmune inflammation such as rheumatoid arthritis.